Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Sinemurian (Early Jurassic) stratigraphy at Last Creek, British Columbia and Five Card Draw, Nevada :… Hou, Pengfei 2014

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
24-ubc_2014_september_hou_pengfei.pdf [ 13.04MB ]
Metadata
JSON: 24-1.0165994.json
JSON-LD: 24-1.0165994-ld.json
RDF/XML (Pretty): 24-1.0165994-rdf.xml
RDF/JSON: 24-1.0165994-rdf.json
Turtle: 24-1.0165994-turtle.txt
N-Triples: 24-1.0165994-rdf-ntriples.txt
Original Record: 24-1.0165994-source.json
Full Text
24-1.0165994-fulltext.txt
Citation
24-1.0165994.ris

Full Text

  SINEMURIAN (EARLY JURASSIC) STRATIGRAPHY AT LAST CREEK, BRITISH COLUMBIA AND FIVE CARD DRAW, NEVADA: PALEONTOLOGY AND ENVIRONMENTAL IMPLICATIONS by  PENGFEI HOU M.Sc., China University of Petroleum (Beijing), 2012 B.Sc., China University of Geosciences (Beijing), 2009  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Geological Sciences)  THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver)   August 2014  © Pengfei Hou, 2014ii  ABSTRACT  Over 400 ammonite specimens were collected from the Last Creek Formation in Last Creek, British Columbia and the Sunrise Formation in Five Card Draw, Nevada. A detailed taxonomic study from the Involutum Zone to the lower part of the Harbledownense Zone of the Sinemurian is presented. At least 38 species are identified and described, distributed amongst 15 genera and 5 families. Three species are introduced as new: Tipperoceras n. sp. A, Tmaegoceras obesus n. sp., Arnioceras n. sp. A. Also, Echioceratidae gen. et sp. indet. is tentatively introduced as a new species and genus. The following zones of the current Sinemurian zonation for western North America (Taylor et al., 2001) can be recognized, based on the stratigraphical distribution of the taxa identified, namely the Involutum, Leslei, Carinatum and Harbledownense zones in ascending order. The Jamesi Zone placed between the last two by Taylor et al. (2001) cannot be recognized in the study areas in either Canada or the United States and therefore it is removed from the current zonation scheme. A revised zonation and definition of the zones, with precise correlation to the primary standard northwest European zonation, are provided. The transgressive and regressive events in both Last Creek and Five Card Draw are calibrated with the revised Sinemurian zonation. Their relationships with eustatic changes as well as ammonite biodiversity and faunal turnover are also investigated.  The Early Sinemurian transgression proposed by Hallam (1981, 1988) is well represented in both the Last Creek and Five Card Draw sections, and co-occurs with ammonite diversity maxima and a possible global positive CIE (carbon isotope excursion). The mid-Late Sinemurian regression and Late Sinemurian transgression are represented by facies and palebathymetric changes in Five Card Draw. The contrast in paleobiodiversity and faunal turnover as well as in carbon and osmium isotope profiles of the two study areas suggest significant differences in depositional environment, relative connection to the open ocean, and differences in terrestrial sediment input.  iii  PREFACE  This thesis is a combination of both unpublished and published materials. I was responsible for all related field and lab work for Chapters 1, 2, 3, 4, 6 and 7 with the supervision of Dr. Paul L. Smith. These chapters will be modified and submitted for publication. Dr. Paul L. Smith will provide guidance with the structure of the article and the writing process. My field work in 2012 and 2013 was assisted by Paul. L. Smith, Andrew Caruthers, Sara Porter and Kate Gordanier-Smith. Chapter 5 Geochemistry is modified from the following journal article listed in Appendix C.   Porter, S. J., Smith, P. L., Caruthers, A. H., Hou, P., Gröcke, D. R., Selby, D., 2014. New high resolution geochemistry of Lower Jurassic marine sections in western North America: a global positive carbon isotope excursion in the Sinemurian? Earth and Planetary Science Letters, v. 397, p. 19-31.   This article is the result of the collaboration between the Paleontology Laboratory in UBC led and funded by Paul L. Smith and Durham Geochemistry Center at University of Durham (UK) partially funded by Darren R. Gröcke. I wrote the ‘Biochronology’ section in this article and drew Figs. 3 & 4, and partially Figs. 5, 6 & 8.iv  TABLE OF CONTENTS  ABSTRACT ....................................................................................................................ii PREFACE ..................................................................................................................... iii TABLE OF CONTENTS ............................................................................................... iv LIST OF FIGURES ......................................................................................................... x LIST OF TABLES ....................................................................................................... xiv LIST OF PLATES ......................................................................................................... xv ACKNOWLEDGEMENTS .......................................................................................... xvi DEDICATION ........................................................................................................... xviii CHAPTER 1       INTRODUCTION ............................................................................... 1 1.1  Purpose of Study ............................................................................................... 1 1.2  Introduction to study areas ................................................................................ 3 1.3  Previous work ................................................................................................... 4 1.4  Methods ............................................................................................................ 5 CHAPTER 2       GENERAL GEOLOGY ....................................................................... 7 2.1  General Geology of Last Creek, British Columbia ............................................. 7 2.1.1  Tectonics .................................................................................................... 7 2.1.2  Stratigraphy................................................................................................ 9 2.2  General Geology of Five Card Draw, Nevada .................................................. 11 2.2.1  Tectonics .................................................................................................. 11 2.2.2  Stratigraphy.............................................................................................. 11 CHAPTER 3       BIOSTRATIGRAPHY AND BIOCHRONOLOGY ........................... 18 v  3.1  Introduction ..................................................................................................... 18 3.2  Sinemurian Zonation of Western North America ............................................. 19 3.2.1  Abandonment of the Jamesi Zone ............................................................. 22 3.2.2  Revised definitions of the zones ............................................................... 23 3.3  Biostratigraphy of Measured Sections ............................................................. 25 3.3.1  Last Creek, British Columbia ................................................................... 25 3.3.2  Five Card Draw, Nevada .......................................................................... 29 3.4  Correlation and Biochronology ....................................................................... 33 3.4.1  Correlation between Last Creek and Five Card Draw ............................... 33 3.4.2  Correlation with Northwest Europe .......................................................... 34 CHAPTER 4       SEA LEVEL CHANGE AND AMMONITES .................................... 37 4.1  Introduction ..................................................................................................... 37 4.2  Sea level change in study areas ........................................................................ 39 4.2.1  Last Creek, British Columbia ................................................................... 39 4.2.2.  Five Card Draw, Nevada .......................................................................... 46 4.3  Sea level change and ammonoid diversity ....................................................... 51 CHAPTER 5       GEOCHEMISTRY ............................................................................ 56 5.1  Introduction ..................................................................................................... 56 5.2  Analytical results............................................................................................. 58 5.2.1  Total Organic Carbon (TOC) and δ13Corg .................................................. 58 5.2.2  Rhenium and osmium abundance and isotope data ................................... 60 5.3  Discussion ....................................................................................................... 62 5.3.1  Comparing carbon isotope profiles from Five Card Draw and Last Creek . 62 vi  5.3.2  Comparing Five Card Draw to Last Creek: restricted vs. open-ocean? ...... 63 5.3.3  A global carbon isotope excursion at Last Creek? ..................................... 67 5.4  Conclusion ...................................................................................................... 70 CHAPTER 6       SYSTEMATIC PALEONTOLOGY .................................................. 72 6.1  Introduction ..................................................................................................... 72 6.2  Measurements and Abbreviations .................................................................... 73 6.3  Systematic descriptions ................................................................................... 74 Family PLEUROACANTHITIDAE Hyatt, 1900 ....................................................... 74 Subfamily FUCINITINAE Venturi & Ferri, 2001 ...................................................... 74 Genus FUCINITES Gugenberger, 1936. .................................................................... 74 Fucinites sicilianus GUGENBERGER, 1936 ......................................................... 75 Family ECTOCENTRITIDAE Spath, 1926 ............................................................... 78 Genus ECTOCENTRITES Canavari, 1888 ................................................................ 78 Ectocentrites leslei (TAYLOR, GUEX & RAKÚS 2001) ....................................... 78 Family LYTOCERATIDAE Neumayr, 1875 ............................................................. 82 Subfamily LYTOCERATINAE Neumayr, 1875 ........................................................ 82 Genus LYTOCERAS Suess, 1865 ............................................................................. 82 Lytoceras sp. .......................................................................................................... 83 Family ARIETITIDAE Hyatt, 1875 ........................................................................... 85 Subfamily ALSATITINAE Spath, 1924 ..................................................................... 85 Genus TIPPEROCERAS Taylor, 1998 ...................................................................... 85 Tipperoceras mullerense TAYLOR, 1998 .............................................................. 85 Tipperoceras n. sp. A ............................................................................................. 87 vii  Subfamily ARIETITINAE Hyatt, 1875 ...................................................................... 89 Genus TMAEGOCERAS Hyatt, 1889 ....................................................................... 89 Tmaegoceras nudaries TAYLOR, 1998 ................................................................. 90 Tmaegoceras crassiceps POMPECKJ, 1901 ........................................................... 91 Tmaegoceras cf. latesulcatum (HAUER, 1856) ...................................................... 93 Tmaegoceras obesus n. sp. ..................................................................................... 95 Genus CORONICERAS Hyatt, 1867 ......................................................................... 97 Coroniceras multicostatum (SOWERBY, 1824) ..................................................... 98 Coroniceras cf. lyra HYATT, 1867 ...................................................................... 100 Coroniceras cf. mutabile MACCHIONI, SMITH & TIPPER, 2005 ...................... 104 Coroniceras charlesi DONOVAN, 1955 .............................................................. 106 Coroniceras cf. involutum TAYLOR 1998 ........................................................... 107 Genus ARNIOCERAS Hyatt, 1867 .......................................................................... 109 Arnioceras ceratitoides (QUENSTEDT, 1848) ..................................................... 110 Arnioceras arnouldi (DUMORTIER, 1867) ......................................................... 115 Arnioceras cf. arnouldi (DUMORTIER, 1867) .................................................... 119 Arnioceras semicostatum (YOUNG & BIRD, 1828)............................................. 120 Arnioceras cf. oppeli GUÉRIN-FRANIATTE, 1966 ............................................ 122 Arnioceras densicosta (QUENSTEDT, 1884) ....................................................... 124 Arnioceras miserabile (QUENSTEDT, 1858) ....................................................... 126 Arnioceras n. sp. A ............................................................................................... 130 Family ARIETITIDAE Hyatt, 1875 ......................................................................... 133 Subfamily ASTEROCERATINAE Spath, 1946 ....................................................... 133 viii  Genus CAENISITES Buckman, 1925 ...................................................................... 133 Caenisities brooki (SOWERBY, 1818) ................................................................. 134 Caenisities turneri (SOWERBY, 1824) ................................................................ 136 Caenisites sp. ....................................................................................................... 138 Genus ASTEROCERAS HYATT, 1867 .................................................................. 140 Asteroceras cf. varians FUCINI, 1903 ................................................................. 141 Asteroceras cf. margarita (PARONA, 1896) ........................................................ 143 Asteroceras sp. ..................................................................................................... 145 Genus EPARIETITES Spath, 1924 .......................................................................... 147 Eparietites ex gr. impedens (YOUNG & BIRD, 1928) ......................................... 147 Genus EPOPHIOCERAS Spath, 1924 ..................................................................... 150 Epophioceras carinatum SPATH, 1924 ................................................................ 151 Epophioceras cf. carinatum SPATH, 1924 ........................................................... 153 Epophioceras cf. wendelli TAYLOR, GUEX & RAKÚS, 2001 ............................ 154 Epophioceras sp. .................................................................................................. 156 Family ECHIOCERATIDAE Buckman, 1913 ......................................................... 158 Genus PALTECHIOCERAS Buckman, 1924 .......................................................... 158 Paltechioceras cf. harbledownense (CRICKMAY, 1928) ..................................... 160 Paltechioceras boehmi (HUG, 1899) .................................................................... 161 Genus PALAEOECHIOCERAS Spath, 1929 ........................................................... 164 Palaeoechioceras cf. spirale (TRUEMAN & WILLIAMS, 1927) ........................ 165 Echioceratidae gen. et sp. indet. ............................................................................... 168 CHAPTER 7       CONCLUSIONS .............................................................................. 170 ix  PLATES ...................................................................................................................... 172 REFERENCES............................................................................................................ 204 APPENDICES ............................................................................................................ 231 Appendix A  FOSSIL LOCALITIES ....................................................................... 231 Appendix B  AMMONITE BIODIVERSITY .......................................................... 236 Appendix C  PUBLICATION ................................................................................. 241  x  LIST OF FIGURES  Fig. 1-1 Location maps of study areas ............................................................................. 2  Fig. 2-1 Tectonic setting of Last Creek and locations of measured sections ...................... 8  Fig. 2-2 Lithologic units of the Last Creek Formation...................................................... 9  Fig. 2-3 Lithostratigraphic units of Sunrise Formation and their ages at the Gabbs Valley Range. ............................................................................................................... 12  Fig. 2-4 Tectonic setting of Five Card Draw, and location of studied sections ................ 13  Fig. 2-5 Photographs of Five Card Draw and New York Canyon, Nevada. ..................... 14  Fig. 2-6 Photographs of polished tuff samples collected from section FCD1, Five Card Draw Member. ................................................................................................... 15  Fig. 3-1 Composite species range chart of Sinemurian of Last Creek, BC and Five Card Draw, Nevada .................................................................................................... 20  Fig. 3-2 The original composite range chart for the Sinemurian of western North America (Fig. 7 of Taylor et al., 2001). ............................................................................. 21  Fig. 3-3 A revised Sinemurian zonation for western North America and updated correlation with northwest Europe ....................................................................................... 23  Fig. 3-4 Biostratigraphy of section LC1 at Last Creek, British Columbia. ...................... 27  Fig. 3-5 Biostratigraphy of section LC2 at Last Creek, British Columbia ....................... 28 xi  Fig. 3-6 Biostratigraphy of Section FCD1 at Five Card Draw, Nevada ........................... 30  Fig. 3-7 Biostratigraphy of Section FCD2 at Five Card Draw, Nevada ........................... 32  Fig. 3-8 Biostratigraphic correlation between measured sections in Last Creek, British Columbia and Five Card Draw, Nevada ............................................................. 34  Fig. 4-1 Eustatic curves for the Early Jurassic plotted against periods of black shale deposition .......................................................................................................... 38  Fig. 4-2 Early Sinemurian transgression recorded in Last Creek, British Columbia (section LC1) .................................................................................................................. 42  Fig. 4-3 Early Sinemurian transgression recorded in Five Card Draw, Nevada (section FCD1) ............................................................................................................... 48  Fig. 4-4 Mid-Late Sinemurian transgression recorded in Five Card Draw, Nevada (section FCD2). .............................................................................................................. 50  Fig. 4-5 Eustatic fluctuations and ammonite diversity in the study areas. ....................... 52  Fig. 5-1 TOC, δ13Corg, and Re-Os isotope profiles for FCD1 and FCD2 ......................... 59  Fig. 5-2 TOC, δ13Corg,and Re-Os isotope profiles for LC1 and LC2. .............................. 61  Fig. 5-3  Plot comparing the initial 187Os/188Os values for FCD1 (blue squares), LC1 (solid red squares) and LC2 (hollow red squares). ........................................................ 64  Fig. 5-4  Figure comparing δ13Corg data from western North America (Five Card Draw and Last Creek; this study) with a coeval δ13Corg dataset from Europe (Dorset, UK; xii  Jenkyns and Weedon, 2013). .............................................................................. 68  Fig. 6-1 Shell size (D), whorl height (WH), and rib frequency (PRHW) plots of Ectocentrites leslei, compared with that of Meister et al. (2002), Taylor et al. (2001) and Pálfy (1991). ............................................................................................... 81  Fig. 6-2 Septal suture of Lytoceras sp. . ......................................................................... 84  Fig. 6-3 Tipperoceras mullerense, whorl sections with growth. ...................................... 87  Fig. 6-4 Whorl section of Tmaegoceras nudaries. .......................................................... 91  Fig. 6-5 Whorl section of Tmaegoceras obesus n. sp.. ................................................... 96  Fig. 6-6 Septal suture of Coroniceras cf. lyra .............................................................. 103  Fig. 6-7 Septal sutures of Arnioceras ceratitoides ........................................................ 113  Fig. 6-8 Shell size (D), whorl height (WH) and rib frequency (PHRW) plots against umbilical diameter (UD) of Arnioceras ceratitoides, compared with that of Schlegelmilch (1976), Géczy & Meister (2007), Smith (1981), Braga et al. (1984), Wang & Smith (1986). ..................................................................................... 115  Fig. 6-9 Shell size (D), whorl height (WH) and rib frequency (PRHW) plots of Arnioceras arnouldi, compared with Guérin-Franiatte (1966, refigured holotype and lectotype figured therein). ............................................................................................... 119  Fig. 6-10 Shell size (D), whorl height (WH), whorl expansion rate (EXP) plotted against umbilical diameter (UD) of Arnioceras miserabile, compared with that of (Guérin-Franiatte, 1966, neotype refigured therein). ...................................................... 130  xiii  Fig. 6-11 Whorl section of Arnioceras n. sp. A. ........................................................... 132  Fig. 6-12 Whorl section of Caenisites sp...................................................................... 138  Fig. 6-13 Septal suture of Epophioceras cf. wendelli ................................................... 155  Fig. 6-14 Whorl section of Echioceratidae gen. et sp. indet. ......................................... 168  Fig. 6-15 Septal sutures of Echioceratidae gen. et sp. indet. ......................................... 169    xiv  LIST OF TABLES  Table 4-1 Estimation of the controlling factors of local sea level change and their contributions to Early Sinemurian transgression in Last Creek. .......................... 43  Table 4-2 Composite faunal assemblages of marine invertebrates and depositional environment. ...................................................................................................... 46 xv  LIST OF PLATES  Plate 1  Fucinites sicilianus …………………………………………………………………………173  Plate 2  Ectocentrites leslei, Lytoceras sp., Tipperoceras mullerense, Tipperoceras n. sp. A, Tmaegoceras nudaries ……………………………………………………………..…..175  Plate 3  Tipperoceras mullerense …………………………………………………………...……..177  Plate 4  Tmaegoceras crassiceps, Tmaegoceras cf. latesulcatum, Tmaegoceras obesus n. sp.  ……………………………………………………………………………………..……….179  Plate 5  Coroniceras sp., Coroniceras cf. lyra, Coroniceras multicostatum …………..…181  Plate 6  Coroniceras cf. mutabile, Coroniceras charlesi, Arnioceras ceratitoides ……..183  Plate 7  Coroniceras cf. involutum …………………………………………………………….….185  Plate 8  Arnioceras ceratitoides, Arnioceras arnouldi ………………………………………..187  Plate 9  Arnioceras semicostatum, Arnioceras cf. arnouldi, Arnioceras arnouldi …...…189  Plate 10  Arnioceras cf. oppeli, Arnioceras densicosta, Arnioceras miserabile ………...191  Plate 11  Arnioceras miserabile, Arnioceras n. sp. A, Caenisites turneri, Caenisites sp.  ……………………………………………………………………….……………………..193   Plate 12  Caenisites brooki …………………………………………………………………………195  Plate 13  Asteroceras cf. varians, Asteroceras sp., Asteroceras cf. margarita …………..197  Plate 14  Eparietites ex gr. impedens, Epophioceras cf. wendelli, Epophioceras carinatum, Epophioceras cf. carinatum ……………………………………………..…199  Plate 15  Epophioceras sp., Paltechioceras cf. harbledownense, Paltechioceras boehmi, Palaeoechioceras cf. spirale, Echioceratidae gen. et sp. indet. ………………...…201  xvi  ACKNOWLEDGEMENTS  Words cannot describe my gratefulness to my supervisor Dr. Paul L. Smith for his tireless guidance, financial support, assistance and advice in the past three years, as well as the opportunity for me to walk into this world famous institute and begin a new odyssey in my life which can never be overrated. I also appreciate his broad vision and wisdom as a scientist, great sense of humor and easy-going personality. I feel indebted to him and his wife Kate Gordanier-Smith for their hospitality and endless support.  Much gratitude also goes to my supervisory committee. Dr. Stuart J. E. Sutherland (UBC) greatly enhanced my knowledge in his course Advance Paleontology and gave me many helpful suggestions on paleontology and sedimentology in my research. His great sense of humor and optimistic personality have been an important source of encouragement. Dr. James K. Mortensen (UBC) helped me identify tuff samples and taught me some principles of geochronology and zircon mineralogy. His research enthusiasm has always been energizing. Dr. James W. Haggart (GSC) helped me get access to the Sinemurian ammonite collections and files in the Geological Survey of Canada and arrange fossil repository. He also provided some useful advice on biostratigraphy.   Many thanks to my colleagues in the paleontology lab and the EOAS department in UBC. Dr. Andrew H. Caruthers gave me extensive help and assistance in almost every aspect of my research during our years of overlap in the lab. His help and experience, particularly with major technical problems, saved me months if not years of time. His companionship allowed me to feel like I had a big brother in Canada! Dr. Louise M. Longridge provided many insightful suggestions on ammonite taxonomy and biostratigraphy. She also kindly lent me many references from her own library. Dr. Sarah J. Porter was in charge of the isotope geochemistry work and provided field assistance during the summer of 2012. Discussions with Dr. Martyn L. Golding and Dr. Randal A. Mindell have been informative and encouraging. They always helped!  xvii  I also need to thank many other individuals. Special thanks to Mr. W. Cory Brimblecombe and Mr. Rod M. Bartlett of the Vancouver Paleontology Society who taught me how to make fossil casts. Their advice and experience saved me months of work as I prepared my specimens. Cory also kindly gave me a cast specimen of a perfectly-preserved Caenisites from Last Creek to supplement my collection. Mr. Peter Krauss and Ms. Hillary Taylor of the GSC provided useful information about the warehouse and about Dr. H. W. Tipper’s collections and documents. Sedimentological discussion with my friend Mr. Yuefeng Shen of Laval University, particularly in carbonate platform settings, is very informative. He also helped me gain access to various journal articles. Finally, my collaborators who helped with the isotope geochemistry work in both UBC and the University of Durham cannot be neglected. A separate acknowledgement is given to them in the article in Appendix C.   xviii  DEDICATION  To my Dad, Xiangyu Hou, who planted the seed of hope in my name “Peng Fei”, which means: fly, my bird!  1  CHAPTER 1       INTRODUCTION  1.1  Purpose of Study  The Early Jurassic was a time of significant changes in the Earth system and included the continuing fragmentation of Pangaea and marine transgressions It also saw widespread black shale deposition and anoxic events, the understanding of which requires precise biochronologic calibration and correlation. The importance of a regional ammonoid zonation scheme for the Jurassic has been long recognized and discussed, and a North American zonation for the Lower Jurassic was established for the Pliensbachian by Smith et al. (1988), the Toarcian by Jakobs et al. (1994) and finally the Hettangian and Sinemurian by Taylor et al. (2001). The discovery of carbon isotope excursions in the Sinemurian in Europe (e.g., Jenkyns and Weedon, 2013; Riding et al., 2013) suggested significant changes in the marine environment and highlighted to the importance of improving our understanding of coeval sequences in North America and elsewhere if we are to detect global events. The current Sinemurian zonation of western North America is based on successions in the western US and Mexico but also incorporates the work of Pálfy et al. (1994) in Haida Gwaii (formerly Queen Charlotte Islands) in British Columbia. However, this zonation did not include systematic descriptions except for new taxa. Also, it has not been tested elsewhere in North America and a large dataset in Canada is still not yet incorporated (Fig. 1-1 A). In summary, the goals of this study are:    To provide a biochronological framework for a related study of isotope geochemistry of the Sinemurian in western North America.   To provide a complete taxonomic treatment of the Sinemurian ammonite fauna from the Involutum Zone to the lower part of the Harbledownense Zone collected 2  from Last Creek, British Columbia and Five Card Draw, Nevada.   To test the current Sinemurian zonation scheme for western North America, and make revisions if necessary.   To recognize potential eustatic changes in the study areas and examine the relationships with ammonite diversity and faunal turnovers.     Fig. 1-1 Location maps of study areas. A. Most important Sinemurian ammonoid localities in western North America (after Taylor et al., 2001); B. Location map of Last Creek in Taseko Lakes area, southwestern British Columbia; C. Location map of Five Card Draw and New York Canyon in Gabbs Valley Range, west central Nevada.   3  1.2  Introduction to study areas  Last Creek is a northern tributary of Tyaughton Creek in the Taseko Lakes map area (NTS 92-O) in southwestern British Columbia, Canada. It is located approximately 160 km north of Whistler (Fig. 1-1), in the southeastern part of the Chilcotin Ranges of the Coast Mountains and east of the Taseko Lakes. The field area is in the headwaters of Last Creek, at an elevation over 2200 m. Conditions can be very variable with temperatures fluctuating around 0°C sometimes even in the summer. Access to the sections was gained by off-road vehicles via the logging road network near the Spruce Lake Protected area, and then by helicopter.  Five Card Draw and the southerly neighboring New York Canyon are two valleys of the Gabbs Valley Range in the Mineral County in west-central Nevada, USA. The field area is east of Walker Lake, approximately 50 km east of Hawthorne (Fig. 1-1), at an elevation over 1600 m. The sections are accessible by off-road vehicles via US highway 95 and a network of unpaved roads. Although most of the work was done in Five Card Draw, a minor collection was made along the unmeasured section and from several localities near the entrance of New York Canyon to supplement the Five Card Draw collection.  The measured sections are coded with the acronyms of the study areas (LC1, LC2, FCD1 and FCD2 respectively), and collections are coded with the first letter of the study areas plus the locality numbers (e.g., L1-01 for fossil locality 01 in section LC1). Some of the collections from the Geological Survey of Canada (Vancouver) and Dr. Paul Smith’s PhD study (Smith, 1981) are also incorporated into this work. The localities from measured and unmeasured sections and details of coding are listed in the Appendix A.    4  1.3  Previous work  Last Creek, British Columbia Early reconnaissance and mapping of the southeastern Chilcotin Ranges in the Taseko Lakes map area began in the early 1920s. Late Triassic to Jurassic fossil localities were recorded along the Tyaughton Creek and systematic investigation of the Early Jurassic fauna in started from the 1940s (Cairnes, 1943). Beginning in the 1960s, more collections were made during mapping of the Taseko Lakes area (92-O) by the Geological Survey of Canada and the British Columbia Geological Survey; work by universities and amateur societies also enhanced our understanding of this area (Tipper, 1963, 1978; Frebold and Tipper, 1970; Umhoefer et al., 1988; Umhoefer, 1990; Schiarizza et al., 1997; Smith et al., 1998). A comprehensive summary of the stratigraphy, sedimentology and tectonics of the Chilcotin Ranges was given by Umhoefer (1990) and Umhoefer and Tipper (1998). The most recent geologic map of the Taseko Lakes map area (92-O) was published by the Geological Survey of Canada in 2013 by Mahoney et al.  The ammonoid fauna from the headwaters of Last Creek was originally interpreted as Hettangian by Frebold (1967) but was reexamined by O’Brien (1985), who suggested an Early Sinemurian age. The latest Early Sinemurian ammonoid fauna from Last Creek and the neighboring areas (Castle Pass, Little Paradise Creek and Reid Creek) have been described by Macchioni et al. (2005, 2006). The Hettangian-Sinemurian boundary has been investigated by Smith and Tipper (2000), and later by Longridge et al. (2006) who revised the North American Zonation across the Hettangian-Sinemurian boundary primarily based on their work with the Badouxia fauna from the Last Creek and the neighboring areas. Currently, no other biostratigraphic work has been published for the remainder of the Sinemurian in Taseko Lakes map area.                                                                                                                                                                                                         5  Five Card Draw, Nevada Nevada has the best exposed sections of marine Lower Jurassic in the United States (Imlay, 1971). The geologic mapping by Muller and Ferguson (1939), and the report on the structural geology of the Hawthorne and Tonopah quadrangles (Ferguson and Muller, 1949), established the framework for all subsequent studies in this area (Fig. 1-1).  In the 1950s and 1960s, some studies of the Lower Jurassic successions were made in Nevada (Silberling, 1959; Corvalan, 1962). Hallam (1965) briefly summarized the previous work and made a provisional biostratigraphic correlation among the Lower Jurassic successions in the United States. More progress was made on the paleontology and biostratigraphy of this sequence during the 1970s and 1980s (e.g., Guex and Taylor, 1976; Guex, 1980). Smith (1981) made a comprehensive study of the biostratigraphy of the Lower Jurassic, including the first systematic treatment of the Sinemurian ammonite fauna in Nevada. Later, the lithostratigraphic units of west-central Nevada were formally reinterpreted and named by Taylor et al. (1983). The Late Hettangian-Early Sinemurian ammonite successions in Nevada and Oregon were dealt with by Taylor (1998) who used New York Canyon as one of the reference sections. The Sinemurian ammonoid zonation scheme for the western Cordillera in North America was published by Taylor et al. (2001), although much of the Canadian data were not included. Five Card Draw was selected as the type section. There have been many publications dealing with the base of Jurassic System in New York Canyon and its potential as a type section for the Triassic-Jurassic boundary (e.g., Guex et al., 2004), but little attention has been paid to the Sinemurian of the Gabbs Valley Range.   1.4  Methods  One week of extensive collecting was spent in Last Creek during the summer of 2012 and two weeks in Five Card Draw in 2012 and 2013 combined. Two sections were 6  measured from each of the study areas and bed-by-bed collections were made wherever ammonoid specimens were available. The Brunton compass and tape technique was used in Last Creek and measurements were converted to true thickness, while the Jacob’s staff method was used in Five Card Draw. There are 26 ammonoid localities recorded from the measured sections in Last Creek, with an average sampling interval of 2.1 m, and 64 ammonoid localities recorded in Five Card Draw, with an average sampling interval of 2.5 m. Localities (both in situ and ex situ) that are not from the measured sections are also recorded to support the collection from measured sections. Some of the unpublished work and preexisting Sinemurian collections from Last Creek which accumulated in the past few decades under the leadership of Dr. H. W. Tipper and housed in the Geological Survey of Canada (Vancouver), have been incorporated into this work. Similarly, some of the Sinemurian specimens from Five Card Draw from Dr. P. L. Smith’s doctoral study at McMaster University (now housed at UBC) are also reexamined and incorporated. The specimens figured herein are stored at the National Invertebrate and Plant Type Fossil Collection at Natural Resources Canada, 601 Booth Street, Ottawa, Ontario.   The reprint collection of Jurassic literature and the AMMON database (Smith, 1986; Liang and Smith, 1997) are two major sources of information for the taxonomic study. The geochemistry study is related to this thesis work, the sampling and methodology of which are introduced in Appendix C.   7  CHAPTER 2       GENERAL GEOLOGY  2.1  General Geology of Last Creek, British Columbia  2.1.1  Tectonics     The Canadian Cordillera consists of the North American craton margin and numerous allochthonous terranes of various types, origins and ages. The Last Creek area lies within the Cadwallader terrane (Fig. 2-1 A) on the northeastern edge of the Coast Plutonic Complex, and west of the Yalakom Fault and the Fraser River Plateau (Umhoefer, 1990; Umhoefer and Tipper, 1998). The pre-Cretaceous lithologic components of the Cadwallader terrane can be generally divided into three units, in ascending stratigraphic order: Permian oceanic lithosphere, Triassic volcanic arc, and Upper Triassic to Middle Jurassic clastic sedimentary rocks  (Umhoefer, 1990; Monger and Nokleberg, 1996), which are unconformably overlain by the Middle Jurassic to Lower Cretaceous Relay Mountain Group, which also comprises clastic sedimentary rocks (Umhoefer and Tipper, 1998). The Cadwallader terrane is considered one of the ‘intermediate accreted terranes’ which are sandwiched by the older ‘inner accreted terranes’ and the younger ‘outer arc terranes’ (Monger and Nokleberg, 1996). It is thought that the Cadwallader terrane was an inactive, subsiding volcanic arc lying in the northeast Panthalassa Ocean during the Early and Middle Jurassic that was accreted to the craton during Middle to Late Jurassic (Umhoefer, 1990; Monger, 2011). This area was disrupted by mid-Cretaceous thrust faulting and Late Cretaceous to early Paleogene plutonic intrusion (Umhoefer and Schiarizza, 1993).    8    Fig. 2-1 Tectonic setting of Last Creek and locations of measured sections. A. Terrane map of southwestern British Columbia. CC: Cache Creek, QN: Quesnellia, ST: Stikinia, BR: Bridge River, CD: Cadwallader, CK: Chiliwack, HA: Harrison, MT: Methow, SH: Shuksan, WR: Wrangellia, PR: Pacific Rim, M: undivided metamorphic rock, after Wheeler and McFeely (1991) and Umhoefer and Tipper (1998); B. Topographic map. 9  showing the locations of measured sections (LC1 & LC2) in Last Creek; C. Geologic map of the headwaters of Last Creek (after Smith et al., 1998); D. Photograph of the headwaters of Last Creek.    2.1.2  Stratigraphy  In the Chilcotin Ranges of the Cadwallader Terrane, the Upper Triassic to Middle Jurassic rocks consist of three formations: the Triassic Tyaughton Formation, the Jurassic Last Creek Formation and the Jurassic Nemaia Formation, all of which are formally described and defined by Umhoefer and Tipper (1998). The interval studied in this work is part of the Last Creek Formation and is an Upper Hettangian to Lower Bajocian clastic sequence. It overlies the Tyaughton Formation by an erosional disconformity and is unconformably overlain by the Upper Jurassic to Cretaceous Relay Mountain Group.  Due to intensive faulting, there is no complete section representing the whole Formation but the good fossil record makes it possible to construct a composite section (Umhoefer and Tipper, 1998). The Sinemurian segments are best represented in Castle Pass, Last Creek, and southern Relay Creek, among which Last Creek is reported to have the most complete segments of Sinemurian (Umhoefer and Tipper, 1998).   Last Creek Formation Members Lithology Thickness Age Little Paradise Calcareous black shale, minor sandstone, rare conglomerate >300m  Mid-Early Sinemurian to Early Bajocian Castle Pass Volcanic-pebble conglomerate, brown medium to coarse grained sandstones, sandy siltstones, rare tuff bands ~150m Late Hettangian to Mid-Early Sinemurian    Fig. 2-2 Lithologic units of the Last Creek Formation (after Umhoefer and Tipper, 1998).  The Last Creek Formation is subdivided into the Castle Pass Member and the Little Paradise Member (Fig. 2-2). The Castle Pass Member (Upper Hettangian to mid-Lower 10  Sinemurian) is composed of interbedded volcanic-pebble conglomerate and brown to green sandstone, deposited in a near-shore to inner shelf environment. Well preserved ammonoids, gastropods and wood debris are common in this member (Frebold, 1967; O’Brien, 1985). The trace fossil Thalassinoides has been found from the base of the unit (Smith et al., 1998). The Little Paradise Member (mid-Lower Sinemurian to Lower Bajocian) is composed of brown to green calcareous siltstone, shale, black shale and minor sandstone, deposited in an outer shelf to slope environment. Calcareous concretions within the shale beds are common, and many of them yield well preserved ammonoids. Some highly fossiliferous beds (e.g., abundant bivalves, gastropods and ammonoids) can be potentially used as marker beds for local correlation. The formation is approximately 250 to 400 m thick and interpreted as a transgressive sequence (Umhoefer and Tipper, 1998; Macchioni et al., 2006). Based on the current work and the precise temporal control it provides, the most important transgressive surface is placed at the contact of the Castle Pass Member and the Little Paradise Member in this work, as discussed in more detail in Chapter 3 and 4.  There are two possible tuff beds recorded from Last Creek in this work within the shales of Little Paradise Member. The first one is immediately above the top of the section LC 1 and the second is at the base of section LC 2 (see Fig. 3-5 in Chapter 3 for detailed stratigraphic location). Both are generally light to dark gray in color with thin bright yellow bands about 5 mm thick, poorly weathered at the outcrop. The samples collected are all fragmented pieces no more than a few centimeters in size that did not yield any zircons. The presence of possible tuff beds within Last Creek Formation has been discussed in Umhoefer and Tipper (1998). Although no detailed stratigraphic locations of the tuff beds were recorded in their work, it is possible that our discoveries are correlative with some of theirs.     11  2.2  General Geology of Five Card Draw, Nevada   2.2.1  Tectonics  In west-central Nevada, Mesozoic sedimentary rocks were deposited in a back-arc basin, which consists of several terranes, and each terrane of several lithotectonic assemblages (Oldow, 1984; Taylor and Smith, 1992; Crafford, 2008). This basin is interpreted as a successor basin (Taylor and Smith, 1992; Aberhan, 1999) which formed upon either a Paleozoic continental margin basin (Burchfiel and Davis, 1972, 1975) or an allochthonous terrane accreted to the continent by mid-Triassic time (Speed, 1979). The Mesozoic sedimentary rocks cropping out in the Gabbs Valley Range are interpreted as part of the Pamlico-Luning lithotectonic assemblages (Fig. 2-4) of the Walker Lake terrane  which has a complex deformation history (Oldow, 1984; Silberling and Jones, 1984; Crafford, 2007). The Walker Lake terrane used to be included as part of the former Sonomia terrane  (Speed, 1979). This region was subjected to extensive thrust faulting during Middle / Late Jurassic and Early Cretaceous, resulting in a NW-SE contraction of the basin of up to several hundred kilometers (Oldow, 1984).    2.2.2  Stratigraphy   The Upper Triassic to Lower Jurassic rocks cropping out in the Gabbs Valley Range (No. 5 in Fig. 2-4 A) were first divided into four successive formations by Muller and Ferguson (1939) and Ferguson and Muller (1949), namely the Luning, Gabbs (Upper Triassic), Sunrise (Lower Jurassic) and Dunlap formations, in ascending order. The Gabbs and Sunrise formations, together forming the Volcano Peak Group, were formally described and redefined by Taylor et al. (1983) in an attempt to eliminate the confusion caused by multiple previous stratigraphic schemes (Fig. 2-3). All contacts of the units within the Volcano Peak Group are conformable.  The Sunrise Formation at the Gabbs Valley Range is a Hettangian to Pliensbachian 12  sequence composed of limestone and fine-grained clastic sediments deposited in a platform setting. It is subdivided into 5 members (Taylor et al., 1983), from the bottom to the top (Fig. 2-3): Ferguson Hill (Hettangian to basal Sinemurian); Five Card Draw and New York Canyon (Sinemurian); Joker Peak and Mina Peak (Pliensbachian). The total thickness is approximately 400 m. The Five Card Draw (Fig. 2-4; Fig. 2-5) which is also the type section for Five Card Draw Member, is the most complete Sinemurian part of the Sunrise Formation. The New York Canyon Member is also typically exposed at the entrance of the New York Canyon (Fig. 2-4; Fig. 2-5).   Period Stage Member Previous Designations  (Muller and Fergusom, 1939) Formation Jurassic Pliensbachian Mina Peak Js5 Sunrise Joker Peak Sinemurian New York Canyon Js4 Five Card Draw Js3 Ferguson Hill Js2 Hettangian Js1  Fig. 2-3 Lithostratigraphic units of Sunrise Formation and their ages at the Gabbs Valley Range, adopted from Muller and Ferguson (1939), Ferguson and Muller (1949), Taylor et al., (1983) and Taylor and Smith (1992).  13    Fig. 2-4 Tectonic setting of Five Card Draw, and location of studied sections. A. Lithologic assemblages of Oldow (1984), and mountain ranges of west-central Nevada numbered as follows, 1: Pine Nut Range, 2: Singatse Range; 3: Pilot Mountains, 4: Garfield Hills, 5: Gabbs Valley Range, 6: Shoshone Mountains, 7: Sand Springs Range, 8: Clan Alpine Mountains, 9: Stillwater Range, 10: Humboldt Range, 11: West Humboldt Range, (after Taylor and Smith, 1992); B: Locations of Five Card Draw (FCD) and New York Canyon in Gabbs Valley Range. FCD 1 & 2 are measured sections; the entrance of New York Canyon (NYC) is an unmeasured section.  C. Geologic map of Five Card Draw and New York Canyon area, after Ferguson and Muller (1949).  14    Fig. 2-5 Photographs of Five Card Draw and New York Canyon, Nevada. The measured sections (FCD 1 & 2) and lithologic units are labeled in the photos. Solid arrow lines indicate the traces of measured sections. White dash lines indicate the boundaries of stratigraphic units.   15    Fig. 2-6 Photographs of polished tuff samples collected from section FCD1, Five Card Draw Member. A. Sample A (between level 8 and 9). B. Sample B (above level 22). C. Sample C (between level 28 and 29).  16  The interval studied in this work includes the upper part of the Ferguson Hill Member, the Five Card Draw Member, and the lower part of the New York Canyon Member. The upper part of the Ferguson Hill Member (from basal Sinemurian to Involutum Zone) consists of dark gray cherty limestone and bluish gray bioclastic limestone, deposited in a high energy, shallow subtidal environment. The Five Card Draw Member (from Leslei Zone to Carinatum Zone) is typically fine-grained. Lithologically the member can be divided into 3 types: gray greenish siliceous siltstone and shale in the lower part, dark gray to black shale in the middle, and gray-greenish calcareous shale and siltstone in the upper part. Transitions between each lithology type are all gradual. The depositional environment is low energy, far offshore. The lower part of the New York Canyon Member (uppermost Carinatum Zone to lowermost Harbledownense Zone) mostly consists of blue to gray bioclastic limestone, deposited in a shallow subtidal environment. The interpretation of the depositional environment and paleobathymetry (Taylor et al., 1983) are based on the facies and the composite assemblage analysis of marine invertebrates developed by Taylor (1982). The paleobathymetry is consistent with the Sinemurian transgression-regression cycles in the eustatic curve proposed by Hallam (1981).  There are three possible tuff beds recorded in section FCD 1 in the shales of the Five Card Draw Member but non yield any zircons. All of these horizons are white or yellow in color, 0.5~2 cm thick, and exhibit sharp contacts within the shales. The detailed stratigraphic levels are illustrated in Chapter 3 Fig. 3-6. The first horizon (Sample A, Fig. 2-6 A) was collected near the base of the Five Card Draw Member (level 8 and 9 in of section FCD 1, Fig. 3-6), the second (Sample B, Fig. 2-6 B) near the middle of the unit (approximately 2 m above level 22 in FCD 1, Fig. 3-6) and the third (Sample C, Fig. 2-6 C) within the black shale interval (between level 28 and 29 in FCD 1, Fig. 3-6). Stanley (1971) recorded a white tuff unit in a minor sandstone bed composed of volcanic clastic fragments while re-measuring the type Sunrise Formation at New York Canyon. The tuff bed is within the siltstone and shale unit (Five Card Draw Member), 61 m (200 feet) above 17  the base of the Sunrise Formation is at a very similar level to the second tuff bed found in this work. Other tuff units are present, suggesting intermittent volcanic activity during the Early Jurassic in Nevada, however, Stanley (1971) indicated that the correlation between adjacent areas in Nevada was inconclusive.    In general, the study areas which are geographically distant from each other are distinct in tectonic history and depositional settings. The Last Creek Formation was deposited on an inactive, quickly subsiding magmatic arc while the Sunrise Formation was deposited in a platform setting on a relatively stable continental margin. The coeval deepening events in Last Creek (Castle Pass Member-Little Paradise Member transition) and Five Card Draw (Ferguson Hill Member-Five Card Draw Member transition) in the Early Sinemurian therefore suggest a probable eustatic influence. The comparison and contrast in the stratigraphy, ammonite fauna and geochemistry of the two study areas may enhance our understanding of the Sinemurian of the western Cordillera in North America and local paleontological or geochemical signals of the two separated areas may reflect some possible global events.  18  CHAPTER 3       BIOSTRATIGRAPHY AND BIOCHRONOLOGY  3.1  Introduction  The primary standard ammonoid zonation scheme for the Sinemurian of the Lower Jurassic was well documented by Dean et al. (1961), who summarized more than two hundred years of stratigraphic work in northwest Europe. There have been numerous subsequent refinements since then as summarized by Page (2003), in which the zones are referred to as ‘chronozones’ (standard zones). Although there have been attempts to apply the standard Northwest European zonation on a global scale (Blau and Meister, 2000; Meister, 2010), the effect of ammonite provincialism causes significant difficulties. Instead, the practice of using regional zonation schemes that are then correlated with the standard European zonation is more satisfactory.  The first ammonoid zone established for the Lower Jurassic of North America was the Canadensis Zone, proposed by Frebold (1967). Pálfy et al. (1994) proposed a local assemblage zonation from the uppermost Hettangian to lowermost Pliensbachian of Haida Gwaii (formerly Queen Charlotte Islands) in western British Columbia. The secondary standard Sinemurian zonation scheme for western North America was proposed by Taylor et al. (2001) based on successions in Sonora (northern Mexico), Oregon, Nevada and western BC (Pálfy et al., 1994), and was correlated with the primary zonation in Europe. Its applicability to elsewhere in western North America, particularly in the rest of Canada, is not well tested. This study is an attempt to investigate the applicability of the current Sinemurian zonation and to improve the zonation by incorporating the data from the new study areas.    The Last Creek Formation exposed in Taseko Lakes map area, British Columbia is one of the most fossiliferous and complete sequences for the Sinemurian, the data for which have not yet been included in the current western North American zonation. The 19  Sunrise Formation at Five Card Draw, Nevada is the most complete type section of the Sinemurian designated by Taylor et al. (2001). By comparing and correlating these two study areas, not only can we test the current zonation in both areas but also the data from Last Creek can be readily incorporated into the zonal scheme.   3.2  Sinemurian Zonation of Western North America The composite species range chart presented herein is based on data collected in this work (Fig. 3-1) but also includes data from the literature dealing with the same study areas (Smith, 1981; Macchioni et al., 2006). This range chart resembles that from (Fig. 3-2) for the originally proposed Sinemurian zonation (Taylor et al., 2001). According to their definitions, four zones of the Sinemurian can be recognized herein, namely the Involutum, Leslei, Carinatum and Harbledownense zones in ascending stratigraphic order.  The Jamesi Zone in the Upper Sinemurian in Taylor et al. (2001) cannot be recognized in this work. A discussion and revision at biozone level of the current Sinemurian ammonoid zonation for western North America is provided herein together with an updated correlation with the primary standard zonation in northwest Europe.   20    Fig. 3-1 Composite species range chart of Sinemurian of Last Creek, BC and Five Card Draw, Nevada. Taxa ranges primarily based on this work but also include Smith (1981) and Macchioni et al. (2006). Solid lines and dash lines mean actual and approximate ranges respectively.  21   Fig. 3-2 The original composite range chart for the Sinemurian of western North America (Fig. 7 of Taylor et al., 2001).  22  3.2.1  Abandonment of the Jamesi Zone The Jamesi Zone, as defined by Taylor et al. (2001), is only characterized by two taxa, Asteroceras jamesi and Asteroceras ocotilloi, occurring above Epophioceras and below the earliest echioceratid. The Jamesi Zone only occurs in Sonora, Mexico according to Taylor et al. (2001). This is problematic because firstly, erecting a zone that is only recognizable in the type section means that the zonation scheme cannot serve a biogeographical province or a large geographical region (the western Cordillera of North America in this case). Secondly, the reason why the Jamesi Zone cannot recognized elsewhere is not explained by Taylor et al. (2001). The fact that there is no disconformity in the Sinemurian successions in the US and Canadian study areas suggests it is probably due to paleobiogeographical and paleobioecological factors. Thirdly, there is a noticeable gap between the latest Epophioceras and the earliest oxynoticeratid and echioceratid in the zonation (Fig. 3-2) of Taylor et al. (2001), and the Jamesi Zone was erected to accommodate that interval as indicated in the definition. However, this gap does not appear to exist based on the data in this study (Fig. 3-1). In fact, the latest Epophioceras (Epophioceras cf. wendelli) almost co-occur with the earliest oxynoticeratids and echioceratids, which means the top of the Carinatum Zone is the base of the Harbledownense Zone and eliminates the necessity for the Jamesi Zone. Additionally, the Asteroceras jamesi, for which the zone was named, was synonymized with Euerbenites corinnae by Blau et al. (2002), and later Meister et al. (2005) even suggested that the Jamesi Zone should be changed to the Corinnae Zone. In Mexico, Euerbenites corinnae is one of the characterizing taxa of the Euerbenites horizon of an interval equivalent to the Upper Obtusum Zone in Europe (Meister et al., 2005).  Therefore the following revision of the zonation scheme is proposed: 1) remove the current Jamesi Zone and downgrade it to the Euerbenites horizon as part of the local zonation scheme for Mexico; 2) Include the Jamesi Zone interval into the redefined Carinatum Zone. 23     Fig. 3-3 A revised Sinemurian zonation for western North America and updated correlation with northwest Europe. The European zonation is extracted from Page  (2003). The North American zonation is modified from Taylor et al. (2001). The Hettangian-Sinemurian boundary is after of Longridge et al. (2006). Absolute ages of the stage boundaries are from Gradstein et al. (2012); the age of the Lower/Upper Sinemurian boundary is from Pálfy et al. (2000).   3.2.2  Revised definitions of the zones  Consequently, the revision of the current zonation requires that the current zones be redefined. The data from this work and recent literature make it possible to provide more refined definitions from the Involutum Zone to the lower part of the Harbledownense Zone of the Sinemurian of western North America (Fig. 3-3).  24   Involutum Zone Name-bearer: Coroniceras involutum TAYLOR, 1998. The Involutum Zone is characterized by various species of Coroniceras (C. cf. involutum, C. charlesi, C. cf. lyra, C. multicostatum, C. cf. mutabile), Tmaegoceras (T. crassiceps, T. cf. lates ulcatum, T. nudaries, T. obesus n. sp.), Tipperoceras (Tipperoceras mullerense, Tipperoceras n. sp. A), which are restricted to this zone, and also by earliest Arnioceras (A. arnouldi, A. ceratitoides, A. densicosta). The stratigraphically uncertain Fucinites sicilianus is found ex situ in this interval.   Leslei Zone  Name-bearer: Ectocentrites leslei (TAYLOR, GUEX & RAKÚS, 2001). The base of the Leslei Zone is marked by the last appearance of Tmaegoceras and Tipperoceras and large and strongly ribbed Coroniceras. Fossil occurrences in the lower part of the Leslei Zone are relatively rare but this part can be characterized by Arnioceras semicostatum, Arnioceras sp., and the long-ranging species of Arnioceras such as A. arnouldi and A. ceratitoides. The upper part of the Leslei Zone is characterized by abundant Ectocentrites leslei (Bartoliniceras leslei in Taylor et al., 2001; see Chapter 6 for synonymy) and Arnioceras miserabile, also by Arnioceras oppeli and Arnioceras n. sp. A. One specimen of Lytoceras sp. was found in association with Arnioceras miserabile.  Caenisites brooki and Caenisites turneri are restricted to the upper part of the zone. In addition, Macchioni et al. (2006) reported from Last Creek the presence of Procliviceras, Nevadaphyllites, Togaticeras, and Lytotropites in association with Caenisites.   Carinatum Zone  Name-bearer: Epophioceras carinatum SPATH, 1924. The base of the Carinatum Zone is marked by the first appearance of Asteroceras. The lowermost part of the zone is 25  characterized by the last appearance of Arnioceras miserabile and Ectocentrites leslei. The Carinatum Zone in general is characterized by abundant Epophioceras (E. carinatum, E. cf. wendelli), Asteroceras (A. cf. margarita, A. cf. varians) and Eparietites (Eparietites ex gr. impedens) which are all restricted to this zone, and also by the last appearance of the long ranging species of Arnioceras, including A. arnouldi, A. ceratitoides, A. densicosta. Noticeably, the ranges of the two cosmopolitan genera, Epophioceras and Asteroceras, are the same and both span the whole Carinatum Zone. This is in agreement with the same generic ranges in Europe and is also the basis for the revision of the Jamesi Zone.    Harbledownense Zone  Name-bearer: Paltechioceras harbledownense CRICKMAY, 1928. The base of the Harbledownense Zone is marked by the first appearance of Paltechioceras harbledownense. The lower part of this zone is characterized by abundant echioceratids (Paltechioceras harbledownense, Paltechioceras boehmi, Palaeochioceras cf. spirale), and rare oxynoticeratids (Oxynoticeras cf. simpsoni, Gleviceras ex gr. victoris) (Smith, 1981; Taylor et al., 2001), both of which are restricted to this zone.   3.3  Biostratigraphy of Measured Sections                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       3.3.1  Last Creek, British Columbia At the headwaters of Last Creek in Taseko Lakes map area, the Upper Hettangian and Sinemurian part of the Last Creek Formation are well exposed. The area is a structural window surrounded by thrust faults (Smith et al., 1998). The Sinemurian sequence within the window is also disrupted by minor faults. Therefore, two relatively complete sections were selected with the purpose of covering most of the Sinemurian above the sections measured by O’Brien (1985), which are the lowermost interval of the stage. The top and base of both sections are bounded by faults.  26   Last Creek (LC1) The section LC1 (Fig. 3-4) is adjacent to the creek at an elevation of 2219 m (see Appendix A), and spans from the calcareous sandstone beds of the uppermost Castle Pass Member to the calcareous siltstone and shale beds of the lowermost Little Paradise Member. This ~20 m interval is highly fossiliferous with well-preserved ammonites, bivalves, gastropods and rare brachiopods.  This section represents an interval from the Involutum Zone to the lower part of the Leslei Zone. The uppermost beds of the Castle Pass Member (level 01 to 05 in Fig. 3-4) yielded abundant Coroniceras. Earlier reconnaissance by the Geological Survey of Canada under the leadership of Dr. H. W. Tipper recorded Tmaegoceras, Tipperoceras, and Fucinites from this interval, which helps characterize this zone. The incoming of Arnioceras, which marks the beginning of the Leslei Zone, starts right above the sharp contact between the sandstone of the Castle Pass Member and the overlying shale of the Little Paradise Member (level 06 to level 10 in Fig. 3-4). Arnioceras semicostatum was collected ex situ from this interval.    27    Fig. 3-4 Biostratigraphy of section LC1 at Last Creek, British Columbia.   Last Creek (LC2) The section LC2 (Fig. 3-5) is west of the highest tributary at the head of Last Creek at an elevation around 2300 m (see Appendix A) and spans from the calcareous siltstone, calcareous shale unit to the overlying black shale unit of the lower part of the Little Paradise Member. This section is about 40 m thick, with well-preserved ammonites, bivalves and gastropods. Calcareous concretions of various sizes are common throughout the section and many of them contain well-preserved ammonites.  This section represents the Leslei Zone, and in particular the upper part of the zone. The lower part of the section has fairly sparse fossil occurrences, and is characterized by Arnioceras sp. and the long ranging Arnioceras ceratitoides.  28    Fig. 3-5 Biostratigraphy of section LC2 at Last Creek, British Columbia. Arrow and yellow line indicates a tuff bed.   By the examination of the fossils and by comparing the lithologic trends of the same 29  sequence described in Umhoefer and Tipper (1998), it is possible to deduce that this section is stratigraphically above that at LC1. The upper part of section LC2 is characterized by Arnioceras miserabile and Caenisites. Macchioni et al. (2006) reported Procliviceras, Nevadaphyllites, Togaticeras, and Lytotropites co-occurring with Caenisites from the same interval. Although not recorded in this study, specimens of Microderoceras, Xipheroceras, and Asteroceras found ex situ at the top of the section indicate the presence of the Carinatum Zone (Macchioni et al., 2006). Moreover, the presence of echioceratids (e.g., Echioceratidae gen. et sp. indet.) from the top of Last Creek in the collections of the Geological Survey of Canada indicates the presence of the Harbledownense Zone.    3.3.2  Five Card Draw, Nevada  The Five Card Draw in Gabbs Valley Range, Nevada is the type section for the Five Card Draw Member and one of the most complete Sinemurian sections in North America. The specimens collected from the upper part of the Ferguson Hill Member in Five Card Draw from Dr. P. L. Smith’s doctoral study are of particular interest, and thus are incorporated into section FCD1. The entrance of New York Canyon, approximately 1 km south of the mouth of Five Card Draw, was visited but not measured. It is also a well-exposed section that spans the upper part of the Five Card Draw Member and the New York Canyon Member. Several collections from localities at different levels within the Carinatum Zone were made.    30    Fig. 3-6 Biostratigraphy of Section FCD1 at Five Card Draw, Nevada. Arrow & yellow lines show localities of tuff beds. Tuff localities are labeled by letters.  Five Card Draw (FCD1)  The bioclastic limestone of the upper part of the Ferguson Hill Member (Fig. 3-6, 31  level 01 to 07) yields abundant, well-preserved ammonites, bivalves, brachiopods, corals and rare belemnites. Coroniceras, Tmaegoceras, Tipperoceras, and some early Arnioceras are found in this interval. The uppermost limestone beds of the Ferguson Hill Member mark the last appearance of Coroniceras and the incoming of a more diversified Arnioceras fauna. Therefore, the lithologic transition of the Ferguson Hill Member and the Five Card Draw Member is equivalent to the zonal transition from the Involutum Zone to the Leslei Zone.  As described by Smith (1981) and Taylor et al. (2001), the lower third of the Five Card Draw Member is a barren interval. The middle part of the member (Fig. 3-6, level 11 to 27) is highly fossiliferous, containing mostly ammonites and bivalves, many of which are compressed and preserved as external molds. Arnioceras miserabile and Ectocentrites leslei range throughout this interval. At level 27 (Fig. 3-6), the earliest Epophioceras carinatum and Asteroceras sp. co-occur with Ectocentrites leslei and Arnioceras miserabile, marking the beginning of the Carinatum Zone. Epophioceras and Asteroceras are common above this level (level 27 to 34, Fig. 3-6) but most of the specimens are less well-preserved. The rest of the Carinatum Zone in section FCD1 is not ideally exposed. The first Paltechioceras harbledownense was recorded approximately 5 m below the base of limestone beds of the New York Canyon Member, which marks the beginning of the Harbledownense Zone.   Five Card Draw (FCD2) Section FCD2 (Fig. 3-7), which is approximately 200 m east of section FCD1 at the head of Five Card Draw, has superior exposure to the equivalent part in section FCD1, and therefore is selected to better represent the Carinatum Zone and the lower part of the Harbledownense Zone. This section is about 40 m thick with dominated by ammonites with rare bivalves. The lower part of the section (Fig. 3-7, level 01 to 20) is assigned to the Carinatum Zone based on abundant Arnioceras and Epophioceras. Asteroceras, Eparietites 32  are also common but mostly poorly preserved. Ectocentrites leslei and Arnioceras miserabile were found ex situ below the base of the section, indicating the Leslei / Carinatum transition. The first Paltechioceras harbledownense occurs approximately 5 m (Fig. 3-7, level 20) below the massive limestone beds of the New York Canyon Member, indicating the base of the Harbledownense Zone. The lower part of the Harbledownense Zone is also characterized by Oxynoticeras and Gleviceras (Smith, 1981), Paltechioceras boehmi, and Palaeoechioceras cf. spirale.    Fig. 3-7 Biostratigraphy of Section FCD2 at Five Card Draw, Nevada.   33  3.4  Correlation and Biochronology  3.4.1  Correlation between Last Creek and Five Card Draw The biostratigraphic correlation of the measured sections is illustrated in Fig. 3-8, based on data described in Chapter 3.3. The sections FCD2, LC1 and LC2 are all correlated to section FCD1. The limestone unit at the base of FCD1 and the sandstone unit at the base of LC1 are both characterized by Tmaegoceras crassiceps, Tipperoceras mullerense and Coroniceras. The tops of both units are marked by the last appearance of Coroniceras, which is the top of the Involutum Zone. Therefore, the top of the Ferguson Hill Member is coeval with the top of the Castle Pass Member.  The dark grey to black shale unit in the middle third of section FCD1 is correlated with the calcareous shale to black shale unit in section LC2. Both are characterized by a diverse and abundant fauna of Arnioceras, particularly Arnioceras miserabile. One well-preserved specimen of Ectocentrites leslei is found in association with Arnioceras miserabile in the collection of the Geological Survey of Canada from Little Paradise Creek, approximately 5 kilometers east of Last Creek. This strengthens the assignment of this interval of the Little Paradise Member to the upper part of the Leslei Zone.  The greenish silty shale unit in the top third of the Five Card Draw Member and the brownish calcareous shale unit near the top of section LC2 are both characterized by the presence of Asteroceras within the Carinatum Zone, but the correlation line to section LC2 is postulated because no characterizing taxa are recorded in situ in Last Creek. This situation is similar to the situation with the Harbledownense Zone in Last Creek, where the stratigraphically uncertain position of the echioceratids means that the topmost mudstone unit in section LC2 can only be provisionally correlated with the topmost shale unit of the Five Card Draw Member and the lowermost limestone bed of the New York Canyon Member (lower part of the Harbledownense Zone).   34   Fig. 3-8 Biostratigraphic correlation between measured sections in Last Creek, British Columbia and Five Card Draw, Nevada. Dash lines show postulated correlations.  Arrow and yellow lines in the stratigraphic columns are ash beds.   3.4.2  Correlation with Northwest Europe  With the improvement in the definition and subdivision of the primary standard zonation of the Lower Jurassic of Europe (Page, 2003) and a more integrated dataset of the Sinemurian in western North America (e.g., Smith, 1981; Pálfy et al., 1994; Taylor et al., 2001; Macchioni et al., 2006; this work), an updated version of correlation with the standard zonation scheme from the Involutum Zone to the lower part of the 35  Harbledownense Zone is provided herein (Fig. 3-3).   Involutum Zone The Involutum Zone in western North America can be confidently correlated to the Bucklandi Subchronozone and the superjacent Lyra Subchronozone in Northwest Europe by the presence of Coroniceras multicostatum, Coroniceras cf. lyra, Coroniceras charlesi and the earliest Arnioceras arnouldi, Arnioceras ceratitoides, above the ranges of Metophioceras and Vermiceras. The presence of Tmaegoceras crassiceps in the study areas may indicate as low as the Rotiforme Subchronozone as suggested in Géczy and Meister  (2007).   Leslei Zone  The Leslei Zone in the western North America can be correlated to the remainder of the Semicostatum Chronozone (Scipionanum and Sauzeanum subchronozones) and the Turneri Chronozone. The lower part of the Leslei Zone is generally characterized solely by rare occurrences of Arnioceras. In fact, Dean et al. (1961) noted about the limited stratigraphic value of Arnioceras and the difficulty with its identification unless it is exceptionally well-preserved. Consequently, the biochronological constraints must be based on the well-characterized superjacent part of the Leslei Zone and subjacent Involutum Zone. The upper part of the Leslei Zone can be confidently correlated to the Turneri Chronozone in Northwest Europe by Caenisites brooki, Caenisites turneri, Caenisites pulchellus, and also by the relatively short-ranging Arnioceras miserabile.   Carinatum Zone  The Carinatum Zone in western North America is correlated with the Obtusum Chronozone in northwest Europe based on the presence of Epophioceras carinatum, Asteroceras cf. varians, Asteroceras cf. margarita, Xipheroceras and Eparietites. The 36  earliest Epophioceras co-occur with Caenisites in the Birchi Subchronozone in NW Europe (Page, 2003), whereas they are not found in co-occurrence in western North America. Therefore, the correlation of the base of the Carinatum Zone with the base of the Obtusum Zone is made with less confidence. The presence of Eparietites ex gr. impedens at the upper part of the Carinatum Zone suggests correlation with the Fowleri Biohorizon of the Denotatus Subchronozone (Upper Obtusum) in Europe since E. fowleri was synonymized to E. impedens by Dommergues et al. (2005).   Harbledownense Zone The lower part of the Harbledownense Zone in western North America is correlated to the Oxynotum and the lower part of the Raricostatum chronozones combined in Northwest Europe by the close incoming of both oxynoticeratids and earliest echioceratids, immediately above the ranges of the latest Epophioceras and Asteroceras (Smith, 1981; Taylor et al., 2001). Apart from the contradictory stratigraphic relationships of Paltechioceras and Palaeoechioceras in North America and Europe (see Chapter 6), the lower part of the Harbledownense Zone is most likely equivalent to the Oxynotum Chronozone and the superjacent Densinodulum Subchronozone (Lower Raricostatum) in northwest Europe based on the presence of Oxynoticeras, Gleviceras, and Crucilobiceras (Smith, 1981; Pálfy et al., 1994; Taylor et al., 2001).   37  CHAPTER 4       SEA LEVEL CHANGE AND AMMONITES  4.1  Introduction  The Early Jurassic is a time of significant eustatic sea level rise with several major transgressive pulses (Hallam, 1981). A general pattern of rapid and prominent sea level rises followed by stillstands or less prominent sea level falls is observed (Fig. 4-1). A series of major eustatic sea level rise and falls in the Jurassic has been recognized (Haq et al., 1987; Hallam, 1988). Some of those episodes are associated with widespread black shale deposition, bottom water anoxia, oceanic anoxic events (Jenkyns, 1988) or mass extinctions (e.g., Hallam and Wignall, 1999). It is in generally agreed that there is lack of evidence for Jurassic glacio-eustasy, and that eustatic change is related to plate tectonics (Hallam, 2001). Though more detailed causes of the Early Jurassic sea level changes remain poorly understood, volume changes in mid-ocean ridge systems and intraplate deformation could be the possible mechanisms (Immenhauser, 2007).  Eustatic rises, especially at times of intense rifting and continuing breaking up of the Pangaea (Golonka, 2007), may form new marine corridors or intermittent marine connections between formerly isolated oceans that then act as the pathways for the migration of marine organisms (Smith, 1983; Venturi et al., 2006). The radiation, extinction, and turnovers of ammonite fauna may reflect sea level changes (Hallam, 1988, 1990; O’Dogherty et al., 2000) because ammonites are highly susceptible to environmental instability (Sandoval et al., 2001). Besides, ammonites in basin margin sediments offer the best means of intercontinental correlation for the investigation of Jurassic eustatic changes (Hallam, 1978; Galloway, 1989).   There are two types of eustatic curves used as references for the Early Jurassic sea level change. One is proposed by Hallam (Hallam, 1978, 1981, 1988, 2001) based on a diverse criteria such as shallowing / deepening sequences, paleontology and 38  paleogeography. The other is proposed by the Exxon group (Vail and Todd, 1981; Haq et al., 1987, 1988) and based primarily on seismic stratigraphy of continental margins. Although the two types of curves differ in details to some extent, they coincide in the timing of many important eustatic events. The Sinemurian part of both types of curves are highly similar and the eustatic events proposed by Hallam (Hallam, 1978, 1981, 1988) are also recorded in the Exxon curve (Haq et al., 1987, 1988).     Fig. 4-1 Eustatic curves for the Early Jurassic plotted against periods of black shale deposition (shown in grey bands). Curve a is from Hallam (1988), curves b and c are from Haq et al. (1987). Black shale deposition and possible OAE (oceanic anoxic events, shown in black bands) is from Jenkyns (1988), based on continental Europe. The proposed eustatic changes in Sinemurian are marked as T1 (Early Sinemurian transgression), R1 (mid-Late Sinemurian regression) and T2 (Late Sinemurian transgression).   Hallam (1981, 1988) proposed three eustatic events during the Sinemurian which 39  are labeled in Fig. 4-1 as T1: Early Sinemurian transgression (Semicostatum Zone); R1: Mid-Late Sinemurian regression (Late Obtusum Zone to Early Oxynotum Zone); T2: Late Sinemurian transgression (Late Oxynotum Zone to Early Raricostatum Zone). These events mirror the eustatic curve of Haq et al. (1987) from which the estimated amounts of eustatic changes can be measured: T1 ≈ 50 m; R1 ≈ 20~30 m; T2 ≈ 30 m. With the help of the refined Sinemurian ammonoid zonation, the sections from Last Creek and Five Card Draw are valuable for testing the proposed hypotheses concerning eustatic sea level changes during the Sinemurian.     4.2  Sea level change in study areas   To eliminate possible confusion, it is necessary to first clarify the concepts related with sea level change used in this chapter. The concept of eustasy or eustatic sea level, first introduced by Eduard Suess in 1888 and translated to English by Sollas in 1906, refers to any uniformly global change of sea level that might reflect the change in the total volume of the water in the ocean or the change in the shape and capacity of the ocean basins. Local (or relative) sea level refers to the distance from sea surface to the local moving datum (the top of the local lithosphere). Water depth refers to local sea level minus the thickness of sediments. Transgression and regression are defined as the landwards or seawards migrations of the shoreline respectively (Catuneanu, 2006). Coeval transgressive or regressive sequences across continents may suggest eustatic control (Hallam, 1981).   4.2.1  Last Creek, British Columbia The Last Creek Formation is recognized as a fining-upwards sequence that grades from nearshore conglomerate and sandstone into inner shelf sandstone in the Lower Sinemurian and then into outer shelf to slope siltstone and shale in the rest of the Sinemurian (Umhoefer, 1990). The local sea level change recorded in sediments is usually 40  a combination of multiple factors, including eustatic change, local subsidence, water depth and sedimentation (van Wagoner et al., 1990). The effects of subsidence and sedimentation may increase, counterbalance or reverse those of eustatic changes (Hallam, 1981). The nature of the magmatic arc setting of the Cadwallader terrane requires consideration of the tectonic history and depositional environments and their influence upon the local sea level change as it interacts with eustatic fluctuation. Herein the accommodation space equation (van Wagner et al., 1990) is adopted to quantitatively analyze the possible eustatic changes recorded in Last Creek.   The original equation: T + E = S + W  where T: rate of tectonic subsidence;  E: rate of eustatic sea level rise;  S: rate of sedimentation (corrected for compaction);  W: rate of water depth increase.   The amount of eustatic change can be expressed as:    ΔE = ΔS + ΔW - ΔT                                   equation (1)  where Δ represents the amount of change of each variable during a given length of time. This equation can be used to calculate the eustatic change based on the data from this study area and compare with the proposed eustatic changes (Haq et al., 1987; Hallam, 1988) to see if there is any consistency. The following examples are the applications of this method to investigate the 3 proposed eustatic changes in Sinemurian in Last Creek, in conjunction with lithological and depositional facies analysis.  41   Early Sinemurian transgression (T1) The coarse-grained clastic unit in the upper part of the Castle Pass Member is overlain by the fine-grained unit in the lowermost part of the Little Paradise Member through a sharp lithologic contact which has been previously documented by Umhoefer (1990), Smith et al. (1998) and Umhoefer and Tipper (1998). This local transgressive surface corresponds with the Involutum-Leslei transition and is consistent with the Early Sinemurian eustatic rise T1 (Fig. 4-1).  The duration of this cycle of eustatic rise is approximately equivalent to that of a European ammonite zone (the Semicostatum Zone), the average duration of which is 1.4 Myr for the Sinemurian (6 zones in 8.5 Myr of time; age data after Gradstein et al., 2012). The amount of the proposed eustatic rise (noted as ΔEp) during the Early Sinemurian transgression is about 50 m, which is a significant amount comparing to the average eustatic rise of 8 m per zone for the Sinemurian (measured from the eustatic curve in Haq et al., 1987). In the Cadwallader terrane, the arc-related volcanism terminated in the early Norian in Late Triassic (Rusmore, 1987) followed by a long-term thermal subsidence until the beginning of the Middle Jurassic (Umhoefer and Tipper, 1998). In this case, the effect of thermal subsidence (noted as ΔTa) and tectonic subsidence (ΔTb) must both be taken into account for the calculation of total subsidence (see Table 4-1). The deposition of the Last Creek Formation spans approximately 30 Myr from Late Hettangian to the Early Bajocian (Gradstein et al., 2012).With the data published in Umhoefer (1990) and Umhoefer and Tipper (1998), the average rate of subsidence and the total amount of subsidence can be calculated (see Table 4-1), assuming the rates of thermal subsidence and tectonic subsidence are both stable in a short period of time (a few Myr). In order to shift the depositional environment from near shore to outer shelf (Fig. 4-2 A) to account for the local transgressive event happen, an approximate 100 m rise in water depth (ΔW) is required (Umhoefer and Tipper, 1998).  42   Fig. 4-2 Early Sinemurian transgression recorded in Last Creek, British Columbia (section LC1). A. Lithology, depositional environment and paleobathymetry of the Castle Pass-Little Paradise transition. Depositional environment and paleobathymetry are from Umhoefer and Tipper (1998). B. Photograph of section LC1. The strata are dipping into the slope towards northwest.  43  All values of the variables of equations (1) are listed in Table 4-1. The calculated eustatic sea level rise (ΔE) is:   ΔE = ΔS + ΔW - (ΔTa + ΔTb) = 52 ~ 59 m   Table 4-1 Estimation of the controlling factors of local sea level change and their contributions to Early Sinemurian transgression in Last Creek.  Controlling Factors Amount (m) Duration (Myr) Rate (m/Myr) Δ (in 1.4 Myr) Source ΔTa: Thermal subsidence during the deposition of Last Creek Formation 1000 30 33 46 Umhoefer (1990) ΔTb: Tectonic subsidence during the deposition of Last Creek Formation 35-50% of ΔTa 30 35-50% of ΔTa 16 ~ 23 Umhoefer and Tipper (1998) ΔEp: Proposed eustatic rise during the Semicostatum (Early Sinemurian).  50 1.4 36 50 Haq et al. (1987) ΔS: Thickness of Last Creek Formation and average sedimentation rate (minimum value) 450 30 15 21 Umhoefer and Tipper (1998) ΔW: water depth rise from nearshore to outer shelf    100 Umhoefer and Tipper (1998)  Although there might be errors because the thermal subsidence rate is the minimum estimation (Umhoefer and Tipper, 1998), and there are missing strata at the erosional unconformity at the top of the Last Creek Formation, this result is strikingly close to the proposed amount of eustatic rise during this transgression (ΔEp in Table 4-1) which is approximately 50 m.  Collectively, the Early Sinemurian transgression recorded at Last Creek is a combination of eustatic rise, thermal subsidence, tectonic subsidence and sedimentation. The rapid eustatic rise contributed approximately 50 m (40%) of this transgression, without which the shift of the depositional environments from near shore to outer shore is not possible.    44  Mid-Late Sinemurian regression (R1) The data from Last Creek that can contribute to our understanding of the mid-Late Sinemurian regression (R1) and the Late Sinemurian transgression (T2) is relatively limited. The steady subsidence lead to the gradual deepening of the depositional environment from outer shelf to slope, the paleobathymetry of which is approximately 150 to over 200 m (Umhoefer and Tipper, 1998), while the amount of eustatic fall is about 20~30 m (ΔEp, measured from Haq et al., 1987). Unlike eustatic rise, a eustatic fall needs to be more significant to counterbalance the effect of subsidence and leave discernible records in the sediments in a marine setting. According to Umhoefer and Tipper (1998), the paleobathymetry basically remains unchanged (or increased very slowly) during Late Sinemurian. Therefore, as a conservative estimation, ΔW approximately equals zero. Assuming the duration of the proposed regression is also 1.4 Myr (from Late Obtusum Zone to Early Oxynotum Zone) and all other variables remain the same, a similar calculation can be made:   ΔE = ΔS + ΔW - (ΔTa + ΔTb) = - 41 ~ - 48 m   This result suggests a eustatic sea level fall by 41 to 48 m which is a relatively more significant compared to the proposed value (ΔEp = 20~30 m) but still within the same magnitude. Lithological changes also support the occurrence of a regression. Some ex situ specimens of Asteroceras from Last Creek are preserved in poorly cemented and fairly sandy concretions while the sediments of underlying Leslei Zone are mostly black shale to calcareous siltstone. This indicates the Carinatum Zone fossils are preserved in coarser sediments than that of the Leslei Zone and the presence of a coarsening-upward sequence during the Carinatum Zone (equivalent to Obtusum Zone in Europe) in Last Creek.  Although there is a lack of sufficient evidence in Last Creek for the mid-Late Sinemurian regression (R1) it could be indicated by lithological changes in the fossil 45  specimens of the upper part of the Leslei Zone and the Carinatum Zone. The result from accommodation space equation also suggest the presence of a eustatic fall without which another deepening upwards sequence is likely to have occurred.   Late Sinemurian transgression (T2) The amount of eustatic rise during the proposed Late Sinemurian transgression (T2) is about 30 m (ΔEp ≈ 30 m, Haq et al., 1987). The duration of this cycle is equivalent to the Raricostatum Zone in Europe (1.4 Myr). The increase in water depth may be several tens of meters up to one hundred meters as the depositional environment was gradually shifting to the slope. Therefore a conservative estimation of 30 m is assigned to ΔW. Assuming the other variables of the sea level equation remain stable as in Table 4-1, a similar calculation for the Late Sinemurian transgression (T2) in Last Creek is as follows:   ΔE = ΔS + ΔW - (ΔTa + ΔTb) = -9 ~ -18 m   This result suggests a eustatic sea level fall by 9 to 18 m which is significantly different with the proposed eustatic rise (ΔEp ≈ 30 m; Haq et al., 1987). The reasons for this may be: a. A sudden increase in sedimentation rate (S);  b. A reduced rate of subsidence (Ta & Tb); c. An error in the estimation of the increase in water depth (ΔW).  It is possible that sedimentation rate increased suddenly but only to a limited amount. A difference of ~ 40 m in 1.4 Myr requires the sedimentation rate to double which is less likely to happen in shale and siltstone facies in an outer shelf to slope environment. As mentioned earlier, the assumed subsidence rate is already taken at the minimum estimate (it could be as high as 50 m/Myr) which makes it less likely to be a factor. The only reasonable cause is likely the underestimation of increasing water depth. In fact, the 46  echioceratid-bearing rocks (Harbledownense Zone) from Last Creek are mostly well-cemented, gray to dark grayish calcareous mudstone. These mudstones are generally massive with very rare fine laminations. The finer sediments are distinct from the underlying Carinatum Zone although details of the lithological variations in this sequence are not available.   Therefore the fining-upwards sequence in Harbledownense Zone in Last Creek can possibly suggest a transgressive event which is consistent with the proposed Late Sinemurian transgression (T2), though the accommodation space equation failed to reflect this, due to large errors in the estimation of water depth increase.   Table 4-2 Composite faunal assemblages of marine invertebrates and depositional environment (after Taylor, 1982). Composite Assemblage Assemblage Characterization Depositional Environment A Epifaunal-dominated; brachiopod abundant; low diversity in siphonate feeders  Intertidal to sublittoral, high energy B Diverse, bivalve-dominated; gastropods and bivalves with large, onate and thick shells; ammonites uncommon Shallow subtidal, moderate to high energy C Overlap of diverse bentho shelly fauna and ammonites or ‘offshore’ bivalve Offshore D Ammonites, nautilids, belemnites and ‘offshore’ bivalves Further offshore  4.2.2.  Five Card Draw, Nevada The Upper Triassic to Lower Jurassic strata in the Gabbs Valley Range were deposited in a back-arc basin with a volcanic arc to the west and the North American continent to the east (Oldow, 1984; Gradstein et al., 2012). It is suggested that the Early Jurassic Sunrise Formation in the Gabbs Valley Range has the shallowest platform setting in the southeastern part of the basin, as described in Taylor et al. (1983). Although quantitative data on the subsidence history is not available for this area, and the same calculations using the accommodation space equation cannot be made for comparison with Last Creek. The rate of subsidence of the continental margin is probably considerably lower 47  than that of the magmatic arc in Last Creek. In addition, the complete lithological changes within the measured sections (FCD1 & FCD2), precise ammonoid biostratigraphy and paleobathymetry reconstruction (Table 4-2; Taylor et al., 1983) allow direct comparison with the proposed eustatic curves of Haq et al. (1987) and Hallam (1988).   Early Sinemurian transgression (T1) In Five Card Draw, an Early Sinemurian transgressive event is recorded by the sharp contact (Fig. 4-3) between the top of the limestone of the Ferguson Hill Member (Involutum Zone) and the siltstone and shale at the base of the overlying Five Card Draw Member (Leslei Zone). The fairly resistant bioclastic limestone weathers blue-brownish, while the siltstone and shale are light greenish and more easily eroded which makes the contact rather distinct (Fig. 4-3 B). In addition, the shift in the composite assemblages of marine invertebrates from B to C (Table 4-2; Fig. 4-3 A) indicates a change in the depositional environment from shallow subtidal zone to offshore which is approximately some tens of meters deeper (Holland, 2012) within a platform setting. This transgressive event correlates with the Early Sinemurian transgression (T1) in both timing and amount (~50 m, Chapter 4.2.1).   48   Fig. 4-3 Early Sinemurian transgression recorded in Five Card Draw, Nevada (section FCD1). A. Lithology, depositional environment and paleobathymetry reconstructed by composite assemblages of marine invertebrates (Taylor, 1982) of Ferguson Hill-Five Card Draw transition. Depositional environment and paleobathymetry are from Taylor et al. (1983). B. Photograph of Ferguson Hill-Five Card Draw transition. The strata are dipping towards the left (south) in the photo.   49   Mid-Late Sinemurian regression (R1) The upper part of the Five Card Draw Member (Carinatum to lower Harbledownense Zone) is a slowly fining upwards sequence. The lithology gradually changes from finely laminated black shale at the lower part to gray greenish shale and silty shale in the upper part. There is a sharp contact (Fig. 4-4) between the top of the shale beds of the Five Card Draw Member (lowermost Harbledownense Zone) and the basal limestone of the overlying New York Canyon Member (Harbledownense Zone), indicating a regressive event. The regressive surface (Fig. 4-4 B) is distinguished by the poorly weathered shale beds overlain by the resistant light gray to brownish (when weathered) limestone. The depositional environment shifts back to shallow subtidal from offshore, as indicated by the change in the composite faunal assemblages (Fig. 4-4 A).  There is also evidence for a hardground surface recorded at 3.7 m above the base of the New York Canyon Member exposed in New York Canyon. Hematite-infilled boreholes occur that are assigned to the ichnogenus Trypanites of the Trypanites ichnofacies (Smith, 1981). This can indicate a water depth as shallow as composite assemblage A which may be equivalent to the shallowest point during the deposition of the Ferguson Hill Member. The regressive surface occur at the lower part of the Harbledownense Zone, which is correlated with the Oxynotum Zone in Europe. This surface corresponds to the mid-Late Sinemurian regression in the eustatic curve of Hallam (1981), as suggested in Taylor et al. (1983). Consistency is also found in both of the updated eustatic curves (Fig. 4-1) of Hallam (1988) and Haq et al. (1987). By comparing the changes in paleobathymetry, the amount of this regression is equivalent to the amount of the Early Sinemurian transgression in Five Card Draw which appears to be more than the mid-Late Sinemurian regression (R1).   50    Fig. 4-4 Mid-Late Sinemurian transgression recorded in Five Card Draw, Nevada (section FCD2). A. Lithology, depositional environment and paleobathymetry indicated by composite assemblages of marine invertebrates (Taylor, 1982) of Five Card Draw-New York Canyon member transition. Depositional environment and paleobathymetry modified after Taylor et al. (1983). B. Photograph of Five Card Draw-New York Canyon transition. The strata are dipping towards the left (south) in the photo.   51  Late Sinemurian transgression (T2) The Harbledownense Zone (Late Sinemurian) is not fully recorded in the measured sections in Five Card Draw in this study and therefore data from the literature are used to investigate a possible transgressive event in the Upper Sinemurian. The New York Canyon Member in the upper part of the Sunrise Formation spans most of the Harbledownense Zone except for the basal part. It is a predominantly composed of limestones deposited in a shallow subtidal setting. The measured sections of Smith (1981) in the Gabbs Valley Range include this interval but no transgressive sequence unit is recorded. However, Taylor et al. (1983) recorded a minor transgressive event by the presence of a relatively thin shale unit in the lower part of the New York Canyon Member. This minor deepening occurs within the Harbledownense Zone, following the mid-Late Sinemurian regression (R1). The stratigraphic level is consistent with the Late Sinemurian transgression (T2) but the amount of local sea level rise may only be fraction of that of the eustatic rise. Therefore the proposed Late Sinemurian transgression (T2) is possibly recorded in Nevada but its effect might have been diminished by local factors.   4.3  Sea level change and ammonoid diversity  The influence of eustatic change upon marine invertebrates and their biodiversity has long been recognized and discussed (e.g., Hallam, 1987; McRoberts and Aberhan, 1997; Ruban, 2007). The marine biotic turnovers (radiation, origination and extinction) are thought to reflect eustatic fluctuations (e.g., Hallam and Cohen, 1989). It has been suggested that during times of eustatic sea level rise, there will be an increase in habitable area, niche diversity, environmental stability as well as immigration of new species. This should increase marine biodiversity whereas eustatic fall should have the reverse effect (e.g., McRoberts and Aberhan, 1997). Marine invertebrates are commonly used for studying environmental change and evolution. Ammonites were more sensitive to small 52  changes in the stability of their habitat than most other invertebrate groups and they show higher rates of evolutionary turnover (e.g., Hallam, 1990). The relationships between the biodiversity of Early to Middle Jurassic ammonites and eustatic sea level changes have been investigated in north Asia (Meledina et al., 2005) and in Spain for the whole Jurassic by O’Dogherty et al.  (2000) and Sandoval et al. (2001). All these studies show a fairly good correlation between diversity change, faunal turnover and eustatic fluctuation. In this section, the methodology in O’Dogherty et al. (2000) is adopted to visualize the ammonite diversity changes during the Sinemurian of Last Creek and Five Card Draw in relation to the eustatic sea level changes (Fig. 4-5).    Fig. 4-5 Eustatic fluctuations and ammonite diversity in the study areas. Paleobiodiversity is primarily based on this work, but also includes data from literature (Umhoefer and Tipper, 1998; Taylor et al., 2001; Macchioni et al., 2006). “+” means total number of originations per zone; “-” means total number of extinctions per zone. The Sinemurian eustatic curve a is adapted from Hallam (1988), b and c (short term and long term respectively) are from Haq et al. (1987).   The biostratigraphic and taxonomic data (including preliminary taxonomic work) of the Sinemurian fauna are primarily based on this work (Chapter 3 and 6) but also 53  incorporate some data from the literature on the Cadwallader terrane (Umhoefer and Tipper, 1998; Macchioni et al., 2006) and west-central Nevada (Smith, 1981; Taylor et al., 2001), all of which are compiled and listed in Appendix B. The Sinemurian ammonoid zonation uses the revised zonation for western North America in this work, in order to have a more accurate data sample from two domains at comparable sizes, rather than two sections. There are a total of 27 genera and 56 species recorded form Cadwallader terrane, 19 genera and 59 species from west-central Nevada. The numbers of total genera, species, originations and extinctions of the ammonite taxa per zone are plotted against the eustatic curves (Haq et al., 1987; Hallam, 1988) from the Involutum Zone to the lower part of the Harbledownense Zone (Fig. 4-5).  In the Cadwallader terrane, British Columbia, the ammonite diversity at both genus and species levels start at intermediate values at the Involutum Zone and reaches maxima (13 for genus, 32 for species) at the middle of the Leslei Zone. After that, the diversity at both taxonomic levels decreases in the Carinatum Zone and the lower part of the Harbledownense Zone. The amount of faunal turnover at the genus level is the highest at the Involutum Zone then decreases stage by stage, while at the species level it reaches the peak value in the Leslei Zone. The Leslei Zone also records the maximum value for species origination. The most noteworthy phenomena is that the diversity maxima in the Leslei Zone corresponds with the Early Jurassic transgression (T1), which is also recorded by O’Dogherty et al. (2000) and Sandoval et al. (2001) in the fauna of the Tethyan Realm.  In west-central Nevada, the ammonite diversity at the genus level remains quite stable during the Sinemurian with only a very slight increase in the Carinatum Zone. This slight increase in diversity is amplified about 3 times in the species level with a peak value of 21 in the Carinatum Zone. The amount of faunal turnover at the genus level is also quite stable during the Involutum and Leslei zones, followed by a slight increase in the Carinatum Zone where it reaches a maximum followed by a decrease of about 30% in the lower part of the Harbledownense Zone. This pattern of faunal turnover is mirrored at the 54  species level but differs in that the number of species originations is fairly high at the Involutum Zone, decreases in the Leslei Zone and then rises to the peak value at the Carinatum Zone. There is hardly any correlation between eustatic sea level change and Early Sinemurian ammonite diversity. In the Late Sinemurian, the diversity maxima seems to correspond with the mid-Late Sinemurian regression which is well-represented in the Sunrise Formation in Five Card Draw. The diversity and faunal turnover maxima in the Carinatum Zone is consistent with the data of O’Dogherty et al. (2000) and Sandoval et al. (2001), which show a small peak in both diversity and faunal turnover during the Obtusum Zone but less significant than the Early Sinemurian maxima.  The co-occurrence of the maxima of ammonite diversity and faunal turnover in both Cadwallader terrane and Spain (O’Dogherty et al., 2000) during the Leslei Zone (Semicostatum-Turneri) as well as the Early Sinemurian transgression (T1 in Fig. 4-5) suggests a eustatic control. This co-occurrence also corresponds to the gradual positive carbon isotope excursion (CIE) in the late Early Sinemurian which is most likely driven by a global increase in primary productivity (see Chapter 5). The same co-occurrence is not reflected in west-central Nevada, which may be due to preservation or ecological factors. The lower half of the Leslei Zone in the Sunrise Formation in Nevada is a barren interval and therefore the data collected might reflect only a portion of the true diversity. The barren interval may also result from lack of favorable living conditions for the marine organisms.  It must be noted that the data of the Carinatum Zone and the Harbledownense Zone in Cadwallader terrane are insufficient and probably much lower than the true diversity, which hinders the validity of correlation with eustatic change. If an increase in the marine biodiversity can reflect eustatic rise and a decrease can reflect eustatic fall, the increase in diversity in both west-central Nevada and Spain during the Carinatum Zone (mid-Late Sinemurian regression) contradicts this hypothesis. The Carinatum Zone of the Sunrise Formation in Nevada is a slowly shallowing upwards sequence. The densely spaced fossil occurrences along section FCD2 may suggest favorable preservation or ecological 55  conditions which outbalanced the effect of a relatively minor eustatic fall. In Spain, this coeval increase in biodiversity and faunal turnover seems to have been driven by a steady local sea level rise in the late Sinemurian (Vera, 1988; O’Dogherty et al., 2000). Thus the diversity and faunal turnover increase during mid-Late Sinemurian in west-central Nevada and Spain correspond approximately with each other, but are likely due to different local factors.  It is observed in the northwest Tethys (O’Dogherty et al., 2000; Sandoval et al., 2001) that the diversity and faunal turnover of the Jurassic ammonites as a whole reflect all the major eustatic changes. Similar patterns are also observed in the late Early Jurassic and early Late Middle Jurassic in Siberia (Meledina et al., 2005), but the diversity seems to show a certain lag in response to eustatic change and it also seems to be related to the variations of paleotempetarure. McRoberts and Aberhan (1997) suggest there might be a complex relationship between marine diversity and eustatic changes and some other interrelated factors, including the tempo of eustatic changes, topographic relief, and the size and paleogeography of the continents. Similarly, Holland (2012) also argued that the habitable space in shallow water is not a simple function of sea level.  To sum up, in the Cadwallader terrane, the Early Sinemurian transgression (T1) is possibly a major driving force of influencing the diversity and faunal turnover maxima in the Leslei Zone. The insufficiency of taxonomic data limits our understanding of the relationships of ammonite diversity and the mid-Late Sinemurian regression (R1) and Late Sinemurian transgression (T2). In west-central Nevada, the ammonite diversity is basically not affected by eustatic changes at all, probably due to special conditions of local ecology, environment or preservation. In general, broad patterns of the ammonite diversity show good correlation with eustatic fluctuations (e.g., O’Dogherty et al., 2000; Meledina et al., 2005). The changes in diversity and faunal turnover at small scales (zone level) are usually the result of multiple factors, including eustatic changes, and therefore need to be interpreted on a case by case basis.   56  CHAPTER 5       GEOCHEMISTRY  5.1  Introduction   Understanding marine sedimentary rocks and their depositional environments throughout geological time allows us to evaluate past changes in ocean chemistry. The ability to recognize these variations, at both the localized and global scale, enables us to trace temporal alterations in the balance of inputs to the global oceans. To do this, geochemical tracers such as carbon and osmium (Os) isotopes are utilized. Carbon isotope profiling enables us to detect variations in primary productivity (Hesselbo et al., 2000), together with periods of increased bottom-water upwelling, and widespread oxidation of organic matter during eustatic sea level fall (Jenkyns et al., 2002). Osmium isotopes allow tracing of inorganic fluxes into the marine environment, by recording the effects of meteorite impacts, continental weathering, and volcanogenic fluxes (Cohen et al., 1999; Peucker-Ehrenbrink and Ravizza, 2000).  The Jurassic Period witnessed major tectonic events that significantly impacted the global environment; most notably the global tectonic plate reorganization associated with the break-up of Pangaea. Early Jurassic Pangaean fragmentation into Laurasia and Gondwana established new seaways and marine connections and was accompanied by a steady rise in sea level (Hallam, 1981). This complex and dynamic tectonic period was also associated with significant fluctuations in global ocean chemistry (Cohen et al., 1999; Hesselbo et al., 2000; Cohen and Coe, 2007; Jenkyns, 2010; Jenkyns and Weedon, 2013; Porter et al., 2013; Riding et al., 2013) resulting from a number of factors including increased tectonism.  The identification of global carbon isotope excursions (CIEs) throughout geological time significantly improves our ability to conduct temporal correlations of marine and continental successions. In addition, fluctuations in the marine stable carbon isotope record, 57  on a localized and global scale, enable the recognition of changes in ocean chemistry and the evaluation of variations in the balance of inputs to the global oceans through time. A number of previous workers have recognized oceanic carbon isotope excursions (CIEs) during the Early Jurassic, as both global and smaller-scale events. Widespread attention has been given to the negative CIE during the Early Toarcian oceanic anoxic event (T-OAE at ∼182 Ma; Hesselbo et al., 2000; Cohen and Coe, 2007; McArthur et al., 2008; Jenkyns, 2010; Caruthers et al., 2011), that is hypothesized to have resulted from the release of 12C-enriched methane accumulated below the seafloor  (Hesselbo et al., 2000; Cohen and Coe, 2007). Other negative CIEs have also been reported across both the Pliensbachian-Toarcian boundary (Hesselbo et al., 2000) and the Sinemurian-Pliensbachian boundary  (Korte and Hesselbo, 2011). However, until recently the Sinemurian time interval has remained poorly understood. Work in the UK (Jenkyns and Weedon, 2013; Riding et al., 2013) has highlighted carbon isotope anomalies in the Sinemurian marine and terrestrial records, but it is not clear from these investigations whether or not these anomalies represent a global signal.  Herein, we present high-resolution carbon isotope data for Sinemurian marine sections from Five Card Draw, Nevada, USA (Taylor et al., 1983, 2001) and Last Creek, British Columbia, Canada (Smith et al., 1998; Umhoefer and Tipper, 1998; Smith and Tipper, 2000; Macchioni et al., 2006) in order to determine whether a global carbon isotope signal can be identified during the Sinemurian. In addition, osmium isotope data is used to quantitatively evaluate differences between the depositional environments of these two North American regions, allowing us to assess how the depositional realm can influence the recording of isotopic anomalies in the stratigraphic record. The biochronologic constraints are provided by the data presented in Chapters 3 and 6. The sampling methodology and analytical protocol are introduced in Appendix C.   58  5.2  Analytical results   5.2.1  Total Organic Carbon (TOC) and δ13Corg Measured bulk TOC and δ13Corg data for the Five Card Draw samples are presented in Fig. 5-1. The TOC concentration is consistently low for both FCD1 and FCD2 sections, with all samples (apart from one) falling within the range of 0.03-2.77 wt%. The only exception to this is sample FCD1-095 (16.57 wt% at 38.5 m). Aside from this and some minor peaks up to ∼1.70 wt%, TOC values in FCD1 are relatively consistent (average value of 0.31 wt.%) until ∼73 m, where the TOC profile becomes more erratic (average value of 0.8 wt.%). The variability noted here is also reflected in the 0-20 m interval of the FCD2 section (average of 0.78 wt%). However, from 20-28 m little variability is observed in the TOC values (0.06-0.33 wt%).  In FCD1, δ13Corg values range from -22 to -26‰. In the lowest part of the section (0-20 m), a gradual shift to more negative δ13Corg values is observed, with an average value of -23.85‰. For the remainder of the Leslei Zone (∼20-73m), δ13Corg values are relatively consistent with an average value of -25.82‰. Following this, a slight rise in δ13Corg (∼1‰) is noted in the Carinatum Zone (∼73-100m). The δ13Corg data for FCD2 is comparable to that of FCD1, with a range from -23.10 to -26.10‰ and an average of -24.92‰. The gradual 1‰ positive shift in the Carinatum Zone seen at FCD1 is also observed in this section.  Total organic carbon and δ13Corg data for the Last Creek sections are presented in Fig. 5-2. The TOC concentration is generally low in all samples for both LC1 and LC2 sections, ranging from 0.01 to 3.05 wt% and from 0.18 to 2.10 wt%, respectively. Little fluctuation is observed in the lowermost part of LC1 (0-10 m), with all values falling within the range of 0.10-0.86 wt%. Greater variation is seen from 10 to 17m in LC1, with TOC concentrations of 0.32-3.05 wt%. This variation continues into the base of LC2 (0-8m; 0.18-2.10 wt%). Over the 13-20 m interval within LC2, the TOC values decrease from 1.80 59  to 0.65 wt%, before becoming relatively consistent for the remainder of the section (20-38 m), with an average value of 0.65 wt%.     Fig. 5-1 Total Organic Carbon, δ13Corg, and Re-Os isotope profiles for FCD1 and FCD2  The δ13Corg data for LC1 falls within the range of -23.28 to -26.28‰. There is an initial negative peak at the base of the section (-26.28‰; 0.3m). Following this, δ13Corg values maintain an average of -24.59‰ from 0.9 to 10m, before shifting to more negative 60  values (average of -25.35‰; 10-13m). At ~13.9 m there is a prominent positive shift to -23.28‰, with a subsequent return to values that average -25.57% for the remainder of the LC1 section.  At the base of LC2 (0-2m) δ13Corg values average -26.89‰, before shifting to more positive values from ~3-13 m with an average value of -25.89‰. A positive shift to -24.66‰ is also observed within this interval at 6.6m. Following this, the data gradually shifts from -25.52‰ (13.5m) to -23.66‰ (28.6m). A prominent negative excursion, averaging -26.53‰, is observed over a 4.2m interval at 28.9-33.1m. At 33.1m, the carbon isotope values immediately return to an average of -23.95‰ for the remainder of the section; comparable to values prior to the negative excursion (-23.90‰; 25-28.9m).   5.2.2  Rhenium and osmium abundance and isotope data All measured Re and Os abundances and isotopic compositions for the Five Card Draw and Last Creek sections are presented in Table 5-1, Fig. 5-1 and Fig. 5-2, respectively.  Rhenium and osmium abundances for samples from Five Card Draw range from ∼1.5 to 57 ppb and from ∼74 to 577 ppt, respectively, and the 187Re/188Os ratio fluctuates between ∼97 and 845. The initial Os isotope composition of the samples (187Os/188Os(i)) is extremely variable, with values ranging from ∼0.20 to 2.81. Of the 11 samples, 8 have highly radiogenic values (1.36-2.81), and 5 of these have 187Os/188Os(i) greater than 2. These samples contain the lowest levels of Re (1.5-11 ppb). When compared with the stratigraphic column (Fig. 5-1) and considering the sampling interval, no relationship exists between 187Os/188Os(i) and lithology or stratigraphic position.   Samples from LC1 contain ∼4.5-18 ppb Re and ∼93-144 ppt Os. Values for the 187Re/188Os ratio are comparable to those at FCD, varying from ∼184 to 1217. The initial Os isotope ratios are less variable and more unradiogenic than those at FCD, and range between ∼0.11 and 0.48 (Fig. 5-2).  Sample Re and Os abundances at LC2 are lower than those at FCD and LC1, and 61  range from ∼1 to 10 ppb and from ∼35 to 90 ppt, respectively. The 187Re/188Os ratios are comparable to those measured at FCD and LC1 (∼136-815). Similarly, the 187Os/188Os(i) values at LC2 are low in comparison to those from FCD (∼0.12-0.91; Fig. 5-2). As with the samples at Five Card Draw, no trend can be drawn between the initial Os isotope composition of the samples at Last Creek, and their stratigraphic height or lithology.     Fig. 5-2 Total Organic Carbon,δ13Corg,and Re-Os isotope profiles for LC1 and LC2.  62  5.3  Discussion   5.3.1  Comparing carbon isotope profiles from Five Card Draw and Last Creek It is important to note that this study focuses on carbon isotope profiles for bulk organic matter, and does not differentiate between the marine versus non-marine components. As such, the discussion and interpretations herein focus on trends observed in the bulk carbon isotope record, and comments cannot be made on the isotopic behavior within the individual carbon isotope reservoirs.  The FCD1 section is the most complete of the four sections detailed in this study. The δ13Corg profile shows little variation from the base of the Leslei Zone, with values fluctuating continuously between a limited range of -24 to -26‰ (averaging ∼ -25.7‰). Additionally, the TOC concentration is consistently low (averaging ∼0.5 wt%) with limited variation. The FCD2 section, which corresponds to the base of the Carinatum Zone to the base of the Harbledownense Zone, exhibits comparable δ13Corg and TOC profiles, with the exception of intermittently dispersed TOC values of ∼1.0-2.8 wt% (Fig. 5-1). Such low TOC values for both sections demonstrate that the extent of organic carbon burial at Five Card Draw was minimal, and further, that water-column stagnation and water-column anoxia are unlikely to have been a factor here (cf. Jenkyns and Weedon, 2013). Some fluctuation may have been noted in the dataset if both marine and non-marine components of the bulk organic matter had been analyzed. However, the relative continuity of the bulk δ13Corg values indicates that overall the bulk organic carbon reservoir at Five Card Draw remained consistent and undisturbed during this part of the Sinemurian.  Some subtle shifts in the δ13Corg and TOC profiles are observed in the LC1 section (base of the Leslei Zone; Fig. 5-2). The δ13Corg values at LC1 average ∼-25‰ over the 20m section, and show a subtle negative shift to ∼-23‰ at approximately 14m. This is followed, stratigraphically, by an increase in TOC concentration at ∼16 m (to ∼3 wt%). Otherwise, TOC levels remain consistently low (< 1 wt%) for the duration of this section.   63  Conversely, marked shifts in δ13Corg values are exhibited at LC2 (upper part of the Leslei Zone; Fig. 5-2). Notably, a gradual positive shift in the carbon isotope profile occurs from 0-29 m in the section (from ∼-26.8 to -23.7‰); possibly driven by increased levels of primary productivity (Jenkyns and Weedon, 2013). This is punctuated by an abrupt negative carbon isotope excursion (CIE) at ∼30 m where values return to ∼-26.8‰ (Fig. 5-2). The δ13Corg profile then recovers abruptly to values of ∼-23.9‰. As discussed later, negative δ13Corg excursions observed in organic-rich marine sediments are caused by increased input of 12C into the oceanic atmospheric reservoir, and can be driven by a number of factors including: volcanogenic CO2 emissions, dissociation of gas hydrates and upwelling of 12C-enriched bottom-waters.  As in the Five Card Draw section, TOC concentrations for LC1 and LC2 are low (mostly < 2 wt%), indicating minimal levels of organic carbon burial and preservation. Again, this suggests that the depositional environment in this part of the Panthalassa Ocean was neither stagnant nor anoxic at this time.  However, the gradual positive CIE and abrupt negative CIE are restricted to the upper part of the Leslei Zone at Last Creek. There is no biochronologic or sedimentary evidence to suggest that this interval is missing at Five Card Draw. This suggests that the driving mechanisms for these isotopic shifts were either only present in this specific intra-ocean setting of Panthalassa, or that they were just not recorded in the shallower marginal setting at Five Card Draw. To investigate this further, it is critical that we understand the environments in which these sections were deposited. In addition, comparison with coeval datasets from other global locations will allow us to evaluate whether the signal at Last Creek was influenced by a widespread, potentially global causal mechanism.   5.3.2  Comparing Five Card Draw to Last Creek: restricted vs. open-ocean?  Determining the depositional Os isotope composition of marine sediments (initial Os, expressed as 187Os/188Os(i)) can yield important information regarding the ocean 64  chemistry at the time of deposition. In turn, evaluation of variations in ocean chemistry can provide the key to enhancing our understanding of the depositional environment. The Os isotope composition (187Os/188Os) of seawater can be directly controlled by three major inputs: (1) radiogenic input from weathering of continental crust (187Os/188Os of ∼1.4; Peucker-Ehrenbrink and Jahn, 2001); (2) unradiogenic contribution from meteorites (187Os/188Os of ∼0.12; Ravizza and Peucker-Ehrenbrink, 2003); (3) an unradiogenic signal from a mantle-derived source (187Os/188Os of ∼0.12; Allègrea and Lucka, 1980; Esser and Turekian, 1993; Sharma et al., 1997; Levasseur et al., 1998; Peucker-Ehrenbrink and Ravizza, 2000).     Fig. 5-3  Plot comparing the initial 187Os/188Os values for FCD1 (blue squares), LC1 (solid red squares) and LC2 (hollow red squares). The transparent blue box indicates 1 standard deviation either side of the average 187Os/188Os(i) value for FCD1 (1.6), and the red box indicates 1 standard deviation either side of the average 187Os/188Os(i) value for LC1 and LC2 (0.36). Dashed lines indicate 187Os/188Os threshold values: 1. Average mantle value (0.12); 2. Estimation of Early Jurassic steady-state seawater 187Os/188Os value (0.47) taken from (Kuroda et al. (2010); and 3. Average value of continental crust (1.4).   The present-day seawater Os isotope composition may be relatively uniform 65  (187Os/188Os ratio of ∼1.06; Levasseur et al., 1998; Peucker-Ehrenbrink and Ravizza, 2000) but it has varied significantly throughout geological time. The short seawater residence time of Os of ∼10-40 Ka (Ferguson and Muller, 1949; Sharma et al., 1997; Levasseur et al., 1998; Oxburgh, 1998; Peucker-Ehrenbrink and Ravizza, 2000), longer than the mixing time of the oceans (∼2-4 Ka; Palmer et al., 1988), allows the Os isotope composition to respond rapidly to any alterations in the composition and flux of these inputs (Oxburgh, 1998; Cohen et al., 1999). This has been successfully exploited by past studies, where Os has been used as a chemostratigraphic marker of significant volcanic events (Cohen et al., 1999; Ravizza and Peucker-Ehrenbrink, 2003).  In order to look critically at the Os data herein there needs to be an understanding of the background seawater Os isotope composition at this time. However, currently no studies conclusively document background seawater Os for the Early Jurassic. The first estimation of stable, steady-state 187Os/188Os values for the Sinemurian is given as ∼0.47 (Kuroda et al., 2010). The sampled section (Triassic-Jurassic chert succession from Kurusu, Japan; Kuroda et al., 2010) was positioned to the east of the separating supercontinent, in an intra-ocean setting. The recorded Os isotope composition would have likely been less directly affected by nearby continental flux, and potentially may be a good representation of open ocean chemistry at this time. For this investigation, we will assume that this value represents the best estimation of the background seawater Os isotope composition during the Early Jurassic.  The 187Os/188Os(i) values from Last Creek (LC1 and LC2) fluctuate steadily between ∼ 0.11-0.91 (Table 5-1; Fig. 5-2). Of the 17 samples, 9 have 187Os/188Os(i)  values of < 0.30, indicating an unradiogenic Os flux into the water column. Whilst the sampling interval is relatively low resolution, it is likely that these values result from a juvenile, mantle-derived flux rather than an extraterrestrially-derived source, based upon the shape of the Os isotope profile. Following a meteorite impact, such as that at Cretaceous-Paleogene boundary, the Os isotope profile will suddenly shift to unradiogenic 187Os/188Os values, before a gradual 66  recovery to steady-state values over ∼200 Ka (Ravizza and Peucker-Ehrenbrink, 2003). Although the extraterrestrial flux to Earth during the Jurassic is poorly constrained, there is currently no evidence external to this study that supports a meteorite impact event at this time. Rather, an open-ocean arc depositional setting with an intermittent flux of unradiogenic Os is more likely to explain the 187Os/188Os(i) values observed at Last Creek.  The Os isotope composition of samples from ∼40 m of the upper part of the Leslei Zone at Five Card Draw, ranges from ∼0.20-2.81 (Table 5-1, Fig. 5-1). However, of these samples (n=11), only 1 has an Os isotope composition that can be interpreted as unradiogenic (∼0.20). Further, and in contrast to Last Creek (Fig. 5-3), 7 have radiogenic 187Os/188Os(i) values that are greater than the average documented 187Os/188Os(i) value for continental crust (∼1.4; Peucker-Ehrenbrink and Jahn, 2001). This indicates that there was a significant contribution of continental material, likely highly evolved and rich in radiogenic Os, into the water column at Five Card Draw during this time. A number of possible sources, known to have high concentrations of Re and therefore radiogenic Os, may have eroded into the water column to produce the observed radiogenic Os isotope signal, including: (1) old and highly evolved continental crust; (2) black shales; and (3) a mineral deposit (sulphide-rich).   Five Card Draw is known to have been deposited in a continental margin setting, and so the presence of an erosional continental component in these samples should be expected. However, the presence of such highly radiogenic Os isotope values strongly indicates that, as well as the occurrence of persistent continental inundation in this area, free circulation with the open ocean at this time in the Sinemurian was not occurring. This can be further supported by comparing the Last Creek (open-ocean signal) and Five Card Draw datasets (Fig. 5-3). This study therefore suggests that deposition at Five Card Draw occurred in a partially restricted basin on the continental margin. Such a marked contrast between the depositional settings of these two field sites (Nevada and an allochthonous terrane) is also noted in a preliminary global Neodymium dataset assembled by Dera et al. 67  (2014).  Furthermore, early mapping of the Triassic rocks adjacent to the Pamlico-Luning lithotectonic assemblage showed facies distributions suggesting a partially enclosed embayment on the western margin of the continent (Ferguson and Muller, 1949). The basin named the ‘Luning Embayment’ by Ferguson and Muller (1949) was the depositional setting for the Volcano Peak Group which includes the Sunrise Formation (Taylor et al., 1983; Taylor and Smith, 1992).   5.3.3  A global carbon isotope excursion at Last Creek? To gain a global perspective on fluctuations within the carbon reservoir during the Sinemurian, it is necessary to compare coeval data from ocean basins that are: (1) geographically far-removed and (2) contain sediments from various depositional settings. As has been described, carbon-isotope data from western North America was compiled from two areas of the northeast Panthalassa that represent sedimentary deposition in an open-ocean environment (Last Creek) and in a restricted basin setting (Five Card Draw). These datasets were then compared with those previously established for the epicontinental seaway of northwest Europe (Fig. 5-4). In the European dataset, there is a large gradual ∼4‰ positive δ13C excursion throughout the Turneri Zone, where values reach ∼-24‰ in the upper part of the zone before showing a gradual return to more negative values of ∼-28‰ in the Obtusum Zone (Fig. 5-4; Jenkyns and Weedon, 2013). Jenkyns and Weedon (2013) note that this positive excursion does not co-occur with an elevated concentration of organic carbon in the upper part of the Turneri Zone and therefore cannot be attributed to local patterns of organic matter burial (such as water column deoxygenation). Rather they point to a long-term change in seawater isotope chemistry to explain the positive excursion. In support of this, van de Schootbrugge et al. (2005) and Schwab and Spangenberg (2007) also note a similar positive peak in δ13C records during the Turneri Zone in the Tethyan domain. In addition, 68  Jenkyns and Weedon (2013) highlight a prominent negative excursion at the Obtusum-Oxynotum boundary (which is equivalent to the Carinatum-Harbledownense boundary at FCD2), that they have attributed to palaeoclimatic and faunal changes (Fig. 5-4).     Fig. 5-4  Figure comparing δ13Corg data from western North America (Five Card Draw and Last Creek; this study) with a coeval δ13Corg dataset from Europe (Dorset, UK; Jenkyns and Weedon, 2013). Yellow box marks positive CIE observed in western North America and UK. Orange box shows negative CIE observed at Last Creek (blue line). Green, red and blue lines denote FCD1, FCD2 and LC1 & 2 sections, respectively. Biostratigraphy is given to demonstrate correlation of Sinemurian zonation in North America and Europe.   In western North America, a pronounced positive excursion of similar magnitude 69  and duration is recognized at the Last Creek locality (blue line in Fig. 5-4). As with the European data, this positive carbon-isotope excursion from the un-restricted northeast Panthalassa does not co-occur with elevated organic carbon burial (Fig. 5-2). However, our data differs in that there is a large (and abrupt) negative shift of ∼3‰ in the uppermost Leslei Zone which seems to interrupt the pronounced gradual positive excursion. During this abrupt negative CIE, values reach ∼-27‰ for ∼4m in the section. Curiously, as previously discussed, this pattern is not evident in the coeval succession at Five Card Draw (green and red lines in Fig. 5-4). Throughout the upper part of the Leslei Zone, carbon-isotope values predominantly range between -25‰ and -26‰ and do not show any positive or negative trend. Similarly there is also no indication of elevated organic carbon burial throughout this interval. Further, δ13Corg values at Five Card Draw 2 show a subtle positive increase (∼1‰) throughout the duration of Carinatum Zone, in contrast to the abrupt negative excursion seen in Europe at the Obtusum-Oxynotum interval (Jenkyns and Weedon, 2013).  The distinct similarities between the positive CIE in the upper part of the Leslei Zone (approximately equivalent to the Turneri Zone) observed in the Last Creek and Dorset sections, suggest that these sites likely record a widespread and potentially global carbon isotope signal. The lack of comparable signals at Five Card Draw indicates, however, that this signal may only have been recorded in open-ocean or unrestricted marine environments, and in turn, that basinal restriction may hide global carbon cycle records. As with the conclusions of Jenkyns and Weedon (2013), the event in western North America is not correlative with significant organic carbon enrichment and therefore was not controlled by local basin stagnation and water column deoxygenation. Rather, a more likely explanation might involve increased and widespread primary productivity that may be associated with eustatic sea level rise (noted in Donovan et al., 1979; Jenkyns and Weedon, 2013). Further, heightened inundation of continental material into the basin at Five Card Draw may have played a key role in suppressing a carbon isotope signal induced by such increased levels 70  of primary productivity.  The positive CIE interval in Panthalassa is interrupted by an abrupt negative CIE that only seems to occur in the Last Creek section. In the geological record, negative CIEs are thought to record the injection of isotopically light carbon (12C) into the oceanic- atmospheric reservoirs by a number of sources that include: up-welling of 12C-rich bottom water (ocean reservoir only) (Küspert, 1982; Jenkyns, 1988; McArthur et al., 2008), dissociation of gas hydrates ( δ13C=∼-60‰, Hesselbo et al., 2000), volcanogenic CO2 emissions (δ13CCO2 between −5‰ and −25‰, Deines, 2002) and oxidation of organic matter on exposed shelf sediments during eustatic sea level fall (Jenkyns et al., 2002 and references therein). In relation to these potential sources, the abrupt negative CIE in the upper part of the Leslei Zone: (1) does not occur in multiple localities, implying that it is being driven locally; (2) does not contain δ13C values that are indicative of methane gas release (e.g., >-30‰ in Hesselbo et al., 2000), assuming that any methane added to the reservoir would be present in recognizable amounts; and (3) occurs during a time of eustatic sea level rise and therefore could not be caused by the oxidation of organic matter during regressive cycles. This study therefore suggests that the negative CIE observed only at Last Creek may have been driven by localized bottom-water upwelling during the sea-level rise.   5.4  Conclusion   Investigation of two field sites from western North America has yielded a number of important conclusions regarding Sinemurian depositional environments and ocean chemistry: (1) Although bulk TOC profiles for Five Card Draw (Nevada) and Last Creek (British Columbia) are comparable, bulk carbon isotope profiles at Last Creek show significant variation, in contrast to those at Five Card Draw.  (2) Osmium isotope analysis demonstrates that the successions at Five Card Draw 71  and Last Creek were deposited in contrasting environments (partially restricted vs. open-ocean).  (3) The gradual positive CIE observed at LC2 corresponds to a coeval positive CIE of similar duration in Dorset, UK (Jenkyns and Weedon, 2013), and additional Tethyan domains (van de Schootbrugge et al., 2005; Schwab and Spangenberg, 2007) suggesting that this is a globally controlled CIE. A likely causal factor may have been a widespread increase in primary productivity.  (4) Although present on a potentially global scale, this positive CIE is not observed at Five Card Draw. Deposition in a partially restricted basin, combined with significant continental inundation, is likely to be the reason for this.  (5) An abrupt negative CIE is observed at LC2 but is not present at Five Card Draw nor in the European section, suggesting that this CIE was driven by mechanisms local to this specific field site. The most likely cause is upwelling of 12C-rich bottom-waters.    72  CHAPTER 6       SYSTEMATIC PALEONTOLOGY  6.1  Introduction  The ammonoid specimens dealt with in this chapter are mostly from collections in this work, but are also supplemented by previous GSC collections from Taseko Lakes and the collection from Nevada of Dr. Paul Smith’s PhD study (Smith, 1981). This taxonomic work is intended to provide the raw data for biostratigraphic, biogeographic and chemostratigraphic analysis, and also to serve as a major part of the systematics of the North American Sinemurian Zonation.  The classification of the ammonoids in this work involves with two superfamilies: Lytoceratoidea and Psiloceratoidea. The systematics of Lytoceratoidea largely follows Hoffmann (2010), who reviewed and revised the whole superfamily, whereas the systematics of Psiloceratoidea mostly follows the updated edition of the Treatise on Invertebrate Paleontology (Howarth, 2013). The earlier outline given by Donovan et al. (1981) and the opinions of some other major recent work (e.g., Dommergues, 1993; Hillebrandt, 2002; Rakús and Guex, 2002; Dommergues et al., 2008; Guex et al., 2008; Meister and Schlögl, 2013) are also referred to wherever there are deviations.  The studied interval and the specimens described herein is a subset of the whole Sinemurian, and may not reflect the overall diversity of the ammonoid fauna of the Western Cordillera. However, this could be supplemented by incorporating some major previous work (e.g., Frebold, 1967; Imlay, 1981; Smith, 1981; Pálfy, 1991; Taylor, 1998; Macchioni et al., 2006).  The abbreviations and format of the open nomenclature and synonymy list follows the suggestions of Matthews (1973) and Bengtson (1988) in cases of limited preservation and provisional identification.  73   6.2  Measurements and Abbreviations  The measurements, standard abbreviations and the descriptive terms of the ammonoid morphology are adopted from Smith (1986). All measurements are millimeters. The abbreviations of measured parameters and symbols are listed as follows:   D = shell diameter UD = umbilical diameter U = UD/D, umbilical ratio WW = whorl width WH = whorl height WWWH = WW/WH, whorl shape PRHW = primary ribs per half whorl, or rib frequency EXP = whorl expansion rate * = the holotype in the synonymy list ~ = approximate  The approximate values of the measurements are provided when preservation is limited. Plots of rib frequency (PRHW), whorl height (WH), and whorl expansion rate (EXP) against umbilical diameter (UD) are often used to show morphological changes throughout ontogeny. The suture lines are used to aid the identification whenever available, followed the terms defined in Arkell et al. (1957). The images and measurements of AMMON database (Liang, 1994; Liang and Smith, 1997) are also used to aid the systematic description. For the Arietitidae, the concepts of the semi-quantitative approach proposed by Corna and Dommergues (Corna and Dommergues, 1995), modified by Meister and Schlögl (2013) are referred to but not fully adopted in this work.  74  6.3  Systematic descriptions  Class CEPHALOPODA Cuvier, 1798 Subclass AMMONOIDEA Zittel, 1884 Order AMMONITIDA Fischer, 1882 Suborder LYTOCERATINA Hyatt, 1889 Superfamily LYTOCERATOIDEA Neumayr, 1875 Family PLEUROACANTHITIDAE Hyatt, 1900 Subfamily FUCINITINAE Venturi & Ferri, 2001 Genus FUCINITES Gugenberger, 1936.  Type species: Fucinites sicilianus GUGENBERGER, 1936a; subsequent designation by ARKELL et al. (1957).    Description:  The shell size ranges from fairly small to large. Evolute form. Whorl section subrectangular to subquadrate. Flanks flat, umbilical shoulders rounded. The fine ribs are straight, dense (PRHW>40), and gently prorsiradiate. Median keel rather distinct throughout ontogeny. The nucleus can be smooth, or tuberculated (Meister et al., 2011) up to 10 mm.   Remarks:  The genus Fucinites is similar to Lytotropites, but differs from it by the presence of a median keel throughout ontogeny, more compressed whorl section, and no change in the 75  ribbing pattern with growth. Fucinites used to be classified under the Family Ectocentritidae SPATH, 1926 (Arkell et al., 1957; Wiedmann, 1970). Rakús (1999) classified this genus under the Subfamily Ectocentritinae, within the Family Analytoceratidae SPATH, 1927 but stated that Fucinites, together with Lytotropites may belong to the Family Pleuroacanthitidae HYATT, 1900, based on the early tubercular stage (Knötchen), which is not present in the type specimen nor in this work. Venturi and Ferri (2001) established a Subfamily Fucinitinae to include Fucinites, due to its morphological differences with Ectocentrites. This classification was adopted and emended by Meister et al. (2011). Despite all these opinions, it is generally agreed that Fucinites should be placed within the Superfamily Lytoceratoidea NEUMAYR, 1875 except Hoffmann (2010), who argued that it should be excluded from Lytoceratoidea based on the presence of a keel, the absence of the tubercular stage in other lytoceratid genera and the unknown internal suture line; he did not propose a new classification. This work is in favor of the classification of Meister et al. (2011) but it is suggested not to overemphasize the importance of the early tubercular stage (Knötchenstadium) since it’s not a character in all Fucinitinae, and the revision of the definition of the genus Fucinites is provided herein.   Age and distribution:  Fucinites is known from the Lower Sinemurian of Sicily (Gugenberger, 1936a) and Monte Cetona (Bucklandi Subzone; Venturi and Nannarone, 2002) in Italy; western Carpathians in Slovakia (Meister et al., 2011); and from Last Creek, British Columbia (probably Involutum Zone).    Fucinites sicilianus GUGENBERGER, 1936 Page 173, Plate 1, Fig. 1.  76  * 1936a Fucinites sicilianus n. gen. n. sp.  GUGENBERGER, p. 175, pl. 15, fig. 1a-d.  2001 Fucinites sp. indet VENTURI & FERRI, p. 80. cf. 2002 Fucinites sicilianus GUGENBERGER – VENTURI & NANNARONE, p. 143, pl. 4, fig. 3.  2011 Fucinites sicilianus GUGENBERGER – MEISTER et al., p. 44, text-fig. 13; p. 45, fig. 14.a-b; p. 46, fig. 15.a-d.  Material: 1 complete glacial float from Last Creek preserved in shale.   Measurements:  Specimen # D UD U WW WH WWWH PRHW EXP T 02 220.0 104.0 0.47 68.0 66.5 1.02 49 1.71  Description:  This specimen is a very large (D>200 mm), evolute form. The body chamber is not preserved, so the actual size could be larger. The whorl section is weakly compressed and subrectangular when D<200 mm, and gradually becomes very weakly depressed and subquadrate at larger shell diameters. Flank is slightly convex in inner whorls but becomes fairly flat in outer whorl. Umbilical wall is high and vertical throughout ontogeny except the nucleus, which is inclined. The ventro-lateral shoulder is wide and rounded. The venter is wide and convex. There is a fairly prominent median keel on the venter, shouldered, no sulcus. Keel strength persists throughout ontogeny. The nucleus is smooth up to 10mm, then followed by dense ribbing (PHRW>40). The ribs are straight, gently prorsiradiate. They start from the umbilical seam, reach the median keel where there is a slight decrease in the rib strength, and then pass over the venter and regain the former strength. Only the first saddle and lobe of the suture line is preserved, bifid, not deeply incised.    77  Discussion:  This specimen resembles Fucinites sicilianus GUGENBERGER, which is the only comparable species in the genus, and therefore is placed within it. There is plenty of room for discussion since the classification of the genus is still in debate. This specimen agrees with the type specimen at comparable shell size. This species differs from Fucinites gemmellaroi GUGENBERGER by being more densely ribbed and having a keel throughout ontogeny. Meister et al. (2011) recorded the same species from Slovakia, but their specimens differ from this one by having tuberculated nuclei. One of their specimens has much lower rib frequency (p.46, fig. 15a-b in Meister et al., 2011) at comparable shell size, and the ribs project forward onto the venter markedly, which is not seen on any other specimens. The difference with Tipperoceras mullerense TAYLOR is discussed under Tipperoceras.   Occurrence and Distribution:   This specimen was collected ex situ from the headwaters of Last Creek, probably Involutum Zone. Distribution same as for genus.   Locality: T 02.   78  Family ECTOCENTRITIDAE Spath, 1926 Genus ECTOCENTRITES Canavari, 1888  Synonymy: Bartoliniceras TAYLOR, GUEX & RAKÚS, 2001.   Type species: Ammonites petersi HAUER, 1856, p. 65, pl. 21, figs. 1-3. Subsequent designation by Bonarelli (1899).   Description:  Small to large evolute forms with subrectangular to oval whorl section. Whorl expansion rate moderate. Venter is typically smooth. Ribs are often dense, straight or slightly flexuous of fine to medium strength, sometimes restricted within the upper flank.   Age and Distribution: Ectocentrites ranges from the Upper Hettangian to the Upper Sinemurian (Hoffmann, 2010), and possibly to the Lower Pliensbachian (Meister et al., 2000). It’s a cosmopolitan taxon and has been reported from the following areas:   Europe: Austria (Böhm et al., 1999); Italy (Bonarelli, 1899); Hungary (Géczy and Meister, 2007); Slovakia (Meister et al., 2011); Romania (Tomas and Pálfy, 2007). North America: Yukon and Northwest Territories (Poulton, 1991), British Columbia (Pálfy, 1991); Nevada ; Mexico (Blau et al., 2008; Meister et al., 2009). Elsewhere: Viet Nam (Meister et al., 2000); New Zealand (Stevens, 2012).    Ectocentrites leslei (TAYLOR, GUEX & RAKÚS 2001) Page 175, Plate 2, Fig. 1-4.  79   1956 Geyeria cf. serorugata GEYER – ERBEN, p. 170, pl. 27, figs. 7-10.  1991 Tragolytoceras ? sp. PÁLFY, p. 78, pl. 2, fig. 2. * 2001 Bartoliniceras leslei. TAYLOR, GUEX & RAKÚS, p. 402, pl. 3, figs. 1-3.  2002 Ectocentrites leslei (TAYLOR, GUEX & RAKÚS) – MEISTER et al., pl. 1, figs. 14, 15.  Materials: 12 specimens from Five Card Draw preserved in shale and limestone 1 specimen from Paradise Creek, Taseko Lakes preserved in calcareous siltstone.   Measurements:  Specimen # D UD U WW WH WWWH PRHW F1-30-05 20.4 9.0 0.44  6.7  14 F1-21-07-4 23.5 10.6 0.45  7.8  ~16 F1-21-03-1 23.7 8.4 0.35  8.8  ~16 F1-21-08-1 25.0 10.4 0.42  8.5  ~17 T 12 ~19.0 ~7.9 0.42 5.6 5.7 0.98 ~19  Description:  Small, evolute forms with smooth nucleus. Ribbing begins at diameter of 6~9 mm. Ribs are strong and prorsiradiate. They only appear on the upper half of the flank, curve forward onto the venter to form an obtuse chevron pattern. Rib strength is greatest at ventro-lateral shoulder. Umbilical wall is fairly low. Flanks are flat. The whorl section is compressed, and the venter is elliptic but slightly fastigate, with a very blunt and obscure keel. The umbilical ratio, whorl height and rib frequency gradually increase with growth (Fig. 6-1).   Discussion:  Taylor et al. (2001) erected a new genus Bartoliniceras, based on one species B. 80  leslei which was subsequently assigned to Ectocentrites by Meister et al. (2002). Thus, the genus Bartoliniceras is abandoned.  The ribbing pattern of this species is unique in the Sinemurian, which makes it distinct even in flattened specimens or fragments. The species Tragolytoceras ? sp. in Pálfy (1991) has all the same characters except that the ventral view is not available due to preservation, and therefore is synonymized herein. Blau et al. (2008) reported a similar but stratigraphically higher species, Ectocentrites hillebrandti, the juvenile form of which has a similar upper-flank ribbing pattern, but it changes to full-length ribbing when the shell size reaches 20~25 mm, and can grow to much larger sizes. It also has a slightly bigger smooth stage than E. leslei.   Occurrence and Distribution:  This species occurs from the lower part of the Leslei Zone to the lower part of the Carinatum Zone in both Nevada and British Columbia. The specimen T 12 was collected from Paradise Creek in Taseko Lakes map area, in association with Arnioceras miserabile.  Ectocentrites leslei is endemic to North America. It has been found in British Columbia (Pálfy, 1991); Nevada (Taylor et al., 2001) and Sierra Madre Oriental, Mexico (Meister et al., 2002).   Localities: F1-11, F1-21, F1-30; T 12.    81     Fig. 6-1 Shell size (D), whorl height (WH), and rib frequency (PRHW) plots of Ectocentrites leslei, compared with that of Meister et al. (2002), Taylor et al. (2001) and Pálfy (1991).  10.018.026.034.042.05.0 7.5 10.0 12.5 15.0 17.5DMeister et al.,2002Taylor et al.,2001Pálfy,1991FCDLC2.05.08.011.014.05.0 7.5 10.0 12.5 15.0 17.5WH8121620245.0 7.5 10.0 12.5 15.0 17.5PRHWUD82  Family LYTOCERATIDAE Neumayr, 1875 Subfamily LYTOCERATINAE Neumayr, 1875 Genus LYTOCERAS Suess, 1865  Type species: Ammonites fimbriatus SOWERBY, 1817, by original designation.   Synonymy: see Wiedmann (1970), and Hoffmann (2010).  Description:  Shell size varies from small to very large, moderately evolute to fairly evolute. Whorl section subcircular or subquadrate, compressed or depressed. Whorl expansion rate around 2. Flanks, venter, umbilical wall, ventrolateral shoulder are all rounded. No keel or sulci. Shell ornamentations include densely ribbing, growth lines, flares or constrictions. Sutures highly subdivided, typical formula E L U2 U1 IS (Hoffmann, 2010).   Remark:  Lytoceras is a genus regarded to be highly variable in morphology and connected by many transitional forms between the extreme forms. The typical suture line and the ontogenetic change of the lateral lobe from trifid to bifid is identical. Some detailed treatments are given by Wiedmann (1970) and Hoffmann (2010).   Age and distribution:  Lytoceras is a long-ranging genus from Lower Jurassic (Lower Sinemurian) to Upper Cretaceous (Cenomanian). It has a worldwide distribution including the following areas:  Europe and Northern Africa: UK (e.g., Sowerby, 1817); Switzerland (e.g., 83  Dommergues et al., 2012); Austria (Blau, 1998); Italy (e.g., Gugenberger, 1936a, 1936b); Romania (e.g., Tibuleac, 2005); Slovakia (Meister et al., 2011) Morocco (e.g., El-Harriri et al., 2010); Algeria (e.g., Dommergues et al., 2008); Tunisia (e.g., Rakús and Guex, 2002). North America: Alaska (Imlay, 1981); ?Yukon (Poulton, 1991); British Columbia (e.g., Pálfy, 1991). South America: Argentina (e.g., Spalletti et al., 2012). Asia: India (e.g., Krishna et al., 2000), Turkey (e.g., Alkaya and Meister, 1995).    Lytoceras sp. Page 175, Plate 2, Fig. 5.  Materials: 1 specimen from Last Creek well preserved in calcareous sandstone.   Measurements:  Specimen # D UD U WW WH WWWH EXP T 14 16.8 7.7 0.46 5.5 4.6 1.2 1.97  Description:  This specimen is a small, moderately evolute form. Whorl section subcirular and depressed. The flanks, venter and ventrolateral shoulder are all convex and rounded. The venter is smooth, no keel or sulcate, except that there appears to be a very blunt keel near the opening of the shell. The shell is completely smooth throughout, except for some fine constrictions. The whorl section becomes more depressed near the opening, and the whorl sides flare outwards, indicating the aperture. Suture line is highly subdivided, typical for lytoceratid, with relatively high lateral lobes, and broad, probably trifid lateral saddles (Fig. 6-2).    84  Discussion:  This specimen resembles Lytoceras by its constrictions, whorl expansion rate and identical suture line. It’s a small adult that can be potentially the microconch of some larger species. It can be compared tentatively to Lytoceras aff. celticum illustrated by (Guex et al., 2008, pl. 2, fig 2), but their specimen has fine convex ribbing and the whorl section seems more compressed. Pálfy (1991) recorded several poorly preserved specimens of Lytoceras from the base of Sinemurian, which are much larger in size and older in stratigraphic age. Bourillot et al. (2008) illustrated a similar small and smooth species, named Alocolytoceras dorcadis, but it clearly has flares in a later growth stage and is from Toarcian. The only local similar form is Eolytoceras tasekoi erected by Frebold (1967), but it is finely ribbed, and much larger in size and from Hettangian. This is the first report of Lytoceras in Last Creek in Taseko Lakes, and may have provide some insight about the diversity of the ammonite fauna in this area.   Occurrence and Distribution:  This specimen was collected from the headwaters of Last Creek in association with Arnioceras.   Localities: T 14.    Fig. 6-2 Septal suture of Lytoceras sp. at WH=4.8 mm. Specimen T 14.  85  Suborder AMMONITINA Fischer, 1882 Superfamily PSILOCERATOIDEA Hyatt, 1867 Family ARIETITIDAE Hyatt, 1875 Subfamily ALSATITINAE Spath, 1924 Genus TIPPEROCERAS Taylor, 1998  Type species: Tipperoceras mullerense TAYLOR, 1998, by original designation.   Description:  Characterized by its evolute, compressed inner whorls with dense, straight or slightly curved ribs, and keeled-acute venter. The outer whorls become stout with fewer but stronger ribs at large sizes (over 150 mm), and lower, blunter keel.   Remarks:  This genus was derived from Pseudaetomoceras in Hettangian (Taylor, 1998; Howarth, 2013). Specimens in this work show clear distinctions between Tipperoceras and Fucinites (discussed under Tipperoceras mullerense), which doesn’t support the suggestion by Meister et al. (2011) to synonymize the two genera.   Age and Distribution:  Tipperoceras is currently known from the Involutum Zone of British Columbia, Nevada (Taylor, 1998; Taylor et al., 2001), and possibly New Zealand (Stevens, 2004).    Tipperoceras mullerense TAYLOR, 1998 Page 175, Plate 2. Figs. 6-8; Page 177, Plate 3, Fig. 1. 86   * 1998 Tipperoceras mullerense TAYLOR, p. 495, figs. 23.3-23.6.  Materials: 3 specimens from the Five Card Draw preserved in limestone, and 3 specimens from Last Creek preserved in calcareous concretions in shale.    Measurements: Specimen # D UD U WW WH WWWH PRHW T 05    42.2 49.0 0.86 ~25 F3-11 23.9 11.4 0.48 5.9 5.7 1.04 ~25 F3-12 22.6 10.1 0.45 5.6 5.8 0.97 ~24 F3-13 35.6 16.8 0.47 9.6 9.9 0.97 31 T 04    61.5 65.5 0.94  T 01  143.0  72.8 67.0 1.09 ~14  Description:  Size varies from a few centimeters to over 200 mm. Evolute forms. Umbilicus is slightly less than 50% of diameter. The umbilical wall is low but becomes higher with growth. Ribs are straight, dense, and rectiradiate. Rib strength increases with growth. Flanks are flat to slightly convex. The venter is rather inflated, and the whorl section is ogival to subtriangular. The keel is sharp at small shell sizes, around 1~2 mm in height, no sulcus or lateral keel. There are distinct ontogenetic changes. The rib density first increases with ontogeny then decreases at large sizes. The rib strength increases steadily with growth. At sizes over 120 mm, the ribs become swollen towards the venter and sometimes weakly tuberculated. The keel gradually becomes stout and blunt. The whorl section changes from compressed to slightly depressed at shell diameters over 100 mm (Fig. 6-3).   Discussion:  The specimens resembles the type specimen in Taylor (1998), except being slightly 87  lower in rib density, which could result from variation within the species. This species differs from the Fucinites sicilanus established by Meister et al. (2011) by the absence of tubercles on the first few whorls, no forward projection of the ribs onto the venter, and by the more compressed inner whorls and more depressed outer whorls. The unfigured material ?Tipperoceras sp. indet. from New Zealand is poorly preserved and only tentatively compared to Tipperoceras mullerense by Stevens (2004).     Fig. 6-3 Tipperoceras mullerense TAYLOR, whorl sections with growth. Specimen numbers: a. F3-11; b. T 05; c. T 04; d. T 01.   Occurrence and Distribution:  This species occurs at the upper part of the Involutum Zone, which is equivalent to Bucklandi Subzone and Lyra Subzone in Northwest Europe. In Five Card Draw, Nevada, it was collected from the upper part of the Ferguson Hill Member, Sunrise Formation. At Last Creek, British Columbia, it was collected from the Little Paradise Member, Last Creek Formation. Tipperoceras mullerense has been recorded from Nevada (Taylor, 1998; Taylor et al., 2001) and British Columbia. Possibly also from New Zealand (Stevens, 2004).   Localities: F3-01, F3-02, F3-03, T 05, T 04, T 01.    Tipperoceras n. sp. A 88  Page, 175, Plate 2, Fig. 9.  Material: one ex situ specimen from Last Creek preserved in calcareous concretions in shale.  Measurements:  Specimen # D UD U WW WH WWWH PRHW T 07 51.0 18.4 0.36 13.6 21.1 0.64 28  Description:  Small sized, probably a juvenile form. Midvolute.  Umbilical wall low. Ribs are dense, slightly flexuous, and gently swing forward on the upper half of the flank. The ribs start from umbilical edge until the ventral keel. The flanks is slight convex. The venter is keeled without sulcus. The whorls are strongly compressed. Whorl section lanceolate, acute.   Discussion:  This species differs from Tipperoceras mullerense by being less evolute, being more compressed in whorl section, and by its flexuous ribs a higher rib density. It shows greater similarity to the Hettangian genus Pseudaetomoceras than to Tipperoceras mullerense, and might suggest a transitional form in the evolution of the two genera.   Occurrence and Distribution:  This species occurs from the upper part of the Involutum Zone, above Coroniceras and below Arnioceras miserabile. It was collected from the Little Paradise Member of the Last Creek Formation. It is currently known from British Columbia.   Locality: T 07.  89  Subfamily ARIETITINAE Hyatt, 1875 Genus TMAEGOCERAS Hyatt, 1889  Type species: Ammonites latesulcatus Hauer, 1856.  Description:  Small to medium sized. The shell is evolute to involute, mostly with no ornamentation or with very weak striae, except one species which has folds (Tmaegoceras paronai). The whorl section is rounded or nearly rectangular, weakly depressed to strongly depressed. The venter is rounded and convex, and possesses a wide and deep furrow, which is sometimes divided by a median keel. The edges of the ventral furrow sometimes become the lateral keels, higher than the median keel. The suture line is slightly denticulate (Arkell et al., 1957; Schlegelmilch, 1976; Howarth, 2013).  Remark:  This genus used to be classified under the subfamily of Alsatitinae by Arkell et al. (1957), but it was reassigned to the subfamily of Arietitinae (Crick, 1902; Donovan et al., 1981; Böhm et al., 1999; Howarth, 2013).   Age and Distribution:  Tmaegoceras occurs at the Involutum Zone in North America, equivalent to the Bucklandi Zone to the lower part of Semicostatum Zone in northwest Europe (Arkell et al., 1957; Géczy and Meister, 2007; Howarth, 2013). Up to now, it is known from:  Europe: France (Guérin-Franiatte, 1994); Germany (Gebhard and Schlatter, 1977); Hungary (Géczy and Meister, 2007); Austria (Hauer, 1856; Böhm et al., 1999); Italy (Bonarelli, 1899); Spain (Braga et al., 1984). North America: Nevada (Taylor, 1998); British Columbia. Elsewhere: New Zealand (Stevens, 2004).  90    Tmaegoceras nudaries TAYLOR, 1998 Page 175, Plate 2, Figs. 10-11.   * 1998 Tmaegoceras nudaries TAYLOR, p. 495, figs. 23.7, 23.8. ? 2004 Tmaegoceras sp. indet. STEVENS, p. 42.  Material: 1 complete specimen and 1 fragment from Five Card Draw preserved in limestone.   Measurements:  Specimen # D UD U WW WH WWWH F3-09 62.8 36.1 0.57 17.8 13.8 1.29 F3-10    21 20.9 1.00  Description:  Medium sized, smooth evolute form. The whorl section is weakly depressed, nearly square (Fig. 6-4). The WWWH ratios show a slight decrease in the degree of depression with ontogeny. Flanks are rather flat to slightly convex. Umbilical wall is low. There is a single deep furrow on the venter, the breadth of which covers a third to a quarter of the whorl width. No keel or ribbing are present. There are noticeable changes in ontogeny. In juvenile specimens with shell diameters less than 15 mm, a keel is present in the middle of the furrow, but gradually fades and disappears by 20-25 mm (Taylor, 1998).   91    Fig. 6-4 Whorl section of Tmaegoceras nudaries. Specimen F3-10.  Discussion:  This species can be distinguished from all other species of Tmaegoceras of comparable or larger sizes by the presence of a deep furrow with no keel on the venter. It can be distinguished from Tmaegoceras dorsosulcatus QUENSTEDT at small shell diameters, which doesn’t possess a keel until at larger sizes (Gebhard and Schlatter, 1977). Tmaegoceras obesus n. sp. also has a deep, non-keeled furrow on the venter, but its whorls are strongly depressed.     Occurrence and Distribution:  This species occurs at the uppermost part of the Involutum Zone (Taylor et al., 2001), equivalent to the lower part of the Semicostatum Zone in northwest Europe. The specimens were collected from the upper part of Ferguson Hill Member, Sunrise Formation. This species is currently known from Nevada.    Localities: F3-09, F3-10.     Tmaegoceras crassiceps POMPECKJ, 1901 Page 179, Plate 4, Figs. 1-2.  * 1901 Tmaegoceras crassiceps POMPECKJ, p.163, fig. 1. 92   1976 Tmaegoceras crassiceps POMPECKJ – SCHLEGELMILCH, pl. 10, fig. 6.  1976 Tmaegoceras crassiceps POMPECKJ – FÜLÖP, pl.16, fig. 1.  1977 Tmaegoceras crassiceps POMPECKJ – GEBHARD & SCHLATTER, pl.1, figs. 1 (refigured holotype), 2, 3.  1984 Tmaegoceras crassiceps POMPECKJ – BRAGA, MARTIN-ALGARA & RIVAS, pl.1, fig. 12. cf. 2007 Tmaegoceras gr. crassiceps POMPECKJ – GÉCZY & MEISTER, p. 168, pl.13, figs. 3, 5, 10.  Materials: 2 specimens from Last Creek preserved in calcareous siltstone, 1 external mold from Five Card Draw preserved in bioclastic limestone.    Measurements:  Specimen # D UD U WW WH WWWH T 03-02 26.0 10.4 0.40 14.4 9.2 1.57 T 09    30.5 21.5 1.42  Description:  Small to medium sized, evolute forms. Whorl section strongly depressed throughout ontogeny. Flanks strongly convex. Umbilical wall convex and steep, becomes lower with the increase in shell size. Venter is rounded, convex, and bisulcate-tricarinate. The height of the lateral keels and the median keel are the same at small sizes (<30 mm). The ventral furrow, about one third of the whorl width, becomes deeper and the median keel becomes much lower than lateral keels with ontogeny. No ribs or other ornamentation.   Discussion:  This species differs from T. paronai (Bonarelli, 1899) by the absence of folds on the upper flank and ventrolateral shoulder, less depressed whorls section and deeper ventral 93  grooves. It differs from T. lacordarei by being more depressed in the whorl section and having a lower whorl expansion rate. The difference with T. obesus n. sp is discussed under T. obesus n. sp.  Occurrence and Distribution:  Tmaegoceras crassiceps occurs in the middle to upper part of the Involutum Zone in North America (Taylor et al., 2001), which is equivalent to the Bucklandi Subzone to Lyra Subzone in northwest Europe. In a recent report, Tmaegoceras gr. crassiceps is found in the Rotiforme Subzone (Géczy and Meister, 2007). Two of the specimens were collected from the headwaters of Last Creek, and the other one from the Five Card Draw, Involutum Zone.  Tmaegoceras crassiceps is a cosmopolitan taxon. It has been found in southwestern Germany (Pompeckj, 1901; Gebhard and Schlatter, 1977), southern Spain (Braga et al., 1984), Hungary (Géczy and Meister, 2007) in Europe; and Nevada (Taylor, 1998; Taylor et al., 2001), British Columbia in western North America.   Localities: T 03, T 09.    Tmaegoceras cf. latesulcatum (HAUER, 1856) Page 179, Plate 4, Fig. 3.  *cf. 1856 Ammonites latesulcatus HAUER, pl. 9, figs. 1-3. cf. 1889 Tmaegoceras latesulcatum HYATT, p. 125. cf. 1901 Tmaegoceras latesulcatum HAUER – POMPECKJ, p. 165. cf. 1902 Tmaegoceras latesulcatum HAUER – CRICK, p. 127. cf. 1977 Tmaegoceras latesulcatum HAUER – GEBHHARD & SCHLATTER, p. 3-4. 94  cf. 1999 Tmaegoceras latesulcatum HAUER – BÖHM et al., p. 192, text-fig. 44; pl. 28, fig. 3.  Material: 1 fragment from Last Creek preserved in 3 dimensions in calcareous shale.   Measurements:  Specimen # D UD U WW WH WWWH T 06    26.5 ~24.5 1.08  Description:  Medium sized, evolute form. The whorl section is rounded and weakly depressed. Flank is slightly convex. No ribs or any other ornamentation. Venter is rounded and convex, bisulcate-tricarinate. The ventral furrow is deep and broad, approximately one third of the whorl width. There is a median keel in the middle of the furrow, rather sharp and prominent for this genus at comparable sizes, only slightly lower than lateral keels.  Discussion:  As far as the preservation allows, this specimen is closest to Tmaegoceras latesulcatum HAUER, but differs from it by being slightly more depressed in whorl shape. It can be readily distinguished from all strongly depressed forms in the same genus (T. crassiceps, T. lacodarei, T. paronai, T. obesus n. sp.) by the contrast in whorl shapes. The difference with T. nudaries is discussed under T. nudaries.   Occurrence and Distribution:  This specimen was collected from the upper part of the Involutum Zone from Last Creek. Tmaegoceras latesulcatum has be reported from Austria (Hauer, 1856; Böhm et al., 1999) and British Columbia.   95  Locality: T 06.    Tmaegoceras obesus n. sp. Page 179, Plate 4, Fig. 4.  Etymology: obsesus, Latin for obese. Named after morphology. .   Holotype: F3-08, Plate 4, Fig. 5, Sunrise Formation, Five Card Draw, Nevada. Monotype.  Diagnosis: ventral furrow wide and deep, no keel; whorls strongly depressed.   Material: 1 internal mold from Five Card Draw well preserved in limestone.    Measurements:  Specimen # D UD U WW WH WWWH F3-08 102.3 54.5 0.53 41.0 25.5 1.61  Description:  Medium sized and moderately evolute form with relatively large umbilicus. The umbilical wall is high and rounded, and umbilical shoulder very steep. The whorl section is strongly depressed (Fig. 6-5). Flanks and venter are strongly convex. The venter is sulcate, with no median or lateral keel. The ventral furrow is wide and deep, covering about a quarter of venter. Ventrolateral shoulder is wide and rounded. Smooth throughout ontogeny.  96    Fig. 6-5 Whorl section of Tmaegoceras obesus n. sp. Specimen F3-08.   Discussion:  This species can be distinguished from all other depressed species of Tmaegoceras (T. crassiceps, T. lacodarei, T. paronai) at comparable sizes by its higher umbilical ratio, lower whorl expansion rate, and non-keeled furrow. Currently only this species and T. nudaries have non-keeled ventral furrows among all species in Tmaegoceras. The difference with T. nudaries is discussed under T. nudaries.    Occurrence and Distribution: This specimen was collected in situ from the upper part of the Involutum Zone in Five Card Draw. Currently this species is only known from Nevada.   Locality: F3-08.  97  Genus CORONICERAS Hyatt, 1867  Type species: Ammonites kridion ZIETEN, 1830; subsequent designation by BONARELLI, 1899.     Synonymy: Pararnioceras SPATH, 1922a; Epammonites SPATH, 1922b; Arnioceratoides SPATH, 1922b; Primarietites BUCKMAN, 1926; Saccaiceras VENTURI & NANNARONE, 2002.   Description:  Size medium to large. Evolute forms with wide umbilicus. Ribs strong, rursiradiate or rectiradiate, usually bend forward at the ventrolateral shoulder. Rib frequency increases with size, but may decrease on the outer 1~2 whorls. Tubercles commonly appear at the ventrolateral end of ribs, but may fade on outer whorls. Flanks flat or slightly convex. Venter flat or convex, bisulcate-tricarinate. Keels strong but not sharp. Whorl section sub-qudrate to sub-rectangular, but may become sub-trigonal at large sizes in some species.   Remarks:  The genus Coroniceras in this work is used in a wide sense following Donovan et al. (1981) and the recently updated version of the Treatise (Howarth, 2013). However, the systematics and phylogeny remain unstable and discussions are on-going, particularly regarding the associated subgenera (Corna and Dommergues, 1995; Dommergues and Guiomar, 2011; Meister and Schlögl, 2013), so this taxonomic level is not used herein.    Age and Distribution:  Coroniceras is most commonly known from the upper part of the Involutum Zone, equivalent to the upper part of the Bucklandi Zone to the lowermost part of the 98  Semicostatum Zone in Europe. One species of Coroniceras (Coroniceras mutabile MACCHIONI, SMITH & TIPPER) occurs at the upper part of the Leslei Zone, in association with Caenisites (Macchioni et al., 2005). This genus has a wide range of distribution listed as follows:  Europe: Germany (Gruner, 1997); Hungary (Géczy and Meister, 2007); Italy (Pinna, 1985); Luxembourg (Colbach et al., 2003); Switzerland (Reisdorf et al., 2011); UK (Radley, 2002; Edmunds et al., 2003; Donovan et al., 2005); France (Guérin-Franiatte, 1966 & 1994); Austria (Dommergues et al., 1995); Spain (Braga et al., 1984); Turkey (Alkaya and Meister, 1995); Slovakia (Meister and Schlögl, 2013); Romania (Tomas and Pálfy, 2007); Ukraine (Gotsanyuk and Murali, 2009); Siberia (Shurygin et al., 2011). Asia: Guangdong (Wang and Smith, 1986) and Hong Kong (Lee, 1984; Nau, 1984); Vietnam (Sato and Westermann, 1991). North America: British Columbia (Frebold, 1951; Pálfy, 1991; Macchioni et al., 2006), ?Alberta (Hall, 2006) and ?Yukon (Poulton, 1991); Nevada (Smith, 1981; Taylor, 1998) and Alaska (Imlay, 1981); Mexico (Meister et al., 2005). South America: Chile (Quinzio-Sinn, 1987; Riccardi, 1992); Argentina (Riccardi et al., 1991); Peru (Erben and Haas, 1985). Elsewhere: New Zealand (Stevens, 2004).     Coroniceras multicostatum (SOWERBY, 1824) Page 181, Plate 5, Fig. 4.  * 1824 Ammonites multicostata SOWERBY, pl. 454. cf. 1867 Ammonites bisulcatus ORBIGNY – DUMORTIER, pl. 2.  1879 Ammonites multicostatus SOWERBY – REYNÈS, pl. 25, fig. 1-2  1929 Arietites bucklandi multicostatum SOWERBY – FIEGE, pl. 4, fig. 8.  1952 Coroniceras (Primarietites) multicostatum SOWERBY – Donovan, p. 736.  cf. 1955 Coroniceras (Primarietites) multicostatum SOWERBY – Donovan, 99  p. 30.  1966 Coroniceras multicostatum SOWERBY – GUÉRIN-FRANIATTE, pl. 29-32 (pl. 31 = holotype).  1990 Coroniceras multicostatum SOWERBY – CORNA et al., pl. 3, fig. 1.  1995 Coroniceras multicostatum SOWERBY – CORNA & DOMMERGUES, p. 26.  1997 Coroniceras multicostatum SOWERBY – CORNA et al., pl. 5, fig. 8-9.   2003 Coroniceras multicostatum SOWERBY – COLBACH et al., fig. 8.   2011 Coroniceras multicostatum SOWERBY – DOMMERGUES & GUIOMAR, p. 271, fig. 7; p. 272, fig. 8; p. 274, fig. 9; p. 277, fig. 10; pl. 1, fig. 1-2; pl. 2, fig.1-4; pl. 3, fig. 1-2; pl. fig. 1-3; pl. 1-6.  Material: 1 specimen from Last Creek preserved in a concretion in calcareous sandstone.   Measurements:  Specimen # D UD U WW WH WWWH PRHW L1-04-01 126.5 61.5 0.49 37.5 38.7 0.97 20  Description:  Medium sized, evolute form. Whorl shape subquadrate in inner whorls and gradually turn into subrectangular in outer whorls. The flanks are rather flat. The umbilical wall is inclined in inner whorls, but becomes vertical in the outer whorl. The height of the umbilical wall increases steadily with ontogeny. Venter convex, tricarinate-bisulcate. The median keel is slightly higher than lateral keel. The ribs are strong, straight and rursiradiate. They bend forward on both umbilical shoulder and ventrolateral shoulder. Some fairly strong tubercles occur at the ventrolateral end of the ribs. Some ribs show local interruption near the end of the body chamber.   100  Discussion:  Despite the wide intra-species variations discussed by Dommergues and Guiomar (2011), Coroniceras multicostatum differs from the similar species Coroniceras bisulcatum by having a higher rib frequency and rather concave ribs at comparable size (Meister and Schlögl, 2013). It differs from Coroniceras lyra in Guérin-Franiatte (1966) by its stronger, straighter and rursiradiate ribs which show a stronger projection on the ventrolateral shoulder. The difference with C. cf. lyra is discussed under C. cf. lyra.   Occurrence and Distribution:  This species occurs at the upper part of the Involutum Zone in Last Creek, British Columbia. Besides British Columbia, Canada, Coroniceras multicostatum SOWERBY is known from Europe: France (Guérin-Franiatte, 1966; Corna and Dommergues, 1995; Dommergues and Guiomar, 2011), UK (Palmer, 1972), Luxembourg (Colbach et al., 2003), ?Italy (Vialli, 1959), Austria (Meister and Friebe, 2003).   Locality: L1-04.    Coroniceras cf. lyra HYATT, 1867 Page 181, Plate 5, Figs. 2-3.   *cf. 1867 Coroniceras lyra HYATT, p. 78.  cf. 1879 Ammonites multicostatus SOWERBY – REYNÈS, pl. 25, fig. 26-28. cf. 1889 Coroniceras lyra HYATT – HYATT, p. 179, pl.4, figs. 1-17; pl. 5, fig. 1-3 cf. 1914 Arietites bucklandi SOWERBY – SCHMIDT, p. 5, pl. 1, fig. 3. cf. 1914 Arietites bisulcatus BRUGUIÉRE – SCHMIDT, p. 13, pl. 1, fig. 6; 101  pl. 2, fig. 1.  cf. 1923 Agassiceras reynesi SPATH, p. 72.  cf. 1924 Ammonites lyra HYATT – SPATH, p. 204.  cf. 1924 Ammonites sublyra SPATH, p. 204.  cf. 1926 Primarietites primitivus BUCKMAN, pl. 678.  cf. 1929 Arietites bucklandi SOWERBY – FIEGE, p. 75, pl. 3, fig. 6; pl. 4, fig. 7 cf. 1952 Coroniceras (Primarietites) reynesi SPATH – DONOVAN, p. 737, pl. 29, fig. 1.  cf. 1957 Primarietites reynesi SPATH – ARKELL et al., p. L237, fig. 262-2. cf. 1961 Coroniceras reynesi SPATH – DEAN et al., p. 451, pl. 65, fig. 5. cf. 1966 Coroniceras lyra HYATT – GUÉRIN-FRANIATTE, p. 134, fig. 35; p. 138, fig. 39; pl. 22-28.  cf. 1985 Coroniceras lyra HYATT – CORNA, pl. 7, fig. 1.  cf. 1989 Coroniceras lyra HYATT – MEISTER & LOUP, pl. 2, fig. 7; pl. 3,  fig. 2; pl. 4, fig. 2.   cf. 1995 Coroniceras lyra HYATT – DOMMERGUES et al., p. 186, pl. 3, fig. 3.  Materials: 1 in situ and 1 ex situ specimens from Last Creek preserved in concretions in sandstone.   Measurements:  Specimen # D UD U WW WH WWWH PRHW L1-03-04 FL    45.3 40.5 1.12  T 08-01 64.3 28.8 0.45 20.6 19.0 1.08 18  Description:  Small to potentially large sizes, moderately evolute. Whorl shape subquadrate, whorls slightly wider than high. Flanks rather flat, but becoming slightly convex with ontogeny. Umbilical wall is high and vertical from the nucleus. Venter is tricarinate-102  bisulcate, the median keel is as high as lateral keels, shouldered with wide sulci. Ribs straight, rectiradiate, strongly tuberculated, and gently swing forward onto the ventrolateral shoulder, and merge into the lateral keels. The suture line is typical for Arietitinae (Fig. 6-6). The ventral lobe (external lobe) is deeply retracted, much lower than the lateral lobe. The second lateral saddle is about the same size with the first lateral saddle but slightly higher.   Discussion:  The closest form of this species is Coroniceras lyra, but it differs from the Coroniceras lyra in Guérin-Franiatte (1966) by its slightly flatter venter and relatively more depressed whorl section. This species differs from Coroniceras multicostatum by its rectiradiate rather than rursiradiate ribs and flatter venter. It differs from C. mutabile by its stronger tubercles and lower rib frequency at comparable sizes.   Occurrence and Distribution:  This species occurs at the upper part of the Involutum Zone of Last Creek, British Columbia. Coroniceras lyra is a cosmopolitan taxon found mostly from Europe. It is currently known from the following areas:  Europe: UK (Donovan, 1952; Spath, 1924); France (Guérin-Franiatte, 1966); Germany (Fiege, 1929); Austria (Dommergues et al., 1995); Switzerland (Meister and Loup, 1989); Belgium (Mergen, 1984); Romania (Tibuleac, 2008). South America: Peru (Loughman and Hallam, 1982).  North America: British Columbia.   Locality: T 08.   103    Fig. 6-6 Septal suture of Coroniceras cf. lyra at WH=18mm, specimen T 08-01.   Coroniceras sp. Plate 5, Fig. 1.  Material: 1 specimen from Last Creek preserved in calcareous sandstone.   Measurements:  Specimen # D UD U WW WH WWWH PRHW L1-01-02 27.4 10.7 0.39 11.0 10.1 1.09 21  Description:  Small, moderately evolute form, with a relatively high whorl expansion rate for this genus. This species is one of the least evolute forms within the genus. The whorl section is sub-quadrate with flat flanks. The umbilical wall is vertical and fairly high for its size (<30mm). The venter is rather flat, and tricarinate-bisulcate. The height of the median keel is equivalent to that of lateral keels. The ribs are straight and rectiradiate, and swing forward at the ventrolateral shoulder. Some of the ribs are slightly flexuous. Rib frequency is high and increases during ontogeny. No tubercles. The end of the phragmocone becomes swollen, which might indicate the beginning of the aperture.    104  Discussion:  This species can be distinguished from other species of the genus at small size by its narrow umbilicus, high rib frequency and non-tuberculated mostly straight ribs. Eucoroniceras pygmaeum erected by Guérin-Franiatte (1966) is a similar species, but has much more flexuous ribs and a slightly higher umbilical ratio. Comparison with other species is difficult because of the size of the specimen.   Occurrence and Distribution:  This species occurs at the upper part of the Involutum Zone in Last Creek, British Columbia. It is currently known from British Columbia, Canada.   Locality: L1-01.      Coroniceras cf. mutabile MACCHIONI, SMITH & TIPPER, 2005 Page 183, Plate 6, Fig. 1, 3.   *cf. 2005 Coroniceras (Paracoroniceras) mutabile MACCHIONI, SMITH & TIPPER, p. 791, fig. 1, 1-3, fig. 2; p. 792, fig. 3, 1-4 (3-4, holotype); p. 793, fig. 4, 1-8; p. 794, fig. 5, 1-2.  cf. 2006 Coroniceras (Paracoroniceras) mutabile MACCHIONI, SMITH & TIPPER – MACCHIONI et al., p. 567, pl. 3, figs. 3-4; p. 568, text-fig. 3E  Materials: 1 specimen from Five Card Draw preserved in limestone and 1 specimen from Last Creek preserved in a concretion in calcareous sandstone.    105  Measurements:  Specimen # D UD U WW WH WWWH PRHW F3-14 39.0 18.2 0.47 12.2 10.5 1.16 21 L1-03-01 ~71.4 37.5 0.53 23.3 22.0 1.06 ~23  Description:  These two specimens are small, evolute, representing the inner whorls of C. mutabile. The whorl section is sub-quadrate. Flank fairly flat. The umbilical wall is low and inclined at small sizes, and becomes higher and vertical with ontogeny. The venter is slightly convex, tricarinate-bisulcate. The median keel is higher than lateral keels. Ribs rursiradiate, straight, sometimes slightly flexuous, and project forward on ventrolateral shoulder. Weak tubercles appear at the ventrolateral ends on the ribs.   Discussion:  These specimens are assigned to C. mutabile with reservation because the preservation doesn’t allow observations of the ontogenetic changes in ribbing patterns and whorl shape, which are important taxonomic characters. It differs from C. multicostatum by its weaker ribs and tubercles, higher rib frequency at comparable size, and more prominent median keel comparing to lateral keels. The difference with C. cf. lyra is discussed under C. cf. lyra.   Occurrence and Distribution:  This species is previously known to be associated with Caenisites in the upper part of the Leslei Zone (Macchioni et al., 2005, 2006), but its stratigraphic range is unknown. The specimens in this work were collected from the upper part of the Involutum Zone from Last Creek, British Columbia and Five Card Draw, Nevada. C. mutabile is known from British Columbia and Nevada.   Localites: F3-14, L1-03 106    Coroniceras charlesi DONOVAN, 1955 Page 183, Plate 6, Fig. 2.    1879 Ammonites gmuendensis OPPEL – REYNÈS, pl. 16, fig. 1-2. * 1955 Coroniceras (Paracoroniceras) charlesi DONOVAN, p. 12; p. 28, pl. 16, fig. 1-2. ? 1959 Paracoroniceras charlesi DONOVAN – REYMENT, pl. 1, fig. 2.  1966 Coroniceras (Paracoroniceras) charlesi DONOVAN – GUÉRIN- FRANIATTE (cum synonymy), p. 153-155, fig. 47-48; pl. 38-42.  1976 Arietites (Paracoroniceras) charlesi DONOVAN – SCHLEGELMILCH, p. 126, pl. 15, fig. 3.  1995 Coroniceras charlesi DONOVAN – CORNA & DOMMERGUES, p. 23, pl. 2, fig. 3; p. 28, fig. 4.  Material: 1 specimen from Last Creek preserved in calcareous sandstone.  Measurements:  Specimen # D UD U WW WH WWWH PRHW T 08-02 58.3 28.5 0.49 15.0 15.6 0.96 18  Description:  Small, evolute form with fairly wide umbilicus. Whorl section higher than wide sub-elliptical to sub-trapezoidal. Flanks slightly convex. Umbilical wall is vertical, moderate in height. Venter is convex, tricarinate-bisulcate. Both median keel and lateral keels are prominent. The median keel is higher than lateral keels. The ribs are strong and rursiradiate, slightly concave on the flanks and bend forward gently across the narrow ventrolateral shoulder, then merged into the lateral keels. No tubercles.  107   Discussion:  C. charlesi differs from C. multicostatum, C. cf. mutabile MACCHIONI, SMITH & TIPPER and C. cf. lyra by its more compressed whorl section, slightly concave rather than straight ribs, and absence of tubercles.   Occurrence and Distribution:  This species occurs in the upper part of the Involutum Zone, Last Creek, British Columbia. Coroniceras charlesi is known from UK (Spath, 1922b); Germany (Schlegelmilch, 1976); France (Corna and Dommergues, 1995); Romania (Tibuleac, 2008); British Columbia, Canada; ?Alaska (Imlay, 1981), USA; Argentina (Riccardi et al., 1991).   Locality: T 08.    Coroniceras cf. involutum TAYLOR 1998 Page 185, Plate 7, Fig. 1.  *cf. 1998 Coroniceras involutum TAYLOR, p. 481, fig. 13. 8, 9; p. 483, fig. 14. 7, 8.  Material: 1 giant specimen from Five Card Draw preserved in limestone.   Measurements:  Specimen # D UD U WW WH WWWH PRHW F1-01 436 206.5 0.47 ~110 137 ~0.80 17   108  Description:  This incomplete specimen already reaches a size over 40cm, moderately evolute (U=0.47). The inner whorls are more evolute than the massive and quickly expanding outer whorl. The whorl section is sub-quadrate, but becomes sub-rectangular and compressed on the last half of the outer whorl. Flanks fairly flat. The umbilical wall is moderately high and nearly vertical, except in the first few whorls. Venter is convex, tricarinate-bisulcate with strong keels. The median keel is higher than lateral keels, sulci fairly wide. The rib frequency is high (PHRW≈21) on the inner whorls (D<150 m), and drops to 17 on the outer whorl. The ribs are rursiradiate, bear tubercles and gently bend forward onto the ventrolateral shoulder. Rib strength decreases slowly with growth.   Discussion:  This species is closest to Coroniceras involutum TAYLOR, but less evolute, and the sulci on the venter don not become shallower with ontogeny. Coroniceras luningense TAYLOR and Coroniceras volcanoense TAYLOR can also reach the same size, but both are more evolute and their ribs are not tuberculate.   Occurrence and Distribution:  This species occurs near the base of the section at Five Card Draw, Nevada, from the upper part of the Involutum Zone. Coroniceras involutum is currently known from Nevada, USA.   Locality: F1-01.  109  Genus ARNIOCERAS Hyatt, 1867  Type species: Arnioceras cuneiforme HYATT, 1867  Synonymy: Arniotites WHITEAVES, 1889; Armioceras SPATH, 1919, nom. null.; Eparnioceras SPATH, 1924; Arniococeas ARKELL,  1951, nom. null.; Burkhardticeras LOPEZ 1967; Laevispirus VENTURI & NANNARONE, 2002.   Description:  Evolute forms with compressed whorls. Whorl section mostly subrectangular to subquadrate, sometimes oval or subrounded. The umbilical ratio is 45%~60% at diameters under 5cm, and typically over 50% at diameters over 5cm. Nucleus usually smooth up to 5~15mm. Ribs are sharp, dense, straight, rectiradiate or rursiradiate, and may project onto the venter to abut against the lateral keels (except A. miserabile and A. laevissimum, which are smooth). The venter bears a sharp median keel shouldered by sulci and lateral keels in most species. Suture is relatively simple, with low and deeply incised lateral lobes.   Remarks:  Arnioceras is one of the most common taxon in Sinemurian. The most important characters are the smooth stage, sharp and straight ribbing and ceratitic-like suture. A large number of species have been illustrated, which makes the identification of the species difficult. Corna and Dommergues (1995) complained about the redundancy of this difficulty and proposed a semi-quantitative method to study the ontogeny and morphologic variability, the concept of which is adopted here whenever preservation allows. Comparisons of the measurements of this work, the type specimens and some major work are also commonly used to help with identification. Major treatments of this genus are given by Jaworski (1931) and Guérin-Franiatte (1966).  110   Age and Distribution:  Arnioceras is a cosmopolitan genus with a long stratigraphic range in Sinemurian, from the upper part of the Involutum Zone to the lower part of the Carinatum Zone, equivalent to from the top of the Bucklandi Zone to the Lower Obtusum Zone in Northwest Europe. It has a wide geographic distribution and is typically know from the following areas:  Europe: France (e.g., Guérin-Franiatte, 1966); Germany (e.g., Arp et al., 2000); UK (e.g., Howarth, 2002); Spain (e.g., Braga et al., 1984); Hungary (e.g., Géczy and Meister, 2007); Italy (e.g., Venturi and Nannarone, 2002); Switzerland (e.g., Reisdorf et al., 2011); Luxembourg (e.g., Colbach et al., 2003); Sweden (Reyment, 1959). North America: British Columbia (e.g., Pálfy et al., 1994), Yukon and Northwest Territories (e.g., Frebold and Poulton, 1977), Alberta (e.g., Poulton, 1991); Alaska (e.g., Imlay, 1981), California (e.g., Sanbord, 1960), Nevada (e.g., Taylor et al., 2001); Mexico (e.g., Meister et al., 2005). South America: Chile (e.g., Quinzio-Sinn, 1987), Argentina (e.g., Riccardi et al., 1991), Peru (e.g., Erben and Haas, 1985), Ecuador (e.g., Dommergues et al., 2004). Asia: Turkey (e.g., Cope, 1991); Tibet (e.g., Wang and He, 1981), Guangdong (e.g., Wang and Smith, 1986); Vietnam (e.g., Meister et al., 2004). Africa: Morocco (e.g., El-Harriri et al., 2010); Tunisia (e.g., Rakús and Guex, 2002). Elsewhere: New Zealand (e.g., Stevens, 2004); New Caledonia (e.g., Meister et al., 2010).    Arnioceras ceratitoides (QUENSTEDT, 1848) Page 183, Plate 6, Figs. 4-7; Page 187, Plate 8, Figs. 1-3.   * 1848 Ammonites ceratitoides QUENSTEDT, p. 239, pl. 19, fig. 13.  1856 Ammonites ceras GIEBEL – HAUER, p. 25, pl. 6, figs. 4-6.   1885 Ammonites ceratitoides QUENSTEDT, p. 105, pl. 13, fig. 23. 111   1887 Ammonites ceratitoides var. densicosta STEFANI, p. 66, pl. 4, figs. 8, 9.   1899 Arnioceras ceratitoides QUENSTEDT – BONARELLI, p. 61, pl. 8, figs. 4, 5.   1889 Arnioceras humboldti HYATT, p. 173, figs. 31-33.   1902 Arnioceras ceratitoides QUENSTEDT – FUCINI, p. 164, pl. 14, fig. 13; pl. 15.   1917 Arnioceras ceratitoides QUENSTEDT – TILMANN, p. 661, pl. 21, fig. 3.  ? 1942 Arnioceras cf. ceratitoides QUENSTEDT – KOVACS, pl. 4, fig. 5.   1963 Arietites ceratitoides QUENSTEDT – WILLARD, p. 213, fig. 1, lower specimen.   1967 Arnioceras ceratitoides QUENSTEDT – CASSINIS & CANTALUPPI, p. 60, pl. 7, figs. 4, 5.   1972 Arnioceras ceratitoides QUENSTEDT – GÉCZY, p. 31, fig. 2.   1973 Arnioceras sp. ex gr. ceratitoides QUENSTEDT – GEYER, p. 50, pl. 3, fig. 4; pl. 4, figs. 1, 2.  ? 1974 Arnioceras sp. ex gr. ceratitoides QUENSTEDT – GEYER, p. 537, fig. 6.   1976 Arnioceras ceratitoides QUENSTEDT – SCHLEGELMILCH, p. 48, pl. 20, fig. 6.   1979 Arnioceras sp. ex gr. ceratitoides QUENSTEDT – GEYER, p, 208, fig. 5c.   1981 Arnioceras ceratitoides QUENSTEDT – SMITH, pl. 1, fig. 6, 7; text-figs. 6-3.  ? 1984 Arnioceras ceratitoides QUENSTEDT – BRAGA, MARTIN-ALGARRA & RIVAS, pl. 1, fig. 15.  ? 1985 Arnioceras ceratitoides QUENSTEDT – BRAGA, MARTIN-ALGARRA & RIVAS, pl. 1, fig. 6.   1986 Arnioceras ceratitoides QUENSTEDT – WANG & SMITH, p. 1079, fig. 4.1-4.3; p. 1080, fig. 5.  112  ? 1991 Arnioceras ex gr. ceratitoides QUENSTEDT – PÁLFY, pl. 10, fig. 1-2.  cf. 2001 Arnioceras humboldti HYATT – TAYLOR, GUEX & RAKÚS, p. 405, pl. 1, fig. 7; p. 411, pl. 3, figs. 6-7.   2007 Arnioceras ceratitoides QUENSTEDT sensu FUCINI – GÉCZY & MEISTER, pl. 17, figs. 6, 7  Materials: 28 flattened specimens preserved in silty shale and black shale in Five Card Draw, and 5 specimens from Last Creek well preserved in calcareous sandstone and shale.   Measurements:  Specimen # D UD U WH PRHW L1-06 ~65.3 34.5 0.53 17.8 ~24 L2-04 37.5 21.3 0.57 10.1 20 L2-03-07 ~45.7 22.5 0.49 13.5 20 L2-06-01 43.5 21.7 0.50 12.6 18 F2-01-01 48.0 20.4 0.43 17.1 16 F1-27-07-1 ~75.6 36.5 0.48 ~23.2 23 F1-27-10-2 58.0 26.2 0.45 19.3 20 F1-27-23 ~49.5 ~23.0 0.46 16.6 27 F1-27-40-1 42.6 20.1 0.47 13.5 18 F1-27-51 30.6 13.6 0.44 10.3 18 F1-27-63-1 ~29.3 12.1 0.41 9.2 21 F1-27-64-2 ~28.5 12.4 0.44 8.9 21 F1-27-64-3 ~51.5 23.5 0.46 16.5 20 F1-27-65-1 37.7 14.7 0.39 13.1 17 F1-27-66 ~53.4 ~24.5 0.46 16.5 22 F1-27-22 ~55.5 24.5 0.44 ~18.0 18 F1-27-38 ~54.0 24.3 0.45 17.0 20 F1-27-35 ~55.0 25.5 0.46 16.0 22 F1-11-21 ~26.3 13.0 0.49 ~7.0 18 F1-11-15-1 24.5 11.8 0.48 7.5 19 F1-21-01 ~66.0 ~34.0 0.52 ~19.5 24 F1-32-07-1 30.5 14.0 0.46 10.0 19 F1-33 ~92.6 43.5 0.47 27.5 ~19  Description:  Size varies from a few centimeters to over ten centimeters. Umbilical ratio is approximately 45%. Smooth up to 10~15 mm. Ribs are straight and sharp, sometimes 113  slightly swollen ventrally. The rib density stays fairly steady during ontogeny (Fig. 6-8). The ribs remain straight even at large sizes, but the ventral end may project forward slightly. The venter possesses a prominent median keel, shouldered by sulci and lateral keels. Flanks are flat, umbilical wall is low. The suture has broad and long elements (Fig. 6-7). The first and second lateral saddles are high and simple, the lateral and suspensive lobes are low and serrated.     Fig. 6-7 Septal sutures of Arnioceras ceratitoides at WH≈23.2 mm (a) and WH=10 mm (b). Specimen: a. F1-27-07-01, b. F2-02-06-12.   Discussion:  The specimens from Nevada are generally the same as other reported Arnioceras ceratitoides except their slightly larger smooth stage. The smooth umbilicus of Arnioceras semiscostatum is similar, but the rib density is much lower (PRHW is about 15) at comparable sizes. The species Arnioceras humboldti was assigned to A. ceratitoides by Smith (1981). The Arnioceras cf. humboldti (Macchioni et al., 2006) also has a similar smooth stage, but presents a slightly higher WH/D ratio (~0.33).   Occurrence and Distribution:  In Five Card Draw, Nevada, it occurs at the lower part of Five Card Draw Member, Sunrise Formation. In North America, Arnioceras ceratitoides ranges from uppermost Involutum Zone to the lowermost Carinatum Zone. While in Europe, it is one of the characteristic taxa of Semicostatum Zone, and possibly ranges to middle Obtusum Zone 114  (Géczy and Meister, 2007). Arnioceras ceratitoides is a cosmopolitan species. It is known from the following continents:  Europe: France (Guérin-Franiatte, 1966); Germany (Schlegelmilch, 1976); Hungary (Géczy and Meister, 2007); Switzerland (Reisdorf et al., 2011); Spain (Braga et al., 1984), Austria (Schlegelmilch, 1976), Italy (Canavari, 1899); Romania (Tibuleac, 2005); Slovakia (Meister et al., 2011). Africa: Morocco (Dresnay, 1988). North America: Nevada (Smith, 1981; Taylor et al., 2001), Oregon (Smith, 1981), British Columbia (Pálfy et al., 1994; Johannson et al., 1997); Mexico (Erben, 1956; Meister et al., 2005). South America: Peru (Suzuki et al., 2002); Ecuador, Chile and Columbia (Riccardi et al., 1990). Asia: Guangdong (Wang and Smith, 1986); possibly Japan (Sato, 1992); Georgia (Topchishvili, 1998).   Localities: F1-03, F1-07, F1-08, F1-11, F1-20, F1-21, F1-25, F1-27, F1-33, F1-32, F2-03; F2-01, F2-06, F2-08; L1-06, L2-03, L2-04, L2-06.     115      Fig. 6-8 Shell size (D), whorl height (WH) and rib frequency (PHRW) plots against umbilical diameter (UD) of Arnioceras ceratitoides, compared with that of Schlegelmilch (1976), Géczy & Meister (2007), Smith (1981), Braga et al. (1984), Wang & Smith (1986).    Arnioceras arnouldi (DUMORTIER, 1867) Page 187, Plate 8, Figs. 4-6; Page 189, Plate 9, Fig. 4.  0.030.060.090.0120.00.0 10.0 20.0 30.0 40.0 50.0DSchlegelmilch, 1976Gèzy&Meister,2007Smith,1981Braga et al.,1984Wang&Smith,1986FCDLC0.0010.0020.0030.0040.0050.000.0 10.0 20.0 30.0 40.0 50.0WH0102030400.0 10.0 20.0 30.0 40.0 50.0PRHWUD116    * 1867 Ammonites arnouldi DUMORTIER, pl.5, figs. 1-2; pl. 6, figs. 1-6. ? 1869 Ammonites nevadanus GABB, p. 6, pl. 3, fig. 1.  1878 Arietites douvillei BAYLE, pl. 76, figs. 2-3.   1956 Arnioceras arnouldi DUMORTIER – ERBEN, pl. 32, fig. 1.   1966 Arnioceras arnouldi DUMORTIER – GUÉRIN-FRANIATTE, pl. 150-152.   1967 Arnioceras arnouldi DUMORTIER – CASSINIS & CANTALUPPI, p. 60, pl. 7, figs. 2-3.  1968 Arnioceras arnouldi DUMORTIER – FREDERICI, p. 114, figs. 3d-f; p. 116, fig. 4c.  ? 1979 Arnioceras cf. arnouldi DUMORTIER – GEYER, p. 207, fig. 5d.  1981 Arnioceras arnouldi DUMORTIER – SMITH, p. 135, pl. 1, figs. 3-5, text-fig. 6-2.  1981 Arnioceras arnouldi DUMORTIER – WANG & HE, pl. 2, figs. 11-12.  1991 Arnioceras arnouldi DUMORTIER – PÁLFY, pl. 8, fig. 3; pl. 9, figs. 1-2.  1993 Arnioceras aff. arnouldi DUMORTIER – DOMERGUES, pl. 1, figs. 3-5.  1994 Arnioceras arnouldi DUMORTIER – PÁLFY et al., p. 1, fig. 2. ? 2001 Arnioceras aff. arnouldi DUMORTIER – TAYLOR et al., pl. 1, fig. 8; pl. 2, figs. 1, 2, 11. ? 2002 Arnioceras arnouldi DUMORTIER – RAKÚS & GUEX, pl. 12, fig. 3.  2007 Arnioceras arnouldi DUMORTIER – GÉCZY & MEISTER, pl. 16, fig. 5; pl. 17, fig. 4.  Materials: 16 specimens from Five Card Draw and 4 specimens from Five Card Draw preserved in limestone and shale.   117  Measurements:  Specimen # D UD U WH WW PRHW F3-07 108.6 67.9 0.63 21.9 20.9 23 F3-01 85.5 50.6 0.59 18.2  23 F3-03 78.3 45.8 0.58 17.5  23 F3-04 48.8 27.7 0.57 10.9 10.3 19 F1-03-00 143.7 83.4 0.58 32.9 30.4 30  Description:  Size can reach over 150mm in diameter. Umbilicus wide and open. The umbilical ratio is around 0.55~0.65, fairly high for the genus (Fig. 6-9). Whorl section sub-rectangular to elliptical. Flanks convex to rather flat. Umbilical wall is low and umbilical shoulder rounded. Ribs are strong, and project forward on ventrolateral end markedly. The ribs become rursiradiate and concave with growth. Rib frequency increases steadily with ontogeny (Fig. 6-9). The venter is convex with a prominent, sharp median keel, shouldered with deep sulci and less prominent lateral keels.   Discussion:   The holotype of Arnioceras arnouldi selected by Dumortier (1867) was refigured by Guérin-Franiatte (1966), who also figured and subsequently designated the lectotype and paralectotypes. It differs from A. ceratitoides and A. semicostatum by its stronger and forward-projecting ribs. Also, A. ceratitoides has a higher rib frequency and a higher whorl expansion rate; while A. semicostatum has smaller sizes, straighter ribs and a lower umbilical ratio. A. oppeli differs from A. arnouldi by its flatter and non-deeply sulcate venter, a lower rib frequency, and straighter ribs.   Occurrence and Distribution:  This species is a relatively long-ranging, occurring from the upper part of the Involutum Zone to the lower part of the Carinatum Zone in both British Columbia and 118  Nevada. Arnioceras arnouldi is known from the following areas:  Europe: France (Guérin-Franiatte, 1966); Hungary (Géczy & Meister, 2007); Italy (Federici, 1968); North America: Nevada (Smith, 1981); British Columbia (Pálfy et al., 1994); Mexico (Erben, 1956); South America: Peru (Geyer, 1979); Asia: Tibet (Wang and He, 1981).   Localities: F3-01, F3-03, F3-04, F3-07; F1-02, F1-03, F1-06, F1-07, F1-09, F1-05, F1-19, F1-23, F1-27, F1-32.   119      Fig. 6-9 Shell size (D), whorl height (WH) and rib frequency (PRHW) plots of Arnioceras arnouldi, compared with Guérin-Franiatte (1966, refigured holotype and lectotype figured therein).    Arnioceras cf. arnouldi (DUMORTIER, 1867) Page 189, Plate 9, Fig. 3. 30.070.0110.0150.0190.020.0 40.0 60.0 80.0 100.0DGuérin-Franiatte, 1966HolotypeLectotypeFCDLC4.013.022.031.040.020.0 40.0 60.0 80.0 100.0WH81624324020.0 40.0 60.0 80.0 100.0PRHWUD120   Materials: 2 specimens from Last Creek preserved in calcareous siltstone and shale.   Measurements:  Specimen # D UD U WW WH PRHW L2-07-02 ~48.6 24.4 0.50  ~14.7 ~17  Description:  The preservation of the two specimens is poor. Nucleus smooth, evolute, flanks slightly convex. The ribs are strong and fairly sharp, projecting forward on the ventrolateral end. The venter is convex and has a strong and prominent median keel, shouldered with sulci.   Discussion:  The specimens resemble Arnioceras arnouldi as far as preservation allows comparison, and the measurements are quite similar with that of the holotype. It cannot be confidently separated from A. oppeli, given the possible errors of the measurements. Arnioceras oppeli could have a similar ribbing pattern at the same size but more likely to have a lower rib frequency.   Occurrence and Distribution:  This species occurs from upper part of the Leslei Zone. For distribution, see Arnioceras arnouldi.   Locality: L2-07.    Arnioceras semicostatum (YOUNG & BIRD, 1828) 121  Page 189, Plate 9, Figs. 1-2.    * 1828 Ammonites semicostatus YOUNG & BIRD, pl. 12, fig. 10.  1889 Arnioceras semicostatum YOUNG & BIRD – HYATT, pl. 2, fig. 15.  1902 Arnioceras semicostatum YOUNG & BIRD – FUCINI, pl. 22, figs. 1-3, 5-11, 13, 15.  1966 Arnioceras semicostatum YOUNG & BIRD – GUÉRIN-FRANIATTE (cum synonymy), p. 256, text-fig. 123; pl. 137, figs. 1-5. cf. 1985 Arnioceras cf. semicostatum YOUNG & BIRD – ERBEN and HAAS, pl. 3, fig. 5.  1987 Arnioceras semicostatum YOUNG & BIRD – QUINZIO-SINN, pl. 2, fig. 15.  1976 Arnioceras semicostatum YOUNG & BIRD – SCHLEGELMILCH, pl. 21, fig. 5 (refigured holotype).  1991 Arnioceras cf. semicostatum YOUNG & BIRD – COPE, pl. 3, fig. 6.  cf. 2001 Arnioceras cf. semicostatum YOUNG & BIRD – TAYLOR et al., pl. 2, figs. 5, 6, 8.  ? 2007 Arnioceras gr. semicostatum YOUNG & BIRD – GÉCZY & MEISTER, pl. 15, fig. 9.   Materials: 3 specimens from Last Creek preserved in calcareous sandstone.   Measurement:  Specimen # D UD U WW WH WWWH PRHW T 10 56.5 29.0 0.51 15.2 14.5 0.95 17 T 03-01 75.3 40.8 0.54 16.1 18.5 0.87 18  Description:  Medium sized, evolute forms. Whorl section subquadrate to subrectangular. Flanks slightly convex. Umbilical wall is inclined and rather rounded. The venter is convex and 122  bears a sharp and prominent median keel, shouldered with fairly deep sulci and lateral keels. The nucleus is smooth up to about 1cm. Ribs are straight and sharp, rectiradiate to slightly rectiradiate. The ribs get swollen at ventrolateral shoulder, end right before reaching the lateral keels, and may slightly project forward.   Discussion:  Fucini (1902) illustrated quite a few specimens of A. semicostatum, showing a large morphologic variability, and some of the specimens were later assigned to other species. A comprehensive treatment of this species is given by Guérin-Franiatte (1966). A. semicostatum differs from A. ceratitoides by its lower rib frequency, and the ribs are not as sharp or straight as that of A. ceratitoides. The difference with A. arnouldi is discussed under A. arnouldi.   Occurrence and Distribution:  The specimens were collected ex situ near the headwaters of the Last Creek, probably from the upper part of the Involutum Zone to the lower part of the Leslei Zone. A. semicostatum is a cosmopolitan taxon which has been reported from the following areas:  Europe: UK (Schlegelmilch, 1976); France (Guérin-Franiatte, 1966); Austria (Mandl et al., 2010); Hungary (Géczy and Meister, 2007); Italy (Fucini, 1902); Turkey (Cope, 1991). North America: Alaska (Imlay, 1981), Nevada (Taylor et al., 2001). South America: Peru (Suzuki et al., 2002); Chile (Quinzio-Sinn, 1987).   Localities: L1-08, T 03, T 10.    Arnioceras cf. oppeli GUÉRIN-FRANIATTE, 1966 Page 191, Plate 10, Fig. 1.  123    *cf. 1966 Arnioceras oppeli GUÉRIN-FRANIATTE (cum synonomy), p. 267, pl. 143, fig. 1-3.  1968 Arnioceras cf. oppeli GUÉRIN-FRANIATTE – FEDERICI, p. 122, fig. 4e-f. cf. 1976 Arnioceras oppeli GUÉRIN-FRANIATTE – SCHLEGELMILCH, p. 48, pl. 20, fig. 5.   1981 Arnioceras cf. oppeli GUÉRIN-FRANIATTE – SMITH, pl. 2, fig. 1, 4.   1987 Arnioceras cf. oppeli GUÉRIN-FRANIATTE – QUINZIO SINN, pl. 2, fig. 13.  cf. 1991 Arnioceras cf. oppeli GUÉRIN-FRANIATTE – PÁLFY, pl. 8, fig. 1.  Materials: 1 fragment from Last Creek preserved in calcareous shale.   Measurements:  Specimen # D UD U WW WH WWWH PRHW L2-05 ~90.0 ~44.0 0.49  ~26.5    Description:  The specimen represents about half of the external whorl, medium sized, evolute. Flanks are rather flat. Ribs are sharp, straight, distant, and rectiradiate, but do not project forward onto the venter, which resembles Arnioceras even though the smooth nucleus is not available. The venter is flat, and bears a prominent and sharp keel, but not as deeply sulcate as in other species of Arnioceras.   Discussion:  A detail treatment of Arnioceras oppeli is given by Guérin-Franiatte (1966), who erected this species and designated the holotype from the work of Jaworski (1931). This specimen is closest to Arnioceras oppeli, by its flat venter and sparse ribbing pattern, which 124  distinguishes it from other species of Arnioceras found in Last Creek and Five Card Draw.   Occurrence and Distribution:  This specimen occurs at the upper part of the Leslei Zone in Last Creek. A. oppeli is a characteristic species of the Semicostatum Zone and Lower Turneri Zone in Europe (e.g., Corna, 1987). It is also known from the Bucklandi Zone in Italy (Federici, 1968). Géczy (1972) reported A. aff. oppeli from the Obtusum Zone of Hungary. It is a cosmopolitan taxon and has been reported form the following areas:  Europe: UK, France, Germany (Guérin-Franiatte, 1966); Switzerland (Reisdorf et al., 2011); Italy (Federici, 1968); Hungary (Géczy, 1972b). North America: British Columbia (Pálfy, 1991); Nevada (Smith, 1981); ?Mexico (Meister et al., 2005). South America: Chile (Quinzio-Sinn, 1987).   Locality: L2-05.    Arnioceras densicosta (QUENSTEDT, 1884) Page 191, Plate 10, Figs. 2-3.    1879 Ammonites geometricus OPPEL – REYNÈS, pl. 14, figs. 5-6.  * 1884 Ammonites falcaries densicosta QUENSTEDT, p. 100; pl. 13, fig. 7.   1902 Arnioceras pluriplicatum n. sp. FUCINI, p. 155; pl. 25, figs. 4-5.    1955 Arnioceras cf. densicosta QUENSTEDT – DONOVAN, p. 27.  1966 Arnioceras cf. densicosta QUENSTEDT – GUÉRIN-FRANIATTE, p. 266, text-fig. 130; p. 267, text-fig. 131; pl. 142, figs. 1-3.  1981 Arnioceras cf. A. densicosta QUENSTEDT – IMLAY, p. 33; pl. 5, figs. 9-11, 16-24.  1985 Arnioceras pluriplicatum FUCINI – BRAGA et al., p. 96; pl. 1, fig. 3. 125   1987 Arnioceras cf. densicosta QUENSTEDT – QUINZIO-SINN, pl. 2, fig.14.    1991 Arnioceras cf. densicosta QUENSTEDT – PÁLFY, pl. 7, fig. 7.  Materials: 3 specimens from Last Creek preserved in calcareous sandstone and shale, 1 external mold and 1 flatten specimen from Five Card Draw preserved in limestone and shale, 2 specimens from Five Card Draw well preserved in limestone.   Measurements:  Specimen # D UD U WW WH WWWH PRHW L1-09 42.1 20.2 0.48  11.6  24 L1-10-01 ~21.2 10.8 0.51  5.8  22 F1-07 ~86.0 51.6 0.60  18.0  24 F2-16-01 23.5 10.4 0.44  7.5  23 F3-06 ~24.2 10.8 0.45 8.7 9.1 0.96 ~24 F3-02 25.1 12.9 0.51 5.8 7.0 0.83 20  Description:  Small to medium sized, evolute forms. Flanks are slightly convex. Whorl section elliptical. Umbilical wall is low. Venter is convex, tricarinate-bilsulcate, median keel more prominent than lateral keels. The nucleus is smooth up to 10~15mm. Ribs are straight to slightly concave, gently rursiradiate, and do not project forward markedly. Rib density is very high (PHRW >20), and increases slightly with growth at first then remains stable.   Discussion:  The specimens of this study are in good agreement with the lectotype of Arnioceras densicosta except the sharpness of the ribs. FUCINI’s A. pluriplicata is indistinguishable from A. densicosta and was synonymized into A. densicosta (Pálfy, 1991). A. densicosta differs from all other species in Arnioceras in this work by being more densely ribbed at comparable sizes.  126   Occurrence and Distribution:  Arnioceras densicosta occurs from the top of the Involutum Zone to Leslei Zone in Last Creek and Five Card Draw in this work, while in Europe, A. densicosta is one of the characteristic taxa from the Semicostatum Zone. It has been reported from the following areas:  Europe: Germany, France (Guérin-Franiatte, 1966); Italy (Fucini, 1902); Spain (Braga et al., 1985). North America: British Columbia (Pálfy, 1991); Alaska (Imlay, 1981), Nevada. South America: Chile (Guérin-Franiatte, 1966).   Localities: L1-05, L1-09, L1-10, F1-07, F2-16, F3-02, F3-06.    Arnioceras miserabile (QUENSTEDT, 1858) Page 191, Plate 10, Figs. 6-10; Page 193, Plate 11, Figs. 1-4.    cf. * 1858 Ammonites miserabilis QUENSTEDT, p. 71, pl. 8, fig. 7.  1879 Ammonites geometricus var. hartmanni OPPEL – REYNÈS, pl. 15, figs. 3-4.  cf. pars 1884 Ammonites miserabilis QUENSTEDT – QUENSTEDT, p. 106, pl. 13, figs. 27-29.   1886 Arietites ambiguus nov. sp GEYER, p. 252, pl. 3, figs. 11-12.  pars 1889 Arnioceras miserabile HYATT, pl. 2, figs. 4-5 (non fig. 7).  cf. 1902 Arnioceras miserabile QUENSTEDT – FUCINI, pl. 16, fig. 10.   1918 Arnioceras flavum BUCKMAN, pl. 31, figs. 2a, 2b.  cf. 1942 Arnioceras miserabile QUENSTEDT – KOVACS, pl. 3, fig. 7.  1955 Arnioceras miserabile QUENSTEDT – DONOVAN, p. 28.  cf. 1956 Arnioceras miserabile QUENSTEDT – ERBEN, pl. 37, fig. 18. cf. 1966 Arnioceras miserabile QUENSTEDT – GUÉRIN-FRANIATTE, 127  pl. 136, figs. 1 (= QUENSTEDT 1884, pl. 13, fig. 27), 2 (= QUENSTEDT 1884, pl. 13, fig. 28), 3-4. cf. 1973 Arnioceras miserabile QUENSTEDT – GEYER, p. 52, pl. 4, fig. 6. cf. 1976 Arnioceras miserabile QUENSTEDT – GEYER, pl. 1, fig. 4 (refigured GEYER 1973, pl. 4, fig. 6).   1976 Arnioceras miserabile QUENSTEDT – SCHLEGELMILCH, p. 49, pl. 21, fig. 5 (=QUENSTEDT 1884, pl. 13, fig. 27). non 1976 Arnioceras n. sp. aff. miserabile QUENSTEDT – GEYER, pl. 1, fig. 5. (refigured GEYER 1973, pl. 4, fig. 5).   1981 Arnioceras miserabile QUENSTEDT – SMITH, pl. 2, figs. 2-3.  1985 Arnioceras cf. miserabile QUENSTEDT – PRINZ, pl. 3, fig. 6.  1987 Arnioceras cf. miserabile QUENSTEDT – QUINZIO SINN, pl. 3, fig. 2.   1990 Arnioceras cf. miserabile QUENSTEDT – DOMERGUES, MEISTER & METTRAUX, pl. 1, figs. 11-12.  cf.  1991 Arnioceras miserabile QUENSTEDT – PÁLFY, pl. 7, fig. 2.  pars 1997 Arnioceras sp. gr. C – CORNA et al., pl. 7, fig. 3 (non 14-17).  cf. 1997 Arnioceras miserabile QUENSTEDT – JOHNANNSON, SMITH & GORDEY, pl. 1, fig. 1a.  cf. 2000 Arnioceras miserabile QUENSTEDT – SCHUBERT & METZDORF, pl. 3, fig. 3. cf. 2002 Arnioceras miserabile QUENSTEDT – VENTURI & NANNARONE, pl. 3, fig. 21.  cf. 2002 Arnioceras miserabile QUENSTEDT – MEISTER, BLAU, SCHLATTER & SCHMIDT-EFFING, pl. 3, fig. 7.   2004 Arnioceras cf. miserabile QUENSTEDT – DOMMERGUES, MEISTER & JAILLARD, pl. 1, fig. 23.   2007 Arnioceras cf. miserabile QUENSTEDT – GÉCZY & MEISTER, pl. 15, figs. 7, 8.   128  Materials: 8 specimens from Last Creek preserved in calcareous sandstone and shale, 17 specimens from Five Card Draw preserved in limestone and shale.   Measurements:  Specimen # D UD U WW WH WWWH EXP F3-05 20.8 9.9 0.48 4.4 5.3 0.83 1.76 F1-27-01 23.5 8.5 0.36  8.3  1.88 F1-11-05 37.2 13.8 0.37  6.9   F1-11-08-02 25.6 10.2 0.40  8.1   F1-27-68-03 23.2 9.5 0.41  8.0   F1-27-02 26.4 11.1 0.42  9.4  2.39 F1-27-41 32.2 14.8 0.46  9.8  2.00 F1-27-11 39.5 18.4 0.47  10.0   F1-27-04-1 28.5 13.4 0.47  9.6  2.36 F1-20-02-1 21.2 10.1 0.48  7.0  1.39 F1-27-04-2 32.4 15.7 0.48  11.3   F1-30-01 26.7 13.0 0.49  7.5   F1-20-01 28.2 14.0 0.50  7.2   F1-27-68-02 25.0 12.8 0.51  7.4   F1-27-49 34.9 20.0 0.57  8.0   L2-07-01 21.2 9.2 0.43  5.9  1.62 T 11-01 13.0 6.3 0.48 2.3 3.5 0.66 1.54 T 11-02 20.4 10.2 0.50 4.0 5.6 0.71 2.03 T 13-01 19.0 8.0 0.42 4.5 5.8 0.78 1.85 T 13-02 22.0 9.8 0.45 5.2 6.5 0.80 1.68 T 11-05 16.5 6.9 0.42 3.7 5.3 0.70 1.89 T 11-06 25.3 12.8 0.51 4.9 6.5 0.75 1.58 T 11-07 29.3 15.2 0.52 5.0 6.6 0.76 1.23  Description:  Small evolute forms with smooth shells. Whorl section compressed, elliptic to high elliptic. Flanks slightly convex to rather flat. Umbilical wall is very low. The venter is weakly acute. No ornamentation visible on shell surface. Venter is fastigate to acute, and bears a non-sulcate keel. The keel is very low and weak at small sizes, but becomes more prominent with growth. Most of the specimen has no ornamentations at all, some have very fine striae. Whorl expansion rate generally varies from 1.5 to 2.0 (Fig. 6-10).  129   Discussion:  Arnioceras miserabile (when D>15 mm) is readily distinguishable from other species of the same genus with ribbing. Though it can be differentiated from A. n. sp. A given good preservation (see Arnioceras n. sp. A), it is possible that A. miserabile is the microconch of some other larger species, as Donovan et al. (2005) suggested. A. flavum is a similar smooth species, and was considered a synonymy of A. miserabile (Géczy and Meister, 2007). A. laevissimum is also a small smooth form but is poorly documented and understood, and its precise stratigraphic range of which is unknown, same problem with Hypasteroceras. Braga et al. (1984) recorded a species Hypasteroceras ? laevissimum which has more convex flanks and is less evolute than A. miserabile. Macchioni et al. (2006) described several specimens of Hypasteroceras montii, all of which are one magnitude larger in size than A. miserabile, and the umbilical wall is high from nucleus.   Occurrence and Distribution:  A. miserabile occurs at the Leslei Zone and both Last Creek and Five Card Draw. It is one of the characteristic taxa of the Semicostatum Zone in Europe. There are reports of this species from the following areas:  Europe: UK (Donovan et al., 2005), Germany, France (Guérin-Franiatte, 1966 and thererin); Switzerland (Dommergues et al., 1990); Austria (Mandl et al., 2010); Hungary (Guérin-Franiatte, 1966); Italy (Venturi and Nannarone, 2002). North America: British Columbia (Pálfy et al., 1994), Nevada (Smith, 1981); Mexico (Meister et al., 2002). South America: Chile (Quinzio-Sinn, 1987); Colombia (Geyer, 1976).   Localities: F1-11, F1-27, F1-20, F3-05; L2-07, T 11, T 13.  130     Fig. 6-10 Shell size (D), whorl height (WH), whorl expansion rate (EXP) plotted against umbilical diameter (UD) of Arnioceras miserabile, compared with that of (Guérin-Franiatte, 1966, neotype refigured therein).    Arnioceras n. sp. A Page 193, Plate 11, Figs. 5-6. 0.010.020.030.040.050.00.0 5.0 10.0 15.0 20.0 25.0DGuérin-Franiatte, 1966NeotypeFCDLC0.03.06.09.012.015.00.0 5.0 10.0 15.0 20.0 25.0WH0.501.001.502.002.503.000.0 5.0 10.0 15.0 20.0 25.0WexpUD131   Materials: 2 specimens from Last Creek preserved in concretions in calcareous shale.  Measurements:  Specimen # D UD U WW WH PRHW EXP T 11-03 41.4 17.9 0.43  12.2 21 2.06 T 11-04 45.2 18.2 0.40  15.1 23 1.98  Description:  Medium sized, evolute forms. Whorl shape is subrectangular to elliptic (Fig. 6-11). Flanks are rather flat to slightly convex. Umbilical wall is fairly high, inclined or vertical. Umbilicus is narrow for the genus (U≈0.40). Nucleus is smooth up to 15~20 mm, but has weak striae, which is a distinct character of this species. The early ribs are slightly flexuous, then become straight. The ribs are sharp, dense and rursiradiate, gently project forward onto the venter. Rib frequency increases with growth. The venter is convex, tricarinate-bisulcate. The median keel is more prominent than lateral keels. The whorl expansion rate is fairly high (EXP≈2.0).   Discussion:  This species is readily distinguishable from most other species of Arnioceras by its large smooth nucleus, high whorl expansion rate and narrow umbilicus. The holotype of A. semicostatum (Guérin-Franiatte, 1966, pl. 137, figs. 1a-1b,) also has a large smooth nucleus, but it’s more evolute, and both the whorl expansion rate and the rib frequency are lower. Small specimens (D<20 mm) of A. miserabile and A. laevissimum can be difficult to be distinguished from the juvenile forms or the nucleus of Arnioceras. n. sp. A when preservation is limited. The slight differences are, both A. miserabile and A. laevissimum have lower whorl expansion rate, lower umbilical wall and no ornamentation at all or weaker striae.  132   Occurrence and Distribution:  The specimens were collected from the headwaters of Last Creek in association with A. miserabile and other species of Arnioceras, Leslei Zone. This species is currently known from British Columbia.   Localities: T 11.     Fig. 6-11 Whorl section of Arnioceras n. sp. A. Specimen T 11-04.  133  Family ARIETITIDAE Hyatt, 1875  Subfamily ASTEROCERATINAE Spath, 1946 Genus CAENISITES Buckman, 1925   Type species: Caenisites caenus Buckman, 1925, monotype.   Synonymy: Euasteroceras DONOVAN, 1953 (type species Ammonites turneri SOWERBY, 1824; by original designation).   Description:  Moderately involute forms. Whorl section subquadrate to subrectangular, could be subtrapezoidal at large sizes. Flanks flat or convex. The umbilicus is 30% to 50% of diameter. Umbilical wall high and steep. Venter bisulcate. Ribs straight to slightly concave, mostly prorsiradiate, and curve forward onto the ventrolateral shoulder. Rib strength decreases towards the venter, and may get smooth at large sizes. Rib frequency slowly increases with growth.   Remarks:  As suggested by Corna and Dommergues (1995), the main common character of Caenisites is the strong prorsiradiate ribbing that bend forward towards the ventrolateral shoulder. Some species of the genus may display different characters that make it difficult to provide a comprehensive generic description (Macchioni et al., 2006). For example, C. pulchellus (Guérin-Franiatte, 1966) has a higher rib frequency, and slightly biconcave ribs while C. plotti (Reynès, 1879) and C. aff. turneri (Macchioni et al., 2006) have tubercles on early whorls. Meister and Schlögl (2013) recently described several species of “Caenisites”, which is a morphologically intermediate between Coroniceras and 134  Caenisites, and might suggest the phylogenetic relationship between the two genera. Therefore, the status of several species of Caenisites remains to be clarified, as noted by Corna and Dommergues (1995) and Macchioni et al. (2006).   Age and Distribution:  Caenisites is the most characteristic taxon for the Turneri Zone in Europe. It is known from the upper part of the Leslei Zone in North America. Records of this genus include the following areas:  Europe: UK, France (Guérin-Franiatte, 1966); Switzerland (Dommergues et al., 1990); Italy (Fucini, 1903); Romania (Tibuleac, 2005); ?Slovakia (Meister and Schlögl, 2013). North America: British Columbia (Macchioni et al., 2006), ?Mexico (Taylor et al., 2001). South America: ?Chile (von Hillebrandt, 2002).    Caenisities brooki (SOWERBY, 1818)  Page 195, Plate 12, Fig. 1.     * 1818 Ammonites brooki SOWERBY, p. 203, pl. 190.  1903 Asteroceras brooki SOWERBY – FUCINI, p. 127, pl. 19, figs. 1a-c, non fig. 2a-c.   1961 Caenisites brooki SOWERBY – DEAN et al., pl. 66, fig. 1 (refigured holotype).  1966 Caenisites cf. brooki SOWERBY – GUÉRIN-FRANIATTE, p. 325, pl. 210 (refigured holotype), pl. 211-213, text-figs. 177-178.   1976 Asteroceras (Asteroceras) brooki SOWERBY – SCHLEGELMILCH, pl. 19, fig. 1 (refigured holotype).   1995 Caenisites brooki SOWERBY – CORNA and DOMMERGUES, p. 38, pl. 4, fig. 4, text-fig. 7.   2001 Caenisites n. sp. aff. brooki SOWERBY – TAYLOR, GUEX and 135  RAKÙS, pl. 3, figs. 5, 7, 9; pl. 4, figs. 5-6.   2006 Caenisites brooki SOWERBY – MACCHIONI et al., pl. 4, figs. 5-6; pl. 5, figs. 5-6; pl. 8, figs. 1,4, 10-11; text-fig, 3F.  Materials: 1 specimen found ex situ from Last Creek preserved in a concretion in sandstone.   Measurements:  Specimen # D UD U WW WH WWWH PRHW T 15 174.0 56.0 0.32  73.6  17  Description:  Fairly large, quickly expanding and moderately involute form. Whorl height larger than width. Whorl section subrectangular to subtrapezoidal. Flank is fairly flat. Umbilicus is about one third of diameter. Umbilical wall is high and vertical. Umbilical shoulder is rounded. Venter is flat, bisulcate-tricarinate. The median keel is slightly higher than lateral ones. The lateral keels are blunt and rounded. Ribs are strong and gently prorsiradiate, and curve gently forward on the upper flank. Ribs strength decrease towards the venter, and might be smooth on the upper flank of the outer whorl. Ribs frequency slowly increases with growth.  Discussion:  Caenisites brooki is most similar with Caenisites turneri, but is more involute and has higher whorl overlap and relatively more compressed whorl section. Macchioni et al. (2006) suggest both species may represent two morphological extremes of the same taxon. C. brooki differs from C. pulchellus by its stronger ribs and dense ribs. It also differs from Caenisites cf. turneri in this work also by its higher umbilical wall, and stronger forward curving. It differs from Caenisites sp. by its more compressed whorl section, and less blunt keel.  136   Occurrence and Distribution:  The specimen was collected ex situ from the headwaters of Last Creek, probably from the upper part of the Leslei Zone. Caenisites brooki is one of the characteristic taxa of the Turneri Zone in Europe. It has been reported from the following areas:  Europe: UK (Howarth, 2002), France (Corna and Dommergues, 1995); Austria (Mandl et al., 2010), Italy (Fucini, 1903), Romania (Tibuleac, 2005). North America: British Columbia (Macchioni et al., 2006); Mexico (Taylor et al., 2001).   Locality: T 15.    Caenisities turneri (SOWERBY, 1824) Page 193, Plate 11, Fig. 7.    * 1824 Ammonites turneri SOWERBY, p. 75, pl. 452, fig. 1.   1903 Asteroceras turneri SOWERBY – FUCINI, p. 126, pl. 19, figs. 3a-c, 4a-c.   1903 Asteroceras brooki SOWERBY – FUCINI, p. 127, pl. 19, figs. 2a-c, text-fig. 76.   1961 Caenisites turneri SOWERBY – DEAN, DONOVAN and HOWARTH, pl. 66, figs. 2a-b.  1966 Caenisites turneri SOWERBY – GUÉRIN-FRANIATTE, p. 321, pl. 204, 205, figs. 1-2, pl. 206-207, text-figs. 174-175. cf. 1995 Caenisites aff. turneri SOWERBY – CORNA and DOMMERGUES, p. 38, pl. 4, fig. 3, text-fig. 7.   2002 Caenisites turneri SOWERBY – HOWARTH, p. 124, pl. 2, figs. 3, 5.  2006 Caenisites turneri SOWERBY – MACCHIONI et al., pl. 3, figs. 1, 4; pl. 4, figs. 1-4, 7, 8; pl. 5, figs. 2, 4; pl. 7, figs, 1-2; pl. 8, figs. 2, 8; text-fig. 137  3B-J.   Materials: 1 specimen from Last Creek preserved in calcareous shale.   Measurements:  Specimen # D UD U WW WH WWWH PRHW L2-03 ~97.0 38.8 0.40 32.7 35.2 0.93 ~18  Description:  Medium sized, moderately involute forms. Whorl section subtrapezoidal to subquadrate. Flanks slightly convex. Umbilical wall is fairly high and steep, umbilical shoulder rounded. Venter is bisulcate-tricarinate, with a strong but fairly blunt median keel. Ribs are strong, prorsiradiate, and bend forward onto the ventrolateral shoulder. The ribs tend to become slightly concave with growth.   Discussion:  Guérin-Franiatte (1966) discussed the differences between Caenisites turneri and C.  subturneri, noting that C. subturneri has a broader venter with shallower sulci, and thicker and stronger ribs. The differences of C. turneri and C. brooki are discussed under C. brooki.   Occurrence and Distribution:  This specimen was collected from the upper part of the Leslei Zone in the headwaters of Last Creek. C. turneri is the name bearer of the Turneri Zone in Europe. It has been reported form the following areas:  Europe: UK, France (Guérin-Franiatte, 1966); Italy (Fucini, 1903). North America: British Columbia (Macchioni et al., 2006).   138  Locality: L2-03.     Caenisites sp.  Page 193, Plate 11, Fig. 8.  Materials: 2 fragments from Last Creek preserved in calcareous shale.   Measurements:  Specimen # D UD U WW WH WWWH PRHW L2-02-01    60.5 54.2 1.11  L2-02-02    54.2 59.0 0.92   Description:  Each of the two specimens is a part of a fairly large phragmocone. The whorl sections are elliptical to subquadrate (Fig 6-12). Flanks are convex and rounded. The venter is bisulcate-tricarinate. Ventrolateral shoulder is rounded. The keels are blunt. The median keel is stronger and more prominent than lateral ones. Ribs are strong, rectiradiate to slightly prorsiradiate, showing intermediate rib frequency.      Fig. 6-12 Whorl section of Caenisites sp. Specimens: a. L2-02-01; b. L2-02-02. 139   Discussion:  The specimens resemble Caenisites, and are tentatively compared Caenisites turneri based on their ventral characters and relatively high WWWH ratio. However, the limitation of preservation doesn’t allow more comparison. It differs from C. brooki by its less compressed whorl section. C. pulchellus can have similar whorl section, but it has a higher rib frequency.   Occurrence and Distribution:  The specimens were collected from the upper part of the Leslei Zone in the headwaters of Last Creek, in association with Caenisites and Arnioceras. Currently, it has been reported from British Columbia.   Locality: L2-02.  140  Genus ASTEROCERAS HYATT, 1867   Type species: Ammonites stellaris SOWERBY, 1815. Subsequent designation by Buckman, 1911.    Description:  Moderately involute with a fairly high whorl expansion rate, and may reach very large sizes. Whorl section subtrapezoidal to subrectangular. Upper flanks converge towards the venter. Umbilical wall high and commonly rounded. The venter bears a blunt median keel shouldered with wide sulci and lateral keels, which may die out on outer whorls at large diameters. Ribs are strong, simple, prorsiradiate, may swing forward onto the venter or become smooth on the ventrolateral shoulder.   Remarks:  Guérin-Franiatte (1966) provided a comprehensive treatment of Asteroceras, listing 16 species. Schlegelmilch (1976) treated Asteroceras with a broader genus definition that included Asteroceras s. str., Caenisites, Euasteroceras, Eparietites and Agasteroceras. However, most current workers prefer to treat these as separate genera (e.g., Howarth, 2013).   Age and Distribution:  Asteroceras is a cosmopolitan taxon occurring from the Carinatum Zone in North America, which is equivalent to the Obtusum Zone in Europe, but it has representatives in the preceeding Turneri Zone (Pálfy, 1991). There are numerous reports from the following areas:  Europe: UK, France (Guérin-Franiatte, 1966), Germany, Austria (Mandl et al., 2010), Switzerland (Reisdorf et al., 2011), Luxembourg (Maubeuge, 1998), Italy (Cecca et 141  al., 1987), Hungary (Géczy and Meister, 2007), Turkey (Alkaya and Meister, 1995), ?Spain (Braga et al., 1984), Romania (Tibuleac, 2005), Slovakia (Meister and Schlögl, 2013). North America: Alaska (Imlay, 1981), British Columbia (Pálfy et al., 1994), Alberta (Hall, 1987), ?California (Sanbord, 1960), Nevada (Smith, 1981), Mexico (Taylor et al., 2001). South America: Chile (von Hillebrandt, 2002), Peru (Erben and Haas, 1985). Asia: Guangdong (Wang and Smith, 1986), Vietnam (Sato, 1992), ?Papua New Guinea (Sukamto and Westermann, 1992). Africa: Morocco (e.g., Wilmsen et al., 2002).    Asteroceras cf. varians FUCINI, 1903 Page 197, Plate 13, Figs. 1-2    *cf. 1903 Asteroceras varians FUCINI, pl. 31, figs. 1-5.   1991 Asteroceras cf. varians FUCINI – PÁLFY (cum synonymy), pl. 10, figs. 4, 6.  cf. 1994 Asteroceras varians FUCINI – DOMMERGUES, FERRETTI & MEISTER, p. 24, pl. 2, fig. 18.  1994 Asteroceras cf. varians FUCINI – PÁLFY, SMITH & TIPPER, pl. 1, fig. 7. cf. 1996 Asteroceras varians aff. interposita FUCINI – EL HARRIRI et al., pl. 67, figs. 16-18.   1997 Asteroceras varians FUCINI – JOHANNSON et al., 1997, p. 1034, pl. 1, fig. 4.  ? 1998 Asteroceras gr. varians aff. interposita FUCINI – LACHKAR et al., p. 599.  cf. 2007 Asteroceras varians FUCINI – GÉCZY and MEISTER, pl. 20, figs. 1-2. ? 2007 Asteroceras varians var. interposita FUCINI – GÉCZY and MEISTER, pl. 21, fig. 2.  142  cf. 2010 Asteroceras gr. varians FUCINI – EL HARRIRI, DOMMERGUES & CHAFIKI, p. 233, pl. 1, figs. 1-2, 5-6; pl. 2, figs. 1-2, 5-8.  Materials: 6 flattened internal molds from Five Card Draw preserved in shale, 1 external mold from the entrance of New York Canyon preserved in limestone.   Measurements:  Specimen # D UD U WW WH WWWH PRHW F2-14-01 50.3 16.6 0.33  21.4  13  Description:  Medium sized, moderately involute forms. The specimens are mostly flattened fragments, but still show convex flanks. Whorl section and ventral view not available. The umbilicus is about one third of diameter. Ribs strong, slightly sinuous, rectiradiate to gently prorsiradiate. Rib strength decreases at the upper flank and the ribs gradually fade away towards the venter. Rib frequency is fairly low.   Discussion:  Asteroceras varians Fucini, 1903 is characterized by its quite compressed whorl section, commonly fading of the ribs towards the venter, fairly closed umbilicus, and a non-sulcate ventral keel or a very blunt keel. It is also known for its variability of the ribbing pattern and ventral characters (e.g., Géczy and Meister, 2007; El-Harriri et al., 2010). The specimens of this study are in good agreement with A. cf. varians in Pálfy (1991), especially their slightly sinuous ribbing pattern, despite the limited preservation. Therefore, they are tentatively assigned to the varians group. Asteroceras cf. varians differs from A. cf. margarita by its sinuous ribs, a lower rib frequency and being more involute. Asteroceras sp. differs from A. cf. varians by its straighter and blunt ribs.   143  Occurrence and Distribution:  The specimens were collected from the Carinatum Zone in Five Card Draw and the entrance of New York Canyon. Asteroceras cf. varians is a characteristic taxon of the Carinatum Zone in North America. However, Taylor et al. (2001) recorded a questionable species Asteroceras aff. varians that ranges within the preceding Leslei Zone. Asteroceras varians is also a characteristic taxon of the Obtusum Zone in Europe, particularly the Stellare Subzone (Géczy and Meister, 2007). The Asteroceras varians group has been reported from the following areas:  Europe: Austria, Hungary, Switzerland, Italy, Turkey (e.g., El-Harriri et al., 2010). North America: Alaska (Imlay, 1981), British Columbia (Pálfy et al., 1994), Nevada. Elsewhere: Morocco (El Harriri et al., 2010).   Localities: F2-14, F2-16.    Asteroceras cf. margarita (PARONA, 1896) Page 197, Plate 13, Fig. 5.    *cf. 1896 Arietites margarita PARONA, pl. 5, figs. 8a-b. cf. 1903 Asteroceras margarita PARONA – FUCINI, pl. 32, figs. 4-5. cf. 1966 Asteroceras margarita PARONA – GUÉRIN-FRANIATTE, p. 228, text-fig. 148; pl. 159 (refigured holotype); pl. 159; pl. 160; pl. 161, fig. 1.  ? 1966 Asteroceras aff. margarita PARONA – GUÉRIN-FRANIATTE, pl. 161, fig. 2; pl. 162.  cf. 1991 Asteroceras aff. margarita PARONA – PÁLFY, p.140, pl. 10, fig. 6. cf. 1994 Asteroceras aff. margarita sensu FUCINI non PARONA – DOMMERGUES et al., p. 27, pl. 2, fig. 19.   144  ? 2010 Asteroceras aff. margarita PARONA sensu FUCINI – EL HARRIRI et al., p. 235, pl. 2, figs. 3-4.  Materials: 3 flattened internal molds from Five Card Draw preserved in shale, and 1 three-dimension internal mold collected ex situ from Last Creek preserved in a concretion in shale.   Measurements:  Specimen # D UD U WW WH WWWH PRHW L-12-I5-1 ~175.0 ~79.0 0.41 ~52.0 ~63.0 0.83 ~18  Description:  Small to medium sized, moderately involute to moderately evolute forms. Whorl section and ventral view not available on Five Card Draw specimens. The specimen from Last Creek has a slightly compressed subtrapezoidal whorl section. The ventral area is fairly wide, tricarinate-bisulcate. The median keel blunt and shouldered with wide and shallow sulci. For all specimens, the flanks are rather flat to weakly convex at diameters smaller than 10cm, but more convex at larger sizes. The umbilical wall is high and rounded. The ribs are straight, prorsiradiate, and fairly sharp and dense for the genus. The ribs of the Last Creek specimen bear weak tubercles in the inner whorl and curve forward very slightly onto the ventrolateral shoulder.   Discussion:  The specimens resemble Asteroceras margarita (Guérin-Franiatte, 1966) except in being more evolute. The interpretation of Asteroceras margarita still remains ambiguous due to the preservation and variability, especially in the ribbing pattern and rib strength, resulting in a number of affinities (see synonymy list). The most comprehensive summary of this species is given by El Harriri et al. (2010). Asteroceras cf. margarita differs from A. 145  stellare by its relatively sharper ribs and higher rib frequency. The difference of Asteroceras cf. margarita and A. cf. varians is discussed under A. cf. varians. It differs from Asteroceras sp. by its higher rib frequency, and no strong fading or smoothing of the ribs towards the venter. Coroniceras mutabile is the closest form which has tuberculation, but it has a quite different ribbing pattern, a narrower venter, and is stratigraphically lower. Thus, the tubercles in specimen L-12-I5-1 is considered as an intra-species variation.   Occurrence and Distribution:  Specimen L-12-I5-1 was collected ex situ from the headwaters of Last Creek, probably from the Carinatum Zone. All the other specimens were collected both in situ and ex situ from the Carinatum Zone in Five Card Draw. Asteroceras margarita is a characteristic taxon of the Obtusum Zone in Europe, probably the Stellare Subzone. The margarita group has been reported from the following areas:  Europe and northern Africa: France, Austria, Italy, Morocco, Algeria (El-Harriri et al., 2010). North America: British Columbia (Pálfy, 1991), Nevada.   Localities: F2-14, L-12-I5.    Asteroceras sp. Page 197, Plate 13, Figs. 3-4.   Materials: 3 flattened internal molds and 1 external mold from Five Card Draw preserved in shale, all of them whorl fragments.   Description:  The whorl height of the specimens vary from 3 cm to 5 cm, indicating the diameters 146  about 10 to 15 cm. Moderately involute. Whorl section and ventral view not available. Flanks are slightly convex, and umbilical wall is fairly high and rounded. The ribs are strong, straight, rectiradiate to slightly prorsiradiate. Rib frequency moderate for the genus, PHRW presumably lower than 15. The ribs tend to become smooth on the ventrolateral shoulder, no forward projection or curving.   Discussion:  The ribbing pattern resembles Asteroceras but placement at the species level require more complete materials. It is tentatively compared to A. stellare and A. suevicum (Guérin-Franiatte, 1966) with limitation, both of which could have strong, straight ribs that fade in strength towards the venter, and similar rib frequency. The difference with A. cf. varians and A. cf. margarita is discussed under A. cf. varians and A. cf. margarita respectively.   Occurrence and Distribution:  The specimens were collected from the Carinatum Zone in Five Card Draw, Nevada.   Localities: F1-27.   147  Genus EPARIETITES Spath, 1924   Type species: Arietites tenellus SIMPSON, 1855, figured in BUCKMAN (1912).  Description:  Involute forms with compressed shell. Umbilicus narrow, ventral keel sharp and high. Ribs simple, straight or concave, gently swing forward onto the venter, sometimes can be irregular. The ribs might be lost and the whorl becomes smooth at large sizes (Arkell et al., 1957; Howarth, 2013).   Remarks:  It is in general agreement to treat Eparietites as a separate genus (e.g., Arkell et al., 1957; Guérin-Franiatte, 1966; Howarth, 2013) instead of a subgenus of Asteroceras (Schlegelmilch, 1976; Smith, 1981). Donovan (1987) suggested that Eparietites is the phylogenetic transition between Asteroceras and Oxynoticeras.   Age and Distribution:  Eparietites occurs at the upper part of the Carinatum Zone in North America. It is characteristic of the Upper Obtusum Zone in Europe, and is known from the following areas:  Europe: UK and France (Guérin-Franiatte, 1966 and thererin); Austria (Dommergues et al., 1995); Switzerland (Dommergues et al., 1990); Sweden (Reyment, 1959); Romania (Tibuleac, 2005); Northeast Russia (Sey et al., 1992). North America: Nevada (Smith, 1981); Mexico (Erben, 1956). South America: ?Peru (Geyer, 1979); Chile (von Hillebrandt, 2002). Asia: Guangdong (Wang and Smith, 1986).   Eparietites ex gr. impedens (YOUNG & BIRD, 1928) 148  Page 199, Plate 14, Fig. 1.    *gr. 1828 Ammonites impedens YOUNG & BIRD, p. 266, figured by BUCKMAN, (1919, pl. 120).  2002 Eparietites ex gr. E. flowleri (BUCKMAN, 1884) – HILLEBRANDT, p. 73, pl. 6, fig. 4. gr. 2005 Eparietites impedens YOUNG & BIRD – DOMMERGUES et al. (cum synonymy), p. 680-681, pl. 1, figs. 10-13; pl. 2, figs. 1-2.  Materials: 1 external mold from Five Card Draw preserved in shale (F-13-UJ3-1), ex situ.   Description:  Medium sized, involute form. Whorl section and ventral view not available. Flank rather flat. The umbilicus is narrow. Ribs are strong, rectiradiate to weakly rursiradiate, slightly sinuous, and gradually widen and become smooth towards the venter.   Discussion:  Dommergues et al. (2005) synonymized Eparietites fowleri under E. impedens and treated the morphological disparity as intraspecific variability. The preservation of this specimen is limited and cannot contribute to the taxonomic placement, but the sinuous pattern of the ribs is in good agreement with the Eparietites ex gr. E. fowleri (von Hillebrandt, 2002). It differs from Asteroceras cf. varians in this work by being more involute, and more densely ribbed.   Occurrence and Distribution:  The specimen was collected ex situ from the Carinatum Zone in Five Card Draw.  Eparietites impedens is characteristic for the Obtusum Zone in Europe, particularly the Denotatus Subzone. The E. impedens group has been reported from the following areas:  149  Europe: UK and France (Guérin-Franiatte, 1966). North America: Nevada. South America: Chile (von Hillebrandt, 2002); Peru (Prinz, 1985).   Locality: F-13-UJ3.  150  Genus EPOPHIOCERAS Spath, 1924  Type species: Ammonites landrioti D'ORBIGNY, 1850 (nomen dubium). Type specimen figured by Reynès (1879), clarified by Thevenin (1907) and refigured by Guerin-Franiatte (1966). Original designation by Spath (1924).   Description:  Medium to large sized, evolute forms. Whorl section subcircular with a slight overlap between the whorls. Umbilicus around 60% of diameter, or higher at larger sizes. Flanks commonly convex. Ventral keel weak, ventrolateral shoulder rounded, no or very shallow sulci. Ribs quite blunt, sometimes interrupted. Rib frequency increases with growth. A more comprehensive treatment is given by (Guérin-Franiatte, 1966).   Remarks:  Epophioceras is tentatively placed in Asteroceratidae since the classification is still an on-going discussion. Traditionally, it is placed in Asteroceratidae, e.g., Guérin-Franiatte (1966) who gave a comprehensive treatment of this genus, and considered it to be derived from Asteroceras (Donovan, 1987). Schlatter (1984) and Hillebrandt (2002) suggested a closer affinity of Epophioceras with Echioceratidae. More recent workers (e.g., Dommergues, 1993; Dommergues et al., 1994; Géczy and Meister, 2007) prefer to follow the traditional classification but also admit the dispute, pending more detailed taxonomic investigation.  The homeomorphy between the Arietitidae and the Echioceratidae involves Vermiceras (including Metophioceras), Epophioceras and Paltechioceras (Donovan, 1987; Hall, 1987; Riccardi et al., 1991). The sutures can be used to distinguish them when available, and is discussed in detail in Getty (1973) and Schlatter (1984). The fact that there is no overlap among the three genera can also help with identification, especially between 151  Epophioceras (in association with Asteroceras and Arnioceras) and Paltechioceras (above Epophioceras, Asteroceras and Arnioceras).    Age and Distribution:  Epophioceras is a characteristic taxon of the Obtusum Zone in Europe and is the rootstock of Echioceratidae (e.g., Guex et al., 2008). It is the most common taxon of the Carinatum Zone in North America. Epophioceras has a wide distribution from the following areas:  Europe: UK, France, Germany and Austria (Mandl et al., 2010); Hungary (Géczy and Meister, 2007); Italy (Fucini, 1902). North America: British Columbia (e.g., Johannson et al., 1997); Alberta (e.g., Asgar-Deen et al., 2003); Nevada (e.g., Taylor et al., 2001). South America: Peru (Prinz, 1985); Chile (von Hillebrandt, 1973); Argentina (Riccardi et al., 1991). Elsewhere: possibly Antarctica (Thomson and Tranter, 1986).    Epophioceras carinatum SPATH, 1924  Page 199, Plate 14, Figs. 4, 6, 7.     1867 Ammonite landrioti D’ORBIGNY – DUMORTIER, p.128, pl. 23, figs. 1, 2.  * 1924 Epophioceras carinatum SPATH, p. 204.  ? 1956 Arnioceras ? mogeslopezi ERBEN, p. 274, pl. 31, figs. 5, 6 (nomen correctum).   1966 Epophioceras carinatum SPATH – GUÉRIN-FRANIATTE, p. 333, pl. 222, 223.   1979 Epophioceras sp. ex gr. carinatum SPATH – GEYER, p. 209, fig. 5e.   1981 Epophioceras cf. carinatum SPATH – SMITH, pl. 2, figs. 7, 9; pl. 3, figs. 1, 3; text-fig. 6-4.  152  ? 1985 Epophioceras cf. carinatum SPATH – ERBEN & HAAS, p. 179, pl. 4, fig. 1.  cf. 1991 Epophioceras aff. carinatum SPATH – PÁLFY, p. 146, pl. 10, figs. 3, 7, 8.   2001 Epophioceras carinatum SPATH – TAYLOR, GUEX & RAKÚS, p. 418, pl. 7, figs. 1-2; p. 420, pl. 8, fig. 4.   Materials: 6 in situ and 4 ex situ specimens from Five Card Draw preserved in shale, all flattened.   Measurements:  Specimen # D UD U WW WH WWWH PRHW F1-29-05 102.1 55.9 0.55  24.2  ~22 F1-28 63.4 37.6 0.59  18.3  20 F-13-MJ3-4 ~41.5 23.4 0.56  9.2  17 F-13-UJ3-3 58.4 34.1 0.58  14.6  17  Description:  Medium to large, evolute forms. Umbilicus is nearly 60% of diameter. Whorl section not available. Flanks are convex and slightly rounded even on flattened specimens. The umbilical wall is very low. The venter bears a median keel no sulci or lateral keel. Ribs strong, gently prorsiradiate to strongly prorsiradiate, may be gently concave or decrease in strength on the ventrolateral shoulder. Rib frequency increases with growth.   Discussion:  The specimens in this work are in good agreement with Epophioceras carinatum, though with limited preservation of ventral characters. It differs from E. longicella (Guérin-Franiatte, 1966) by its lower rib frequency at comparable sizes and more prominent ventral keel. The difference with E. wendelli in this work is that E. wendelli has concave, rursiradiate ribs, and a higher rib frequency.   153   Occurrence and Distribution:  E. carinatum is the name bearer and most common taxon for the Carinatum Zone in North America, and has been recorded from the Obtusum Zone in Europe. It is a cosmopolitan taxon which has been reported from the following areas:  Europe: UK, France (Guérin-Franiatte, 1966); North America: British Columbia (Pálfy et al., 1994); Nevada (e.g., Taylor et al., 2001); ?Mexico (Erben, 1956); South America: Peru (Erben and Haas, 1985); Chile (von Hillebrandt, 1981).   Localities: F1-27, F1-28, F1-29, F2-03, F2-07, F2-12.    Epophioceras cf. carinatum SPATH, 1924 Page 199, Plate 14, Fig. 5.  Materials: 2 ex situ external molds and 2 in situ internal molds from Five Card Draw preserved in shales and limestone, flattened and fragmented.   Measurements:  Specimen # D UD U WW WH WWWH PRHW F-13-I1-1 74.2 48 0.65  13.9  19  Description:  Medium sized, quite evolute forms. Flanks slightly convex. Whorl section and ventral view are not available. The umbilical wall is low and flat. Ribs are concave, rectiradiate to slightly prorsiradiate, quite strong and sharp for the genus. Rib relief is high. Rib frequency is moderate to low for the genus at comparable sizes, and increases with growth.   154  Discussion:  As far as preservation allows, the specimens are closely related to E. carinatum by their volution and ribbing pattern, although their ribs are more concave and not so prorsiradiate as in E. carinatum. They differ from E. cognitum by a higher rib frequency and more concave ribs, and differ from E. hebetitus by a higher rib frequency and sharper ribs.   Occurrence and Distribution:  The specimens were collected from the Carinatum Zone in Five Card Draw, Sunrise Formation. For the distribution of E. carinatum group, see E. carinatum.   Localities: F2-11, F1-32.    Epophioceras cf. wendelli TAYLOR, GUEX & RAKÚS, 2001 Page 199, Plate 14, Figs. 2-3.    *cf. 2001 Epophioceras wendelli TAYLOR, GUEX & RAKÚS, p. 398, pl. 7, figs. 1-2 (holotype), figs. 4-5, 6-7.  Materials: 6 in situ and 1 ex situ specimens from Five Card Draw preserved in shales, mostly fragmented and flattened.   Measurements:  Specimen # D UD U WW WH WWWH PRHW F2-06-08  ~103.1   ~31.1  ~30 F2-19-04  ~108.2   ~26.0  ~31   155  Description:  Large, evolute forms. Estimated sizes can reach 15 cm in diameter or larger. Whorl section not available. Flanks are convex and slightly rounded even in flattened materials. Umbilical wall is low and quite flat. Ribs are concave, rectiradiate, and may fade away when reaching the venter. Ribs frequency quite high for the genus, and increases with growth. Ventral view not available. Lateral lobes are low, and saddles high. Both are highly incised (Fig. 6-13).   Discussion:  This species was erected by Taylor et al. (2001) based on its wide whorl section and dense ribbing, which are the principal differences from E. longicella. Two other species, E. cognitum and E. hebetius (Guérin-Franiatte, 1966), may have a similar concave ribbing pattern, but their rib density is much lower. The difference with E. carinatum is discussed in E. carinatum.   Occurrence and Distribution:  E. wendelli is a characteristic taxon of the Carinatum Zone in North America. It has been currently reported from Nevada and Mexico (Taylor et al., 2001).   Localities: F2-06, F2-07, F2-12, F2-19, F2-20.    Fig. 6-13 Septal suture of Epophioceras cf. wendelli, WH=26.5 mm. Specimen F2-19-04. 156    Epophioceras sp. Page 201, Plate 15, Figs. 1-3.   Materials: 2 in situ and 2 ex situ specimens from Five Card Draw preserved in shale, fragmented and flattened.   Measurements:  Specimen # D UD U WW WH WWWH PRHW F2-10 ~65.6 ~45.0 0.69  ~10.9  ~23 F2-13-01 ~59.7 ~35.7 0.60  ~12.7  ~20  Description:  Medium sized, very evolute, slowly expanding forms. The complete specimen can probably reach 9~10 cm. Umbilicus is about 60~70% of diameter. Flanks are quite flat. The umbilical wall is very low. The ribs are straight, quite sharp for the genus, rectiradiate. The ribs density is high for the genus, and increase with growth. The venter view is not available on these materials but a keel does exist.   Discussion:  The poorly preserved specimens are assigned into Epophioceras based on their volution, ribbing pattern, and stratigraphic position. The high rib frequency is comparable to E. landrioti (Guérin-Franiatte, 1966), but the ribs of our specimens are sharper and not prorsiradiate. Erben and Haas (1985) described a specimen Epophioceras sp., which shows a similar ribbing pattern and rib frequency, but the flanks are convex and the umbilical wall is fairly high for the genus, and it’s not comparable to our flattened materials. The character of straight, rectiradiate ribbing combined with high rib frequency separates them from E. 157  carinatum, E. cf. carinatum and E. cf. wendelli in this work.   Occurrence and Distribution:  The specimens were collected from the Carinatum Zone in Five Card Draw. It has currently been reported from Nevada.   Localities: F2-06, F2-10, F2-13.    158  Family ECHIOCERATIDAE Buckman, 1913  Very evolute, serpenticone with strong but simple ribs (except in Leptechioceras) which was split into a large number of species. A comprehensive revision on generic classification is given by Getty (1973). The relationship between Epophioceras and Echioceratidae is discussed under Epophioceras. The multivariate analysis approach proposed by Smith (1981) is not used here due to the small number of well-preserved specimens. The diagnose features of the genera largely refer to Schlatter (1991), Hillebrandt (2002), Guex et al. (2008), and Howarth (2013).   Genus PALTECHIOCERAS Buckman, 1924  Type species: Paltechioceras elicitum BUCKMAN, 1924, pl. 483, by original designation.   Synonymy: Echioceratoides, Epechioceras, Euechioceras, Kamptechioceras, Metechioceras, Plesechioceras, Vobstericeras, all erected by TRUEMAN & WILLIAMS, 1925; Stenechioceras by BUCKMAN, 1927; Melanhippites by CRICKMAY, 1928.   Description:  Evolute forms, can reach large sizes. Whorl section compressed. Flanks flat or slightly convex. Venter is tricariante-bisulcate, the median keel fairly prominent. Ribs are dense, straight or nearly straight, may be locally interrupted or looped in some species. Rib frequency increase steadily with growth. Homeomorphic with Vermiceras (Howarth, 2013).   Remarks:  Plesechioceras was synonymized into Paltechioceras by Getty (1973) and Donovan et al. (1981). Dommergues (1982) justified Plesechioceras by its ribbing pattern, 159  weak keel and absence of tricarination, which is the case for the type specimens but contradictory to some more recently illustrated specimens (e.g., Blau et al., 2003; Géczy and Meister, 2007) that are clearly tricarinate. Some other workers (e.g., Guex et al., 2008) suggest to treat Plesechioceras as a subgenus of Paltechioceras. In this work we favor the practice of Getty (1973) and Donovan et al. (1981).  Paltechioceras is the first echioceratid in North America whereas Palaeoechioceras is the first in Northwest Europe (Smith, 1981) and the Mediterranean. Guex et al. (2008) compared the evolutionary schemes proposed by different workers (Getty, 1973; Dommergues, 1982; Donovan, 1987), all of whom suggest Epophioceras as the arietitid root stock of the echioceratids and with Palaeoechioceras derived from Epophioceras. The contrast between North America and Northwest Europe and the Mediterranean suggests that reconsideration of this evolutionary scheme is in order with Paltechioceras playing a more central role in the radiation of the echioceratids.   Age and Distribution:  Paltechioceras is a characteristic taxon in the Raricostatum Zone in Europe. In North America, it is the earliest echioceratid, and spans most the Harbledownense Zone. It has a cosmopolitan distribution from the following areas:  Europe: UK (e.g., Edmunds et al., 2003), France (e.g., Meister et al., 2012), Austria (e.g., Blau, 1998); Switzerland (e.g., Dommergues et al., 1990); Italy (e.g., Dommergues et al., 1994); possibly Geogia (Topchishvili, 1998); Slovakia (e.g., Meister et al., 2011); Romania (e.g., Tibuleac, 2005). Northern Africa: Morocco (e.g., El-Harriri et al., 2010); Tunisia (e.g., Rakús and Guex, 2002); Algeria (e.g., Dommergues et al., 2008). North America: ?Alaska (Imlay, 1981); ?Yukon (Poulton, 1991), British Columbia (Pálfy et al., 1994); Nevada (e.g., Taylor et al., 2001); Mexico (e.g., Islas et al., 2009). South America: Peru (e.g., Erben and Haas, 1985); Chile and Argentina (e.g., Hillebrandt, 2002); Ecuador (e.g., Dommergues et al., 2004). Elsewhere: China (Sun et al., 1980).  160    Paltechioceras cf. harbledownense (CRICKMAY, 1928) Page 201, Plate 15, Figs. 4-6.    *cf. 1928 Melanhippites harbledownense CRICKMAY, p. 61, pl. 3, pl. 4, figs. a-d. cf. 2003 Paltechioceras ? harbledownense CRICKMAY – BLAU et al. (cum synonymy), p. 427, pl. 5, figs. 1, 4, 5.  cf. 2004 Paltechioceras ? harbledownense CRICKMAY – DOMMERGUES et al., p. 363, pl. 1, figs. 3, 4.   Materials: 13 specimens from Five Card Draw 3 specimens from New York Canyon preserved in shale and limestone. The specimens are mostly flattened and fragmented.   Measurements:  Specimen # D UD U WW WH WWWH PRHW F2-21-01 ~51.2 29.8 0.58  13.7  34 F1-35-01 36.1 18.3 0.51  8.8  28 F2-24-01 ~41.6 25.4 0.61  11.3  ~29 F1-38-02 ~89.9 51.8 0.58  18.2  ~32  Description:  Medium to large sized, very evolute forms. Umbilicus is mostly 55-65% of diameter. Flanks convex, umbilical wall low. Venter view is not available, but a laterally sulcate keel is visible on flattened specimens. Ribs very dense, prorsiradiate, can be slightly concave. Ribs strength may decrease on ventrolateral shoulder. Rib density increase with growth.   Discussion:  This species was the type species of the genus Melanhippites (Crickmay, 1928), but was regarded as a nomen dubium by Getty (1973). Comprehensive discussions of the 161  species are given by Smith (1981), Pálfy (1991) and Blau et al. (2003). The specimens in this work resemble Paltechioceras harbledownense except that there is no ventral view.  The species be compared to P. mineralensis (Taylor et al., 2001) which is overall smaller in size, and the outer whorl tend to become smooth with growth. However, they can be difficult to differentiate at small sizes, and the preservation of the type specimen of P. mineralensis is very limited, so it can be potentially synonymized into P. harbledownense. The species can also be compared to P. flexicostatum which is more evolute and strongly tricarinate.   Occurrence and distribution:  P. harbledownense is the name bearer of the Harbledownense Zone in North America and one of the most abundant taxa. The specimens were collected from near the top of the Five Card Draw Member to the overlying New York Canyon Member in Five Card Draw, Harbledownense Zone. It is the earliest echioceratid in North America, while in Europe the earliest echioceratid is Palaeoechioceras (Smith, 1981). It has been reported from the following areas:  North America: British Columbia (e.g., Pálfy et al., 1994), Nevada (e.g., Taylor et al., 2001); ? Mexico (Blau et al., 2003). South America: ? Ecuador (Dommergues et al., 2004).   Localities: F1-35, F1-38, F2-20, F2-24.    Paltechioceras boehmi (HUG, 1899) Page 201, Plate 15, Figs. 7-8.    * 1899  Arietites boehmi HUG, p. 16, pl. 12, fig. 8. 162   1981 Paltechioceras boehmi HUG – SMITH, p. 176, pl. 4, figs, 1-2. cf. 1985 Paltechioceras cf. rothpletzi BÖSE – PRINZ, p. 180, pl. 4, fig. 3.  1998 Paltechioceras boehmi HUG – BLAU (cum synonymy), p. 208, pl. 4, figs, 9-20; pl. 5, fig. 21. ? 2005 Paltechioceras boehmi HUG – TIBULEAC, pl. 3, fig. 9.  aff. 2007 Paltechioceras aff. boehmi HUG – GÉCZY & MEISTER (cum synonymy), p. 186, pl. 29, figs, 7, 9.   2008 Paltechioceras boehmi HUG – GUEX et al., p. 90, pl. 17, fig. 3; pl. 12, fig. 8.  Materials: 11 ex situ specimens from Five Card Draw preserved in limestone.   Measurements:  Specimen # D UD U WW WH WWWH PRHW F2-24-02 ~79.7 53.5 0.67  ~16.3  ~29 F2-24-03 ~63.2 ~37.8 0.60 10.5 14.4 0.73 ~28 F2-24-04    10.3 16.3 0.63   Description:  Medium sized, very evolute forms. Umbilicus around 60% of diameter. Whorl section subelliptical. Flanks quite flat. Umbilical wall is low. Venter is arched, convex and bisulcate-tricarinate. The sulci are shallow and lateral keel is very weak. Ribs are dense, quite straight, and prorsiradiate, and tend to face on the ventrolateral shoulder. Rib density is slightly higher in the inner whorls than that in the outer whorl.   Discussion:  Dommergues and Meister (1989) and Géczy and Meister (2007) suggested to combine P. boehmi and P. favrei due to the similarity of the two species and their high disparity of the rib frequency, which is a practical approach for this work. P. favrei is included in the synonymy list in Géczy and Meister (2007).  163  This species differs from P. cf. harbledownense by its lower rib frequency, and not strongly prorsiradiate ribs. P. tardecrescens, which is stratigraphically higher, is a similar species but its rib frequency is more stable, and its whorl section is not as compressed as P. boehmi. A comprehensive discussion is given by (Blau, 1998).   Occurrence and Distribution:  P. boehmi is a cosmopolitan taxon in the Raricostatum Zone in Europe. The specimens in this work were collected ex situ from basal Harbledownense Zone in Five Card Draw. It occurs from the middle to upper part of the Harbledownense Zone (Taylor et al., 2001) in North America. This species has been reported from the following areas:  Europe: UK (e.g., Edmunds et al., 2003), France (e.g., Dommergues and Meister, 1989), Austria (e.g., Blau, 1998), Switzerland (e.g., Schlatter, 1991); Italy (e.g., Cecca et al., 1987); Hungary (e.g., Géczy and Meister, 2007), Romania (e.g., Tibuleac, 2005). North America: Nevada (Smith, 1981). South America and elsewhere: Chile (e.g., Hillebrandt, 2002); Morocco (e.g., Guex et al., 2008).   Localities: F2-24.   164  Genus PALAEOECHIOCERAS Spath, 1929  Type species: Protechioceras spirale TRUEMAN & WILLIAMS, 1927, by original designation. Refigured by GETTY, 1973.   Synonymy: Protechioceras TRUEMAN & WILLIAMS, 1927; Hypechioceras SPATH, 1956.   Description:  Small, evolute forms. Whorl section rounded and depressed in the inner whorls, but becomes compressed with growth, then remains subquadrate. The venter is slightly fastigate or tabulate, and bears a weak, non-sulcate keel. The nucleus is smooth up to about 2 mm, followed by a densely ribbed stage. The ribs are rectiradiate or gently prorsiradiate, can be slightly flexuous. The ribs project forward onto the venter and fade rapidly, or sometimes meet to form chevrons (Smith, 1981; Howarth, 2013).  Remarks:  Palaeoechioceras is the earliest echioceratid in Europe, and is probably derived from Epophioceras. Guex et al. (2008) suggested that Palaeoechioceras is the rootstock for all genera of Echioceradidae other than Gagaticeras. A comprehensive discussion of the genus is given by Getty (1973).   Age and Distribution:  Palaeoechioceras is characteristic of the Oxynotum Zone in Europe. It is recorded from the lower part of the Harbledownense Zone in North America (sensu Smith, 1981). This genus is known from the following areas: Europe and Northern Africa: UK & Austria (Getty, 1972); Hungary (e.g., Géczy and Meister, 2007); Morocco (e.g., Guex et al., 2008). 165  North America: Nevada (Smith, 1981). South America: Chile (Howarth, 2013).   Palaeoechioceras cf. spirale (TRUEMAN & WILLIAMS, 1927) Page 201, Plate 15, Figs. 9-11.    cf. 1886 Arietites doricus SAVI & MENEGHINI – GEYER, p. 247, pl. 3, fig 3.  *cf. 1927 Protechioceras spirale TRUEMAN & WILLIAMS, p. 248, pl. 38, fig. 6.  cf. 1973 Palaeoechioceras spirale TRUEMAN & WILLIAMS – GETTY, p. 9, pl. 1, fig. 2 (refigured holotype). cf. 1973 Palaeoechioceras pierrei SPATH – GETTY, pl. 1, fig. 6 (refigured holotype).  cf. 1981 Palaeoechioceras spirale TRUEMAN & WILLIAMS – SMITH (cum synonymy), p. 169, pl. 3, fig. 5. cf. 1981 Palaeoechioceras aff. spirale TRUEMAN & WILLIAMS – SMITH, p. 171, pl. 3, fig. 6.  cf. 1990 Palaeoechioceras spirale TRUEMAN & WILLIAMS – HOLLINGWORTH et al., p. 166, pl. 1, fig. 5. cf. 1998 Plesechioceras aff. spirale TRUEMAN & WILLIAMS – LACHKAR et al., p. 608, figs. 8.10-8.11. cf. 2008 Palaeoechioceras sp. ind. GUEX et al., p. 87, pl. 17, fig. 9; text-fig. 3.63.  cf. 2013 Palaeoechioceras spirale TRUEMAN & WILLIAMS – HOWARTH, p. 30, figs. 1a-1b (refigured holotype).  cf. 2013 Palaeoechioceras spirale TRUEMAN & WILLIAMS – HOWARTH, p. 30, figs. 1c-1d.   Materials: 6 ex situ specimens from Five Card Draw preserved in limestone.  166   Measurements:  Specimen # D UD U WW WH WWWH PRHW F2-24-05 18.1 9.7 0.54 4.2 4.8 0.88 17 F2-24-06 21.2 11.4 0.54 5.1 5.8 0.88 17 F2-24-07 24.7 13.8 0.56  6.3  19 F2-24-08  13.7  4.8 4.5 1.07 18 F2-24-10 14.9 8.5 0.57    16  Description:  Small, evolute forms. Umbilicus around 55% of diameter. Flanks are rather flat. Whorl section subquadrate, slightly compressed. Umbilical wall is low. Venter is slightly fastigate, and bears a non-sulcate, feeble keel. Ribs are slightly flexuous, rectiradiate or gently prorsiradiate. The ribs swing forward onto the venter and fade away before reaching the keel, forming chevrons. Rib frequency is relatively low for the genus, and increases with growth.   Discussion:  These specimens resemble all the characters of P. spirale except that its rib frequency is relatively lower, and that the smooth nucleus (< 2 mm) is barely discernible due to the limited preservation of the nucleus. The rib frequency is in good agreement with P. aff. spirale in Smith (1981), which has a quite wide range of rib frequency and resembles all other characters of P. spirale. Therefore, the two species are synonymized herein. P. pierrei is also a similar species. Smith (1981) and Lachkar et al. (1998) suggested to synomymize P. pierrei into P. spirale due to their small difference in the whorl sections, which is adopted in this work. Guex et al. (2008), however, prefer to keep P. pierrei by the specimen named P. gr. pierrei, which is much larger in size and has much more compressed whorl section and more blunt ribs than ours.    167  Occurrence and distribution:  P. spirale is recorded from the Oxynotum Zone in Europe. It occurs in association with Paltechioceras boehmi and Oxynoticeras cf. simpsoni from the lower part of the Harbledownense Zone in North America (sensu Smith, 1981). This species is known from the following areas: UK (e.g., Hollingworth et al., 1990), Morocco (e.g., Lachkar et al., 1998), Nevada (Smith, 1981).    168  Echioceratidae gen. et sp. indet. Page 201, Plate 15, Figs. 12-13.   Materials: 4 specimens from Last Creek preserved in calcareous shale.   Measurements:  Specimen # D UD U WW WH WWWH PRHW T 16-01 13.3 5.9 0.44 5.3 4.2 1.26 27 T 16-02 22.8 11.9 0.52 6.5 5.6 1.16 23 T 16-03 27.0 14.2 0.53 9.1 7.3 1.25 26 T 16-04 ~29.8 14.8 0.50 9.5 8.9 1.07 23  Description:  Small, evolute, fairly quickly expanding forms. Umbilicus around 50% of diameter. Whorl section is rounded and weakly depressed (Fig. 6-14). Flanks are convex. The umbilical wall is fairly high and rounded. Venter is convex, and quite smooth, except for a very feeble, non-sulcate keel. Nucleus smooth up to about 1.5 mm, followed by dense ribbing. Ribs are straight to very weakly concave, quite prorsiradiate in the inner whorls, then becomes more rectiradiate on the outer whorl, and not markedly projected forward. The ribs gradually fade out on the venter. The shell surface show fine constrictions. Suture is ceratitic-like. The ventral lobe is very low and smooth, the 1st and 2nd saddles are broad and simple, and the 1st lateral lobe is serrated (Fig. 6-15).     Fig. 6-14 Whorl section of Echioceratidae gen. et sp. indet. Specimens: a. T 16-03; b. T 169  16-04.  Discussion:  This peculiar species resembles Echioceratidae, and could be compared to Palaeoechioceras by its dense ribbing, rounded whorl section, feeble keel and smooth nucleus, but differs from it by a much lower umbilical ratio and the ceratitic-like suture. It also differs from other genera of Echioceratidae by its low umbilical ratio, high whorl expansion rate, and its identical suture, which is unlike the sutures of Echioceratidae (e.g., Getty, 1973; Guex et al., 2008; Howarth, 2013). Rakús (1994) erected a genus, Dudresnayiceras, which can have similar ribbing pattern, ventral characters and ceratitic-like suture, but its suture is offset and asymmetrical (p. 74, text-fig. 5d in Rakús and Guex, 2002). Currently, Dudresnayiceras is still a poorly understood taxon and the relationship with other coeval taxa is unknown.   Occurrence and distribution:  These specimens were collected from the headwaters of Last Creek in association with echioceratids, Harbledownense Zone.   Locality: T 16.    Fig. 6-15 Septal sutures of Echioceratidae gen. et sp. indet. at WH=8.9 mm. Specimen: T 16-04. 170  CHAPTER 7       CONCLUSIONS  This thesis presents a detailed, systematic study of the Sinemurian ammonites (excluding the lowermost and uppermost Sinemurian) from Last Creek, British Columbia and Five Card Draw, Nevada in western North America. A total of 38 species allocated to 15 genera have been identified, described and their stratigraphic ranges determined, including three new species: Tipperoceras n. sp. A, Tmaegoceras obesus   n. sp., Arnioceras n. sp. A. In addition, Echioceratidae gen. et sp. indet. is tentatively introduced as a new genus and species. Lytoceras sp., Coroniceras sp., and Epophioceras sp. are possibly new species but their preservation or paucity does not warrant their formal establishment.  The stratigraphical distribution of these taxa helps to recognize four ammonite zones of the Sinemurian of western North America using the zonation scheme proposed by Taylor et al. (2001): the Involutum, Leslei, Carinatum and Harbledownense zones. The Jamesi Zone in the Upper Sinemurian in Taylor et al. (2001) cannot be recognized in either of the study areas in Canada or United States. With the incorporation of the new data in this work, a revision of the current zonation and an updated definition of the zones are proposed. An updated correlation with the primary standard Northwest European ammonite zonation is also provided.  The precise biostratigraphic control of the measured sections can improve the dating of the lithologic units in the study areas into zone level. In Last Creek, British Columbia, the top of the Castle Pass Member (base of the Little Paradise Member) of the Last Creek Formation in Last Creek corresponds with the top of the Involutum Zone in the Lower Sinemurian. In Five Card Draw, Nevada, the top of the Ferguson Hill Member (base of the Five Card Draw Member) of the Sunrise Formation also corresponds with the top of the Involutum Zone. The top of the Five Card Draw Member (base of the New York Canyon Member) corresponds with the lower part of the Harbledownense Zone.  171  The influence of eustatic changes on the Sinemurian successions in the study areas are investigated by accommodation space equation, paleobathymetry and depositional environment. The Early Sinemurian transgression (T1) is well represented in both Last Creek and Five Card Draw with evidence of strong eustatic control. The mid-Late Sinemurian regression (R1) and Late Sinemurian transgression (T1) are indicated by lithologic changes but lack of sufficient data in Last Creek, whereas they are well represented by the lithologic, paleobathymetric, and depositional changes in Five Card Draw. The ammonite diversity and faunal turnover are compared with the eustatic changes zone by zone. The diversity and turnover maxima in the Leslei Zone in Last Creek is consistent with the Early Sinemurian transgression and the positive carbon isotope excursion which is mostly likely driven by a global increase in primary productivity.  The significant contrast between the depositional environments in Last Creek and Five Card Draw is suggested by carbon and osmium isotope profiles. Last Creek was a magmatic arc environment where the seawater has free circulation with the open ocean whereas Five Card Draw was a restricted continental margin basin which is highly affected by continental influx that might have masked any possible global isotopic signature. The contrast of the ammonite diversity and faunal turnover in these two areas may also reflect difference in depositional environments. The pattern of diversity and faunal turnover in Last Creek is similar with that of the Tethyan Realm and corresponds with eustatic sea level change whereas the pattern of Five Card Draw appears to be not affected by eustasy.     172    PLATES  173    174         EXPLANATION OF PLATE 1  Figure 1 Fucinites sicilianus GUGENBERGER, 1936  Specimen T 02, glacial float from locality T 02, head waters of Last Creek, Last Creek Formation, probably Involutum Zone.   ×0.49  175     176   EXPLANATION OF PLATE 2 (All figures natural size unless otherwise indicated) Figure 1-4 Ectocentrites leslei (TAYLOR, GUEX & RAKÚS, 2001)  1. Specimen F1-21-08, latex cast of compressed external mold, section F1, locality F1-21, Five Card Draw, Sunrise Formation, Leslei Zone.   2. Specimen F1-27-05, latex cast of compressed external mold, section F1, locality F1-27, Five Card Draw, Sunrise Formation, top of Leslei Zone.  3. Specimen F-13-I6-1, compressed external mold from locality F-13-I6, Five Card Draw, Sunrise Formation, Leslei Zone.  4. T 12, interval mold from locality T 12, Paradise Creek, Last Creek Formation, Leslei Zone.  Figure 5 Lytoceras sp.   Specimen T 14, internal mold with shell from locality T 14, headwaters of Last Creek, Last Creek Formation, Leslei Zone.  Figure 6-8 Tipperoceras mullerense TAYLOR, 1998   6. Specimen F3-11, 7. Specimen F3-12, 8. Specimen F3-13, all internal molds from Five Card Draw, Ferguson Hill Member, Sunrise Formation, Involutum Zone.  Figure 9 Tipperoceras n. sp. A   Specimen T 07, internal mold from locality T 07, ex situ, headwaters of Last Creek, Last Creek Formation, probably Involutum Zone. Figure 10-11 Tmaegoceras nudaries TAYLOR, 1998   10. Specimen F3-09, 11. Specimen F3-10, both are internal molds from Five Card Draw, Ferguson Hill Member, Sunrise Formation, Involutum Zone.    177      178  EXPLANATION OF PLATE 3  Figure 1 Tipperoceras mullerense TAYLOR, 1998  Specimen T 01, internal mold from locality T 01, ex situ, headwaters of Last Creek, probably Involutum Zone.     ×0.49     179      180  EXPLANATION OF PLATE 4 (All figures natural size unless otherwise indicated) Figure 1-2 Tmaegoceras crassiceps POMPECKJ, 1901  1. Specimen T 03-02, internal molds from locality T 03, ex situ, headwaters of Last Creek, Last Creek Formation, Involutum Zone.  2. Specimen T 09, internal molds from locality T 09, ex situ, headwaters of Last Creek, Last Creek Formation, Involutum Zone.  Figure 3 Tmaegoceras cf. latesulcatum (HAUER, 1856)   Specimen T 06, internal mold from locality T 06, ex situ, headwaters of Last Creek, Last Creek Formation, Involutum Zone.  Figure 4 Tmaegoceras obesus n. sp.   Specimen F3-08, holotype, internal mold from Five Card Draw, Ferguson Hill Member, Sunrise Formation, Involutum Zone.      181      182  EXPLANATION OF PLATE 5 (All figures natural size unless otherwise indicated) Figure 1 Coroniceras sp.   Specimen L1-01-02, internal mold from section L1, locality L1-01, Last Creek, Last Creek Formation, Involutum Zone.  Figure 2-3 Coroniceras cf. lyra HYATT, 1867   2. Specimen T 08-01, internal molds from locality T 08, ex situ, head waters of Last Creek, Last Creek Formation, Involutum Zone.   3. Specimen L1-03-04 FL, internal mold from section L1, ex situ, locality L1-03, Last Creek, Last Creek Formation, Involutum Zone.  Figure 4 Coroniceras multicostatum (SOWERBY, 1824)  Specimen L1-04-01, internal mold from section L1, locality L1-04, Last Creek, Last Creek Formation, Involutum Zone.      183      184  EXPLANATION OF PLATE 6 (All figures natural size unless otherwise indicated) Figure 1, 3 Coroniceras cf. mutabile MACCHIONI, SMITH & TIPPER, 2005  1. Specimen F3-14, internal mold from Five Card Draw, Ferguson Hill Member, Sunrise Formation, Involutum Zone.    3. Specimen L1-03-01, internal mold from section L1, locality L1-03, Last Creek, Last Creek Formation, Involutum Zone.  Figure 2 Coroniceras charlesi DONOVAN, 1955  Specimen T 08-02, internal mold from locality T 08, headwaters of Last Creek, Last Creek Formation, Involutum Zone. Figure 4-7 Arnioceras ceratitoides (QUENSTEDT, 1848)   4. Specimen F1-27-40-1, 5. Specimen F1-27-66, 6. Specimen F1-27-65-1, all of them are compressed internal mold from section F1, locality F1-27, Five Card Draw, Sunrise Formation, top of Leslei Zone.    7. Specimen F2-01, latex of a compressed external mold from section F2, locality F2-01, Five Card Draw, Sunrise Formation, base of Carinatum Zone.       185      186  EXPLANATION OF PLATE 7  Figure 1 Coroniceras cf. involutum TAYLOR, 1998  Specimen F1-01, partially compressed internal mold from section F1, locality F1-01, Five Card Draw, Sunrise Formation, Involutum Zone. ×0.12     187      188  EXPLANATION OF PLATE 8 (All figures natural size unless otherwise indicated) Figure 1-3 Arnioceras ceratitoides (QUENSTEDT, 1848)  1. Specimen L2-06-01, compressed internal mold from section L2, locality L2-06, Last Creek, Last Creek Formation, Leslei Zone.  2. Specimen L2-03-07, internal mold from section L2, locality L2-03, Last Creek, Last Creek Formation, Leslei Zone.  3. Specimen L2-04, plasticine cast of the external mold from section L2, locality L2-04, Last Creek, Last Creek Formation, Leslei Zone. Figure 4-6 Arnioceras arnouldi (DUMORTIER, 1867)  4. Specimen F1-05, internal mold from section F1, locality F1-05, Five Card Draw, Sunrise Formation, Involutum Zone.  5. Specimen F3-03, internal mold from Five Card Draw, Ferguson Hill Member, locality F3-03, Sunrise Formation, Involutum Zone.  6. Specimen F1-03-00, internal mold from section F1, locality F1-03, Five Card Draw, Sunrise Formation, Involutum Zone.    189      190  EXPLANATION OF PLATE 9 (All figures natural size unless otherwise indicated) Figure 1-2 Arnioceras semicostatum (YOUNG & BIRD, 1828)  1. Specimen T 10, internal mold from locality T 10, ex situ, headwaters of Last Creek, Last Creek Formation, Involutum to Leslei Zones.  2. Specimen T 03-01, internal mold from locality T 03, ex situ, headwaters of Last Creek, Last Creek Formation, Involutum Zone. Figure 3 Arnioceras cf. arnouldi (DUMORTIER, 1867)  Specimen L2-07-03, partially compressed internal mold from section L2, locality L2-07, Last Creek, Last Creek Formation, Leslei Zone. Figure 4 Arnioceras arnouldi (DUMORTIER, 1867)  Specimen F3-07, internal mold from locality F3-07, Five Card Draw, Ferguson Hill Member, Sunrise Formation, Involutum Zone.    191      192  EXPLANATION OF PLATE 10 (All figures natural size unless otherwise indicated) Figure 1 Arnioceras cf. oppeli GUÉRIN-FRANIATTE, 1966  Specimen L2-05, internal mold from section L2, locality L2-05, Last Creek, Last Creek Formation, Leslei Zones. Figure 2-3 Arnioceras densicosta (QUENSTEDT, 1884)  2. Specimen L1-09, internal mold from section L1, locality L1-09, Five Card Draw, Sunrise Formation, Leslei Zone.   3. Specimen F1-07, latex cast of the external mold from section F1, ex situ, locality F1-07, Five Card Draw, Sunrise Formation, top of Involutum Zone.  Figure 4-5 Arnioceras densicosta (QUENSTEDT, 1884)  4. Specimen F3-02, 5. Specimen F3-06, internal mold from Five Card Draw, Ferguson Hill Member, Sunrise Formation, Involutum Zone. Figure 6 Arnioceras miserabile (QUENSTEDT, 1858)  Specimen F3-05, internal mold Five Card Draw, Ferguson Hill Member, Sunrise Formation, Involutum Zone. Figure 7-8 Arnioceras miserabile (QUENSTEDT, 1858)  7. Specimen F1-27-01, 8. Specimen F1-27-02, both are flattened internal mold from section F1, locality F1-27, Five Card Draw, Sunrise Formation, top of Leslei Zone. Figure 9-10 Arnioceras miserabile (QUENSTEDT, 1858)  9. Specimen F-13-LJ3-2, compressed external mold, 10. Specimen F-13-LJ3-3, latex cast of a flattened external mold, both ex situ, Five Card Draw, Sunrise Formation, Leslei Zone    193      194  EXPLANATION OF PLATE 11 (All figures natural size unless otherwise indicated) Figure 1-4 Arnioceras miserabile (QUENSTEDT, 1858)  1. Specimen T 11-02, 2. Specimen T 11-06, 4. Specimen T 11-07, all internal molds from locality T 11, headwaters of Last Creek, Last Creek Formation, Leslei Zone.  3. T 13-02, internal mold from locality T 13, headwaters of Last Creek, Last Creek Formation, Leslei Zone. Figure 5-6 Arnioceras n. sp. A  5. Specimen T 11-04, 6. Specimen T 11-03, both are internal molds from locality T 11, headwaters of Last Creek, Last Creek Formation, Leslei Zone. Figure 7 Caenisites turneri (SOWERBY, 1824)   Specimen L2-03, internal mold from section L2, locality L2-03, Last Creek, Last Creek Formation, upper part of Leslei Zone. Figure 8 Caenisites sp.  Specimen L2-02-01, fragment of an internal mold from section L2, locality L2-02, Last Creek, Last Creek Formation, upper part of Leslei Zone.    195      196  EXPLANATION OF PLATE 12  Figure 1 Caenisites brooki (SOWERBY, 1818)  Specimen T 15, plaster cast of an internal mold from an isolated locality T 15, ex situ, headwaters of Last Creek, Last Creek Formation, probably Leslei Zone. ×0.49     197      198  EXPLANATION OF PLATE 13 (All figures natural size unless otherwise indicated) Figure 1-2 Asteroceras cf. varians FUCINI, 1903  1. Specimen F2-14-01, 2. Specimen F2-14-02, both are flattened internal mold from section F2, locality F2-14, Five Card Draw, Sunrise Formation, Carinatum Zone. Figure 3-4 Asteroceras sp.  3. Specimen F1-27-52, internal mold from section F1, locality F1-27, Five Card Draw, Sunrise Formation, base of Carinatum Zone.  4. Specimen F-13-MJ3-5, internal mold from locality F-13-MJ3, Five Card Draw, Five Card Draw Member, Sunrise Formation, Carinatum Zone.  Figure 5 Asteroceras cf. margarita (PARONA, 1896)   Specimen L-12-I5-1, internal mold from locality L-12-I5, headwaters of Last Creek, Last Creek Formation, probably Carinatum Zone.     199      200  EXPLANATION OF PLATE 14 (All figures natural size unless otherwise indicated) Figure 1 Eparietites ex gr. impedens (YOUNG & BIRD, 1928)  Specimen F-13-UJ3-1, latex cast of an external mold from locality F-13-UJ3, ex situ, Five Card Draw, Five Card Draw Member, Sunrise Formation, Carinatum Zone.  Figure 2-3 Epophioceras cf. wendelli TAYLOR, GUEX & RAKÚS, 2001  2. Specimen F2-06-08, latex cast of an external mold from section F2, locality F2-06, Five Card Draw, Sunrise Formation, Carinatum Zone.  3. Specimen F2-19-04, compressed internal mold from section F2, locality F2-19, Five Card Draw, Sunrise Formation, near the top of Carinatum Zone. Figure 4, 6-7 Epophioceras carinatum SPATH, 1924  4. Specimen F1-29-05, compressed internal mold from section F1, locality F1-29, Five Card Draw, Sunrise Formation, lower part of Carinatum Zone.    6. Specimen F1-28, compressed internal mold from section F1, locality F1-28, Five Card Draw, Sunrise Formation, lower part of Carinatum Zone.   7. Specimen F-13-UJ3-3, compressed internal mold from locality F-13-UJ3, ex situ, Five Card Draw, Five Card Draw Member, Sunrise Formation, Carinatum Zone. Figure 5 Epophioceras cf. carinatum SPATH, 1924  Specimen F-13-I1-1, latex cast of an external mold from locality F-13-I1, ex situ, Five Card Draw, Five Card Draw Member, Sunrise Formation, Carinatum Zone.     201      202  EXPLANATION OF PLATE 15 (All figures natural size unless otherwise indicated) Figure 1-3 Epophioceras sp.  1. Specimen F1-09, compressed internal mold from section F1, locality F1-09, ex situ, Five Card Draw, Sunrise Formation, Carinatum Zone.  2. Specimen F2-13-01, compressed internal mold from section F1, locality F2-13, Five Card Draw, Sunrise Formation, Carinatum Zone.   3. Specimen F-13-MJ3-13, compressed internal mold from locality F-13-MJ3, ex situ, Five Card Draw, Five Card Draw Member, Sunrise Formation, Carinatum Zone.  Figure 4-6 Paltechioceras cf. harbledownense (CRICKMAY, 1928)  4. Specimen F2-20, latex cast of an external mold from section F2, locality F2-20, Five Card Draw, Sunrise Formation, base of Harbledownense Zone.   5. Specimen N-12-J3-7, compressed internal mold from locality N-12-J3, entrance of New York Canyon, Harbledownense Zone.   6. Specimen F1-38-02, compressed internal mold from section F1, locality F1-38, Five Card Draw, Sunrise Formation, Harbledownense Zone.  Figure 7-8 Paltechioceras boehmi (HUG, 1899)  7. Specimen F2-24-02, latex cast of an external mold, 8. Specimen F2-24-03, internal mold, both are from section F2, locality F2-24, ex situ, Five Card Draw, Sunrise Formation, Harbledownense Zone.  203  Figure 9-11 Palaeoechioceras cf. spirale (TRUEMAN & WILLIAMS, 1927)  9. Specimen F2-24-05, 10. F2-24-06, 11. F2-24-08, all internal molds from section F2, locality F2-24, Five Card Draw, Sunrise Formation, Harbledownense Zone. Figure 12-13 Echioceratidae gen. et sp. indet.   12. Specimen T 16-03, 13. Specimen T 16-04, both are internal molds from locality T 16, headwaters of Last Creek, Last Creek Formation, Harbledownense Zone.         204  REFERENCES ABERHAN, M. 1999. Terrane history of the Canadian Cordillera: estimating amounts of latitudinal displacement and rotation of Wrangellia and Stikinia. Geological Magazine, 136:481–492. ALKAYA, F., AND C. MEISTER. 1995. Liassic ammonites from the central and eastern Pontides (Ankara and Kelkit areas, Turkey). Revue de Paléobiologie, 14:125–193. ALLÈGREA, C. J., AND J.-M. LUCKA. 1980. Osmium isotopes as petrogenetic and geological tracers. Earth and Planetary Science Letters, 48:148–154. ARKELL, W. J., W. M. FURNISH, B. KUMMEL, A. K. MILLER, R. C. MOORE, O. H. SCHINDEWOLF, P. C. SYLVESTER-BRADY, AND C. W. WRIGHT. 1957. Mesozoic Ammonoidea; p. 1–490. In R. C. Moore (ed.), Treatise on invertebrate paleontology. The Geological Society of America & University of Kansas Press, Lawrence. ARP, G., D. PERSOH, A. REIMER, J. REITNER, AND M. SOSNITZA. 2000. Lias-Fossilien aus der Tongrube Eichenberg, Nordhessen. Fossilien, 17:108–113. ASGAR-DEEN, M., R. L. HALL, J. CRAIG, AND C. RIEDIGER. 2003. New biostratigraphic data from the Lower Jurassic Fernie Formation in the subsurface of west-central Alberta and their stratigraphic implications. Canadian Journal of Earth Sciences, 40:45–63. BAYLE, E. 1878. Explication de La Carte Géologique de La France, IV, Atlas, Part 1, Fossiles Des Principaux Terrains. Imprimerie Nationale, Paris, 158 p. BENGSTON, P. 1988. Open nomenclature. Palaeontology, 31:223–227. BLAU, J. 1998. Monographie der Ammoniten des Obersinemuriums (Lotharingium, Lias) der Lienzer Dolomiten (Österreich): Biostratigraphie, Systematik und Paläobiogeographie. Revue de Paléobiologie, 17:177–285. BLAU, J., AND C. MEISTER. 2000. Upper Sinemurian ammonite successions based on 41 faunal horizons: an attempt at worldwide correlations. GeoResearch Forum, 6:3–12. BLAU, J., C. MEISTER, R. SCHLATTER, AND R. SCHMIDT-EFFING. 2002. Nomenclatural and taxonomical remards on a Asteroceratinae (Ammonoidea): Euerbenites nom. nov. for Erbenites BLAU, MEISTER, SCHLATTER & SCHMIDT-EFFING, 2001. Revue de Paléobiologie, 21:411–412.  205  BLAU, J., C. MEISTER, R. SCHLATTER, AND R. SCHMIDT-EFFING. 2003. Ammonites from the Lower Jurassic (Sinemurian) of Tenango de Doria (Sierra Madre Oriental, Mexico). Part III: Echioceratidae. Revue de Paléobiologie, 22:421–437. BLAU, J., C. MEISTER, R. SCHMIDT-EFFING, AND A. B. VILLASEÑOR. 2008. A new fossiliferous site of Lower Liassic (Upper Sinemurian) marine sediments from the southern Sierra Madre Oriental (Puebla, Mexico): ammonite fauna, biostratigraphy, and description of Ectocentrites hillebrandti new species. Revista Mexicana de Ciencias Geológicas, 25:402–407. BÖHM, F., O. EBLI, L. KRYSTYN, H. LOBITZER, M. RAKÚS, AND M. SIBLÍK. 1999. Fauna, stratigraphy and depositional environment of the Hettangian-Sinemurian (Early Jurassic) of Adnet (Salzburg, Austria). Abhandlunegn Der Geologischen Bundesanstalt, 56:143–271. BONARELLI, G. 1899. Cefalopodi Sinemuriani dell’Appennino Centrale. Palaeontographia Italica, 5:55–83. BOURILLOT, R., P. NEIGE, A. PIERRE, AND C. DURLET. 2008. Early-Middle Jurassic Lytoceratid ammonites with constrictions from Morocco: palaeobiogeographical and evolutionary implications. Palaeontology, 51:597–609. BRAGA, J.-C., A. MARTIN-ALGARRA, AND P. RIVAS. 1984. Hettangian and Sinemurian of Baños de Alhama de Granada: reference section for the West-Mediterranean Hettangian (Betic Cordillera, Southern Spain). Geobios, 17:269–276. BRAGA, J.-C., A. MARTIN-ALGARRA, AND P. RIVAS. 1985. Ammonites du Lias inférieur (Sinémurien-Lotharingien) de Sierra Harana (Cordillères bétiques, Espagne). Les Cahiers de l’Institut Catholique de Lyon, 14:85–101. BUCKMAN, S. S. 1911. Yorkshire Type Ammonites, Vol.1, Parts 3-5. Wheldon & Wesley, London, 23–44 p. BUCKMAN, S. S. 1912. Yorkshire Type Ammonites, Vol.1, Parts 6-8. Wheldon & Wesley, London, 23–44 p. BUCKMAN, S. S. 1918. Jurassic chronology: I-Lias. Quarterly Journal of the Geological Society of London, 73:257–327. BUCKMAN, S. S. 1919. Yorkshire Type Ammonites, Vol. 2, Part 18. Wheldon & Wesley, London, 15–16 p.  206  BUCKMAN, S. S. 1924. Yorkshire Type Ammonites, Vol.5, Parts 44-48. Wheldon & Wesley, London, 5–48 p. BUCKMAN, S. S. 1926. Yorkshire Type Ammonites, Vol.6, Parts 53-55. Wheldon & Wesley, London, 5–42 p. BUCKMAN, S. S. 1927. Yorkshire Type Ammonites, Vol.6, Parts 62-63. Wheldon & Wesley, London, 1–62 p. BURCHFIEL, B. C., AND G. A. DAVIS. 1972. Structural framework and evolution of the southern part of the Cordilleran orogen, western United States. American Journal of Science, 272:97–118. BURCHFIEL, B. C., AND G. A. DAVIS. 1975. Nature and controls of Cordilleran orogenesis, western United States: Extensions of an earlier synthesis. American Journal of Science, 275:363–396. CAIRNES, C. E. 1943. Geology and mineral deposits of Tyaughton Lake map area, British Columbia (report and map). Geological Survey of Canada Paper, 43-15:1–39. CANAVARI, M. 1899. Memorie Di Paleontologia. Palaeontographia Italica, 5:1–239. CARUTHERS, A. H., D. R. GRÖCKE, AND P. L. SMITH. 2011. The significance of an Early Jurassic (Toarcian) carbon-isotope excursion in Haida Gwaii (Queen Charlotte Islands), British Columbia, Canada. Earth and Planetary Science Letters, 307:19–26. CASSINIS, G., AND G. CANTALUPPI. 1967. Nuovi dati paleontologici per una più approfondita conoscenza del limite cronologico superiore della “Corna” di Botticino (Brescia). Atti dell’Istituto Geologico Della Università Di Pavia, 18:51–64. CATUNEANU, O. 2006. Principles of Sequence Stratigraphy. Elsevier, Amsterdam, Boston, Heidelberg, London, New York, Oxford, Paris, San Diego, San Francisco, Singapore, Sydney, Tokyo, 386 p. CECCA, F., J.-L. DOMMERGUES, R. MOUTERDE, AND G. PALLINI. 1987. Ammonites méditerranéennes du Lotharingien de Gorgo à Cerbara (M. Nerone, Apennin des Marches, Italie). Les Cahiers de l’Université Catholique de Lyon, Série Sciences, 67–82. COHEN, A. S., AND A. L. COE. 2007. The impact of the Central Atlantic Magmatic Province on climate and on the Sr- and Os-isotope evolution of seawater. Palaeogeography, Palaeoclimatology, Palaeoecology, 244:374–390.  207  COHEN, A. S., A. L. COE, J. M. BARTLETT, AND C. J. HAWKESWORTH. 1999. Precise Re–Os ages of organic-rich mudrocks and the Os isotope composition of Jurassic seawater. Earth and Planetary Science Letters, 167:159–173. COLBACH, R., S. GUÉRIN-FRANIATTE, AND R. MAQUIL. 2003. Unremarquable site fossilifère dans le Sinémurien inférieur de Bertrange (Grand-Duché de Luxembourg). Ferrantia, 36:53–64. COPE, J. C. W. 1991. Ammonite faunas of the Ammonitico Rosso of the Pontide Mountains, northern Anatolia. Geologica Romana, 27:303–325. CORNA, M. 1985. Le Lias Du Jura Méridional, Paléontologie Stratigraphique Du Sinémurien, Approche Paléoécologique. Université Claude Bernard Lyon, 246 p. CORNA, M. 1987. Les horizons sinémuriens du Calcaire à gryphées du jura méridional Français (Zone à Conybeari-Zone à Obtusum). Geobios, 20:531–536. CORNA, M., AND J.-L. DOMMERGUES. 1995. Les ammonites du Sinémurien de Mandelot (Côte-d’Or, France).Approches biostratigraphique, morphologique et ontogénétique. Geobios, 28:17–47. CORNA, M., J.-L. DOMMERGUES, A. GUIFFRAY, AND L. BULOT. 1990. Quelques points remarquables dans le Sinémurien des Alpes de Provence (France); précisions biostratigraphiques et paléontologiques. Géologie Méditerranéenne, 17:3–37. CORNA, M., J.-L. DOMMERGUES, C. MEISTER, AND K. N. PAGE. 1997. Les faunes d’ammonites du Jurassique inférieur (Hettangien, Sinémurien et Pliensbachien) au nord du massif des Écrins (Oisans, Alpes occidentales). Revue de Paléobiologie, 16:321–409. CORVALAN, J. I. 1962. Early Mesozoic Biostratigraphy of the Westgate Area, Churchill County, Nevada. PhD Thesis. Stanford University, 224 p. CRAFFORD, A. E. J. 2007. Geologic Map of Nevada: US Geological Survey Data Series 249. US Department of the Interior US Geological Survey, Anchorage, Denver, 46 p. CRAFFORD, A. E. J. 2008. Paleozoic tectonic domains of Nevada: an interpretive discussion to accompany the geologic map of Nevada. Geosphere, 4:260–291. CREASER, R. A., D. A. PAPANASTASSIOU, AND G. J. WASSERBURG. 1991. Negative thermal ion mass spectrometry of osmium, rhenium and iridium. Geochimica et Cosmochimica Acta, 55:397–401.  208  CRICK, G. C. 1902. VI.—Note on the genus Tmaegoceras, Hyatt. Geological Magazine (Decade IV), 9:127–128. CRICKMAY, C. H. 1928. The stratigraphy of Parson Bay, British Columbia. University of California Publications in Paleontological Sciences, 18:1–74. CUMMING, V. M., S. W. POULTON, A. D. ROONEY, AND D. SELBY. 2013. Anoxia in the terrestrial environment during the late Mesoproterozoic. Geology, 41:583–586. DEAN, W. T., D. T. DONOVAN, AND M. K. HOWARTH. 1961. The Liassic ammonite zones and subzones of the North-west European province. Bulletin of British Museum (Natural History), 4:435–505. DEINES, P. 2002. The carbon isotope geochemistry of mantle xenoliths. Earth-Science Reviews, 58:247–278. DERA, G., J. PRUNIER, P. L. SMITH, J. W. HAGGART, E. POPOV, A. GUZHOV, M. ROGOV, D. DELSATE, D. THIES, G. CUNY, E. PUCÉAT, G. CHARBONNIER, AND G. BAYON. 2014. Nd isotope constraints on ocean circulation, paleoclimate, and continental drainage during the Jurassic breakup of Pangea. Gondwana Research (in press). DOMMERGUES, J.-L. 1982. Justification du genre Plesechioceras Trueman et Williams 1925 Ammonitina, Lias. Implications biostratigraphiques et paleontologiques. Bulletin de La Societe Geologique de France, 24:379–382. DOMMERGUES, J.-L. 1993. Les ammonites du Sinémurien supérieur de Bourgogne (France): biostratigraphie et remarques paléontologiques. Revue de Paléobiologie, 12:67–173. DOMMERGUES, J.-L., AND C. MEISTER. 1989. Succession des faunes d’ammonites du Sinémurien supérieurdans le Chablais méridional et les Klippes de Savoie (Préalpes Médianes, Haute-Savoie, France). Geobios, 22:455–483. DOMMERGUES, J.-L., AND M. GUIOMAR. 2011. La «Dalle à ammonites de Digne » (Réeserve Naturelle Géologique de Haute Provence, France). Étude d’un site fossilifère d’importance patrimoniale. Revue de Paléobiologie, 30:261–293. DOMMERGUES, J.-L., C. MEISTER, AND M. METTRAUX. 1990. Succession des faunes d’Ammonites du Sinémurien et du Pliensbachien dans les Préalpes médianes de Suisse romande (Vaud et Fribourg). Geobios, 23:307–341.  209  DOMMERGUES, J.-L., A. FERRETTI, AND C. MEISTER. 1994. Les faune d’ammonites du Sinémurien de l'Apennin central (Marches et Toscane, Italie). Bollettino Della Società Paleontologica Italiana, 33:13–42. DOMMERGUES, J.-L., C. MEISTER, AND F. BÖHM. 1995. New data on Austroalpine Liassic ammonites from the Adnet quarries and adjacent areas (Oberösterreich, Northern Calcareous Alps). Jahrbuch Der Geologischen Bundesanstalt, 138:161–205. DOMMERGUES, J.-L., C. MEISTER, AND E. JAILLARD. 2004. Ammonites de la formation Santiago de la zone subandine du S-E de l’equateur (Jurassique inférieur, Sinémurien). Revue de Paléobiologie, 23:355–371. DOMMERGUES, J.-L., C. MEISTER, AND G. MANATSCHAL. 2012. Early Jurassic ammonites from Bivio (Lower Austroalpine unit) and Ardez (Middle Penninic unit) areas: a biostratigraphic tool to date the rifting in the Eastern Swiss Alps. Revue de Paléobiologie, 11:43–52. DOMMERGUES, J.-L., N. FOREST-BIZE, J.-P. GELY, AND J.-P. LOREAU. 2005. Les faunes d'ammonites du Sinémurien supérieur (Jurassique inférieur) du Perron des Encombres (Alpes occidentales françaises, Zone subbriançonnaise entre Arc et Isère). Revue de Paléobiologie, 24:673–696. DOMMERGUES, J.-L., G. CATTANEO, R. AÏTE, AND J.-P. GÉLARD. 2008. Les ammonites de l’Hettangien, du Sinémurien et du Pliensbachien inférieur de la Dorsale de Grande Kabylie (Algérie). Geodiversitas, 30:539–576. DONOVAN, D. T. 1952. The ammonites of the Blue Lias of the Bristol District. Part I. Psiloceratidae and Schlotheimidae. The Annals and Magazine of Natural History, Series 12, 5:629–655. DONOVAN, D. T. 1953. Euasteroceras gen. nov., a new generic name for a well-known lower Liassic ammonite. Proceedings of the Geological Society of London, 1503:13–14. DONOVAN, D. T. 1955. Révision des éspèces décrites dans la “Monographie des Ammonites” (Lias inférieur) de P. Reynès. Mémoires de La Société Géologique de France (new Series), 73:1–47. DONOVAN, D. T. 1987. Evolution of the Arietitidae and their descendants. Cahiers Institut Catholique Lyon, Série Scientifique 1, 1:123–138.  210  DONOVAN, D. T., A. HORTON, AND H. C. IVIMEY-COOK. 1979. The transgression of the Lower Lias over the northern flank of the London Platform. Journal of the Geological Society, 136:165–173. DONOVAN, D. T., J. H. CALLOMON, AND M. K. HOWARTH. 1981. Classification of the Jurassic Ammonitina; p. 101–156. In M. R. House and J. R. Senior (eds.), The Ammonoidea: the Evolution, Classification, Mode of Life and Geological Usefulness of a Major Fossil Group. The Systematic Association Special Volume, No. 18. Academic Press, London; New York. DONOVAN, D. T., M. L. K. CURTIS, AND T. R. FRY. 2005. The lower part of the Lias Group in south Gloucestershire: zonal stratigraphy and structure. Proceedings of the Geologists’ Association, 116:45–59. DRESNAY, R. D. 1988. Répartition des dépôts carbonatés du Lias inférieur et moyen le long de la côte atlantique du Maroc: conséquences sur la paléogéographie de l’Atlantique naissant. Journal of African Earth Sciences (and the Middle East), 7:385–396. DUMORTIER, E. 1867. Etudes Paléontologiques Sur Les Dépôts Jurassiques Du Bassin Du Rhône, 2e Partie, Lias Inférieur. Savy, F., Paris, 256 p. EDMUNDS, M., M. VARAH, AND A. BENTLEY. 2003. The ammonite biostratigraphy of the Lower Lias “Armatum Bed” (Upper Sinemurian-Lower Pliensbachian) at St Peter’s Field, Radstock, Somerset. Proceedings of the Geologists’ Association, 114:65–96. ERBEN, H. K. 1956. El jurásico inferior de México y sus amonitas. XX Congreso Geologico Internacional, Mexico, 393p. ERBEN, H. K., AND W. HAAS. 1985. Stratigraphie und Ammonitenfauna der Pucara-Gruppe (Obertrias-Unterjura) von Nord-Peru. Palaeontographica Abteilung A Band A188, 153–201. ESSER, B. K., AND K. K. TUREKIAN. 1993. The osmium isotopic composition of the continental crust. Geochimica et Cosmochimica Acta, 57:3093–3104. FEDERICI, P. R. 1968. Fossili Sinemuriani della Liguria orientale. Memorie Della Societa Geologica Italiana, 7:107–127. FERGUSON, H. G., AND S. W. MULLER. 1949. Structural Geology of the Hawthorne and Tonopah Quadrangles, Nevada. US Geological Survey Professional Paper, 216:1–68.  211  FIEGE, K. 1929. Biostratigraphie der Arietitenschichten Nordwestdeutschlands und Württembergs. Palaeontographica, 71:67–116. FREBOLD, H. 1951. Contributions to the palaeontology and stratigraphy of the Jurassic Systems in Canada. Geological Survey of Canada, Bulletin, 18:1–54. FREBOLD, H. 1967. Hettangian ammonite faunas of the Taseko Lakes area, British Columbia. Geological Survey of Canada Bulletin, 158:1–35. FREBOLD, H., AND H. W. TIPPER. 1970. Status of the Jurassic in the Canadian Cordillera of British Columbia, Alberta, and southern Yukon. Canadian Journal of Earth Sciences, 7:1–21. FREBOLD, H., AND T. P. POULTON. 1977. Hettangian (Lower Jurassic) rocks and faunas, northern Yukon Territory. Canadian Journal of Earth Sciences, 14:89–101. FUCINI, A. 1902. Cefalopodi Liassici del Monte di Cetona. Parte Due. Palaeontographia Italica, 8:131–217. FUCINI, A. 1903. Cephalopodi liassici del Monte di Cetona. Parte Terza. Palaeontographia Italica, 9:125–185. FÜLÖP, J. 1976. The Mesozoic Basement Horst Blocks of Tata. Institutum Geologicum Hungaricum, Budapestini, 228 p. GABB, W. M. 1869. Descriptions of some secondary fossils from the Pacific states. American Journal of Conchology, 5:5–18. GALLOWAY, W. E. 1989. Genetic stratigraphic sequences in basin analysis I: architecture and genesis of flooding-surface bounded depositional units. AAPG Bulletin, 73:125–142. GEBHARD, G., AND R. SCHLATTER. 1977. Über das Vorkommen von Tmaegoceras Hyatt (Ammonoidea) im Lias Europas. Stuttgarter Beiträge Zur Naturkunde B-22, 1–15. GÉCZY, B. 1972a. Ammonite faunae from the Lower Jurassic standard profile at Lókút, Bakony Mountains, Hungary. Annales Universitatis Scientiarium Budapestinensis de Rolando Eötvös Nominatae (Geologica), 15. GÉCZY, B. 1972b. The Sinemurian in the Bakony Mountains. Acta Geologica Hungarica, 16:251–265.  212  GÉCZY, B., AND C. MEISTER. 2007. Les ammonites du Sinémurien et du Pliensbachien inférieur de la montagne du Bakony (Hongrie). Revue de Paléobiologie, 26:137–305. GETTY, T. A. 1972. Revision of the Jurassic Family Echioceratidae. PhD Thesis. University of London, 321 p. GETTY, T. A. 1973. A revision of the generic classification of the family Echinoceratidae (Cephalopoda, Ammonoidea)(Lower Jurassic). University of Kansas Paleontological Contributions, Paper, 63:1–38. GEYER, G. 1886. Über die liasischen cephalopoden des Hierlatz bei Hallstatt. Abhandlungen Der Kaiserlich-Königlichen Geologischen Reichsanstalt, Wien, 12:213–286. GEYER, O. F. 1973. Das präkretazische Mesozoikum von Kolumbien. Geologisches Jahrbuch, Reihe B, 5:1–155. GEYER, O. F. 1974. Der Unterjura Santiago-Formation von Ekuador. Neues Jb Geol Paleont Abh, 9:525–541. GEYER, O. F. 1976. La Fauna de amonites del perfil típico de la Formación Morrocoyal. Primer Congreso Colombiano de Geologia Memorias, 111–133. GEYER, O. F. 1979. Ammoniten aus dem tiefen Unterjua von Nord-Peru. Paläontologische Zeitschrift, 53:198–213. GOLONKA, J. 2007. Late Triassic and Early Jurassic palaeogeography of the world. Palaeogeography, Palaeoclimatology, Palaeoecology, 244:297–307. GOTSANYUK, G., AND M. MURALI. 2009. Hettangian-Sinemurian ammonites of the Piennine Zone of the Ukrainian Carpathians (in Ukranian). ПАЛЕОНТОЛОГІЧНИЙ ЗБІРНИК, 41:22–26. GRADSTEIN, F. M., J. G. OGG, M. D. SCHMITZ, AND G. M. OGG (EDS.). 2012. The Geologic Time Scale 2012. Elsevier, Oxford, UK; Amsterdam, Netherlands; Waltham, USA, 1176 p. GRUNER, M. 1997. Dynamische Paläoökologie Und Taxonomische Bearbeitung Des Unterjura (Hettangium Bis Unteres Sinemurium) Auf Der Schwäbischen Alb. Inst. für Geologie und Paläontologie, Stuttgart, 349 p.  213  GUÉRIN-FRANIATTE, S. 1966. Ammonites Du Lias Inférieur de France. Psiloceratidae: Arietitidae. Centre National de la Recherche Scientifique, Paris, 455 p. GUÉRIN-FRANIATTE, S. 1994. Biostratigraphie et paléobiogéographie des ammonites. Une synthese pour le Lias inférieur de France. Geobios, 27:265–273. GUEX, J. 1980. Remarques préliminaires sur la distribution stratigraphique des ammonites hettangiennes du New York Canyon (Gabbs Valley Range, Nevada). Bulletin Des Laboratoires de Géologie, Minéralogie, Géophysique, 127–140. GUEX, J., AND D. G. TAYLOR. 1976. La limite Hettangien-Sinémurien, des Préalpes romandes au Nevada. Eclogae Geologicae Helvetiae, 69:521–526. GUEX, J., A. BARTOLINI, V. ATUDOREI, AND D. G. TAYLOR. 2004. High-resolution ammonite and carbon isotope stratigraphy across the Triassic-Jurassic boundary at New York Canyon (Nevada). Earth and Planetary Science Letters, 225:29–41. GUEX, J., M. RAKÚS, A. MORARD, AND M. QUARTIER-LA-TENTE. 2008. Ammonites sinémuriennes du Haut-Atlas marocain. Mémoires de Géologie, 1–118. GUGENBERGER, O. 1936a. I cefalopodi del Lias inferiore della Montagna del Casale in Provincia di Palermo (Sicilia). Palaeontographia Italica, 36:135–213. GUGENBERGER, O. 1936b. Zur Kenntnis einiger unbekannter Arten aus dem Unterlias (Bucklandi-Zone) der Provinz Palermo. Sitzungsberichte Der Akademie Der Wissenschaften in Wienmatisch-Naturwissenschaftliche Klasse. Abteilung I: Mineralogie, Biologie, Erdkunde, 47–58. HALL, R. L. 1987. New Lower Jurassic ammonite faunas from the Fernie Formation, southern Canadian Rocky Mountains. Canadian Journal of Earth Sciences, 24:1688–1704. HALL, R. L. 2006. New, biostratigraphically significant ammonites from the Jurassic Fernie Formation, southern Canadian Rocky Mountains. Canadian Journal of Earth Sciences, 43:555–570. HALLAM, A. 1965. Observations on marine Lower Jurassic stratigraphy of North America, with special reference to United States. AAPG Bulletin, 49:1485–1501. HALLAM, A. 1978. Eustatic cycles in the Jurassic. Palaeogeography, Palaeoclimatology, Palaeoecology, 23:1–32.  214  HALLAM, A. 1981. A revised sea-level curve for the Early Jurassic. Journal of the Geological Society, 138:735–743. HALLAM, A. 1987. Radiations and extinctions in relation to environmental change in the marine Lower Jurassic of northwest Europe. Paleobiology, 13:152–168. HALLAM, A. 1988. A re-evaluation of Jurassic eustasy in the light of new data and the revised Exxon curve; p. In C. K. Wilgus, B. S. Hastings, C. G. S. . Kendall, H. W. Posamatir, C. A. Ron, and J. C. van Wagner (eds.), Sea level changes: an integrated approach. SEPM Special Publication, 42, p. 261-273, Tulsa, Oklahoma. HALLAM, A. 1990. Chapter 9 Biotic and abiotic factors in the evolution of early Mesozoic marine molluscs; p. 249–260. In R. M. Ross and W. D. Allmon (eds.), Cause of Evolution: a Paleontological Perspective. University of Chicago Press, Chicago. HALLAM, A. 2001. A review of the broad pattern of Jurassic sea-level changes and their possible causes in the light of current knowledge. Palaeogeography, Palaeoclimatology, Palaeoecology, 167:23–37. HALLAM, A., AND J. M. COHEN. 1989. The case for sea-level change as a dominant causal factor in mass extinction of marine invertebrates [and discussion]. Philosophical Transactions of the Royal Society B: Biological Sciences, 325:437–455. HALLAM, A., AND P. B. WIGNALL. 1999. Mass extinctions and sea-level changes. Earth-Science Reviews, 48:217–250. HAQ, B. U., J. HARDENBOL, AND P. R. VAIL. 1987. Chronology of fluctuating sea levels since the Triassic. Science, 235:1156–1167. HAQ, B. U., J. HARDENBOL, AND P. R. VAIL. 1988. Mesozoic and Cenozoic chronostratigraphy and cycles of sea-level change; p. 71–108. In C. K. Wilgus, C. G. S. C. Hastings, C. A. Kendall, and J. C. van Wagoner (eds.), Sea level changes: an integrated approach. SEPM Special Publication, 42, Tulsa, Oklahoma. EL HARRIRI, K., J.-L. DOMMERGUES, C. MEISTER, AND D. CHAFIKI. 2010. Nouvelles données sur les ammonites du Sinémurien et du Pliensbachien basal du Haut Atlas central (Maroc). Taxonomie et implications stratigraphiques et paléobiogéographiques. Revue de Paléobiologie, 29:217–260. EL HARRIRI, K., J.-L. DOMMERGUES, C. MEISTER, A. SOUHEL, AND D. CHAFIKI. 1996. Les ammonites due lias supérieur et moyen du Haut-Atlas de Béni-Mellal (Maroc): Taxinomie et biostratigraphie à haute résolution. Geobios, 29:537–576.  215  HAUER, F. R. VON. 1856. Über Die Cephalopoden Aus Dem Lias Der Nordöstlichen Alpen. Denkschriften der Mathematisch-Naturwissenschaftlichen Classe der Kaiserlichen Akademie der Wissenschaften, Wien, 86 p. HESSELBO, S. P., D. R. GRÖCKE, H. C. JENKYNS, C. J. BJERRUM, P. FARRIMOND, H. S. MORGANS-BELL, AND O. R. GREEN. 2000. Massive dissociation of gas hydrate during a Jurassic oceanic anoxic event. Nature, 406:392–395. VON HILLEBRANDT, A. 1973. Neue ergebnisse über den Jura in Chile und Argentinien. Münster Forschung Für Geologie Und Paläontologie, 31/32:167–199. VON HILLEBRANDT, A. 1981. Faunas de Amonites del Liasico inferior y medio (Hettangiano hasta Pliensbachiano) de América del Sur (excluyendo Argentina). Cuncas Sedimentarias del Jurasico y Cretacico de América del Sur, 499–538. VON HILLEBRANDT, A. 2002. Ammoniten aus dem oberen Sinemurium von Südamerika. Revue de Paléobiologie, 21:35–147. HOFFMANN, R. 2010. New insights on the phylogeny of the Lytoceratoidea (Ammonitina) from the septal lobe and its functional interpretation. Revue de Paléobiologie, 29:1–156. HOLLAND, S. M. 2012. Sea level change and the area of shallow-marine habitat: implications for marine biodiversity. Paleobiology, 38:205–217. HOLLINGWORTH, N. T. J., D. J. WARD, M. SIMMS, AND P. CLOTHIER. 1990. A temporary exposure of Lower Lias Late Sinemurian at Dimmer Camp, Castle Cary, Somerset, south-west England. Mesozoic Research, 2:163–180. HOWARTH, M. K. 2002. The Lower Lias of Robin Hood’s Bay, Yorkshire, and the work of Leslie Bairstow. Bulletin of the Natural History Museum, Geology Series, 58:81–168. HOWARTH, M. K. 2013. Chapter 4: Psiloceratoidea, Eodoceratoidea, Hildoceratoidea; p. 1–139. In Treatise Online No.57 Part L,Revised, Volume 3B. Vol. 3. Paleontological Institute, The University of Kansas, Lawrence. HUG, O. 1899. Beiträge zur Kenntnis der Lias-und Dogger-Ammoniten aus der Zone der Freiburger Alpen, II, Die Unter-und-Mittelliasische-Ammoniten-Fauna von Blumenstein-Allmend und Langeneckgrat am Stockhorn. Abhandlungen Der Schweizerischen Paläontologischen Gesellschaf, 26:7–12.  216  HYATT, A. 1867. The fossil Cephalopoda of the Museum of Comparative Zoology. Bulletin of the Museum of Comparative Zoology, 5:71–102. HYATT, A. 1889. Genesis of the Arietidae. Smithsonian Institution & Museum of Comparative Zoology, Washington D.C.; Cambridge, 238 p. IMLAY, R. W. 1971. Jurassic ammonite succession in the United States. Colloque Du Jurassique, Luxembourg 1967, Mémorial B.G.R.M. Fr., 709–724. IMLAY, R. W. 1981. Early Jurassic ammonites from Alaska. US Geological Survey Professional Paper 1148, 1–84. IMMENHAUSER, A. 2007. High-rate sea-level change during the Mesozoic: new approaches to an old problem. Sedimentary Geology, 175:277–296. ISLAS, D. A., C. E. MACÍAS, AND K. FLORES–CASTRO. 2009. Amonoideos y bivalvos del Sinemuriano Superior en un nuevo afloramiento de la Formación Huayacocotla, Hidalgo, México, algunas consideraciones paleoambientales. Boletín de La Sociedad Geológica Mexicana, 61:185–197. JAKOBS, G. K., P. L. SMITH, AND H. W. TIPPER. 1994. An ammonite zonation for the Toarcian (Lower Jurassic) of the North American Cordillera. Canadian Journal of Earth Sciences, 31:919–942. JAWORSKI, E. 1931. Über Arnioceras geometricum OPPEL und verwandte Spezies; nebt einem Anhang über Ammonites natrix SCHLOTHEM, 1820. Neues Jahrbuch Für Mineralogie, Geologie und Paläontologie, 65:83–140. JENKYNS, H. C. 1988. The early Toarcian (Jurassic) anoxic event; stratigraphic, sedimentary and geochemical evidence. American Journal of Science, 288:101–151. JENKYNS, H. C. 2010. Geochemistry of oceanic anoxic events. Geochemistry, Geophysics, Geosystems, 11:Q03004. JENKYNS, H. C., AND G. P. WEEDON. 2013. Chemostratigraphy (CaCO3, TOC, δ13Corg) of Sinemurian (Lower Jurassic) black shales from the Wessex Basin, Dorset and palaeoenvironmental implications. Newsletters on Stratigraphy, 46:1–21. JENKYNS, H. C., C. E. JONES, D. R. GRÖCKE, S. P. HESSELBO, AND D. N. PARKINSON. 2002. Chemos tratigraphy of the Jurassic System: applications, limitations and implications for palaeoceanography. Journal of the Geological Society, 159:351–378.  217  JOHANNSON, G. G., P. L. SMITH, AND S. P. GORDEY. 1997. Early Jurassic evolution of the northern Stikinian arc: evidence from the Laberge Group, northwestern British Columbia. Canadian Journal of Earth Sciences, 34:1030–1057. KORTE, C., AND S. P. HESSELBO. 2011. Shallow marine carbon and oxygen isotope and elemental records indicate icehouse‐greenhouse cycles during the Early Jurassic. Paleoceanography, 26:PA4219. KOVÁCS, L. 1942. Monographie der liassischen Ammoniten des nördlichen Bakony. Geologica Hungarica. Series Palaeontologica 17, 1–220. KRISHNA, J., D. B. PATHAK, B. PANDEY, AND J. R. OJHA. 2000. Transgressive sediment intervals in the Late Jurassic of Kachchh, India. Advances in Jurassic Research. Proceedings of the Fifth International Symposium on the Jurassic System, 6:321–222. KURODA, J., R. S. HORI, K. SUZUKI, D. R. GRÖCKE, AND N. OHKOUCHI. 2010. Marine osmium isotope record across the Triassic-Jurassic boundary from a Pacific pelagic site. Geology, 38:1095–1098. KÜSPERT, W. 1982. Environmental changes during oil shale deposition as deduced from stable isotope ratios; p. 482–501. In G. Einsele and A. Seilacher (eds.), Cyclic and Event Stratification. Springer, Berlin. LACHKAR, N., J.-L. DOMMERGUES, C. MEISTER, P. NEIGE, A. IZART, AND J. LANG. 1998. Les ammonites du Sinémuriensupérieur du Jebel-Bou-Hamid (Haut-Atlas central, Rich, Maroc). Approches paléontologique et biostratigraphique. Geobios, 31:587–619. LEE, C. M. 1984. Lower Jurassic fossil assemblages at Sham Chung, New Territories, Hong Kong. Geological Society of Hong Kong Newsletter, 2:1–5. LEVASSEUR, S., J.-L. BIRCK, AND C. J. ALLÈGRE. 1998. Direct measurement of femtomoles of osmium and the 187Os/186Os ratio in seawater. Science, 282:272–274. LIANG, B. 1994. A Lower Jurassic Amonite Image Database and Its Applications. PhD Thesis. University of British Columbia, 426 p. LIANG, B., AND P. L. SMITH. 1997. The Jurassic ammonite image database AMMON. Palaeontology, 40:99–112. LONGRIDGE, L. M., P. L. SMITH, AND H. W. TIPPER. 2006. The Early Jurassic ammonite Badouxia from British Columbia, Canada. Palaeontology, 49:795–816.  218  LOUGHMAN, D. L., AND A. HALLAM. 1982. A facies analysis of the Pucara Group (Norian to Toarcian carbonates, organic-rich shale and phosphate) of central and northern Peru. Sedimentary Geology, 32:161–194. LUDWIG, K. R. 1980. Calculation of uncertainties of U-Pb isotope data. Earth and Planetary Science Letters, 46:212–220. MACCHIONI, F., P. L. SMITH, AND H. W. TIPPER. 2005. A new Early Sinemurian (Jurassic) ammonite species from the Taseko Lakes map area, British Columbia, Canada. Journal of Paleontology, 79:790–795. MACCHIONI, F., P. L. SMITH, AND H. W. TIPPER. 2006. Late Early Sinemurian (Early Jurassic) ammonites from the Taseko Lakes map area, British Columbia. Palaeontology, 49:557–583. MAHONEY, J. B., C. J. HICKSON, J. W. HAGGART, P. SCHIARIZZA, P. B. READ, R. J. ENKIN, P. VAN DER HEYDEN, AND S. ISRAEL. 2013. Geology, Taseko Lakes, British Columbia (maps). Geological Survey of Canada, Open File 6150, scale 1:250,000. MANDL, G. W., A. DULAI, J. SCHLÖGL, M. SIBLÍK, J. SZABÓ, I. SZENTE, AND A. VÖRÖS. 2010. First results on stratigraphy and faunal content of the Jurassic between Bad Mitterndorf and Toplitzsee (Salzkammergut, Austria). Abhandlungen Der Geologischen Bundesanstalt, 65:77–134. MATTHEWS, S. C. 1973. Notes on open nomenclature and on synonymy lists. Palaeontology, 16:713–719. MAUBEUGE, P. L. 1998. Observations et études géologiques sur le Lias inférieur du Luxembourg belge et du Grand Duché de Luxembourg. Bulletin Des Académie et Société Lorraines Des Sciences, 37:11–63. MCARTHUR, J. M., T. J. ALGEO, B. VAN DE SCHOOTBRUGGE, Q. LI, AND R. J. HOWARTH. 2008. Basinal restriction, black shales, Re-Os dating, and the Early Toarcian (Jurassic) oceanic anoxic event. Paleoceanography, 23:1–22. MCROBERTS, C. A., AND M. ABERHAN. 1997. Marine diversity and sea-level changes: numerical tests for association using Early Jurassic bivalves. Geologische Rundschau, 86:160–167. MEISTER, C. 2010. Worldwide ammonite correlation at the Pliensbachian Stage and Substage boundaries (Lower Jurassic). Stratigraphy, 7:83–101.  219  MEISTER, C., AND B. LOUP. 1989. Les gisements d’ammonites liasiques (Hettangien à Pliensbachian) du Ferdenrothorn (Valais, Suisse): analyses paléontologiques, biostratigraphiques et aspects lithostratigraphiques. Eclogae Geologicae Helvetiae, 82:1003–1041. MEISTER, C., AND J. G. FRIEBE. 2003. Austroalpine Liassic ammonites from Vorarlberg (Austria, Northern Calcareous Alps). Beiträge Zur Paläontologie, 28:9–99. MEISTER, C., AND J. SCHLÖGL. 2013. Sinemurian ammonites from Male Karpaty Mts, Western Carpathians, Slovakia. Part 2: Arietitinae (except Arnioceras). Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen, 268:1–63. MEISTER, C., V. KHUC, AND D. TRAN-HUYEN. 2004. Les ammonites du Jurassique inférieur des provinces de Dak Lak et de Hô Chi Minh Ville, Viêt Nam du Sud. Revue de Paléobiologie, Genève, 21:439–483. MEISTER, C., P. MAURIZOT, AND J. A. GRANT-MACKIE. 2010. Early Jurassic (Hettangian - Sinemurian) ammonites from New Caledonia (French Overseas Territory, western Pacific). Paleontological Research, 14:85–118. MEISTER, C., J. SCHLÖGL, AND M. RAKÚS. 2011. Sinemurian ammonites from Male Karpaty Mts., Western Carpathians, Slovakia. Part 1: Phylloceratoidea, Lytoceratoidea, Schlotheimiidae. Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen, 259:25–88. MEISTER, C., G. LAFAURIE, AND A. MARSHAL. 2012. Les ammonites du Sinémurien supérieur et du Pliensbachien basal dans les Causses (Lot, Aveyron, Lozère), France. Revue de Paléobiologie, 31:347–423. MEISTER, C., V. KHUC, D. TRAN-HUYEN, AND P. DOYLE. 2000. Les ammonites et les bélemnitesdu Jurassique inférieur de Huu Niên, province de Quang Nam, Viêt Nam Central. Geobios, 33:79–96. MEISTER, C., J. BLAU, R. SCHLATTER, AND R. SCHMIDT-EFFING. 2002. Ammonites from the Lower Jurassic (Sinemurian) of Tenango de Doria (Sierra Madre Oriental, Mexico). Part II: Phylloceratoidea, Lytoceratoidea, Schlotheimiidae, Arietitinae, Oxynoticeratidae, and Eoderoceratidae. Revue de Paléobiologie, 21:391–409. MEISTER, C., J. BLAU, J.-L. DOMMERGUES, R. SCHLATTER, AND R. SCHMIDT-EFFING. 2009. The Upper Sinemurian ammonite succession in the Sierra Madre Oriental (Mexico). Volumina Jurassica, 7:31–36.  220  MEISTER, C., J. BLAU, J.-L. DOMMERGUES, R. SCHLATTER, R. SCHMIDT-EFFING, AND K. BURK. 2005. Ammonites from the Lower Jurassic (Sinemurian) of Tenango de Doria (Sierra Madre Oriental, Mexico). Part IV : Biostratigraphy, palaeobiogeography and taxonomic addendum. Revue de Paléobiologie, 24:365–384. MELEDINA, S. V, B. N. SHURYGIN, AND O. S. DZYUBA. 2005. Stages in development of mollusks, paleobiogeography of Boreal seas in the Early-Middle Jurassic and zonal scales of Siberia. Russian Geology and Geophysics, 46:239–255. MERGEN, P. 1984. Données nouvelles et mise au point stratigraphique sur le Sinémurien en Lorraine belge. Annales de La Société Géologique de Belgique, Publications Spéciales & Mémoires, 4:109–116. MONGER, J. W. H. 2011. An overview of the tectonic history of the southern Coast Mountains, British Columbia. Canadian Paleontology Conference, Field Trip Guidebook, 16:1–11. MONGER, J. W. H., AND W. J. NOKLEBERG. 1996. Evolution of the northern North American Cordillera: generation, fragmentation, displacement and accretion of successive North American plate-margin arcs. Geology and Ore Deposits of the American Cordillera: Geological Society of Nevada Symposium Proceedings, 1133–1152. MULLER, S. W., AND H. G. FERGUSON. 1939. Mesozoic stratigraphy of the Hawthorne and Tonopah quadrangles, Nevada. Geological Society of America Bulletin, 50:1573–1624. NAU, P. S. 1984. Notes on ammonites (Arietitidae) from Sham Chung, Tolo Channel. Geological Society of Hong Kong Newsletter, 2:6–8. O’BRIEN, J. A. 1985. Biostratigraphy of the Lower Jurassic (Sinemurian) Tyaughton Group, Taseko Lakes Map Area, South Central British Columbia. BSc Thesis. University of British Columbia, 50 p. O’DOGHERTY, L., J. SANDOVAL, AND J. A. VERA. 2000. Ammonite faunal turnover tracing sea-level changes during the Jurassic (Betic Cordillera , southern Spain). Journal of the Geological Society, 157:723–736. OLDOW, J. S. 1984. Evolution of a late Mesozoic back-arc fold and thrust belt, northwestern Great Basin, USA. Tectonophysics, 102:245–274. OXBURGH, R. 1998. Variations in the osmium isotope composition of sea water over the past 200,000 years. Earth and Planetary Science Letters, 159:183–191.  221  PAGE, K. N. 2003. The Lower Jurassic of Europe: its subdivision and correlation. Geological Survey of Denmark and Greenland Bullentin, 1:23–59. PÁLFY, J. 1991. Uppermost Hettangian to Lowermost Pliensbachian (Lower Jurassic) Biostratigraphy and Ammonoid Fauna of the Queen Charlotte Islands, British Columbia. MSc Thesis. University of British Columbia, 243 p. PÁLFY, J., P. L. SMITH, AND H. W. TIPPER. 1994. Sinemurian (Lower Jurassic) ammonoid biostratigraphy of the Queen Charlotte Islands, western Canada. Geobios, 23:385–393. PÁLFY, J., P. L. SMITH, AND J. K. MORTENSEN. 2000. A U-Pb and 40Ar/39Ar time scale for the Jurassic. Canadian Journal of Earth Sciences, 37:923–944. PALMER, C. P. 1972. The Lower Lias (Lower Jurassic) between Watchet and Lilstock in north Somerset (United Kingdom). Newsletters on Stratigraphy, 2:1–30. PALMER, M. R., K. K. FALKNER, K. K. TUREKIAN, AND S. E. CALVERT. 1988. Sources of osmium isotopes in manganese nodules. Geochimica et Cosmochimica Acta, 52:1197–1202. PARONA, C. F. 1896. Contribuzionne alla conoscenza della Ammoniti Liasiche di Lombardia. Parte I: Ammoniti del Lias inferiore del Saltrio. Mémoires de La Société Paléontologique Suisse, 23:1–45. PEUCKER-EHRENBRINK, B., AND G. RAVIZZA. 2000. The marine osmium isotope record. Terra Nova, 12:205–219. PEUCKER-EHRENBRINK, B., AND B. JAHN. 2001. Rhenium-osmium isotope systematics and platinum group element concentrations: loess and the upper continental crust. Geochemistry, Geophysics, Geosystems, 2:1061–1083. PINNA, G. 1985. Exceptional preservation in the Jurassic of Osteno. Philosophical Transactions of the Royal Society of London Series B, Biological Sciences, 311:171–180. POMPECKJ, J. F. 1901. Über Tmaegoceras Hyatt. Neues Jahrbuch Für Mineralogie, Geologie Und Paläontologie, 158–170. PORTER, S. J., D. SELBY, K. SUZUKI, AND D. GRÖCKE. 2013. Opening of a trans-Pangaean marine corridor during the Early Jurassic: insights from osmium isotopes across the  222  Sinemurian-Pliensbachian GSSP, Robin Hood’s Bay, UK. Palaeogeography, Palaeoclimatology, Palaeoecology, 375:50–58. POULTON, T. P. 1991. Hettangian through Aalenian (Jurassic) guide fossils and biostratigraphy, northern Yukon and adjacent Northwest Territories. Geological Survey of Canada, Bulletin, 410:1–95. PRINZ, P. 1985. Stratigraphie und Ammonitenfauna der Pucara-Gruppe (Obertrias-Unterjura) von Nord-Peru. Palaeontographica Abteilung A Band A188 Lieferung 4-6, 153–197. QUINZIO-SINN, L. A. 1987. Stratigraphische Untersuchungen im Unterjura des Südteils der Provinz Antofagasta in Nord-Chile. Berliner Geowissenschaftliche Abhandlungen / A, Reihe A, Geologie Und Paläontologie, Band 87, 1–111. RADLEY, J. D. 2002. The Late Triassic and Early Jurassic succession at Southam Cement Works, Warwickshire. 15:171–174. RAKÚS, M. 1994. Les ammonites Lotharingiennes du Jebel Bou Hamid (Haut-Atlas de Rich, Maroc). Palaeopelagos Special Publication, 1:299–316. RAKÚS, M. 1999. Some hitherto undescribed Liassic ammonites from the Adnet Formation in Austria. Abhandlungen Der Geologischen Bundesanstalt, Wien, 56:319–328. RAKÚS, M., AND J. GUEX. 2002. Les ammonites du Jurassique inférieur et moyen de la dorsale tunisienne. Mémoires de Géologie, 39:1–217. RAVIZZA, G., AND B. PEUCKER-EHRENBRINK. 2003. Chemostratigraphic evidence of Deccan volcanism from the marine osmium isotope record. Science, 302:1392–1395. REISDORF, A. G., A. WETZEL, R. SCHLATTER, AND P. JORDAN. 2011. The Staffelegg Formation: a new stratigraphic scheme for the Early Jurassic of northern Switzerland. Swiss Journal of Geosciences, 104:97–146. REYMENT, R. A. 1959. On liassic ammonites from Skåne, southern Sweden. Stockholm Contributions in Geology, 2:103–157. REYNÈS, P. 1879. Monographie Des Ammonites, 1re Partie Lias. J.-B. Baillière, Marseille & Paris, 72 p.  223  RICCARDI, A. C. 1992. Central and northern Chile; p. 141–146. In G. E. G. Westermann (ed.), The Jurassic of the Circum-Pacific (World and Regional Geology 3). Cambridge University Press, Cambridge, UK; New York, USA; Victoria, Australia. RICCARDI, A. C., S. E. DAMBORENEA, AND M. O. MANCEÑIDO. 1990. Lower Jurassic of South America and Antarctic Peninsula. Newsletters on Stratigraphy, 21:75–103. RICCARDI, A. C., S. E. DAMBORENEA, M. O. MANCEÑIDO, AND S. C. BALLENT. 1991. Hettangian and Sinemurian (Lower Jurassic) biostratigraphy of Argentina. Journal of South American Earth Sciences, 4:159–170. RIDING, J. B., M. J. LENG, S. KENDER, S. P. HESSELBO, AND S. FEIST-BURKHARDT. 2013. Isotopic and palynological evidence for a new Early Jurassic environmental perturbation. Palaeogeography, Palaeoclimatology, Palaeoecology, 374:16–27. RUBAN, D. A. 2007. Jurassic transgressions and regressions in the Caucasus (northern Neotethys Ocean) and their influences on the marine biodiversity. Palaeogeography, Palaeoclimatology, Palaeoecology, 251:422–436. RUSMORE, M. E. 1987. Geology of the Cadwallader Group and the Intermontane-Insular superterrane boundary, southwestern British Columbia. Canadian Journal of Earth Sciences, 24:2279–2291. SANBORD, A. F. 1960. Geology and paleontology of the southwest quarter of the Big Bend quadrangle, Shasta County, California. California Division of Mines and Geology. Special Report No.63, 1–26. SANDOVAL, J., L. O’DOGHERTY, AND J. GUEX. 2001. Evolutionary rates of Jurassic ammonites in relation to sea-level fluctuations. Palaios, 16:311–335. SATO, T. 1992. Southeast Asia and Japan; p. 194–213. In G. E. G. Westermann (ed.), The Jurassic of the Circum-Pacific (World and Regional Geology 3). Cambridge University Press, Cambridge,UK; New York, USA; Victoria, Australia. SATO, T., AND G. E. G. WESTERMANN. 1991. Japan and South-East Asia. Jurassic Taxa Ranges and Correlation Charts for the Circum-Pacific. Newsletters on Stratigraphy, 24, 81–108. SCHIARIZZA, P., R. G. GABA, J. K. GLOVER, J. J. GARVER, AND P. J. UMHOEFER. 1997. Geology and mineral occurrences of the Taseko-Bridge River area. British Columbia Geological Survey Bulletin, 100:1–292.  224  SCHLATTER, R. 1984. Zur systematischen Stellung der Gattung Epophioceras SPATH (Ammonoidea). Jahresberichte Und Mitteilungen Des Oberrheinischen Geologischen Vereins, 66:175–185. SCHLATTER, R. 1991. Biostratigraphie und Ammonitenfauna des Ober-Lotharingium und Unter-Pliensbachium im Klettgau (Kanton Schaffhausen, Schweiz) und angrenzender Gebiete. Schweizerische Palaeontologische Abhandlungen,, 113:1–113. SCHLEGELMILCH, R. 1976. Die Ammoniten Des Süddeutschen Lias: Ein Bestimmungsbuch für Fossiliensammler und Geologen. Gustav Fischer Verlag, Stuttgart; New York, 212 p. SCHMIDT, E. W. 1914. Die Arieten des unteren Lias von Harzburg (Pompeckj, J. F.: Beiträge zur Paläontologie und Stratigraphie des nordwestdeutschen Jura. III). Palaeontographica, 6:1–40. VAN DE SCHOOTBRUGGE, B., T. R. BAILEY, Y. ROSENTHAL, M. E. KATZ, D. WRIGHT, K. G. MILLER, S. FEIST-BURKHARDT, AND P. G. FALKOWSKI. 2005. Early Jurassic climate change and the radiation of organic-walled phytoplankton in the Tethys Ocean. Palaeobiology, 31:147–159. SCHWAB, V. F., AND J. E. SPANGENBERG. 2007. Molecular and isotopic characterization of biomarkers in the Frick Swiss Jura sediments: a palaeoenvironmental reconstruction on the northern Tethys margin. Organic Geochemistry, 29:419–439. SELBY, D., AND R. A. CREASER. 2003. Re-Os geochronology of organic rich sediments: an evaluation of organic matter analysis methods. Chemical Geology, 200:225–240. SEY, I. I., Y. S. REPIN, E. E. KALACHEVA, T. M. OKUNEVA, K. V. PARAKETSOV, AND I. V. POLUBOTKO. 1992. 11. Eastern Russia; p. 225–246. In G. E. G. Westermann (ed.), The Jurassic of the Circum-Pacific (World and Regional Geology 3). Cambridge University Press, Cambridge,UK; New York, USA; Victoria, Australia. SHARMA, M., D. A. PAPANASTASSIOU, AND G. J. WASSERBURG. 1997. The concentration and isotopic composition of osmium in the oceans. Geochimica et Cosmochimica Acta, 61:3287–3299. SHURYGIN, B. N., B. L. NIKITENKO, S. V MELEDINA, O. S. DZYUBA, AND V. G. KNYAZEV. 2011. Comprehensive zonal subdivisions of Siberian Jurassic and their significance for circum-Arctic correlations. Russian Geology and Geophysics, 52:825–844.  225  SILBERLING, N. J. 1959. Pre-Tertiary stratigraphy and Upper Triassic paleontology of the Union District, Shoshone Mountains, Nevada. US Geological Survey Professional Paper, 322:1–67. SILBERLING, N. J., AND D. L. JONES. 1984. Lithotectonic terrane maps of the North American Cordillera, Part C: lithotectonic terrane maps of the western conterminous United States. US Geological Survey Open File, Report 84-523,. SMITH, P. L. 1981. Biostratigraphy and Ammonoid Fauna of the Lower Jurassic (Sinemurian, Pliensbachian and Lowest Toarcian) of Eastern Oregon and Western Nevada. PhD Thesis. McMaster University, 368 p. SMITH, P. L. 1983. The Pliensbachian ammonite Dayiceras dayiceroides and Early Jurassic paleogeography. Canadian Journal of Earth Sciences, 20:86–91. SMITH, P. L. 1986. The implications of data base management systems to paleontology: a discussion of Jurassic ammonoid data. Journal of Paleontology, 60:327–340. SMITH, P. L., AND H. W. TIPPER. 2000. The schlotheimiid succession across the Hettangian-Sinemurian boundary (Lower Jurassic), Taseko Lakes map area, British Columbia, Canada. Revue de Paléobiologie, Spécial Volume, 1–12. SMITH, P. L., H. W. TIPPER, D. G. TAYLOR, AND J. GUEX. 1988. An ammonite zonation for the Lower Jurassic of Canada and the United States: the Pliensbachian. Canadian Journal of Earth Sciences, 25:1503–1523. SMITH, P. L., J. W. H. MONGER, A. ARTHUR, T. P. POULTON, AND H. W. TIPPER. 1998. Southwestern British Columbia; p. 275–278. In P. L. Smith (ed.), Field Guide for the Fifth International Symposium on the Jurassic System. International Union of Geological Sciences. SOWERBY, J. DE C. 1815. The Mineral Conchology of Great Britain; or Coloured Figures and Descriptions of Those Remains of Testaceous Animals or Shells, Which Have Been Preserved at Various Times and Depths in the Earth. Volume 1, Part 17. B. Meredith, London, 203–218 p. SOWERBY, J. DE C. 1817. The Mineral Conchology of Great Britain; or Coloured Figures and Descriptions of Those Remains of Testaceous Animals or Shells, Which Have Been Preserved at Various Times and Depths in the Earth. Volume 2, Part 29. B. Meredith, London, 141–154 p.  226  SOWERBY, J. DE C. 1818. The Mineral Conchology of Great Britain; or Coloured Figures and Descriptions of Those Remains of Testaceous Animals or Shells, Which Have Been Preserved at Various Times and Depths in the Earth. Volume 3. B. Meredith, London, 1–194 p. SOWERBY, J. DE C. 1824. The Mineral Conchology of Great Britain; or Coloured Figures and Descriptions of Those Remains of Testaceous Animals or Shells, Which Have Been Preserved at Various Times and Depths in the Earth. Volume 5, Parts 77-78. B. Meredith, London, 338–648 p. SPALLETTI, L. A., H. PARENT, G. D. VEIGA, AND E. SCHWARZ. 2012. Ammonites and biostratigraphy of the Cuyo Group in the Sierra de Reyes (central Neuquén Basin, Argentina) and their sequential significance. Andean Geology, 39:464–481. SPATH, L. F. 1922a. Shales-with-Beef, a sequence in the Lower Lias of the Dorset Coast. Part 2: Notes on the ammonites. Proceedings of the Geological Society of London, Abstract, 1079:30. SPATH, L. F. 1922b. On Lower Lias ammonites from Skye. Geological Magazine, 59:170–176. SPATH, L. F. 1923. The Ammonites of the Shales-with-Beef. Quarterly Journal of the Geological Society, 79:66–88. SPATH, L. F. 1924. The ammonites of the Blue Lias. Proceedings of the Geologists’ Association, 35:186–211. SPATH, L. F. 1956. The liassic ammonite faunas of the stowell park borehole. Bulletin of the Geological Survey of Great Britain, 11:140–164. SPEED, R. C. 1979. Collided Paleozoic microplate in the western United States. The Journal of Geology, 87:279–292. STANLEY, K. O. 1971. Tectonic and sedimentologic history of Lower Jurassic Sunrise and Dunlap formations, west-central Nevada. AAPG Bulletin, 3:454–477. STEFANI, C. DE. 1887. Lias inferiore ad Arieti dell’Appennino septentrionale. Atti Della Società Toscana Di Scienze Naturali, 8:9–76. STEVENS, G. R. 2004. Hettangian-Sinemurian (Early Jurassic) ammonites of New Zealand. Monograph of the Institute of Geological and Nuclear Sciences,Wellington, New Zealand, 23:1–107.  227  STEVENS, G. R. 2012. The Early Jurassic of New Zealand: refinements of the ammonite biostratigraphy and palaeobiogeography. Revue de Paléobiologie, 11:187–204. SUESS, E. 1906. The Face of the Earth,volume 2 (Das Antlitz Der Erde) (W. J. Sollas and H. B. C. Sollas (eds.)). Clarendon Press, Oxford, 604 p. SUKAMTO, R., AND G. E. G. WESTERMANN. 1992. Indonesia and Papua New Guinea; p. 181–193. In G. E. G. Westermann (ed.), The Jurassic of the Circum-Pacific (World and Regional Geology 3). Cambridge University Press, Cambridge,UK; New York, USA; Victoria, Australia. SUN, Y., G. ZHU, G. LIU, AND H. SHENG. 1980. Studies on Lower Jurassic ammonites from Kaiping-Enping area, Guangdong. Acta Palaeontologica Sinica, 19:68–76. SUZUKI, H., P. PRINZ-GRIMM, AND R. SCHMIDT-EFFING. 2002. Radiolarien aus dem Grenzbereich Hettangium/Sinemurium von Nordperu. Paläontologische Zeitschrift, 76:163–187. TAYLOR, D. G. 1982. Jurassic shallow marine invertebrate depth zones, with exemplification from the Snowshoe Formation, Oregon. Oregon Geology, 44:51–56. TAYLOR, D. G. 1998. Late Hettangian-Early Sinemurian (Jurassic) ammonite biochronology of the Western Cordillera, United States. Geobios, 31:467–497. TAYLOR, D. G., AND P. L. SMITH. 1992. Nevada; p. 77–83. In G. E. G. Westermann (ed.), The Jurassic of the Circum-Pacific (World and Regional Geology 3). Cambridge University Press, Cambridge,UK; New York, USA; Victoria, Australia. TAYLOR, D. G., J. GUEX, AND M. RAKÚS. 2001. Hettangian and Sinemurian ammonoid zonation for the western Cordillera of North America. Bulletin de La Société Vaudoise Des Sciences Naturelles, 87:381–421. TAYLOR, D. G., P. L. SMITH, R. A. LAWS, AND J. GUEX. 1983. The stratigraphy and biofacies trends of the Lower Mesozoic Gabbs and Sunrise formations, west-central Nevada. Canadian Journal of Earth Sciences, 20:1598–1608. THEVENIN, A. 1907. Types du Prodrome de paléontologie stratigraphique universelle d’Alcide d'Orbigny. Annales de Paléontologie, 2:89–96. THOMSON, M. R. A., AND T. H. TRANTER. 1986. Early Jurassic fossils from central Alexander Island and their geological setting. British Antarctic Survey Bulletin, 70:23–99.  228  TIBULEAC, P. 2005. New data about the age and the stratigraphical position in the Cretaceous Wildflish of the Olistolith from Pasca Peak (Rarau Syncline, eastern Carpathians, Romania). Acata Palaeontologica Romaniae, 5:483–491. TIBULEAC, P. 2008. Presence of big size ammonites in the Jurassic olstoliths of Transylvanian Nappe(s) from Rarau Syncline (eastern Carpathians, Romania). Acata Palaeontologica Romaniae, 6:365–374. TILMANN, N. 1917. Die Fauna des unteren und mittleren Lias in Nord-und Mittel-Peru. Neues Jahrbuch Für Mineralogie Geologie Und Paläontologie Stuttgart Beil, 41:628–712. TIPPER, H. W. 1963. Takeko Lakes, British Columbia. Geological Survey of Canada, Map 29-1963, Scale 1:250000,. TIPPER, H. W. 1978. Taseko Lakes map area (92-O). Geological Survey of Canada, Open File 534, Scale 1:250000,. TOMAS, R., AND J. PÁLFY. 2007. Revision of Early Jurassic ammonoid types from the Perşani Mts. (East Carpathians, Romania). Neues Jahrbuch Für Geologie Und Paläontologie Abhandlungen, 243:231–254. TOPCHISHVILI, M. 1998. Caracterización bioestratigráfica de los materiales del Jurásico Inferior de Georgia por medio de ammonites. Cuadernos de Geología Ibérica, 277–291. TRUEMAN, A. E., AND D. M. WILLIAMS. 1927. Notes on some Lias ammonites from the Cheltenham District. Proceedings of the Cotteswold Naturalists’ Field Club, Gloucester, 22:239–253. UMHOEFER, P. J. 1990. Stratigraphy and tectonic setting of the upper part of the Cadwallader terrane, southwestern British Columbia. Canadian Journal of Earth Sciences, 27:702–711. UMHOEFER, P. J., AND P. SCHIARIZZA. 1993. Timing and offset on strike-slip faults in the SE Coast Belt, B.C. and Washington and 40-80 Ma fault reconstructions. Geological Society of America, Abstracts with Progarms, 25:156. UMHOEFER, P. J., AND H. W. TIPPER. 1998. Stratigraphy, depositional environment and tectonic setting of the Upper Trassic to Middle Jurassic rocks of the Chilcotin Ranges, southwestern British Columbia. Geological Survey of Canada, Bulletin 519, 1–58.  229  UMHOEFER, P. J., J. J. GARVER, AND H. W. TIPPER. 1988. Geology of the Relay Mountain area (92O/2, 93O/3). British Columbia Ministry of Energy, Mines and Petroleum Resources, Open File Map 1988-16, 1:20000,. VAIL, P. R., AND R. G. TODD. 1981. Northern North Sea Jurassic unconformities, chronostratigraphy and sea-level changes from seismic stratigraphy; p. 216–235. In L. V Illing and G. Hobson (eds.), Petroleum Geology of the Continental Shelf of North-West Europe. Heydon,London. VENTURI, F., AND R. FERRI. 2001. Ammoniti Liassici dell’Appennino Centrale, 3rd ed. Citta di Castello, Perugia, Italy, 271 p. VENTURI, F., AND C. NANNARONE. 2002. Ammoniti del Sinemuriano inferiore del Monte Cetona (Prov. di Siena). Bollettino Della Societa Paleontologica Italiana, 41:131–162. VENTURI, F., M. BILOTTA, AND C. RICCI. 2006. Comparison between western Tethys and eastern Pacific ammonites: further evidence for a possible late Sinemurian-early Pliensbachian trans-Pangaean marine connection. Geological Magazine, 143:699–711. VERA, J. A. 1988. Evolución de los sistemas de depósito en el margen ibérico de la Cordillera Bética. Revista de La Sociedad Geológica de España, 1:373–391. VIALLI, V. 1959. Ammoniti Sinemuriane del Monte Albenza (Bergamo). Memorie Della Società Italiana Di Scienze Naturali E Del Museo Civico Di Storia Naturale Di Milano, 12:144–188. VÖLKENING, J., T. WALCZYK, AND K. G. HEUMANN. 1991. Osmium isotope ratio determinations by negative thermal ionization mass spectrometry. International Journal of Mass Spectrometry and Ion Processes, 105:147–159. VAN WAGONER, J. C., R. M. MITCHUM, K. M. CAMPION, AND V. D. RAHMANIAN. 1990. Siliciclastic sequence stratigraphy in well logs, cores, and outcrops. AAPG Methods in Exploration Series, No. 7, 1–55. WANG, Y., AND G. HE. 1981. Some Early Jurassic ammonoids from Eastern Himalayas (in Chinese); p. 314–333. In Y. Shi (ed.), Qinghai-Tibet Plateu Scientific Expedition Series: Paleontology of Tibet (Section 3). Science Press, Beijing. WANG, Y., AND P. L. SMITH. 1986. Sinemurian (Early Jurassic) ammonite fauna from the Guangdong region of Southern China. Journal of Paleontology, 60:1075–1085.  230  WHEELER, J. O., AND P. MCFEELY. 1991. Tectonic Assemblage Map of the Canadian Cordillera and adjacent parts of the United States of America. Geological Survey of Canada, Map 1715A, Scale 1:2000,000. WIEDMANN, J. 1970. Über den Ursprung der Neoammonoideen: das Problems einer Typogenese. Eclogae Geologicae Helvetiae, 63:923–1020. WILLARD, B. 1963. Ontogeny of the Jurassic ammonite Arietites from Peru. Proceedings of the Pennsylvania Academy of Science, 37:211–215. WILMSEN, M., J. BLAU, C. MEISTER, M. MEHDI, AND F. NEUWEILER. 2002. Early Jurassic (Sinemurian to Toarcian) ammonites from the central High Atlas (Morocco) between Er-Rachidia and Rich. Revue de Paléobiologie, 21:149–175. YOUNG, G. M., AND J. BIRD. 1828. A Geological Survey of the Yorkshire Coast: Describing the Strata and Fossils Occuring between the Humber and the Tees, from the German Ocean to the Plain of York. Whitby, Yorkshire, 368 p.    APPENDICES  Appendix A  FOSSIL LOCALITIES  SECTION LC1  Last Creek: west of the headwaters of the creek.  Base of section: Lat. 51°05′25.58″ N, Long. 123°00′46.76″ W. Altitude: 2219 m.  Top of section: Lat. 51°05′25.83″ N, Long. 123°00′47.78″ W. Altitude: 2226 m.    Thesis Number Field Number GSC Locality Zone L1-01 LC 2012 7A  Involutum L1-02 LC 2012 2A  Involutum L1-03 LC 2012 8A  Involutum L1-04 LC 2012 3A  Involutum L1-05 LC 2012 4A  Leslei L1-06 LC 2012 5A  Leslei L1-07 LC 2012 6A  Leslei L1-08 LC 2012 9A  Leslei L1-09 LC 2012 10A  Leslei L1-10 LC 2012 11A  Leslei  SECTION LC2  Last Creek: on the cliff of the western peak near the top of the Last Creek.  Base of section: Lat. 51°05′30.67″ N, Long. 123°00′56.64″ W. Altitude: 2289 m.  Top of section: Lat. 51°05′30.23″ N, Long. 123°00′57.54″ W. Altitude: 2310 m.    Thesis Number Field Number GSC Locality Zone L2-01 LC 2012 12A  Leslei L2-02 LC 2012 13A  Leslei L2-03 LC 2012 14A  Leslei L2-04 LC 2012 15A  Leslei L2-05 LC 2012 16A  Leslei L2-06 LC 2012 17A  Leslei L2-07 LC 2012 18A  Leslei L2-08 LC 2012 19A  Leslei    SECTION FCD1  Five Card Draw: from the upper part of the Ferguson Hill Member limestone on the north side of the valley to the base of the New York Canyon Member limestone on the south side of the valley.  Base of section: Lat. 38°29′52.40″ N, Long. 118°05′38.58″ W. Altitude: 1686 m.  Top of section: Lat. 38°29′49.34″ N, Long. 118°05′35.72″ W. Altitude: 1731 m.   Thesis Number Field Number GSC Locality Zone F1-01 FCD 2012 1A  Involutum F1-02 FCD 2012 2A  Involutum F1-03 FCD 2012 3A FL  Involutum F1-04 FCD 2012 4A  Involutum F1-05 FCD 2012 11A  Involutum F1-06 FCD 2012 5A  Involutum F1-07 FCD 2012 6A FL  Involutum F1-08 FCD 2012 7A FL  Leslei F1-09 FCD 2012 8A FL  Leslei F1-10 FCD 2012 12A  Leslei F1-11 FCD 2012 13A  Leslei F1-12 FCD 2012 14A  Leslei F1-13 FCD 2012 15A  Leslei F1-14 FCD 2012 16A  Leslei F1-15 FCD 2012 17A  Leslei F1-16 FCD 2012 18A  Leslei F1-17 FCD 2012 19A  Leslei F1-18 FCD 2012 20A  Leslei F1-19 FCD 2012 21A  Leslei F1-20 FCD 2012 22A  Leslei F1-21 FCD 2012 23A  Leslei F1-22 FCD 2012 24A  Leslei F1-23 FCD 2012 25A  Leslei F1-24 FCD 2012 26A  Leslei F1-25 FCD 2012 27A  Leslei F1-26 FCD 2012 28A  Leslei F1-27 FCD 2012 9A  Carinatum F1-28 FCD 2012 29A  Carinatum F1-29 FCD 2012 30A  Carinatum F1-30 FCD 2012 10A  Carinatum F1-31 FCD 2012 31A  Carinatum F1-32 FCD 2012 33A  Carinatum F1-33 FCD 2012 32A  Carinatum F1-34 FCD 2012 34A  Carinatum F1-35 FCD 2012 FL 250  Carinatum F1-36 FCD 2012 36A  Harbledownense F1-37 FCD 2012 35A  Harbledownense   F1-38 FCD 2012 35.5A  Harbledownense  SECTION FCD2  Five Card Draw: near the head of Five Card Draw, about 300 meters east of section FCD1.  Base of section: Lat. 38°29′52.68″ N, Long. 118°05′29.25″ W. Altitude: 1725 m.  Top of section: Lat. 38°29′50.78″ N, Long. 118°05′29.17″ W. Altitude: 1762 m.   Thesis Number Field Number GSC Locality Zone 2012 2013 F2-01  FCD 1A  Carinatum F2-02  FCD 2A  Carinatum F2-03 FCD II 37A FL (011-012) FCD 3A  Carinatum F2-04 FCD II FL (013-014) FCD 4A  Carinatum F2-05 FCD II 017 IP, FL   Carinatum F2-06 FCD II 019 FL (019-020) FCD 5A  Carinatum F2-07 FCD II 021 FL FCD 6A  Carinatum F2-08  FCD 7A  Carinatum F2-09 FCD II FL 025-026   Carinatum F2-10  FCD 8A  Carinatum F2-11  FCD 9A  Carinatum F2-12  FCD 10A  Carinatum F2-13  FCD 11A  Carinatum F2-14  FCD 12A  Carinatum F2-15 FCD II 052 FL   Carinatum F2-16  FCD 13A  Carinatum F2-17 FCD II 060IP (38A) FCD 14A  Carinatum F2-18 FCD II 061 IP (39A)   Carinatum F2-19  FCD 15A  Carinatum F2-20  FCD 16A  Carinatum F2-21 FCD II 066-067   Harbledownense F2-22 FCD II 40A   Harbledownense F2-23 FCD II 079 IP   Harbledownense F2-24 FCD II 080 FL   Harbledownense F2-25  FCD 17A  Harbledownense F2-26  FCD 18A  Harbledownense  OTHER LOCALITIES  T Last Creek: all other localities not from the measured sections near and around the headwaters of Last Creek are catalogued as T in this study. The number herein are specimen numbers. Collections are from three sources: Dr. H. W. Tipper (GSC), Dr. P. L. Smith (UBC)   and Mr. W. C. Brimblecombe (Vancouver Paleontology Society). Refer to section L1 and L2 for coordinates and altitude.   Thesis Number Field Number GSC Locality Zone T 01 A8T8 No GSC #  Involutum T 02 A8T9-1  Involutum T 03-01 A8T4 C-117484 02 C-117484 Involutum T 03-02 C-117484 C-117484 Involutum T 04 A8T12 C-143323 A C-143323 Involutum T 05 A9T13 C-143328 B  Involutum T 06 Tmaeg C-143345 C-143345 Involutum T 07 A8T8 C-56472 C-56472 Involutum T 08-01 A7T6 C-62371 01 C-62371 Involutum T 08-02 A7T6 C-62371 C-62371 Involutum T 09 Tmaeg C-94839 C-94839 Involutum T 10 PLS-LC-FL  Involutum-Leslei T 11-01 A6T10 C-143330 01 C-143330 Leslei T 11-02 A6T10 C-143330 02 C-143330 Leslei T 11-03 A6T10 C-143330 03 C-143330 Leslei T 11-04 A6T10 C-143330 04 C-143330 Leslei T 11-05 A9T17 C-143330 01 C-143330 Leslei T 11-06 A9T17 C-143330 02 C-143330 Leslei T 11-07 A9T17 C-143330 03 C-143330 Leslei T 12 A7T12 C-143829 C-143829 Leslei T 13-01 A8T3 C-177626 01 C-177626 Leslei T 13-02 A8T3 C-177626 02 C-177626 Leslei T 14 A7T10 C-94240 C-94240 Leslei T 15 LC-WCB-03  Leslei T 16-01 A9T11 C-056971 01 C-056971 Harbledownense T 16-02 A9T11 C-056971 02 C-056971 Harbledownense T 16-03 A9T11 C-056971 03 C-056971 Harbledownense T 16-04 A9T11 C-056971 04 C-056971 Harbledownense  OTHER LOCALITIES   F3 Five Card Draw: all other localities not from the measured section from the Ferguson Hill Member limestone along the Five Card Draw valley between section F1 and F2, collected by Dr. P. L. Smith (UBC). The numbers herein are specimen numbers. All specimens in situ otherwise indicated.   Thesis Number Field Number GSC Locality Zone F3-01 P1-A-1    Involutum F3-02 P1-A-2    Involutum   F3-03 P1-A-3    Involutum F3-04 P1-A-4    Involutum F3-05 P1-A-5    Involutum F3-06 P1-A-6    Involutum F3-07 P1-A-7    Involutum F3-08 P1-TM-1    Involutum F3-09 P1-TM-2    Involutum F3-10 P1-TM-3    Involutum F3-11 P1-TV-1    Involutum F3-12 P1-TV-2    Involutum F3-13 P1-TV-3    Involutum F3-14 P1-TV-4    Involutum      Appendix B  AMMONITE BIODIVERSITY  LAST CREEK (GENERA)  ZONE GENERA COUNT FAD LAD DATA SOURCE Involutum Coroniceras 1   This work Fucinites 2 √ √ This work Tmaegoceras 3 √ √ This work Tipperoceras 4 √ √ This work Arnioceras 5 √  This work Arietites 6  √ Umhoefer&Tipper, 1998 Primarietites 7  √ Umhoefer&Tipper, 1998 Agassiceras 8   Umhoefer&Tipper, 1998 Vermiceras 9  √ Umhoefer&Tipper, 1998 Boucaulticeras 10   Umhoefer&Tipper, 1998 Megarietites 11   Umhoefer&Tipper, 1998 Leslei Arnioceras 1   This work Lytoceras 2   This work Ectocentrites 3 √ √ This work Caenisites 4 √ √ This work Coroniceras 5  √ Umhoefer&Tipper, 1998 Aegasteroceras 6  √ Umhoefer&Tipper, 1998 Hypasteroceras 7 √ √ Umhoefer&Tipper, 1998 Partschiceras 8   Umhoefer&Tipper, 1998 Phylloceras 9   Macchioni et al., 2006 Procliviceras 10   Macchioni et al., 2006 Nevadaphyllites 11   Macchioni et al., 2006 Togaticeras 12   Macchioni et al., 2006 Lytotropites 13   Macchioni et al., 2006 Carinatum Asteroceras 1 √ √ This work Microderoceras 2   Macchioni et al., 2006 Xipheroceras 3 √ √ Macchioni et al., 2006 Epophioceras 4 √ √ This work Harbledownense Echioceras n. gen 1 √  This work   LAST CREEK (SPECIES) ZONE GENERA SPECIES COUNT FAD LAD DATA SOURCE Involutum Coroniceras sp. 1 √ √ This work Coroniceras charlesi 2 √ √ This work Coroniceras cf. lyra 3 √ √ This work Coroniceras multicostatum 4 √ √ This work   Coroniceras cf. mutabile 5 √  This work Fucinites sicilianus 6  √ This work Tmaegoceras crassiceps 7  √ This work Tmaegoceras cf. latesulcatum 8  √ This work Tipperoceras mullerense 9 √ √ This work Tipperoceras n. sp. A 10  √ This work Coroniceras sp. 11   Umhoefer&Tipper, 1998 Arietites bisulcatum 12  √ Umhoefer&Tipper, 1998 Tmaegoceras sp. 13  √ Umhoefer&Tipper, 2000 Primarietites sp. 14   Umhoefer&Tipper, 1998 Agassiceras sp. 15   Umhoefer&Tipper, 1998 Vermiceras sp. 16  √ Umhoefer&Tipper, 1998 Boucaulticeras sp. 17   Umhoefer&Tipper, 1998 Megarietites sp. 18   Umhoefer&Tipper, 1998 Leslei Arnioceras densicosta 1 √  This work Arnioceras ceratitoides 2 √  This work Arnioceras sp. 3 √  This work Arnioceras semicostatum 4 √ √ This work Arnioceras cf. arnouldi 5 √  This work Arnioceras miserabile 6 √ √ This work Arnioceras n. sp. A 7 √ √ This work Arnioceras cf. oppeli 8 √  This work Arnioceras sp. juv. 9 √  This work Arnioceras spp. Juv 10 √  This work Lytoceras sp. 11   This work Ectocentrites leslei 12 √ √ This work Caenisites brooki 13 √ √ This work Caenisites sp. 14 √ √ This work Caenisites turneri 15 √ √ This work Coroniceras spp. 16   Umhoefer&Tipper, 1998 Aegasteroceras sp. 17   Umhoefer&Tipper, 1998 Arnioceras aff. arnouldi 18   Umhoefer&Tipper, 1998 Hypasteroceras sp. 19   Umhoefer&Tipper, 1998 Partschiceras sp. 20   Umhoefer&Tipper, 1998 Phylloceras cf. costatoradiatum 21   Macchioni et al., 2006 Procliviceras striatocostatum 22   Macchioni et al., 2006 Nevadaphyllites sp. 23   Macchioni et al., 2006 Togaticeras sp. juv. 24   Macchioni et al., 2006 Lytotropites fucinii 25   Macchioni et al., 2006 Coroniceras mutabile 26  √ Macchioni et al., 2006 Arnioceras aff. nevadanum 27   Macchioni et al., 2006 Arnioceras sp. 28   Macchioni et al., 2006 Caenisites aff. turneri 29 √ √ Macchioni et al., 2006 Caenisites pulchellus 30 √ √ Macchioni et al., 2006 Caenisites aff. pulchellus 31 √ √ Macchioni et al., 2006 Hypasteroceras montii 32   Macchioni et al., 2006 Carinatum Asteroceras cf. margarita 1 √ √ This work Asteroceras sp. 2 √ √ Macchioni et al., 2006   Microderoceras sp. 3   Macchioni et al., 2006 Xipheroceras sp. 4 √ √ Macchioni et al., 2006 Epophioceras carinatum 5 √ √ This work Harbledown-ense Echioceras n. gen n. sp. 1 √  This work   FIVE CARD DRAW (GENERA)  ZONE GENERA COUNT FAD LAD DATA SOURCE Involutum Coroniceras 1  √ This work Tmaegoceras 2 √ √ This work Tipperoceras 3 √ √ This work Arnioceras 4 √  This work Angulaticeras 5   Taylor et al., 2001 Gexiceras 6 √ √ Taylor et al., 2001 Leslei Arnioceras 1   This work Ectocentrites 2 √  This work Caenisites 3 √ √ Taylor et al., 2001 Adnethiceras 4 √ √ Taylor et al., 2001 Asteroceras 5 √  Taylor et al., 2001 Carinatum Asteroceras 1  √ This work Epophioceas 2 √ √ This work Eparietites 3 √ √ This work Arctoasteroceras 4 √ √ Taylor et al., 2001 Microderoceras 5 √ √ Taylor et al., 2001 Gleviceras 6 √  Taylor et al., 2001 Arnioceras 7  √ This work Harbledownense Oxynoticeras 1 √ √ This work Paltechioceras 2 √ √ This work Gleviceras 3  √ This work Palaeoechioceras 4 √ √ This work   FIVE CARD DRAW (SPECIES  ZONE GENERA SPECIES COUNT FAD LAD DATA SOURCE Involutum Coroniceras cf. involutum 1 √ √ This work Coroniceras cf. mutabile 2 √ √ This work Tmaegoceras obesus n. sp. 3 √ √ This work Tmaegoceras crassiceps 4 √ √ This work Tmaegoceras nudaries 5 √ √ This work Tipperoceras mullerense 6 √ √ This work   Arnioceras arnouldi 7 √  This work Arnioceras densicosta 8 √  This work Arnioceras sp. juv. 9 √  This work Arnioceras ceratitoides 10 √  This work Coroniceras fergusoni 11 √ √ Taylor et al., 2001 Coroniceras volcanoense 12 √ √ Taylor et al., 2001 Coroniceras luningense 13 √ √ Taylor et al., 2001 Angulaticeras boulcaultianum 14 √ √ Taylor et al., 2001 Gexiceras profunds 15 √ √ Taylor et al., 2001 Leslei Arnioceras arnouldi 1   This work Arnioceras ceratitoides 2   This work Arnioceras densicosta 3   This work Arnioceras sp. juv. 4  √ This work Arnioceras miserabile 5 √  This work Ectocentrites leslei 6 √  This work Arnioceras aff. arnouldi 7 √ √ Taylor et al., 2001 Arnioceras aff.crassicosta 8 √ √ Taylor et al., 2001 Arnioceras n. sp. A 9 √ √ Taylor et al., 2001 Arnioceras cf. semicostatum 10 √ √ Taylor et al., 2001 Arnioceras cf. speciosum 11 √ √ Taylor et al., 2001 Arnioceras aff. mendax 12 √ √ Taylor et al., 2001 Caenisites aff. brooki 13 √ √ Taylor et al., 2001 Adnethiceras cf. adnethicum 14 √ √ Taylor et al., 2001 Asteroceras aff.varians 15 √ √ Taylor et al., 2001 Carinatum Asteroceras sp. 1 √ √ This work Asteroceras cf. varians 2 √ √ This work Asteroceras cf. margarita 3 √ √ This work Epophioceas carinatum 4 √ √ This work Epophioceas cf. carinatum 5 √ √ This work Epophioceas sp. 6 √ √ This work Epophioceas cf. wendenlli 7 √ √ This work Eparietites ex gr. impedens 8 √ √ This work Arnioceras miserabile 9  √ This work Arnioceras arnouldi 10  √ This work Arnioceras ceratitoides 11  √ This work Arnioceras densicosta 12  √ This work Ectocentrites leslei 13  √ This work Arctoasteroceras jeletzkyi 14 √ √ Taylor et al., 2001 Microderoceras sp. 15 √ √ Taylor et al., 2001 Gleviceras chollai 16 √ √ Taylor et al., 2001 Asteroceras jamesi 17 √ √ Taylor et al., 2001 Asteroceras ocottiloi 18 √ √ Taylor et al., 2001 Asteroceras aff. varians 19 √ √ Taylor et al., 2001 Asteroceras cf. suevicum 20 √ √ Taylor et al., 2001 Asteroceras aff. confusum 21 √ √ Taylor et al., 2001 Harbledownense Oxynoticeras cf. simpsoni 1 √ √ This work Paltechioceras harbledownense 2 √  This work Paltechioceras boehmi 3 √  This work Gleviceras ex gr. victoris 4 √  This work   Palaeoechioceras cf. spirale 5 √  This work Paltechioceras mineralensis 6 √ √ Taylor et al., 2001 Gleviceras cf. subguibalianum 7 √  Taylor et al., 2001 Paltechioceras cf. rothpletzi 8 √  Taylor et al., 2001 Paltechioceras edmundi 9 √  Taylor et al., 2001      Appendix C  PUBLICATION  The article from which Chapter 5 is modified is published on Early and Planetary Science Letters by Elsevier B.V., and can be downloaded from the following link:  http://dx.doi.org/10.1016/j.epsl.2014.04.023 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
https://iiif.library.ubc.ca/presentation/dsp.24.1-0165994/manifest

Comment

Related Items