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Uppermost Hettangian to lowermost Pliensbachian (Lower Jurassic) biostratigraphy and ammonoid fauna of… Pálfy, József 1991

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UPPERMOST H E T T A N G I A N TO LOWERMOST PLIENSBACHIAN (LOWER JURASSIC) BIOSTRATIGRAPHY AND AMMONOID FAUNA OF T H E QUEEN C H A R L O T T E ISLANDS, BRITISH COLUMBIA by JOZSEF PALFY Diploma in Geology, Lorand Eotvos University, Budapest, 1986 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE F A C U L T Y OF GRADUATE STUDIES DEPARTMENT OF GEOLOGICAL SCIENCES We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA 1991 April (c) Jozsef Palfy, 1991 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of feoLpfric AL- ScietJcsS The University of British Columbia Vancouver, Canada Date APn.it- yal \*°> i DE-6 (2/88) ii A B S T R A C T Extensive fossil collections from the upper part of the Sandilands and the lowermost Ghost Creek Format ions allowed a detailed taxonomic study of the latest Hettangian to earliest Phensbachian ammonoid fauna of the Queen Charlot te Islands. 61 taxa, allocated to 27 genera, are described. Sunrisites senihlevis, Plesechioceras yakounense, Tetraspidoceras pacificum and Tetraspidoceras recognitum are introduced as new species. The vertical d is t r ibut ion of ammonites, documented in measured sections, serves as a basis to dist inguish six successive assemblage zones: the Canadensis Zone, "Coromceras" Zone, A r n o u l d i Zone, Var ians Zone, Harbledownense Zone, and Recogni tum Zone. O f these only the Canadensis Zone was established earlier, the remaining five are defined here for the first t ime. Th i s zonation permits high-resolution correlation of the sections. The total thickness of uppermost Hettangian to lowermost Pl iensbachian strata in sections on K u n g a Island is estimated at 385 m. A comparison of selected zones in different sections shows a subtle thickness increase to the south. The contact of the Sandilands Format ion and the overlying Ghost Creek Format ion is diachronous, younging gradually to the south. The faunal succession in the Queen Charlot te Islands agrees well w i th that of the Taseko Lakes area and Nevada, promising regional appl icabi l i ty of the proposed zones. Intercontinental correlation wi th the northwest European standard zonation is possible at diffrent levels. The Het tangian /S inemur ian boundary is contained wi th in the Canadensis Zone. It is best approximated by the first appearance of Badouxia columbiae and Metophioceras spp. The position of the Recogni tum Zone at the S inemur ian /Pl iensbachian boundary remains problematic; most evidence on hand points to its Pl iensbachian affinities. T h e ammonite fauna consists of taxa wi th pandemic, Te thyan , Athabascan, East Pacific, and Pacific d is t r ibut ion. Provinc ia l i sm was not prominent but existed during the Sinemurian t ime. The high proport ion of Te thyan forms is in accord wi th the theory suggesting a more southerly or iginal paleolatitude for Wrangel l ia . The dis t r ibut ion of Te thyan forms can be explained by the early opening of the Hispanic Corr idor , proven to be in existence by the Pl iensbachian. Al ternat ively , the pantropic dis t r ibut ion model cannot be ruled out, although the faunal record from the eastern Tethys is inadequate to prove i t . The strong representation of Athabascan and East Pacific elements renders long-distance longi tudinal tectonic dislocation of Wrangel l ia unlikely. The paleoecology and taphonomy of ammonites, associated macrofauna, and trace fossils is used for paleoenvironmental reconstruction. The general lack of bioturbat ion, predominance of thin-shelled, presumably pseudo-planktonic bivalves, and the intact preservation of fish and a crinoid specimen indicate prevail ing oxygen deficient bo t tom conditions. Trace fossils provide evidence for periodic improvements of bo t tom oxygenation. Different modes of ammonite preservation are controlled by shell morphology as well as the varying sedimentation rate and diagenetic regime. The latter reflects changes in redox conditions in the upper sediment layers. iv T A B L E OF CONTENTS ABSTRACT ii TABLE OF CONTENTS iv LIST OF TABLES vii LIST OF FIGURES viii LIST OF PLATES x ACKNOWLEDGEMENT xii CHAPTER 1 INTRODUCTION 1 1.1 LOCATION AND ACCESS OF THE STUDY AREA 1 1.2 PURPOSE OF STUDY 1 1.3 PREVIOUS WORK 3 1.4 METHODS 6 CHAPTER 2 GENERAL GEOLOGY 7 2.1 GEOLOGICAL SETTING OF THE QUEEN CHARLOTTE ISLANDS 7 2.2 STRATIGRAPHY 9 2.2.1 SYNOPSIS OF UPPER TRIASSIC TO LOWER JURASSIC STRATIGRAPHY 9 2.2.2 SANDILANDS FORMATION 10 2.2.3 GHOST CREEK FORMATION 12 CHAPTER 3 BIOSTRATIGRAPHY AND BIOCHRONOLOGY 13 . 3.1 INTRODUCTION 13 3.3 BIOSTRATIGRAPHY OF THE MEASURED SECTIONS 19 CHAPTER 4 PALEOBIOGEOGRAPHY 47 4.1 INTRODUCTION 47 4.2 EARLIER NORTH AMERICAN SYNTHESES 47 4.3 ASSESSMENT OF THE QUEEN CHARLOTTE ISLANDS FAUNA 48 4.4 MODELS EXPLAINING T E T H Y A N FAUNAS IN THE CORDILLERA 53 V CHAPTER 5 PALEOECOLOGY AND TAPHONOMY 55 5.1 AMMONITE PALEOECOLOGY 55 5.2 THE PRESERVATION OF AMMONITES 56 5.2.1 CASE HISTORIES 56 5.3 PALEOECOLOGY OF THE ASSOCIATED MACROFAUNA 59 5.3.1 BIVALVES 59 5.3.2 VERTEBRATES 60 5.3.3 STALKED CRINOID 60 5.4 TRACE FOSSILS 61 5.5 RESULTS 62 CHAPTER 6 SYSTEMATIC PALEONTOLOGY 63 6.1 INTRODUCTION 63 6.2 SYSTEMATIC DESCRIPTIONS 65 PhyUoceras 65 Juraphylhtes 66 Lyioceras 73 Adnethiceras 75 Tragolytoceras 77 Audaxlytoce'ras 79 Eciocentntes 81 Eolytoceras 82 Angulaticeras 86 Sulcifentes 89 Sunnsites 95 Badouxia 98 Vermiceras 108 Metophioceras 114 Coroniceras 120 v i Amioceras 122 Asteroceras 136 Hypasteroceras 142 Epophioceras 145 Plesechioceras 148 Paltechioceras 156 Oxynoticeras 163 Gleviceras 165 Radstockic eras 167 Crucilobiceras 170 Tetraspidoceras 172 Posidonotis 181 CHAPTER 7 CONCLUSIONS 184 REFERENCES 186 APPENDIX 202 PLATES 209 vii LIST OF T A B L E S Table 4-1 Tempora l pattern of genus level provincia l ism 52 Table 4-2 Tempora l pat tern of species level provincial ism 52 viii L I S T O F F I G U R E S Figure 1-1 Index map of the measured stratigraphic sections and fossil localities 2 Figure 2-1 Tectonostratigraphic terranes of the Canadian Cordi l le ra 8 Figure 2-2 Upper Triassic-Lower Jurassic l i thostrat igraphy of the Queen Char lo t te Islands 9 Figure 3-1 Zonation and relative stratigraphic ranges of the ammonite taxa 15 Figure 3-2 Sketch map of Kennecott Poin t showing the location of the measured sections 20 Figure 3-3 Legend for the lithologic columns on F i g . 3-4 to F i g . 3-13 21 Figure 3-4 Biostrat igraphy of Section D at Kennecot t Poin t 22 Figure 3-5 Biostrat igraphy of Section F at Kennecot t Po in t 23 Figure 3-6 Biostrat igraphy of Section G at Kennecot t Point . . . 24 Figure 3-7 Biostrat igraphy of Section B at Kennecott Poin t 25 Figure 3-8 Biostrat igraphy of Section H at Y a k o u n River , central G r a h a m Island 26 Figure 3-9 Biostrat igraphy of Section I at Y a k o u n River , central G r a h a m Island 28 Figure 3-10 Biostrat igraphy of Section L at Ghost M a m Roadcut , central G r a h a m Island 29 Figure 3-11 Biostrat igraphy of Section M on Maude Island 31 Figure 3-12 Biostrat igraphy of Section S on K u n g a Island 33 Figure 3-13 Biostrat igraphy of Section T on K u n g a Island 34 Figure 3-14 Biostratigraphic correlation of the measured sections 35 Figure 3-15 Lateral thickness changes of selected zones 36 Figure 3-16 Diachronism at the contact of the Sandilands and Ghost Creek Format ions 38 Figure 3-17 Approximate correlation of the proposed ammonite assemblage zones wi th the northwest European and Alp ine zonations. 39 Figure 4-1 . His togram of the number of genera wi th different dis t r ibut ion pat tern 49 Figure 4-2 His togram of the number of species wi th different dis t r ibut ion pat tern 50 Figure 4-3 Examples of species wi th different paleobiogeographic d is t r ibut ion 51 Figure 6-1 Septal suture of Juraphylhtes aff. nardn 71 Figure 6-2 Septal suture of Lytoceras sp 75 ix Figure 6-3 Cross section of the holotype of Sunrisites senililevis n . sp 96 Figure 6-4 Scatter diagram of U D vs. D M A X of Badouxia canadensis and Badouxia columbiae 100 Figure 6-5 Scatter d iagram of P R H W vs. U D of Badouxia canadensis and Badouxia columbiae 101 Figure 6-6 R ib frequency curves of Vermiceras ex gr. coregonense 112 Figure 6-7 R i b frequency diagram of Vermiceras sp 114 Figure 6-8 R ib frequency curves of Metophioceras cf. rursicostatum 117 Figure 6-9 R i b frequency curves of Metophioceras aff. rotarium 119 Figure 6-10 R ib frequency curves of Arnioceras arnouldi 124 Figure 6-11 R ib frequency curves of Arnioceras speciosum 131 Figure 6-12 R i b frequency curves of Plesechioceras yakounense n . sp 151 Figure 6-13 R ib frequency curves of Plesechioceras ? harbledownense and P. ? aklavikense 155 Figure 6-14 R i b frequency curves of Paltechioceras cf. romanicum, P. cf. rothpletzi and P. sp 158 Figure 6-15 R ib frequency curves of Paltechioceras aff. boehmi 161 Figure 6-16 Tubercle frequency cuves of Tetraspidoceras pacificum n . sp 175 Figure 6-17 P r i m a r y rib frequency of Tetraspidoceras recognitum n. sp 178 L I S T O F P L A T E S x Plate 1 Juraphyllites cf. transylvaniens , Juraphyllites aff. nardii , Phylloceras sp., Juraphyllites cf. hmatus, Juraphyllites sp., Lytoceras spp., Lytoceras sp 211 P L A T E 2 Ectocentrites ? sp., Tragolytoceras ? sp., Eolytoceras ? guexi ?, Adnethiceras cf. adnethicum, Audaxlytoceras aff. audax 213 P L A T E 3 Eolytoceras tasekoi, Sulciferites cf. trapezoidalis, Angulaticeras spezianum, Sulciferites ? sp., Badouxia cf. occidentals, Sulciferites marmoreus, Angulaticeras cf. ventneosum 215 P L A T E 4 Badouxia oregonensis, Badouxia columbiae, Badouxia aff. occidentahs, Badouxia ? sp 217 P L A T E 5 Badouxia canadensis, Badouxia columbiae, Sunrisites senililevis, Vermiceras sp 219 P L A T E 6 l^erTTwceras ex gr. coregonense, Vermiceras cf. supraspiratum, Metophioceras aff. rotanum, Vermiceras sp., Coroniceras ? sp 221 P L A T E 7 Metophioceras cf. rursicostatum, Arnioceras miserabile, Arnioceras cf. densicosta, Metophioceras spp., Armoceras sp., Arie t i t inae gen. et sp. indet 223 P L A T E 8 Arnioceras cf. oppeli, Arnioceras ex gr. mendax, Arnioceras arnouldi 225 P L A T E 9 Arnioceras arnouldi, Arnioceras cf. speciosum, Hyp aster ocer as ? sp 227 P L A T E 10 Arnioceras ex gr. ceratitoides, Epophioceras aff. cannatum, Asteroceras cf. vanans, Asteroceras aff. margarita, Asteroceras saltriense ? 229 P L A T E 11 Plesechioceras ? harbledownense, Plesechioceras ? h arble down ens e ? 231 P L A T E 12 Plesechioceras yakounense, Paltechioc eras aff. boehmi, Plesechioceras? cf. aklavikense.... 233 P L A T E 13 Paltechioceras cf. romanicum, Gleviceras cf. subguibalianum, Radstockiceras ex gr. numismale, Paltechioceras cf. rothpletzi, Paltechioceras sp 235 P L A T E 14 Crucilobiceras ? sp., Oxynoticeras cf. simpsoni, Posidonotis semiplicata, Tetraspidoceras pacificum, Oxynoticerat idae gen. et sp. indet., Tetraspidoceras sp., Tetraspidoceras recognitum 237 P L A T E 15 Tetraspidoceras recognitum, Posidonotis semiplicata, Crucilobiceras ? sp 239 P L A T E 16 Phricodoceras sp., F i s h remains, Miltoceras sp., Gemmellaroceras sp., Alsatites cf. proaries 242 xi P L A T E 17 Camptonectes (Camptochlamys) sp., Otapvna sp. A , Pteriacea gen. et sp. indet. 1, Pteriacea gen. et sp. indet. 2, Pseudomytiloides sp., Limea ? sp., Oxytoma sp., Ichthyosaur vertebral centrum, Isocrinida gen. et sp. indet 243 xii A C K N O W L E D G E M E N T This thesis was produced under the guidance and supervision of P . L . Smi th . I wish to express my thanks for his continuous support, which often extended beyond the l imits of this project, his advice on research problems, and his patience as I adapted to a very different environment. Mos t of the funding for this study was provided through an N S E R C grant to Smi th . H . W . Tipper (Geological Survey of Canada) int roduced me to the rewarding and demanding field work in the Queen Charlot te Islands and shared his wealth of knowledge on Jurassic biostratigraphy. He provided working space and access to his lab facilities in the G S C . He is also thanked for arranging the loan of type material from the G S C collections and for making his research material from the Taseko Lakes area available for comparative studies. I am grateful for the use of Smith 's and Tipper ' s research l ibrary which proved to be an invaluable resource. Their detailed and thoughtfu comments on earlier drafts of this thesis resulted in major improvements of the text. W . C . Barnes ( U B C ) and G . E . Rouse ( U B C ) acted as members of my supervisory committee and I benefited from their guidance and valuable comments on the thesis manuscript . The research was part ly funded by the Front ier Geoscience P rogram of the G S C and I wish to express my thanks to this organization for the logistical support in the summers of 1989 and 1990. Thanks are especially due to J . W . Haggart ( G S C ) for making my whole family feel at home in the Queen Charlot te Islands. M . Neylan provided assistance in the field. Enl ightening discussions wi th D . G . Taylor (Por t land) and the oppor tuni ty of s tudying his part ly unpublished material from Nevada and Oregon contr ibuted to my understanding of some systematic and stratigraphic problems. G . Bloos (Stuttgart) and S. E . Damborenea ( L a Plata) helped interpret taxonomic problems related to the arietitids and bivalves, respectively. Fel low graduate students part icipated in the formation of this s tudy in many ways. G . Jakobs helped throughout this project, in the field as well as in the lab and by numerous discussions. The company of C . G a m b a , J . Indrelid, J . Hesthammer, P . Lewis, and S. Ta i t e was most enjoyable in the field, while discussions about the geology of the Queen Charlottes enhanced my th ink ing on various topics. Tai te is also thanked for the time and energy she spent in introducing me to the geology of the Tasu Sound area, and for making her collections from Section R available. B . Liang gave advice on comput ing problems. I wish to express my thanks to K . Gordanier -Smi th for the caring and professional photography related to this project. Dur ing my stay in Canada I enjoyed the support and encouragement of my collegues in the Departments of Paleontology of the Hungar ian Na tu ra l His tory M u s e u m and the Eotvos Lorand Univers i ty , Budapest . M y studies at U B C were an endeavor for the whole family. Our parents gave a reassuring link to home while tolerating our long absence. I owe much to my wife M a r i a , who shared only l i t t le of the pleasures but most of the hardship related to my work. W i t h o u t her whole-hearted support the tightrope performance of researching, s tudying and parenting simultaneously would not have been possible. I N T R O D U C T I O N 1 C H A P T E R 1 I N T R O D U C T I O N 1.1 L O C A T I O N A N D A C C E S S OF T H E S T U D Y A R E A The Queen Char lot te Islands lie on the western edge of the continental margin off central B r i t i sh Co lumbia . The conspicuously wedge-shaped archipelago consists of more than 150 islands of which the two major ones are Graham Island in the north and Moresby Island in the south. A helicopter was used to provide transportation to Kennecott Point in northwest G r a h a m Island. Sections in central G r a h a m Island are easily accessible from Queen Charlot te C i t y on a network of logging roads. Shoreline sections of M a u d e Island and Sandilands Island were reached by inflatable boat. Localit ies in the T a s u Sound area are accessible by four-wheel drive vehicle on logging roads from Sewell Inlet logging camp. A helicopter or boat can be used to get to K u n g a Island, where an inflatable boat is helpful to move from one section to the other." For easy reference stratigraphic sections are coded wi th capital letters from nor th to south. Fossiliferous levels (collection sites) wi th in each section are numbered in ascending stratigraphic order. Local i ty information is listed in the Append ix . The location of the measured sections where fossil collections were obtained is shown on F i g . 1-1. Th i s s tudy is a contr ibut ion to the Front ier Geoscience Program in the Queen Char lo t te Islands. The mandate of the Front ier Geoscience P rogram is to comprehensively investigate the onshore geology to help future offshore hydrocarbon exploration. The Upper Nor ian to Lower Pl iensbachian Sandilands and Ghost Creek Format ions are proven potential source rocks; therefore biostratigraphic studies are of v i ta l importance. The r ich latest Hettangian to earliest Pliensbachian ammonite fauna of the upper part of the Sandilands and lower part of the Ghost Creek Formations, well suited for precise dating, was known 1.2 P U R P O S E OF S T U D Y INTRODUCTION 0 5 10 20 30 40 50 Figure 1-1 Index map of the measured stratigraphic sections and fossil localities. INTRODUCTION 3 al though no detailed study has been undertaken earlier. Also , this s tudy was ini t ia ted as part of an effort to erect a regional ammonite zonation for the Lower Jurassic of western N o r t h Amer i ca . The Queen Charlot te Islands yield one of the most diverse and abundant assemblage of this age. The main aims of this thesis can be summarized as follows: 1. T o provide a complete taxonomic treatment of the latest Het tangian to earliest Pl iensbachian ammonite fauna collected from the Queen Charlot te Islands. 2. To delimit in measured sections the stratigraphic ranges of the taxa described. 3. T o establish a local ammonite zonation val id for the Queen Charlot te Islands wi th possible extension of its use to other areas in western N o r t h Amer ica . 4. T o use the above zonal scheme for correlation wi th other areas in western Nor th A m e r i c a and to discuss the possibilities of global correlation. 5. T o analyze the paleobiogeographic affinities of the Queen Char lot te fauna to contribute data about the history of Wrangel l ia . 6. T o use the paleoecological conclusions derived from ammonite, trace fossil, bivalve, and other macrofossil assemblages to help interpret the depositional environment of the upper part of the Sandilands Format ion . 7. T o apply high resolution biochronology to the problems of basin evolution such as the lateral thickness trends wi th in the studied part of the Sandilands Format ion and the t iming of t ransi t ion of the Sandilands and Ghost Creek Formations, and to review some aspects of the sedimentology and depositional history of the Sandilands Format ion . 1.3 PREVIOUS WORK Geological investigation of the Queen Charlot te Islands dates back to the 1870's and paleontological studies have formed a crucial part since the beginning. Comprehensive summaries of Jurassic stratigraphy INTRODUCTION 4 were given by McLBARN (1949) and more recently by CAMERON and TIPPER (1985). Instead of largely repeating these, a brief account is given wi th special reference to the Sandilands Format ion . In 1872 J . Richardson was the first geologist to visit the Queen Charlot te Islands but his report (RICHARDSON, 1873) was pr imar i ly concerned wi th the "coal-bearing strata" and did not deal wi th what is Lower Jurassic according to our modern understanding. BILLINGS (1873) examined Richardson's fossil collections and, based on ammonites, concluded that Jurassic as well as Cretaceous rocks were present. G . M. Dawson's fundamental work is the first comprehensive treatment of the geology of the islands. His opus (DAWSON, 1880) is jus t ly amongst the classic pioneer works on Canadian geology. He recognized the succession of four unnamed units: a thick pile of volcanic rocks overlain by grey limestones, flaggy, black, Monotis-beanng beds and flaggy, black argillites. He visited several localities where the black argillite (1. e. the Sandilands Format ion in modern terms) cropped out, inc luding Carpenter B a y and Section Cove in southern Moresby Island (SUTHERLAND BROWN 1968, p. 51, 55), K u n g a Island (p. 61), Skedans Bay (p. 62) and M a u d e Island (p. 63). He considered the whole section as Triassic based mainly on the age of Monotis subcirculans. A major disturbance was envisaged separating the deposition of this sequence and the overlying package of five units ( E to A ) , the age of which was thought to be Cretaceous. U n i t E (the "Lower Sandstones") is probably equivalent to the Maude Group of modern l i thostratigraphy. A persistent confusion of Jurassic and Cretaceous fossils stemmed from a failure to recognize two sandstone units of closely similar lithology but of dis t inct ly different age. J . F . Whiteaves carried out much of the early paleontological research on Mesozoic faunas. He recognized Jurassic as well as Cretaceous faunas but favoured a Cretaceous age having been puzzled by the above mentioned problem and confused by improper ly located collections (WHITEAVES, 1883, 1884). The revision of Dawson's stratigraphic framework started wi th the recognition of a major unconformity between Uni ts E..and D (i.e. present-day Maude and Y a k o u n groups) (CLAPP, 1914). The lithologic description of argillites, locally called "r ibbon rocks" wi th in unit E probably refers to what is now known as the Sandilands Format ion (CLAPP, 1914, p. 19). MACKENZIE (1916) named the Maude Format ion and included the black argillite. INTRODUCTION 5 The next important contribution was made by F. H. McLearn in several papers devoted to the Jurassic-Cretaceous rocks and fossils of the islands. In a detailed treatment of the Maude Formation (MCLEARN, 1949) he referred to the argillites as unfossiliferous beds found on the south shore of Maude Island, in Whiteaves Bay, and on Sandilands Island. The oldest assemblage described by him was the Late Pliensbachian Fannmoceras fauna. A . Sutherland Brown's thorough and comprehensive mapping was a major step beyond the earlier reconnaissance work. His stratigraphic revision led to the introduction of the Kunga Formation (SUTHERLAND BROWN and JEFFREY, I960) and its further subdivision into three informal members, the highest being the "black argillite" member (SUTHERLAND BROWN, 1968). Fossils from this unit identified by H. FREBOLD (SUTHERLAND BROWN, 1968, p. 60-61: Armotites {Melanhippites) harbledownense, Arniotites sp., and Arietites s.l.) indicated a Sinemurian age. In fact, this was the first published record of Sinemurian fossils from the Queen Charlotte Islands. The Maude Formation was retained in a restricted sense as compared to MC LEARN's (1949) interpretation. Another major advance in refining the lithostratigraphy was made by CAMERON and TIPPER (1985). The Kunga and Maude formations were elevated to group status and SUTHERLAND BROWN's (1968) members within his Kunga Formation were treated as independent formations: the "black argillite" was formally named the Sandilands Formation. Similarly the Maude Group was subdivided into five formations, the lowermost being the Ghost Creek Formation (discussed to some extent later in the present study). Likewise a major step forward was made by working out a biostratigraphic scheme (for details see Chapter 2) INTRODUCTION 6 Interest in the geology of the Queen Char lot te Islands has been spurred by the Front ier Geoscience Program of the Geological Survey of Canada aimed at producing comprehensive, high quality, 1:50 000 scale maps of the islands and a synthesis of their geological evolution. Detai led studies at Kennecott Poin t for the first t ime furnished faunal evidence for the presence of uppermost Triassic (CARTER et al., 1989) and Hettangian (TIPPER, 1989) strata wi th in the Sandilands Forma t ion . For the Sinemurian, prel iminary results of the present study were published by PALFY et al. (1990). 1.4 METHODS A n extensive fossil collection obtained dur ing a full field season in 1989 and an addit ional 3 weeks field work in 1990 formed the basis of the present study. Examina t ion of the preexisting collections of the Geological Survey of Canada added supplementary information. Collections were made from measured stratigraphic sections. The majority of these were measured using the more accurate B r u n t o n compass and tape technique except for K u n g a Island where the Jacob's staff (Pogo stick) method was employed (COMPTON, 1962). In the first case the true stratigraphic thicknesses were calculated ut i l iz ing the For t ran program S T R A T (SMITH, 1976). The considerable thickness of the formation (at some sections several hundred meters exposed), the relative scarcity of fossils at some horizons, and the laminated lithology renders the ideal case of bed-by-bed collection imprac t ica l . However, part icular care was taken to ensure that collections were as closely spaced as possible. The mean stratigraphic distance between superjacent collections is 2-3 m wi th a spread between 0.2 and 30 m. In the taxonomic work, the majority of the N o r t h Amer i can Sinemurian ammonoid type material (that of FREBOLD and CRICKMAY) was studied for comparison. T o facilitate data entry, qualitative and quantitative descriptions conform wi th the A M M O N database developed at U B C (SMITH, 1986). G E N E R A L G E O L O G Y C H A P T E R 2 G E N E R A L G E O L O G Y 2.1 G E O L O G I C A L S E T T I N G OF T H E Q U E E N C H A R L O T T E I S L A N D S The Queen Charlot te Islands are located on the western margin of the Canadian Cord i l l e ra forming part of the Insular Bel t . The western part of the Cord i l l e ra is viewed as a collage of allochthonous terranes, foreign to the N o r t h Amer ican craton. Each terrane is a fault-bounded crustal fragment w i t h dist inctive stratigraphy (CONEY et al. , 1980, MONGER, 1984). The Queen Char lot te Islands share their Upper Paleozoic to Lower Jurassic stratigraphic record wi th south-central Alaska , most of Vancouver Island, and disputedly wi th northeastern Oregon, and are considered part of the displaced terrane Wrangel l ia (JONES et al. , 1977) (F ig . 2-1). Compel l ing paleomagnetic and paleontologic evidence suggests that Wrange l l i a was formed far south of its present latitude (HlLLHOUSE, 1977; YOLE and IRVING, 1980; TAYLOR et al. , 1984). Geophysical data for its original longitude and possible trajectories prior to docking to Nor th A m e r i c a are not well constrained (DEBICHE et al. , 1987). Different plate tectonic models have been proposed to explain the accretion of Wrange l l i a to Nor th Amer ica . The amalgamation of Wrange l l i a and the Alexander terrane may have led to the formation of a composite terrane by the Late Jurassic (MONGER et al., 1982) as evidenced by the overlapping Grav ina -Nutzo t in assemblage in A l a s k a (BERG et al. , 1972). A n alternative interpretat ion suggests that these two terranes were assembled as early as the Late Paleozoic (GARDNER et al . , 1988). The accretion of this composite terrane lead to the onset of magmatic act ivi ty in the Coast P lu ton ic Complex (MONGER et al. , 1982) in mid-Ear ly Cretaceous time (ARMSTRONG, 1988). Al te rna t ive ly , the Coast P lu ton ic Complex may represent the root of a magmatic arc wi th in the earlier assembled Insular and Intramontane composite terranes formed by an east-dipping subduct ion zone (VAN DER HEYDEN, 1989). T h e subsequent fragmentation and nor thward translation by right-lateral strike-slip movements is possibly a result of the oblique convergence of Faral lon, K u l a , and Nor th Amer ican plates (DEBICHE et al. , 1987). GENERAL GEOLOGY Figure 2-1 Tectonostratigraphic terranes of the Canadian Cordillera (after ARMSTRONG, 1988). G E N E R A L G E O L O G Y 2.2 S T R A T I G R A P H Y 2.2.1 SYNOPSIS OF UPPER TRIASSIC TO LOWER JURASSIC STRATIGRAPHY Upper Triassic to Lower Jurassic strata of the Queen Charlotte Islands form a coherent sedimentary cycle in a continuous sequence (Fig. 2-2). A brief account is given here to provide the necessary background for the interpretation of Sinemurian rocks. The Karmutsen Formation is a several kilometer thick pile of mostly submarine tholeiitic basalts CHRONOSTRATIGRAPHY Ma LITHOSTRATIGRAPHY 1111111111111111ITTTTT o co co < or ZD O 10 oo < rr >-_ J or < LU AALENIAN TOARCIAN PLIENSBACHIAN SINEMURIAN Z04 HETTANGIAN NORIAN CAR N IAN LADINIAN 187 193 198 208 225 230 PHANTOM CREEK FORMATION WHITEAVES FORMATION FANNIN FORMATION GHOST CREEK FORMATION SANDILANDS FORMATION PERIL FORMATION SADLER LIMESTONE KARMUTSEN FORMATION o_ 3 O CH O LU a < zs. a. ZD o CH < o zz ZD Figure 2-2 Upper Triassic-Lower Jurassic lithostratigraphy of the Queen Charlotte Islands (modified from LEWIS et al, in press). G E N E R A L G E O L O G Y 10 forming the basement of the overlying K u n g a and Maude Group sedimentary rocks. Geochemical characteristics suggest a rift ing back-arc environment for the Karmutsen basalts (ANDREW and GODWIN, 1989, PLAFKER et al., 1989). The K a r n i a n Sadler Limestone represents low-energy subt idal environment of a carbonate shelf (DESROCHERS and ORCHARD, in press). Deepening of the shelf is recorded by dark calcareous mudstones of the P e r i l Format ion ranging up to Late Nor ian time. The Upper N o n a n to Lower Pl iensbachian Sandilands and overlying Ghost Creek Formations, deposited in a more distal basin, are discussed in detail below. The F a n n i n Format ion (Lower Pliensbachian to lowermost Toarcian) is considered a regressive succession (CAMERON and TIPPER, 1985). The paraconformably overlying Whiteaves and P h a n t o m Creek Formations probably represent a subsequent, smaller, eustatically controlled sedimentary cycle (CAMERON and TIPPER, 1985). 2.2.2 SANDILANDS FORMATION The Sandilands Format ion was introduced by CAMERON and TIPPER (1985) for the black argillite member of SUTHERLAND BROWN (1968) after raising the formerly used K u n g a Format ion to group status. The Sandilands Format ion ranges in age from the Late Nor ian (CARTER et al . , 1989) to the Ea r ly Pl iensbachian (SMITH et a l , 1990). Detailed l i thological description of the Sandilands Format ion is given by SUTHERLAND BROWN (1968) and CAMERON and TIPPER (1985). It is typical ly composed of mterbedded dark shale and dark grey or blue siltstone. F ine to m e d i u m grained, sometimes graded sandstone and tuffaceous interbeds are common. The rock is generally th in ly bedded, ind iv idua l beds seldom exceed 10 c m in thickness, averaging between 2-5 cm. It is well indura ted and fissile along the bedding planes. Tu rb id i t i c origin for part of the formation was proposed by CAMERON and TIPPER (1985). Our field observations suggest that the entire formation can be interpreted by a distal turbidi te depositional model. Complete B o u m a sequences are not found. Graded sandstones (division A) are common at Kennecot t Poin t but do not exceed 5 c m in thickness. Massive or parallel laminated sandstone (division B ) form several G E N E R A L G E O L O G Y 11 unusually thick beds (up to 1 m) on K u n g a Island (Section T ) and in the Tasu Sound area (Section R ) . R ipp led and convolute bedding are most frequent at Kennecott Po in t . Volumet r ica l ly the formation is mainly composed of division D-E couplets of the B o u m a sequence. Together wi th the remarkable uniformity and lack of lateral changes of ind iv idua l beds in outcrop, this suggests basin pla in (MUTTI, 1977) and unchannelized lower fan facies (WALKER, 1984). The overall dark color of the formation is related to its high organic content due to prevail ing anoxic bottom conditions. Support ing paleoecological evidence is presented in Chapter 5. The anaerobic-dysaerobic regime may have been controlled by basin topography (silled basin model: DEMAISON and MOORE, 1980) and/or high pr imary product ivi ty . The hydrocarbon source rock potent ia l of the formation is assessed by BUSTIN and MACAULEY (1988) and VELLUTINI (1988). The total thickness of the formation is difficult to estimate due to s t ructural complexities. A n estimate of the uppermost Hettangian to lowermost Pliensbachian part is made in Chapter 3. The subtle increase in thickness to the south is also discussed in Chapter 3. The lateral facies changes over a distance of approximately 120 k m in N W - S E direction are minor. Th i s uniformity is possibly greater if the closely similar Harbledown Format ion exposed near the northeastern t ip of Vancouver Island is considered (JELETZKY, 1970). CAMERON and TIPPER (1985) proposed a back-arc basin depositional model wi th volcanic arc source ly ing to the west. Latera l cont inui ty along the basin axis is in keeping wi th this interpretation and one would expect more proximal facies to the west. In fact the westernmost localities (Kennecott Poin t and Section R at Tasu Sound) differ from the others in having more A , B, and C divisions of the B o u m a sequence. Section R also yielded ornate gastropods and coral fragments interpreted as a resedimented shallow water assemblage from a i m thick quartz-rich sandstone bed (S. TAITE, pers. comm.). A t Kennecott Poin t , west of the measured sections massive sandstone beds possibly represent channel facies (C . GAMBA, pers. comm.) . T h i c k sandstone beds wi th in the Sandilands Format ion are also found near Shields Bay (P . LEWIS, pers. comm.) . The more proximal facies of a fan system may be submerged or cut off by the Queen Charlot te Fau l t system and transported farther to northwest. W i t h regard to a source area, the Talkeetna A r c of the Peninsular terrane in southeast A l a s k a G E N E R A L G E O L O G Y 12 and the Bonanza Group volcanic rocks of Vancouver Island were suggested as possibilities (CAMERON and TIPPER, 1985, LEWIS et al. , in press). The observed southward thickening and the shift of Sandi lands /Ghos t Creek transi t ion together wi th the westward increasing proximal i ty point to a source in southwest according to present coordinates. S.S.3 GHOST CREEK FORMATION The Ghost Creek Format ion was introduced by CAMERON and TIPPER (1985) for a recessive dark shale unit comformably overlying the Sandilands Format ion . The contact is gradational and in the studied sections no sharp boundary can be drawn between the two formations. Th i s s tudy is concerned only wi th the lower part of the Ghost Creek Format ion in central G r a h a m Island and Maude Island. The age and the diachronous nature of the contact is discussed in Chapter 3. The Ghost Creek Format ion ranges from the Recogni tum Zone (introduced here as probably latest Sinemurian to earliest Pl iensbachian) to the Whiteavesi Zone (Ear ly Pliensbachian) in age (TIPPER et al. , 1991). The predominant li thology is soft, dark shale. Sandstone and tuffaceous interbeds are less frequent than in the under lying Sandilands Format ion . Th i s indicates decreased volcanic act ivi ty in the source area or alternatively increased distance from the depositional site, resulting in the preponderance of hemipelagic mud sedimentation less frequently interrupted by turbidites or tuffaceous interbeds. B I O S T R A T I G R A P H Y A N D B I O C H R O N O L O G Y 13 C H A P T E R 3 B I O S T R A T I G R A P H Y A N D B I O C H R O N O L O G Y 3.1 I N T R O D U C T I O N Ammoni tes , the most abundant macrofossils of the Sandilands Format ion , are the preferred fossils for dating and correlation of marine Mesozoic rocks. In Europe, where stratigraphic studies and the use of ammonites for correlation date back to the late 1700's, OPPBL and QUENSTEDT laid down the foundation of a Jurassic zonal scheme nearly 150 years ago. A relentless effort to refine this framework culminated in a classic paper by DEAN et al . (1961) formalizing a standard zonation for the Lower Jurassic of northwest Europe. Trad i t ion and superior level of knowledge justify its status as being the pr imary standard for biochronology (CALLOMON, 1984). However, the effect of ammonite provincial ism was recognized early (NEUMAYR, 1883); e.g. WAHNER in his classical series of monographs (1882-1898) proposed a zonal scheme for the Alp ine region different from that of northwest Europe due to the significant faunal differences. The correlation between the Mediterranean and Northwest European provinces has not yet been fully resolved and this emphasizes the need for independent regional zonal schemes (CALLOMON, 1984). Reconnaissance work in Western Canada relied on gross correlation wi th the northwest European standard (e.g. FREBOLD and TIPPER, 1970). More detailed analysis has, however, demonstrated that paleobiogeographic differences, inc luding endemic Pacific elements, overall closer affinities wi th Te thyan sequences, and different ranges of common taxa, warrant the erection of a regional chronostratigraphic standard useful for regional correlation before proceeding to a global scale. In this context a Pl iensbachian zonation for Nor th A m e r i c a was recently developed by SMITH et al . (1988). In this s tudy a local biostratigraphic zonation for the uppermost Hettangian to lowermost Pliensbachian of the Queen Char lot te Islands is proposed. The ranges of ammonite taxa are documented in measured sections. S ix ammonite zones are established and their usefulness for correlation wi th in the Queen Charlotte Islands and subdivision of the li thologically monotonous Sandilands Format ion is demonstrated. B I O S T R A T I G R A P H Y A N D B I O C H R O N O L O G Y 14 Geological implications such as thickness trends and age relationship wi th the overlying Ghost Creek Format ion are also discussed. The fossiliferous and apparently complete uppermost Hettangian to lowermost Pl iensbachian succession in the Queen Char lot te Islands provides a basis to the erection of an ammonite chronostratigraphic zonation for the Sinemurian of western Nor th Amer ica . V a l i d chronozones should be based on biozones recognizable over a wide geographic area (CALLOMON, 1984; GUEX, 1987). The local zones are evaluated in this wider perspective by comparison wi th the record of other Nor th Amer ican localities and possible correlation wi th the pr imary standard northwest European scale as well as zonations developed in other areas of the world . The ongoing project of Lower Jurassic biostratigraphy of the Queen Charlot te Islands involves a team of biostratigraphers. A n ammonite zonation such as the one proposed here, can serve as a reference against which zonal schemes of other fossil groups (e.g. radiolanans, nannofossils, ichthyoli ths) can be calibrated (TIPPER et a l , 1991). 3.2 T H E A M M O N I T E Z O N A T I O N F O R T H E Q U E E N C H A R L O T T E I S L A N D S F r o m the data presented in chapter 3.3 a composite range chart was compiled ( F i g 3-1). Based on the vert ical d is t r ibut ion of ammonoid taxa a local zonal scheme is proposed for the uppermost Het tangian to lowermost Pl iensbachian of the Queen Charlot te Islands. The characteristics of the six ammonite assemblage zones in ascending order are as follows. 3.2.1 The Canadensis Zone The Canadensis Zone, proposed by FREBOLD (1967), was the first formal ammonite zone in the Lower Jurassic of N o r t h Amer i ca . In the Queen Charlot te Islands it is characterized by a rich assemblage of the very abundant Badouxia, early arietitids and endemic lytoceratids accompanied by rare schlotheimiids BIOSTRATIGRAPHY AND BIOCHRONOLOGY 15 STAGE HETT. SINEMURIAN ? PLI. \ ZONE T A X A ^ X Canadensis "Coroniceras" Arnouldi Varians Harbledownense Recognitum Imlayi Schtothemia n. sp. Afsatitesct proah»s Badouxia oregonensis Backxixia canadensis Vermiceras cf. supraspiraturn • Badouxia cf. occidentals Eolytoceras ? guexi? Verrriceras ex gr. coregonense Eotytoceras tasekoi Anguiaticeras cf. ventrteosum ScJcrferrtes cf. trapezotdals Metophioceras cf. rurstcostadum Sunrisftes senilevts Arietffinae gen. et sp. rtdet Lytoceras spp. • Ectocerrtrites ? sp. Metophioceras spp. Badouxia columbiae Metophioceras aff. rotarium Badouxia ?sp. • Badouxia aft. c«rfdeinta<s Lytoceras sp. Sutelferites rnarmoreus Sutaferites ? sp. Vermiceras sp. • • • • Phytoceras sp. Juraphyftes sp. Juraphyites cf. tarwytvanieus Arnioceras sp. Coroniceras ? spp. • • Arnioceras arnoukf Arnioceras ex gr. mendax Arnioceras cf. speciosum Arnioceras ex gr. ceratitoides Arnioceras mtserabet Audaxtytoceras afl. audax Juraphyftes cf. hiatus Adnethiceras ct. adnethicum Arnioceras cf. densicosta Anguiaticeras spezianum • • • • Arnioceras ct. oppei Tragotytoceras 7 sp. Asteroceras afl. margarita Epophtocerao aff. cahnatum Asteroceras cf. varians • Asteroceras sattrieme ? Hypasteroceras ? sp. Oxynoticeras cf. simpsoni Plesechioceras yakounense Plesechioceras ? cf. aktavtkense • — Tetraspidoceras sp. Gleviceras cf. subguibalanurn Tetraspidoceras pacificum Plesechioceras ? rtarbiedownense Pattechioceras cf. romaricurn • • • Paltechioceras aff. boehmi Pattechioceras cf. rothpietzi Pattechioceras sp. Posidonots serrspfcata C^uclobiceras ? sp. • • Juraphyftes aff. narcf RaoStocWceras ex gr. riumismaie Tetraspidoceras recognitum OxynoticeratkJae gen. et sp. indet Qerrrnelaroceras sp. • • — Mltoceras sp. PseudoskJroeeras imlayi Figure 3-1 Zonation and relative stratigraphic ranges of latest Hettangian to earliest Pliensbachian ammonites of the Queen Charlotte Islands. BIOSTRATIGRAPHY AND BIOCHRONOLOGY 16 and phylloceratids. The base of the zone is defined by the first appearance of Badouxia canadensis wh ich is common throughout the zone except, perhaps, the topmost part. It is most abundant in the lower half of the unit . Badouxia oregonensis and possibly Vermiceras cf. supraspiratum range upward from the subjacent Upper Hettangian unit to the basal part of this zone. The endemic Eolytoceras tasekoi and E. ? guexi ? are confined to the zone. Sporadic occurrences of schlotheimiids (Angulaticeras cf. ventricosum, Sulciferites marmoreus, Sulciferites cf. trapezoidalis, Sulciferites ? sp.) are recorded throughout the zone. Vermiceras ex gr. coregonense is found typical ly in the lower part. A twofold subdivision wi th in the zone already suggested by FREBOLD (1967) and more recently by TAYLOR (1991) is possible, as Badouxia columbiae along wi th more diversified Metophioceras spp. are restricted to the upper part. Vermiceras sp. (possibly a new species) occurs only at the top of the zone. The best reference sections of the zone at Kennecott Poin t are Section D and F whereas Section G and B help to define its lower and upper boundaries. The zone is also recognized in Section O (Skidegate Inlet) and S ( K u n g a Island). 3.2.2 The "Coroniceras" Zone The "Coroniceras" Zone is introduced to embrace an interval between the Canadensis and A r n o u l d i Zones represented by a generally poorly preserved and poorly understood assemblage of Coroniceras ? spp., the persistent Juraphyllites cf. transylvanicus together wi th Metophioceras aff. rotarium, M. spp., and Angulaticeras cf. ventricosum, al l ranging up from wi th in the Canadensis Zone. Arnioceras sp. first appears at the base of the zone. No complete section of this unit is known in the islands. Its base is defined in Section B at Kennecott Po in t . The lowest beds of Section T and parts of Section S at K u n g a Island are also assigned to this zone. BIOSTRATIGRAPHY AND BIOCHRONOLOGY 17 3.2.3 The Arnouldi Zone The A r n o u l d i Zone is characterized by a rather diverse assemblage of Arnioceras species, of which A. arnouldi appears first. It persists into the Var ians Zone together wi th A. cf. oppeli and A. ex gr. ceratitoides. Arnioceras miserabile, A. cf. densicosta, A. cf. speciosum, and A. ex gr. mend ax seem to be confined to this zone. Juraphyllites cf. transylvaniens last appears wi th in this unit . Several extremely rare lytoceratids (Audaxlyioceras aff. audax, Adnethiceras cf. adnethicum, Tragolytoceras sp.) are also recorded from the zone. The upper part of the zone is documented in section H . The zone is proved in Sections M and N in Skidegate Inlet and widespread in the T a s u Sound area (Sections P , Q , R ) . It is well developed but tectonically disrupted in both Section S and T on K u n g a Island. 3.2.4 The Varians Zone This zone is defined by an assemblage of asteroceratids confined to this unit and cooccurring, in its lower part, wi th long-ranging species of Arnioceras (A. arnouldi, A. cf. speciosum, A. cf. oppeli, A. ex gr. ceratitoides). The first Asteroceras to appear is A. aff. margarita, accompanied at higher levels by A. cf. varians and A. saltriense ?. Other significant elements confined to this unit are Epophioceras aff. cannaium and Hyp asteroceras ? sp. A t Y a k o u n River the upper part of the zone is exposed in Section I whereas section H contains only a faulted slice of its lower part. The zone is present in Maude Island (Section M ) and well represented in a tectonically complex section in K u n g a Island (Section S and T ) . BIOSTRATIGRAPHY AND BIOCHRONOLOGY 18 3.2.5 The Harbledownense Zone The base of this zone, as understood here, is marked by the first appearance of oxynoticeratids and echioceratids. The first family is represented by Oxynoticeras cf. sirrvpsom and Gleviceras cf. subguibalianum, restricted to the lower part of the zone. Th i s interval is dominated by the closely related species of Plesechioceras (P. yakounense, P. ? harbledownense, P. ? cf. aklavikense) of which only P. ? harbledownense ranges to the upper part of the unit . Fur ther investigation may warrant subzonal subdivision based on various species of Paltechioceras (P. aff. boehmi, P. cf. romamcum, P. cf. . rothpletzi, P. sp.) cooccurring in the upper part of the zone. The occurrence of Tetraspidoceras pacificum and Tetraspidoceras ? sp. near the base of the zone is notable. Section H at Y a k o u n River provides a reference section for the zone which is also present in Sections I, K , M , S, and T . 3.2.6 The Recognitum Zone Characterist ic species include eoderoceratids, Juraphyllites aff. nardii and the pect inid Posidonotis semiplicata. Th i s bivalve commonly occurs crowded on bedding planes, and ranges throughout most of the zone together wi th Crucilobiceras ? sp. Juraphyllites aff. nardii is abundant in some beds in the upper part of zone and ranges to the Imlayi Zone. Tetraspidoceras recognitum seems to be confined to the topmost part of the unit where it can be accompanied by rare oxynoticeratids (Radstockiceras ex gr. numismale and Oxinoticerat idae gen. et sp. indet.). No continuously fossiliferous transit ion between the Harbledownense and Recogn i tum Zones has been seen; in all cases there is a significant barren interval between the last Paltechioceras and the first Posidonotis or Crucilobiceras. Section H at Y a k o u n River is designated as a reference section. The upper part of the zone is known from Maude Island (Section M ) and the transi t ion to the Imlayi Zone is also documented in Section T ( K u n g a Island). B I O S T R A T I G R A P H Y A N D B I O C H R O N O L O G Y 19 3.3 B I O S T R A T I G R A P H Y OF T H E M E A S U R E D S E C T I O N S 3.3.1 NORTHWEST GRAHAM ISLAND K E N N E C O T T P O I N T ( S E C T I O N S A - G ) A t Kennecott Point the Upper Triassic, Hettangian, and Lower Sinemurian parts of the Sandilands Format ion are well exposed resting conformably on the Pe r i l Format ion , and capped by volcanics of the unconformably overlying Ter t ia ry Masset Format ion (HlCKSON, 1989). The Canadensis Zone crops out in a large in ter t idal platform where several smal l normal and sinistral transcurrent faults have resulted in repetitions. The location of the measured sections are shown on F i g . 3-2. A conspicous 40 cm thick carbonate cemented sandstone bed in the lower part of the Canadensis Zone is used as a lithologic marker to decipher s t ructural complications permi t t ing correlation between sections D , F , and G . The Canadensis Zone is the most fossiliferous unit ; it is nearly 35 m thick (F ig . 3-3 to 3-6). The lower contact of the Canadensis Zone is best exposed in Section G , al though the first appearance of Badouxia canadensis is not as far below the marker bed here as in Section D and F . The base of Section D is at the low tide line. Section F starts at a boulder field near a fault. The "Coroniceras" Zone contains a poor fauna. The highest beds in Section B yielded Arnioceras sp. along wi th Coroniceras ? spp. (F ig . 3-7). Section A at the southernmost tip of the Sandilands exposures is a tectonically repeated slice of the upper part of the Canadensis Zone. Y A K O U N R I V E R ( S E C T I O N S H A N D I) Section H on the west bank of Y a k o u n - R i v e r constitutes a long and relatively l i t t le disturbed sequence of the Sandilands and Ghos t Creek formations wi th A r n o u l d i Zone through Lower Pl iensbachian faunas (F ig . 3-8)'. The A r n o u l d i Zone and the Var ians Zone are in fault contact and much of the latter is 3.3.2 CENTRAL GRAHAM ISLAND Figure 3-2 Sketch map of Kennecott Point showing the location of the measured sections (Sections B-G). Section A is approximately 100 m south of Section B. BIOSTRATIGRAPHY AND BIOCHRONOLOGY • • • * • « « < • « « • • « • • • • • • • • I Shale Siltstone SdndsUone Interbedded sandstone, silt-stone and shale Graded sandstone V V ss V V V V V V Volcanic rocks (dyke or sill) a C J o a a Concretionary bed Covered interval A A A A A A Tuff, tuffaceous clay (not to scale) Limestone • • ^ • • • • i mm Fault (proved) Fault (assumed) Figure 3-3 Legend for the lithologic columns on F i g . 3-4 to F i g . 3-13. BIOSTRATIGRAPHY AND BIOCHRONOLOGY 22 C L U Z U u o x a. a. .5 -a c 3 c •" £ S - 3 n - ^ — ~" fl 3 5 »- ^ u •-• J fl o 3 "» 2 b .2 5 u on ,>• < U i w t. C ^ C K T »- — ^ SJ f*  o c q -S fl .r s — c c = A — w w ZONE I C 20 Q Z < D Z < 10 \- IS • IH — . 1 0 • I? •16 • tr • if li • U ;l • a •I •5 • <t Canadensis Figure 3-4 Biostratigraphy of Section D at Kennecott Point. BIOSTRATIGRAPHY AND BIOCHRONOLOGY 23 Z I-< c LH LU z u c d 4J .a w :2 " « o a: 2 s -= ? "2 — •a c 3. A * — u 5 H E ' P O O S C -c -o x U fl fl fl > a a £ c 3 ™ " J I £ ; ^ c "J 3 3 > (SI (/) U J U J 2 £ T" Illl •3 X .Z fl 3 yi w Ids 12 Q fl c u tun J) fl 11 oo c il 3 u « c u 3 l r "5. c 0 3 0 V rie -3 fl Xi S << CS 2 Z O N E 30 20 '13 id • I? 4- >6 20 A A A . - 15" Q Q Z < .(3 .10 •3 10 — 6 • 3 - L 1— 1 .1 Canadensis Figure 3-5 Biostratigraphy of Section F at Kennecott Point. BIOSTRATIGRAPHY AND BIOCHRONOLOGY FORMATION THICKNESS LITHOLOGY LEVEL Sunrisiles 1 sp. Vermiceras sp. indet. Schlotheimia n. sp. Alsatites cf. proaries Badouxia sp. indet. Badouxia canadensis Eolytoceras cf. tasekoi Z O N E SANDILANDS — 7 _ — ^ _ — _ 13 - 11 - tl - 10 - 3 - 6 - 7 - 6 - 5 - 1 - 3 -L - 1 Canadensis SANDILANDS 10 - * " — " — • ' SANDILANDS • • • Upper Hettangian SANDILANDS Figure 3-6 Biostratigraphy of Section G at Kennecott Point. BIOSTRATIGRAPHY AND BIOCHRONOLOGY 25 Z c C Q Z < _ i Q Z < cn « .5 cn cn LU Z U I 1-c o HZ I— c . x - c .£ u a . a = " o E 2 5 ij -2 £ « « •= 5 > 5 J < < 10 T 6 T 6 ...I' 3 ZONE "Coroniceras" Canadensis Figure 3-7 Biostratigraphy of Section B at Kennecott Point. BIOSTRATIGRAPHY AND BIOCHRONOLOGY 26 I P W Arn ioce ra s sp. indet. Arn ioce ra s miserabi le Arn ioce ra s ex gr. mendax Arn ioce ra s ex gr. cerat i toides Arn ioce ra s a rnou ld i Tragolytoceras i sp. Asteroceras cf. varians Asteroceras sp. indet. Epoph ioce ras aff. ca r ina tum Oxyno t i ce ras cf. s impsoni Oxyno t i ce ra t idae gen. et sp. indet P lesechioceras yakounense Glev ice ras cf. subgu iba l i anum Tetraspidoceras ? sp. P lesech ioceras ? ha rb ledownense P lesech ioceras ? aklavikense Pa l techioceras ? sp. indet-Pa l techioceras cf. r o m a n i c u m Pal tech ioceras aff. b o e h m i Pa l tech ioceras cf. r o l h p l e t z i Pa l techioceras sp. Pos idono t i s semipl icata C r u c i l o b i c e r a s ? sp. Juraphyll i tes aff. nardi i Tet raspidoceras r ecogn i tum Oxynoticeratidae gen. et sp. Indet Mil toce ra s ? sp. Gemmei l a roce ra s ? sp. < I cr it re 3 53 n O at -< N o Z m Figure 3-8 Biostratigraphy of Section H at Yakoun River, central Graham Island. BIOSTRATIGRAPHY AND BIOCHRONOLOGY 27 tectonically missing. The Harbledownense, Recogni tum, and Imlayi Zones are well documented wi th min ima l s t ructural complicat ion. The l i thostratigraphic transi t ion from the Sandilands to Ghost Creek Format ion occurs in the Recogni tum Zone. Section I contains exposures on both banks correctable across the Y a k o u n River further upstream from Section H , separated by a substantial covered interval at the elbow of river. Beds of the Var ians Zone are conformably overlain by the lower part of the Harbledownense Zone which is faulted against the Recogni tum Zone indicated by Posidonotis semiplicata (F ig . 3-9). " F L A G S T O N E " Q U A R R Y ( S E C T I O N K ) The Upper Sinemurian section of this quarry was the subject of a s tudy by McFARLANE (1988). The stratigraphic section together wi th a range chart is refigured in PALFY et al . (1990). N o new collections were obtained but the reevaluation of the material on hand confirmed that the section represents the Var ians and Harbledownense Zones. The succession is closely comparable wi th that of Section H . G H O S T M A I N R O A D C U T ( S E C T I O N L) A short section exposing the Recogni tum/Imlay i Zone transi t ion wi th in the Ghost Creek Format ion was freshly excavated in a roadcut yielding a small but significant fauna (F ig . 3-10). Fossiliferous levels of the two zones are separated by a less than 3 m interval yielding no ammonites. Posidonotis semiplicata was not found in place. The interval between Levels 10 and 11 is poorly exposed. 3.3.3 SKIDEGATE INLET AREA M A U D E I S L A N D ( S E C T I O N M ) The measured section consists of tectonically disrupted intervals separated by covered areas directly southwest of Section 8 of CAMERON and TIPPER (1985) on the south shore of M a u d e Island. Despite the lack of a continuous section the presence of A r n o u l d i , Var ians , Harbledownense, and Recogni tum Zones can be BIOSTRATIGRAPHY AND BIOCHRONOLOGY 28 Z O < O cn i n tu Z U C c r r— Q . I _2 % c :_c ic b> m C v. > , — .._ k. u </•. 13 i/> i» rS (9 C U u 4J O u O 5 0 (J a> U < < < < a . ZONE 20 en a z < _ i Q Z < cn 10 Harbledownense - 6 -3 -1 Varians Figure 3-9 Biostratigraphy of Section I at Yakoun River, central Graham Island. BIOSTRATIGRAPHY AND BIOCHRONOLOGY 29 Figure 3-10 Biostratigraphy of Section L at Ghost Main Roadcut, central Graham Island. BIOSTRATIGRAPHY AND BIOCHRONOLOGY 30 proved ( F i g 3-11). The longest unbroken sequence comprises overturned and steeply d ipping beds of the Recogn i tum Zone including the t ransi t ion of the Sandilands and Ghost Creek Format ions . It is exposed at the westernmost tip of the outcrop and truncated below but presumably very near to the base of the Imlayi Zone. S A N D I L A N D S I S L A N D ( S E C T I O N N) The type locality of the Sandilands Format ion (CAMERON and TIPPER, 1985) is tectonically complex and was not studied in detail . Arnioceras cf. arnouldi and A. ex gr. ceratitoides indicates the presence of the A r n o u l d i Zone. A L L I F O R D B A Y R O A D ( S E C T I O N O) A n old roadcut provides poor exposure of an approximately 12 m section of weathered Sandilands Format ion . The fauna includes Badouxia cf. canadensis and Eolytoceras sp. indicat ing the Canadensis Zone. 3.3.4 TASU SOUND AREA W 100 Q U A R R Y ( S E C T I O N P) Th i s quarry exposes approx. 20 m of the Sandilands Format ion wi th another 2 m excavated in a roadcut, presumably directly under lying the main section. Th i s lower level yielded a single specimen of Audaxlytoceras aff. audax along wi th Arnioceras spp. The faunal assemblage in the quarry includes Arnioceras cf. arnouldi, Arnioceras spp., and Juraphyllites cf. transylvaniens, and a single specimen of the rare schlotheimiid Angulaticeras spezianum. The assemblage suggests the A r n o u l d i Zone. W 160 Q U A R R Y ( S E C T I O N Q) Th i s quarry exposes 10 m of the Sandilands Format ion capped by a s i l l . The only indentifiable ammonites from the section are Arnioceras ex gr. ceratitoides and A. spp. .Deeply weathered float from the BIOSTRATIGRAPHY AND BIOCHRONOLOGY 31 Z < CZ 0 u_ U u • Z < i G Z < cn cn cn U X 1— "30" 29 ~ 8 . - C 10 0 !T?-r".—T 10 — _ . 0 ^ ^ >s /> 10 i « g J 5 11 y u ^ -3 u - — JJ < < a. - i~ --5 — a. -A — - i c - * £. a. — a: ZONE Recognitum Harbledownense Varians Arnouldi Arnouldi Figure 3-11 Biostratigraphy of Section M on Maude Island. BIOSTRATIGRAPHY AND BIOCHRONOLOGY 32 quarry also yielded well preserved specimens of Arnioceras arnouldi. The section can be assigned to the A r n o u l d i Zone. M E T R I C M A I N R O A D C U T ( S E C T I O N R ) Ammoni tes were collected from a roadcut by S. TAITE. A typ i ca l l y thick sandstone beds of the Sandilands Format ion yielded Arnioceras arnouldi and A. cf. oppeli, indicative of the A r n o u l d i Zone, along wi th an unusual benthic assemblage consisting of gastropods and coral fragments. 3.3.5 KUNGA ISLAND N O R T H S H O R E ( S E C T I O N S) A long and generally narrow inter t idal bench and shoreline exposure is cut by numerous dykes and faults; a few intervals are covered (F ig . 3-12). Th i s is the type section of the K u n g a Format ion of SUTHERLAND BROWN (1968), where the Sadler, Pe r i l and the lower part of the Sandilands Formations are also represented. Fau l t s caused small scale repetitions and/or omissions in the section, but do not upset the ammonite succession. A cumulat ive thickness of over 400 m of uppermost Hettangian to Sinemurian rocks was measured. The beds under lying the Canadensis Zone d id not yield macrofossils but a Late Hettangian age is proved by radiolarians ( E . S . CARTER, pers. comm., 1990). The Canadensis Zone together wi th the next higher four zones are well developed. The Harbledownense Zone is truncated by a massive dyke forming a point at the southeastern end of the section. S O U T H S H O R E ( S E C T I O N T ) Exposures on the south shore of the island are similar to those on the nor th shore. The Sinemurian strata of the "Coroniceras" Zone are separated from the Upper Hettangian by a covered interval; the Canadensis Zone is omi t ted . The couplet of the A r n o u l d i and Var ians Zones is repeated, possibly also encompassing several minor tectonic breaks (F ig . 3-13). The upper part of the Harbledownense Zone is BIOSTRATIGRAPHY AND BIOCHRONOLOGY 33 SANDILANDS o < < < • J : < | _ < : : i ' ; : 11 < < < T T 9> • mrnrn I J.I: : I o K J e co o o CO Ol o • 1 : 1 '• 1 : 1 ' • • ' . i . ' . ' . " t i l l • •• ' 1 t ^ . , i ' j \ i,' • ' • Mi?™ ri'lV:':' : i :; I;I l i " ' r-» 0 • n u 3 SJ C It n o n it p 3 0 c < 3 I -t (t a. o S 3 FORMATION THICKNESS LITHOLOGY LEVEL Vermiceras sp. indet. Badouxia canadensis Angulaticeras sp. Badouxia columbiae Eolytoceras c i . tasekoi Sulciferites ? sp. Juraphyllites cf. transyivanicus Juraphyllites sp. indet. Arnioceras arnouldi Arnioceras sp. indet. Arnioceras cf. speciosum Arnioceras ex gr. ceratitoides Asteroceras all", margarita Asteroceras sp. indet. Arnioceras cf. oppeli Asteroceras cf. saltrirnsc Epophioceras aff. carinalum Plesechioceras ? aklavikense Tetraspidoceras paciiicum Plesechioceras ? harbledownense Paltechioceras sp. indet. Paltechioceras aif. boehmi N o Z Figure 3-12 Biostratigraphy of Section S on Kunga Island. BIOSTRATIGRAPHY AND BIOCHRONOLOGY 34 SANDILANDS TT e FORMATION THICKNESS 'iV;1 • r . •JJ-.r.-i MM' I II I I.Mi ! I I ! i : : : | | • v . ; . 1 V;' v. I l» 1 1111 I I LITHOLOGY T T LEVEL n c > 3 < '5' 3 3 O < I rt Q. O ? 3 rt 3 3 3 rt O C era 3_ C 3 Coroniceras ? sp. Angulaticeras cf. ventricosum Juraphyliites cf. transvlvanicum luraphyliites sp. indet. Arnioceras sp. indet. Arnioceras ex ur. ceratitoides Arnioceras arnouldi Arnioceras miserabiic Arnioceras cf. oppeii Arnioceras cf. densicosta Asteroceras aff. margarita Phyiloceras spp. Arnioceras ex gr. mendax Arnioceras cf. speciosum Adnethiceras cf. adnethicum Asteroceras cf. saltricnsc Asteroceras sp. indet Gieviceras sp. indet. Plesechioceras yakounense Plesechioceras ? harbiedowtienst-Posidonotis semiplicata luraphyliites afl. nardii Crucilobiceras ? sp. indet. Phricodoceras ? sp. Tropidoceras sp. N o-Z m Figure 3-13 Biostratigraphy of Section T on Kunga Island. BIOSTRATIGRAPHY AND BIOCHRONOLOGY 35 affected by contact metamorphism by two major dykes and therefore devoid of interpretable fossils. The Recognitum Zone is proved by sporadic ammonoids and Posidonotis semvplicata and the contact with the Imlayi Zone is apparently conformable. A substantial Lower Pliensbachian section extends towards the eastern tip of the island (SMITH et al., 1990). 3.4 L O C A L CORRELATION AND ITS GEOLOGICAL IMPLICATIONS Exposures of the Sandilands Formation are widespread throughout the islands but they typically Figure 3-14 Biostratigraphic correlation between the studied uppermost Hettangian to lowermost Pliensbachian section of the Queen Charlotte Islands. BIOSTRATIGRAPHY AND BIOCHRONOLOGY 36 consist of faulted blocks juxtaposed with each other or bounded by other rock units. Because of the lack of laterally persistent marker beds biostratigraphy is the most useful correlation tool. Correlation of the measured sections is illustrated on Fig. 3-14. Although the assignment to certain zones is almost always unambiguous, the placement of parts of sections within the zones is in some cases tentative. Such a high resolution correlation will provide a valuable time-frame for any future sedimentological study of the Sandilands Formation. KENNECOTT POINT NW 35 YAKOUN RIVER 32 35 Reco Harbledownense Canadensis KUNGA ISLAND 36 49 45 S E Figure 3-15 Lateral thickness changes of selected zones in measured sections. Thickness is indicated in meters. BIOSTRATIGRAPHY AND BIOCHRONOLOGY 37 3.4.1 THICKNESS ESTIMATES.AND TRENDS The Sinemurian sedimentary succession is most completely preserved on K u n g a Island but even there it is pieced together from tectonically dis turbed fragments present in Sections S and T . St ructura l complexity of the sections frequently results in repetitions or losses, many of them small enough to be beyond the l imi t of biostratigraphic resolution. Thus the to ta l thickness of the uppermost Het tangian to lowermost Pl iensbachian rocks can only be estimated. After matching the two sections a m i n i m u m thickness of 310 m was calculated, assuming that all the proven and suspected faults duplicate parts of the sections unless proven otherwise by the fauna. A m a x i m u m estimate from the opposing premise is 490 m. T o suggest 385 m as a reasonable value wi th in these brackets remains somewhat subjective relying on weighing the likelihood of biostratigraphic and field relationship of the faulted segments. T o analyze lateral changes of thickness specific zones were traced from section to section. For a reliable measurement a zone must be present in a s t ructural ly simple setting wi th both its lower and upper boundaries well defined. O n l y in a few places are these cri teria met (F ig . 3-15). Apparen t ly the thickness increases consistently from northwest to southeast between 10 to 40%. Together wi th the more sudden east-west lithofacies changes discussed in chapter 2.2.2, this pat tern may suggest that the source area of the distal turbidites of the Sandilands Format ion la id to the southwest. T o draw the boundary between the two formations is often difficult due to the gradational nature of the contact. The t ransi t ion from the more indurated, flaggy Sandilands Fo rma t ion to the recessive, fissile Ghost Creek Fo rma t ion usually occurs w i th in an interval of several meters. However, the tuffaceous and minor graded sandstone interbeds characteristic of the Sandilands Format ion infrequently recur in the lower part of the Ghost Creek Format ion . 3.4.2 THE CONTACT OF THE SANDILANDS AND GHOST CREEK FORMATIONS BIOSTRATIGRAPHY AND BIOCHRONOLOGY 38 NW SE Y a k o u n River W h i t e a v e s i I m l a y i R e c o g n i t u m H a r b l e d o w n e n s e bJ UJ m o o X m. Q z Q Z < cn M a u d e I s l a n d •tri-er: o I— CO o CO Q z Q Z < CO K u n g a I s land O LJJ X or 2.9.2. CO Z < _J O Z < t n -Figure 3-16 Diachronism at the contact of the Sandilands and Ghost Creek Formations. The resolution of our ammonite biostratigraphy is sufficient to demonstrate the diachronous nature of the contact (SMITH et al., 1990; TIPPER et al., 1991). The age of the contact is constrained in three sections (Fig. 3-16). At Yakoun River (Section H) the transition occurs in the lower part of the Recognitum Zone, on Maude Island (Section M) in the upper part of the Recognitum Zone, whereas on Kunga Island (Section T) it is found near the base of the Whiteavesi Zone (which overlies the Imlayi Zone). 3.5 CORRELATION AND BIOCHRONOLOGY In this section a correlation of the Queen Charlotte zones with other areas in western North America and possibilities of intercontinental correlation with the Northwest European and Mediterranean Provinces BIOSTRATIGRAPHY AND BIOCHRONOLOGY 39 (Fig. 3-17), South America, and other parts of the world are discussed. The problem of the Sinemurian stage boundaries in the Queen Charlotte Islands is also addressed. 3.5.1 The Canadensis Zone and the Hettangian/Sinemurian boundary The Canadensis Zone of FREBOLD (1967) is defined by its diverse assemblage and particularly abundant index ammonite. It is widespread and easily recognizable in many areas (Alaska: IMLAY, 1981; STAGE NW EUROPE QUEEN CHARLOTTE ISLANDS NORTHERN ALPS STAGE ZONE SUBZONE CL JAMESON 1 JAMESONI IMLAYI BREVISPINA POLYMORPHUS TAYLORI RECOGNITUM SINEMURIAN RARICOSTATUM APLANATUM 1 » L__ \ _ / \_7 I l l l W 1V1 HARBLEDOWNENSE SINEMURIAN MACDONELLI SINEMURIAN RARICOSTATUM SINEMURIAN DENSINODULUM SINEMURIAN OXYNOTUM OXYNOTUM SINEMURIAN SIMPSONI SINEMURIAN OBTUSUM DENOTATUS VARIANS SINEMURIAN STELLARE SINEMURIAN OBTUSUM SINEMURIAN TURNERI BIRCHI ARNOULDI SINEMURIAN BROOKI SINEMURIAN SEMICOSTATUM SAUZEANUM SINEMURIAN SCIPIONIANUM SINEMURIAN REYNESI SINEMURIAN BUCKLANDI BUCKLANDI "CORONICERAS" SINEMURIAN ROTIFORME ROTIFORME SINEMURIAN CONYBEARI CANADENSIS MARMOREUS X ANGULATA COMPLANATA EXTRANODOSA MEGASTOMA Figure 3-17 Approximate correlation of the proposed latest Hettangian to earliest Pliensbachian ammonite assemblage zones with the northwest European and Alpine zonations. (Northwest European zonation after DEAN et al., 1961; Alpine Zones after WAHNER, 1886). BIOSTRATIGRAPHY AND BIOCHRONOLOGY 40 Br i t i sh C o l u m b i a : Telegraph Creek area, FREBOLD, 1964, U n u k River , Quesnel Lake, FREBOLD and TIPPER, 1970, Taseko Lakes area, FREBOLD, 1951, 1967; Nevada: GUEX and TAYLOR, 1976; Oregon: TAYLOR, in prep.). T h u s it seems to be a val id chronozone on a regional scale. A twofold subdivis ion already noted by FREBOLD (1967) and confirmed by TAYLOR (1990) as well as by our results may warrant the erection of subzones after a revision of the type sections near Tyaugh ton Creek. In Nevada an assemblage subjacent to the Canadensis Zone recorded by GUEX and TAYLOR (1976) as Zone B and by TAYLOR (in prep.) as Oregonensis Zone, contains elements (Badouxia oregonensis, Metophioceras aff. rursicostatum, Eolytoceras guexi) recognized in the lower part of the Canadensis Zone in the Queen Charlot te Islands. The two most characteristic genera of the Canadensis Zone, Badouxia and Eolytoceras, are restricted in dis t r ibut ion to the Circum-Paci f ic and western N o r t h Amer ica , respectively. Species of Vermiceras, Metophioceras as well as schlotheimiids provide correlation wi th Europe. The T e t h y a n character of the fauna allows comparison wi th the Medi terranean Marmoreus Zone of WAHNER (1886), as pointed out by GUEX and TAYLOR (1976). Vermiceras ex gr. coregonense, V. cf. supraspiratum, Sulciferites marmoreus and S. cf. trapezoidalis establish ties to that zone, which is of condensed lithology at the A l p i n e localities. The correlation of the Marmoreus Zone wi th the s tandard Northwest European zonation is a controversial subject. GUEX and TAYLOR (1976) argued for allocating most or al l of it to the Sinemurian based on reported occurrences of Sulciferites marmoreus and accompanying schlotheimiids from the Conybear i Subzone. Th i s view was debated by BLOOS (1983), who showed new evidence of this species originating in the Depressa Subzone (Angula ta Zone, Upper Hettangian) (BLOOS, 1988). DEAN et al . (1961) defined the base of the earliest Sinemurian Conybear i Subzone by the first appearance of Metophioceras. BLOOS (1989) reviewed the alternatives such as to draw the boundary at the base of the Marmoreus Zone or at the contact of the Complana t a and Depressa subzones. He retained the t radi t ional view wi th the necessary modification of the definition of the Conybear i Subzone in order to conform wi th the assemblage zone concept, since forerunners of Metophioceras have been reported from the Upper Het tangian (e.g. BLOOS, 1983). Based on the present study the following comments can be made: BIOSTRATIGRAPHY AND BIOCHRONOLOGY 41 - Beds immediately subjacent to the Canadensis Zone yielded Alsatites cf. proaries (NEUMAYR) (PI. 16, fig. 5), documented by WAHNER (1886) from the A l p i n e Megastoma Zone below the Marmoreus Zone. - The assemblage of Vermiceras cf. supraspiratum, V. ex gr. coregonense, Sulciferites marmoreus, and S. cf. trapezoidalis in the Canadensis Zone allows good comparison wi th the Te thyan Marmoreus Zone. - The incoming of Metophioceras aff. rotarium and Metophioceras spp. in the upper part of the Canadensis Zone suggests correlation w i t h the Conybear i Subzone of Northwest Europe. - The first appearance of Coroniceras ? spp. and Arnioceras sp. (characteristic of the B u c k l a n d i Subzone in Europe) is s trat igraphical ly only approx. 10 m above the last occurrence of Badouxia canadensis. Consequently, the He t tang ian /S inemur ian boundary (sensu DEAN et al . , 1961 and BLOOS, 1989) should be placed wi th in the Canadensis Zone. The best approximation is to tie it to the incoming of Metophioceras aff. rotarium and Metophioceras spp. which nearly coincides wi th the first appearance of Badouxia columbiae. S imi lar views are expressed by TAYLOR (1990) based on data from Nevada. The Ci rcum-Pac i f ic d is t r ibut ion of Badouxia canadensis permits correlation wi th South A m e r i c a and northeast Siberia. In A r g e n t i n a this zone was recognized by RlCCARDI et al . (1989) based on Badouxia canadensis, Metophioceras cf. rursicostatum, Sulciferites cf. marmoreum, and Vermiceras sp., very close to our interpretat ion. These authors s imilar ly correlated it wi th the upper part of the Angu la t a and lower part of the B u c k l a n d i Zones (RlCCARDI et a l , 1990, Char t 1). Other South A m e r i c a n records are more controversial. Badouxia canadensis was recognized in Chi le by HlLLEBRANDT (1981, 1987, 1991) and QUINZIO SINN (1987). Their correlation wi th the s tandard Liasicus Zone (Midd le Hettangian) is based on the cooccurrence wi th Alsatites cf. platystoma which is probably a misidentified Vermiceras (Paracaloceras) as pointed out by TAYLOR (1990 and in prep.). Similar forms are known from the Canadensis Zone of Nevada (TAYLOR, 1990). F r o m northeast Siber ia REPIN (1977) reported "Psiloceras" ("Franziceras") canadense from a unit s imi lar ly correlated wi th the Liasicus Zone on the basis of Waehneroceras. Alsatites cf. coregonensis and Discamphiceras sp. are also found in this assemblage (REPIN, 1988) support ing correlation wi th the BIOSTRATIGRAPHY AND BIOCHRONOLOGY 42 Canadensis Zone. A s Vermiceras coregonense has been found nowhere else as low as the Liasicus Zone, the age assignment of the Siberian assemblage may need revision. 3.5.2 The "Coroniceras" Zone This zone is so poorly represented in the Queen Char lot te Islands that its separation from the subjacent and superjacent units can only be defended from a regional perspective. R i c h ammonite assemblages are known between the Canadensis Zone and beds wi th abundant Arnioceras from the Taseko Lakes area (lower part of Arietites -beds of FREBOLD, 1951) and from Nevada (Zone C of TAYLOR, 1986; T r igona tum and Involu tum Zones of TAYLOR, in prep.). Coroniceras is the most abundant and diverse genus in both cases. Its much reduced frequency in the Queen Char lot te Islands may be explained by ecological and facies factors, as a deeper water basinal environment was not preferred by this genus (WESTERMANN, 1990). In Europe Coroniceras is far more abundant in the. inner shelf facies of the Northwest European Province than in the Medi ter ranean localities. The scarcity of Coroniceras ? spp. in the s tudy area permits only gross correlation wi th the upper part of the standard B u c k l a n d i Zone and wi th the A l p i n e Rotiforme Zone. 3.5.3 The Arnouldi Zone Thi s zone is recognized by the preponderance of different species of Arnioceras. Similar Arnwceras-dominated faunas are known from several areas in western N o r t h Amer ica , such as A l a s k a (IMLAY, 1981), Y u k o n and Br i t i sh C o l u m b i a (localities and references listed in detail in FREBOLD and TIPPER, 1970), and Nevada (HALLAM, 1965, SMITH, 1981). I n some cases Arnioceras species ( including those of the synonymous Arniotites) need to be restudied before their ranges can be compared. ' Arnioceras in Northwest Europe ranges from the B u c k l a n d i Subzone through the O b t u s u m Zone and it is par t icular ly abundant in the Semicosta tum Zone. Subzonal subdivisions in this and the superjacent BIOSTRATIGRAPHY AND BIOCHRONOLOGY 43 Turne r i Zone, however, are based on species of other genera such as Coroniceras, Agassiceras, Euagassiceras, Caemsites, and Microderoceras, unknown from the study area except for Coroniceras. T h u s the A r n o u l d i Zone can be correlated broadly wi th the standard Semicostatum and Turne r i zones but the dis t inct ion of equivalents of these Northwest European zones in the local succession is not possible. Faunas correlative wi th the Turne r i Zone are not known in Nor th A m e r i c a wi th the possible exception of the Taseko Lakes area (H.W. TIPPER, pers. comm.) . Th i s zone is not well characterized even in continetal Europe (BLOOS, 1984b) and it is difficult to prove in the Mediterranean faunas (GECZY, 1972). The A r n o u l d i Zone compares favorably wi th the ^rnioceras-dominated Medi terranean assemblages such as the Assemblage F and G of BRAGA et al . (1984b) from Spain. The stratigraphic significance of addit ional , rare elements (Adnethiceras cf. adnethicum, Audaxlytoceras cf. audax, Tragolytoceras ? sp., Angulaticeras spezianum) is poorly understood. C o m m o n Arnioceras faunas in the Circum-Paci f ic region (such as the West and Southwest Pacific localities listed by SATO, 1957, 1975) provide further possibilities for correlation of the A r n o u l d i Zone. In South A m e r i c a the equivalent of the Semicostatum Zone is recognized (HlLLEBRANDT, 1987 and references therein) but the record of the T u r n e r i Zone is scarce. 3.5.4 The Varians Zone The assemblage of Asteroceras, Arnioceras, and Epophioceras characterizing this zone is not widespread in N o r t h A m e r i c a . IMLAY (1980) does not mention it from the conterminous U n i t e d States and no record exists from A l a s k a (IMLAY, 1981). SMITH (1981), however, reports Epophioceras and Asteroceras (Eparietites) f rom Nevada assigning it to the upper part of his Ceratitoides Zone. Asteroceras is known from different localities in B r i t i s h C o l u m b i a (FREBOLD and TIPPER, 1970). Arctoasteroceras jeletzkyi f rom the Canadian A r c t i c (FREBOLD, 1960) is closely comparable to Asteroceras varians in lateral view. The Var ians Zone can be correlated wi th the standard O b t u s u m Zone based on concurrent generic ranges despite their different species content. It shows an even greater s imilar i ty to Medi terranean faunas BIOSTRATIGRAPHY AND BIOCHRONOLOGY 44 equivalent of the O b t u s u m Zone as out l ined from Hungary (GECZY, 1971, 1972) and Spain (Assemblage H : BRAGA et al., 1984b). The record from Italy is summarized by DONOVAN (1990) who attempts to prove the presence of standard subzones without support ing local stratigraphic evidence. Correlat ion is possible w i t h South A m e r i c a n faunas as HlLLEBRANDT (1987) recognizes the equivalent of the O b t u s u m Zone based on Epophioceras and Asteroceras from Chi le and Pe ru (see references in RlCCARDI et al. , 1990). Ano the r Epophioceras faunula is known from Argen t ina (RlCCARDI et al. , 1989). 3.5.5 The Harbledownense Zone This zone is characterized by the abundance of echioceratids accompanied by oxynoticeratids in its basal part . Echioceratids are common in A l a s k a (IMLAY, 1981) and i n the Taseko Lakes area ( H . W . TIPPER, pers. comm). The record from Harbledown Island (CRICKMAY, 1928, TIPPER, 1977) is similar to that of the Queen Charlot te Islands. F r o m Nevada SMITH (1981) documented a r ich assemblage of echioceratids assigned to his Harbledownense and Rothp le tz i Zones. The Harbledownense Zone in the Queen Char lot te Islands is drawn in a different sense, as no cooccurrence of Plesechioceras ? harbledownense w i th Asteroceras has been found. SMITH'S (1981) Harbledownense Zone, correlated w i t h the uppermost T u r n e r i and O b t u s u m Zones of the standard zonation, is considered close to our Var ians Zone. The Harbledownense Zone as understood here is translated to include SMITH'S (1981) Ro thp le t z i Zone. A s SMITH'S (1981) local zonal scheme remains unpublished, this does not violate the law of pr ior i ty and should not lead to confusion. The base of the Harbledownense Zone is marked by the first appearance of oxynoticeratids and thus can be correlated wi th the s tandard O x y n o t u m Zone. In Northwest Europe Oxynoticeras simpsoni is the index of its lower subzone. The earliest echioceratids in the Queen Char lot te Islands can be assigned to Plesechioceras (P. yakounense, P. ? harbledownense, P. ? cf. aklavikense) which in Europe first appears in the basal subzone of the Rar icos ta tum Zone (DOMMERGUES, 1982). Palaeoechioceras, which is the first echioceratid to appear in Europe in the O x y n o t u m Zone, is not known from the study area (although it is recorded from Nevada by SMITH, 1981). Paltechioceras, which in Europe ranges through the Rar icos ta tum BIOSTRATIGRAPHY AND BIOCHRONOLOGY 45 Zone, w i t h peak abundance in its highest subzone, here overlaps wi th Plesechioceras ? harbledownense. The lack of raricostate forms (Echioceras) and Leptechioceras is a feature in common wi th Medi terranean faunas (e.g. DONOVAN, 1990). A m o n g the species of Paltechioceras, P. boehmi is known to range from the Raricostatoides to the A p l a n a t u m Subzone in Europe (DOMMERGUES and MEISTER, 1989, GETTY, 1973), whereas P. romanicum is allocated to the highest Sinemurian (BREMER, 1965). Plesechioceras may offer an interesting correlation wi th faunas of the Canadian A r c t i c (Echioceras aklavikense, E. arcticum of FREBOLD, 1960 and 1975) through Br i t i sh C o l u m b i a to South Amer ica , where -HlLLEBRANDT (1987) reports Plesechioceras arcticum cooccurring wi th forms transi t ional between Plesechioceras and Palaeoechioceras. 3.5.6 The Recognitum Zone and the Sinemurian /Pliensbachian boundary The Recogni tum Zone yielded a dist inctive assemblage between the last occurrence of Paltechioceras and the base of Imlayi Zone, the basal uni t of the Pl iensbachian as defined by SMITH et al . (1988), who believed there was a consistently unfossiliferous interval between those two levels. The Rar icos ta tum Zone in Europe corresponds to the range of Paltechioceras (DEAN et al. , 1961). SMITH et al . (1988) presented compell ing evidence for the correlation of the base of Imlayi Zone wi th that of the s tandard Jamesoni Zone. Thus the understanding of the Recogn i tum Zone bears on the definition of the S inemur ian /Pl iensbachian boundary in the Queen Char lo t te Islands. T h i s is the first detailed record of the Recogni tum Zone assemblage, al though a biostratigraphic unit marked by Entolium balteatum was already noted by CAMERON and TIPPER (1985). Th i s abundant bivalve (now revised as Posidonotis semiplicata) is a characteristic element of the fauna. Its biostratigraphic significance is proved locally but questionable regionally. However, there are several examples of short ranging pelagic bivalves such as the Triassic Halobia or Monotis. IMLAY (1981) documented Entolium ? semiplicata cooccurring wi th Paltechioceras ? sp. and Crucilobiceras cf. crucilobatum from the Wrange l l M t n s . of A l a s k a , whereas CRICKMAY (1928) described Entolium balteatum found together w i t h Melanhippites BIOSTRATIGRAPHY AND BIOCHRONOLOGY 46 ? sp. (probably an echioceratid) from Harbledown Island. Whethe r the range of echioceratids extends higher or this bivalve appears lower in these other localities cannot be decided. Crucilobiceras ? sp. cannot define the stage boundary as the genus first appears in the basal Rar icos ta tum Zone in northwest Europe ( D E A N et al . , 1961) and ranges up to the Jamesoni Zone ( S C H L A T T E R , 1980). The Italian occurrences of Tetraspidoceras recognitum (see synonymy) are poorly dated. The genus is well represented in the Upper Sinemurian of Italy ( F E R R E T T I , 1975, PALLINI, 1986, D O N O V A N , 1990). Different species from other Medi terranean localities in Hungary suggest a Jamesoni Zone age ( G E C Z Y , 1976). Another species of the genus, Tetraspidoceras quadrarmatum is thought to characterize the extreme base of the Pl iensbachian in Northwest Europe ( H O F F M A N N , 1982, D O M M E R G U E S and MEISTER, 1989). The two rare oxynoticeratids originating from the Recogni tum Zone, though not allowing unambiguous correlation, have closer affinities wi th the Pl iensbachian. The Radstockiceras numismale group occurs in the basal Jamesoni Zone in the type area of the stage ( S C H L A T T E R , 1977, 1980), where the Upper Sinemurian is missing. B R E M E R (1965) also found it in the Jamesoni Zone of A n a t o l i a above the last Paltechioceras. In the Queen Char lo t te Islands Juraphyllites aff. nardii occurs abundant ly in certain beds. However, it is not known elsewhere in N o r t h Amer i ca . A l t h o u g h Juraphyllites species are generally long ranging, their derivative Tragophylloceras - to which the present species can be a connecting l ink - includes the zonal index for the standard Ibex Zone. A s follows from the above arguments, the status of the Recogni tum Zone and its relation to the S inemur ian /Pl iensbachian boundary cannot be satisfactorily settled yet. However, the present evidence tends to favour its allocation at least par t ia l ly to the earliest Pl iensbachian. P A L E O B I O G E O G R A P H Y 47 C H A P T E R 4 P A L E O B I O G E O G R A P H Y 4.1 I N T R O D U C T I O N Paleobiogeographic studies furthered the understanding of the N o r t h Amer i can Cordi l le ra as a collage of several allochthonous terranes (CONEY et al. , 1980). Since TOZER (1970) and MONGER and ROSS (1971) first presented evidence of faunal anomalies support ing major displacement of Cordi l le ran crustal fragments, various fossil groups of Late Paleozoic-Mesozoic age have been investigated from a paleobiogeographic perspective, contr ibut ing to our knowledge of the geological history of the Cord i l l e ra (see HALLAM, 1986 and SMITH, 1989 for reviews). Fauna l data from different areas can be compared to assess their affinities and to detect provincia l ism. B y this method paleolat i tudinal and longi tudinal constraints on the relative position of terranes and the craton are assessed. Jurassic ammonite provincia l i sm was recognized in Europe more than a century ago (NEUMAYR, 1883). Ammoni t e s are inferior to benthonic organisms for a paleobiogeographic reconstruction by vir tue of their nektonic mode of life and great dispersal abi l i ty . Th i s disadvantage is offset as they are widely available in different terranes, thoroughly studied worldwide, and have received considerable attention due to their biostratographic significance. The cosmopolitan nature of most Sinemurian ammonites has long been recognized (e.g. ARKELL, 1956). Y e t beside the abundant t ruly pandemic genera (Coroniceras, Arnioceras, Asteroceras, Paltechioceras, etc.), there are a number of genera wi th more restricted geographic d is t r ibut ion providing a basis for dis t inct ion of biogeographic provinces. 4.2 E A R L I E R N O R T H A M E R I C A N S Y N T H E S E S A comprehensive treatment of the paleobiogeography of Jurassic ammonite faunas of N o r t h A m e r i c a is given by TAYLOR et al . (1984). Thei r terminology is followed here dist inguishing the Boreal , Te thyan , and East Pacific Realms. The latter, comprising the Nor th Cordi l le ran Region, was subdivided into the P A L E O B I O G E O G R A P H Y 48 Athabascan and Shoshonean Provinces, of which only the first existed during the Sinemurian time. T w o informally used terms are Pandemic , denoting worldwide dis t r ibut ion, and Pacific, referring to occurrences restricted to the Ci rcum-Pac i f ic margin. T h e authors recognized several Te thyan indicator genera from different N o r t h A m e r i c a n localities, while the Athabascan Province was characterized by Eolytoceras and Arctoasteroceras only. The Pl iensbachian ammonite faunas have received more at tention in the past several years and a model emerging from studies of SMITH (1983) and SMITH and TIPPER (1986, 1989) postulated a marine seaway (the Hispanic Corr idor) to explain the d is t r ibut ion of common elements of the Western Tethys and the East Pacific and proposed increasing nor thward displacement of St ik in ia , Quesnellia, and Wrangel l ia terranes. Sinemurian faunas can be used to test the probabi l i ty of extrapolation of this hypothesis (BRAGA et a l , 1989). 4.3 A S S E S S M E N T O F T H E Q U E E N C H A R L O T T E I S L A N D S F A U N A W i t h its 61 ammonite species allocated to 27 genera, the latest Het tangian to earliest Pliensbachian fauna from the Queen Char lot te Islands is among the most diverse of its age in N o r t h Amer ica , matched only by that of the Taseko Lakes area and Nevada . Divers i ty is a result of niche par t i t ioning related to environmental s tabi l i ty and tends to be controlled by paleolatitude (HALLAM, 1973). Nor th Amer ican craton-bound faunas provide supportive evidence as diversity increases from nor th to south (Arc t i c Islands: 7 genera from incomplete Sinemurian (FREBOLD, 1975); Fernie Bas in : 7 genera from incomplete Sinemurian (FREBOLD, 1969, HALL, 1984, 1987); Nevada: 26 genera (SMITH, 1981, TAYLOR, 1986, 1990, and in prep.)). The Queen Char lo t te Islands, now at comparable lat i tude wi th the Fernie Bas in but surpassing, it in diversity, best agrees wi th the Nevadan record thus suggesting significant nor thward displacement. Divers i ty , d is t r ibut ion patterns, and faunal s imi lar i ty can be studied at different taxonomic levels. The higher resolution of species level is commonly offset by inherent problems of species in paleontology and bias due to uneven sampling. The most common practice is to use the genus as basic taxonomic unit for PALEOBIOGEOGRAPHY 49 Figure 4-1 Histogram of the number of genera with different distribution pattern. paleobiogeography. Family level offers less contrast for distinguishing provinces but it is commonly used in global studies of broader scope in time and fossil phyla. The faunal affinities of the Queen Charlotte Islands are analyzed in these levels using the data presented in the distribution section under each taxon in Chapter 6. All the families of Sinemurian Ammonitina are cosmopolitan in distribution but some families of Lytoceratina and Phylloceratina may serve as indicators of the Tethyan Realm. Among these the Derolytoceratidae, Analytoceratidae, and possibly the Pleuracanthitidae are recorded from the Queen Charlotte Islands. A survey of the 27 genera represented (Fig. 4-1) shows that most are pandemic, but several have Tethyan distribution (Juraphyllites, Adnethiceras, Tragolytoceras, Audaxlytoceras, Ectocentntes, Sunnsites, Hyp asteroceras, P aroxynoticeras). Although the number of Tethyan indicator genera is significant, some are identified with uncertainty and most are represented by only a few individuals. The main exception is the PALEOBIOGEOGRAPHY 50 NUMBER OF SPECIES 30 20 -10 -PANDEMIC TETHYAN ATHABASCAN EAST PACIFIC PACIFIC Figure 4-2 Histogram of the number of species with different distribution pattern. rather abundant Juraphyllites. Eolytoceras is a genus found so far only in the Athabascan Province, whereas Badouxia shows a Pacific distribution (TAYLOR et al, 1984). The results of a similar approach taken at species level are shown on Fig. 4-2. An interesting feature is that the Athabascan Province can be better delineated by endemic species of mainly Canadensis and Harbledownense Zone age. The Tethyan influence is clearly demonstrated by a large number of species. In addition to the ammonites, the bivalve Posidonotis semiplicata provides another example of an Athabascan species of a Tethyan genus (DAMBORENEA, 1989). Illustrative examples of different species distributions are plotted on Fig. 4-3. Combining biochronological results with the paleobio-geographic analysis, temporal patterns of provinciality may emerge. Tables 4-1 and 4-2 reveal that pandemic elements form a majority and the Tethyan influence is significant throughout the entire Sinemurian. Athabascan together with East Pacific PALEOBIOGEOGRAPHY 51 V Eolytoceras tasekoi: ATHABASCAN • Metophioceras rurslcostatum: EAST PACIFIC T Badouxia canadensis: PACIRC • Vermiceras coregonense: TETHYAN Figure 4-3 Examples of species with different paleobiogeographic distribution. PALEOBIOGEOGRAPHY 52 P R O V I N C E - * | Z O N E A T H A -B A S C A N E A S T P A C I F I C P A C I F I C T E T H Y A N P A N -D E M I C Recogni tum - - - 3 50% 3 50% Harbledownense - - - - 5 100% Var ians - - - 1 25% 3 75% A r n o u l d i - - - 4 66.7% 2 33.3% "Coroniceras" - - - 1 20% 4 80% Canadensis 1 9.1% - 1 9.1% 3 27.3% 6 54.5% T a b l e 4-1 Tempora l pattern of genus level provincia l ism in the Sinemurian ammonite fauna of the Queen Charlot te Islands. P R O V I N C E - . J Z O N E A T H A -B A S C A N E A S T P A C I F I C P A C I F I C T E T H Y A N P A N -D E M I C Recogni tum 1 16.7% - - 3 50% 2 33.3% Harbledownense 3 . 27.3% 1 9.1% - 2 18.2% 5 45.5% Var ians - - - 4 44.4% 5 55.6% A r n o u l d i - - - 6 50% 6 50% "Coroniceras" - - - 1 20% 4 80% Canadensis 7 30.4% 1 4.4% 1 4.4% 7 30.4% 7 30.4% T a b l e 4-2 Tempora l pattern of species level provincia l ism in the Sinemurian ammonite fauna of the Queen Charlot te Islands. PALEOBIOGEOGRAPHY 53 provinc ia l i sm was strongest in the Canadensis Zone and also traceable in the Late Sinemurian-earliest Pl iensbachian. 4.4 MODELS EXPLAINING T E T H Y A N FAUNAS IN T H E CORDILLERA In the past two decades an impressive inventory of Te thyan fossils occuring in the Cordi l le ra has been built (e.g. NEWTON, 1988). Pre-Jurassic records from Wrange l l i a include Late Triassic corals from Vancouver Island (STANLEY, 1988), and a Monotis assemblage indicative of low paleolatitude (TOZER, 1982, SlLBERLING, 1985) from the Per i l Fo rma t ion of the Queen Char lo t te Islands found together wi th the hydrozoan Heterastridium (CARTER et al. , 1989). There is mount ing evidence of Te thyan indicator Sinemurian ammonites found in various Cordi l le ran localities. A p a r t from those reported from the Queen Charlot te Islands, the Taseko Lakes area and Nevadan localities yielded Canavarites, Pseudotropites, Pseudaetomoceras, Paradasyceras, and Tmaegoceras (TAYLOR, 1990, in prep., D . TAYLOR and H . W . TIPPER, pers. comm.). Three different models have been proposed to explain the occurrences of Te thyan fossils in the Amer i can Cordi l lera . The simplest model developed upon mainly pre-Jurassic data calls for pantropic dis t r ibut ion facilitated by circum-equatorial currents to account for common elements of Te thyan and East Pacific fossil biotas (NEWTON, 1988). Secondly, the tectonic dislocation model postulates oceanic plateaus or microcontinents in the ancient West Pacific as endemic centers wi th T e t h y a n affinities later dismembered and swept across the Pacific by long-range tectonic dislocation due to sea-floor spreading (STEVENS, 1983, STANLEY and YANCEY, 1990). F ina l ly , from the E a r l y Jurassic onward, the faunal exchange between the Western Tethys and East Pacific may have been facilitated by a marine seaway termed Hispanic Corr idor (SMITH, 1983, SMITH and TIPPER, 1986), a forerunner of the Cent ra l A t l a n t i c which was undoubtedly open by Late Jurassic time (SHERIDAN et a l , 1982). Our ammonite data from the Queen Char lot te Islands do not support convincingly the long-range longi tudinal tectonic displacement hypothesis. Badouxia is the only genus of which B. canadensis is the only PALEOBIOGEOGRAPHY 54 species found on both sides of the Pacific, whereas a series of other species show Athabascan or East Pacific dis t r ibut ion imp ly ing only a l imi ted amount of longi tudinal displacement. T o endorse the pantropical dispersal, in accord wi th NEWTON's (1988) model, an eastward diversity attenuation of T e t h y a n forms from the Eastern Te thys to the East Pacific has to be demonstrated. The existing record from the Eastern Te thyan region (e.g. Himalaya : DlENER, 1908, T imor : ROTHPLETZ, 1882, KRUMBECK, 1923, Japan: SATO, 1954) is scarce and thus inadequate for this purpose. In fact the diversity of some N o r t h A m e r i c a n faunas far exceeds that from the Eastern Te thyan areas thus contradict ing the pantropical model but this is certainly part ly due to the lack of comprehensive studies from that region. Based purely on the faunal record, i.e. the s imilar i ty of Nor th Amer ican and Western Te thyan faunas, the extension of the Hispanic Corr idor back to the Sinemurian time is feasible, al though support ing geological evidence is weak (SCHMIDT-EFFING, 1980). Regardless which model is favoured, the high ratio of pandemic forms emphasizes the role ammonite paleoecology ( including larval ecology and dispersal abi l i ty) played together wi th the equable climate of the Jurassic (HALLAM, 1975) in shaping coeval ammonite faunas around the world. PALEOECOLOGY AND T A P H O N O M Y 55 C H A P T E R 5 PALEOECOLOGY AND T A P H O N O M Y In this chapter a paleoenvironmental reconstruction is at tempted by a paleoecological and taphonomical analysis of the ammonites, associated macrofauna, and trace fossils. The use of the Sinemurian ammonites of the Queen Char lot te Islands for environmental reconstruction is l imited by the following factors: - Ammon i t e death assemblages usually derive from a mixture of different habitats through the post-mortem drift of the shells. - M a n y aspects of functional morphology (e.g. whorl section, aperture, sutures, septa) are hindered by poor preservation. The shell size, volut ion, and ornament can be used to infer habitat . A n earlier model developed to explain the facies d is t r ibut ion of four basic morphotypes in the Lower Jurassic (TINTANT et a l , 1982) appears to be oversimplified. A p p l y i n g a recent synthesis on ammonite habitats (WESTERMANN, 1990) the studied fauna contains an array of nerit ic to pelagic and ba thya l forms. Bearing in m i n d that there is no ul t imately consistent relationship between the morphotypes and their presumed environment (KENNEDY and COBBAN, 1976), two interesting points are worth mentioning. Coroniceras ? spp. do not occur abundant ly in the assemblage of the "Coroniceras" Zone, whereas correlative faunas in the Taseko Lakes area and Nevada are dominated by this genus. Similar disparity is known from Europe where in nearshore environments of the Northwest European Province Coroniceras prevails but it is not par t icular ly abundant in the deeper water A l p i n e faunas. Coroniceras wi th its large, serpenticone, coarsely ornate shell is interpreted as nekto-benthonic organism restricted to shallow water nearshore environments. 5.1 AMMONITE PALEOECOLOGY PALEOECOLOGY AND T A P H O N O M Y 56 Sinemurian assemblages of the Mediterranean ammonitico rosso facies are dominated by phylloceratids and lytoceratids comprising up to two th i rd of the fauna (e.g. GECZY, 1972). These associations are interpreted as bathypelagic (ZlEGLER, 1967). A l though the Queen Char lo t te Islands fauna contains sporadic phylloceratids and lytoceratids, they never form a predominant part of the assemblage. 5.2 T H E PRESERVATION OF AMMONITES Ammoni t e s from the Sandilands and Ghost Creek Formations would not be the most wanted items of collectors and museum curators beacause of their notoriously poor preservation. The inferior state of preservation is a problem for the taxonomist but it also offers clues to understand the sedimentology and diagenetical history of the host rock. Despite the voluminous literature on ammonites, studies dealing wi th their preservational history are few. SEILACHER et al. (1976) presented a luc id and detailed treatment of Jurassic ammonite taphonomy of famous Ge rman lithofacies. The preservation of ammonites is controlled by their morphology and the sedimentological and diagenetic properties of the host rock. The recognition of the same morphotypes and analogous sedimentary environments permits the appl icat ion of some of the results of SEILACHER et al . (1976) to the Sinemurian fauna of the Queen Charlot te Islands. 5.2.1 CASE HISTORIES ( A ) Un i fo rm collapse Mos t of the s tudied ammonites are found as impressions in shale or siltstone. T h e ornament and the outline of shell is generally discernible, but the flattened test has min ima l relief. The phragmocone and the body chamber are indistinguishable. Th i s is the prevail ing preservation of the evolute, keeled, strongly r ibbed morphotype (e.g. arietitids, echioceratids). The low rate of sedimentation d id not allow for significant sediment infi l l ing of the shells. The amount of sediment entering the body chamber was not adequate to support it against collapse. The aragonitic shell was completely dissolved but the shiny black (e.g. Section D , PALEOECOLOGY AND T A P H O N O M Y 57 Level 17) or golden (e.g. Section H , Levels 17, 32) remains of the organic periostracal f i lm are conspicuous on some specimens. Fractures are often seen but never pervasive, suggesting that the corrugated ornament helped wi ths tand diagenetic collapse un t i l an advanced stage of shell dissolution. The collapse of the body chamber and phragmocone occurred nearly simultaneously when the shell was severely attenuated, losing its r igidity. Th i s type of preservation is analogous wi th that of DactyUoceras from the Posidonia Shale (SEILACHER et a l , 1976, fig. 5C) . (B) Two-phase collapse Morphotypes w i t h higher whorl section and more subtle r ibb ing behave differently under diagenetic pressure. Phyllocerat ids (e.g. PI . 1, F i g . 11) and oxynoticerat ids (e.g. PI. 13, F i g . 2) often show differential preservation as the body chamber collapses first when the shell is s t i l l r igid, resulting in marked fractures. The phragmocone, more resistant due to septal support , collapses later when advanced shell dissolution left only the flexible periostracal foil . A s a result, ornament is well preserved on the body chamber but masked on the phragmocone by soft deformation. The best examples of body chamber fractures are seen on large Oxynoticeras and Gleviceras specimens from Section H , Levels 16-17. Lack ing a keel or coarse r ibbing holding the shell together, angular fragments often protrude beyond the spiral outline. Th i s type is analogous wi th the "half-leaf" preservation documented by SEILACHER et al . (1976) on Harpoceras, Phylloceras, and Lytoceras from the Pos idonia Shale. (C) One-phase collapse wi th infilled body chamber Another type of differential preservation was observed on several specimens. The body chamber, although compressed, is not or only l i t t le fractured preserving significant relief, whereas the phragmocone is collapsed wi th the obli terat ion of ornament in the same manner as seen in type B (e.g. PI . 14, F i g . 8). A complete sediment infi l l ing of the body chamber is inferred. Because of the same sediment compaction rate inside and outside of the body chamber, and shell dissolution taking place simultaneously, no two-phase collapse occurred. Instead, reaching the flexible foil stage, the empty phragmocone collapsed entirely by soft PALEOECOLOGY AND T A P H O N O M Y 58 deformation while similar soft deformation compressed the body chamber to a l imi t dictated by its compact ing sediment infi l l ing. It is inferred that the bur ia l of these specimens took place during periods of higher sedimentation rate. Specimens wi th comparable taphonomical history are discussed and figured from the Pos idonia Shale by SEILACHER et al . (1976, fig. 18D). (D) B o d y chamber steinkerns Th i s type is rather rare in our material , recorded only in Section R and less obviously in Section P . A t the first locali ty almost undeformed internal moulds of body chambers can be recovered from the embedding rock (e.g. PI . 9, F i g . 1-2). Complete specimens, however, show flattened phragmocones. The evident difference to type C is that in this case (atypical for the Sandilands Format ion) rapid l i thif icat ion of the infi l l ing sediment preceded the dissolution of shell, therefore the internal mould suffered only minor compression and it is removable from the rock. (E) Shelly preservation A l t h o u g h rare, specimens wi th preserved original or recrystallized calcitic shell do occur in the s tudied mater ial (e.g. PI. 16, F i g . 5). W i t h o u t exception they are related to highly pyr i t ized beds or concretions, indicat ing that early cementation precluded shell dissolution when the shallow diagenetic environment environment immediately below the sediment-water interface was most reductive. (F) U m b i l i c a l concretions T y p i c a l nucleus concretions cored by ammonites or other fossil remains are unknown from the S inemur ian of the Queen Char lot te Islands. Umbi l i c a l concretions, a peculiar taphonomic phenomenon first described by SEILACHER et al . (1976, p. 342, fig. 16), are abundant in Section D , Level 27. The upper or lower side of the ammonites involved preserve unaltered relief and fine details of ornament on the umbi l icus . Conversely, the outer whorls are flattened (PI. 5, F i g . 7, PI. 6, F i g . 8). In all cases the umbil icus can be prepared by removing a light brown carbonate cemented concretion. It is assumed that early cementation of PALEOECOLOGY AND T A P H O N O M Y 59 the concretion preserved the original relief of ammonite shell from the effect of compactional deformation. In the majori ty of the observed cases umbi l i ca l concretions are attached to Vermiceras sp., characterized by wide whor l section and therefore rather deep umbil icus . It is obvious that the ammonite shells triggered or at least influenced the formation of these concretions, but more specific diagenetic studies are needed to understand the mechanism. 5.3 PALEOECOLOGY OF T H E ASSOCIATED M A C R O F A U N A 5.3.1 BIVALVES Bivalves constitute the second most common and diverse macrofossil group, far behind the ammonites in abundance. The following forms were identified: Pseudomytiloides sp. (PI. 17, F i g . 6) Pteriacea gen. et sp. indet. 1 (PI. 17, F i g . 3) Pteriacea gen. et sp. indet. 2 (PI. 17, F i g . 4, 7) Otapiria sp. A (PI. 17, F i g . 2, 11) Otapina sp. B Lupherella cf. boechiformis (HYATT) Oxytoma sp. (PI. 17, F i g . 9) Posidonotis semiplicata (HYATT) (PI. 14, F i g . 3; PI.15, F i g . 2) Camptonectes (Camptochlamys) sp. (PI. 17, F i g . 1, 5) Limea 7 sp. (PI. 17, F i g . 8) Plagiostoma ? sp. Mos t forms are th in shelled, commonly found in clusters or crowding bedding planes, presumably pseudopelagic in mode of life (Pseudomytiloides, Pter iacea gen. indet, Otapiria, Lupherella, Posidonotis). The PALEOECOLOGY AND TAPHONOMY 60 remaining taxa occur less frequently and are interpreted as epibenthonic. The inbenthos is not represented, suggesting persistent oxygen deficiency below the sediment-water interface. . 5.3.2 VERTEBRATES Nektonic vertebrate remains are not uncommon in the Sandilands Format ion . F i s h scales are widespread and several almost complete fish specimens were found (PI. 16, F i g . 2). The lack of disintegration provides evidence for the absence of benthonic life dur ing anoxic periods. The discovery of a skul l and part of the axial skeleton of Ichthyosaurus sp. from a loose slab found in Section D at Level 27, and another par t ia l skul l and rib fragments from Kennecott Poin t is reported by DENNISON et al . (1990). 5.3.3 STALKED CRINOID A unique specimen of Isocrinida gen. et sp. indet. was recovered from Section D above Level 26. The calix and part of the column, found on a weathered bedding plane, exceeds 110 c m in length . Morphologica l details of the calix necessary for a more exact identification (SIMMS, 1989) are eroded. Its closest affinities are among Pentacrvnites, Seirocrinus, and possibly Isocnnus. The extremely long and slender column and the intact preservation of this delicate fossil have paleoenvironmental implicat ions. The lack of disintegration of its complex and fragile structure embedded in dark, laminated shale suggests a complete lack of bioturbat ion and anoxic bo t tom conditions. The mode of life of similar stalked crinoids has long been the subject of controversy. The most perfectly preserved specimens are often found attached to driftwood suggesting pseudopelagic lifestyle (e.g. SEILACHER et al. , 1968). The extremely long column may have served to increase feeding efficiency as present day plankton dis t r ibut ion has a peak approximately 10 m below the surface (SIMMS, 1986). A n alternative interpretat ion insists on str ic t ly benthonic habitat for all pentacrinit ids (RASMUSSEN, 1977). Accord ing to this hypothesis, the function of the long stem was to raise the crown above the most oxygen-depleted bo t tom layer of water. PALEOECOLOGY AND T A P H O N O M Y 61 5.4 T R A C E FOSSILS The Sandilands Format ion in general is characterized by parallel laminat ion and lack of b io turbat ion. Nevertheless trace fossils were observed at various levels of different localities. The modern ichnology is pr imar i ly used for the determination of depositional environment using trace fossils (SEILACHER, 1978). Earl ier syntheses suggesting a direct relationship between paleobathymetry and trace fossil assemblages (SEILACHER, 1967) are now used wi th caution, recognizing a more complex effect of various ecological factors on ichnocoenoses (FREY et a l , 1990). However, the usefulness of commonly recurring trace fossil assemblages for facies interpretat ion is widely accepted (FREY and PEMBERTON, 1984). A detailed study of trace fossils of Sandilands Format ion is beyond the scope of this work, our treatment is l imited to record some occurrences offering paleoenvironmental implicat ions. Chondrites was found abundant ly at the base of Section G , not far below the base of the Canadensis Zone. BROMLEY and EKDALE (1984) noted that al though Chondrites occurs in a wide range of facies, it is the last persisting trace fossil i n sequences wi th decreasing O2 level. It is the exclusive trace fossil found in sediments formed under severely oxygen-depleted bo t tom condit ions. It is also recorded from the subordinate bioturbated interbeds of the predominant ly anoxic Pos idonia Shale in Germany (SAVRDA and BOTTJER, 1989). A more elaborate model establishing the low oxygen level tolerance of different trace fossils is developed by SAVRDA and BOTTJER (1986). Zoophycos, found in Section H in the Queen Charlot te Islands, can tolerate fairly oxygen deficient conditions. The same authors also observed positive correlation between burrow diameter and oxygenation level. A n unindentif ied three-armed trace fossil (Section F ) and several other burrows (Section D) reach 2-3 c m in diameter, suggesting relatively higher O2 content of bo t tom water. In Section H near Level 13 meandering, helminthoid-type trace fossils were found, indica t ing Nereites ichnofacies, commonly interpreted as ba thyal to abyssal (e.g. FREY and PEMBERTON, 1984). The Zoophycos. ichnofacies in the same model characterizes ba thyal or slope environment. PALEOECOLOGY AND TAPHONOMY 62 5.5 RESULTS In summary the following results emerge from the paleoecological and taphonomical analysis: - The scarcity of Coroniceras (characteristic to infralit toral) as well as Phylloceras and Lytoceras (predominant in bathypelagic environment) rule out the two paleobathymetric extremes of ammonite habitats represented in the studied assemblages. - Differences in ammonite preservational history indicate a variable sedimentary and diagenetic regime. Sedimentation rate was generally slow but increased at times. The diagenetic history of parts of the sequence also differ in t iming of cementation, presumably related to f luctuating redox conditions in the upper sediment layers. - The lack of infaunal bivalves, scarcity of epifaunal forms and preponderance of th in shelled, pseudopelagic taxa is explained by prevail ing anaerobic-dysaerobic bo t tom conditions. - The intact preservation of nektonic vertebrates and a stalked cr inoid suggests the lack of scavangers and bioturbat ion precluded again by oxygen deficient conditions. T h e inferred pseudoplanktonic or alternately benthonic mode of life of the isocrinid cr inoid is in accordance of this model, as in the latter case the long column may have served to raise the crown above the lowest, most O2 depleted water layers. - Unbio turba ted and parallel laminated beds indicate bo t tom conditions entirely prohibit ive of benthonic life. Beds wi th Chondrites mark the passage of the O2 level threshold, al lowing benthonic life restricted to taxa most tolerant to oxygen deficiency. Periodic rise of O2 level is further documented by the appearance of Zoophycos and burrows of larger diameter. S Y S T E M A T I C P A L E O N T O L O G Y INTRODUCTION 63 C H A P T E R 6 SYSTEMATIC PALEONTOLOGY 6.1 INTRODUCTION Ammonoids collected dur ing this s tudy and supplemented wi th some of the existing G S C collections are dealt wi th in this chapter. For the ammonoids the most detailed and sound identification possible has been attempted to form an independent taxonomic study as well as to provide raw data for biostratigraphic and paleobiogeographic analysis. The description of one bivalve of stratigraphic importance is included, the other identified forms are listed in Chapter 5. The classification of Phyl locera t ida and Lytocera t ida is adopted from A R K E L L et al . (1957) wi th modifications by W l E D M A N N (1970). The systematics of A m m o n i t i n a largely follows the outline given by D O N O V A N et al . (1981) which was intended to form a basis of the revised but as yet unpublished edit ion of the Treatise on Invertebrate Paleontology. Special reference is made to other authors wherever deviation from this classification is needed in the light of more recent work (e. g. B L O O S , 1988 for the schlotheimiids). Due to its poor preservation (e. g. sutures are seldom preserved) the studied mater ial is not suitable for resolving classification problems. However, in some cases comments are made on such questions. The common mode of preservation of ammonites in the Sandilands Format ion is as flattened internal moulds resulting in significant information loss, especially for ventral features and whor l section. The extensive use of open nomenclature is therefore inevitable. T h e recommendations of B E N G T S O N (1988) are followed regarding the meaning and syntax of signs of open nomenclature. One exception is the cf. and ? where the usage of M A T T H E W S (1973) is preferred, i . e. cf. means uncertainty mainly due to incomplete preservation whereas ? is used to express uncertainty because of provisional identification. Synonymy lists are composed according to the suggestions of M A T T H E W S (1973) wi th the type material indicated by an asterisk. Specimens seen are marked wi th "v" . If a recent revision of a taxon is available and accepted, reference is made to it as "wi th synonymy" . S Y S T E M A T I C P A L E O N T O L O G Y INTRODUCTION 64 The measurements and the descriptive morphological terms conform wi th those used by SMITH (1986). S tandard abbreviations are also adopted from there (F ig . 7-1). Th i s enables computerized data management on the studied mater ial using the A M M O N database. The list of abbreviations used is as follows: D M A X - M a x i m u m measurable diameter D - Diameter at which other measurements were taken (if different from D M A X ) U D - U m b i l i c a l diameter U - UD/D*100 ; Ra t io of umbi l ica l diameter and diameter W H - W h o r l height P R H W - Number of pr imary ribs per half whorl S R H W - Number of secondary ribs per half whorl T H W - Number of tubercles per half whorl U R H W - Number of umbi l i ca l rib ends per half whorl V R H W - Number of ventral rib ends per half whorl V U R R - Ra t io of ventral and umbi l ica l rib ends , The last three parameters are introduced for the description of schlotheimiid r ibbing following the practice of BLOOS (1979, 1988). They are suitable to characterize a r ibb ing pat tern wi th irregular bifurcation and secondary rib intercalat ion. Due to the two-dimensional preservation and the prevail ing morphology of Ar ie t i t idae ( i . e. simple r ibbing on evolute shell), r ib frequency curves are effective tools for identification. Since rib density often changes throughout ontogeny, it is important to obtain rib counts on inner whorls as well . A s the diameter of inner whorls cannot be accurately measured due to whorl overlap, umbi l ica l diameter is used to plot against the number of pr imary ribs per half whor l . Th i s is a departure from the method used by other workers, e. g. GUERIN-FRANIATTE (1966) and GETTY (1973). S Y S T E M A T I C P A L E O N T O L O G Y PHYLLOCERATINA 65 6.2. SYSTEMATIC DESCRIPTIONS O R D E R A M M O N O I D E A ZlTTEL, 1884 S U B O R D E R P H Y L L O C E R A T I N A ARKELL, 1950 S U P E R F A M I L Y P H Y L L O C E R A T A C E A E ZlTTEL, 1884 F A M I L Y P H Y L L O C E R A T I D A E ZlTTEL, 1884 G E N U S Phylloceras SUESS, 1865 T Y P E S P E C I E S - Ammonites heterophyllus SOWERBY, 1820, by original designation. D E S C R I P T I O N - Involute forms wi th compressed whor l section and small umbil icus . F ine ornamentation on shell surface what is usually not preserved on internal m o u l d . A G E A N D D I S T R I B U T I O N - A long ranging genus (Sinemurian to Valanginian) wi th a world-wide dis tr ibut ion. Pa r t i cu la r ly abundant in some Te thyan faunas, especially in the circum-Mediterranean region. Phylloceras sp. PI. 1, F i g . 4 M A T E R I A L - One well preserved specimen in siltstone. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H W W C-156980/21 14.2 2.0 14.3 6.9 4.5 S Y S T E M A T I C P A L E O N T O L O G Y PHYLLOCERA TINA 66 D E S C R I P T I O N - Involute shell of small size. W h o r l of ell ipsoid section, umbi l ica l wal l low wi th rounded shoulder. F lanks convex, venter rounded. Ornament consisting of very fine striae. D I S C U S S I O N - Th i s specimen does not allow specific identification notwiths tanding its relatively good preservation. O C C U R R E N C E - Kennecot t Poin t , section D , level 27; from the top of the Canadensis Zone. F A M I L Y D I S C O P H Y L L I T I D A E SPATH, 1927 (sensu WlEDMANN, 1970) G E N U S Juraphyllites MULLER, 1939 T Y P E S P E C I E S - Phylloceras diopsis, GEMMELLARO, 1884, by original designation. D E S C R I P T I O N - Midvo lu t e forms wi th angular umbi l ica l shoulder. Inner whorls usually smooth or wi th widely spaced constrictions. Coarse r ibbing on venter and upper flanks characteristically develops on body chamber only, which often shows egression. R E M A R K S - There have been nearly twenty nominal species assigned to luraphyliites. Taxonomica l problems arise from the,lack of designated types in many cases and the different wid th of the species concept employed by different authors. A modern comprehensive revision would be necessary to solve the current problems, some of which are mentioned in the discussions below. A G E A N D D I S T R I B U T I O N - The genus occurs in Sinemurian and Pl iensbachian of the Te thyan realm. In Europe, where it is best documented, it is abundant in the Medi terranean region but becomes less frequent nor thward and vi r tua l ly absent in the Northwest European province. Occurrences in other parts of the world S Y S T E M A T I C P A L E O N T O L O G Y PHYLLOCERATINA 67 include records from N o r t h A m e r i c a (Nevada: SMITH, 1981; Mexico : ERBEN, 1956), South Amer i ca (Argent ina : HlLLEBRANDT, 1987), Soviet Fa r East (SEY and KALACHEVA, 1988), C h i n a (Guangdong region, WANG and SMITH, 1986) and the Himalayas (DlENER, 1908). Juraphyllites cf. limatus (ROSENBERG, 1909) PI . 1, F i g . 8 cf.* 1909 Rhacophyllites limatus spec. nov. - ROSENBERG, p.35, p i . 11, fig. 10-11 cf. 1923 Kochites limatus ROS. - FUCINI, p. 105, p i . 7, fig. 11 cf. 1942 Rhacophyllites limatus ROSENBERG - KOVACS, p. 115, p i . 5, fig. 6 cf. 1977 Juraphyllites limatus limatus (ROSENBERG,1909) - WlEDENMAYER, p. 37, p i . 3, fig. 4, p i . 8, fig. 8, 12, text-fig. 8j-l T Y P E - Lectotype: PI . 11, fig. 10 of ROSENBERG (1909), deposited in the Paleontological Institute, Univers i ty of V i e n n a (WlEDENMAYER, 1977). M A T E R I A L - One flattened fragmentary in ternal mould in shale, preserving very li t t le relief. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H 7 2 4 Q F / 3 30.7 7.7 25.1 14.3 D E S C R I P T I O N - M e d i u m sized, midvolute shell. Expans ion rate decreasing on last whorl . Smooth, no ornamentation is discernible. D I S C U S S I O N - The poor preservation necessitates the use of open nomenclature. The volut ion and the lack of r ibbing are in good agreement wi th the synonymized material . W i t h o u t obvious egression or apertural S Y S T E M A T I C P A L E O N T O L O G Y PHYLLOCERA TINA 68 modification one cannot conclude on the ontogenetic stage of the indiv idual , thus a larger species of Juraphyllites wi th smooth inner whorls is not ruled out wi th certainty. The morphologically closest species is I. stella (SOWERBY, 1833) which is readily dist inguished from J. limatus by its prominent constrictions. The smooth forms of Phylloceras s. 1. al l have a considerably smaller umbil icus . O C C U R R E N C E - Tasu Sound area, Section P , presumably from the A r n o u l d i Zone (collected from float). D I S T R I B U T I O N - I. limatus has been recorded from the Upper Sinemurian (?) of Mon te d i Cetona, Nor thern Appenines , Italy (FUCINI, 1923); Hettangian (?) to Pl iensbachian of the B a k o n y M t s , Hungary (KOVACS, 1942); and the Lower Pl iensbachian of the Hagen M t s , Nor thern A l p s , A u s t r i a (ROSENBERG, 1909). Juraphyllites cf. transylvanicus (HAUER, 1866) PI. 1, F i g . 1-2 cf. 1866 Ammonites transylvanicus n. sp. - HAUER, p.192 cf. pars 1878 Phylloceras transylvanicum Hauer - HERBICH, p. 114, pi 20J, fig. 1 (non pi. 20H, fig. 2) cf. 1901 Rhacophyllites transylvanicus HAUER - FUCINI, p.52, pi. 8, fig. 1-7 cf. 1908 Rhacophyllites transylvanicus Hau. sp. - VADASZ, p.323 cf. 1981 Juraphyllites cf. dorsocurvata (Fucini, 1901) - SMITH, p. 129, pi. 1, fig. 2 M A T E R I A L - 18 specimens, mostly poorly preserved, fragmentary impressions in shale and siltstone. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W 724F/1 « 5 8 7.3 ss l3 31.8 %30 705E/1 %56 - - - 28 7 2 4 Q F / 1 %49 S5l2 as21 %28 705E/10 47.7 6.5 13.6 20.7 27 S Y S T E M A T I C P A L E O N T O L O G Y PHYLLOCERATINA 69 D E S C R I P T I O N - Midvo lu t e form at ta ining med ium to large size for genus. A d u l t s show egression on body-chamber. Exclus ively flattened preservation does not allow observation on whorl shape and venter. F ine r ibbing develops on last whor l becoming sl ightly coarser toward aperture. Ribs gently prorsiradiate originating on lower part of middle flank, in some specimen gently bent forward ventrally. N o constrictions discernible. D I S C U S S I O N - Juraphyllites transylvanicus is a poorly established and perhaps for this reason not frequently cited species wi th a brief or iginal description lacking figures and without a designated type. Similar but better understood species include J. diopsis and J. libertus. The first differs from J. transylvanicus mainly by its r ibbing being coarser on body chamber, more projected ventral ly and originating higher on middle flank. The latter is readily dist inguished by the presence of widely spaced, faint constrictions. Our specimens are more involute than the ones figured by HERBICH (1878) and FUCINI (1901). A l so the r ibbing appears to develop at an earlier stage occupying the entire last whor l instead of the body chamber only. / . dorsocurvata (FUCINI, 1901), originally described as a subspecies of J. transylvanicus, was raised to species status by SMITH (1981) based on well preserved material from Nevada. It is smaller than the Queen Charlot te form judged from a mature specimen wi th ros t rum. J. nardii has finer and sigmoidal costation. O C C U R R E N C E - Kennecot t Po in t , Section D , Level 21, K u n g a Island, Section S and T ; from the "Coroniceras" Zone; Tasu Sound area, Section P , Level 6; from the A r n o u l d i Zone. D I S T R I B U T I O N - J. transylvanicus has been recorded from the Te thyan realm in Europe: Transy lvan ia (HAUER, 1866, HERBICH, 1878, VADASZ,1908), and Monte d i Cetona, Nor thern Appenines, Italy (FUCINI, 1901). The age of the European occurrences is poorly constrained but probably Sinemurian. S Y S T E M A T I C P A L E O N T O L O G Y PHYLLOCERA TINA 70 Juraphyllites aff. nardii (MENEGHINI, 1853) PI . 1, F i g . 3, 5-7 aff. 1856 Ammonites Mimatensis D ' O R B . - H A U E R , p. 56, p i . 17, fig. 1-3 aff. 1879 Ammonites nardii M E N E G H . - R E Y N E S , p i . 21, fig. 12-16 aff. 1901 Rhacophyllites nardii M G H . - FUCINI, p. 48, p i . 7, fig. 1-7 aff. 1978 Juraphyllites gr. nardii - V E N T U R I , p. 101, p i . 1, fig. 5 M A T E R I A L - 19 specimens preserved in shale and siltstone in various degrees of compression (from slightly compressed internal mould to flattened impressions). M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W Y L 4 7 / 8 [M] 62.4 7.0 11.2 30.0 34 Y L 4 7 / 7 [M] w60 %8 ss l3 « 2 5 24 Y L 4 7 / 1 0 [M] 53.6 6.2 11.6 23.6 35 Y L 4 7 / 7 [M] 47 7.3 15.5 22.8 21 1 A 5 / 1 [M] ss41 6.2 %15 %19 « 3 0 7 0 7 M / 1 [m] 36.8 7.3 19.8 16.0 18 P L S 2 1 / 2 [m] 34.8 7.3 20.9 16.0 -P L S 2 1 / 1 [ m ] 28.6 6.8. 23.8 12.7 « 1 6 D E S C R I P T I O N - Macroconch: Involute shell of m e d i u m to large size for genus reaching a m a x i m u m diameter of 65 m m . Moderate ly expanding whorls, body chamber showing egression. Umbi l i cus small , umbi l i ca l shoulder rounded. The whorl section and the height of umbi l ica l wal l cannot be judged on flattened specimens. Ornament variocostate, densely r ibbed throughout at least the last whor l . Prorsiradiate, sl ightly sigmoidal ribs of rounded triangular profile originat ing on lower flank, gently projected forward on upper flank crossing the venter uninterrupted. W i d e l y spaced single or paired constrictions flanking a swollen rib occur irregularly on phragmocone. N o apertural modificat ion observed. Sutures not preserved. Mic roconch : Approx imate ly half of size of a macroconch, shell less involute , diameter less than 4 cm. Umbi l i cus wider, high and steep umbi l ica l wall on less crushed specimens. M o r e coarsely r ibbed, whereas SYSTEMATIC PALEONTOLOGY PHYLLOCERA TINA 71 1 mm Figure 6-1 Septal suture of Juraphyllites aff. nardii. Specimen PLS21/2, drawn at WH=15mm, x6.8. strongly prorsiradiate constrictions more prominent than on macroconch. Sutures simple with phylloid saddle endings (Fig. 6-1). One specimen (PLS21/2) shows sutural approximation at end of phragmocone. DISCUSSION - This form cannot be confidently assigned to any established species. It shows closest resemblance to Juraphyllites nardii (MENEGHINI, 1853) as described and figured by FUCINI (1901, p.48, pi. 7, fig. 1-7), REYNES (1879, pi. 21, fig. 12-16) and VENTURI (1978, J. gr. nardii, p. 101.pl. 1, fig. 5). However, fundamental differences exist as ribbing on J. nardii develops only on the body chamber, usually on the last half whorl whereas our specimens are ribbed throughout the last whorl. Presumably ribbing develops in an earlier growth stage, bad preservation, however, commonly obscures the details. This character points toward affinity (probable ancestorship) of Tragophylloceras. Also J. nardii has less involute (commonly midvolute) coiling. Close comparison can be based on similar variocostate ornament, sigmoidal, prorsiradiate ribbing, and irregular constrictions. Our material derived from beds of the same stratigraphic position representing almost exclusively monospecific collections from four different localities. This is a strong argument for interpreting the morphologically slightly different forms as sexually dimorph macroconch/microconch pairs. Maturity in Juraphyllites can be judged from egression on body chamber or from sutural approximation near the end of the phragmocone. Mature specimens fall into two broad groups: macrochonchs attaining large diameter and characterized by denser ribbing and smaller umbilicus; and smaller, less involute, more coarsely ribbed S Y S T E M A T I C P A L E O N T O L O G Y PHYLLOCERATINA 72 microchonchs. The [M]/[m] frequency ratio varies significantly f rom one locali ty to another: samples at Y a k o u n River are largely [M] dominated (4:1) and the opposite was found in K u n g a Island (c. 1:3). The relatively small number of individuals does not warrant a stat ist ical analysis. The above dispari ty is not unprecedented, similar cases have been reported (for examples see CALLOMON, 1981). Beside the b imodal d is t r ibut ion of size and other morphologic variables a phylogenetic criterion should also be met before concluding upon sexual d imorphism: this phenomenon appears to occur in lineages rather than in isolated taxa (CALLOMON, 1981). N o proven examples of d imorphism of Juraphyllites have been demonstrated yet, but the possibi l i ty was raised by SMITH (1981) for J. dorsocurvata (FUCINI, 1901) and / . lunensis (DE STEFANI, 1886). HOWARTH and DONOVAN (1964) demonstrated sexual d imorphism in Ear ly Pl iensbachian Tragophylloceras which is thought to have been evolved from Juraphyllites. O C C U R R E N C E - Y a k o u n River , Section H , Levels 49 and 52; central G r a h a m Island, Section L , Level 3; Maude Island, Section M , Level 6; K u n g a Island, section T , Levels 56 and 60; from the upper part of Recogni tum Zone except for H / 5 2 , which is from the base of Imlayi Zone. Juraphyllites sp. P L 1, Fig. 9 M A T E R I A L - One specimen of mediocre preservation in concretion. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H 608B/8 35.5 7.3 20.6 17.6 S Y S T E M A T I C P A L E O N T O L O G Y PHYLLOCERA TINA 73 D E S C R I P T I O N - Moderate ly involute shell wi th sharp, umbi l ica l edges. Last whor l showing incipient egression. Smooth up to the last half whor l . The last quarter of a whorl bears seven rather coarse ribs of various length, or iginat ing on m i d to upper flank. D I S C U S S I O N - T h e assignment of this specimen to Juraphyllites is supported by the variocostate ornament on last whorl and the incipient egression. Specific identi ty cannot be established due to the incomplete preservation of the cri t ical part of the last whor l where the r ibbing develops. J. cf. limatus differs from this form in retaining a smooth shell at comparable diameter. O C C U R R E N C E - Kennecot t Po in t , Section D , Level 27; from the top of Canadensis Zone. O R D E R L Y T O C E R A T I D A HYATT, 1889 S U B O R D E R L Y T O C E R A T I N A HYATT, 1889 S U P E R F A M I L Y L Y T O C E R A T A C E A E NEUMAYR, 1875 F A M I L Y L Y T O C E R A T I D A E NEUMAYR, 1875 G E N U S Lytoceras SUESS, 1865 T Y P E S P E C I E S - Ammonites fimbnatus J . SOWERBY, 1817 S Y N O N Y M Y - See WlEDMANN, 1970, p. 992. D E S C R I P T I O N - Ext remely evolute shell w i th whorls of rounded or quadrate cross section. Ornament consisting of fine, dense riblets or growth lines and often widely spaced flares on shell wi th corresponding constrictions on internal mould . S Y S T E M A T I C P A L E O N T O L O G Y LYTOCERATINA 74 A G E A N D D I S T R I B U T I O N - Lytoceras is a long-ranging genus occuring world-wide from the Sinemurian to the Upper Cretaceous. Lytoceras sp. PI . 1, F i g . 11 M A T E R I A L - One specimen preserved as flattened impression in shale. M E A S U R E M E N T S - Specimen N o . 609H/9 D M A X = 1 0 0 U D = 3 6 U=36 W H = 3 7 D E S C R I P T I O N - Advo lu te form wi th rapidly enlarging whorls hence umbil icus representing only approximately one th i rd of diameter. No ornament visible on phragmocone due to crushed preservation. Body chamber ^ / g whor l long, densely covered by fine riblets some of which stronger than others at irregular intervals. D I S C U S S I O N - The poor preservation renders a full assessment of the specimen impossible. The type species Lytoceras fimbnatum is similar in many aspects but can be dist inguished by its prorsiradiate ornament. L. secernendum STEFANI, 1886 resembles to the studied specimen in volut ion and ornament of body chamber. Its diagnostic constrictions" on the inner whorls cannot be seen on our ind iv idua l . O C C U R R E N C E - Kennecott Po in t , Section D , Level 17; from the Canadensis Zone. Lytoceras spp. P L 1, F i g . 10,12 M A T E R I A L - 10 specimens mostly preserved as flattened in ternal moulds in shale. SYSTEMATIC PALEONTOLOGY LYTOCERATINA 75 Figure 6-2 Septal suture of Lytoceras sp. Specimen 611M/2, drawn at WH=17 mm, x6.8. DISCUSSION - Several forms are being grouped together Lytoceras spp. They all share lytoceratid affinities expressed in very evolute shell form, more or less rapidly enlarging whorls, and general lack of ornament. One specimen (611M/2) shows typical lytoceratid sutures (Fig. 6-2). Given the two-dimensional preservation, these relatively featureless forms cannot be identified with greater precision, nonetheless they provide valuable information regarding the composition of the Sinemurian ammonite fauna of the Queen Charlotte Islands. OCCURRENCE - The studied specimens originated from various levels in sections A, D, and F at Kennecott Point, from the Canadensis and "Coroniceras" zones. GENUS Adnethiceras WlEDMANN, 1970 T Y P E SPECIES - Ammonites adnethicus HAUER, 1854, by original designation. S Y S T E M A T I C P A L E O N T O L O G Y LYTOCERATINA 76 D E S C R I P T I O N - Advo lu t e lytoceratids of moderate expansion rate. W h o r l section subcircular. Massive, coarse r ibbing emerging gradually after a smooth stage of various durat ion. Ribs crossing venter, swollen at ventro-lateral shoulder. R E M A R K S - A detailed treatment of the genus w i t h a list of species included is given by WlBDMANN (1970). A G E A N D D I S T R I B U T I O N - Adnethtceras is known from the Sinemurian of the Mediterranean Province of Europe (Spain, Italy, A u s t r i a , Rumania ) . Th i s is the first record of genus from N o r t h Amer i ca . Adnethtceras cf. adnethicum (HAUER, 1854) PI . 2, F i g . 4 cf. 1970 Adnethtceras cf. adnethicum (HAUER) - WlEDMANN, p. 998, p i . 8, fig. 1; text-fig. 25, 27b, 30K-L (with synonymy) T Y P E - Holotype: Ammonites Adnethicus HAUER, 1854, p i . 1, fig. 2-3, refigured by WlEDMANN, 1970, p i . 8, fig. 1; text-fig. 30K; deposited in the Geologische Bundesanstal t , Vienna,Specimen No . 576. M A T E R I A L - One poorly preserved compressed external mould . M E A S U R E M E N T S - Specimen No. 706O/2 D M A X = 5 7 . 4 U D = 2 7 . 8 U=48.4 W H = 1 6 . 0 P R H W = 1 4 (Note: Linear measurements are exaggerated due to preservational distortion.) D E S C R I P T I O N - High ly evolute (advolute?) shell, whorls enlarging moderately rapidly. Flanks convex, umbi l ica l wal l and shoulder not developed, or iginal whor l section likely to be inflated.Inner whorls somewhat obliterated due to poor preservation but appear to be smooth. Dense, coarse r ibbing develops from an S Y S T E M A T I C P A L E O N T O L O G Y LYTOCERATINA 77 umbi l i ca l diameter of approximately 7 m m . Ribs straight, rectiradiate, of high but rounded profile. A l t h o u g h venter not seen, ribs l ikely to cross over as being projected beyond contour of shell on bedding plane. Ribs strengthening ventral ly. D I S C U S S I O N - Despite its poor preservation our specimen is in general agreement wi th the lateral views of the type material . A. haueri WlEDMANN, 1970 differs by its denser r ibb ing and more slender whor l section. O C C U R R E N C E - K u n g a Island, Section T , Level 32; from the top of A r n o u l d i Zone. D I S T R I B U T I O N - A. adnethicum is known from the A d n e t h region of Nor thern A l p s , A u s t r i a , the Cen t r a l Appenines, Italy (WlEDMANN, 1970), and the Betic Cordi l lera , Spam (BRAGA et a l , 1984, 1985). G E N U S Tragolytoceras SPATH, 1924 T Y P E S P E C I E S - Ammonites altecmctus HAUER, 1866 by original designation. D E S C R I P T I O N - V e r y evolute forms of small to med ium size. Inner whorls smooth, blunt r ibb ing developing gradually giving Capricorn appearance to outer whorls. R E M A R K S - The genus is not well understood as the type mater ial is lost and information on suture lines is lacking. (WlEDMANN, 1970). A G E A N D D I S T R I B U T I O N - Tragolytoceras is known from the Sinemurian of the Medi terranean Province in Europe. Th i s is the first record of the genus from N o r t h A m e r i c a . S Y S T E M A T I C P A L E O N T O L O G Y LYTOCERATINA 78 Tragolytoceras ? sp. PI . 2, F i g . 2 M A T E R I A L - One specimen preserved as flattened internal mould in shale. M E A S U R E M E N T S - Specimen No . Y L 1 0 / 1 D M A X = 2 9 . 8 UD=10 .70 U=35.9 W H = 9 . 4 D E S C R I P T I O N - V e r y evolute shell of a smal l diameter (3 cm). Whor l s enlarging moderately rapidly, hence umbil icus representing approximately one th i rd of diameter. Preserved relief suggesting flattened or sl ightly convex flanks. Inner whorls smooth up to an umbi l i ca l diameter of 7 m m from which point coarse, blunt r ibbing develops gradually. Ribs originat ing approximately at one th i rd of flank, gently prorsiradiate and incl ined forward, strongest at ventro-lateral shoulder. D I S C U S S I O N - The allocation of our form to Tragolytoceras cannot be satisfactorily proven. It most closely resembles to some of the figured specimens of the type species T. altecmctum (especially BONARELLI, 1900, pi . 9, fig. 1). The Queen Char lot te specimen displays similar style of ornament differing mainly in having more forwardly incl ined ribs. However, affinities to Arnioceras, suggested by the smooth nucleus cannot be ruled out. R i b b i n g confined to the middle and upper flank is not typica l for that genus. The only comparable form is described from the basal Upper S inemur ian of Tunes ia as Arnioceras fieldmgoceroid.es DOMMERGUES et al . , 1986 (p. 1115, p i . 1, fig. 7-8). V e n t r a l features, not available on our specimen are needed for unequivocal identification. O C C U R R E N C E - Y a k o u n River , Section H , Level 11; from the top of the A r n o u l d i Zone. S Y S T E M A T I C P A L E O N T O L O G Y LYTOCERATINA 79 F A M I L Y D E R O L Y T O C E R A T I D A E S P A T H , 1927 G E N U S Audaxlytoceras FUCINI, 1923 T Y P E - Lytoceras audax MENEGHINI , 1881, subsequent designation by A R K E L L , 1957. D E S C R I P T I O N - Smal l , evolute lytoceratids wi th low expansion rate and compressed whor l section. Smooth except for widely spaced constrictions on internal mould corresponding to rudimentary ribs or flares on shell. R E M A R K S - A thorough revision and clarification of systematic and nomenclatural status of the genus is given by FANTINI SESTINI, 1973. The genus was placed into Analytocerat idae by S P A T H (1927). A R K E L L (1957) assigned it to Nannolytoceratidae while most recently FANTINI SESTINI (1973) presented an argument for classifying it as a genus of Derolytoceratidae, this view is accepted herein. W l E D M A N N (1970) pointed out the s t r ik ing morphological s imilar i ty of Audaxlytoceras to Trachyphyllites, a monospecific genus only known from the Upper Triassic of T imor . He used it to support far-reaching evolutionary consequences concerning the connecting links between Triassic and Jurassic ammonoids, a view challenged by T O Z E R (1971) based on the demonstrably controversisal age assignment of the T i m o r specimen. If the correct age is in fact Ear ly Jurassic, Trachyphyllites may be best regarded as a junior subjective synonym of Audaxlytoceras. A G E A N D D I S T R I B U T I O N - Audaxlytoceras is restricted to the Sinemurian to Toarc ian of the Mediterranean Province in Europe (FANTINI SESTINI, 1973). Th i s is the first record of the genus from Nor th Amer ica . Audaxlytoceras aff. audax (MENEGHINI , 1881) PI. 2, F i g . 6 cf. 1927 Lytoceras sp., aff. Lytoceras audax Menegh. - S C H R O D E R , p. 154, p i . 9, fig. 1 1927 Monophyllites (Trachyphyllites) costatus n. sp. - A R T H A B E R , p. 141, p i . 17, fig. 3 S Y S T E M A T I C P A L E O N T O L O G Y LYTOCERATINA 80 ? 1970 Trachyphyllites costatus ARTHABER - WlEDMANN, p. 987, p i . 5, fig. 6, text-fig. 8a-b (Holotype refigured) (with synonymy) aff. 1973 Audaxlytoceras audax (MENEGHINI, 1881) - FANTINI SESTINI, p. 490, p i . 49, fig. 1-3 (wi th synonymy) M A T E R I A L - One flattened specimen preserved in shale. M E A S U R E M E N T S - Specimen No . 7 2 4 A / 1 D M A X = 2 7 . 1 UD=11 .4 U=42.1 W H = 8 . 5 P R H W = 4 D E S C R I P T I O N - Advo lu te shell of smal l size. W h o r l expansion rate moderately high. Nucleus smooth, from an umbi l i ca l diameter of 2 m m widely spaced, adorally convex rudimentary ribs (flares) develop. Last whorl bearing 8 ribs, some of t hem flanked by a shallow constrict ion. 3 ribs on last ^ /g whorl - two of t hem very closely spaced - possibly indica t ing matur i ty . Ven t r a l view and sutures not available. D I S C U S S I O N - A m o n g the species assigned to Audaxlytoceras by FANTINI SESTINI (1973), the type species appears to be the most closely related to our form. The specimens figured by FANTINI SESTINI at tain sl ightly higher size and show higher whor l expansion rate. SCHRODER (1927) i l lustrated a specimen resembling the Queen Char lot te ind iv idua l except for its fine, short vetro-lateral riblets. Based purely on the lateral views, very close comparison can be made wi th the single specimen of Trachyphyllites costatus ARTHABER. Should it have originated from Sinemurian , not Nor ian strata as the probabi l i ty was proposed by TOZER (1971), the two are l ikely to be very closely related. N o conclusion can be drawn without more and better preserved material . O C C U R R E N C E - Tasu Sound area, Section P , Level 1; from the upper part of the A r n o u l d i Zone. D I S T R I B U T I O N - A. audax is known from the Pl iensbachian of Italy and Aus t r i a . SCHRODER'S (1927) A. aff. audax originated from the Sinemurian of the Bavar ian A l p s , Germany. Trachyphyllites costatus was found in the Upper Triassic or possibly Sinemurian of T i m o r . S Y S T E M A T I C P A L E O N T O L O G Y LYTOCERATINA 81 F A M I L Y P L E U R O A C A N T H I T I D A E HYATT, 1900 S U B F A M I L Y E C T O C E N T R I T I N A E SPATH, 1927 G E N U S Ectocentrites CANAVARI, 1888 T Y P E S P E C I E S - Ammonites petersi HAUER, 1856, subsequent designation by BONARELLI, 1900. S Y N O N Y M Y - Cosmolytoceras SPATH, 1924 D E S C R I P T I O N - Evolute forms wi th moderate whor l expansion rate. W h o r l section quadrate to rounded, venter broad, smooth and flattened. Ornament consisting of dense, straight or sl ightly flexuous r ibbing of fine to med ium thickness. A G E A N D D I S T R I B U T I O N - Ectocentrites is characteristically Te thyan i n d is t r ibut ion . It is known from the Upper Hettangian(?)-Sinemurian of the Medi terranean Province, Himalayas , T i m o r and Chi le . It has not been previously recorded from Nor th Amer ica . Ectocentrites ? sp. PI . 2, F i g . 1, 5 M A T E R I A L - 3 flattened internal moulds of body chamber fragments. D E S C R I P T I O N - Fragments of specimens of large size, whor l height reaching 60 m m . Curva ture suggesting moderately wide umbil icus. Densely r ibbed, p r imary ribs sl ightly flexuous, probably crossing venter. 2 to 4 fine secondary ribs between primaries, strongest on upper flank and near ventro-lateral shoulder. S Y S T E M A T I C P A L E O N T O L O G Y LYTOCERATINA 82 D I S C U S S I O N - The fragmentary and poorly preserved material does not allow more precise identification. The generic assignment is based on the style of ornament and volut ion. Closely related specimens are i l lustrated by WAHNER from the M a r m o r e u m Zone of the A l p s as Ectocentrites petersi italicus CANAVARI, 1882 (1898, p. 279, especially p i . 20, fig. 1-3; p i . 2, fig. 1-2). Another remarkably similar ind iv idua l from the B u c k l a n d i Zone of T i m o r is i l lustrated by KRUMBECK as Ectocentrites sp. nov. aff. itahco (1923, p. 110, p i . 177, fig. 7).Reasonable comparison can be drawn wi th E. altiformis BONARELLI, 1900 (e. g. BONARELLI, 1900, p i . 9, fig. 4; FUCINI, 1901, p i . 14, fig. 9) al though this species lacks secondary r ibbing. O C C U R R E N C E - Kennecot t Poin t , Section D , Level 27; from the top of the Canadensis Zone. F A M I L Y A N A L Y T O C E R A T I D A E SPATH, 1927 G E N U S Eolytoceras FREBOLD, 1967 T Y P E S P E C I E S - Eolytoceras tasekoi FREBOLD, 1967, by original designation. D E S C R I P T I O N - Evolu te forms of m e d i u m size, whor l section ellipsoid. Ornament consisting of very fine ribs arid widely spaced flares on shell w i th corresponding constrictions on internal mould . Suture line wi th trifid lateral lobes and phy l lo id saddle endings. R E M A R K S - WlEDMANN (1970) assigned the genus to the family Analytocerat idae on the basis of sutural characteristics already emphasized by FREBOLD (1967). A G E A N D D I S T R I B U T I O N - Eolytoceras appears to be confined to the uppermost Het tangian-Lower Sinemurian of Western N o r t h A m e r i c a (Br i t i sh Co lumbia : FREBOLD, 1967; Nevada: GUEX and TAYLOR, 1976, TAYLOR, 1990), i . e. the Athabascan Province sensu TAYLOR et a l , 1984. S Y S T E M A T I C P A L E O N T O L O G Y LYTOCERATINA 83 Eolytoceras tasekoi FREBOLD, 1967 PI. 3, Fig. 1, 4 * v 1967 Eolytoceras tasekoi n . sp. - FREBOLD, p. 14, p i . 8, fig. 1-2, text-fig. 2 1970 Eolytoceras tasekoi FREBOLD - WlEDMANN, p. 1007, p i . 7, fig. 4, text-fig. 9c, 30D, 31 (Holotype refigured) T Y P E - Holotype: Eolytoceras tasekoi FREBOLD, 1967, p i . 8, fig. 2, G S C T y p e No . 20059. M A T E R I A L - 6 specimens preserved as sl ightly compressed in ternal moulds in siltstone or flattened impressions in shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H 610H/1 89 36.2 40.7 30.5 610B/1 78 30.5 39.1 33 6 1 1 M / 2 75.5 27 35.7 29.0 704D/1 49.6 18.0 36.3 19.0 6 0 9 A / 1 49 18 36.7 19.5 2 4 B / 1 37.8 13.3 35.2 14.8 D E S C R I P T I O N - V e r y evolute form of m e d i u m size. W h o r l expansion moderately rapid, turning into egression at mature stage. W h o r l section ellipsoid, compressed, flanks sl ightly convex. F ine , dense, prorsiradiate r ibbing strongest on inner whorls. D I S C U S S I O N - Specimens 610B/1 and 2 4 B / 1 show the best agreement wi th the holotype. The other specimens are worn internal moulds lacking ornament or flattened impressions identified as E. cf. tasekoi. Our largest specimen show egression at a diameter over 75 m m comparable to FREBOLD's E. cf. tasekoi (1967, p i . 6, fig. 1) which develops egression at a diameter of approximately 125 m m . Shallow constrictions are only rarely preserved on our individuals . S Y S T E M A T I C P A L E O N T O L O G Y LYTOCERATINA 84 O C C U R R E N C E - Kennecot t Point , Section D and F ; K u n g a Island, Section S; from the Canadensis Zone. D I S T R I B U T I O N - E. tasekoi was first described from the Canadensis Zone of the Taseko Lakes area ( F R E B O L D , 1967) and it is also reported from Nevada ( G U E X and T A Y L O R , 1976, T A Y L O R , 1990). Eolytoceras ? guexi ? T A Y L O R , M S name PI. 2, F i g . 3, 7-8 T Y P E - Holotype: Eolytoceras guexi T A Y L O R , in prep.; Specimen No. B7057/1 , deposited in the Northwest M u s e u m of N a t u r a l His tory , Por t l and . M A T E R I A L - 10 specimens, flattened impressions, compressed internal moulds and an external mould preserved i n shale and siltstone. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W 609D/1 127 40 31.5 45.8 6 611G/3 125 41.5 33.2 50.1 6 609G/1 86 29 33.7 34.5 5 6101/3 79.2 33.6 42.4 24.7 6 610G/6 80.2 28.5 35.5 26.5 6 Holotype 75 30.5 40.6 25 4 D E S C R I P T I O N - V e r y evolute shell at taining large size. Expans ion rate moderate to high. F lanks convex, whorls probably inflated. N o ornament seen on innermost whorls, adorally sl ightly convex flares developing from an early stage. 5-6 flares per half whor l at an umbi l ica l diameter greater than 25 m m . Ventro- la teral nodes or bullae developing on ventro-lateral termination(?) of flares at later growth stage. Flares may be S Y S T E M A T I C P A L E O N T O L O G Y LYTOCERATINA 85 accompanied by a flanking constr ict ion. Some specimens bearing fine riblets especially on upper flank at large diameter. N o sutures available. D I S C U S S I O N - The identification remains tentative as the holotype from Nevada shows more slowly enlarging whorls and less conspicuous constrictions instead of the prominent flares seen on the Queen . Charlot te specimens (although this may be due to preservational differences). The diagnostic ventro-lateral nodes provide strong support for regarding them conspecific. E. tasekoi differs from E. ? guexi ? in having r ibbed inner whorls, less well developed constrictions and lacking ventro-lateral nodes. O u r individuals are also similar to several specimens of Analytoceras articulatum (SOWERBY) figured by WAHNER (1894, especially p i . 54, fig. 3, and p i . 58, fig. 1-3) in their outer whorls bearing flares and nodes. Nonetheless A. articulatum can be easily distinguished by its "art iculated" inner whorls (divided by deep constrictions) most clearly seen on juvenile specimens. The two species are probaly not far removed, however. For the above affinities the generic assignment to Eolytoceras is tentative the confirmation pending on comparison of sutures not available on the studied specimens. O C C U R R E N C E - Kennecot t Po in t , Section D and F , from the Canadensis Zone. D I S T R I B U T I O N - Besides the Queen Charlot te Islands, E. guexi is only known from the Canadensis Zone of Nevada. S Y S T E M A T I C P A L E O N T O L O G Y SCHL O THEIMIID A E 86 S U B O R D E R A M M O N I T I N A H Y A T T , 1889 S U P E R F A M I L Y P S I L O C E R A T A C E A E H Y A T T , 1867 F A M I L Y S C H L O T H E I M I I D A E S P A T H , 1923 G E N U S Angulaticeras Q U E N S T E D T , 1883 T Y P E S P E C I E S - Ammonites lacunatus J . B U C K M A N , 1844; subsequent designation by L A N G E (1924) ( I C Z N Op in ion 324). S Y N O N Y M Y - Argoceras STEINMANN, 1925; Boucaulticeras S P A T H , 1924; Pseudoschlotheimia S P A T H , 1924 (DONOVAN et al . , 1981). D E S C R I P T I O N - Involute shell of usually small to medium size wi th rap id ly enlarging whorls of high oval section. V e n t r a l sulcus well developed in juvenile stage, becoming less pronounced on adults. Ornament of fine and dense sigmoid ribs not crossing the venter. Characterist ic irregular al ternation of bifurcating and intercalat ing ribs. V e n t r a l rib ends often accentuated. R E M A R K S - Recently BLOOS (1979, 1988) commented on the generic systematics employed by D O N O V A N and F O R S E Y (1973) and subsequently by D O N O V A N et al. (1981). F i r s t he emphasized the heterogenous nature of the closely related genus Sulciferites by using quotation marks (BLOOS, 1979). Later he favoured the unif icat ion of Sulciferites and Angulaticeras under the latter generic name on the basis of similar su tura l characteristics as already pointed out by SCHINDEWOLF (1962). D O N O V A N and F O R S E Y ' s twofold grouping is largely based on external morphology: Angulaticeras being more finely and densely r ibbed having a ventral sulcus while Sulciferites possesses coarser r ibbing. Th i s classification is retained here. S Y S T E M A T I C P A L E O N T O L O G Y SCHLOTHEIMIIDAE 87 A G E A N D D I S T R I B U T I O N - Angulaiiceras occurs in Europe in both the Mediterranean and the Northwest European provinces in the Lower and Upper S inemur ian . Outside Europe it has been recorded from N o r t h and South A m e r i c a from the same age range. Angulaiiceras spezianum (CANAVARI, 1882) PI. 3, F i g . 5 * 1882 Aegoceras Spezianum n . sp. - CANAVARI, p. 167, p i . 18, fig. 12a-c 1889 Schlotheimia Speziana CANAVARI - HYATT, p. 136 M A T E R I A L - One flattened internal mould of mediocre preservation in shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W U R H W V U R R 724D/1 18.1 5.0 27.6 9.1 13 26 2.0 D E S C R I P T I O N - Smal l , moderately involute form w i t h rapidly enlarging whorls and narrow umbil icus. A s far as preservation allows observation umbi l i ca l wa l l low, umbi l ica l shoulder rounded, and flanks convex. Dense, sharp, straight, and gently prorsiradiate ribs appear to originate on umbi l i ca l wal l and terminate ventrally in incipient nodes. Bifurcat ion occurs near the umbi l ica l shoulder, alternation of simple, bifurcating and intercalatory ribs somewhat irregular. D I S C U S S I O N - Th i s specimen is in remarkable agreement wi th the original of CANAVARI (1882). W i t h i n the group of Angulaiiceras occurring in the Upper Sinemurian A. spezianum is distinguished from A. geyeri (HYATT, 1889; the original of which is "Schlotheimia lacunaia" in GEYER, 1886, p. 259, p i . 3, fig. 22-23) mainly by its straight ribs; from A. angustisulcaium fGEYER, 1886) and the very similar A. dumortieri (FUCINI, 1903) also by its less numerous ribs; whereas A. ventricosum has slightly coarser and more sigmoid S Y S T E M A T I C P A L E O N T O L O G Y SCHL O THEIMIID A E 88 r ibb ing . In addit ion, the incipient nodes at the ventral terminat ion of ribs is another characteristic feature of A. spezianum. O C C U R R E N C E - Tasu Sound area, Section P , Level 4; from the A r n o u l d i Zone. D I S T R I B U T I O N - Previously this species has only been described from L a Spezia, Nor the rn Appenines , Italy, probably from the Upper Sinemurian. Angulaiiceras cf. ventricosum ( S O W E R B Y , 1831) PI. 3, F i g . 9 cf. pars 1856 Ammonites Moreanus d ' O R B . - H A U E R , p. , p i . 15, fig. 3-4 (non fig. 1-2) cf. 1882 Aegoceras ventricosum SOW. sp. - C A N A V A R I , p. 165, p i . 18, fig. 10-11 cf. pars 1886 Aegoceras ventricosum SOW. ( C A N A V . ) - W A H N E R , p. 186, p i . 23, fig. 4-7, 9, 12 (non fig. 8, 10, 11) non 1963 Angulaiiceras ventricosum (SOW.) - BLIND, p. 81, p i . 1, fig. 17 (=Schlotheimia sp. indet. (BLOOS, 1979, p. 147, p i . 1, fig. 9)) cf. .1976 Sulciferites ventricosus (SOW. 1833) - S C H L E G E L M I L C H , p. 37, p i . 7, fig. 6 cf. 1979 Angulaiiceras ventricosum ( S O W E R B Y 1831) - B L O O S , p. 145, p i . 1, fig. 1-8 non 1981 Angulaiiceras cf. ventricosum (SOW.) - H l L L E B R A N D T , p.504, p i . 2, fig. 2 ( = Sulciferites cf. trapezoidalis) cf. 1985 Angulaiiceras cf. ventricosum ( S O W E R B Y 1831) - PRINZ, p. 173, p i . 2, fig. 9 cf. 1987 Angulaiiceras ventricosum (SOWERBY) - QUINZIO SINN, p i . 3, fig. 6 cf. 1987 Angulaiiceras cf. ventricosum ( S O W E R B Y ) - QUINZIO SINN, p i . 3, fig. 5 M A T E R I A L - Three rather poorly preserved flattened internal moulds in shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W U R H W V U R R 6101 28.1 5.0 17.8 15.2 w lO , %18 1.8 606C/1 16.7 2.8 16.8 10.0 %20 2.20 705H/1 %34 8.4 %24 16.3 - - -S Y S T E M A T I C P A L E O N T O L O G Y SCHL O THEIMIIDAE 89 D E S C R I P T I O N - Involute shell of smal l size wi th rapidly enlarging whorls. Umbi l i cus narrow wi th rounded shoulder. N o information regarding the whor l section and ventral features can be deduced due to the bad preservation. Densely r ibbed, ribs sharp, s l ightly sigmoid, gently prorsiradiate. Bifurcat ion and intercalation of ribs common apparently without consistent pattern. Bifurcat ion occurs at various points from the umbi l i ca l shoulder to the lower flank. ' D I S C U S S I O N - BLOOS (1979) treated this species in detail refiguring some of WAHNER's (1886) specimens. The species displays a certain amount of var iabi l i ty in r ibbing (e.g. shape and density of ribs). The Queen Char lot te specimens occupy the straighter and coarser end of the spectrum. They are distinguished from Sulciferites trapezoidahs by their narrower umbil icus and finer sigmoid r ibbing. O C C U R R E N C E - Kennecot t Poin t , Section A , Level 1; Section D , Level 2; from the Canadensis Zone; K u n g a Island, Section T , Level 6; from the "Coroniceras" Zone. D I S T R I B U T I O N - In Te thyan Europe (Eastern A l p s , Appenines) from the Rotiforme Zone (sensu WAHNER, 1886), in northwest Europe from not lower than the Buck land i Zone. The upper l imit of range is not precisely known, but not higher than O b t u s u m Zone (BLOOS, 1979). A l so recorded from the Buck land i and Semicosta tum Zone of Chi le and Pe ru (RlCCARDI et al, 1990). G E N U S Sulciferites SPATH, 1922 T Y P E S P E C I E S - Ammonites sulcatus J . BUCKMAN, 1844 (non SIMPSON) (=Schlotheimia sulcifera S. BUCKMAN, 1911). For details see BLOOS, 1979, p. 150. S Y N O N Y M Y - Charmasseiceras SPATH, 1924; Encycloceras BLIND, 1963; Hongkongites GRABAU, 1928. S Y S T E M A T I C P A L E O N T O L O G Y S CHL O THEIMIID A E 90 D E S C R I P T I O N - Involute forms, variable in size. Strongly r ibbed, bifurcating and intercalatory ribs common. V e n t r a l sulcus may be present at early growth stage but disappears on adults. Interrupt ion of ribs pronounced on juveniles gradually changing to ribs crossing the venter. R E M A R K S - The status of Sulciferites and the closely related Angulaiiceras is problematic . Despite the objections expressed by BLOOS (1979, 1988) the classification of DONOVAN and FORSEY, 1973 is retained here (for further discussion see Remarks under Angulaiiceras). Ironically, wi th this practice most of the species belonging to Sulciferites does not have a characteristic ventral sulcus to which their generic name refers. A G E A N D D I S T R I B U T I O N - Sulciferites is widely dis t r ibuted in the uppermost Hettangian(?)-Lower Sinemurian wi th occurrences in Europe (both the Medi terranean and Northwest European province), the Himalayas, Ch ina , Indonesia, N o r t h and South Amer i ca . Sulciferites marmoreus (OPPEL, 1862) PI . 3, F i g . 8 * 1856 Ammonmites Charmassei D'ORBIGNY - HAUER, p. 49, p i . 14, fig. 1-3 1862 Ammonmites marmoreus n . sp. - OPPEL, p. 130, footnote 1878 Aegoceras tenuicostatum n . sp. - HERBICH, p. 110, p i . 20D, fig. 3a-b 1878 Aegoceras Charmassei D'ORBIGNY - HERBICH, p. 110, p i . 20D, fig. 2a-b 1886 Aegoceras marmoreum OPP. - WAHNER, p. 180, p i . 22, fig. 1-5 1908 Schlotheimia marmorea OPP. - VADASZ, p. 363 ? 1908 Schlotheimia sp. ind . aff. marmorea OPPEL - DlENER, p. , p i . 15, fig. 5 1963 Schlotheimia marmorea (OPPEL) - BLIND, p. 80, p i . 2, fig. 5 ? 1963 Schlotheimia (Angulaiiceras) curvata n . sp. - BLIND, p. 82, p i . 1, fig. 23 cf. 1963 Schlotheimia (Angulaiiceras) haryicostata - BLIND, p. 83, p i . 1, fig. 19 non 1967 Charmasseiceras marmoreum (OPPEL) - FREBOLD, p. 27, p i . 3, fig. l a - d , 4a-b,; p i . 4, fig. 1, 2a-c 1983 Schlotheimia marmorea (OPPEL) - BLOOS, p. 129, fig. 2, 3 cf. 1984 Schlotheimia marmorea (OPPEL) - BRAGA et al. , p. 273, p i . 1, fig. 10-11 1988 Angulaiiceras marmoreum (OPPEL) - BLOOS, p. 6, p i . 1-3; p i . 4, fig. 7-8; p i . 5-8; p i . 9, fig. 1, text-fig. 3-11 ? 1989 Sulciferites cf. marmoreum (Oppel) - RlCCARDI et a l , p i . 2, fig. 1-2 S Y S T E M A T I C P A L E O N T O L O G Y S CHL O THEIMIIDA E 91 T Y P E - Holotype: original of HAUER, 1856, p i . 14, fig. 1-3, deposited in the Geologische Bundesanstal t , V i e n n a . M A T E R I A L - One specimen, relatively well preserved as flattened internal mould in shale. M E A S U R E M E N T S -S P E C I M E N N O . D M A X U D U W H P R H W U R H W V U R R 609E/4 114.3 36.4 31.8 46.0 17 28 1.65 %85.7 23.4 27.3 %41.7 13 28 2.15 17.6 11 26 2.36 10.5 12 21 1.75 D E S C R I P T I O N - Large, rather evolute form wi th moderately enlarging whorls and wide umbil icus . Strongly r ibbed; sl ightly sigmoid ribs start at umbi l i ca l shoulder broadening toward the venter. V e n t r a l rib ends accentuated at early growth stage suggesting that ribs do not cross the venter. R ibb ing pattern somewhat irregular, common bifurcating and intercalat ing ribs, height of furcation point and origin of secondary ribs varies from lower to middle flank. D I S C U S S I O N - The species was the subject of a recent revision (BLOOS, 1988). Its assignment to Sulciferites here is based on morphological similari t ies wi th the "charmassei"-grouTp (in much the same sense as SPATH's genus Charmasseiceras) which was lumped into the genus Sulciferites by DONOVAN and FORSEY (1973). Our specimen is sl ightly more evolute and more rapidly expanding than the average but otherwise it is close to several figured specimens inc lud ing the holotype. The specimen falls well wi th in the remarkable var iabi l i ty of this species as i l lustrated by BLOOS (1988). O C C U R R E N C E - Kennecot t Po in t , Section D , Level 20; from the Canadensis Zone. S Y S T E M A T I C P A L E O N T O L O G Y S CHL O THEIMIID A E 92 D I S T R I B U T I O N - In Europe in both provinces: in the Mediterranean province (Eastern A l p s , Betic Cordi l le ra , Transylvania) from the Marmoreus Zone (controversially uppermost Sinemurian and/or lowermost Sinemurian, see discussion in Chapter 3) and in northwest Europe ( S W Germany) from the topmost Hettangian (Angu la t a Zone, Depressa Subzone). S. marmoreus, or at least closely related forms, were recorded from Te thyan areas outside Europe (the Himalayas and R o t t i Island, Indonesia) ( G U E X and T A Y L O R , 1976). A comparable form occurs in the Canadensis Zone of Argen t ina ( R l C C A R D I et al . , 1989). Sulciferites cf. trapezoidalis ( S O W E R B Y , 1831) PI . 3, F i g . 2-3 cf. 1882 Aegoceras trapezoidale S O W . sp. - C A N A V A R I , p. 165, p i . 18, fig. 8-9 cf. pars 1886 Aegoceras trapezoidale S O W . ( C A N A V . ) - W A H N E R , p. 185, p i . 23, fig. 1-3 (non fig. 4) cf. 1908 Schlotheimia trapezoidale S O W . sp. - V A D A S Z , p. 365 ? 1908 Schlotheimia sp. ind . ex aff. trapezoidalis (SOW.) C A N . - D l E N E R , p. , p i . 15, fig. 2 cf. 1963 Schlotheimia (Encycloceras) trapezoidalis (SOW.) - BLIND, p. 81, p i . 1, fig 21 cf. 1979 "Sulciferites" trapezoidalis ( S O W E R B Y 1831) - B L O O S , p. 160, p i . 2, fig. 4 cf. 1981 Angulaticeras cf. ventricosum (SOW.) - H l L L E B R A N D T , p.504, p i . 2, fig. 2 non 1987 Sulciferites cf. trapezoidalis ( S O W E R B Y ) - QUINZIO SINN, p i . 2, fig. 7 (=Sulciferites cf. posttaurinus ( W A H N E R , 1886)) M A T E R I A L - 9 specimens of very poor to mediocre preservation, flattened impressions in shale and siltstone.. M E A S U R E M E N T S -S P E C I M E N N O . D M A X U D U W H P R H W U R H W V U R R 6 1 0 A / 6 23.0 5.5 23.9 12.3 9' 18 2.0 605C/1 29.3 6.6 27.7 12.5 9 17 1.88 609D/12 30.8 7.0 22.7 12.4 11 20 1.82 S Y S T E M A T I C P A L E O N T O L O G Y S CHL O THEIMIIDAE 93 D E S C R I P T I O N - Smal l , involute form wi th narrow umbil icus. Strongly r ibbed; ribs sharp, gently prorsiradiate, almost straight or slightly curved forward. Bifurcat ion of ribs occur near the umbi l ica l shoulder, intercalat ing ribs also present. D I S C U S S I O N - T h e studied specimens differ somewhat from other figured mater ial by having more commonly bifurcating ribs. Other characteristics agree reasonably well. S. trapezoidalis differs from the s imilar ly small and involute Angulaticeras ventricosum by its straighter and less dense ribs and wider umbil icus . Another related form is S. posttaurinus which can be distinguished by its coarser and blunter r ibbing. O C C U R R E N C E - Kennecot t Poin t , Section D , Level 1, 11, 12, 21;, Section F , Level 5 and 20; from the Canadensis Zone. D I S T R I B U T I O N - S. trapezoidalis is known from the Mediterranean province in Europe (Nor thern Appenines , Eastern A l p s , Transsylvania) , where available stratigraphic information suggests Marmoreus Zone. Outside Europe a specimen from the Coasta l Cord i l l e ra of C h i l a may be referred to this species ("Angulaticeras cf. ventricosum" of H l L L E B R A N D T , 1981). Sulciferites ? sp. PI . 3, F i g . 6 v. ? 1967 Charmasseiceras marmoreum ( O P P E L ) - F R E B O L D , p. 27, p i . 3, fig. l a - d , 4a-b,; p i . 4, fig. 1, 2a-c v. ? 1985 Boucaulticeras boucaultianum (D 'ORBIGNY) - O'BRIEN, p. 32, p i . 5, fig. 4 M A T E R I A L - 5 poorly preserved flattened internal moulds in shale. S Y S T E M A T I C P A L E O N T O L O G Y SCHL O THEIMIID A E 94 M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W U R H W V U R R 704F/7 44.1 %8.6 %19.5 %23.6 « 1 4 %27 %1.93 610D/11 53.6 %11 ss20.5 %26.4 - %30 --D E S C R I P T I O N - M e d i u m size, midvolute individuals wi th relatively narrow umbil icus . Densely r ibbed wi th gently prorsiradiate ribs which slightly curved forward. The poor preservation obliterates the r ibb ing pattern, but bifurcation frequently occurs on the lower flank. Intercalating ribs less numerous. D I S C U S S I O N - Our material appears to be most closely resembling par t icular ly in r ibbing style to the form described as "Charmasseiceras marmoreum" by FREBOLD, 1967 in spite of the difference in size. The r ibbing density of this form consistently exceeds that of Sulciferites marmoreus to such extent that they are probably not conspecific. The Queen Char lot te material , i f indeed conspecific wi th the individuals from Tyaughton Creek area, may consist of inner whorls, or alternately, microchonchs, whereas the large individuals from the latter locali ty may represent macroconhs as the fading of r ibb ing suggests. D imorph i sm in schlotheimids was postulated by CALLOMON (1981) wi th special reference to some giant forms. For comparison, Frebold 's specimen (pi . 4, fig. 1) has a whorl height of 129 m m and an estimated diameter of 360 mm. S. ? sp. is clearly dist inguished from Angulaiiceras boucaultianum by its wider umbil icus and coarser r ibbing. O C C U R R E N C E - Kennecot t Po in t , Section D , Level 21, 23, 24; K u n g a Island, Section S, Level 6; from the Canadensis Zone. D I S T R I B U T I O N - The synonymized form occurs in the Tyaugh ton Creek area (southern B r i t i s h Columbia) in the Canadensis Zone. S Y S T E M A T I C P A L E O N T O L O G Y S CHL O THEIMIID A E 95 F A M I L Y A R I E T I T I D A E HY A T T , 1875 S U B F A M I L Y A L S A T I T I N A E S P A T H , 1924 G E N U S Sunrisites G U E X , 1980 T Y P E S P E C I E S - Sunrisites sunnsense G U E X , 1980, by original designation. D E S C R I P T I O N - Relat ively evolute forms, whorl section subrectangular to ell ipsoid, wider than high. Venter bearing no keel. Coarsely r ibbed wi th blunt , rectiradiate ribs fading out or giving rise to faint secondary ribs before reaching ventro-lateral shoulder. A G E A N D D I S T R I B U T I O N - The type species occures in the Upper Het tangian (Morganense to Oregonense zones sensu T A Y L O R , in prep.) of Nevada. S. hadroptychus ( W A E H N E R , 1886), the other species originally assigned to the genus, was described from the Megastoma Beds of the A u s t r i a n A l p s (WAHNER, 1886) and probably also occurs in the Upper Hettangian of Nevada ( G U E X , 1980). Sunrisites ? senililevis n . sp. PI. 5, F i g . 5, 9 T Y P E - Holotype: G S C Specimen No. C-143327/c. Paratype: Specimen 611N/1 . T Y P E L O C A L I T Y - Castle Pass near Tyaugh ton Creek, Taseko Lakes area, B r i t i s h Co lumbia , G S C locality C-143327. Fo r the paratype see Occurrence below. T Y P E . H O R I Z O N - Basa l part of Canadensis Zone. SYSTEMATIC PALEONTOLOGY ALSA TITINAE 96 ETYMOLOGY - senihlevis (Latin "old smooth") refers to the smooth outer whorl of the holotype. MATERIAL - 1 poorly preserved external mould from the Queen Charlotte Islands. The holotype is a well preserved, though fragmentary internal mould with some shelly material. MEASUREMENTS SPECIMEN NO. DMAX UD U WH WW PRHW C143327/C (Holotype) 159 61.5 41.1 39 59.5 58.0 10 611N/1 (Paratype) 67 31 46.3 22 - 9 DIAGNOSIS - Moderately evolute form of large adult diameter. Whorl section ellipsoid. Inner whorls coarsely ribbed, ribs blunt, rectiradiate. Last whorl becoming smooth. Figure 6-3 Cross section of the holotype of Sunrisites senihlevis at DMAX=159 mm S Y S T E M A T I C P A L E O N T O L O G Y ALSA TITINAE 97 D E S C R I P T I O N - Midvo lu te species at taining large size. W h o r l section ellipsoid, whorls sl ightly compressed at juveni le stage, later becoming more inflated wi th nearly equal w id th and height (F ig . 6-3). Largest w id th located at lower th i rd of flank. U m b i l i c a l wal l high and steep, umbi l ica l shoulder rounded. Flanks convex, venter bearing no keel. Coarsely costate up to an umbi l ica l diameter of cca. 40 m m , where ribs fade out rather abrupt ly, last whor l smooth. R ibs widely spaced, rectiradiate, blunt , having a high but rounded profile. R i b frequency nearly constant at 8-10 ribs per half whor l . Ribs strongest at mid flank, fading out abrupt ly at ventro-lateral shoulder without crossing venter. D I S C U S S I O N - The asssignment of the new species to Sunrisites is based on its coarse, upright r ibb ing , evolute inner whorls, and non keeled venter. It exceeds in size, however, every known representatives of the genus and shows a remarkable tendency to become more involute and lose ornament at matur i ty . These may be interpreted as d imorph characters of a macroconch or s imply the holotype may represent a rare mature specimen. The new species can be distinguished from 5". sunrisensis by its substantial ly larger size, coarser and less dense costation, and ellipsoid whor l section. S. hadroptychus differs mainly by being more evolute, retaining costation at comparable large diameters, and showing a tendency of flexuous r ibbing. O C C U R R E N C E - Kennecot t Poin t , Section F , Level 6; from the lower part of Canadensis Zone. D I S T R I B U T I O N - The only two known individuals are the holotype and the Queen Charlot te specimen, bo th from the lower part of the Canadensis Zone from Tyaughton Creek and Kennecott Poin t , respectively. S Y S T E M A T I C P A L E O N T O L O G Y ALSA TITINAE 98 G E N U S Badouxia GUEX and TAYLOR, 1976 T Y P E S P E C I E S - Psiloceras canadense FREBOLD, 1951 by original designation (GUEX and TAYLOR, 1976, p. 525). D E S C R I P T I O N - Midvo lu t e forms wi th rounded to ellipsoid whorl section. R i b b i n g gently prorsiradiate, strong on lower flank and fading but ventral ly on some species, crossing venter by forming a chevron of weak pr imary or faint secondary ribs on others. Sutures relatively simple. R E M A R K S - The genus was originally considered a schlotheimhd (GUEX and TAYLOR, 1976), but later it was transferred to Alsa t i t inae as an Alsatites-Sunrisites-Badouxia evolutionary lineage was recognized (GUEX, 1980). Besides the species original ly assigned to the genus (B. canadensis and B. columbiae (FREBOLD, 1967)) B. occidentals (FREBOLD, 1967) and B. oregonensis (TAYLOR, M S name) are also included herein. Psiloceras reissi TlLMANN, 1917 was also proposed to be a Badouxia (QUINZIO SINN, 1987) but it is more l ikely to represent a Discamphiceras based on its r ibbing pattern ( m a x i m u m strength of ribs at mid flank) ( D . TAYLOR, pers. comm., 1991). A G E A N D D I S T R I B U T I O N - Badouxia is widely dis t r ibuted around the Pacific margins wi th occurrences in Alaska , B r i t i s h C o l u m b i a , Oregon, Nevada, Pe ru , Chi le , and Northeastern Siberia (TAYLOR et al. , 1984). Its stratigraphic posit ion has been controversial, herein interpreted as uppermost Het tangian to basal Sinemurian (see Chapter 3 for details). Badouxia canadensis (FREBOLD, 1951) PI. 5, Fig. 1-2, 6 * v pars 1951 Psiloceras canadense sp. nov. - FREBOLD, p. 3, p i . 4-6; p i . 2, fig. 1; p i . 3, fig. 1 (non pi . 1, fig. 1-3 = Badouxia oregonensis) S Y S T E M A T I C P A L E O N T O L O G Y ALSATITINAE 99 1962 Waehneroceras sp. - CORVALAN, p. 158, p i . 1, fig. 4 1964 Psiloceras canadense F rebold - FREBOLD, p. 6, p i . 1, fig. 1-5 v 1967 Psiloceras canadense Frebold - FREBOLD, p. 18, p i . 1, fig. 1-3 1981 Caloceras canadense FREBOLD - HlLLEBRANDT, p. 503, p i . 1, fig. 5 1981 Badouxia canadensis (FREBOLD) - IMLAY, p. 31, p i . 2, fig. 18-21, 24-28 1985 Psiloceras canadense (FREBOLD) - PRINZ, p. 188, p i . 2, fig. 4 1987 Badouxia cf. canadensis (FREBOLD) - QUINZIO SINN, p i . 1, fig. 11 1989 Badouxia canadensis (Frebold) - RlCCARDI et a l , p i . 2, fig. 3-4 T Y P E - Holotype: Psiloceras canadense FREBOLD, 1951, p. 3, p i . 1, fig. 4; G S C Type No. 11206. M A T E R I A L - A large number of specimens preserved mostly as flattened impressions or internal moulds wi th the exception of a few less compressed internal moulds. M E A S U R E M E N T S - A sample of 20 specimens were measured from a single bed (Section F , Level 14) Scatter diagrams of U D vs. D M A X and P R H W vs. U D are given in F i g . 6-5 and 6-6, respectively. SYSTEMATIC PALEONTOLOGY ALSA TITINAE 100 UD ( m m ) 30 -i 20 — 10 — Badouxia canadensis o Badouxia columbiae J o eP o • o o »o° 0 20 40 DMAX ( m m ) Badouxia canadensis: n=20 y=0.365x-0.02 r=0.92 Badouxia columbiae: n=18 y=0.361x-0.98 r=0.81 60 80 Figure 6-4 Scatter diagram of umbilical diameter (UD) vs. maximum diameter (DMAX) of Badouxia canadensis and Badouxia columbiae, both based on samples 20 of specimens from two localities (Section F, Level 14 and Section F, Level 19, respectively) DESCRIPTION - Midvolute form of medium size, diameter not exceeding 8 cm. Umbilicus moderately wide, tipically representing 35-40% of diameter. Whorls enlarging moderately rapidly, overlapping 30 to 50% of the preceeding one. Whorl section rounded to ellipsoid. Umbilical wall steep and high, umbilical shoulder well defined but rounded. Flanks slightly convex, venter non keeled. Strong, prorsiradiate ribbing confined to lower and middle flank, fading out on upper flank. A tendency of weakening of ribs at larger size may be noticeable. Rib frequency increasing slightly but steadily with diameter, number of ribs at an umbilical diameter of 20 mm commonly 14-16. DISCUSSION - The species exhibits considerable variability in volution and ribbing strength. B. oregonensis and B. columbiae seem to be closely related to B. canadensis. The first differs mainly by its more slowly SYSTEMATIC PALEONTOLOGY ALSATITINAE 101 PRHW 20 10 5 • «• •• • • • • • • o o > o o • m»om oca WOOD OO I o o a» I • o o o o o D O O 1 o o o o B a d o u x i a c a n a d e n s i s B a d o u x i a o « c o l u m b i a e i i i i I l l l I l l l 0 10 20 30 U D ( m m ) Badouxia canadensis: n=49 y=0.226x+10.54 r=0.63 Badouxia columbiae: n=31 y=0.338x+11.70 r=0.56 Figure 6-5 Scatter diagram of rib frequency (PRHW) vs. umbilical diameter (UD) of Badouxia canadensis and Badouxia columbiae. Samples as in Fig. 7-3. expanding whorls, slightly wider umbilicus, smaller whorl height, less well defined umbilical wall and shoulder as well as less prorsiradiate ribbing whereas the latter can be distinguished by its slightly denser costation (Fig. 7-4) consisting of ribs not fading out on the upper flank but being projected forward instead. Statistical studies supporting the separation of B. canadensis and B. columbiae are presented by O'BRIEN (1985). OCCURRENCE - Kennecott Point, Sections D, F, G; Kunga Island, Section S; from the Canadensis Zone. DISTRIBUTION - B. canadensis is characteristic of the Canadensis Zone in North America, which is thought to correlate with the uppermost Hettangian - basal Sinemurian (see Chapter 3 for details). It has only been found in allochtonous terranes, not on the craton. Other occurrences around the Pacific margin S Y S T E M A T I C P A L E O N T O L O G Y ALSA TITINAE 102 include Peru (PRINZ, 1985), Chi le (HlLLEBRANDT, 1981, QUINZIO SINN, 1987), Argen t ina (RlCCARDI et a l , 1989), and Northeast Siber ia (REPIN, 1977). Badouxia columbiae (FREBOLD, 1967) PI. 4, F i g . 3; PI . 5, F i g . 3-4, 8 v 1951 Schlotheimia (Scamnoceras) cf. S. acuticosta - FREBOLD, p. 6, p i . 4, fig. 1 v ' 1951 Schlotheimia (?) sp. indet. - FREBOLD, p. 7, p i . 4, fig. 2-4 * v pars 1967 Psiloceras (Curviceras) columbiae n . sp. - FREBOLD, p. 20, p i . 1, fig. 10; p i . 2, fig. 10; p i . 3, fig. 2; text-fig. 5 (non p i . 2, fig. 1) ? 1981 Badouxia columbiae (FREBOLD) - IMLAY, p. 31, p i . 2, fig. 22-23 T Y P E - Holotype: Psiloceras (Curviceras) columbiae FREBOLD, 1967, p. 20, p i . 2, fig. 2; G S C T y p e No . 19925. M A T E R I A L - A large number of specimens preserved mostly as flattened impressions or internal moulds wi th the exception of a few less compressed internal moulds. M E A S U R E M E N T S - 20 specimens were measured from a single bed (section F , level 19) to represent a populat ion. Scatter diagrams of U D vs. D M A X and P R H W vs. U D are given in F i g . 6-4 and 6-5, respectively. D E S C R I P T I O N - M i d v o l u t e form of med ium size. Umbi l i cus representing 30-40% of diameter. Whor l s enlarging moderately rapidly . W h o r l section rounded at an early stage becoming ellipsoid wi th height exceeding wid th at adult stage. U m b i l i c a l wal l steep, umbi l ica l shoulder well defined but rounded. Strongly costate, ribs prorsiradiate, projected forward near ventro-lateral shoulder. Their trend on venter not seen due to poor preservation. Number of ribs per half whorl at an umbi l ica l diameter of 15 m m is commonly 16-18. S Y S T E M A T I C P A L E O N T O L O G Y A L SA TI TIN A E 103 D I S C U S S I O N - The differences between B. columbiae and B. canadensis are discussed under B. canadensis. O C C U R R E N C E - Kennecott Point , Sections D , F , G ; K u n g a Island, Section S; from the upper part of Canadensis Zone. D I S T R I B U T I O N - B. columbiae is known to occur in the Taseko Lakes area (FREBOLD, 1967), A l a s k a (IMLAY, 1981) and Nevada (TAYLOR, 1986, 1990, in prep.). Badouxia oregonensis TAYLOR, M S name PI. 4, F i g . 1-2 v pars 1951 Psiloceras canadense n . sp. - FREBOLD, p. 3, p i . 1, fig. 1-3 only T Y P E - Badouxia oregonensis, TAYLOR, in prep., Specimen No . B 7038/1, deposited in the Northwest M u s e u m of Na tu ra l History, Por t l and . M A T E R I A L - 6 specimens preserved as impressions or flattened external / in ternal moulds in shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W 617E 48.8 24.0 49.2 15.7 14 6 0 4 A / 5 28.3' 13.5 47.7 7.3 13 617D/1 24.2 11.0 45.5 7.1 12 D E S C R I P T I O N - Moderately evolute form of smal l to med ium size. Umbi l i cus relatively wide representing nearly one half of diameter. Whor l s expanding slowly, embracing about one t h i rd of the preceeding one. W h o r l section rounded, umbi l ica l wall indis t inct . Costa t ion consisting of gently prorsiradiate ribs strongest S Y S T E M A T I C P A L E O N T O L O G Y ALSATI TINA E 104 on the lower two th i rd of flank and fading out on the upper flank. R ibb ing frequency increasing li t t le wi th size. D I S C U S S I O N - Some of the smaller paratype.s of FREBOLD's B. canadensis (1951, p i . 1, fig. 1-3) can be interpreted as B. oregonensis based on the differences listed under B. canadensis. Ou r specimens agree well wi th the holotype. T h e larger individuals demonstrate that B. oregonensis can at tain a diameter of 5 cm. B. oregonensis is suggested to represent a t ransi t ional form between the closely related genera of Sunrisites and Badouxia (TAYLOR, in prep.). O C C U R R E N C E - Kennecot t Po in t , Sections D and F ; from the basal part of Canadensis Zone. D I S T R I B U T I O N - The holotype is described from the Oregonensis Assemblage of the Gray lock Format ion , Oregon (TAYLOR, i n prep.). The synonymized material is derived from the Canadensis Zone of the Taseko Lakes area (FREBOLD, 1967). Badouxia cf. occidentals (FREBOLD, 1967) PI . 3, F i g . 7, 10 * v cf. 1967 Psiloceras occidentale n . sp. - FREBOLD, p.19, p i . 1, fig. 4-5 T Y P E - Holotype: Psiloceras occidentale, FREBOLD, 1967, p. 19, p i . 1, fig. 4; G S C T y p e No . 20067. M A T E R I A L - 4 specimens preserved as flattened internal moulds in shale. S Y S T E M A T I C P A L E O N T O L O G Y ALSA TITINAE 105 M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H 611G 84.5 29 34.3 32.3 617E/6 ~75.5 26.5 35.0 27.1 D E S C R I P T I O N - Moderate ly involute form of m e d i u m size. Umbi l i cus representing nearly one th i rd of diameter. Whor l s enlarging rather rapidly overlapping 50-70%. W h o r l section not known from our specimens. Inner whorls coarsely r ibbed up to an umbi l i ca l diameter of 15 m m after which r ibb ing gradually fades through a phase where ribs are confined to lower flank. Ribs on inner whorls gently prorsiradiate. D I S C U S S I O N - The holotype shows an entirely smooth last whor l and the paratypes are r ibbed faintly on the first half of last whorl . Ou r specimens differ in losing costation through a stage characterized by ribs confined to the lower flank. A l s o r ibb ing on our individuals persists to s l ight ly larger umbi l ica l diameters and the whorl expansion rate is somewhat higher. O C C U R R E N C E - Kennecott Poin t , Sections D and F; from the Canadensis Zone. D I S T R I B U T I O N - Previously B. occidentalis has only been known from the Canadensis Zone of the Taseko Lakes area (FREBOLD, 1967) and Nevada (TAYLOR, 1990). Badouxia aff. occidentalis (FREBOLD, 1967) PI. 4, Fig. 4 M A T E R I A L - One specimen preserved as a flattened internal mould . M E A S U R E M E N T S - Specimen No . 614C/1 D M A X = 2 8 . 7 U D = 7 . 8 U=27.1 W H = 1 1 . 3 S Y S T E M A T I C P A L E O N T O L O G Y ALSATI TINA E 106 D E S C R I P T I O N - Moderate ly involute shell of smal l size. A l though preservation is highly compressed, flanks appear to be flat our slightly convex. Inner whorls densely ribbed up to an umbi l i ca l diameter of approximate ly 4 m m where r ibbing disappears abrupt ly, last whorl entirely smooth. D I S C U S S I O N - A l t h o u g h the style of ornament warrants comparison wi th B. occidentalis, our specimen has a s l ight ly narrower umbil icus and probably different whor l section. Al so the r ibb ing ends significantly earlier than on the type material . Should our ind iv idua l represent a new species the decision must await the discovery of more and better preserved material . O C C U R R E N C E - Kennecot t Poin t , Section G , uppermost part of the Canadensis Zone. Badouxia ? sp. PI. 4, F i g . 5 v pars 1967 Psiloceras (Curviceras) columbiae n . sp. - FREBOLD, p. 20, p i . 2, fig. 1 only M A T E R I A L - One flattened internal and 1 flattened external moulds of poor preservation in shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W C-156952 151 42 27.8 63 _ 6 12 611N/2 >200 94 _ -9 10 FREBOLD,1967 >150 45 _ _ _ p i . 2, fig. 1 9 13 S Y S T E M A T I C P A L E O N T O L O G Y ALSATITINAE 107 D E S C R I P T I O N - Moderate ly involute shell of large size. Umbi l i cus relatively narrow, representing less than 30% of diameter. Whor l s expanding rapidly, overlapping nearly 40% of the preceeding one. W h o r l section not known due to inferior preservation. Inner whorls strongly r ibbed, ribs gently prorsiradiate. R i b b i n g persists up to an umbi l ica l diameter of 8-15 m m where it disappears abrupt ly, remaining outer whorls smooth. D I S C U S S I O N - Our mater ial shows a r ibbing style s imilar to B. occidentalis but it is substantial ly larger in size. A reasonable comparison can be drawn wi th one of the paratypes of B. columbiae (FREBOLD, 1967, p i . 2, fig. 1) which, however, possess a suture more complex than the holotype and other specimens of that species besides the remarkable difference in size and ornament. It is conceivable that these individuals represent a macroconch of a species of Badouxia. T o establish a d imorph relationship more and better preserved mater ia l wi th precise stratigraphic information is needed. O C C U R R E N C E - Kennecot t Po in t , Section D and F ; from the Canadensis Zone. F A M I L Y A R I E T I T I D A E HYATT, 1875 S U B F A M I L Y A R I E T I T I N A E HYATT, 1875 R E M A R K S - Th i s subfamily is mainly composed of genera wi th evolute, widely umbil icate shell, strong but simple r ibbing and keeled venter wi th the exception of Tmaegoceras which is distinguished by its lack of ornament. Arnioceras is defined by its smooth nucleus. The differentiation between the remaining genera wi th in this l imi ted morphological pool has been a source of controversy. A comparison between the generic classification used by ARKELL et al . (1957), GUERIN-FRANIATTE (1966), DONOVAN et al . (1981) and BLOOS (1988) reveals the contrasting views of different authors. F r o m our perspective a further problem arises from two-dimensionally preserved material . A s diagnostic ventra l features furnish the basis for dist inct ion between genera and subgenera it is pract ical ly impossible to safely conclude on the generic identi ty of much of our S Y S T E M A T I C P A L E O N T O L O G Y ARTE TI TINA E 108 mater ia l ( G . BLOOS, wri t ten comm., 1990). Paradoxical ly in some cases it is easier to establish specific ident i ty based pr imar i ly on characteristics of r ibbing and accept other authors ' generic assignment. Qual i ta t ive and quanti tat ive assessment of r ibbing together wi th volut ion provides the best clue for identif ication but the preservation sets serious l imits on the degree of accuracy. G E N U S Vermiceras HYATT, 1889 T Y P E S P E C I E S - Ammonites spiratissimus QUENSTEDT, 1883, subsequent designation by SPATH (1924). R E M A R K S - Vermiceras is used here in the sense of DONOVAN and FORSEY (1973) who include Paracaloceras as a subgenus. The main difference between Vermiceras s. str. and Paracaloceras is that the first possess only a shallow keel flanked by faint if any sulci whereas Paracaloceras may develop more strongly carinate-sulcate venter. Such differences are not easily determinable in most of our material hence the name Vermiceras is used as a convenience whilst acknowledging that Paracaloceras may be present in the Queen Charlot te Islands. A G E A N D D I S T R I B U T I O N - Vermiceras s. str. is most common in the Conybear i and Rotiforme Subzones of B u c k l a n d i Zone in Northwest Europe. It is also known from the B u c k l a n d i Zone in South A m e r i c a (RlCCARDI et a l , 1990). Paracaloceras is characteristic of the Medi terranean Province in Europe where several species from the Nor thern A l p s are i l lustrated by WAHNER (1886, 1888). Other Te thyan localities include the Himalayas and T i m o r (GUEX and TAYLOR, 1976). Paracaloceras was recently reported from the Canadensis Zone of Nevada (TAYLOR, 1990). S Y S T E M A T I C P A L E O N T O L O G Y A RIE TI TIN A E 109 Vermiceras cf. supraspiratum (WABHNER, 1888) PI . 6, F i g . 2 cf. 1882 Arietites spiratissimus Quenst . - CANAVARI, p. 177, p i . 20, fig. 2 c f 1888 Arietites supraspiratus n . f. - WAHNER, p. 298, p i . 20, fig. 6-9 T Y P E - Syntypes: WAHNER, p i . 20, fig. 6-9. M A T E R I A L - 3 specimens preserved as one-sided, compressed and somewhat weathered internal moulds. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W 6 0 4 A / 4 69.5 50.3 72 10.2 27 610H/11 61.5 41.5 67.5 10.4 27 D E S C R I P T I O N - M e d i u m size wi th extremely wide umbil icus representing approximately 70% of diameter. Flanks appear to be convex. Moderate ly densely r ibbed, rib frequency increasing steadily. Ribs rectiradiate, sl ightly concave ad orally. D I S C U S S I O N - The poor preservation prevents observation of venter and whor l section and renders an unambiguous identification impossible. Three groups wi th s imilar ly densely r ibbed serpenticone morphology can be considered: - F r o m the species i l lustrated by WAHNER (1886, 1888) V. supraspiratum shows nearly ident ical r ibbing style and density whereas "Arietites perspiratus" is more densely r ibbed and "Arietites proaries" possess more concave ribs. A m o n g the Nevadan forms current ly under study by D . TAYLOR, Paracdloceras morganense is also close to our forms but more densely r ibbed. S Y S T E M A T I C P A L E O N T O L O G Y A RIE TIT IN A E 110 - A m o n g the specimens of Vermiceras s. s t r , the r ibbing of V. scylla is pract ical ly indist inguishable from our form. However, its venter bears only a weak keelwhereas our specimens show traces of a more prominent keel. V. spiratissimum differs i n having straighter ribs. - Evolu te and densely r ibbed representatives of Metophioceras (e.g. M. janus, M. caesar, and M. longidomus) differ in having flattened flanks and tricarinate-bisulcate venter, characteristics not observed on the studied specimens. O C C U R R E N C E - Kennecott Point , Section D , Level 3 and 9, from the base of Canadensis Zone. D I S T R I B U T I O N - V. supraspiratum is known from the Nor thern Appenines , Italy, and Nor the rn A l p s , A u s t r i a . Accord ing to WAHNER (1888) it is derived from the Megas toma and Marmorea zones. Vermiceras ex gr. coregonense (SOWERBY, 1831) PI. 6, F i g . 1,5 M A T E R I A L - More than 50 specimens, the majority preserved as flattened impressions in shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W 611E/12 78 44 56.4 17.2 26 610J/6 61.5 35 56.9 12.4 26 611H/12 53 32 60.3 12.5 25 609D/9 50 24.5 49 13 25 609H/11 40.5 20 49.4 11.4 21 M e a n = . S tandard deviat ion= 54.4 4.98 S Y S T E M A T I C P A L E O N T O L O G Y A RIE TIT IN A E 111 D E S C R I P T I O N - Evolute form, diameter does not exceed 10 cm. Whor l s enlarging moderately slowly, umbil icus representing approximately 50-55% of diameter. F lanks appear to be somewhat convex, although flattened preservation prevents observing whor l section. Some specimens show trace of a rather prominent keel possibly flanked by sulci . Densely r ibbed; number of ribs 16-20 per half whor l at 10 m m , 20-25 at 20 m m umbi l i ca l diameter. Ribs rectiradiate, s l ightly concave adorally. D I S C U S S I O N - Due to the lack of information of ventral characteristics and whorl section a more accurate identification is not possible. The group of species to which comparison is made includes V. (P.) coregonense, V. (P.) grunowi (HAUER, 1856), V. (P.) multicostatum FREBOLD, 1967, and V. (P.) ? cordieri (CANAVARI, 1888). The rib frequency of selected specimens along wi th representatives of the listed taxa is given on Figure 6-6. The rib frequency by itself is inadequate to serve as a basis of dis t inct ion. FREBOLD's P. multicostatum differs from V. (P.) coregonense only by its more densely r ibbed innermost whorls, their rib frequency converges at larger diameter. Some of the Queen Char lot te specimens fall very close to V. (P.) multicostatum. SYSTEMATIC PALEONTOLOGY A RIE TIT IN A E 112 PRHW 30 -20 -10 -10 20 30 40 U D ( m m ) V. (P.) ex gr. coregonense V. (P.) coregonense V. (P.) coregonense Queen Charlotte specimens Neotype Selected specimens. Wanner 1888 V. (P.) grunowi Holotype V. (P.) cordieri Wanner 1888, pi. 18, fig.4 V. (P.) multicostatum Holotype V. ex gr. coregonense: n=17 y=0.35x+13.12 r=0.85 Figure 6-6 Rib frequency curves of 7 specimens of Vermiceras ex gr. coregonense from Kennecott Point plotted together with selected type specimens of closely allied species. OCCURRENCE - Kennecott Point, various levels in Sections D, F, and G; Kunga Island, Section S; from the lower and middle part of the Canadensis Zone. DISTRIBUTION - V. (P.) coregonense, V. (P.) ? cordieri, and V. (P.) grunowi are recorded from the Marmoreum Zone of the Mediterranean Province in Europe. V. (P.) grunowi is also known from Nevada (TAYLOR, 1990). V. (P.) coregonense or closely related forms occur in the Himalayas (DlENER, 1908) and Timor (ROTHPLETZ, 1892, KRUMBECK, 1923). V. (P.) multicostatum is reported from the Canadensis Zone of the Taseko Lakes area (FREBOLD, 1967). S Y S T E M A T I C P A L E O N T O L O G Y A RIE TIT IN A E 113 Vermiceras sp. PI . 5, F i g . 7; PI . 6, F i g . 4, 8 M A T E R I A L - More than 20 specimens preserved in shale or in concretions in shale, inner whorls often wi th considerable relief while outer whorls of larger specimens entirely flattened. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W C-156980/15 140 85 60.1 28 25 C-156980/13 90 44 48.9 21 27 C-156980/16 80 46 57.5 18.2 19 C-156980/14 51 22.5 43.5 16.3 22 C-156980/11 35 19 54.3 8 19 M e a n = Standard deviat ion= 52.86 6.69 D E S C R I P T I O N - Evolu te form of med ium size seldom exceeding 10 c m in diameter. W h o r l expansion rate and whor l overlap variable, but generally evolute and widely umbilicate. Inner whorl preserving considerable relief suggesting rounded umbi l i ca l wal l , convex flanks and probably inflated whorl section. In one unusual ly embedded specimen of m e d i u m size, the venter bearing a blunt keel flanked by shallow sulci can be seen (PI. 6, F i g . 4). Ornament consisting of dense, strong ribs of broad, rounded profile. Ribs straight, prorsiradiate on innermost whorls, soon becoming rectiradiate and loosing strength at adult stage. R i b b i n g frequency increasing steadily up to an umbi l i ca l diameter of approximately 30 m m , remaining nearly constant later (F ig . 6-7). SYSTEMATIC PALEONTOLOGY ARIETITINAE 114 PRHW 1 1" " - 1 1 — i — i — i — — , — n — i i i i i . . 0 20 40 60 80 100 U D ( m m ) Vermiceras sp.: n=24 y=0.21x+13.48 r=0.48 Figure 6-7 Rib frequency diagram of six specimens of Vermiceras sp. from the Canadensis Zone of Kennecott Point. DISCUSSION - This form resembles species of Vermiceras (Paracaloceras) known from the Alps (e.g. V. coregonense group) but differs from them by its characteristic ribbing style and density curve as shown on Fig. 6-7. OCCURRENCE - Kennecott Point, Section D, Levels 26-27; Section B, Levels 2 and 4; from the top of Canadensis Zone. GENUS Metophioceras SPATH, 1924 T Y P E SPECIES - Ammonites conybeari SOWERBY, 1816, by original designation. S Y S T E M A T I C P A L E O N T O L O G Y A RIE TITINA E 115 D E S C R I P T I O N - Serpenticone forms of med ium to large size. Venter tricarinate-bisulcate, costation dense. V e n t r a l rib ends may bear weak tubercles on inner whorls only. R E M A R K S - Metophioceras is used here in the sense of GUERIN-FRANIATTE (1966) that is for forms wi th strongly tricarinate-bisulcate venters similar to Coroniceras but without persistent tubercles. BLOOS (1989) pointed out the need for revision of genus as possibly containing species of heterogenous origin. A G E A N D D I S T R I B U T I O N - Metophioceras is most abundant in the Conybear i Subzone at the base of Sinemurian. It is best represented in Northwest Europe but also occurs in N o r t h A m e r i c a (see under M. rursicostatum). Metophioceras cf. rursicostatum (FREBOLD, 1967) PI . 7, Fig. 1 * v cf. 1967 Paracaloceras rursicostatum n . sp. - FREBOLD, 1967, p. 26, p i . 7, fig. 1-2; p i . 9, fig. 1 cf. 1981 Paracaloceras rursicostatum Frebold - IMLAY, p. 33, p i . 6, fig. 1-11 ? 1989 Vermiceras (Paracaloceras) cf. rursicostatum Freb . - RlCCARDI et al. , p i . 2, fig. 6 T Y P E - Holotype: FREBOLD, 1967, p i . 7, fig. 1 and p i . 9, fig. 1, G S C Type No . 19944. M A T E R I A L - 8 specimens preserved as highly compressed internal moulds in shale. S Y S T E M A T I C P A L E O N T O L O G Y A RIE TIT IN A E 116 M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W C-156953/1 136 84 61.8 27 25 C-156953/2 67 39 58.2 15.5 23 611L/2 60 35 58.3 13 22 D E S C R I P T I O N - Evolute form at taining large size (diameter of 30 cm). Whor l s enlarging slowly, umbil icus very wide up to more than 60%. Flanks appear to be sl ightly convex. Venter tricarinate-bisulcate at large size. Densely r ibbed throughout, rib frequency increasing slowly but steadily (F ig . 6-8). Ribs of moderately high and rounded profile, rursiradiate to various degree, gently concave adorally. D I S C U S S I O N - The costation of the species is variable and changes wi th ontogeny. The diagnostic rursiradiate r ibbing clearly seen on the holotype is less apparent on the paratype and at smaller sizes. Simi lar ly , the largest individuals in our collection are in good agreement w i t h the holotype whereas the more completely preserved smaller ones are closer to the paratype and also resemble similar sized specimens of V. ex gr. coregonense. SYSTEMATIC PALEONTOLOGY A RIE TIT IN A E 117 PRHW 20 --.L^C~ ^-— 1 1 — I I QCI s p e c i m e n s H o l o t y p e P a r a t y p e A 1 1 1 5 10 20 50 100 200 UD ( m m ) n=24 y=0.124x+17.17 r=0.79 Figure 6-8 Rib frequency curves of 5 specimens of Metophioceras cf. rursicostatum. from Kennecott Point plotted together with the holotype and paratype. OCCURRENCE - Kennecott Point, Sections D and F; from the Canadensis Zone. A G E AND DISTRIBUTION - At the type locality in Taseko Lakes area M. rursicostatum occurs in the Canadensis Zone (FREBOLD, 1967). In Alaska it also cooccurs with Badouxia canadensis (IMLAY, 1981). In Nevada the species ranges higher than B. canadensis (TAYLOR, 1990). The only record from outside North America is a possible occurrence from the Canadensis Zone of Argentina (RlCCARDI et al., 1989). S Y S T E M A T I C P A L E O N T O L O G Y A RIE TIT IN A E 118 Metophioceras aff. rotarium (BUCKMAN, 1925) PI. 6, Fig. 3, 6 aff. * 1925 Diploselhtes rotanus nov. - BUCKMAN, pi. 171 aff. 1966 Coroniceras (Metophioceras) rotarium (S. S. BUCKMAN, 1925) - GUERIN-FRANIATTE, p. 179, pi. 66-67, text-fig. 66-67 (with synonymy) M A T E R I A L - 8 specimens preserved as flattened one-sided internal moulds in shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W 607E/1 105.5 71.5 67.8 17.5 26 6 2 3 A / 1 >100 67.5 23 6 0 6 A / 1 38.5 21.5 56.8 9.0 18 C156980/31 38 22 58 8.7 18 D E S C R I P T I O N - High ly evolute form wi th m a x i m u m diameter exceeding 10 cm. W h o r l overlap less than 10%, umbil icus wide, whor l enlarging slowly. Traces of pronounced ventral keel flanked by sulci and possibly carinae seen despite flattened preservation. Densely ribbed, r ibb ing frequency increasing steadily. Number of ribs 20 to 25 at 50 m m umbi l ica l diameter (F ig . 6-9). Ribs strong, high, rectiradiate but concave adorally. V e n t r a l rib ends bearing weak tubercles on inner whorls only, later d iminishing to slightly swollen rib terminations. SYSTEMATIC PALEONTOLOGY A RIE TI TIN A E 119 PRHW 30 20 — 10 -0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 25 50 75 UD ( m m ) n=23 y=0.203x+11.61 r=0.B6 Figure 6-9 Rib frequency curves of 7 specimens of Metophioceras aff. rotanum from Kennecott Point plotted together with the holotype and another representative specimen of the species. DISCUSSION - The assignment of this form to Metophioceras is based on the weak tubercles developed on innermost whorls only. The closest comparison can be made with M. rotanum which is quite similar in ribbing but differs in having an even slower expansion rate therefore less high outer whorl and wider umbilicus. It differs from M. rursicostatum by having less rursiradiate and more concave ribbing. OCCURRENCE - Kennecott Point, Sections A, B, and D; from the upper part of the Canadensis Zone and "Coroniceras" Zone. S Y S T E M A T I C P A L E O N T O L O G Y A RIE TIT IN A E 120 D I S T R I B U T I O N - M. rotarium is known from the Conybear i Subzone (Buck land i Zone) of B r i t a i n and France. Metophioceras spp. PI . 7, F i g . 4 M A T E R I A L - Approx ima te ly 15 specimens, generally poorly preserved as flattened internal moulds in shale. D I S C U S S I O N - The specimens grouped under Metophioceras spp. display evolute shell, indicat ion of stout whorls, dense, upright r ibbing and traces of tricarinate-bisulcate venter. Their specific ident i ty could not have been established due to poor preservation. O C C U R R E N C E - Kennecot t Point , various levels in sections A , B , D , and F , from the upper part of the Canadensis Zone and "Coroniceras" Zone. G E N U S Coroniceras HYATT, 1867 T Y P E S P E C I E S - Ammonites Kridion ZlETEN, 1830, subsequent designation by BONARELLI (1900). A G E A N D D I S T R I B U T I O N - Coroniceras is a cosmopoli tan genus occuring in the B u c k l a n d i and Semicosta tum zones (Rotiforme through L y r a subzones). Coroniceras ? spp. P L 6, F i g . 7 M A T E R I A L - 14 poorly preserved specimens, most of them flattened impressions in shale. S Y S T E M A T I C P A L E O N T O L O G Y A RIE TIT IN A E 121 D I S C U S S I O N - Included here are evolute forms of various size wi th relatively rapidly enlarging whorls and strong, dense r ibbing. The expansion rate is higher than in Metophioceras or Vermiceras. The ventro-lateral row of tubercles typical of Coroniceras is only vaguely seen on some less weathered specimens. O C C U R R E N C E - Kennecott Po in t , Section B ; K u n g a Island, Section T , Levels 2-9, from the "Coroniceras" Zone. Ar ie t i t inae gen. et sp. indet. PI . 7, F i g . 6 M A T E R I A L - 6 flattened whor l fragments of very large size preserved in shale and siltstone. M E A S U R E M E N T S - Specimen N o . 6 0 7 B / 1 W H 97; Specimen No. 611E/16 W H 77 D E S C R I P T I O N - Fragments no more than VlO of a whorl . W h o r l height approaching 10 cm, curvature suggesting giant diameter in the order of approximately 80 cm. Venter strongly tricarinate-bisulcate. Costa t ion moderately dense, somewhat irregular, some ribs apparently bifurcating at origin at umbi l ica l end. Ribs blunt , low, adorally s l ight ly concave, fading out before reaching ventral carina. D I S C U S S I O N - The whorl fragments, as their giant size and irregular r ibbing suggest, belong to mature or senile individuals . In the lack of corresponding inner whorls no generic identification can be made. O C C U R R E N C E - Kennecott Po in t , Sections B , D , and F ; from the upper part of the Canadensis Zone and "Coroniceras" Zone. S Y S T E M A T I C P A L E O N T O L O G Y A RIE TI TINA E 122 G E N U S Arnioceras HYATT, 1867 T Y P E S P E C I E S - Arnioceras cuneiforme HYATT, 1867, by subsequent designation (ARKELL, 1951, p. 217, I C Z N Op in ion 307). S Y N O N Y M Y - Arnioceras SPATH, 1919 nomen nullum; Arniotites WHITEAVES 1889; Burckhardticeras LOPEZ, 1967; Eparnioceras SPATH, 1924. D E S C R I P T I O N - Evolute forms wi th wide umbil icus representing about 45-60% of diameter. W h o r l section subrectangular to oval . Venter bearing a sharp keel flanked by sulci in most cases; some forms possess tricarinate venter. Innermost whorls diagnostically smooth up to various diameters. After the smooth stage simple r ibbing develops consisting of gently prorsiradiate to gently rursiradiate, sharp, acute, most often straight ribs. Ribs may be projected forward before their ventral terminat ion which sometimes accentuated. Sutures relatively simple characterized by deeply incised lateral lobes. R E M A R K S - Arnioceras as a genus is easy to identify whereas the recognition of species is a difficult task. The plethora of nominal species (their number exceeds 50) often display only minor differences. F r o m a single locality in Italy FUCINI (1902) distinguished 29 species, 18 of which were new, and numerous subspecies. The narrow species concept employed by h i m has been a t radi t ion concerning Arnioceras: Diagnostic features used to separate species include the umbi l ica l ratio ( U ) , umbi l ica l diameter at which ribs appear, trend of ribs, rib density pattern, and ventral terminat ion of ribs. Since the flattened preservation of the Queen Char lot te material precludes the observation of important features such as the whor l section and venter, the use of ex gr. nomenclatural category is sometimes necessary. A G E A N D D I S T R I B U T I O N - Arnioceras is a cosmopolitan genus wi th a relatively long range. It is known from pract ical ly every region where ammonitiferous Lower Sinemurian is exposed. In Europe it is diverse and S Y S T E M A T I C P A L E O N T O L O G Y A RIE TIT IN A E 123 abundant in both provinces. It is also well known from the Circum-Pacific (see SATO, 1957 and 1975 for west and southwest Pacific, RlCCARDI et al., 1990 for South American, FREBOLD and TIPPER, 1970 for Canadian, IMLAY, 1981 for Alaskan, HALLAM, 1965 for other western North American occurrences). Arnioceras appeared near the end of the Bucklandi Zone and ranged through the Obtusum Zone (DEAN et al., 1961, MOUTERDE et al., 1971), however, it is most characteristic to the Semicostatum Zone. The succession of the species has been the subject of relatively few studies (e. g. SPATH, 1956; BLIND, 1963, CASSINIS and CANTALUPPI, 1967, BRAGA et a l , 1984b) possibly due to the problems of interpretation of some closely related and narrowly defined species. Arnioceras arnouldi (DUMORTIER, 1867) PI. 8, Fig. 3; PI. 9, Fig. 1-2 1867 Ammonites arnouldi Nov. Sp. - DUMORTIER, p. 27, pi. 5, fig. 1-2; pi. 6, fig. 1-6 1869 Ammonites nevadanus, Gabb - GABB, p. 6, pi. 3, fig. 1 1878 Arietites Douvillei BAYLE - BAYLE, pi. 76, fig. 2-3 1902 Arnioceras Arnouldi DUM. - FUCINI, p. 193, pi. 25, fig. 1-2 (non fig. 3 = Arnioceras densicosta) 1928 Arnioceras kwakiutlanus sp. nov. - CRICKMAY, p. 1956 Arnioceras arnouldi (DUM.) - ERBEN, p. 272, pi. 32, fig. 1 1966 Arnioceras arnouldi (DUMORTIER, 1867) - GUERIN-FRANIATTE, p. 279, pi. 150-152 1967 Arnioceras arnouldi (DUM.) - CANTALUPPI, p. 60, pi. 7, fig. 2-3 1979 Arnioceras cf. arnouldi (DUM.) - GEYER, p. 208, fig. 5d ( = Epophioceras sp.) 1981 Arnioceras arnouldi (DUMORTIER, 1867) - SMITH, p. 135, pi. 1, fig. 3-5, text-fig. 6-2 T Y P E - Lectotype: "Ammonites Arnouldi" of DUMORTIER, 1867, pi. 6, fig. 1-4, designated and refigured by GUERIN-FRANIATTE, 1966, p. 279, pi. 150; deposited in the Natural History Museum of Lyon. pars ? M A T E R I A L - 15 specimens, 2 of them almost complete compressed internal moulds, 1 three-dimensional whorl fragment, 1 almost complete impression, while the others are incomplete and poorly preserved impressions. SYSTEMATIC PALEONTOLOGY A RIE TI TIN A E 124 PRWH 40 -. 0 ' 1 1 1 1 1 1 1 1 1 1 1 1 0 50 100 150 UD ( m m ) n=27 y=0.172x+15.19 r=0.78 Figure 6-10 Rib density curves of Arnioceras arnouldi. MEASUREMENTS SPECIMEN NO. DMAX UD U WH PRHW 717A/1 %225 153 %68 38 40 708C/1 ssl25 «87 %69 26 «30 ST90-06/1 ssllO 70 64 28 27 DESCRIPTION - Evolute form attaining large size. Whorl section subrectangular, venter bearing a sharp, high keel flanked by well-developed sulci. Umbilicus represents 60-70% of diameter. Nucleus smooth up to an umbilical diameter of 5-9 mm from which point dense ribbing develops. Ribs sharp and high, rectiradiate and straight on juvenile becoming rursiradiate and concave adorally on adults, projected forward at the ventro-lateral shoulder. Rib density increases throughout ontogeny (Fig. 6-10). S Y S T E M A T I C P A L E O N T O L O G Y A RIE TIT IN A E 125 D I S C U S S I O N - Arnioceras arnouldi is probably the largest species wi th the widest umbil icus among the representatives of the genus. The rib density of some of our individuals exceed the upper l imi t of rib density range determined by GUERIN-FRANIATTE (1966, fig. 142).A. speciosum, which can also at ta in large size, can be dist inguished by its straight rectiradiate r ibbing not showing a tendency to become arcuate and rursiradiate wi th matur i ty . GABB's (1867) A. nevadanus is tentatively synonymized wi th A. arnouldi. Arniotites kwakiutlanus CRICKMAY, 1928 is based on rather incomplete and poorly preserved type material and is uninterpretable. It is most l ikely to represent fragments of A. arnouldi al though it cannot be stated decisively an the name should be allowed to fall into disuse. O C C U R R E N C E - Y a k o u n River , Section H; T a s u Sound, Section Q; K u n g a Island, Section S and T ; from the A r n o u l d i and Var ians Zones. A G E A N D D I S T R I B U T I O N - A. arnouldi is known in Europe from the upper B u c k l a n d i through O b t u s u m zones (CASSINIS and CANTALUPPI, 1967). The species has also been recorded from Mexico (ERBEN, 1956) and Nevada (SMITH, 1981) from the " U n i t w i th Arnioceras geometncoides" and A. ceratitoides Zone, respectively. Arnioceras miserabile (QUENSTEDT, 1858) PI . 7, F i g . 2 1858 Ammonites miserabilis - QUENSTEDT, p. 71, p i . 8, fig. 7 1879 Ammonites geometricus var. Hartmanni OPPEL - REYNES, p i . 15, fig. 3-4 1884 Ammonites miserabilis - QUENSTEDT, p. 106, p i . 13, fig. 27-29 1886 Arietites ambiguus nov. sp. - GEYER, p. 252, p i . 3, fig. 11-12 1889 Arnioceras miserabilis var. acutidorsale - HYATT, p. 162, p i . 2, fig. 4-6 1902 Arnioceras miserabile QU. - FUCINI, p. 162, p i . 16, fig. 10 1955 Arnioceras miserabile (QU.) - DONOVAN, p. 28 1956 Arnioceras cf. miserabile (QU.) - ERBEN, p. 273, p i . 37, fig. 18 1966 Arnioceras miserabile (QUENSTEDT, 1858) - GUERIN-FRANIATTE, p. 254, p i . 136, fig. 1-4 1973 Arnioceras cf. miserabile (QU.) - GEYER, p. 52, p i . 4, fig. 6 1976 Arnioceras miserabile (QU.) - SCHLEGELMILCH, p. 49, p i . 21, fig. fig. 5 S Y S T E M A T I C P A L E O N T O L O G Y A RIE TIT IN A E 126 pars 1981 Arnioceras miserabile (QUENSTEDT, 1858) - SMITH, p. 143, p i . 2, fig. 2 (non fig. 3 -Hypasteroceras? sp. 1985 Arnioceras cf. miserabile (QUENSTEDT, 1858) - PRINZ, p. 179, p i . 3, fig. 6 1987 Arnioceras cf. miserabile (QUENSTEDT) - QUINZIO SINN, p i . 3, fig. 2 T Y P E - Neotype: "Ammonites miserabilis" of QUENSTEDT, 1884, p i . 13, fig. 27, designated and refigured by GUERIN-FRANIATTE, 1966, p. 254, p i . 136, fig. 1. M A T E R I A L - Three specimens preserved as impressions in shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H 2 A / 1 34.3 18.7 54.5 8.7 705P/3 20.8 9.9 47.6 5.2 D E S C R I P T I O N - Evolute form wi th wide umbil icus and slowly enlarging whorls. The smaller ind iv idua l entirely smooth, on the larger one faint, gently arcuate incipient ribs appear only at an umbi l ica l diameter of 18 m m . D I S C U S S I O N - A. miserabile can be readily dist inguished from other species of Arnioceras by its smooth shell displaying only faint lirae or incipient r ibb ing from an umbi l i ca l diameter over 1 cm. Therefore it can be safely identified on our two-dimensionally preserved material , even though the diagnostic ovate-ogival whorl section and poorly developed or lacking keel cannot be observed. O C C U R R E N C E - Y a k o u n River , Section H , Level 12; K u n g a Island, Section T ; Level 14; from the A r n o u l d i Zone. S Y S T E M A T I C P A L E O N T O L O G Y A RIE TI TIN A E 127 D I S T R I B U T I O N - In Europe A. miserabile occurs in both the northwest European and Mediterranean provinces. It has also been reported from several localities in South A m e r i c a (Colombia , Pe ru , Chile)(RJCCARDI et al, 1990) as well as Nor th A m e r i c a (Nevada: SMITH, 1981, Mexico : ERBEN, 1956). Where detailed stratigraphic information is available it suggests Semicostatum Zone age. Arnioceras cf. densicosta (QUENSTEDT, 1884) PI. 7, Fig. 3 cf. 1879 Ammonites geometricus OPPEL - REYNES, p i . 14, fig. 5-6 *cf. 1884 Ammonites falcaries densicosta - QUENSTEDT, p. 100, p i . 13, fig. 7 cf. 1902 Arnioceras pluriplicatum n . sp. - FUCINI, p. 155, p i . 25, fig. 4-5 1955 Arnioceras cf. densicosta (QUENSTEDT) - DONOVAN, p. 27 1966 Arnioceras cf. densicosta (QUENSTEDT, 1884) - GUERIN-FRANIATTE, p. 265, p i . 142, fig. 1-3, text-fig. 130-131 1981 Arnioceras cf. A. densicosta (QUENSTEDT) - IMLAY, p. 33, p i . 5, fig. 9-11, 16-24 cf. 1985 Arnioceras pluriplicatum FUCINI - BRAGA et a l , p. 96, p i . 1, fig. 3 1987 Arnioceras cf. densicosta (QUENSTEDT) - QUINZIO SINN, p i . 2, fig. 14 T Y P E - Lectotype: "Ammonites falcaries densicosta" of QUENSTEDT, 1884, p i . 13, fig. 7, designated and refigured by GUERIN-FRANIATTE, 1966, p. 265, p i . 142, fig. 1; deposited in the Quenstedt collection of the Geological Institute, Tub ingen . M A T E R I A L - One flattened internal and external mould preserved in shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W K 6 E / 1 42.8 21.2 49.5 11.0 25 D E S C R I P T I O N - Evolu te form wi th wide umbil icus and moderately enlarging whorls. Smooth up to an umbi l i ca l diameter of 7 m m , where dense, radial r ibbing develops. Later ribs tend to become gently S Y S T E M A T I C P A L E O N T O L O G Y A RIE TITINA E 128 rursiradiate. R i b b i n g density increases only sl ightly w i t h growth. R ibs reach the ventro-lateral shoulder apparently without being projected forward. D I S C U S S I O N - Our specimen is in good agreement wi th the lectotype of Arnioceras densicosta and FUCINI's A. pluriphcata, wi th which it is synonymyzed herein. BRAGA et al . (1985) states the presence of sulci as the distinctive difference between A. plunplicata and A. densicosta but sulci are clearly present on A. densicosta (GUERIN-FRANIATTE, 1966). The dense r ibb ing pat tern makes this species readily distinguishable from other species of Arnioceras. O C C U R R E N C E - K u n g a Island, Section T , Level 22; from the A r n o u l d i Zone. D I S T R I B U T I O N - A. densicosta is known from the Semicosta tum Zone of southern Germany, France (GUERIN-FRANIATTE, 1966), Spain (BRAGA et al., 1985) and Chi le (QUINZIO SINN, 1987) as well as from the Lower Sinemurian of Italy (FUCINI, 1902) and A l a s k a (IMLAY, 1981). Arnioceras cf. oppeli GUERIN-FRANIATTE, 1966 PI. 8, Fig. 1 *cf. 1966 Arnioceras oppeli n . sp. - GUERIN-FRANIATTE, p. 267, p i . 143, fig. 1-3, text-fig. 132-134 (with synonymy) ? 1968 Arnioceras cf. oppeli GUERIN - FEDERICI, p. 122, fig 4e-f cf. 1976 Arnioceras oppeli GUERIN-FRANIATTE - SCHLEGELMILCH, p. 48, p i . 20, fig. 5 cf. 1981 Arnioceras cf. oppeli GUERIN-FRANIATTE, 1966 - SMITH, p. 145, p i . 2, fig. 1, 4 ? 1987 Arnioceras cf. oppeli GUERIN-FRANIATTE - QUINZIO SINN, p i . 2, fig. 13 T Y P E - Holotype: "Arnioceras geometricum OPPEL" figured by JAWORSKI, 1931, p i . 2, fig. 2, original designation by GUERIN-FRANIATTE, 1966, p. 267; refigured therein, p i . 143, fig. 1; deposited in the Bavar ian State M u s e u m of Geology and Paleontology, M u n i c h . S Y S T E M A T I C P A L E O N T O L O G Y A RIE TIT IN A E 129 M A T E R I A L - 5 more or less fragmentary flattened external moulds preserved in shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W K 8 J / 1 83.4 43.8 52.4 ~24 K 9 I / 1 68.5 34.1 49.8 ~19.5 18 D E S C R I P T I O N - M e d i u m size, evolute form wi th moderately wide umbil icus representing about Vb of diameter. Venter bearing a keel. Smooth up to an umbi l ica l diameter of 5-7 m m , from which point sparse costation develops increasing in frequency wi th grolwth. Ribs sharp, straight, rectiradiate both on umbi l ica l wall and flanks, terminat ing abrupt ly at ventro-lateral shoulder, rib ends accentuated. D I S C U S S I O N - The nomenclature as well as the morphology of the species is discussed in detail by GUERIN-FRANIATTE (1966). O u r material is in good agreement wi th A. oppeli in terms of rib frequency, r ibb ing style, and umbi l ica l ratio. O C C U R R E N C E - K u n g a Island, Section S and T ; from the A r n o u l d i and Var ians Zones. D I S T R I B U T I O N - A. oppeli is abundant in the Semicostatum Zone of various localities in northwest Europe (GUERIN-FRANIATTE, 1966). It is also known from the Medi terranean province, e. g. the Semicosta tum Zone of the Bet ic Cordi l lera , Spain (BRAGA et a l , 1984), B u c k l a n d i and Semicosta tum zones of Italy (FEDERICI, 1968). A. aff. oppeli is recorded from the O b t u s u m Zone of Hungary (GECZY, 1972). In Nor th A m e r i c a SMITH (1981) found A. cf. oppeli in his A . ceratitoides Zone. In South A m e r i c a the Semicostatum Zone of northern Chi le yielded the species (QUINZIO SINN, 1987). S Y S T E M A T I C P A L E O N T O L O G Y A RIE TIT IN A E 130 Arnioceras cf. speciosum FUCINI, 1902 PI. 9, Fig. 3, 6 * cf. 1902 Arnioceras speciosum n. sp. - FUCINI, p. 184, pi. 20, fig. 1-8; pi. 21, fig. 1-4 M A T E R I A L - 2 external and 2 internal moulds, incomplete and flattened, preserved in shale and siltstone. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R W H 7061/1 145.5 81.5 56 37 31 706P/1 ~109 60.2 55.2 ~29 S T 90-06 82 45 54.9 22 D E S C R I P T I O N - Evolute , med ium to large size form. Venter tricarinate-bisulcate. Dense and sharp costation sets on at an umbi l ica l diameter of about 6 m m . R i b frequency increases steadily throughout ontogeny (F ig . 6-11). Ribs somewhat rursiradiate on umbi l ica l wal l , straight and rectiradiate on flanks and swing forward at the ventro-lateral shoulder to merge the lateral carina. SYSTEMATIC PALEONTOLOGY A RIE TJTINA E 131 PRHW 3 0 -2 0 10 -0 QOI s p e c i m e n s F u c i n i 1 9 0 2 , p l . 2 0 , f i g . 1 F u c i n i 1 9 0 2 , p l . 2 0 , f i g o-~i 1 r -i 1 r - i 1 r 0 2 0 4 0 U D ( m m ) 6 0 8 0 Figure 6-11 Rib frequency curves of Arnioceras speciosum. DISCUSSION - According to BRAGA et al. (1985) this species is closely related to A. mendax, the only distinction between them being the sparser ribbing on the inner whorls of A. speciosum. In our opinion the difference is stronger when one compares the ribbing density curves, where A. mendax shows much slower rate of rib frequency increase. The differences between A. speciosum and A. arnouldi are discussed under A. arnouldi. A. speciosum also differs from the A. ceratitoides group by its more pronounced projection of ribs. OCCURRENCE - Tasu Sound, Section R, Kunga Island, Sections S and T; from the Arnouldi and Varians Zones. S Y S T E M A T I C P A L E O N T O L O G Y ARIETITINAE 132 A G E A N D D I S T R I B U T I O N - A. speciosum has only been recorded from Italy (FUCINI, 1902), where its s trat igraphic position is not well constrained, and from the O b t u s u m Zone of Hungary ( G E C Z Y , 1972). Arnioceras ex gr. ceratitoides Q U E N S T E D T , 1849) PI . 10, F i g . 1-2 M A T E R I A L - 15 specimens preserved mostly as flattened internal and external moulds in shale and silststone. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W Y L 8/3 110.6 58.5 52.9 22 Y L 1 1 / 7 97.7 51 52.2 26.6 Y L 7 / 1 1 = 1 5 71.8 36.4 50.7 17.9 22 Y L 8 / 1 57.1 25.4 44.5 18 15 K 8 U / 1 ~52 ~23 44.2 ~15 17 D E S C R I P T I O N - Evolute form of m e d i u m size, whorls enlarging moderately rapidly for genus. Umbi l i cus usually less than V2 of diameter, umbi l i ca l ratio increasing w i t h growth. Venter bearing a high keel. Smooth up to an umbi l ica l diameter of 5-10 m m , later densely r ibbed. R ibs sharp, rectiradiate showing a tendency of becoming gently rursiradiate at matur i ty . Ribs sl ightly projected forward at the ventro-lateral shoulder. D I S C U S S I O N - FUCINI (1902) i l lustrated a large number of specimen of A. ceratitoides and set up a subspecies to accomodate a more sparsely r ibbed forms. The diagnostic characteristics of the species include the umbi l icus rather narrow for genus, a tendency of ribs to become rursiradiate, and a slow increase in rib frequency. Other , more narrowly interpreted species, such as A. rejectum FUCINI, 1902 and A. italicum FUCINI , 1902 may differ from A. ceratitoides in whorl section and ventral features only. Even if these S Y S T E M A T I C P A L E O N T O L O G Y A RIE TIT IN A E 133 differences were beyond intraspecific variat ion, they do not allow dis t inct ion i n badly preserved material , therefore here they are included in A. ex gr. ceratitoides. Arniotites begbiei CRICKMAY, 1928 is based on poorly preserved fragmentary type material from Harbledown Island. It is considered uninterpretable and should be allowed to fall in to disuse. The rather high whorls and straight ribs may suggest affinity to the A. ceratitoides group. O C C U R R E N C E - Y a k o u n River , Section H , K u n g a Island, Section S and T ; from the A r n o u l d i and Var ians Zones. D I S T R I B U T I O N - A. ceratitoides s. str. is frequently cited from the Semicosta tum Zone of northwest Europe. BLIND (1963) recorded a longer range inc luding the O b t u s u m Zone. In the Medi terranean province BRAGA et al. (1984) reported the species from the Semicostatum Zone of the Bet ic Cord i l l e ra of Spain, while in Italy FERRETTI (1975) found it together wi th Paroxynoticeras indicat ing a higher ( O x y n o t u m Zone?) level, although this identification was questioned by DONOVAN (1990). The species is widely distr ibuted outside Europe as well. It is possibly present in the western Pacific ( R O T H P L E T Z , 1882, S A T O , 1967). South A m e r i c a n occurrences include Co lombia , Ecuador , Peru , Chi le and are confined to the middle part of the Lower Sinemurian (RlCCARDI et al. , 1990). It was also found in Mexico (ERBEN, 1956), Nevada (Arnioceras humboldti of HYATT, 1869; SMITH, 1981), and Oregon (SMITH, 1981). References to A. rejectum and A. italicum are less numerous in the li terature, their stratigraphic and geographic range are narrower than that of A. ceratitoides. Arnioceras ex gr. mendax FUCINI, 1902 PI. 8, Fig. 2 M A T E R I A L - 2 external and 2 internal moulds, preserved extremely flattened in shale. S Y S T E M A T I C P A L E O N T O L O G Y A RIE TIT IN A E 134 M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R W H Y L 7/3 70.1 39.8 56.8 17.8 _ 706H/1 61 35.9 58.8 19 K 6 J / 1 ~86 53 61.6 23 K 6 L / 9 41.5 22.0 53.5 12.3 19 D E S C R I P T I O N - Shel l of m e d i u m size, diameter ranges between 5-10 cm. Evolute form, umbil icus represents 55-60% of diameter. Venter bearing prominent keel, further details obscured by two-dimensional preservation. Nucleus smooth up to an umbi l ica l diameter of 7 m m on the only specimen preserved wi th inner whorls. Ribs straight, rectiradiate and dense on inner whorls wi th rib frequency remaining constant or increasing only slowly. V e n t r a l terminat ion of ribs without projection or geniculation. D I S C U S S I O N - In our rather poorly preserved material A. mendax cannot be separated from A. dimorphum, a closely related form (in fact, their separate ident i ty is questionable even wi th well-preserved specimens). A comprehensive discussion of A. mendax inc luding its subspecies is given by GUERIN-PRANIATTE (1966). A n extremely short smooth stage indicated on her text-fig. 135 is not evident from FUCINI's (1902) figured specimens therefore cannot substantiate a dist inct ion between A. mendax and A. dimorphum. In FUCINI's monograph, A. mendax is amongst the most loosely interpreted species. O n the other hand A. dtmorphum has much narrower var iabi l ty falling wi th in the range of A. mendax. The straight, rectiradiate r ibbing without a ventral projection of the rib, together wi th the l i t t le , if any, increase in rib frequency serve as a basis of differentiation from the A. ceratitoides group, which tends to have rursiradiate r ibb ing in matur i ty ; A. oppeli, which shows a higher rate of rib frequency increase; and A. arnouldi, which also possess projected ventral rib terminations. O C C U R R E N C E - Y a k o u n River , Section H , K u n g a Island, Section T ; from the A r n o u l d i Zone. S Y S T E M A T I C P A L E O N T O L O G Y A RIE TI TIN A E 135 A G E A N D D I S T R I B U T I O N - A. mendax was originally described from the Sinemurian of Monte di Cetona, Italy (FUCINI, 1902). A summary of the other Italian occurrences is given by FEDERICI (1968) who assigned Buck land i /Semicos ta tum Zone age to them. GUERIN-FRANIATTE (1966) reports it from the Semicostatum Zone of France. The species was also recorded from the O b t u s u m and O x y n o t u m zones of Hungary, the latter is unusually high for the genus (GECZY, 1972). BRAGA et al . (1984) found the species in the basal part of the Semicostatum Zone of the Bet ic Cordi l lera , Spain . A. dimorphum was also found in both the Lower and Upper Sinemurian of Italy (FEDERICI, 1968). BRAGA et al. (1984) recorded it from the O b t u s u m Zone of Spain. The only occurrence in. northwest Europe was questionably reported by SPATH (1956) from the Semicostatum Zone of Eng land . Arnioceras sp. PI . 7, F i g . 5 M A T E R I A L - 3 small but complete specimens preserved as flattened impressions in shale and an addi t ional 18 fragments of specimens of various sizes wi th similar preservation. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W R 622B/1 28.0 14.5 51.8 7.8 17 6.3 15 622B/2 24 11.5 48 6.5 17 D E S C R I P T I O N - Shell of med ium size, evolute, umbil icus represents about V2 of diameter at juvenile stage, umbi l i ca l rat io increases wi th growth. Venter tricarinate-bisulcate as far as preservation allows observation. Nucleus smooth up to an umbi l ica l diameter of 4 m m . R i b b i n g dense, frequency increases steadily wi th growth based on fragments of different diameter. Ribs sharp, s l ight ly prorsiradiate on juvenile specimens to S Y S T E M A T I C P A L E O N T O L O G Y A RIE TITINA E 136 sl ightly rursiradiate on larger fragments, curved gently forward on upper flank before merging into lateral carina. D I S C U S S I O N - The lack of better preserved individuals precludes a full description and identification. Th i s form seems to be the earliest representative of the genus in the Queen Charlot te Islands. O C C U R R E N C E - Kennecot t Po in t , Section B ; from the base of "Coroniceras" Zone. S U B F A M I L Y A S T E R O C E R A T I N A E S P A T H , 1946 G E N U S Asteroceras T Y P E S P E C I E S - Ammonites stellans S O W E R B Y , 1815 (p. 211, p i . 93) by subsequent designation (S. B U C K M A N , 1911, p. 5) ( I C Z N Op in ion 324). D E S C R I P T I O N - Midvo lu t e forms wi th relatively rapidly expanding, compressed whorls. W h o r l sides converging above mid flank, venter bearing prominent keel often, but not always accompanied by lateral sulci . Strongly r ibbed, ribs straight or sl ightly curved forward, radial or gently prorsiradiate. Sutures wi th broad, l i t t le incised saddles and shallow lobes. R E M A R K S - Asteroceras is a well-known genus consisting of numerous species. A l l species assigned to A. s. str. were first described from Europe, where northwest European and Mediterranean faunas contrast in their respective specific content. G U E R I N - F R A N I A T T E ' s (1966) comprehensive treatment is pr imar i ly concerned w i t h representatives of the genus from France mainly belonging to northwest European province (16 species described), whereas FUCINI ' s (1903) work discusses 9 species from Italy (Mediterranean province) - there are only two common species. Despite this significant diversity one can notice a disproportionate number of references to A. obtusum and A. stellare especially in less detailed paleontological studies from various parts S Y S T E M A T I C P A L E O N T O L O G Y ASTEROCERATINAE 137 of the world (for examples see synonymy lists below). A revision of these is needed for a more realistic picture of the paleobiogeography of the genus. A G E A N D D I S T R I B U T I O N - Asteroceras is a cosmopolitan genus confined to the O b t u s u m Zone except for some precursors in the T u r n e r i Zone. A s mentioned above it is abundant in both faunal provinces of Europe. Other occurrences include C h i n a , Japan, Nor th and South A m e r i c a . Asteroceras saltriense ? ( P A R O N A , 1896) PI. 10, F i g . 9 1903 Asteroceras saltriense P A R . - FUCINI, p. 186, p i . 33, fig. 4-6 cf. 1951 Asteroceras cf. stellare Sowerby - F R E B O L D , p. 11, p i . 13, fig. 2 cf. 1985 Asteroceras cf. suevicum ( Q U E N S T E D T ) - B R A G A et al . , p. 97, p i . 1, fig. 5 1988 Asteroceras cf. suevicum ( Q U E N S T E D T ) - M c F A R L A N E , p. 42, p i . 2, fig. 4-6 1990 Asteroceras mendionalis nov. sp. - D O M M E R G U E S et al . , p. 317, p i . 2, fig. 2-9; p i . 3, fig. 1 M A T E R I A L - Five specimens of poor to mediocre preservation as internal moulds in shale or siltstone flattened to various degrees; and two specimens w i t h three-dimensional but one-sided preservation in sandstone. M E A S U R E M E N T S S P E C I M E N N O . D M A X D U D U W H P R H W 706S/1 <93 <30.5 32.6 <37.8 16 >68.3 >22.5 32.9 >29.8 15 M I / 1 74.7 20.2 27.0 30.7 15 54.7 14.5 26.5 17.4 14 708S/1 50.5 16.0 31.7 19.1 14 Y L 1 1 / 4 42.0 13.2 31.4 17.8 13 28C1/1 « 4 8 17.0 %35 %20 15 D E S C R I P T I O N - M e d i u m size w i t h diameter of 5-10 cm. Rather involute for genus wi th a whorl overlap of 30-50%. Whor l s enlarging moderately, umbil icus m e d i u m wide. U m b i l i c a l wal l vert ical wi th rounded S Y S T E M A T I C P A L E O N T O L O G Y ASTEROCERATINAE 138 umbi l i ca l shoulder. F lanks only slightly convex. Venter not clearly seen, some indicat ion of a blunt keel. S t rong and moderately dense r ibbing wi th about 15 ribs per half whor l on adults. Ribs straight, radia l or gently prorsiradiate, s tar t ing on umbi l ica l wall , somewhat broadening ventral ly and terminat ing at the ventro-lateral shoulder. Profile of ribs rounded triangular, interspace wider than rib bases. D I S C U S S I O N - Our material agrees satisfactorily wi th the specimens of A. saltriense figured from various Medi ter ranean localities. Some specimens of FUCINI's A. varians (1903, e. g. p i . 32, fig. 1) also show resemblance in involut ion and r ibbing density, however, others show ribs fading out on the flanks. A. meridionalis is synonymized wi th A. saltriense herein as there does not appear to be sufficient ground for separation based on the abundant i l lustrat ion given in DOMMERGUES et a l , 1990. In fact these authors emphasized the great s imi lar i ty to "A. cf. suevicum" of BRAGA et al . (1985) just i fying the separation purely by differing r ibbing density. A comparison of figures, however, reveals nearly ident ical rib frequency, well w i th in intraspecific var ia t ion. The remaining problem in need of resolution concerns the remarkable s imi lar i ty of A. saltriense and A. suevicum as already pointed out by BRAGA et al. (1985, p. 97). These authors synonymized the two forms, of which A. suevicum has pr ior i ty , arguing for no substantial morphological difference. Thei r separate specific ident i ty is provisionally retained here, however, based on the much larger size (characteristically 10-20 cm) and narrower umbil icus at younger stage of A. suevicum. A succinct summary of differences between A. suevicum and A. obtusum as well as A. stellare is given by GUERIN-FRANIATTE (1966) and is equally applicable to A. saltriense. O C C U R R E N C E - Y a k o u n River , Section H , Level 13, Section I, Level 1; M a u d e Island, Section M , Level 3; K u n g a Island, Section S, Level 28, Section T , Level 36 ; from the Var ians Zone. D I S T R I B U T I O N - In Southern Europe (Betic Cordillera: BRAGA et al. (1985), Lombardian Alps: PARONA (1896), Central Appenmes: FUCINI (1903), S wiss Prealps: DOMMERGUES et al. (1990)), in North America S Y S T E M A T I C P A L E O N T O L O G Y ASTEROCERATINAE 139 beside the Queen Char lot te Islands possibly from Tyaugh ton Creek area (FREBOLD, 1951). A l l stratigraphic evidence suggest O b t u s u m Zone age. Asteroceras cf. varians FUCINI, 1903 PI. 10, Fig. 4, 6 * cf. 1903 Asteroceras varians n . sp. - FUCINI, p. 194, p i . 31, fig. 1-8; p i . 32, fig. 1-3 1988 Arctoasteroceras jeletzkyi FREBOLD, 1960 - McFARLANE, p. 48, p i . 1, fig. 7; p i . 2, fig. 1-2 pars 1988 Asteroceras cf. obtusum (SOWERBY, 1817) - McFARLANE, p. 39, p i . 1, fig. 1-4 (non p i . 2, fig. 3 = Asteroceras aff. margarita) cf. " 1988 Asteroceras aff. varians FUCINI - CECCA et al. , p. 70, p i . 1, fig. la-b , 7-8 M A T E R I A L - E igh t specimens of which six are flattened internal moulds in shale and siltstone and two are three-dimensional but one-sided external moulds preserved in sandstone. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W Y L 1 1 64.8 22.2 34.3 26.4 13 Y L 1 0 6 / 1 49.3 14.8 30.0 19.7 11 D E S C R I P T I O N - Smal l to m e d i u m size m i d volute form. Umbi l i cus narrow for genus, whorls enlarging moderately. U m b i l i c a l wal l low but steep, umbi l i ca l shoulder rounded. F lanks slightly convex. Venter is not preserved. R i b b i n g commonly not dense, varies extensively in strength. Ribs straight, radial , originating on umbi l ica l wal l , th ickening on middle flank than fading out on upper flank. Interspaces between ribs wider than rib bases. D I S C U S S I O N - A s the name suggests, the species shows significant var iabi l i ty , par t icular ly in r ibbing strength (FUCINI, 1903, p. 195). FUCINI himself distinguished four subspecies to accommodate the differences. The identification of the present form wi th any of these subspecies has not been attempted. S Y S T E M A T I C P A L E O N T O L O G Y ASTEROCERA TINAE 140 Ar do aster o ctr as jeletzkyi FREBOLD, 1960 is a species described from the Northwest Terri tories. It is similar to our form in volut ion and the fading of the ribs on the upper flanks. The pr imary morphological difference, the presence of a keel on A. varians versus the smooth venter of Arctoasteroceras jeletzkyi, cannot be proved in the present material . A. jeletzkyi, however, occurs in higher parts of the Upper Sinemurian together wi th Oxynoticeras according to FREBOLD, while IMLAY (1981) reported occurrences together w i t h Paltechioceras. Thus there may be sufficient stratigraphic ground for the dis t inct ion of these species even i n poorly preserved material . O C C U R R E N C E - Y a k o u n River , Section H , Level 13, Section I, Levels 2, 3, 6; K u n g a Island, Section S, Level 36; from the Var ians Zone. D I S T R I B U T I O N - A. varians has only been known from the Appenines , where CECCA et al . established Lower Lothar ingian age (i. e. O b t u s u m Zone equivalent) for i t . DONOVAN (1990) suggests a Late O b t u s u m Zone age (Denotatus Subzone) based on morphological similarities to Eparietites. Asteroceras aff. margarita (PARONA, 1896) PI . 10, Fig. 5 *aff. 1896 Arietites (Asteroceras) margarita sp. nov. - PARONA, p. 41, p i . 5, f ig. 8 (refigured in GUERIN-FRANIATTE, 1966, p i . 159) aff. pars 1903 Asteroceras margarita PAR. - FUCINI, p. 187, p i . 32, f ig. 4 (non f ig. 5 = Asteroceras saltriense) aff. 1966 Asteroceras margarita (PARONA, 1896) - GUERIN-FRANIATTE, p. 287, p i . 159-162 ? 1981 Asteroceras (Eparietites) n . sp. - SMITH, p. 151, p i . 2, f ig. 6, 8 pars 1988 Asteroceras cf. obtusum (SOWERBY) - McFARLANE, p. 39, p i . 2, fig. 3 (non p i . 1, f ig. 1-4 = Asteroceras cf. varians) T Y P E - Holotype: S toppani collection, Museo civico de M i l a n , figured by PARONA, 1896, p. 41, p i . 5, fig. 8, refigured by GUERIN-FRANIATTE, 1966, p i . 159 S Y S T E M A T I C P A L E O N T O L O G Y ASTEROCERA TINAE 141 M A T E R I A L - Seven poorly preserved fragmentary flattened internal moulds in siltsone and shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X D U D U W H P R H W 708P/2 >120 61 s=48 %41 20 29.5 15 Y L 1 0 5 / 2 92.7 39.2 42.3 %37 %17 70.5 25.5 36.2 %20 16 709E/1 %82 38.5 %47 23.2 « 1 7 17.0 12 709P /1 %72 %30 %42 %27 %15 Y L 1 1 / 3 37.0 16.3 44.0 12.0 15 D E S C R I P T I O N - Evolute form at ta ining m e d i u m to large size (largest measured D>120 mm) . The poor preservation obscures three-dimensional details such as whorl section, venter, umbi l ica l wal l . Coarsely ribbed, ribs gently prorsiradiate on umbi l ica l wal l , then incl ined to become gently prorsiradiate from lower flank cont inuing almost straight up to the ventro-lateral shoulder. Profile of ribs rounded triangular, sharper near the umbil icus and broadening ventral ly. D I S C U S S I O N - None of the known species of Asteroceras shows a volut ion and ornament identical to that of the Queen Char lot te form. The closest resemblance can be observed wi th A. margarita which is, however, characterized by denser r ibbing, par t icular ly on the inner whorls, and narrower umbil icus . A reasonable comparison can be made to some forms described as A. cf. stellare (FUCINI, 1903: p.184, p i . 30, fig. 5; HALL, 1987: p. 1692, p. 1, fig. A - D ) but w i t h o u t seeing a similar rib t rend on the umbi l ica l wall and lower flank. T h e most evolute Asteroceras described by FUCINI (1903, A. volubile) has a lower expansion rate. Should the Queen Char lo t te form represent a new species, our poorly preserved material is inadequate to serve as a basis for comprehensive description. S Y S T E M A T I C P A L E O N T O L O G Y A S TER O CERA TINA E 142 O C C U R R E N C E - Y a k o u n River , Section H , Level 13, Section I, Level 5; K u n g a Island, Section S, Level 25, 27, 36, 44; from the Var ians Zone. D I S T R I B U T I O N - A. margarita is known from Italy and various localities in France (belonging to both the Mediterranean and Northwest European provinces) from the O b t u s u m Zone. A tentat ively synonymized form (SMITH, 1981) occurs in Nevada in the Arnioceras ceratitoides and Paltechioceras harbledownense zones of SMITH. G E N U S Hypasteroceras S P A T H , 1923 T Y P E S P E C I E S - Asteroceras? ceratiticum FUCINI, 1903 (Lectotype: p. 148, p i . 23, fig. la -c , designated by D O N O V A N and F O R S E Y , 1973, p. 8) by original designation (SPATH, 1923, p. 84) S Y N O N Y M Y - Asaphoceras, S P A T H , 1924 (see D O N O V A N , 1990, p. 258 for details). D E S C R I P T I O N - Moderate ly evolute forms wi th med ium to wide umbil icus. Whor l s high w i t h ogival section. Diagnostic high, acute keel on venter. Smooth or very faintly ornamented wi th falcoid ribs. Sutures ceratitic-like on type species. R E M A R K S - W h e n erecting the genus S P A T H (1924) d id not provide any information other than the designation of the type species. D O N O V A N and F O R S E Y (1973) only added the formal designation of the lectotype of the type species. It was not un t i l recently that a more detailed discussion of the species content of genus was given by D O N O V A N (1990). His list of species assigned to the genus includes two other species first known from Italy (H. exiguum (FUCINI, 1903) and H. montn (MENEGHINI, 1877)). "Ammonites falcames laevissimus" of Q U E N S T E D T (1883, p i . 13, fig. 18) was also questionably thought to belong to this genus ( B R A G A et al . , 1984, p. 273),since it has a high simple keel and only faint ornamentat ion. S Y S T E M A T I C P A L E O N T O L O G Y ASTEROCER A TINAE 143 The asteroceratid affinity of the genus was rejected by DONOVAN (1990) on morphological as well as strat igraphic grounds. In our opinion, however, the available stratigraphic information (see below) does support an age range close to that of Asteroceras and the relatively simple suture line wi th broad, l i t t le d ivided lateral saddles is not far from that of Asteroceras. Therefore the original placement into the subfamily Asteroceratinae is retained here. A G E A N D D I S T R I B U T I O N - The following paragraph is intended to provide a comprehensive review of the known occurrences of the genus. H. ceratitoides, H. exiguum, and H. raontii were described from Mon te d i Ce tona in the Cent ra l Appenines by FUCINI (1903). The locali ty is famous for its rich fauna beautifully i l lustrated in the five volumes of FUCINl's work (1901-1905) without much useful stratigraphic information. FISCHER (1971, 1972) a t tempted to recollect the condensed section to remedy the lack of biostrat igraphy. He reported H. montn (1971, p. 103-104) and H. exiguum (1972, p. 44) from beds immediately below a bed yielding Dactilyoceratinae and Harpoceratinae of probable Ca r ix i an age and above beds yielding an Arnioceras assemblage. DONOVAN (1990) tends to interpret a break in the succession below Hyp asteroceras rather than above it wi thout strong reasoning. Strat igraphic evidence presented below favors a T u r n e r i / O b t u s u m Zone age of the Hyp asteroceras fauna as it may follow from a direct relationship wi th the Arnioceras assemblage below and a hiatus above separating it from the Pliensbachian faunas. H. montn has been recorded from other I tal ian localities in Tuscany: Gerfalco (FUCINI, 1898), A r i e t i (DE STEFANI, 1886), and M o n t e d i Coregna (FEDERICI, 1968) without precise biostratigraphic data, also from Palermo, Sic i l ia (GUGENBERGER, 1936) probably erroneously from the B u c k l a n d i Zone. F r o m Spain BRAGA et al . (1984a) figured H.? laevissimum (p. 273, p i . 1, fig. 13) associated wi th Arnioceras ceratitoides; also BRAGA et al. (1984b) listed H. exiguum as a member of their Asteroceras-Arnioceras assemblage correlated wi th the O b t u s u m Zone. H.? laevissimum if indeed referable to this genus is the only representative occurring in the Nortwest European province, namely in the Schwabian A l b . There is no publ ished occurrence of Hypasteroceras outside Europe, although SMITH figured a comparable form wi th sharp, non-sulcate keel as Arnioceras miserabile (1981, p. 144, p i . 2, fig. 2) from his S Y S T E M A T I C P A L E O N T O L O G Y ASTER O CERA TINAE 144 Arnioceras ceratitoides Zone in Nevada. The present author identified a specimen from Tyaugh ton Creek as H. cf. montii ( G S C locality 117232) wi th in a rather unique association or iginat ing probably from between the levels of abundant Arnioceras and echioceratid faunas (TIPPER, pers. comm. 1990) Hyp asteroceras ? sp. PI . 9, F i g . 4-5 M A T E R I A L - T w o fragmentary specimens preserved as flattened impressions. M E A S U R E M E N T S S P E C I M E N N O . D M A X D U D U W H Y L 1 0 1 / 4 A %31.5 12.5 %39.7 10.1 Y L 1 0 1 / 4 B 21.3 8.9 41.8 11.8 D E S C R I P T I O N - Smal l , very evolute form w i t h moderately enlarging whorls and m e d i u m wide umbil icus . H igh keel persistent from an early stage ( U D % 2 mm) . Smooth , no trace of ornament discernible. D I S C U S S I O N - A m o n g the species listed above the closest comparison can be drawn to H. exiguum and H. ceratiticum, the two differing mainly in sutural characteristics. Our individuals differ from the several smooth specimens figured by FUCINI (1903, e. g. p i . 34, fig. 4, 5, 8) by being more evolute. The poor preservation (flattened state, loss of sutures) of the Queen Char lo t te material does not allow the establishment of specific ident i ty . O C C U R R E N C E - Y a k o u n River , Section I, Level 1; from the Var ians Zone. S Y S T E M A T I C P A L E O N T O L O G Y A S TER OCERA TINA E 145 G E N U S Epophioceras SPATH, 1924 T Y P E S P E C I E S - Ammonites Landrioti D'ORBIGNY, 1850 (p. 213, No. 33) nomen dubium clarified by THEVENIN (1907, p. 22, p i . 7, fig. 4-5) and refigured by GUERIN-FRANIATTE (1966, p i . 217). Or ig ina l designation by SPATH (1924, p. 204). D E S C R I P T I O N - Large forms usually of 15-20 c m diameter sometimes at taining even larger size. V e r y evolute wi th large umbi l icus representing 55-70% of diameter. W h o r l section subcircular. Venter smooth bearing a weak keel w i t h or without faint sulci . Ornament consists of dense, simple, radial or prorsiradiate ribs. R E M A R K S - The classification of Epophioceras is discussed by SCHLATTER (1984). He favoured including the genus in the Echioceratidae while the t radi t ional practice is to include it in the Asteroceratinae (e.g. DONOVAN et a l , 1981), a practice followed here. Epophioceras is the root stock of Echioceratidae (GETTY, 1973) and, in turn , is derived from Asteroceras (DONOVAN, 1987). The separation af Asteroceratinae and Echioceratidae is therefore inevi tably arbitrary. The recurrent morphology of evolute, s imply r ibbed shells wi th in several groups of Sinemurian ammonites poses problems for safe identification of Epophioceras. Heterochronous homeomorph genera include Vermiceras, Metophioceras, and Paltechioceras (DONOVAN, 1987). Sutures, which may allow more reliable identification, are missing on the Queen Charlot te material . Precise stratigraphic information (cooccurrence wi th Asteroceras and Arnioceras), however, enables unambigous determination since there is no overlap of the ver t ical range of Epophioceras w i th the genera listed above. A comprehensive treatment of the genus is given by GUERIN-FRANIATTE (1966). M a n y reports in the literature of the homeomorphs mentioned above may represent Epophioceras; a prominent example is a number of specimens described and figured by FUCINI (1902) as Vermiceras (DONOVAN, 1990). S Y S T E M A T I C P A L E O N T O L O G Y ASTEROCERATINAE 146 A G E A N D D I S T R I B U T I O N - In northwest Europe, where it is best understood, Epophioceras occurs in the O b t u s u m Zone. In the Medi terranean province it is known from numerous localities in Spain ( B R A G A et a l , 1985), Italy (FUCINI, 1902), A u s t r i a ( H A U E R , 1856), and Hungary ( G E C Z Y , 1972). Outside Europe it has been recorded from South A m e r i c a (Peru : G E Y E R , 1979, PRINZ, 1985; Chi le : H l L L E B R A N D T , 1981; Argent ina : R l C C A R D I et a l , 1988) as well as N o r t h A m e r i c a (Nevada: S M I T H , 1981; A lbe r t a : H A L L , 1987). Epophioceras aff. carinatum SPATH, 1924 PI. 10, F i g . 3, 7-8 * aff. 1867 Ammonites Landrioti (D'ORBIGNY) - DUMORTIER, p . 128, p i . 23, fig. 1-2 aff. 1924 Epophioceras carinatum sp. nov. - SPATH, p. 204 aff. 1956 Arnioceras monges-lopezi n . sp. - ERBEN, p. 274, p i . 31, fig. 5-6 aff. 1966 Epophioceras carinatum SPATH, 1924 - GUERIN-FRANIATTE, p. 333, p i . 222-223, text-fig. 183 ? 1979 Epophioceras s p , ex gr. carinatum SPATH - GEYER, p. 209, fig. 5e 1981 Epophioceras aff. carinatum SPATH, 1924 - SMITH, p. 158, p i . 3, fig. 4 cf. 1981 Epophioceras cf. carinatum SPATH, 1924 - SMITH, p. 155, p i . 2, fig. 7, 9; p i . 3, fig. 1, 3 cf. 1981 Epophioceras cf. cognitum GUERIN-FRANIATTE - HlLLEBRANDT, p. 506, p i . 3, fig. 2-3 1988 Epophioceras cf. carinatum SPATH, 1924 - M c F A R L A N E , p. 47, p i . 1, fig. 6 M A T E R I A L - F ive fragmentary specimens preserved as three-dimensional but one-sided internal moulds in sandstone, two flattened internal moulds and one flattened external mou ld in shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X D U D U W H P R H W K 9 G / 3 33.2 19.5 58.7 8.1 13 K 9 B / 6 36.9 20.9 56.6 8.3 « 1 5 Y L 1 1 / %110 73.4 66.3 21.7 %23 =«50 %18 D E S C R I P T I O N - Evolute form at ta ining a m a x i m u m diameter over 10 cm. Umbi l i cus increasingly wide representing over 65% in adults. Venter bearing a rather well developed keel flanked by shallow sulci . S Y S T E M A T I C P A L E O N T O L O G Y ASTEROCERATINAE 147 Modera te ly densely r ibbed throughout, r ibb ing density increasing only moderately wi th growth. Ribs more strongly prorsiradiate in juveniles. Ribs reach the ventro-lateral shoulder. D I S C U S S I O N - Our specimens assigned to E. aff. carinatum fall into a smaller and a larger size group, the latter unfortunately represented only by outer whorl fragments. Thus their conspecific nature is somewhat questionable. The closest comparison can be made wi th Epophioceras carinatum, al though the Queen Charlot te form differs by being smaller in size, less densely r ibbed, and having more prorsiradiate ribs. Other closely related forms include E. longicella and E. cognitum. The morphological differences are likely to justify the in t roduct ion of a new species upon avai labi l i ty of more completely preserved material . O C C U R R E N C E - Y a k o u n River , Section H , Leve l 13; K u n g a Island, Section S, Levels 31 and 35; from the Var ians Zone. D I S T R I B U T I O N - E. carinatum is known from the O b t u s u m Zone of France and also from Peru . It may doubtfully be present in Mexico . Individuals more likely to be conspecific wi th our mater ial have been recorded from Nevada (Arnioceras ceratitoides and Paltechioceras harbledownense zones of SMITH, 1981) and Chi le (HlLLEBRANDT, 1981). F A M I L Y E C H I O C E R A T I D A E BUCKMAN, 1913 R E M A R K S - Th i s family contains serpenticone, strongly and simply r ibbed forms. Despite its relatively simple morphologic scheme the family has been the subject of extensive morphological spl i t t ing wi th over 100 species erected (GETTY, 1972). The generic classification is comprehensively revised by GETTY (1973) who recognized six genera, synonymized thirteen, and treated three as nomma dubia. A revision at the species S Y S T E M A T I C P A L E O N T O L O G Y ECHIOCERATIDAE 148 level by the same author remains unpubl ished (GETTY, 1972). GETTY emphasized the taxonomic value of r ibbing patterns as a feature easily quantifiable and adequate for recognizing species. In the crushed material from the Queen Char lot te Islands the preservation also dictates the ut i l i ty of r ibbing as often the only available diagnostic feature. The mult ivar ia te analysis approach proposed by SMITH (1981) is not usable here since the number of useful morphologic variables is reduced by poor preservation. In Europe the echioceratids are of great biostrat igraphic value in the O x y n o t u m and Rar icos ta tum zones. The good stratigraphic control over our echioceratid collection enhances the rel iabi l i ty of taxonomic conclusions and may support the separation of some morphologically very close but strat igraphically distant forms. G E N U S Plesechioceras TRUEMAN et WILLIAMS, 1925 T Y P E S P E C I E S -Echioceras dehcatum BUCKMAN, 1914, by original designation. D E S C R I P T I O N - Serpenticone forms, r ibb ing extremely dense from the innermost whorls later increasing only little in frequency. R ibs may be sl ightly incl ined forward. Venter bearing weak keel and may develop faint sulci but no tr icarinate stage attained. R E M A R K S - Plesechioceras was synonymized wi th Paltechioceras by GETTY (1973). DOMMERGUES (1982) reaffirmed its separate ident i ty based on newly presented evidence regarding the basal Rar icos ta tum Zone age of the type species (as opposed to the Late Rar icos ta tum Zone age of Paltechioceras). He also presented the case for morphological differences, Plesechioceras differing from Paltechioceras by its high and li t t le increasing r ibbing frequency, sl ightly incl ined ribs, weak keel and complete lack of t r icar inat ion. A s P. yakounense is derived from an even lower strat igraphic level (probaly O x y n o t u m Zone equivalent) and otherwise falls into this morphologic group, we are in favour of retaining Plesechioceras. S Y S T E M A T I C P A L E O N T O L O G Y ECHIOCERA TIDAE 149 A G E A N D D I S T R I B U T I O N - Accord ing to DOMMERGUES (1982) the type species is derived from the base of the Rar icos ta tum Zone in France. P. arcticum, a species first known from the Canadian A r c t i c (FREBOLD, 1975) is also recorded from South A m e r i c a (HlLLEBRANDT, 1987). P. yakounense n . sp. extends the range of the genus down to the equivalent of the O x y n o t u m Zone. Plesechioceras yakounense n sp. PI. 12, F i g . 1-2, 5, 7 1981 Paltechioceras harbledownense (CRICKMAY, 1928) - SMITH, p. 187, p i . 4, fig. 9-10; p i . 5, fig. 1, 4 v pars 1988 Paltechioceras harbledownense (CRICKMAY, 1928) - McFARLANE, p. 54, p i . 3, fig. 4-6 only T Y P E - Holotype: Specimen Y L 1 4 / 3 0 (PI. 12, Fig. 2) Paratypes: Y L 1 5 / 1 1 (PI. 12, Fig. 1), Y L 1 4 / 3 2 (PI . 12, Fig. 5). T Y P E L O C A L I T Y - Y a k o u n River , left bank (Section H , Level 16). T Y P E H O R I Z O N - Base of the Harbledownense Zone. E T Y M O L O G Y - Named after the Y a k o u n River , the largest river in G r a h a m Island exposing one of the best Sinemurian sections of the Queen Charlot te Islands and serving as type locali ty. D I A G N O S I S - Costa t ion very dense and steadily increasing in frequency. Ribs prorsiradiate and sl ightly curved forward. Venter bearing a low keel wi th faint sulci . M A T E R I A L - 14 specimens preserved as flattened impressions in shale. S Y S T E M A T I C P A L E O N T O L O G Y ECHIOCERA TIDAE 150 M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U « W H P R H W Holotype 58 32.5 56 15.5 35 ( Y L 1 4 / 3 0 ) Paratypes Y L 1 5 / 1 1 86 49 57 19.5 42 Y L 1 4 / 3 2 81 47 58 19 38 D E S C R I P T I O N - M e d i u m sized, diameter less than 10 cm. Expans ion rate slow to moderate, whorl overlap approximately 10%. Umbi l i cus representing 50-60% of diameter. Larger size specimens show trace of well developed keel. One unusually embedded fragment of venter indicates shallow sulci and faint striation forming forward directed chevron. N o evidence of lateral carinae. Costat ion dense from early stages, number of ribs >10 at an umbi l i ca l diameter of 3 m m , >20 at 10 m m , increasing steadily through ontogeny (F ig . 6-12). Ribs strong, sharp, prorsiradiate, gently curved forward. Strength of r ibbing may decrease on adult body chamber. SYSTEMATIC PALEONTOLOGY ECHIOCERA TIDAE 151 DISCUSSION - P. yakounense differs from both P. ? harbledownense and Paltechioceras aff. boehmi in its ribbing pattern. P. ? harbledownense shows more slowly increasing rib frequency curve, whereas that of P. aff. boehmi becomes constant and then decreases. Furthermore P. ? harbledownense attains larger size and the loss of ribbing strength is more significant on its last whorl. Paltechioceras aff. boehmi is characterized by more rapidly enlarging whorls therefore narrower umbilicus. P. ? aklavikense differs in having more pronounced forward curved ribs. The type species P. delicatum has more slender whorls. OCCURRENCE - Yakoun River, Sections H, I and K; Kunga Island, Section T; from the lower part of the P R H W 40 -30 20 10 -0 Holotype Parctypes Other QCI specimens 0 20 UD (mm) n=24 y=0.58x+14.13 r=0.86 40 Figure 6-12 Rib frequency curves of PltsechioceTds yakounense. S Y S T E M A T I C P A L E O N T O L O G Y ECHIOCERA TIDAE 152 Harbledownense Zone. D I S T R I B U T I O N - Besides the Queen Char lo t te Islands the species is known from Nevada (Harbledownense and Ro thp le t z i zones of SMITH, 1981). Plesechioceras ? cf. aklavikense (FREBOLD, 1975) P L 12, Fig. 6, 8 cf. 1960 Echioceras sensu lato sp. indet. - FREBOLD, p. 17, p i . 5, fig. 1-3 * cf. 1975 Echioceras aklavikense F rebo ld sp. nov. - FREBOLD, p. 9, p. 2, fig. 2-9 T Y P E - Holo type: Echioceras aklavikense FREBOLD, 1975, p i . 2, fig. 2, G S C Type No. 14638. M A T E R I A L - 6 specimens preserved as flattened internal moulds in shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W 709Q/1 %79 46 %58 19.5 21 Y L 2 3 / 5 1 %77 41 %53 19 23 D E S C R I P T I O N - Evolute form of m e d i u m size. Umbi l i cus wide, representing more than 50% of diameter. W h o r l section not known. Venter bearing a well developed, rounded, non-sulcate keel as seen on a ventral fragment associated wi th a larger specimen. Inner whorls densely ribbed, rib frequency increasing very little through ontogeny (F ig . 6-13). Ribs robust, rectiradiate, curved forward strongly at two-third of flank ending rather abrupt ly at ventro-lateral shoulder. S Y S T E M A T I C P A L E O N T O L O G Y ECHIOCERA TIDAE 153 D I S C U S S I O N - FREBOLD (1975) provides a detailed description of the ontogenic development of whorl section and venter. Doubt remains in the identification of our specimens as no such information is available. Th i s form is very closely related to P. ? harbledownense from which it differs by its strongly forward curved ribs not losing strength on outer whorls and by its non-sulcate keel. Thei r rib frequency curves, however, are nearly identical . More abundant and better preserved material may prove them conspecific. A m o n g the Paltechioceras species described from Europe P. bavaricum is the closest morphologically but it differs from our form in its lower rib density and frequent irregular, looped ribs. O C C U R R E N C E - Y a k o u n River , Section H ; Maude Island, Section M ; K u n g a Island, Section S; from the Harbledownense Zone. D I S T R I B U T I O N - P. ? aklavikense is known from the Richardson Mounta ins , Northwest Terri tories, and Melvi l le Island of the A r c t i c Archipelago from beds correlated wi th the Rar icos ta tum Zone of Europe but yielding no other ammonites (FREBOLD 1960, 1975). Plesechioceras ? harbledownense (CRICKMAY, 1928) PI . 11, F i g . 1-5 ? 1889 Arniotites or Celtites (species uncertain) - WHITEAVES, p. 147, p i . 19, fig. 4 * 1928 Melanhippites harbledownense sp. nov. - CRICKMAY, p. 61, p i . 3; p i . 4, fig. a-d (?) ? pars 1981 Paltechioceras cf. P. harbledownense (CRICKMAY) - IMLAY, p. 34, p i . 4, fig. 17, 22 only pars 1988 Paltechioceras harbledownense (CRICKMAY, 1928) - M c F A R L A N E , p. 54, p i . 4, fig. 3, 11 only T Y P E - Melanhippites harbledownense CRICKMAY, 1928, holotype: p i . 3 ( G S C T y p e No . 25679), refigured herein as PI . 11, F i g . 1; paratypes: p i . 4, fig. a-d ( G S C T y p e No . 25680-25683), paratypes 1 and 2 refigured herein as PI . 11, F i g . 5 and 3, respectively. GETTY (1973, p. 26) considered the holotype lost and designated the paratype 1 as neotype quoting a wri t ten communicat ion wi th CRICKMAY who believed this specimen more characteristic to the species than S Y S T E M A T I C P A L E O N T O L O G Y ECHIOCERA TIDAE 154 the other paratypes. The fact that the holotype is in existence renders GETTY's designation of neotype inva l id . M A T E R I A L - Approx ima te ly 40 specimens preserved mostly as flattened internal moulds in shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W Y L 2 0 / 7 %180 104 %58 -64 28 Y L 2 0 / 1 %140 88 %62 -56 27 Y L 2 2 / 2 97 57 59 27 D E S C R I P T I O N - Evolu te form at ta ining large size (diameter over 15 cm). Whor l s enlarging more rapidly than typica l of genus. Ven te r bears a keel possibly flanked by sulci but no lateral carinae. Inner whorls densely r ibbed. R i b b i n g frequency increasing very li t t le w i t h growth (F ig . 6-13). Ribs prorsiradiate, straight on inner whorls and sl ightly arcuate at larger diameter. R i b strength decreases on outer whorls, at large size irregular riblets replacing p r imary ribs. SYSTEMATIC PALEONTOLOGY ECHIOCERA TIDAE 155 PRHW 30 — 20 -10 — 0 / ^^^^n. -A .jm _ -— - ~ — • • — ' .••••**" , . . . - < : : o « ...„::::::-• QCI spacirr Plesechioceras? ho Holotyp Plesechioceras ? he ens Q bledownense PlesechU I P 'bledownense Plesechioc ~l specimens ceras ? aklavikense P irotype No. 2 r a s ? harbledownense Holotype Bs sch ioce ra s ? aklavikenac 1 1 1 i i i i i i I I I 0 20 40 60 80 UD (mm) P. ? harbledownense: n=23 y=0/141x+19.52 r=0.49 P. ? aklavikense: n=9 y=0.191x+14.90 r=0.65 Figure 6-13 Rib frequency curve of Plesechioceras ? harbledownense and P. ? aklavikense. DISCUSSION - CRICKMAY's holotype is a plaster cast of an extremely poorly preserved, flattened external mould showing only the outer two whorls of a larger specimen, whereas the paratypes are fragments of smaller specimens. The species is the type of the genus Melanhippites CRICKMAY, 1928, a genus regarded by GETTY (1973) as a nomen dubium. This judgment can be extended to the species itself, as there is considerable doubt whether the fragmentary paratypes represent the same species as the crushed holotype. The species here is interpreted by the holotype showing high and stable rib frequency and weakened ribs on the outer worls, features readily recognizable in the present better preserved material. It should be emphasized that our material originates from the Sandilands Formation which is correlative with and perhaps identical to the Harbledown Formation, which yielded the type material. Paratype 2 is assumed to be conspecific whereas the other two paratypes including the "neotype" designated by G E T T Y (1973) are too S Y S T E M A T I C P A L E O N T O L O G Y E CHIO CER A TID A E 156 incompletely preserved for meaningful comparison. Accord ing to CRICKMAY (1928) the type material originates from a level well above Arnioceras and it is associated wi th Asteroceras (confirmed by TIPPER, 1976). The exposures at the type locality are highly faulted ( H . W . TIPPER, pers. comm.) . The inner whorls of P. ? harbledownense are pract ical ly indistinguishable from those of other densely r ibbed forms such as P. yakounense, Paltechioceras cf. rothpletzi, and Paltechioceras aff. boehmi. However, they all differ in having more densely r ibbed outer whorls. P. ? aklavikense can be distinguished by its more arcuate ribs. Over and above the rejection of Melanhippites as nomen dubium by GETTY (1973) the generic assignment of this species remains a problem. B o t h morphological and strat igraphical evidence point to an echioceratid affinity (contrasting the arnioceratid allocation proposed originally by CRICKMAY, 1928 and advocated by FREBOLD in FREBOLD and LITTLE, 1962). The rib frequency curve and low stratigraphic position suggests assignment to Plesechioceras , the high last whorl and - obsolete r ibb ing is a feature of Leptechioceras, whereas allocation to Paltechioceras is also a justifiable alternative (BREMER, 1965). O C C U R R E N C E - Y a k o u n River , Section H ; M a u d e Island, Section M ; K u n g a Island, Sections S and T ; from the Harbledownense Zone. D I S T R I B U T I O N - The type locali ty and the Queen Char lot te Islands are the only uncontested occurrences of the species, which may also be present in the Upper Sinemurian of A l a s k a (IMLAY, 1981). G E N U S Paltechioceras BUCKMAN, 1924 T Y P E S P E C I E S - Paltechioceras eliticum BUCKMAN, 1924, p. 483 S Y N O N Y M Y - See GETTY (1973) for a detailed discussion. S Y S T E M A T I C P A L E O N T O L O G Y ECHIOCERA TIDAE 157 D E S C R I P T I O N - Densely r ibbed serpenticones wi th a compressed whor l section. Venter carinate, most often bisulcate and may at tain tricarinate stage. A G E A N D D I S T R I B U T I O N - In Europe Paltechioceras is common in the Rar icos ta tum Zone of both the Northwest European and Medi terranean provinces. It first appears in the Macdone l l i Subzone and reaches its acme in the A p l a n a t u m Subzone (GETTY, 1973). It is generally held that the genus became extinct by the end of Sinemurian (DONOVAN, 1987). It is known from both N o r t h and South Amer i ca . Occurrences from other parts of the world may be hidden in the li teruture due to the easy confusion wi th homeomorph Ear ly Sinemurian forms (e.g. Vermiceras, Metophioceras). Paltechioceras cf. romanicum (TJHLIG, 1900) P L 13, F i g . 1 cf. 1956 Orthechioceras romanicum (UHLIG) totonacorum n . subsp. - ERBEN, p. 339, p i . 40, fig. 4-5 cf. 1965 Paltechioceras romanicum cf. romanicum - BREMER, p. 140, p i . 13, fig. 1 cf. 1965 Paltechioceras romanicum anatolicum n . subsp. - BREMER, p. 141, p i . 13, fig. 2 M A T E R I A L - 2 specimens, one internal and one external mould preserved extremely flattened in shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W Y L 2 9 / 3 %90 « 6 2 %68 19 35 23 Y L 2 9 / 1 %85 53 %62 17 37 23 D E S C R I P T I O N - Evolute form of m e d i u m size, diameter less than 10 cm. Umbi l i cus wide, approximately 65% of diameter. Trace of a well developed keel but presence of sulci cannot be judged due to poor preservation. Densely r ibbed, rib frequency rapidly increasing up to an umbi l ica l diameter of 10-15 m m SYSTEMATIC PALEONTOLOGY ECHIOCERA TIDAE 158 20 -10 — 0 Pqltechioceros cf. QCI specimerls Holotype P. rothpletzi Bose 1894. pl.56 fig.5 Paltecr ioceras cf. rothpletzi 3CI specimens P< Itechioceras sp. Ssecimen H35/1 0 20 40 60 80 100 UD (mm) P. cf. romanicum: n=15 y=0.289x+14.85 r=0.62 P. cf. rothpletzi: n=10 y=0.542x+18.33 r=0.56 P. sp.: n=8 y=0.034x+22.60 r=0.25 Figure 6-14 Rib frequency curve of Paltechioceras cf. romanicum, P. cf. rothpletzi, and P. sp. remaining nearly constant later with approximately 23 ribs per half whorl (Fig. 6-14). Ribs rather sharp, strongly rursiradiate. DISCUSSION - P. romanicum was synonymized with P. tardecrescens by GETTY (1972) in an effort to minimize the number of species within the oversplit genus Paltechioceras. The main arguments presented were overall similarity and resembling rib frequency curves. In our opinion P. romanicum should be retained based on its characteristic rursiradiate ribbing trend what makes it easily distinguishable from all other species of Paltechioceras. OCCURRENCE - Yakoun River, Section H, Level 31; from the Harbledownense Zone. S Y S T E M A T I C P A L E O N T O L O G Y ECHIOCERA TIDAE 159 D I S T R I B U T I O N - In Europe P. romanicum is confined to the Medi terranean Province where it occurs in Ana to l i a , Tu rkey (BREMER, 1965), the Carpa th ian M t n s , R u m a n i a (UHLIG, 1900), and The Southern Appenines, Italy (ONETTI, 1915). Outside Europe it is also known from Mexico (ERBEN, 1956). BREMER correlated it wi th the highest Sinemurian A p l a n a t u m Subzone, support ing ERBEN's allocation of the species into his uppermost Sinemurian " U n i t of Microderoceras bispmatum altespmatum". Paltechioceras cf. rothpletzi (BOSE, 1894) PI . 13, Fig. 5 * cf. 1894 Arietites rothpletzi Bose - BOSE, p. 730, p i . 56, fig. 5 cf. 1902 Vermiceras rothpletzi (BOSE) - FUCINI, p. 139, p i . 12, fig. 12 cf. 1914 Echioceras rothpletzi (BOSE) - BUCKMAN, p. 96c cf. 1965 Paltechioceras rothpletzi (BOSE) - BREMER, p. 143, p i . 13, fig. 4 cf. 1981 Paltechioceras rothpletzi (BOSE, 1894) -SMITH, p. 193, p i . 5, fig. 5-6; p i . 6, fig. 1 cf. 1985 Paltechioceras cf. rothpletzi (BOSE, 1894) - PRINZ, p. 180, p i . 4, fig. 3 cf. 1988 Paltechioceras (?) aff. rothpletzi (BOSE) - CECCA et a l , p i . 1, fig. 5-6 M A T E R I A L - 2 specimens preserved as flattened internal mould in shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W Y L 3 2 / 1 75.8 47 62 16.8 _ 36 33 Y L 3 2 / 2 22 15 68 5 28 D E S C R I P T I O N - Serpenticone shell wi th slowly enlarging whorls and wide umbil icus . Venter not seen. Inner whorls extremely densely r ibbed. R i b frequency increasing up to an umbi l ica l diameter of approximately 10 m m where number of ribs can exceed 30 per half whor l . R ibs straight, rectiradiate to gently prorsiradiate. S Y S T E M A T I C P A L E O N T O L O G Y ECHIOCERA TIDAE 160 D I S C U S S I O N - P. rothpletzi is the most densely r ibbed species of the genus. The Queen Charlot te specimens compare favourably wi th the synonymized material except for their tendency of mainta in ing a nearly constant rib frequency at later growth stage. Th i s form differs from other echioceratids occurring in the Queen Char lot te Islands in its denser costation coupled with a very wide umbi l icus . O C C U R R E N C E - Y a k o u n River , Section H , Level 34; from the upper part of the Harbledownense Zone. D I S T R I B U T I O N - P. rothpletzi is Te thyan in dis t r ibut ion being reported from the Bavarian A l p s (BOSE, 1894), A n a t o l i a (BREMER, 1965) and and Italy (FUCINI, 1902) in Europe as well as from Peru (PRINZ, 1985) and Nevada (SMITH, 1981). It is restricted to the uppermost Sinemurian. Paltechioceras aff. boehmi ( H U G , 1899) PI . 12, F i g . 3-4 * aff. 1899 Arietites boehmi n . sp. - H U G , p. 16, p i . 12, fig. 8 aff. 1902 Vermiceras boehmi H U G - FUCINI, p. 141, p i . 12, fig. 13 aff. 1914 Echioceras boehmi (HUG) - B U C K M A N , p. 96c aff. 1958 Paltechioceras boehmi (HUG) - D O N O V A N , p. 26, p i . 2, fig. 5 (?), 6 aff. 1972 - G E T T Y , p. 222, p i . 8, fig. 3 aff. 1981 Paltechioceras boehmi ( H U G , 1899) - SMITH, p. 176, p i . 4, fig. 1-2 aff. 1986 Paltechioceras bohemi (HUG) (sid) - PALLINI, p i . 1, fig. 2 aff. 1987 Paltechioceras boehmi (HUG) - D O M M E R G U E S and MEISTER, p. 319, p i . 3, fig. 6-16; p i . 4, fig. 1-4 pars 1988 Paltechioceras boehmi ( H U G , 1899) - M C F A R L A N E , p. 56, p i . 4, fig. 5, 6, 8 only 1988 Paltechioceras cf. rothpletzi (BOSE, 1894) - McFARLANE, p. 58, p i . 4, fig. 10, 12; p i . 5, % 2(1) . ? pars ' 1988 Paltechioceras aff. boehmi ( H U G ) - C E C C A et al . , p i . 1, fig. 9 only aff. 1989 Paltechioceras boehmi (HUG) - D O M M E R G U E S and MEISTER, p. 465, p i . 2, fig. 6-11; p i . 3, fig. 2, 5 ' aff. 1990 Paltechioceras boehmi (HUG) - D O M M E R G U E S and MEISTER, p. 319, p i . 4, fig. 2-3 T Y P E - Lectotype: Arietites boehmi H U G , 1899, p i . 12, fig. 8, designated by D O N O V A N , 1958, p. 26; deposited in the Naturhistorisches Museum, Bern , wi th no number. SYSTEMATIC PALEONTOLOGY ECHIOCERA TIDAE 161 MATERIAL - Approximately 35 specimens preserved as flattened internal moulds, some of them with shelly film, in shale. MEASUREMENTS SPECIMEN NO. DMAX UD U WH PRHW YL30/25 49.5 27.5 55 13 28 YL32/21 44 21.9 49.8 12.5 23 YL31/22 38.8 18.5 47.7 11 23 PRHW 3 0 — • 2 0 — 10 — • QCI spec P a l t e c h i o c e r a s i m e n s L e c t o t y D a f f . b o e h m i H a u g , 18|92 e P. b o e h m i , p i . 12, f i g . 8 ~ i 1 1 r 1 1 1 1 10 2 0 UD (mm) Paltechioceras aff. boehmi n=32 y=0.627x+14.58 r=0.66 ~i 1 1 r 0 3 0 Fig. 6-15 Rib frequency curve of Paltechioceras aff. boehmu S Y S T E M A T I C P A L E O N T O L O G Y ECHIOCERA TIDAE 162 D E S C R I P T I O N - Evolute form of small size, diameter typica l ly around 5 cm. Whor l s enlarging rather rapidly for genus, umbil icus approximately half of diameter. Some indicat ion of a keel without lateral carinae. Inner whorls very densely r ibbed, rib frequency increasing up to 10-15 m m of umbi l ica l diameter and 20-30 ribs per half whorl then decreasing slightly (F ig . 6-15). Ribs sharp, prorsiradiate, curved gently forward at ventro-lateral shoulder. D I S C U S S I O N - The densely r ibbed inner whorls and the convex upward rib frequency curve compare favourably wi th P. boehmi. Nevertheless our specimens differ from it in their less slender whorls and narrower umbil icus . P. rothpletzi can be distinguished by the steady cl imb of its rib frequency curve. P . aff. boehmi also seems to be closely related to Plesechioceras yakounense, Plesechioceras ? harbledownense, and Plesechioceras ? aklavikense, their differences are discussed under these species. O C C U R R E N C E - Y a k o u n River , Section H , Levels 32-34; from the Harbledownense Zone. D I S T R I B U T I O N - P. boehmi is known from both Northwest Europe (GETTY, 1972) and the Medi terranean Province (FUCINI, 1902, PALLINI, 1986) but it is most abundant in their t ransit ional region representing the northern margin of the Tethys (e. g. Swiss Prealps, DOMMERGUES and MEISTER, 1987). GETTY (1972) determined its range in Br i t a i n from the top of the Macdone l l i Subzone extending to the A p l a r i a t u m Subzone. DOMMERGUES and MEISTER's results suggest an early Macdone l l i (1987) or late Rar icos ta tum Subzone age for the species. Paltechioceras sp. PL 13, Fig. 6 M A T E R I A L - One shelly specimen preserved one-sided and compressed in shale. S Y S T E M A T I C P A L E O N T O L O G Y ECHIOCERA TIDAE 163 M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W Y L 3 3 / 1 128 83 65 26.5 27 D E S C R I P T I O N - Serpenticone widely umbil icate form. Flanks slightly convex, ventro-lateral shoulder rounded, venter not seen. Inner whorls densely r ibbed wi th a number of ribs exceeding 20 per half whorl at an umbi l i ca l diameter of 5 m m , later remaining largely unchanged as density of ribs decreasing on outer whorls. Ribs stout, gently prorsiradiate, sharper on inner whorls becoming broader and more rounded at later stages. D I S C U S S I O N - The inner whorls of this specimen resemble those of Plesechioceras ? yakounense, P. ? harbledownense, and Paltechioceras aff. boehmi. Plesechioceras ? yakounense can be distinguished by its continuously increasing trend of rib frequency whereas Paltechioceras aff. boehmi tends to show a slight decrease in that along wi th a higher expansion rate. P. ? harbledownense can be distinguished from the present form by the weakening of ribs on outer whorls at comparable size. None of the European species is closely comparable wi th the present form. The assesment of the identi ty of the only available ind iv idua l must await the discovery of more material . O C C U R R E N C E - Y a k o u n River , Section H , Level 35; from the upper part of the Harbledownense Zone. F A M I L Y O X Y N O T I C E R A T I D A E HY A T T , 1875 G E N U S Oxynoticeras H Y A T T , 1875 T Y P E S P E C I E S - Ammonites oxynotus Q U E N S T E D T , 1843 (p. 161) by subsequent designation ( B U C K M A N , 1909, p. 2). S Y S T E M A T I C P A L E O N T O L O G Y OX YNO TICER A TIDAE 164 S Y N O N Y M Y - Hyp oxynoticeras SPATH, 1925 D E S C R I P T I O N - Involute, compressed forms with narrow umbilicus. Whorl section lanceolate with a sharp venter. Ornament consisting of fine ribs in some cases confined to lower flank. Sutures closely spaced and highly complex. A G E A N D D I S T R I B U T I O N - Oxynoticeras is distributed worldwide in the Upper Sinemurian. It is most characteristic of the Oxynotum Zone but ranges as high as the basal Jamesoni Zone of the Pliensbachian (GECZY, 1976). Besides the numerous European occurrences the genus is also known from North America (Arctic Canada: FREBOLD, 1960; Nevada: SMITH, 1981; Mexico: ERBEN, 1956). The only Oxynoticeras recorded from South America (HlLLEBRANDT, 1981) may belong to Radstockiceras (see Discussion under R. ex gr. numismale). Oxynoticeras cf. simpsoni (SIMPSON, 1843) PI. 14, Fig. 2 cf. * cf. cf. cf. cf. cf. pars ? 1876 1886 1912 1961 1976 1981 1988 Amaltheus simpsoni SIMPSON - TATE and BLAKE, p. 291, pi. 8, fig. 4 Oxynoticeras oxynotum (QUENSTEDT) - GEYER, p. 231, pi. 2, fig. 12, 13 Aetomoceras simpsoni BEAN - SIMPSON - BUCKMAN, pi. 66A and B Oxynoticeras simpsoni (Simpson) - DEAN et a l , pi. 67, fig. 4 Oxynoticeras simpsoni (SIMPSON) - SCHLEGELMILCH, p. 53, pi. 22, fig. 11 Oxynoticeras cf. simpsoni (SIMPSON, 1843) - SMITH, p. 207, pi. 7, fig. 1-2 Oxynoticeratide ? - CECCA et a l , p. 70, pi.2, fig. 5 T Y P E - Holotype figured by BUCKMAN, 1912, pi. 66A and B. M A T E R I A L - 4 specimens preserved as flattened impressions with shelly film in shale. S Y S T E M A T I C P A L E O N T O L O G Y OXYNOTICERA TIDAE 165 M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H Y L 1 4 / 3 98 11 11.2 54 Y L 1 4 / 1 1 69.5 7.5 10.8 34.5 Y L 1 4 / 2 4 65 5 7.7 40 Y L 1 4 / 9 50 5.3 10.6 24.5 D E S C R I P T I O N - Involute shell w i t h narrow umbil icus. Preservation obliterates any three-dimensional details. Shel l appears to be entirely smooth. D I S C U S S I O N - G iven the flattened preservation any identification is necessarily tentative. The umbil icus of our individuals is narrower than that of the type material . The lack of r ibbing appears to be the most diagnostic characteristic suggesting comparison wi th O. simpsoni. O C C U R R E N C E - Y a k o u n River , Section H , Level 16; from the Harbledownense Zone. D I S T R I B U T I O N - In Northwest Europe, O. simpsoni is characteristic of the Simpsoni Subzone of the O x y n o t u m Zone (DEAN et a l , 1961). SMITH (1981) records 0. cf. simpsoni from his Upper Sinemurian Rothp le tz i Zone of Nevada. G E N U S Gleviceras BUCKMAN, 1918 T Y P E S P E C I E S - Gleviceras glevense BUCKMAN, 1918 by original designation (BUCKMAN, 1918, p. 289). G. glevense is a subjective junior synonym of G. subguibalianum ( P l A , 1914) (DONOVAN, 1958). S Y N O N Y M Y - Glevumites, BUCKMAN, 1924; Guibaliceras, BUCKMAN, 1918; Riparioceras, SCHINDEWOLF, 1962; Tutchericeras, BUCKMAN, 1918; Victoriceras, BUCKMAN, 1918. S Y S T E M A T I C P A L E O N T O L O G Y OXYNOTICERATIDAE 166 D E S C R I P T I O N - Closely related forms to Oxynoticeras a t taining large size. W h o r l section ogival, venter sharp at young stage becoming rounded wi th growth. Kee l confined to inner whorls. R ibb ing of variable strength and density present on different species. A G E A N D D I S T R I B U T I O N - Gleviceras is common in the Upper S inemur ian of both the Northwest European and Mediterranean provinces. The genus ranges up to the Jamesoni Zone (GECZY, 1976). It is also known from Peru (PRINZ, 1985) and Nevada (SMITH, 1981). Gleviceras cf. subguibalianum ( P l A , 1914) PI. 13, F i g . 2-3 cf. pars 1881 Amaltheus Guibalianus - WRIGHT, p. 385, p i . 45, fig. 1, 2, 5 (non 3, 4) cf. * 1914 Oxynoticeras subguibalianum n . sp. - PlA, p. 11, 96, p i . 5, fig. 5; p i . 6, fig. 9; p i . 9, fig. 1 cf. 1956 Oxynoticeras (Radstockiceras) palomense n . sp. - ERBEN, p. 349, p i . 37, fig. 5 cf. 1958 Oxynoticeras (Gleviceras) subguibalianum PlA- DONOVAN, p. 11, p i . 1 cf. 1965 Gleviceras cf. subguibalianum (PlA, 1914) - BREMER, p. 147 cf. 1973 Gleviceras subguibalianum (VON PlA, 1914) - DONOVAN and FORSEY, p. 9, p i . 2, fig. 1 cf. 1976 Gleviceras subguibalianum (PlA) - SCHLEGELMILCH, p. 54, p i . 23, fig. 1 1985 Gleviceras subguibalianum (PlA 1914) - PRINZ, p. 181, p i . 4, fig. 6 cf. 1987 Gleviceras aff. subguibalianum (PlA) - DOMMERGUES and MEISTER, p. 318, p i . 1, fig. 9, 12-13 1988 Gleviceras sp. indet. - M c F A R L A N E , p. 53, p i . 6, fig. 1 cf. 1989 Gleviceras aff. subguibalianum (VIA.) - DOMMERGUES and MEISTER, p. 464, p i . 1, fig. 1 M A T E R I A L - 3 specimens preserved as flattened impressions in shale. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H Y L 1 5 / 1 3 95 22.7 23.9 40 Y L 1 5 / 2 79 15 18.9 33 S Y S T E M A T I C P A L E O N T O L O G Y OXYNO TICERA TIDAE 167 D E S C R I P T I O N - Involute form at taining a diameter of nearly 10 cm. Umbi l i cus moderately narrow and deep. B o d y chamber nearly V2 whor l long. F ine ly ribbed; ribs rectiradiate, somewhat broadening ventrally, swinging forward near the ventro-lateral shoulder. O n a smaller specimen occasionally intercalat ing secondary ribs originate at lower th i rd of flank. D I S C U S S I O N - F r o m the three closely related species of Gleviceras (G. subguibalianum, G. dons and G. victoris) the best comparison of our material can be drawn wi th G. subguibalianum. The best agreement seen is w i th the Pe ruv ian specimen figured by PRINZ (1985, p i . 4, fig. 6). The other species possess somewhat coarser r ibbing, G. dons is further distinguished by its narrower umbil icus and more frequent secondary ribs. O C C U R R E N C E - Y a k o u n River , Section H , Level 17; K u n g a Island, Section T , Level 42; from the Harbledownense Zone. D I S T R I B U T I O N - G. subguibalianum is known pr imar i ly from the O x y n o t u m Zone of both Northwest Europe (SCHLEGELMILCH, 1976) and the Mediterranean Province (BREMER, 1965) as well as from South A m e r i c a (PRINZ, 1985). G E N U S Radstockiceras BUCKMAN, 1918 T Y P E S P E C I E S - Radstockiceras complicatum BUCKMAN, 1918 (p. 287, p i . 27, fig. 1) by original designation. S Y N O N Y M Y - Carixiceras SPATH, 1925; Fastigiceras BUCKMAN, 1919; Homoxynoticeras BUCKMAN, 1925; Kleistoxynoticeras BUCKMAN, 1925; Metoxynoticeras SPATH, 1922; Phylloxyconites BUCKMAN, 1924; Retenticeras BUCKMAN, 1920. S Y S T E M A T I C P A L E O N T O L O G Y OXYNOTICERA TIDAE 168 D E S C R I P T I O N - Oxynot icera t id wi th extremely narrow, punct i form or closed umbil icus . W h o r l section compressed, lanceolate, venter sharp. Ornament typical ly consisting of fine r ibbing. R E M A R K S - Radstockiceras is used here in a broader sense according to BREMER (1965). S C H L A T T E R (1980) retained the genus Metoxynoticeras suggesting that any unification of genera should depend upon more thorough taxonomic revision. His view is not followed here as the preservation of our material would not allow differentiation of these genera based on suture lines. The . closely related Pl iensbachian Fannmoceras is regarded as a separate genus ( F R E B O L D , 1967, SMITH and TIPPER, in prep.). A G E A N D D I S T R I B U T I O N - Radstockiceras is known from the Upper Sinemurian - Upper Car ix ian (DONOVAN et a l , 1981) of both Northwest and Medi terranean Europe . It is most abundant in the Jamesoni Zone. Radstockiceras ex gr. numismale (OPPEL, 1853) PI . 13, F i g . 4 M A T E R I A L - One specimen preserved as flattened impression in shale. M E A S U R E M E N T S - Specimen No. 2 8 A 3 / 1 D M A X = 3 6 . 3 U D = 3 . 4 U=9.4 W H = 1 7 . 0 D E S C R I P T I O N - Involute form wi th narrow umbil icus representing less than 10% of diameter. W h o r l section and depth of umbil icus cannot be seen. Venter wi th sharp and high keel. P r i m a r y ribs indist inct and rectiradiate on lower flank, bent sl ightly backward at flank and projected forward abrupt ly shortly after. R i b b i n g most prominent at ventro-lateral shoulder, where secondary ribs parallel to prorsiradiate part of primaries intercalated. S Y S T E M A T I C P A L E O N T O L O G Y OXYNO TICER A TIDA E 169 D I S C U S S I O N - Our individual agrees reasonably well with two closely related species, R. numismale and R. oppeli (SCHLOENBACH, 1863). Similar ribbing pattern showing the peculiar trend of ribs can be seen in "Oxynoticeras cf. lymense" (non WRIGHT) of HlLLEBRANDT (1981, p. 507, pi. 3, fig. 7), "Metoxynoticeras numismale" of SCHLATTER (1980, p. 50, pi. 1, fig. 4), "Radstockiceras complanosum" of BREMER (1965, p. 150, pi. 14, fig. 1), "Oxynoticeras numismale" of FUCINI (1901, p. 6, pi. 1, fig. 11), Radstockiceras ex gr. numismale of VENTURI, 1978, p.108, pi. 1, fig. 13, and "Radstockiceras oppeli" of HOFFMAN (1982, p. 150, pi. 10, fig. 1; pi. 11, fig. 2 especially). Our individual, however, displays a well developed keel not seen in the above listed specimens. Nomenclatural problems of the subjective synonyms R. numismale and R. complanosum are clarified by S C H L A T T E R (1980). O C C U R R E N C E - Maude Island, Section M , Level 7; from the Recogni tum Zone. D I S T R I B U T I O N - Both R. numismale and R. oppeli are characteristic of the Jamesoni Zone of Northwest Europe. They also occur at Tethyan localities: R. complanosum (=_ff. numismale) is reported from the Jamesoni Zone (Polymorphus Subzone) of Anatolia, Turkey (BREMER, 1965) and CECCA et al. (1988) records "Metoxynoticeras cf. oppeli" from condensed Upper Sinemurian beds in the Appenines, Italy. A possible South American occurrence is known from Chile (HlLLEBRANDT, 1981, see Discussion). Oxynoticeratidae gen. et sp. indet. PI. 14, Fig. 5 M A T E R I A L - One specimen preserved as flattened impression shale. M E A S U R E M E N T S - Y L 4 8 / 1 5 D M A X = 4 8 . 4 U D = 6 ( ' 7 ) W H = 2 6 ( ? ) P R H W = 1 0 ( ? ) S Y S T E M A T I C P A L E O N T O L O G Y OXYNO TICERA TIDAE 170 D E S C R I P T I O N - Involute form wi th narrow umbil icus . U m b i l i c a l seam of last whor l not clearly seen due to bad preservation. B o d y chamber nearly two th i rd of a whorl . Ornament consisting of broad rectiradiate pr imary ribs becoming prorsiradiate on body chamber and fading out near ventro-lateral shoulder. Fine, faint str iat ion visible between primaries. D I S C U S S I O N - The single, poorly preserved specimen does not permit identification. The closest comparison can be drawn wi th Par oxynoticeras pulchellum (FUCINI, 1901). The five specimens originally figured by FUCINI (1901) represent a wide array of r ibbing wi th ribs varying in number and stregth. Our specimen shows greatest resemblance to FUCINI's PI. 1, F i g . 8. Ano the r figured example, originating from the Jamesoni Zone of Hungary (GECZY, 1976, p i . 1, fig. 2), has fewer ribs. A conclusion, however, must await further finds of this form in the Queen Char lot te Islands. O C C U R R E N C E - Y a k o u n River , Section H , Level 50; from the Recogni tum Zone. S U P E R F A M I L Y E O D E R O C E R A T A C E A E SPATH, 1929 F A M I L Y E O D E R O C E R A T I D A E SPATH, 1929 G E N U S Crucilobiceras BUCKMAN, 1920 T Y P E S P E C I E S - Crucilobiceras crucilobatum BUCKMAN, 1920, by original designation. D E S C R I P T I O N - Evolu te forms wi th slowly enlarging whorls and wide umbil icus . W h o r l section subrectangular to ell ipsoid, venter simple. R i b b i n g dense and persistent, ribs straight, bearing two distant rows of tubercles (spines on shelly individuals) . R E M A R K S - Crucilobiceras and Micro der ocer as are closely related genera displaying significant morphological s imi lar i ty expressed by the evolute shell w i t h bituberculate ornament. In our interpretation S Y S T E M A T I C P A L E O N T O L O G Y EODEROCERATACEAE 171 the difference between them is both stratigraphic and morphologic. Microderoceras herein is restricted to include only late Ear ly Sinemurian (Turner i Zone) forms, whereas Crucilobiceras is confined to the Late S inemur ian (mainly Rar icos ta tum Zone). The latter is also distinguished by a tendency to develop secondary ribs at later growth stages, this is not seen in Microderoceras. A l s o the two rows of tubercles on Crucilobiceras are more distant. Metaderoceras was synonymized wi th Crucilobiceras by ARKELL (1957) and DONOVAN and FORSEY (1973), but treated as an independent genus by DONOVAN et al. (1981). The latter opinion is adopted here, since Metaderoceras has only one row of tubercles and is restricted to the Lower Pl iensbachian. A G E A N D D I S T R I B U T I O N - Crucilobiceras is known from the Rar icos ta tum Zone of Northwest Europe. IMLAY (1981) reports the genus from the uppermost Sinemurian of A l a s k a . Crucilobiceras ? sp. PI . 14, Fig. 1, 6; PI. 15, F i g . 3 M A T E R I A L - 3 specimens preserved as compressed internal moulds, two of them whorl fragments only. M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U W H P R H W 1 A 4 / 1 « 1 1 5 %60 %36 %52 25.3 17 Y L 4 8 / 1 8 %46 %21 %45 %15 14 Y L 4 1 / 1 - - - 16.3 %15 D E S C R I P T I O N - Evolu te form; umbil icus represents nearly half of diameter. W h o r l section and umbi l i ca l shoulder rounded, as far as preservation allows observation. Moderate ly dense r ibbing bears two rows of S Y S T E M A T I C P A L E O N T O L O G Y EODEROCERATACEAE 172 tubercles, inner row about ^/j of flank, outer row close to ventro-lateral shoulder. In one specimen 3 m m long spines preserved. Ribs straight, rectiradiate, weak on umbi l ica l wall and lower flank, most prominent between tubercles, terminat ing abrupt ly at the outer one. D I S C U S S I O N - The poor and fragmentary preservation does not allow specific identification. The style of ornament is indicative of Crucilobiceras, as the secondary r ibbing characteristic to Tetraspidoceras is missing, and the tubercles are more distant than in Microderoceras. O C C U R R E N C E - Y a k o u n River , Section H , Level 43 and 50; central G r a h a m Island, Section L , Level 4; from the Recogn i tum Zone. F A M I L Y C O E L O C E R A T I D A E HAUG, 1910 . G E N U S Tetraspidoceras SPATH, 1926 . T Y P E S P E C I E S - Ammonites quadrarmatus DUMORTIER, 1869, p. 60, by original designation (SPATH, 1926, p. 47). D E S C R I P T I O N - M i d v o l u t e to evolute forms, umbi l icus med ium to wide and shallow, whorl expansion rate slow to moderate. W h o r l section ellipsoid. Ven te r convex, simple. Ornament consisting of dense pr imary ribs bearing two distant spines or tubercles and simple intercalatory secondary ribs. R E M A R K S - Tetraspidoceras and its relationship to related genera (Microderoceras, Vicidmoceras) are discussed by DONOVAN (1990a, b) . In a s l ight ly modified view, Tetraspidoceras is taken here to include forms somewhat variable in volut ion and umbi l i ca l w id th but unified by their bituberculate pr imary and well developed secondary r ibbing. Species assignable to Tetraspidoceras include T. quadrarmatus, T. latispma (REYNES), T. reynesi SPATH, T. fila ('QUENSTEDT), T. nothum (FUCINI), T. birchiades (ROSENBERG), T. S Y S T E M A T I C P A L E O N T O L O G Y EODEROCERATACEAE 173 fuelopi G E C Z Y , T. bimammatum G E C Z Y , "Microderoceras ? sp. A " and "Microderoceras sp. B " of C E C C A et al . (1988, p i . 3, fig. 3-5, and fig. 2, respectively) as well as the two new species in t roduced herein, T. pacificum and T. recognitum. A G E A N D D I S T R I B U T I O N - In Europe Tetraspidoceras is characteristic of the Rar icos ta tum and Jamesoni zones. In Northwest Europe most records suggest earliest Pl iensbachian age in contrast to the Medi ter ranean localities where the strat igraphy is less well understood, but Tetraspidoceras often occurs together wi th Sinemurian forms (e. g. Paltechioceras and oxynoticeratids). T. pacificum occurs also in Ch i l e and the genus is possibly present in Mex ico (Microderoceras aff. birchiades of ERBEN, 1956) and Nevada (Microderoceras cf. birchiades of SMITH, 1981). Tetraspidoceras pacificum n . sp. PI . 14, F i g . 4 1987 Microderoceras sp. - QUINZIO SlNN, p i . 3, fig. 1 H O L O T Y P E - Microderoceras sp. of QUINZIO SINN, 1987, p i . 3, fig. 1, specimen no. S A - 3 3 / 1 , deposited in the Technische Univers i ta t , Be r l in . T Y P E L O C A L I T Y - Section 2, Sierra de Argomedo /S ie r ra Aspera , Cordi l le ra Domeyko, Nor the rn Chi le (QUINZIO SINN, 1987, p. 45.) T Y P E H O R I Z O N - O b t u s u m Zone (?) E T Y M O L O G Y - pacificum refers to the known geographic range of the species (the Pacific margin of the Amer icas) . S Y S T E M A T I C P A L E O N T O L O G Y EODEROCERATACEAE 174 D I A G N O S I S - Evolu te form, whorls enlarging moderately rapidly. Bituberculate , tubercles connected by 2-3 looped ribs. Frequency of tubercles increasing slowly wi th growth. 2-4 secondary ribs developed between each set of tubercles, equal in strength to p r imary ribs except for the mature body chamber where pr imary r ibbing becoming coarser. M A T E R I A L - One compressed external mould preserved in shale. M E A S U R E M E N T S -S P E C I M E N N O . D M A X D U D U W H T H W K 6 S / 1 79.5 40.6 51 22.6 14 (Paratype) Holotype %220 % 70 120 55 46 37 13 D E S C R I P T I O N - Evolute form wi th l i t t le whor l overlap. Umbi l icus represents about 40% of diameter. Whor l s expanding moderately rapidly . W h o r l section ellipsoid, flanks and venter convex as far as it can be judged. Moderately densely r ibbed and bituberculate throughout. Frequency of tubercles increases l i t t le wi th growth, number of pair of tubercles remains less than 15 per half whor l (Figure 6-16). 2-3 looped ribs connecting tubercles, 2-4 secondary ribs intercalated between pairs of tubercles. A l l ribs of approximately equal strength. O n adult body chamber pr imary ribs become blunter and coarser wi th a tendency of coalescence. SYSTEMATIC PALEONTOLOGY EODEROCERATACEAE 175 DISCUSSION - Its ornament makes the new species readily distinguishable from all previously described ones. No other representative of Tetraspidoceras shows looped ribs instead of simple primary ribs on the phragmocone. The Queen Charlotte individual agrees well with the holotype. The discovery of better and more completely preserved material is desirable as no suture line and undistorted whorl section is available yet. OCCURRENCE - Kunga Island, Section T, Level 36; from the Harbledownense Zone. THW 15 - i 10 5 0 ' -' I 1 1 Holot 19E /pe (Quinzi 7, PI. 3, Fi ) Sinn, Par g. 1) Kj atype S/1 mV-1 ... , 1 1 0 10 20 30 40 50 60 UD (mm) Figure 6-16 Tubercle frequency curve of Tetraspidoceras pacificum n. sp. S Y S T E M A T I C P A L E O N T O L O G Y EODEROCERATACEAE 176 D I S T R I B U T I O N - Besides the Queen Char lot te Islands, T. pacificum is only known from the Cord i l l e ra Domeyko of Nor thern Chi l e (QUINZIO SINN, 1987) where it occurs together wi th Arnioceras and Epophioceras therefore the age of the assemblage is regarded as O b t u s u m Zone equivalent. Its stratigraphic posi t ion in the Queen Char lo t te Islands is higher as it cooccurs wi th Paltechioceras. Tetraspidoceras recognitum n . sp. PI . 14, F i g . 8; PI . 15, Fig. 1, 4 ? pars 1899 Microderoceras nothum M G H . in sch. - FUCINI, p. 247, p i . 20, fig. 3 only ? 1900 Microderoceras cfr. Heberti OPPEL - FUCINI, p. 161, p i . 21, fig. 3 T Y P E - Holotype: Specimen 2 8 A 2 / 1 [m]. Paratypes: Specimen 93749 [M] and Y L 4 8 / 1 0 . T Y P E L O C A L I T Y - M a u d e Island, section M . -T Y P E H O R I Z O N - Recogn i tum Zone. E T Y M O L O G Y - recognitum - (La t in "revealed, recognized") for the species having been known since the turn of the century wi thout the recognition of its separate identi ty. D I A G N O S I S - Evolu te shell w i th moderately enlarging whorls. B o d y chamber of approximately one whor l . Densely r ibbed and strongly bituberculate, tubercles being more prominent than ribs. M A T E R I A L - 1 macroconch, 1 microconch and 6 smaller size specimens without obvious sign of matur i ty ; al l are preserved as compressed internal moulds or flattened impressions in shale. S Y S T E M A T I C P A L E O N T O L O G Y EODEROCERATACEAE 177 M E A S U R E M E N T S S P E C I M E N N O . D M A X U D U . W H P R H W 2 8 A 2 / l a [m] 90.7 45.1 49.7 26.4 22 (Holotype) Y L 4 8 / 1 0 83.4 38.5 47.4 23.3 19 (Paratype) Y L 4 8 / 1 59.0 29.0 49.1 %18 15 2 8 A 2 / l b %39 18.8 %48 11.5 14 C-93749 [M] %310 172 55.4 68 24 (Paratype) D E S C R I P T I O N - Macroconch: Evolute shell of large size, diameter nearly 30 cm. Umbi l icus wide representing almost 55% of diameter. U m b i l i c a l wal l low, umbi l ica l shoulder rounded. W h o r l section probably ellipsoid wi th sl ightly convex flanks. Venter bearing no keel. B o d y chamber one whor l long. Phragmocone rather worn, no ornament preserved. O n body chamber gently prorsiradiate ribs of broad, low, and rounded profile connect sharp, conical tubercles located at ^ / y and ^/j of flank. No secondary ribs present. SYSTEMATIC PALEONTOLOGY EODEROCERATACEAE 178 Microconch: Shell of medium size, maximum diameter not exceeding 10 cm (one of the specimens shows a flared rib parallel to peristome, believed to indicate maturity at a diameter of 91 mm). Umbilicus representing approximately half of diameter. Similarly to macroconch, body chamber one whorl long showing better preserved ornament. Persistently densely ribbed (Fig. 6-17) and bituberculate. Tuberculation more prominent than ribbing. Phragmocone eroded on all specimens, although some short spines preserved on outer tubercles. Ribs rursiradiate on umbilical wall becoming rectiradiate on flanks, strongest between tubercles and fading out beyond the outer tubercles. 2-3 faint secondary fibs intercalated between primary ones. PRHW 20 -15 — 10 -5 — • / / / * 1/ / * F / * MS * /If * f l / * 'If * f . . v.' * * * * Holo ype [m] 28A2 A /1 Paratype [M] C-93749 • Paratype [m •> ] YL48/10 QCI specimens [n , ] PI. 2 ni 1899 1. Fig. 3 -Fucini PI. 21, A. 1900 •ig- ^ i -i ' 1 1 1 • i — i — i — i — i — — i — i — i — i — — i — r i t T - 1 t • 1 — i — i — i — 0 0 25 50 75 100 UD (mm) QCI [m] specimens n= 19 y=0.302x+8.00 r=0.93 125 150 Figure 6-17 Primary rib frequency of Tetraspidoceras recognitum. S Y S T E M A T I C P A L E O N T O L O G Y EODEROCERATACEAE 179 D I S C U S S I O N - T w o specimens figured by FUCINI (1899, 1900, see synonymy list) display a style of ornament nearly identical to our mater ial al though the first one is a juvenile ind iv idual . Other closely related forms include Microderoceras sp. B of CECCA et a l . (1988, p i . 3, fig. 2) dist inguished by the dominance of ribs over tubercles and Microderoceras aff. birchiades (FERRETTI, 1975, p i . 23, fig. 1; PALLINI 1986, p i . 1, fig. 5) which possess coarser r ibbing. The new species is thought to be d imorph wi th a [M]:[m] ratio of approximately 3:1. A l l but one indiv idual fall into a 5-10 c m m a x i m u m diameter range (microconchs), inc luding a clearly mature specimen (as indicated by a flared rib at the peristome). A much larger ind iv idua l (macroconch), originated probably from the same horizon, shares most morphologic characteristics. O C C U R R E N C E - Y a k o u n River , Section H , Level 50, M a u d e Island, Section M , Level 8; from the Recogni tum Zone. D I S T R I B U T I O N - The two synonymized specimens were collected from Tuscany and the Cent ra l Appenines, Italy. N o precise stratigraphic information is available. Tetraspidoceras sp. PI. 14, F i g . 7 ? 1956 Microderoceras sp. indet. - ERBEN, p. 364, p i . 41, fig. 12 ? 1981 Microderoceras cf. birchiades ROSENBERG, 1909 - SMITH, p. 241, p i . 10, fig. 2 M A T E R I A L - One whor l fragment (one t h i rd of a whorl) preserved as compressed internal mould . S Y S T E M A T I C P A L E O N T O L O G Y EODEROCERATACEAE 180 D E S C R I P T I O N - W h o r l expansion rate suggests moderately wide umbil icus . Ornament changing, bi tuberculate at the beginning wi th pr imary ribs strongest between tubercles and wi th 2-3 weak secondary ribs, later tubercles becoming bullate then levelled into much, coarser p r imary ribs while secondary ribs disappear. Tubercles located approximately I/5 and ^ / g of flank. D I S C U S S I O N - The change in ornament possibly represents the beginning of matur i ty and differences between the phragmocone and adult body chamber. Reasonable comparison can be drawn between our ind iv idua l and T. nothum which also loses secondary ribs on the body chamber (see lectotype: FUCINI, 1899, p i . 21, fig. 1), but nevertheless has a slower expansion rate. T. birchiades also displays similar ornament but probably has a wider umbil icus . Th i s species, however, is poorly defined the type (ROSENBERG, 1909, p i . 13, T h e herein questionably synonymized material consists of unfortunately s imilar ly fragmentary and imperfectly preserved whor l fragments hence comparison is l imi ted. O C C U R R E N C E - Y a k o u n River , Section H , Level 17; from the base of Harbledownense Zone. D I S T R I B U T I O N - One of the doubtfully synonymized forms occurs in the Upper Sinemurian of Mexico (Uni t of Microderoceras bispmatum altespinatum of ERBEN, 1956), the other is derived from the Harbledownense Zone of Nevada (SMITH, 1981). S Y S T E M A T I C P A L E O N T O L O G Y BIVALVIA 181 C L A S S B I V A L V I A LlNNE S U B C L A S S P T E R I O M O R P H I A O R D E R P T E R I O I D A NEWELL, 1965 S U B O R D E R P T E R I I N A NEWELL, 1965 S U P E R F A M I L Y P E C T I N A C E A RAFINESQUE, 1815 F A M I L Y E N T O L I I D A E TEPPNER, 1922 G E N U S Posidonotis LOSACCO, 1942 T Y P E S P E C I E S - Posidonotis damelln LOSACCO, 1942, by monotypy. S Y N O N Y M Y - Pectmula LEANZA, 1943 D E S C R I P T I O N - F la t , th in , discoidal shells wi th pect in id triangular auricles on both valves. Shell ornament consisting of regular concentric folds and radial ribs result ing in reticulate pattern. Auricles bearing growth lines only. R E M A R K S - A complete revision of the genus is given by DAMBORENEA (1987). A G E A N D D I S T R I B U T I O N - In Nor th A m e r i c a Posidonotis is known from the Upper Sinemurian of Cal i fornia and B r i t i s h Co lumbia . The South A m e r i c a n occurrences (Argent ina , Chi le) are restricted to the Upper Pl iensbachian-Lower Toarc ian , while European localities (in Italy and Greece) yielding the type species are most probably of Toarc ian age. There exist uncertain records of the genus from Japan and northeast Siberia. The dis t r ibut ion pattern is discussed in detail by DAMBORENEA (1987, 1989). S Y S T E M A T I C P A L E O N T O L O G Y BIVALVIA 182 Posidonotis semiplicata ( H Y A T T , 1894) PI. 14, F i g . 3; PI. 15, F i g . 2 * 1894 Monotis semiplicata n . sp. - HYATT, p. 414 1894 Monotis symmetrica n . sp. - HYATT, p. 414 1928 Entolium balteatum sp. nov - CRICKMAY, p. 62, p i . 4, fig. e-g 1933 'Monotis semiplicata" HYATT, 1894 - CRICKMAY, p. 52, p i . 14, fig. 4-7 1933 "Monotis symmetrica" HYATT, 1894 - CRICKMAY, p. 52, p i . 14, fig. 1-3 T Y P E - Monotis semiplicata HYATT, 1894, subsequent designation by CRICKMAY, 1933, p. 52; deposited in the U . S. Nat iona l Museum, No . 30192. M A T E R I A L - The species commonly occur crowding particular bedding planes. H a n d specimens of such surfaces were studied. D E S C R I P T I O N - T h i n , flat shells of subcircular outline, commonly 1 to 1.5 c m in length, rare full-grown specimens up to 3 cm. Shells equivalve, nearly equilateral. Ante r io r and posterior auricles present on both valves, though umbonal region rarely preserved fully, part ly due to commonly overlapping individuals . Dorsal margin forming an angle less than 180°. Ornament consisting of concentric folds and straight radia l ribs resulting in a reticulate pattern. Thei r relative strength variable wi th concentric elements typica l ly prevai l ing. D I S C U S S I O N - The three N o r t h Amer i can nominal species ( P . semiplicata, P. symmetrica and P. balteata) are synonymyzed following the practice of DAMBORENEA (1987, 1989). HYATT's two forms differ only due to post-depositional distort ion. CRICKMAY's dist inct ion of P. balteata was based on differences in strength of concentric and radial ribs which is considered to fall wi th in intraspecific var ia t ion. P. cancellata, known from the South Amer i can uppermost Pliensbachian-lowermost Toarc ian , is very closely related (DAMBORENEA, S Y S T E M A T I C P A L E O N T O L O G Y BIVALVIA 183 1987) and further comparative studies are planned to decide whether or not it is conspecific wi th our form ( D A M B O R E N E A , wri t ten comm.) O C C U R R E N C E - Y a k o u n River , Section H ; M a u d e Island, Section M ; K u n g a Island, Section S; from the Recogni tum Zone. D I S T R I B U T I O N - The type material originates from the Sailor Canyon Format ion in Amer i can Canyon, California. The type of Entolium balteatum comes from the Harbledown Format ion , Harbledown Island; the species is also known from neighboring Vancouver Island ( J E L E T Z K Y , 1976). Its local biostratigraphic value in the Queen Charlot te Islands was first recognized by C A M E R O N and TIPPER (1985). I M L A Y (1981) reported it from the Wrange l l M t n s , A l a s k a . Wherever available, scarce associated ammonites (Crucilobiceras, Plesechioceras ? harbledownense) are indicative of Late Sinemurian age ( C R I C K M A Y , 1928, I M L A Y , 1968, 1981, C A M E R O N and T I P P E R , 1985). CONCLUSIONS 184 C H A P T E R 7 CONCLUSIONS This thesis presents the first detailed systematic study of latest Hettangian to earliest Sinemurian ammonites of the Queen Char lo t te Islands. 61 taxa, allocated to 27 genera, are described. Sunrisites senililevis, Plesechioceras yakounense, Tetraspidoceras pacificum and Tetraspidoceras recognitum are introduced as new species. The stratigraphic d is t r ibut ion of ammonites, documented in measured sections, is used to dist inguish six successive assemblage zones: the Canadensis Zone, "Coroniceras" Zone, A r n o u l d i Zone, Var ians Zone, Harbledownense Zone, and Recogn i tum Zone. O f these only the Canadensis Zone was established earlier, the remaining five are defined here. These zones are recognized throughout the islands and permit high-resolution biostratigraphic subdivis ion of the upper part of Sandilands Format ion and basal Ghost Creek Format ion . Da t ing and correlation of the studied sections is achieved employing this zonal scheme. The total thickness of uppermost Het tangian to lowermost Pl iensbachian strata in sections on K u n g a Island is estimated at 385 m . Compar i son of selected zones in different sections indicates a moderate thickness increase to the south. The contact of the Sandilands Format ion and the overlying Ghost Creek Format ion is diachronous, younging gradual ly to the south. The regional biochronological va l id i ty of the local zones is tested by comparison wi th the ammomite succession of other N o r t h A m e r i c a n Sinemurian localities. Besides the Taseko Lakes area and Nevada, the Queen Charlot te Islands yield one of the most diverse and abundant faunas of this age. A general agreement is found between the faunas of these key areas. Thus the presented data are of cr i t ical importance for constructing a regional biochronological scheme. Intercontinental correlation wi th the northwest European standard zonation is possible. The Canadensis Zone straddles the Het tang ian /S inemur ian boundary, which is best approximated by the first appearance of Badouxia columbiae and Metophioceras spp. The position of the Recogni tum Zone at the S inemur ian /P l iensbach ian boundary has not been unambiguously decided; the majority of evidence points to its Pl iensbachian affinities. C O N C L U S I O N S 185 The ammonite fauna consists of taxa w i t h pandemic, Te thyan , Athabascan , East Pacific, or Pacific d is t r ibut ion. Provinc ia l i sm was not prominent but existed during the S inemur ian t ime. The high proportion of Te thyan forms lends support to the theory suggesting a more southerly original paleolatitude for Wrangel l ia . The dis t r ibut ion pattern of Te thyan forms can be explained by the early opening of the Hispanic Corr idor , proven to be in existence by the Pl iensbachian, although convincing stratigraphic evidence from key areas between the east-central Pacific and western Tethys is lacking. Al te rna t ive ly , the pantropic dis t r ibut ion model cannot be ruled out, although the faunal record from the eastern Tethys is inadequate to either prove or disprove it. The strong representation of Athabascan and East Pacific elements renders long-distance longi tudinal tectonic dislocation of Wrange l l i a unlikely. The paleoecology and taphonomy of ammonites, associated macrofauna, and trace fossils is used for paleoenvironmental reconstruction. The general lack of bioturbat ion, predominance of thin-shelled, presumably pseudo-planktonic bivalves, and the intact preservation ,of fish and a crinoid specimen indicate prevail ing oxygen deficient bo t tom conditions. Occasional occurrences of Chondrites, Zoophycos, and burrows of larger diameter suggest periodic gradual oxygen level increase. Different modes of ammonite preservation are controlled by shell morphology as well as the varying sedimentation rate and diagenetic regime. 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L E V E L G S C F I E L D N U M B E R N U M B E R 1 C-159259 606C 2 C-159258 606B 4 C-159257 606A 5 C-159255 605D 6 C-159254 605C SECTION B Kennecott Poin t ; nor th of a boulder field; lat. 5 3 ° 5 4 ' 2 5 " N , long. 1 3 3 ° 0 9 ' 0 5 " W . L E V E L GSC F I E L D L E V E L GSC F I E L D N U M B E R N U M B E R N U M B E R N U M B E R 1 C-156423 622A 6 C-159262 607B 2 C-159266 608A 7 C-159261 607A 3 C-159265 607E 8 C-159260 606D 4 C-159264 607D 9 C-156425 622C 5 C-159263 607C 9 C-156426 623A 6 C-156424 622B SECTION C Kennecott Poin t ; nor th of Section B and east of Section D separated by a strike-slip fault; lat. 53°54 '30"N, long. 1 3 3 ° 0 9 ' 0 0 " W . L E V E L G S C F I E L D N U M B E R N U M B E R 1 C-156428 623C SECTION D Kennecott Poin t ; west of Section C , on the opposite side of a strike-slip fault; lat. 53°54 '30"N, long. 1 3 3 ° 0 9 ' 2 0 " W . A P P E N D I X 203 L E V E L G S C F I E L D L E V E L G S C F I E L D N U M B E R N U M B E R N U M B E R N U M B I 1 C-159251 604A 15 C-159278 6091 1 C-159291 610J 16 C-159292 610K 2 C-159290 6101 17 C-159277 609H 3 C-159289 610H 18 C-159276 609G 4 C-159288 610G 18 C-156953 13-3TD 5 C-159287 610F 19 C-159275 609F 6 C-159252 604B 20 C-159274 609E 7 C-159286 610E 20 C-156952 13-2TD 7 C-175211 25A 21 C-159273 609D 8 C-159285 610D 22 C-156421 618A 9 C-159284 610C 23 C-159272 609C 10 C-159283 610B 24 C-159271 609B 11 C-159282 610A 25 C-159269 608D 12 C-159281 609L 25 C-159270 609A 13 C-159280 609K 26 C-159268 608C 14 C-159279 609J 27 C-159267 608B 27 C-156980 20-1TD S E C T I O N E Kennecott Poin t ; short section between Sections C and F , bounded by two east-west t rending normal faults; lat. 5 3 ° 5 4 ' 3 5 " N , long. 133°09 '00"W. S E C T I O N F Kennecott Poin t ; nor th of Section E , ends at a boulder field around a large boulder but cont inuat ion traceable by a marker bed further northwest, offset several meters by a strike-slip fault; lat. 5 3 ° 5 4 ' 4 5 " N , long. 1 3 3 ° 0 9 ' 1 5 " W . L E V E L G S C N U M B E R F I E L D N U M B E R L E V E L G S C F I E L D N U M B E R N U M B E R C-156420 C-175219 C-156419 C-156418 C-156417 C-156416 C-175218 C-156406 C-156414 C-175216 C-156405 C-156404 617E 26C 617D 617C 617B 617A 26B 611N 614C 25F 611M 611L 10 11 12 13 14 15 16 17 18 19 20 C-156403 C-156402 C-156401 C-159300 C-159299 C-159298 C-159297 C-159296 C-159295 C-159294 C-159293 611K 611J 6111 611H 611G 611F 611E 611D 611C 611B 611A S E C T I O N G Kennecot t Poin t ; nor th of a boulder field around a large boulder and Section F , base of section is a bed wi th abundant Chondrites; lat. 53°54 '50"N, long. 1 3 3 ° 0 9 ' 0 5 " W . APPENDIX 204 L E V E L G S C F I E L D N U M B E R N U M B E R 13 C-175202 24B 14 C-175201 24A SECTION H Y a k o u n River , west bank, over 300 m nearly continuous exposure, par t ly submerged at higher water levels; lat. 5 3 ° 2 4 ' 4 0 " N , long. 132°16 '20" . L E V E L G S C F I E L D L E V E L G S C F I E L I N U M B E R N U M B E R N U M B E R N U M 1 1 C-159401 Y L 1 24 C-159422 Y L 2 2 2 C-159402 Y L 2 25 C-159423 Y L 2 3 3 C-159403 Y L 3 26 C-159424 Y L 2 4 4 C-159404 Y L 4 27 C-159425 Y L 2 5 5 C-159405 Y L 5 28 C-159426 Y L 2 6 6 C-159406 Y L 6 29 C-159427 Y L 2 7 7 C-175243 2 A 30 C-159428 Y L 2 8 8 C-159407 Y L 7 31 C-159429 Y L 2 9 9 C-159408 Y L 8 32 C-159430 Y L 3 0 10 C-159409 Y L 9 33 C-159431 Y L 3 1 11 C-159410 Y L 1 0 34 ' C-159432 Y L 3 2 12 C-175244 2B 35 C-159433 Y L 3 3 13 C-159411 Y L 1 1 36 C-159434 Y L 3 4 14 C-159412 Y L 1 2 37 C-159435 Y L 3 5 15 C-159413 Y L 1 3 38 C-159436 Y L 3 6 16 C-159414 Y L 1 4 39 C-159437 Y L 3 7 17 C-159415 Y L 1 5 40 C-159438 Y L 3 8 18 C-159416 Y L 1 6 41 C-159439 Y L 3 9 19 C-159417 Y L 1 7 43 C-159440 Y L 4 1 20 C-159418 Y L 1 8 48- C-159442 Y L 4 6 21 C-159419 Y L 1 9 49 C-159443 Y L 4 7 22 C-159420 Y L 2 0 50 C-159444 Y L 4 8 23 C-159421 Y L 2 1 51 C-159445 Y L 4 9 52 C-159446 Y L 5 0 SECTION I Y a k o u n River , west bank, ups t ream from Section H separated by a covered interval at the sharp bend of river; lat. 53°24 '20"N, long. 132°16 '20" . APPENDIX 205 L E V E L GSC F I E L D N U M B E R N U M B E R 1 C-177616 Y L 1 0 1 2 C-177617 Y L 1 0 2 3 C-177618 Y L 1 0 3 4 C-177619 Y L 1 0 4 5 C-177620 Y L 1 0 5 6 C-177621 Y L 1 0 6 7 C-177622 Y L 1 0 7 SECTION J Y a k o u n River , east bank, opposite of Section H , largely dupl icat ing that; lat. 5 3 ° 2 4 ' 4 0 " N , long. 132°16 '20" . SECTION K Quar ry on Queen Charlot te M a i n logging road at K m 26; collection made by R . B . M c F a r l a n e (see MCFARLANE, 1988); lat. 53°24 '40"N, long. 1 3 3 ° 1 8 ' 1 5 " W . SECTION L Roadcut on Ghost M a i n logging road; lat. 5 3 ° 2 5 ' 1 0 " N , long. 133°18 '05 " W . L E V E L G S C F I E L D N U M B E R N U M B E R L E V E L G S C F I E L D N U M B E R N U M B ] 1 C-175231 1A1 8 C-175237 1A8 2 C-175232 1A2 9 C-175238 1A9 3 C-175233 1A3 10 C-175239 1A10 4 C-175234 1A4 11 C-175240 1A11 5 C-175235 1A5 12 C-175241 1A12 7 C-175236 1A7 SECTION M Maude Island, south shore, west of Fann in B a y , westward continuation of Section 8 of CAMERON and TIPPER, 1985; lat. 53°11 '50"N, long. 1 3 2 ° 0 3 ' 0 5 " W . A P P E N D I X 206 L E V E L G S C F I E L D L E V E L G S C F I E L D N U M B E R N U M B E R N U M B E R N U M B E R 1 C-175247 4E1 6 C-175225 28A4 2 C-175246 4D1 7 C-175224 28A3 3 C-175226 28C1 8 C-175223 28A2 4 C-175227 28C2 9 C-175222 28A1 5 C-175228 28C3 float C-175248 4F1 S E C T I O N N Sandilands Island, southeast shore, north of a small inlet; lat. 53°10 '20"N, long. 1 3 2 ° 0 5 ' 1 0 " W . S E C T I O N O Roadcut on Al l i fo rd R o a d a t " K m 2, south of Whiteaves Bay; lat. 53°11 '00"N, long. 1 3 2 ° 0 1 ' 0 5 " W . L E V E L G S C F I E L D N U M B E R N U M B E R 1 C-175229 29A 2 C-175230 29B S E C T I O N P Quar ry on logging road W 100, east of T a s u Sound; lat. 52°48 '10"N, long. 1 3 2 ° 0 1 ' 2 0 " W . L E V E L G S C F I E L D L E V E L G S C F I E L D N U M B E R N U M B E R N U M B E R N U M B E R 1 C-156438 724A 6 C-156443 724F 2 C-156439 724B 7 C-156444 724G 3 C-156440 724C float C-156445 724FL 4 C-156441 724D float C-156432 717B 5 C-156442 724E S E C T I O N Q Quar ry on logging road W 160, east of Tasu Sound; lat. 52°48 '05"N, long. 132°01 '25"W. L E V E L G S C F I E L D N U M B E R N U M B E R 1 C-156433 722A 2 C-156434 722B 3 C-156435 722C float C-156436 722LF float C-156437 722UF float C-156431 717A APPENDIX 207 S E C T I O N R Roadcut on Met r ic M a i n logging road, southeast of Tasu Sound, nor th of Barr ier Bay , collection made by S. T A I T E ; lat. 52°47 '40"N, long. 1 3 1 ° 5 7 ' 3 5 " W . L E V E L G S C F I E L D N U M B E R N U M B E R 1 ST90-06 S E C T I O N S K u n g a Island, northeast shore; lat. 5 2 ° 4 6 ' 2 5 " N , long. 1 3 1 ° 3 3 ' 1 0 " W L E V E L . G S C F I E L D L E V E L G S C F I E L D N U M B E R N U M B E R N U M B E R N U M B E R 1 C-177251 704A ( = K 4 A ) 28 C-177278 708S ( = K 8 S ) 2 C-177252 704B ( = K 4 B ) 29 C-177279 708T ( = K 8 T ) 3 C-177253 704C ( = K 4 C ) 30 C-177280 709A ( = K 9 A ) 4 C-177254 " 704D ( = K 4 D ) 31 C-177281 709B ( = K 9 B ) 5 C-177255 704E ( = K 4 E ) 32 C-177282 709C ( = K 9 C ) 6 C-177256 704F ( = K 4 F ) 33 C-177283 709D ( = K 9 D ) 7 C-177257 704G ( = K 4 G ) 34 C-177285 709F ( = K 9 F ) 8 C-177258 704H ( = K 4 H ) 35 C-177286 709G ( = K 9 G ) 9 C-177259 708A ( = K 8 A ) 36 C-177284 709E ( = K 9 E ) 10 C-177260 708B ( = K 8 B ) 37 C-177287 709H ( = K 9 H ) 11 C-177261 708C ( = K 8 C ) 38 C-177288 7091 (=K9I) 12 C-177262 708D ( = K 8 D ) 38 C-177289 709J ( = K 9 J ) 13 C-177263 708E ( = K 8 E ) 39 C-177290 709K ( = K 9 K ) 14 C-177264 708F ( = K 8 F ) 40 C-177291 709L ( = K 9 L ) 15 C-177265 708G ( = K 8 G ) 41 C-177292 709M ( = K 9 M ) 16 C-177266 708H ( = K 8 H ) ' 42 C-177293 709N ( = K 9 N ) 17 C-177267 7081 (=K8I ) 43 C-177294 709O ( = K 9 0 ) 18 C-177268 708U ( = K 8 U ) 44 C-177295 709P ( = K 9 P ) 19 C-177269 708J ( = K 8 J ) 45 C-177296 709Q ( = K 9 Q ) 20 C-177270 708K ( = K 8 K ) 46 C-177297 709R ( = K 9 R ) 21 C-177271 708L ( = K 8 L ) 47 C-177298 709S ( = K 9 S ) 22 C-177272 708M ( = K 8 M ) 48 C-177299 709T ( = K 9 T ) 23 C-177273 708N ( = K 8 N ) 49 C-177300 709U ( = K 9 U ) 24 C-177274 708O ( = K 8 0 ) 50 C-177302 709W ( = K 9 W ) 25 C-177275 708P ( = K 8 P ) 51 C-177301 709V ( = K 9 V ) 26 C-177276 708Q ( = K 8 Q ) 52 C-177303 709Z ( = K 9 Z ) 27 C-177277 708R ( = K 8 R ) SECTION T K u n g a Island, southeast shore; lat. 5 2 ° 4 5 ' 4 0 " N , long. 1 3 1 ° 3 3 ' 0 0 " W . APPENDIX 208 L E V E L GSC F I E L D N U M B E R N U M B E R 1 C-177304 705A ( = =K5A) 2 C-177305 705B (= = K5B) 3 C-177306 705C (= :K5C) 4 C-177307 705D (-= K5D) 4 C-177309 705F (= = K5F) 5 C-177310 705G 0 =K5G) 6 C-177311 705H ( = =K5H) 7 ' C-177308 705E (= =K5E) 8 C-177312 7051 (= K5I) 9 C-177313 705J (= :K5J) 10 C-177314 705K (= = K5K) 11 C-177315 705L (= :K5L) 12 C-177316 705M (: =K5M) 12 C-177317 705N (= =K5N) 13 C-177318 705O (-=K50) 14 C-177319 705P (= =K5P) 15 C-177320 705Q (= =K5Q) 16 C-177321 705R 0 =K5R) 17 C-177322 705S (= :K5S) 18 C-177323 706A ( = =K6A) 19 C-177324 706B (--=K6B) 20 C-177325 706C ( = K6C) 21 C-177326 706D {--=K6D) 22 C-177327 706E (= =K6E) 23 C-177328 706F (= =K6F) 24 C-177329 706G (: =K6G) 25 C-177330 706H (-=K6H) 26 C-177331 7061 (= K6I) 27 C-177332 706J (= :K6J) 28 C-177333 706K (: =K6K) 29 C-177334 706L (= = K6L) 30 C-177335 706M ( =K6M) 31 C-177336 706N (: =K6N) 32 C-177337 706O (: =K6Q) L E V E L GSC F I E L D N U M B E R N U M B E R 33 C-177339 706Q (= = K6Q) 34 C-177338 706P (= :K6P) 35 C-177340 706R (= =K6R) 36 C-177341 706S (= :K6S) 36 C-177342 706SZ ( =K6SZ) 37 C-177343 706T (= =K6T) 38 C-177344 706U (= rK6U) 39 C-177345 707A (= =K7A) 40 C-177346 707B (= =K7B) 41 C-177347 707C (= =K7C) 42 C-177348 707D (= =K7D) 43 C-177349 707E (= =K7E) 44 C-177350 707F (= =K7F) 45 C-177601 707G (= = K7G) 46 C-177602 707GY (=K7GY) 47 C-177603 707H 0 =K7H) 48 C-177604 7071 (= K7I) 49 C-177605 707J (= :K7J) 50 C-177606 707K ( = K7K) 52 — PLS25 53 — PLS24 54 — PLS23 55 — PLS22 56 C-177608 707M (: =K7M) 57 — PLS21 58 C-177609 707N (: =K7N) 58 — PLS20 59 C-177610 707O (: =K70) 60 C-177611 707P (= =K7P) 61 — PLS19 62 — PLS18 63 C-177612 707Q (: =K7Q) 64 C-177613 707R (: =K7R) 65 C-177614 707S (= =K7S) 66 C-177615 707T (: =K7T) 209 P L A T E S 210 E X P L A N A T I O N O F P L A T E 1 (Figures natural size unless otherwise indicated) ( E n d of phragmocone indicated wi th an arrowhead) Figure 1-2 Juraphyllites cf. transylvanicus ( H A U E R ) 1 Latera l view of compressed internal mould . Specimen 7 1 7 B / 1 , Section P , ex situ, probably A r n o u l d i Zone. 2 Lateral view of compressed internal mould . Specimen 705E/1 , Section T , Level 7, "Coroniceras" Zone. Figure 3, 5-7 Juraphyllites aff. nardii ( M E N E G H I N I ) 3 [Macroconch] Latera l view of compressed internal mould . Specimen Y L 4 7 / 8 , Section H , Level 49, Recogni tum Zone. 5 [microconch] Latera l view of internal mould . Specimen P L S 8 9 - 2 1 / 1 , Section T , Level 57, Recogni tum Zone. 6 [microconch] Latera l view of internal mould . Specimen PLS89-21 /2 , Section T , Level 57, Recogni tum Zone. 7 [Macroconch] V e n t r a l impression. Specimen Y L 4 7 / 9 , Section H , Level 49, Recogni tum Zone. Figure 4 Phylloceras sp. Latera l view of internal mould. .Specimen C-156980/21, Section D , Level 27, Canadensis Zone, x2. Figure 8 Juraphyllites cf. limatus ( R O S E N B E R G , 1909) Latera l view of compressed internal mould . Specimen 7 2 4 Q F / 3 , Section P , ex si tu, probably A r n o u l d i Zone. Figure 9 Juraphyllites sp. Latera l view of compressed internal mould . Specimen 608B/8 , Section D , Level 24, Canadensis Zone. Figure 10, 12 Lytoceras spp. 10 Lateral view of compressed internal mould . Specimen 606B, Section A , Level 2, Canadensis Zone. 12 Lateral view of compressed internal mould . Specimen 611H/2 , Section F , Level 13, Canadensis Zone. Figure 11 Lytoceras sp. Lateral view of compressed internal mould . Specimen 609H/9 , Section D , Level 17, Canadensis Zone E X P L A N A T I O N O F P L A T E 2 (Figures natural size unless otherwise indicated) 212 Figure 1,5 Ectocentrites ? sp. 1 Lateral view of compressed internal mould of whor l fragment. Specimen 611G, Section F , Level 14, Canadensis Zone. 5 Latera l view of compressed internal mould of whor l fragment. Specimen C-156980, Section D , Level 27, Canadensis Zone. Figure 2 Tragolytoceras ? sp. Lateral view of compressed internal mould . Specimen Y L 1 0 / 1 , Section H , Level 12, A r n o u l d i Zone. Figure 3, 7-8 Eolytoceras ? guexi ? T A Y L O R 3 Latera l view of compressed internal mould . Specimen 6101/3, Section D , Level 2, Canadensis Zone 7 Latera l view of compressed internal mould . Specimen 611G/3 , Section F , Level 14, Canadensis Zone. 8 Latex cast of external mould . Specimen 2 5 A / 1 , Section D , Level 7, Canadensis Zone. Figure 4 Adnethiceras cf. adnethicum ( H A U E R ) Latex cast of external mould . Specimen 706O/2 , Section T , Level 32, A r n o u l d i Zone. Figure 6 Audaxlytoceras aff. audax ( M E N E G H I N l ) Lateral view of compressed internal mould . Specimen 7 2 4 A / 1 , Section P , Level 1, A r n o u l d i Zone. E X P L A N A T I O N O F P L A T E 3 (Figures natural size unless otherwise indicated) 214 F igure 1, 4 Eolytoceras tasekoi F R E B O L D 1 Latera l view of weathered internal mould . Specimen 610H/2 , Section D , Level 3, Canadensis Zone. 4 Latera l view of compressed internal mould . Specimen 6 1 0 B / 1 , Section D , Level 10, Canadensis Zone. F igure 2, 3 Sulciferites cf. trapezoidalis ( S O W E R B Y ) 2 Latera l view of compressed internal mould . Specimen 610A/6 , Section D , Level 11, Canadensis Zone. 4 Latex cast of external mould of ventral impression. Specimen 609D/11 , Section D , Level 21, Canadensis Zone. F igure 5 Angulaticeras spezianum ( C A N A V A R l ) Latera l view of compressed internal mould . Specimen 724D/1 , Section P , Level 4, A r n o u l d i Zone. F igure 6 Sulciferites ? sp. Latera l view of compressed internal mould . Specimen 704F/7 , Section S, Level 6, "Coroniceras" Zone. F igure 7, 10 Badouxia cf. occidentalis ( F R E B O L D ) 7 Latera l view of compressed in ternal mould . Specimen 611G, Section F , Level 14, Canadensis Zone. 10 Latera l view of compressed internal mould . Specimen 617E/6 , Section F , Level 1, Canadensis Zone. F igure 8 Sulciferites marmoreus ( O P P E L ) Latera l view of compressed internal mould . Specimen 609E/4 , Section D , Level 20, Canadensis Zone. F igure 9 Angulaticeras cf. ventricosum ( S O W E R B Y ) Latera l view of compressed internal mould . Specimen 610H, Section D , Level 3, Canadensis Zone. E X P L A N A T I O N O F P L A T E 4 (Figures natural size unless otherwise indicated) 216 F i g u r e 1-2 Badouxia oregonensis T A Y L O R 1 Latera l view of compressed internal mould . Specimen 617E, Section F , Level 1, Canadensis Zone. 2 Latera l view of latex cast of external mould . Specimen 6 0 4 A / 5 , Section D , Level 1, Canadensis Zone. F i g u r e 3 Badouxia columbiae ( F R E B O L D ) Latera l view of compressed in ternal mould . Specimen 609E, Section D , Level 21, Canadensis Zone. F i g u r e 4 Badouxia aff. occidentalis ( F R E B O L D ) Latera l view of compressed in ternal mould . Specimen 614C/1 , Section G , Level 28, Canadensis Zone. F i g u r e 5 Badouxia ? sp . Latera l view of latex cast of external mould . Specimen 611N/2 , Section F , Level 6, Canadensis Zone. E X P L A N A T I O N O F P L A T E 5 (Figures natural size unless otherwise indicated) 218 F i g u r e 1-2, 6 Badouxia canadensis ( F R E B O L D ) 1 Lateral view of compressed internal mould . Specimen 611G, Section F , Level 14, Canadensis Zone. 2 Latera l view of compressed internal mould . Specimen 610D, Section D , Level 8, Canadensis Zone. 6 Lateral view of internal mould of juvenile ind iv idua l . Specimen 610E, Section D , Level 7, Canadensis Zone. F i g u r e 3 -4 , 8 Badouxia columbiae ( F R E B O L D ) 3 Latera l view of compressed internal mould . Specimen 609F /1 , Section D , Level 19, Canadensis Zone. 4 Lateral view of compressed internal mould . Specimen 606C, Section A , Level 1, Canadensis Zone. 8 Lateral view of compressed internal mould . Specimen 618A, Section D , Level 22, Canadensis Zone. F i g u r e 5, 9 Sunrisites senililevis n . s p . 5 Paratype. La te ra l view of latex cast of external mould . Section F , Level 6, Canadensis Zone. 9 Holotype. Internal mould . Specimen C-143327/c, Castle Pass near Tyaugh ton Creek, Taseko Lakes area, G S C locality C-143327, Canadensis Zone. F i g u r e 7 Vermiceras sp . Latera l view of compressed internal mould . Specimen C-156980, Section D , Level 27, Canadensis Zone. E X P L A N A T I O N O F P L A T E 6 (Figures natural size unless otherwise indicated) 220 Figure 1, 5 Vermiceras ex gr. coregonense ( S O W E R B Y ) 1 Latera l view of compressed internal mould . Specimen 610C, Section D , Level 9, Canadensis Zone. 5 La te ra l view of compressed internal mould . Specimen 609H, Section D , Level 17, Canadensis Zone. Figure 2 Vermiceras cf. supraspiratum ( W A E H N E R ) Latera l view of compressed internal mould . Specimen 604A/4 , Section D , Level 1, Canadensis Zone. Figure 3, 6 Metophioceras aff. roiarium ( B U C K M A N ) 3 Latera l view of compressed internal mould . Specimen 607E, Section B , Level 3, Canadensis Zone. 6 La te ra l v i e w of compressed internal mould . Specimen C-156980, Section D , Level 27, Canadensis Zone. Figure 4, 8 Vermiceras sp. 4 V e n t r a l v i e w of internal mould of unusually embedded individual . Specimen C-156980, Section D , Level 27, Canadensis Zone. 8 Latera l view of internal mould . Specimen C-156980, Section D , Level 27, Canadensis Zone. Figure 7 Coroniceras ? sp. Latera l view of compressed internal mould . Specimen 607C, Section B , Level 6, "Coroniceras" Zone. E X P L A N A T I O N O F P L A T E 7 (Figures natural size unless otherwise indicated) 222 Figure 1 Metophioceras cf. rursicostatum ( F R E B O L D ) Latera l view of compressed internal mould . Specimen C-156980, Section D , Level 27, Canadensis Zone. Figure 2 Arnioceras miserabile ( Q U E N S T E D T ) Latera l view of compressed internal mould . Specimen 2 A / 1 , Section H , Level 7, A r n o u l d i Zone. Figure 3 Arnioceras cf. densicosta ( Q U E N S T E D T ) 7 0 6 E / 1 , Section T , Level 22, A r n o u l d i Zone.Lateral view of compressed internal mould . Specimen Figure 4 Metophioceras spp. Latera l view of compressed internal mould . Specimen 605D/2 , Section A , Level 5, Canadensis Zone. Figure 5 Arnioceras sp. Latera l view of compressed internal mould . Specimen 622B, Section B , Level 6, "Coroniceras" Zone. Figure 6 Arietitinae gen. et sp. indet. Latera l view of compressed internal mould of whorl fragment. Specimen 607B, Section B , Level 6, "Coroniceras" Zone. E X P L A N A T I O N O F P L A T E 8 (Figures natural size unless otherwise indicated) 224 F i g u r e 1 Arnioceras cf. oppeli G U E R I N - F R A N I A T T E Latera l view of compressed internal mould . Specimen K 9 I / 1 , Section S, Level 38, Var ians Zone. F i g u r e 2 Arnioceras e x gr . mendax F U C I N I Latera l view of compressed internal mould . Specimen K 6 L / 9 , Section T , Level 29, A r n o u l d i Zone. F i g u r e 3 Arnioceras arnouldi ( D U M O R T I E R ) Latera l view of internal mould . Specimen 717A, Section Q , ex situ, probably A r n o u l d i Zone. E X P L A N A T I O N O F P L A T E 9 (Figures natural size unless otherwise indicated) 226 Figure 1, 2 Arnioceras arnouldi ( D U M O R T I E R ) 1 V e n t r a l view of internal mould of whorl fragment. Specimen ST90-06, Section R , A r n o u l d i Zone. 2 Latera l view of internal mould of whorl fragment. Same specimen as Figure 1. Figure 3, 6 Arnioceras cf. speciosum FUCINI 3 Lateral view of compressed internal mould . Specimen 706P/1 , Section T , Level 34, A r n o u l d i Zone. 6 Latera l view of compressed internal mould . Specimen 7061/1, Section T , Level 26, A r n o u l d i Zone. Figure 4-5 Hypasteroceras ? sp. 4 Latera l view of compressed internal mould . Specimen Y L 1 0 1 / 4 , Section I, Level 1, Var ians Zone. 5 Lateral view of compressed internal mould . Specimen Y L 1 0 1 / 3 , Section I, Level 1, Var ians Zone. 228 E X P L A N A T I O N O F P L A T E 10 (Figures natural size unless otherwise indicated) ( E n d of phragmocone indicated wi th an arrowhead) F i g u r e 1-2 Arnioceras e x gr . ceratitoides ( Q U E N S T E D T ) 1 Latera l view of compressed internal mould . Specimen Y L 8 / 3 , Section H , Level.9, A r n o u l d i Zone. 2 Latera l view of internal mould. Specimen Y L 1 1 / 7 , Section H , Level 13, Var ians Zone. F i g u r e 3, 7-8 Epophioceras aff. carinatum S P A T H 3 Latera l view of compressed internal mould . Specimen Y L 1 1 / 2 , Section H , Level 13, Var ians Zone. 7 Latera l view of inner whorls of internal mould . Specimen Y L 1 1 / 2 1 , secH, Level 13, Var ians Zone, x2. 8 Latera l view of compressed internal mould . Specimen Y L 1 1 / 3 , Section H , Level 13, Varians Zone. F i g u r e 4, 6 Asteroceras cf. varians F U C I N I 4 Latera l view of internal mould of whorl fragment. Specimen Y L 1 1 , Section H ,Leve l 13, Var ians Zone. 6 Latera l view of compressed internal mould . Specimen Y L 1 0 6 / 1 , Section I, Level 6, Var ians Zone. F i g u r e 5 Asteroceras aff. margarita ( P A R O N A ) Latera l view of latex cast of external mould . Specimen 7 0 9 E / 1 , Section S, Level 36, Var ians Zone. F i g u r e 9 Asteroceras saltriense ? ( P A R O N A ) Latera l view of compressed internal mould . Specimen 715A, Section M , ex si tu, probably Var ians Zone. E X P L A N A T I O N O F P L A T E 11 (Figures natural size unless otherwise indicated) 230 F i g u r e 1-4 Plesechioceras ? harbledownense ( C R I C K M A Y ) 1 Holotype of Melanhippites harbledownense CRICKMAY, 1928. Lateral view of plaster cast of external mould . G S C Type N o . 25679, Harbledown Island. 2 Lateral view of latex cast of external mould of inner whorls. Specimen 707H/10, Section T , Level 47, Harbledownense Zone. 3 Paratype No. 2 of Melanhippites harbledownense CRICKMAY, 1928. Latera l view of latex cast of external mould . G S C Type No . 25681, Harbledown Island. 4 Latera l view of compressed internal mould . Specimen Y L 2 0 / 7 , Section H , Level 22, Harbledownense Zone. F i g u r e 5 Plesechioceras ? harbledownense ? ( C R I C K M A Y ) Paratype No . 1 of Melanhippites harbledownense CRICKMAY, 1928 (Designated as neotype by GETTY, 1973). Latera l view of compressed internal mould . G S C Type No. 25680, Harbledown Island. E X P L A N A T I O N O F P L A T E 12 (Figures natural size unless otherwise indicated) 232 F i g u r e 1-2, 5, 7 Plesechioceras yakounense n sp. 1 Paratype. Latera l view of compressed internal mould . Specimen Y L 1 5 / 1 1 , Section H , Level 17, Harbledownense Zone. 2 Holotype. Latera l view of compressed internal mould . Specimen Y L 1 4 / 3 0 , Section H , Level 16, Harbledownense Zone. 5 Paratype. Latera l view of compressed internal mould . Specimen Y L 1 4 / 3 2 , Section H , Level 16, Harbledownense Zone. 7 Lateral view wi th fragment of venter of compressed internal mould . Specimen Y L 1 0 6 / f l , Section I, ex s i tu , probably Harbledownense Zone. F i g u r e 3-4 Paltechioceras aff. boehmi ( H U G ) 3 Lateral view of compressed -internal mould . Specimen Y130/31, Section H , Level 32, Harbledownense Zone. 4 Latera l view of compressed internal mould . Specimen Y131/22, Section H , Level 33, Harbledownense Zone. F i g u r e 6, 8 Plesechioceras ? cf. aklavikense ( F R E B O L D ) 6 Lateral view of compressed internal mould . Specimen Y L 2 2 / 1 6 , Section H , Level 24, Harbledownense Zone. 8 Latera l view of compressed internal Section H , Level 24, Harbledownense Zone. mould . Specimen Y L 2 3 / 5 1 , E X P L A N A T I O N O F P L A T E 13 (Figures na tura l size unless otherwise indicated) ( E n d of phragmocone indicated wi th an arrowhead) 234 Figure 1 Paltechioceras cf. romanicum (TJHLIG) Latera l view of compressed internal mould . Specimen Y L 2 9 / 3 , Section H , Level 31, Harbledownense Zone. Figure 2-3 Gleviceras cf. subguibalianum ( P l A ) 2 Latera l view of compressed internal mould . Specimen Y L 1 5 / 1 0 , Section H , Level 17, Harbledownense Zone. 3 Latera l view of compressed internal mould . Specimen Y L 1 5 / 1 2 , Section H , Level 17, Harbledownense Zone. Figure 4 Radstockiceras ex gr. numismale ( O P P E L ) Latera l view of compressed internal mould . Specimen 28A3, Section 1 M , Level 7, Recogni tum Zone. Figure 5 Paltechioceras cf. rothpletzi (BOSE) Latera l view of compressed internal mould . Specimen Y L 3 2 / 2 , Section H , Level 34, Harbledownense Zone. Figure 6 Paltechioceras sp. Latera l view of internal mould wi th some shell material . Specimen Y L 3 3 / 1 , Section H , Level 35, Harbledownense Zone. E X P L A N A T I O N O F P L A T E 14 (Figures na tura l size unless otherwise indicated) ( E n d of phragmocone indicated wi th an arrowhead) 236 Figure 1, 6 Crucilobiceras ? sp. 1 Latera l view of compressed internal mould . Specimen 1 A 4 / 1 , Section L , Level 4, Recogni tum Zone. 6 Latera l view of compressed internal mould of whor l fragment. Specimen Y L 4 8 / 1 8 , Section H , Level 50, Recogn i tum Zone. Figure 2 Oxynoticeras cf. simpsoni (SIMPSON) Latera l view of compressed internal mould . Specimen Y L 1 4 / 1 1 , Section H , Level 16, Harbledownense Zone. Figure 3 Posidonotis semiplicata ( H Y A T T ) Impressions of shells on bedding plane. Specimen Y L 4 6 / 2 , Section H , Level 48, Recogn i tum Zone. Figure 4 Tetraspidoceras pacificum n. sp. Para type . Latera l view of latex cast of external mould . Specimen 706S/1, Section T , Level 36, Harbledownense Zone. Figure 5 Oxynoticeratidae gen. et sp. indet. Latera l view of compressed internal mou ld . Specimen Y L 4 8 / 1 5 , Section H , Level 50, Recogni tum Zone. Figure 7 Tetraspidoceras sp. Latera l view of compressed internal mould of whor l fragment. Specimen Y L 1 5 / 1 , Section H , Level 17, Harbledownense Zone. Figure 8 Tetraspidoceras recognitum n. sp. [microconh] Holotype. Latera l view of internal mould . Specimen 2 8 A 2 / 1 , Section M , Level 8, Recogni tum Zone. B o d y chamber slightly longer than one whorl . E X P L A N A T I O N O F P L A T E 15 (Figures natural size unless otherwise indicated) 238 Figure 1, 4 Tetraspidoceras recognitum n. sp. 1 [microconch] Para type . Latera l view of compressed internal mould . Specimen Y L 4 8 / 1 0 , Section H , Level 50, Recogni tum Zone. 4 [Macroconch] Para type . Latera l view of compressed internal mould . Specimen 93749, Section M , ex si tu , probably Recogni tum Zone, x0.66. B o d y chamber slightly longer than one whorl . Figure 2 Posidonotis semiplicata (HYATT) Impressions of shells on bedding plane. Specimen 2 8 A 4 / 1 , Section M , Level 6, Recogni tum Zone. Figure 3 Crucilobiceras ? sp. Latera l view of internal mou ld of whor l fragment. Specimen Y L 4 1 / 1 , Section H , Level 43, Recogn i tum Zone. P L A T E 15 239 E X P L A N A T I O N O F P L A T E 16 (Figures natural size unless otherwise indicated) 240 Figure 1 Phricodoceras sp. Lateral view of compressed internal mould . Specimen 707S/1, Section T , Level 65, Imlayi Zone. Figure 2 Fish remains Latera l view. Specimen 609D, Section D , Level 21, Canadensis Zone. Figure 3 Miltoceras sp. Latera l view of compressed internal mould . Specimen Y L 4 9 / 1 , Section H , Level 51, Imlayi Zone. Figure 4 Gemmellaroceras sp. Latera l view of compressed internal mould . Specimen Y L 4 9 / 1 , Section H , Level 51, Imlayi Zone. Figure 5 Alsatites cf. proaries ( N E U M A Y R ) Latera l view of compressed internal mould wi th some shell material . Specimen 2 4 C / 1 , Section G , Level 10, Upper Het tangian. E X P L A N A T I O N O F P L A T E 17 (Figures na tura l size unless otherwise indicated) Figure 1, 5 Camptonectes (Camptochlamys) sp. 1 Left valve, Specimen Y L 1 4 / 3 1 , Section H , Level 16, Harbledownense Zone. 5 Righ t valve, Specimen Y L 1 7 / 5 , Section H , Level 19, Harbledownense Zone. Figure 2, 11 Otapiria sp. A 2 Largest ind iv idua l : left valve, Specimen Y L 2 3 / 5 2 , Section H , Level 25, Harbledownense Zone. 11 Left valve, Specimen Y L 3 1 / 1 0 , Section H , Level 33, Recogni tum Zone. Figure 3 Pteriacea gen. et sp. indet. 1 Specimen Y L 1 4 / 1 8 , Section H , Level 16, Harbledownense Zone. Figure 4 , 7 Pteriacea gen. et sp. indet. 2 4 Specimen 609H/13 , Section D , Level 17, Canadensis Zone. 7 Specimen 609D/15, Section D , Level 21, Canadensis Zone. Figure 6 Pseudomytiloides sp. Specimen Y L 1 4 / 1 6 , Section H , Level 16, Harbledownense Zone. Figure 8 Limea ? sp. Specimen 610F /5 , Section D , Level 5, Canadensis Zone. Figure 9 Oxytoma sp. Specimen 706H/6 , Section T , Level 25, A r n o u l d i Zone. Figure 10 Ichthyosaur vertebral centrum Specimen Y L 3 8 / 1 , Section H , Level 40, Recogni tum Zone. Figure 12 Isocrinida gen. et sp. indet. C a l i x w i t h part of column, Specimen 6 2 4 A / 1 , Section D , 1 m above Level 26, Canadensis Zone. 

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