Bulletins of American Paleontology Vol. LVII

HARVARD UNIVERSITY

LIBRARY

OF THE

Museum of Comparative Zoology

W^^i^Tlve zoology

^''""HaTva/univerBity

BULLETINSOF

AMERICANPALEONTOLOGY

VOL. LVll

1969- 1970

Paleontological Research Institution

Ithaca, New York 14850U.S.A.

MU3. COivV.-'. 2-0011LIBRARV

APR 27 i970

HARVARDUNlVERSlTYi

INDEX

No separate index is included in the volume. Kach number isindexed separately. Contents of the volume are listed in the begin-ning of the xolume.

CONTENTS OF VOLUME LVII

Bulletin No. Plates Pages

255. The Ammonite Fauna of the KialagvikFormation at Wide Bay, Alaska Penin-sula. Part II. Sonninia Sowerbyi Zone(Bajocian).

By Gerd E. G. Westermann 1-226 1-47

256. New Middle Jurassic Ammonitina fromNew Guinea.

By G. E. G. Westermann andT.A.Getty 227-321 48-62

'z3'-Bi'-'JUS. COMP. 200L'.

BULLETINS dec 3 'OF HARVARD

AMERICAN *'""'"PALEONTOLOGY

Vol. 57

No. 255

THE AMMONITE FAUNA OF THE KIALAGVIKFORMATION AT WIDE BAY, ALASKA PENINSULA.

PART II. SONNINIA SOWERBYI ZONE(BAJOGIAN)

By

Gerd E. G. Westermann

1969

Paleontological Research InstitutionIthaca, New York

U. S. A.

PALEONTOLOGIGAL RESEARCH INSTITUTION1968 - 1969

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BULLETINS OF AMERICAN PALEONTOLOGYand

PALAEONTOGRAPHICA AMERICANA

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BULLETINSOF

AMERICANPALEONTOLOGY

(Founded 1895)

Vol. 57

No. 255

THE AMMONITE FAUNA OF THE KIALAGVIKFORMATION AT WIDE BAY, ALASKA PENINSULA.

PART II. SONNINIA SOWERBYI ZONE(BAJOCIAN)

By

Gerd E. G. Westermann

November 20, 1969

Paleontological Research Institution

Ithaca, New York 14850, U.S.A.

Library of Congress Catalog Card Number: GS 6If-135

Printed in the United States of AmericaArnold Printing Company

CONTENTS

Page

Abstract 5

Preface 5

Stratigraphy 8

Upper boundary and correlation of the Kialagvik Formation 8

Biostratigraphy of the Kialagvik Formation 17

Erycitoidcs hoivclli Zone 17

Sonninla soivcrbyi Zone 18

Otoites saiizei Zone 22

Faunal relations and ages of the iS". soiverbyi Zone assemblages 22

Conclusions 30

Diversity and paleolatitude 31

Fossil localities 32

Systematic description 36

Repository of types 36

Measurements of ammonite shells 36

Family Phylloceratidae Zittel 36

Genus Phylloceras Suess 36

Genus Partschiccras Fucini 38

Genus Holcophylloccras Spath 40

Family Lytoceratidae Neumayr 42

Genus Lytoccras Suess 42

Family Strigoceratidae Buckman 44

Genus Hcbctoxyites Buckman 44

Faiiiil\- Oppeliidae Bunarelli 47

Genus liraJfordiit Buckman 48

Fainil\- Hildoceratidae Hyatt 52

Genus Psi-udoliocnas Buckman 52

Genus Asthcnocrras Buckman 61

Famil\ Ilammatoceratidae Buckman 63

Genus Eudmctoccras Buckman 72

Appendix : /f//4///7o

THE AMMONITE FAUNA OF THE KIALAGVIKFORMATION AT WIDE BAY, ALASKA PENINSULAPART II. SONNINIA SOWERBYI ZONE (BAJOCIAN)

Gerd E. G. WestermannMcMaster University, Hamilton, Ontario

ABSTRACTThe contact between Kialagvik and Shelikof Formations is now drawn at

the base of the Callovian regional unconformity; this accords with the originaldefinition and eliminates strong heterochroneity.

The Sori/iitiia soivcrbyi (Standard) Zone is represented by, below, at least35 m subgreywacke, greywacke, and mudstone containing the Eudmctocerasamplcctcns assemblage [. amplcctcns zonule] and, above, 50-100 m dark shaleswith concretions containing the Pseudocidoccras assemblage [Pscudocidoceraszonule.] Part of the incompetent shales are often missing due to strike-slipfaulting above the E. amplcctcns zonule. The underlying E. hoivcHi Zone isseparated by 80-100 m poorly exposed, unfossiliferous, and little investigatedelastics; the overlying 0. sauzei Zone is separated by 110-130 m unfossiliferoussandstone and shale.

The E. amplcctcns zonule has yielded Eudmctoceras (Euaptctoccras) am-plcctcns (Buckman), Docidoccras (?), Bradfordia? (Pracoppclia) , and Hcbc-toxyites and is accordingly placed in the lower -S". soivcrbyi Zone, L. discitesSubzone, of the lowermost Bajocian. The Pscudocidoceras zonule includes, be-low, Sonninia (Euhoploccrasj, Eudmctoceras klimakomphalum (Vacek), andDocidoccras s.s. also attesting the L. discites Subzone, and, above, abundantevolute IVitchellia indicating middle to upper S. soivcrhyi Zone.

The Ammonoidea are placed in 15 genera, none new, 13 subgenera withthree new [Sonninia (Alaskoccras) , Docidoccras (Pscudocidoceras) , Brad-fordia} (Pracoppclia)^, 30 species with 13 to 20 new of which nine are named[Partsc/iiccras ellipticum, Pseudolioccras costistriatum, Sonninia (Euhoploceras)bifurcata, S. (Alaskoceras) alaskcnsis, IVitchellia sutneroides, Docidoccras(Pscudocidoceras) luidebaycjisc, D. (P.) camac/ioi, D.? (P.?) paucinodosum,Bradfordia} (Pracoppclia) oppeliiformisli, and tivo subspecies [Pseudolioccrasmaclintocki fastigatum, Eudmctoceras (Euaptctoccras) klimakomphalum dis-coidalc^.

About one-half of the Ammonitina genera and subgenera range higherthan in Europe. Affinities are closest to Europe and secondly to South America;affinities to the Western Pacific (Western Australia and Indonesia) are weakand could be accounted for indirectly by migration via Europe and SouthAmerica. All genera are also known from other continents and only Pseudo-toitcs is restricted to the Pacific. High faunistic diversity and species distribu-tion suggest a somewhat lower latitude or a lower temperature gradient thanat present, or a combination of both factors.

PREFACEThis is the second part of a study of the extraordinarily

rich and well-preserved ammonoid fauna from Wide Bay (former-ly Kialagvik Bay) comprising the almost universal assemblage ofthe Bajocian Sonninia sowerbyi Zone of the Upper Kialagvik For-mation. The first part (Westermann, Bull. Amer. Paleont., vol. 47,No. 216, 1964) dealt with the Erycitoides howelli Zone which wascorrelated with the Lndwigia concava Zone of the Aalenian (for-merly called Lower Bajocian)

.

The great bulk of the E. hoivelli fauna was believed to be en-demic to Alaska and the western Canadian Arctic until recently

Bulletin 255

when Sey and Kaladieva (1967) reported the same fauna from thesoutliern coast of the Okhotsk Sea in far eastern Siberia: lateToarcian sandstone with Pseudoliceras beyrichi (Schloenbach) areoverlain by approximately 480 m siltstones which bear at the baseP. inaclititocki (Haughton) s.s. of early Aalenian age, in the middlepart Erycitoides hozvelli (White) , E. (Kialagvikites) spinatus West-eYn\:inn, Pseudolioceras muclintocki whiteavesi (White) , P. (?) aff.P.m. XL'hiteavesi, and Inoccranius sp., and above luocerarmis sp.and P. (?) aff. P.m. xchitcavesi. These siltstones pass into 370 msandstones and siltstones with Inoceramus sp., followed by UpperJurassic beds with erosional luiconformity. The E. hoxvelli faunahas for the first time permitted the accurate dating of the thickMiddle Jurassic terrigenous sequences distributed throughout east-ern Siberia. Furthermore, Tmetoceros cf. T. flexicostatian Wester-mann has now also been reported from the southern Andes (West-ermann, 1967)

.

Wliile Part 1 of this monograph was in press, the author visit-ed Wide Bay (1 ext-figs. 1,2) in August of 1964 for two weeks dur-ing which 10 days were suitable for field work. Mr. Phillip Hub-bard, then a geology student at Oregon State University, assistedin the field. McMaster University and the National Research Coun-cil of Canada financed this short expedition. All transportationwas by air, with commercial airlines to King Salmon at the easternend of Bristol Bay and small chartered planes expertly piloted bybush pilots, via Pilot Point at Ugashik Bay to Wide Bay makinguse of the intertidal slope at Preston Creek (Camp A) and a smallair strip of former oil exploration at the mouth of Short Creek(Camp B) . After detailed fossil collecting in the S. sowerbyi Zonealong the sea cliffs east of Camp A, a chartered float plane fromPilot Point moved the Camp to location B on the northwestern sideof the bay where the E. Iimvelli Zone of the coastal bluffs fromPass Creek to the head of the bay and the important sections alongShort and Anderson Creeks were re-examined. Important technicaladvice and aid were given by (Charles Rowett, then at the Univer-sity of Alaska, R. L. Dettcrman and T. B. Ball of the U.S. Geo-logical Survey, Alaska Branch, and by M. V. Kirk of Shell OilCompany.

The completion of the second part of this monograph was de-layed because of the necessary re-investigation and taxonomic re-

Alaskan ammonites, Pt. II: Westermann

Scale in Km

Text-fig. 1. Index map of south Alaska.

visions of the northwestern European and South American repre-sentatives of the almost universal S. sowerbyi Zone ammoniteassemblages. Particularly the Hammatoceratidae and Sonniniidaehave been either in a state of utter taxonomic confusion as reflect-ed in the classification of Buckman (1887-1907; 1909-30: NW Eu-rope)

, or are poorly known with regard to range variation andaffinity (South America) . Type specimens were studied in theBritish Museum of Natural History and in the Geological SurveyMuseum, London, with the help of M. K. Howarth and F. M.Anderson; the subgenus Sonninia (Euhoploceras) Buckman wasthoroughly revised (Westermann, 1966) ; the most important classi-cal sections in the southern Andes of Chile and Argentina were re-examined (Westermann, 1967) ; plastotypes of specimens describedin Tornquist's (1898) monograph were kindly sent by H. K.Schmidt, University of Gottingen, and those of Jaworski's (1926)monograph were sent by H. K. Erben, University of Bonn, Ger-many. Of particular interest were the circum-Pacific genus Pseiido-toites Spath and the alleged Australian Zejnistephanus of which

Bl'lleti.x 255

plaster casts ol topotypes were liiriiished by P. }. (Coleman, Uni-versity ol Western Australia, ami by R. \V. Imlay, U.S. GeologicalSurvey. The author also re-examined in 1963 the 5. souwrbyi Zonelocations of Lupher (1911) in east-central Oregon and Crickniay's(1933) Bajocian section at Moiuit [ura. California. Plastotypes ofthe sonniniids from the inaccessible old collecting point at LakeMinewanka in the Alberta foothills (cf. Frebold, 1957a) werefurnished i)y D. McLaren and H. Frebold, Geological Survey ofCanada.

The author owes sincere gratitude to R. \\. Imlay, U.S. Geo-logical Survey, \Vashington, D.C., for making available to him allfossil collections of the Survey from the S. soiverbyi Zone of WideBay and also for fmnishing the plastotypes of all ammonites de-scribed and figined h\ him. The survey collections (USGS) weremade by Walter R. Smith in 1924, S. N. Daviess in 1944, L. B.Kellinn in 1943 and 1915, and R. W. Imlay and Don Miller in1948. A small collection was lent by L. G. Hertlein, of CaliforniaAcademy of Sciences (C.A.S.) in San Francisco, and a few speci-mens were made a\ailai:)le by V. S. Mallory of the Thomas BurkeMemorial \Vashington State Museum, University of Washington(U.W.) in Seattle. M. V. Kirk, Shell Oil Company, who loanedthe entile Aalenian and early Bajocian collections of Wide Bayfor the first part of this monograph, furnished stratigraphic in-formation (cf. Part I) and polaroid photographs of a number ofammonites from the S. soxvcvbyi Zone. However, most imfortini-ately, the entire fossil collection had to he retmned to Shell OilCompany in 1964 after only a preliminary survey of the 5. soxoerbyiassemblages was completed. The taxonomy of the Hammatocera-tidae was fruitfidly (Hscussed with E. Elmi, Universitd' de Lyon,and B. Cieczy, Museinn Koiiit, Budapest.

Mrs. Gay Walker redrew the text-figines and Miss V. Elkingtonmade the prints from films taken by the author.

STRATIGRAPHYUPPER BOUNDARY AND CORRELATION OF THE

KIALAGVIK FORMATION

The difficulties of coirelation and definition of formationalcontacts caused by strong lateral facies changes are enhanced by

Alaskan ammonites, Pt. II: W^estermann

the development ol jxiiiuoiilonnities witli hiati as indicated i)yfossils and by bedding plane taults which are difficult to detect.

In tlie first part of this monograph (Westermann 1964a, text-fig. 4 opp. p. 338) , I adopted the lithostratigraphic correlationand formational boundaries of Shell Oil Company as communicatedby M. V. Kirk, although the alternate position of the formational

contact Kialagvik-Shelikof as placed by the U.S. Geological Sur-

vey had also been indicated. Without direct knowledge of theexposures I chose to reproduce the results based on the more ex-tensive field work which as admitted by R. W. Imlay of the U.S.Geological Sinvey was that carried out by Shell Oil Company.This correlation resulted in a remarkable alleged heterochroneityof the formational contact transgressing along the NW side of WideBay through a lateral distance of only 10 km from tlie top of theE. Iiozoelli Zone (Moose Creek Mt. Kathleen section) to the topof the O. saiizei Zone (Mt. Mamie section) and back to the E.hoxoclli Zone (Short Creek section) involving a stratigraphic in-terval of 200-300 m. Along the southeastern side of the bay, thecontact was placed within the intermediate 5. sowerbyi Zone.

Based on my subsequent brief field work at Wide Bay insimimer, 1964, I now adhere to the definition and correlationof the formational boiuidary as originally implied by Capps(1922) and as amended and defined by Kellum, Daviess, andSwinney in 1944 (1945) , previous to the more recent mappingby Shell Oil Company (luipublished)

.

The base of the Shelikof Formation was originally (Capps,1922) placed at the regional iniconformity (locally a paracon-formity) developed throughout the "Cold Bay" [Puale Bay] areaincluding "Kialagvik Bay" [Wide Bay], of the terrigenous andtuffaceous beds bearing the Callovian guide fossil Cadoceras.

While at Puale Bay the Shelikof lies directly on the LowerJurassic, a thick Middle Jurassic sequence (Aalenian and lowerBajocian) is present at Wide Bay, which Capps (1922) named theKialagvik Formation. However, Capps had only visited the north-west side of tlie bay where the Bajocian (s.s.) is reduced, and heprobably did not see the actual contact which is usually concealed,nor was he able to compile a complete stratigraphic section fromthe isolated exposures {op. cit., p. 95) . The upper expanse of the

10 Bulletin 255

Kialagvik Formation becomes evident from the described ex-posures of "sandstones, sandy shale and conglomerate." Besidesthe E. hoiL'clU Zone of the bluffs, Capps' KialagN ik Formation alsoincluded the O. sauzel Zone of location No. 1-113 (10809), about1 km upstream Caribou Creek at the west end of the bay. Pre-viously T. \V. Stanton (in Capps, 1922, p. 96) noted that theSouniuia and Inoceramus from this locality are "identical withforms in No. 33 of Martin's Tuxedni Bay section" (Martin andKatz, 1912, p. 61: lot No. 33 with "StepJiauoceras, Harpoceras,etc.") [O. sauzei Zone] and are younger than the E. hoicelli as-semblage. This location is probably identical with location F 20of Kellum, et al. (1945, fig. 2) : "Section near Camp 3" which wasplaced in the "Inoceramus sp. C. Subzone." According to Kellum,et al. (loc. cit.) the sandstone bearing this assemblage [O. sauzeiZone] is separated from the "Hatnrnatoceras Zone" [E. howelliZone] beneath by an unconformity and about 125 m of poorlyexposed beds including, above, grey-green silty sandstones withabundant plant fragments. The "Moose Creek - Mt. Kathleen sec-tion" of Shell Oil Company includes Capp's original Kialagviklocation No. 1-113 which, however, is placed in the ShelikofFormation, 100-120 m above the formational contact at the top ofthe E. howelli Zone.

Kellum, et al. (1945), who carried out a summer's field workin 1944 and produced the geological map of Wide Bay, logicallycontinued Capps' preliminary work and successfully attemptedto compile and correlate the three sections of Caribou, Anderson,and Short Creeks. Their placing and correlation of the formationalcontact appears essentially correct and in agreement with the orig-inal definition. In the Anderson Creek section ("Creek near CampNo. 2 ' of Kellum, et ah, "Mt. Mamie section" of Shell Oil Com-j)any)

,the contact was placed similarly by Kelhmi, et al. and Shell

Oil (>ompany, i.e. above the sandstones of the O. sauzei Zone (byShell Oil Company at top of "Seymourites subzone"?) . The al-leged correlation of the E. JioivelU Zone sandstones of CaribouCreek with the O. sauzei Zone sandstones of Anderson Creek asproposed by Shell Oil (Company, appears to be due to the strati-graphic approximation of the respective arenite series in the lattersection; the intermittent argillaceous sequence has become thinner,

Alaskan ammonites, Pt. II: Westermann II

more arenaceous and carbonaceous (Kellum, et al. 1945, fig. 2).Shell location No. A 601 (F43) has been re-examined (WA 14)and is now dated as O. sauzci Zone, based on the presence ofParabigotites crassicostatus Imlay. Shell location No. A 600 (F 42)

,

10-12 m lower in tlie section, is poorly fossiliferous, but a single}Docidoceras (Pseudocidoceras), based on preliminary identificationin 1964, would suggest up to 50-60 m possible 5. soioerbyi Zonein arenaceous-argillaceous and, below, carbonaceous fades.

In the Short Creek section, 5 km northeast of Anderson Creek,only the E. hoivelli Zone is predominantly arenaceous and conglom-eratic. This sequence is overlaid by 30-40 m barren grey shales,well exposed at the steep right bank near the mouth of a tributary.Above follow about 150 m of silty shale with several thick bedsof conglomeratic sandstone and lenticular limestone, the lower50 m of which have now definitely been placed in the O. saiizeiZone [L 1062: Stemjnatoceras cf. S. triptolemus (Morris and Ly-cett) , L 1038: 'Witchellia' adnata Imlay, WA16: Parabigotites sp.];Inoceramus liicifer Eichwald ranges almost to the top of thissequence (F4, F24, F25, WMla) which, therefore, probably belongsentirely in the O. sauzei Zone (cf. Imlay, 1955, p. 86) . This se-quence is conformably overlaid by dark grey shales with diabasesills which have yielded Callovian ammonites at 140-150 m abovebase [A463, F5] and are probably entirely of Callovian age. TheKialagvik-Shelikof contact is, therefore, at the top of the siltyshale and sandstone series of the O. sauzei Zone, as placed byKellum, et al. (1945)

.

The 30-40 m barren shales of the Short Creek section separat-ing the arenite sequences of E. hoxoeUi and O. sauzei Zones may be-long in the S. soiverbyi Zone. These shales can tentatively be cor-related with the poorly exposed argillaceous sequences near thebases of the Caribou Creek and Anderson Creek sections and, per-haps, with the Pseudocidoceras zonule (? and all or part of theoverlying unfossiliferous interbedded shales and sandstones) of thesoutheastern side of the bay.

Along the southeastern shore of Wide Bay, east of PrestonCreek, the bluffs and cliffs expose from the base (1) 10-20 mimfossiliferous mudstone with some greywacke beds, (2) about22 m interbedded silty shale and greywacke grading upwards

12 Bulletin 255

in massive fossiliferous subgreywackc [E. (iniplcc tens zonule of S.sowerbyi Zone]: (3) 50-()() m (? to 100 m) mostly highly fossili-ferous shales with concretions [Pseiidocidoccras zonule of S.sowerbyi Zone] grading upwards into {A) 80-100 m unfossiliferonsinterbedded sandy slialcs and sandstones which are topped by (5)fossiliferous subgreywackes with intermittent silty shale [Parabigo-titcs zonule of O. saiizei Zone]. The E. Jioxi'clli Zone emerges im-mediately west of Preston Creek but crops out below sea leveleastward. Tlie small cape just west of the mouth of Preston Creekwhich forms tlie base of a high bluff (Shell loc. L 154) belongsto tlie T. ten lie zonide, formerly T. tenue-jlexicostatnm zonule oftiie highest E. hoxvelU Zone, lower horizons of which are exposedin the shore cliff at the western end of the Bay (Shell Iocs. L 555,L 556) . However, Shell location L 1 54 in the E. howelli Zone andmy locations ^V^A 3 and WA 4 which yielded the lowest probable5. sowerbyi Zone faunules are stratigraphically separated by about80-100 m unfossiliferons terrigenous sediments, so that the positionof the zonal boiuidary is unknown.

At least most of the bluff west of Preston Creek is roughlyecjuivalent to the bhdfs along the northwestern shore of WideBay, including the base of the Caribou Creek section, while thebluff of the E. amplecten.s zonide east of Preston Creek seems un-represented at the other side of the Ijay.The Pseiidocidoceras zonulemay be c(|ui\alent to the 30-70 m argillaceous beds overlyingthe E. Iioxvelli sandstones at the northwestern side of the bay. TheParabigotites zonule and prol)aljly also at least part of the under-lying interljedded sandstone-shale sequence belong to the "Dnctylio-ceras-Inocerarnus sp. C. Zone" [O. saiizei Zone] of Kellum, et al.(1945) which they believed to be the most persistent zone in theWide Bay area. This forms tlie upper thick arenaceous complex ofthe Kialagvik Formation.

However, Kellum, et nl. (1915, p. 7; diagrammatic section onmap B) wrongly correlated the southeastern shore exposures withthe better known sequence of the other side of Wide Bay. The"sea cliffs . . . from 3i/^ miles from the end of the peninsula . . .all the way to the end of the bay and . . . continuing ... in themountain front beyond to the head of the valley", believed torepresent the "DactyUcoeras-Inocerarniis sp. C. Zone", belong in

Alaskan ammonitks, Pt. II: Westermam 13

the northeast to the lower S. soxverbyi Zone and in the southwestto the upper E. JiowcUi Zone. In their diagrammatic section, theKialagvik-Shelikof contact was drawn at the top of the Pseudocido-ceros zonule but on their geologic map at the top of the E.aniplectens zonule and, soutliwest of Preston Creek, probably nearthe top of the E. howclU Zone.

LOCALITY SYMBOLS

14 Bulletin 255

s

Alaskan ammonites, Pt. II: Westermann 15

NW side of WIDE BAY(Anderson Creek) (Short Creek)

SE side(composite)

// / _(i}7 / Pseudocidoceras zle/ ^'Z-T . Vl.1038.

/

^'V / SOWERBYI /--T^^' /

/ amplectens zleSVLI062

/ZONE

fe^^*'^}^

UPPERHOWELLl ZONE

:)300 MTizJ

Text-fig. 4. Tentative correlations of the upper Kialagvik Formationbetween the Anderson Creek and Short Creek sections at the northwest side(part. Keilum, et al., 1945) and the SE. side (composite) of Wide Bay. Theimportant fossil localities, formational contacts, ammonite zones and zonulesare indicated.

BIOSTRATIGRAPHY OF THE KIALAGVIK FORMATIONERYCITOIDES HOVVELLI ZONE

The results of my brief field work in 1964 (Text-figs. 2-9)are consistent with the faunal sequences as reported from theKialagvik Formation along the northwestern side of Wide Bay inthe first part of this monograph (Westermann, 1964a, p. 339 ff.)

.

The thicknesses of the faunal zonules and their intervals are con-firmed for the Short Creek and Caribou Creek sections except forthe E. howelli zonule which now appears somewhat thicker. How-

16 Bllletin 255

>. -~

CO E-I t,O ^i ^>to en

CO>0"!'ivD J Nvioorva

Ui.

o-

Phylloceras (Zetoceras) cf. P. zetcs (ORB.)Partschiceras ellipiicum sp. n

Holcophylloceras costisparsum IMLAYLytoceras aii. L. eudcsianum (ORB.)Hcbctoxyiics aff. H. hebcs BUCKBradfordia? (Praeoppclia) oppeliiformis subgen. et sp. nPscudolioccras madintocki fastlgatum subsp. nPseudolioccras cost'utriatum sp. n

Asthcnoceras aff. A. nannodes (BUCK.)Eudmctoccras (s.s.) aff. E. cuJmctum BUCKE. (Euaptetoceras) klimakomphalum discoidale subsp. nE. (Euaptetoceras) aff. E. nuctcospinosum WESTE. (Euaptetoceras) amplectens (BUCK) [? Var./subsp. aguilonia IMLAY]Cf. Eudmetoccras s.l.indct. [(J]Planammatoceras (Pscudammatoccrasf) aff. P. benneri (HOFFM.)Sonninia (Euhoploceras) bijurcata sp. nSonninia (Euhoploceras ?) sp. indetSonninia (Alaskoceras) alaskensis subgen. et sp. nIVitchellia sutncroides sp. n

Pclckodites (s.s.) cf. P. pclckus BUCKDocidoceras (s.s.) aff. D. longalvum (VACEK)D, (Pseudocidoceras)

Alaskan ammonites, Pt. II: Westermann

KIALAGVIK FORM

!l 5ill

"

4> -

i \\\

wm

o o

J> >

+ phyllocerasiZeioceras) cf P'es (ORB)

Partschiceras elhpticum sp n

--. Hoicophylioceros costisparsum IMLAY

--- Lytoceros off- L eudesionum (ORB)

Pseudolioceras mchntocki fosiigotum subs

^. P costistriotum sp n

I- Asthenoceras aff. A nannodes (BUCK )

Eudmetoceras aff. E eudmefum BUCK.

^ - ( Euopletoceras ) klimokomphalum dis

17

jidale subsp n

(-? subsp)

() omp/ecfens {BUCK )[var/7 subsp osui/omo IML.]

Sonninia (Euhoploceras) bilurcato sp n

S (E?) sp ndel,

S. lAlaskoceros) alostfensis sp n.

Witcheliia sutneroides sp n

^ -- Pelekodilesct Ppe/ekus BUCK.

R (SpoluMes ?) sp nov off. P spolions

Docidoceras off D longolvum (VACEK)

(Pseudocidoceras) wideboyense sp

(P) cf t*(defcoyense

(P) camachoi sp n

(P)(') sp novB

BUCK.

(R)-'

+ Pseudoloites cf P orjen/mus ARKELL

p cf. P /ronsol/ondcus (TORN )

.- Bradfordio 7 iProeoppelia) oppeliiformis

- Hebetotyites off K hebei BUCK.

Text-fig. 7. Composite section of the S. soiverbyi Zone and ammonitedistribution at the SE. side of Wide Bay. Stratigraphic range of localities(sections) and relative abundances of species indicated.

18 Bulletin 255

Text-fig. 8. Comparison of ihe \ertical ranges of Aalenian and earlyBajocian ammonite genera and subgenera between southern Alaska and north-western Europe. Note the higher ranges of many taxa in southern Alaska.

ever, there is no evidence for the previously inferred thickness in-crease towards the southwest. No adcHtional fossil evidence is avail-aijle for the tentative T. scissum zonule since the basal c. 100 mof the Kialagvik Formation at Short Creek is now almost totallyconcealed. The E. teres zonule (formerly E. teves-projinuhis zon-ule) separating lower and upper E. howclli Zone, is confirmed inthe Short Creek Section (my location WB 5, Kellum, et al., 45 Akni,F12) by abundant Erycitoides teres Westermann, wliich is, there-fore, here named as guide fossil for this assemblage. The T. tenuezonule (formerly tejiue-jlexicostatum zonule) at the top of theE. howelli Zone is confirmed in the same section (my location WB12 = uses 48A - 109) by abundant Tmetoceras tenue Wester-mann, with T. jlexicostatum Westermann and T. cf. kirki Wester-mann; T. tenue is the most distinct species and named guide fossil.Both zonules also bear the zone index E. hozvelli.

SONNINIA SOWERBYI ZONEThe zone contains the E. arn plectens zonule below, and tiie

exceptionally fossiliferous Pseudocidoceras zonide aliove; botli have

been clearly identified only along a 4 km strip at the southeasternshore of the bay.

E. cnnplectens zonule. The zonule consists of 10-12 m mostly

Alaskan ammonites, Pt. II: Westkrmann 19

20 Bulletin 255

massive subgreywacke and yields abundantly Endineloceras (Eu-aptetoceras) arnplecteu.s (Buckman) [incl. var. or subsp. aguilonia(Imlay) ], moderately conmion Docidoceras ? (Psexidocidoceras ?)paucinodosum, n. sp., and scarce cf. D. (P.) xvidebayense, n. sp.,Bradjordia? (Praeoppelia) oppeliiforrnis, n. sp., Hebetoxyites aff.H. hebes Buckman, Sonninia (Eulioploceras}) sp., and phyllocera-tids. This is the "acme-zone" of E. amplcctens, but the speciesranges into the E. howelli Zone below, and into the O. sauzei Zoneabove. The only common species which appears to be restrictedto this zonule is D.} paucinodosum which could, therefore, be con-sidered as guide fossil. The Otoitidae, Oppeliidae, and the strigo-ceratid Hebetoxyites attest to a Lower Bajocian [post-L. concavaZone] age; the common E. amplectens and the stratigraphic posi-tion below the Pscudocidoceras zonule, yielding early Soyininia andDocidoceras s.s., restrict the age correlation to the lower or basalS. soxverbyi Zone, approximately to the (European) Ludxoigiadiscites Subzone.

Although the massive character of the subgreywackes (? andgreywackes) and the apparent random orientation and poor pres-ervation of most ammonite shells suggest submarine slumping orsimilar processes of mass-wasting, there is no paleontological evi-

dence for significant stratigraphic mixing of the faunas. The com-mon Eudmetoccras amplectens are usually strongly corroded, frac-tured, and often fragmented wiiich coidd be due to reworking;alloditliony would be consistent with the known occmrence of thisspecies in the luitlerlying E. hoivelli Zone. The other ammonites,all imknown fiom the Aalenian, are mucli better preserved and,therefore, almost certainly autochthonous. However, even underthe assumption that the E. amplectens are reworked, the E. am-plectens zonule is to be placed in the lower part of the S. sowerbyiZone because of the superimposed Pscudocidoceras zonule.

Pseudocidoceras zonule. The zonule consists of at least 40 m(? to 80 m) shales with calcareous concretions which probablyare separated from the E. amplectens zonule by 10 - 20 m unfossili-ferous shales. This incompetent interval has been structurally re-duced or totally suppressed wherever the competent E. amplectenszonule is exposed and the contact lies below sea level where thesequence appears complete. Thus, all or part of the structurally


isolated 20-30 m shaley section ol locality WA 15 apparently be-longs at the base of tlie Pscudocidoceras zonule. This zonule bearswithout doubt the richest, most diverse and best preserved knownammonite assemblages of the S. sowerbyi Zone in North America,and possibly of anywhere but a few localities of Europe. However,the fossiliferoiis exposmes known in 1964 were restricted to only350 - 400 m length of the shore cliff along the south side of theBay (from loc. WA 10 to loc. WA 15; oW Iocs. 21251 and 12405were concealed or destroyed in 1964)

.

The zonule includes several ammonite assemblages in over-lapping succession. However, horizontal variation being unknown,the apparent famristic changes could be due to differences in bio-facies, post-morte?n drift, and preservation. Nevertheless, the ob-served vertical ranges are probably of more than local significancebecause (1) lithofacies varies little throughout the zonule, (2)ranges vary greatly from species to species with frequent overlaps,and (3) there are certain resemblances in the ammonite succes-sion with other areas.

A two-fold faunistic subdivision of the zonule is strongly ap-parent. The lower part contains abundant Souuinia (Euhoploceras)hijurcata, n. sp., S. (Alaskoceras) aJaskensis, n. subgen. and n. sp.,Docidoceras (Pseudocidoceras) catnachoi, n. subgen. and n. sp., D.(P.) ividebayense, n. sp., Pseudolioceras mackUntocki fastigatunin. subsp., and the less common Brodfordia} (Praeoppelia) oppelii-formis, n. subgen. and n. sp., and Eudtnetoceras (Euaptetoceras)klimakomphalum discoidole, n. subsp.; all are essentially restrict-ed to this part except for D. xvidebayense which ranges throughoutthe zonule. The upper part bears abundant Witchellia siitneroides,n. sp., D. (Pseudocidoceras) xvidebayense, n. sp., and, especially atthe top, moderately common Pseudolioceras costistriatum, n. sp.Other ammonoids such as Phylloceratidae, Lytoceras, Eudmetoceras,Pelekodites, Docidoceras s.s., and Pseudotoites are scarce throughoutthe zonule so that their ranges cannot be established and Astheno-ceras was found only in a "nest," i.e. a single concretion, in themiddle of this interval. A third assemblage may be present at thepoorly known apparent base of the zonule (Iocs. WA 15, ? USGS19801, ? USGS 19863, ? CAS 29011) which yields only a few D.(Pseudocidoceras) and the common S. (Euhoploceras), S. (Alasko-

Bulletin 255

ceras), Pscudolioccxis, and />.? (PracuppcUa). The only other com-mon larger fossils are clusters of Inoceramiis lucifer Eichwakl andfragments of wood and leaflets.

The lower assemblage, for whicli D. (Pseiidocidoceras) cama-choi is chosen as guide fossil, has also furnished near the top asingle Docidoceras aff. 1). lonirfthniin (Vacek) supporting the cor-relation of this interval with the L. disci tes Subzone of the lowerS. sowerbyi Zone. The ujjper assemblage which is probably bestcharacterized by the e\()Iute WitcJicUia sulneroides, sp. n., belongsclearly in ilie liigher part of the S. soxvcrbyi Zone, equivalent toboth or either of the northwest Emopean Subzones of Sonninintrigonolis and WitcJicUia hwxiinsciiJa: IT. sutneroides is indeedmorphologically intermediate between "Zugophorites" Buckman[]\'it( lu'llia subgen.?] of the .S'. trigoualis Subzone and typical]]'it( licllia of the IT', laeviusculn Subzone.

OTOITES SAUZEI ZONE

The ammonoid assemblage of the Parahigotites zonide has re-cently been monographed by Imlay (1964) who has given ampleevidence for O. saiizei Zone. A number of Parahigotites crassico-status Imlay and some Bradfordia sp., Stemmatoceras cf. 5. tripto-lemus (Morris and Lycett) , "Witchellia" adnata Imlay and, sig-nificantly, Eudmetoceras amplectens (Buckman) [var. or subsp.agiiilonia Imlay] have been identified from my localities WA 1,WA 12, WB 1, WB 14, and Shell localities L 1038 and L 1062. TheP. crassicostatus zonule is separated from the Pseiidocidoceras

zonule by 80-100 m unfossiliferous arenaceous shales and sandstones.The beds superposed on the Parahigotites zonule are almost barrenof ammonites, but yield abundant luoceramus lucifer Eichwakl

which appears to Ijecome extinct at ilie top of the O. saiizei Zone(Imlay, 1955, p. 86) . The upper O. saiizei Zone assemblage withSkirroceras kirsclmeri Imlay from southeast Alaska (Imlay, 1964, p.B7) appears to be absent at Wide Bay, probably because beds ofthis age are missing under the paraconformity of the Callovian

Shelikof Formation.


FAUNAL RELATIONS AND AGES OF THE S. SOWERBYIZONE ASSEMBLAGES

The ammonoid fauna of tlie 5. sowerbyi Zone at Wide Bayis in its global relationship essentially European, with an

admixture of Pacific elements and a strong regional (endemic)character at the species level. Tiiis is evident from the followingdiscussion of the principle areas of development of this assemblage,i.e. the North American Cordilleras, the southern Andes, WesternAustralia Indonesia, and Emope. The Phylloceratina, represent-ed by Phylloceras, PartscJiiceras, HolcophyUoceras, and the Lyto-ceratina, represented only hy Lytoceras, are known to be entirelycosmopolitan and, therefore, omitted from this discussion; it ispointed out that their relative al^undance is significantly smallerthan commonly attributed to eugeosynclinal environments, par-ticularly at oceanic margins. Of the 1 1 described Ammonitina gen-era, one appears to be endemic to North America while a numberof the others have here longer vertical ranges than previously

known from other continents, which is essentially the Europeanepeiric Jurassic (Text-fig. 8)

.

NORTH AMERICASoutheast J /fli/ffl. Surprisingly, there is no good evidence for

the presence of the S. sowerbyi Zone in Alaska other than at WideBay, although the Bajocian is well known from the fossiliferousTuxedni Group of Cook Inlet (Imlay, 1962, 1964) where theO. saiizei Zone seems to follow directly on the E. howelli Zone.

However, unfossiliferous beds, which could represent the appar-ently missing zone, are sometimes intercalated in the thick sedi-mentary sequences.

Imlay (1964) described from the Tuxedni Group of the Tal-keetna Mountains several ammonites which are identical with orclosely related to species occurring at Wide Bay in the 5. sowerbyiZone. Sonninia (Euhoploceras) bifnrcata, n. sp. (Imlay, 1964, p.B33, pi. 4, figs. 5, 6, 12; "Sonninia ? n. sp. undet."; p. B14) , whichcould possibly belong in the 5. sowerbyi Zone, and Witchellia sp.were described from the "upper half of the lower sandstone." Theformer species, however, is said to be usually associated withEmileia constricta Imlav, such as in the lowest fossiliferous beds

24 Bulletin 255

of the Red Glacier Formation of the Iniskin Peninsula (op. cit., p.BI4, pi. 4, fig. 10, 11, table 13). E. constricta is a close ally of E.polyshides (^Vaagen) and a good indication of the O. sauzei Zone.S. (Alaskoceras) sp. aff. S. alaskeusis, n. sp. (op. cit., p. B33, pi. 2,fig. 1, 2; "Sonniuio cf. S. nodata Buckman") occurs in the "uppersiltstone" and is said to be associated with Stephanoceras (Skirro-ceras) spp., again clear indicators of the O. sauzei Zone. Eudyneto-ccras (Euaptetoccras) amplectcus (Buckman) [var. or subsp. agiii-lonia (Imlay) ] (op. cit., p. B35, pi. 4, figs. 1-4; 9; pi. 5, figs. 4, 7-9;"Witchellia} aguilonia Imlay, n. sp.") was described from a 60 minterval again yielding the typical O. sauzei Zone assemblage, aswell as from the Parabigoiites zonule of Wide Bay. Planammato-ceras (Pseudainmatoceras?) aff. P. benneri (Hoffman) (op. cit., p.B33, pi. 3, figs. 2-4: "Souuiuia cf. S. patella Waagen") , formerlyknown fiom the L. coticava Zone and L. discites Subzone of Europeand lierc described from_ the 5. soxverbyi Zone of Wide Bay, wasdescribed from the O. sauzei Zone assemblage of the TalkeetnaMountains. However, the alleged Witchellia cf. W. laeviuscula

(J. de C. Sowerby) (Imlay, p. B35, pi. 7) is not a true Witchelliaof the W. laeviuscula gioup.

Western Canada. The S. soxcerbyi Zone is usually absent un-der paraconform O. sauzei Zone or, more frequently, S. humphriesi-aninn Zone. The only known exceptions are probably part of the"middle sedimentary division" of the Hazelton Group of HudsonBay Mountain, west-central British Columbia, and a poorly knownhorizon in the Fernia Group of "Devils Point" at Lake Minne-wanka, Alberta.

The small collection of sorniiniids from scree of Hudson BayMountain was described by McLearn (1926) and dated as O. sauzeito .S'. hutnphriesianutn Zone. However, four of the five new specificnames under Sonniuia and Guhsania McLearn were based on single,incomjilete, and distorted phragmocones only and are here regardedas noniina dubia. Guhsania bella McLearn, the type species, hasa discoidal, almost oxycone shell, with strong rectiradiate simplecostae probably bearing lateral tubercles, and appears to be inter-mediate between Sonninia (Papilliceras) and Fissilobiceras. "Son-ninia Hansoni" resembles the Andean S. espinazitensis Tornquist;".S". skawahi" and ".V. silveria" may belong to a single species of


l:^ W. AUSTRALIA

subgenera

species

Text-fig. 10. Cosmopolitan affinities of the principle ammonite assem-blages of the S. soiverbyi Zone of Wide Bay, possibly indicating migrationroutes; based on numbers of common subgenera and species. Note that the af-finities between southern Alaska and Western Australia Indonesia could beaccounted for by migration via Europe and South America, and that the as-sumption of continental drift would alter the relative position of the Australo-Indonesian area significantly.

Witchellia ("Zugophorites") or possibly partly to Sonninia (Eiiho-ploceras), resembling the species from Lake Minnewanka and evo-lute Witchellia from the middle part of the northwest EuropeanS. soiverbyi Zone. Guhsania bella and "Sonninia Hansoni" couldcome from a higher level, i.e. the O. sauzei Zone. "Guhsania ram-ata" is known from a single small fragment only, resembling G.bella.

The long known poorly preserved small "Devils Point" as-semblage (Whiteaves, 1889) representing the only good evidence

26 Bulletin 255

of the 5. soii'crbyi Zone from (Jan.ula, was redescribed by Frebold(1957a, pp. 48-49, pis. 19-20) and is liere identified with Sonninia(Euhoplocevas/ or Alaskoceras}) gracilis (Whiteaves) , 5. (Euho-ploceros) cf. 5. bifurcata, n. sp. (op. cit., pi. 20, fig. \) , S. (EuJioplo'ceras) sp. (loc. cit., figs. 2, 3) , and Witchellia ("Zugophorites") sp.(op. cit., pi. 19, figs. 2 a, b)

.

Westerji U.S.A. \\\ northern California, the S. sozverbyi Zoneis tentatively indicated in the Mormon Formation of Mount Jura,Shasta County, by (?) Sonnina (Eiilioplorcra.s) "schiiclierti" (Crick-may, 1933, }wm. dub.)

The next best representation of the .S. sowerbyi Zone in NorthAmerica after Wide Bay is in the Supplee area of east-central Ore-gon. The section was described by Lupher (1941) and was re-in-vestigated by Imlay (1964, p. B19) and the author (unpublished),but tlie fossils ha\e not been described. According to Lupher andImlay, the lower part of the A\'^eberg Formation has yielded Tmeto-ccras, ^vhich in its upper range is associated with Praestrigites andDocidoceras; this association, not verified by this author, wouldextend the range of Tinetoceras into the S. soivcrbyi Zone. Abovefollows a rich assemblage of large Sonninia (EiiJioploccras) sp. andIVilclicUia ("ZugopJwrite.s") sp., both strongly reminiscent of theLake Minne^vanka forms but preserved too poorly for specificidentification; this assemblage probably also includes sparse Strigo-ceras, Praestrigites}, Docidoceras s.l., and Eudmetoceras?, thus re-sembling the assemblages of the northwest European lower andmiddle S. sozverbyi Zone. Slightly higher is an assemblage of abun-dant Asthenoceras sp., known in two specimens from the L. murchi-sonae Zone of England and from the S. sozverbyi Zone of Wide Bay,with sparse Witchellia and Sonninia (Euhoploceras). This is fol-lowed by the O. sattzei Zone assemblage of the Warm Springs For-mation which also contains abundant Asthenoceras.

In sunuiiary, the other North American assemblages of theS. sozverbyi Zone have in common with Wide Bay five to sevengenera and at least six subgenera, all of which, however, also oc-cur in Europe; the small number (two to four) of common speciesis probably due to the poor knowledge of the non-Wide Bay as-semblages and specific affinity actually appears to be quite high.Significantly, Bajocian Pseudolioceras and particularly the common


respectively typical Pacific ami Wide Bay forms P.sc'udotoites,'Docidoceras (Pseudocidoccras) and SotDiiiiia (Alaskoceras) appearto be absent while the strigoceraticls, present in the 5. sowerbyi

Zone of Oregon, make their appearance in Alaska only in theO. saiizei Zone. These statements are highly tentative awaiting themonographic study of the Oregon ammonite assemblage. The ap-parent close affinity of the Oregon assemblage, the only betterknown assemblage of the North American S. sowerbyi Zone exceptfor Wide Bay, to the northwest European epeiric seas assemblagesmay be owing to ecological resemblance.

SOUTH AMERICASouther?! Andes. The S. soiverhyi Zone appears to be absent

in the northern and central Andes (Guiana to Peru) , and, contraryto the opinion of Arkell (1954, p. 591; 1956, p. 585) and Imlay

(1964, p. B21) tlie e\'idence for its presence in the soutliern Andesis far from excellent although approximately every second genus,

every fourth subgenus, and probably several species of the WideBay assemblage are found there (Westermann, 1967). In northernChile and northwestern Argentina three major assemblages arepresent, stratigiaphically above early to middle (?upper) Aalenianbeds and below the widespread O. sauzei Zone; they have respec-tively been named after Eudmetoceras (?) gerthi (Jaworski)

,

"Pleydellia" piichensis (Burckardt) , and Pseudotoites singularis(Gottsche) (op. fit.).

The E. gerthi asseml^lage has also yielded Eudmetoceras (?)you'or^A/i Westermann (1964a) ,. (?) kochi (Prinz) , E. (Euapteto-ceras) cf. E. klimakomphalum (Vacek) , E. (E.) klimakomphalummocrickei (Jaworski) [not Bradfordia, with hollow-floored keel]

and probably sparse (?) Sonuiuin (Euhoploceras) sp., Zurcheria (?)sp., "Fontannesia" austroamericnna Jaworski, Tmetoceras cf. T.

scissujn (Benecke) and T. cf. T. flexicostatum Westermann. This

assemblage was dated as upper Aalenian by Jaworski (1926) and

as basal Bajocian L. discites Subzone by Arkell (1956, p. 585) ;either date or both may be correct, and the possibly somewhat

Mm. carlottensis Whiteaves, 1876, from the S. humpricsianum Zone of south-eastern Alaska and coastal British Columbia, is not a Pseudotoites as supposedby Arkell (1954. p. 587; 1956, p. 538, 542) but a Zemistephanus (Imlay, 1964,p. B52).

28 Bulletin 255

condensed assemblage is now placed at about the Aalenian-Bajo-cian boundary.

The "P." puchensis assemblage consists of closely related species(or a "plexus") of late hammatoceratids, possibly intermediateto early sonniniids, described by Burckhardt (1903) imder "Harpo-ceras pucl\cusc, n. sp., H. Jtialarguensc, n. sp., H. hauthali, n. sp.,WitclielUa argcutina, n. sp., Harpoceras striatuliim Sowerby andHarpocerns klirnnkotupluiltun Vacek," as well as of abundantWitchellio}, n. sp. indet. and a single nucleus resembling Sonninia(Fuhoploccras) adicra (W'aagen) . This assemblage is only knownfrom west-central Mendo/a and may be approximately equiva-lent in age to the E. gertlii assemblage.

The P. singularis assemblage overlies the E. gcrthi assemblageand includes the common Pseudotoites (Latotoites) evolutum(Tornquist) , the sparse P. (?) (n. subgen.) spJiaeroceroides (Torn-quist) and probably also P. transatlanticus (Tornquist) , P. argen-tiniis Arkell, Sonninia ("Sonninites") zitteli (Gottsche) , S. intiimes-cens Tornquist and S. (Papilliceras) cf. S. espinazitensis (Torn-quist) . This assemblage belongs, therefore, in the iq^per part of theS. soiverhyi Zone or, possibly, at the base of the O. sanzei Zone.

While the affinity of the E. gerthi assemblage is about equallydivided between southern Alaska and Europe, the P. singularis as-semblage shows additional resemblances to the Australo-Indonesianarea. However, the South American Pseudotoites species are closerto Alaskan than to west Pacific species and have with the formerprobably P. transatlanticus and P. argentinus in common; the An-dean P. singularis is morphologically intermediate between thetypical Australian forms and early Emileia ('Tmileites") of thenorthwestern Euioj^ean middle to upper .S'. sowerbyi Zone. The as-sociated sonniniids Jiaxe affinities with Alaskan and, especially,European species but are unknown from the west Pacific margin.

WEST PACIFIC MARGIN

The only well-known larger assemblage of the S. sowerbyi Zoneis from tiie Newmarracarra Limestone of Western Australia (Arkelland Playford, 1954) ; parts of this assemblage have also been identi-fied from the iMoluccas and New Guinea, but no good evidenceexists for the jjresence of the zone in eastern Asia. The Australian


assemblage has in common with Ahiska three to four genera[Sonninia, Witchellia, Pseudotoites, Docidoceros (?) ] but only oneor possibly two subgenera [the sparse Sonninia (Eitlioploceras) and? Docidocera.s (Trilobiticeras)], and no sjjecies. The assemblage isdominated by the typically European Fontannesia [F. clarkei(Crick) witii syns.] which appears to be absent along the easternPacific margin and by several species of the typically Pacific Pseudo-toites, including the microconchiate P. (Latotoites), some of whichare strongly reminiscent of evolute Emileia s.s. and E. (Otoites)and others of Docidoceras, all of the northwestern EuropeanS. soiverbyi Zone (Westermann, 1964b) . This assemblage also in-cludes sparse "coronate cadicones" which were originally identifiedwith the northwestern American stephanoceratid Zemistephanus(Arkell, in op. cit.) but are in fact closely related to the AndeanPseudotites (?) (n. subgen.) sphaeroceroides (Tornquist) , as wellas a few involute Witchellia.

It appears, therefore, that the relationship of the S. sowerbyiZone Ammonitina assemblages between Australo-Indonesia andAlaska is not so close as previously supposed and that it can beexplained satisfactorily by indirect migratory connections i.e. viathe southeastern Pacific on the one hand and Europe on the other.

EUROPEAll genera of the Alaskan S. soiverbyi Zone, except for the

sparse Pseudotoites, are known from Europe, although Pseudolio-ceras and apparently also the poorly known Asthenoceras are thererestricted to older beds. Of the 12 Ammonitina subgenera (incl.nominate subgen.) known from Alaska, eight were originally de-scribed from northwestern Europe [Eudmetoceras s.s., E. (Euap-tetoceras), Planarnmatoceras (Psendammatoceras), Sonninia (Enho-ploceras), Pelekodites s.s., P. (Spathulites), Docidoceras s.s., D. (Tri-

lobiticeras)'], and of the species at least two or three are in commonwith Europe [Eudmetoceras klimakotnphabtm (Vacek) , E. amplec-tens (Buckman) , ? Pelekodites pelekus (Buckman) ] while fiveothers are very closely affiliated with European species [i.e. to As-thenoceras nannodes (Buckman) , Eudmetoceras eudmetum Buck-man, Planammatoceras benneri (Hoffman) , Docidoceras longal-vum (Vacek), Hebetoxyites hebes Buckman]. Of the other four

30 BlLLETIN 255

Alaskan .sul),


zones of S. soxocrhyi, O. saiizei, and .V. hutnphricsiaiiiini can beidentified with confidence and a subdivision of the S. soiverbyiZone somewhat siniihir to that in Einope is suggested.

Trans-Pacific dispersion of ammonite species chning theBajocian as assumed by Arkell (1956, pp. 597-601) is not a necessaryconclusion from the study of distriijutions, at least not for theNorth Pacific [Zemistcphanus is known only from Alaska andBritish Columbia; Pscvdotoites is rare in North America andthere restricted to southern Alaska] and migration from Australo-Indonesia could have occurred along the continental margin or innarrow marine channels of the Gondwana continent which at thistime was probably beginning to break apart (compare Irwing,1964, figs. 10, 17; Hamilton, 1964, fig. 8).

DIVERSITY AND PALEOLATITUDEBased on the first ammonite monograph by Imlay (1953) and

on several faunal listings, Arkell (1956, p. 617) suggested, that be-cause of high diversity the assemblages of the southern Alaska Juras-sic originated at a lower latitude than their present position(57 - 62N)

.High diversity lias subsequently been confirmed

also for the Aalenian and other Bajocian ammonite assemblages(Imlay, 1961, 1962, 1964; Westermann 1964a) and is here againdemonstrated. The distribution tables of these monographs showthat single ammonite assemblages contain commonly between 10and 20 reasonably abundant species of 6 to 12 genera and threeto six families. Such diversity indicates at least a temperate climatefor the southern Alaska Jurassic seas; cold climate as assumed byBain (1963, fig. 8) can certainly be refuted. Actual diversity countsare not attempted here because they are not available from otherJurassic assemblages. When compared properly with assemblagesequivalent in horizontal and vertical extent, relative abundances,sample size and taxonomic "splitting," the southern AlaskanLower Bajocian ammonite assemblages are closely comparable indiversity to their classical European equivalents. However, otherlarger invertebrates are scarce at Wide Bay except for abundantthin-shelled Inoceramiis which might have been pseudoplanktonic.Typically benthonic bivalves, gastropods, and brachiopods, as wellas belemnites, are extremely rare, w4iile plant remains, particularlyfragmented wooden trunk, are common at several levels.

32 Bulletin 255

Only a few paleomagnetic data are available from NorthAmerica for the position of the Jurassic North Pole and all comefrom tiie southwestern United States; although the plots are widelyscattered even for data from single formations, a mean pole posi-tion lelatively displacing Alaska southward for 8- 12 meridians isindicated (C^oUinson and Runcorn, 1960) . This would shift thelatitude of the southern Alaskan Jurassic from the present 57 - 62N.to aijout 50 N., the present latitudes of northern Oregon andVancou\er Island or of southern England and Central Europe.European latitudes were, however, also appreciably lower than atpresent. Polar shift, possibly comi)ined with warm east Pacific cur-rents as at present, would fully account for temperate Jurassic seasin the area of soutlicrn Alaska. Nevertheless, the prevalence ofterrigenous sediments in contrast to the abimdant limestones in theEuropean Jurassic may suggest relatively higher latitude for south-ern Alaska. Furthermore, low^ thermal gradients of the BajocianPacific Ocean and Atlantic "Ocean" are indicated by the extraordi-nary \\ide distributions of several ammonite species which includeEinope, the southern Andes and southern Alaska. Such reducedgradient could probably be responsible for the recorded diversitywithout change in latitude.

FOSSIL LOCALITIESL'nitcd States Geological Survey (USGS) Mesozoic localities.

(12405 collected by W. R. Smith, 1924; 19028 and 19801 by S. N.Daviess, 1944; 19862-19922 by Lewis B. Kellum, 1945; 21251 and12252 by Ralph W. Imlay and Don J. Miller, 1948)Field Xo. Catalogue Xfo.

F-27 12405 SE. side of Wide Bay, "1.1/2 mi. from capenear islands."

44 A Km F21 19028 [\on F21 of Short Creek section] SE.side of Wide Bay, bluff 1.56 km E. ofPreston Creek, about 11.0 km S. 56 W.of Hartman Isl. Massive sandstone at baseof section.

44 A Km 72 19801 SE. side of Wide Bay, sea cliff c. 1.6 kmE. of Preston Creek, 9.7 km S. 55 W. ofHartman Isl. Base of shaly unit below an

Alaskan ammonites, Pt. II: Wkstkrmann 33

unconformity, shale witli limy concre-tions, Kialagvik Fm.

45 A Km F55 19862 SE. side of Wide Bay, sea cliffs 2.5 km E.of Preslon Creek and 9.0 km S. 52.5 W. ofHarlman Isl., elevation 7 m. Shale withsandstone stringers above massive sand-stone, 43 m below top of Kialagvik Fm.

45 A Km F56 19863 SE. side of Wide Bay, sea cliff about 2.1km E. of Preston Creek and 9.1 km S.53.5 W. of Hartman Isl. (190 m SW. ofuses 19862 "where the shale dips intothe sea") . Float from about 45 m belowtop of Kialagvik Fm., shales with stringersof sandstone.

45 A Km F62 19869 SE. side of Wide Bay, gully near shoreline, about 2.3 km E. of Preston Creek.Interbedded dark grey blocky concretion-ary shale and thin stringers of grey wea-thering limestone, 145 m below top ofKialagvik Fm.

45 A Km F63 19870 Same locality as USGS 19862, but fromtalus at base of sea cliff. Probably fromabout 36 m below top of Kialagvik Fm.

45 A Km F112 19922 8 km SW. of West end of Wide Bay, up-per Kialagvik Creek at SW. foot of LoneHill. About 14 m below top of KialagvikFm.

45 Al 103 21251 SE. side of Wide Bay, sea cliff 8.5 km S.46.5 W. of Hartman Island. (2.85 km E.of Preston Creek). About 150 m belowtop of Kialagvik Fm.

48 Al 104 21252 Same locality as USGS 19862. Gray silt-stone, about 8 m above a massive sand-stone ("probably a little lower than lot21251").

California Academy of Science (CAS) localities109 A 29011 SE. shore of Wide Bay, 5.5 km SW. of

Tatcliff Island. (1.83 km E. of Preston

34 Bulletin 255

Creek) . Black shale "just above contactof Kialagvik witli Shelikof Fm."

C.E.L. No. 68 29014 SE. side of Wide Bay, about 0.3 km W. ofCAS 2901 1 (1.83 km E. of Preston Creek)

.

Dark grey sandstone with basaltic dike,Kialagvik Fm.

Shell Oil Company (Shell) localitiesL 546 SE. shore of Wide Bay, about 2.2 km E.

of Preston Creek, in "Mt. Frances Sec-

tion." About 15 m below top of KialagvikFm. (for localities mentioned in text only,see Text-fig. 2)

.

G. E. G. WcsternKniii (\VA) localitiesField No.W\ 1 SE. side of Wide Bay, 1 .7 km E. of Preston Creek, above

east end of high bluff, elevation 60 to 70 m. Subgrey-wacke and mudstone, some silty shale, 50-65 m strati-grapliically above E. amplectens zonule of bluff; top ofKialagvik Fm. (Plate 2)

.

^VA 2 SE. side of Wide Bay, bluff 1.2 km E. of Preston Creek,elevation c.5 m. 4 m above base of 12 m interbeddedshale, siltstone and greywacke below massive subgrey-wacke of E. aynplectens zonule; Kialagvik Fm. (Plate 3,above, and 4)

.

\\\ 3 SE. side of Wide Bay, subgreywacke bluff 1.6 km E. ofPreston Creek. Float probably from base of bluff; E.amplectens zonule, Kialagvik Fm.

WA 4 SE. side of Wide Bay, bluff 1.65 km E. of Preston Creek,50 m W. of end of subgreywacke bluff. Mudstone, grey-wacke and silty shale about 15 m below top of l)luff[E. amplectens zonide] Kialagvik Fm. (Plate 1).

WA 5 SE. shore of Wide Bay, 1.75 km E. of Preston Creek,more westerly of the two large tectonic blocks of massivesubgreywacke east of main bluffs. From talus of mas-sive subgreywacke and some silty shale; E. aynplectenszonule, Kialagvik Fm.

WA 8 SE. shore of Wide Bay, 1.8 km E. of Preston Creek,


more easterly of the two large tectonic blocks of massivesubgreywacke east of the main bluff with basaltic dike.E. amplectens zonule: about 8 m massive subgreywacke,highly fossiliferous especially at 2.2 to 0.5 m from top;underlain by 3 m mudstone and siltstone, fossiliferousespecially at top and near base; overlain by severalmeters of crumbly shale indicating fault zone (Pseudo-cideras zonule missing) (Plate 3, below)

.

WA 10 SE. shore of Wide Bay, 2.45 to 2.55 km E. of PrestonCreek (4.1 km W. of cape at end of Bay), sea cliff atboth sides of little stream. 21 m dark grey shale withabundant calcareous black concretions, often in beddingplanes and forming a thick "bed" at 10.5 m above baseof section; highly fossiliferous throughout; Pseiidocido-ceras zonule, Kialagvik Fm. (Plate 5)

.

WA 1 1 SE shore of Wide Bay, 2.5 km E. of Preston Creek (50m W. of WA 10) . Kialagvik Fm., from base:30 m dark grey shales with abundant calcareous con-

cretions, especially in lower part, and thick concre-tionary "bed" (same as WA 10, 10.5 m) near base;Pseudocidoceras zonule, highly fossiliferous in lower20 m.

15 m silty and arenaceous shale with few concretions,poorly fossiliferous.

30 m silty shale with interbedded lenticular sandstonebeds, unfossiliferous.

15 m interbedded subgreywacke, sandstone and siltyshale, unfossiliferous.

W^A 12 SE shore of Wide Bay, 2.15 km E. of Preston Creek,elevation about 100 m, top of section beside gully ad-jacent to WA 13 w. 7 m thick-bedded subgreywacke(overlying c.65 m unfossiliferous shales -)- the W^a 15section)

.

WA 13 SE. shore of Wide Bay, 2.48 km E. of Preston Creek(only 15 m W. of WA 1 1 but separated by fault) . About30 m shale with some concretions, fossiliferous at 3 mand 16 m from base; Kialagvik Fm.

WA 13w SE. shore of Wide Bay. 2.45 km E. of Preston Creek

36 Bulletin 255

(15 m \V. of \VA 13). About 20 m shale with singleconcretions, tossiliferous near base; Kialagvik Fm.

^\'A 11 SE. shore of Wide Bay, 1.95 km E. of Preston Creek,low-tide exposure about 30 m from sea cliff. Subgrey-wacke beds; Kialagvik Em.

\\'.\ 15 SE. shore of Wide Bay, 2.15 km E. of Preston Creek.20-30 m shales with some concretions, partly slumpedand faulted; at 3 to 16 m from base moderately fossili-ferous except for abiuidant Itioccraiiius: Kialagvik Fm.

SYSTEMATIC DESCRIPTIONREPOSITORY OF TYPES

Specimens collected by the U.S. Geological Survey, which be-come types by description or figuring, are deposited in the U.S.National Museum (USNM) , Washington, D.C.; specimens collectedby the author are deposited in the Department of Geology at'McMaster University (McM.)

,Hamilton, Ontario, under the

catalogue numbers J . . . . Some fossils are now being returned fromthe U.S. Geological Survey to the California Academy of Sciences(CAS) in San Francisco, California.

MEASUREMENTS OF AMMONOIDSThe measurements taken and their abbreviations are the same

as in the first part of this monograph (Westermann, 1964a, p.357).

Family PHYLLOCERATIDAE Zittel, 1884Subfamily PHYLLOCERATINAE Zittel, 1884

Genus PHYLLOCERAS Suess, 1865Subgenus ZETOCERAS Kovacs, 1939

Phylloceras (Zetoceras) cf. P. zetes (d'Orbigny), 1850PI. 8, fig. 4; Text-fig. 11

Material. A single fragmentary phragmocone with test re-mains came from the Rscudocidoceras zonule, S. sowerbyi Zone, ofWA 10 at 15 m (J 1018).

The specimen closely resembles the phragmocone withcrushed innbilicus recently described by Imlay (1964, p. B31, pi. 2,figs. 3,4) under P/iyllocera.s rf. P. kunthi Neumayr from the O.sauzei Zone of the Tuxedni Formation in the Talkeetna Mountains,


11

Text-fig. 11. Cross-section of Phylloccras (Zftoccras) cf. P. zctcs(d'Orb.), phragmocone fragment, loc. WA IS in the Psrudocidoccras zonule(McM J 1018) ; X 1-

Alaska. Imlay's specimen also has similar irregularly tetraphyllicsaddles (from plastotype) . P. zetes has recently been reinvestigatedby Geczy (1967, p. 9) who concluded that in Hungary Zetocerascannot be separated from PJiylloceras. Zetoceras is, therefore, placedas a subgenus in Phylloceras.

The compressed whorl section with weakly convex, convergingflanks, narrowly rounded venter, umbilical margin and overhang-ing umbilical wall, as well as the rectiradiate lirae and the septalsuture match Geczy's specimen from the Pliensbachian of Hinigary.From Prince Patric Island in the Canadian Arctic, Frebold (1961,p. 5, pis. 7, 8, 9, fig. 2) described the dubious new species P.(Zetoceras) thorsteinssoni which was leased on a single totally septateinternal mold and an undescribed fragment, the only certain differ-ence from P. zetes admittedly being its younger age; possible distinc-tions of the "new species" include a shallow umlDilical slope andmissing radial folds. The Arctic specimens came from the Arkello-ceras beds of the Wilkie Point Formation which probably corres-pond to the O. saiizei Zone, a date based on the occurrenceof Arkelloceras in the O. sauzei Zone of the Alberta foothills(Westermann, 1964b) and Wide Bay (Imlay, 1964, p. B53, pi. 28,figs. 7-9; generic identity here verified) .

38 Jil'I.LETIN 255

fracture

Text-fig. 12. Cross-section of Partschiceras ellipticum, n. sp., incompletephragmocone, loc. WA 8 in the E. amplectens zonule (McM J 962) ; X 1-

Genus PARTSCHICERAS Fucini, 1923

Partschiceras ellipticum Westermann, n. sp. PI. 8, figs. 1,2; Text fig. 12

(?) 1964. Macrophylloccras sp. indet. A, Imlay (SE Alaska), U.S. Geol.Sur., Prof. Pap. 418-B, p. B31, pi. 1, figs. 1-7.

1964. Partschifcras garJanum (Vacek), 1886, subsp. ?, Westermann. (WideBay I) Bull. Amer. Paleont., vol. 47, No. 216, p. 453, pi. 76.

(?) 1964. Partsrhirrras cf. P. gardanum (Vacek), 1886, Westermann, id., p.447, pi. 74, figs. 1-3.

//o/o/)'/?6'. Westermann, lOG-^a, p. 453, pi. 76; well-preservedlarge phragmocone, largely with test, septal suture and innerwhorls exposed. Repository: Cal. Acad. Sci. (San Francisco) 12606.

Locus typinis.-Ca\. Acad. Sci. 29017 (field No. 99): "Cliffexposure on the west shore of the south end of Wide Bay, insidehook made I)y long sand spit."

Stralutu /}'/>/>;/;?/. Kialagvik Formation, upper E. hozvelliZone.

Derivatio notninis. With regard to the elliptical whorl sec-tion.

Diagnosis. An obvolute species of Partschiceras witli com-pressed elliptical whorl section and simple weak costae.

Probable distribution and agc. E. hoivelli Zone to S. humph-riesianum Zone of southern Alaska (Wide Bay, Cook Inlet, andTalkeetna Mountains)

.


Material from the S. sowerbyi Zone. One incomplete phrag-mocone from WA 10 at 2.5 m (J 1013) ; one phragmocone fragmentfrom scree of WA 10 (f 1916) ; one incomplete phragmocone fromWA 8, lower part (} 962) . All internal molds with test remains,E. amplectens and lower Pseudocidoceras zonules of Kialagvik For-mation, Wide Bay.

Description. The whorls are extremely involute to obvoluteand compressed-elliptical in section; the flanks are evenly convexsloping to the occluded umbilicus and to the narrowly curved,somewhat arched venter.

The inner whorls bear slightly prosoradiate^ lirae. At about50 mm diameter, blunt and weak, rectiradiate plications arise onthe outer one-half to two-thirds of the whorl; subsequently, these

simple costae strengthen somewhat, often becoming slightly pro-soradiate, and cross more or less straight over the venter where theyreach their greatest relative strength.

The septal suture has a graded series of slender, essentiallydiphyllic saddles.

Comparison. The holotype from the E. howelli Zone and thespecimens from the S. sowerbyi Zone of Wide Bay match the"Macrophylloceras sp. indet. A" of Imlay (1964, p. B31) from theO. sauzei and 5. humphriesianmn Zones of southeastern Alaska.However, possibly because of imperfect preservation, the "vague

flexuous undulations" on the innermost whorls of the Cook Inletspecies (loc. cit.) cannot be seen on the Wide Bay specimens.

This species appears closely related to Partschiceras grossico-statum (Imlay, 1953, p. 74, pi. 25) from the Callovian of south-eastern Alaska which is distinguished in the extremely dense sec-ondary costation, especially on the venter where the primary cos-tae become obsolete. Significantly, a specimen morphologically ex-actly intermediate between the Lower Bajocian and CallovianAlaskan species has been described by Imlay (1962, p. A5) fromthe early Upper Bajocian Magasphaeroceras rotimdum assemblageof the Tuxedni Formation, Cook Inlet; while coiling and whorlsection are the same as in P. ellipticum and P. grossicostation, thecostation is intermediate consisting of continuous primaries anti

Correct spelling for "prorsiradiate" auct., according to Classics Dept., Mc-Master University.

40 Bulletin 255

relatively strong short secondaries singly intercalated on the venter.All other Partsc/iiccras species (including the synonym Macro-

phylloccras Spath, 1927) are distinguished by the subrectangularto subsquare whorl section and stronger costation or stronger cos-tation. Some resemblance can be seen to P. gardaninn (Vacek, 1886,p. 70, pi. 6, figs. 1-3) from the partly condensed Aalenian to basalBajocian beds of Cap S. Vigilio in the Alps which is distinguishedby the development of an umbilical edge.

The Alaska species agrees in the wiiorl sha}}e and coiling withPhylloceras hctcrophyllum (J. Sowerby) , type species of Pliyllo-ceros.

Measurements. Dmm W% H%holotype (phragm.).


Material. One internal mold of a damaged j)hragmocone andone incomplete body chamber from USGS 21252; one well-preservedincomplete phragmocone with exposed inner whorls and one frag-ment, from USGS 19862 (USNM 160921); one incomplete bodychamber with shell remains from scree of WA 5 (J 1012) ; (?) onecrushed fragment from WA 10 at 22 m (J 1008) ; one internal moldof a phragmocone fragment with incomplete body chamber, ? onejuvenile or nucleus from scree of WA 13 w (} 1011). From tliePseudocidoceras and E. aniplectens zonides of the S. soiverbyi Zone,Kialagvik Formation, Wide Bay.

Description. The whorls are strongly involute to obvolutewith moderately compressed elliptical, often somewhat ovate sec-tion becoming more or less strongly subrectangular towards theend of the phragmocone. There are five to seven sigmoid constric-tions per whorl, distally only slightly projecting, sometimes recti-radiate and usually crossing the venter with slight convexity orvery obtuse arch. The internal mold is almost smooth except forsome barely visible, somewhat falcoid plications on the body cham-ber which become irregidar and obscure on the middle and innerflank. The septal suture has a graded sequence of slender diphyllicsaddles.

Disciissio7i. There is perfect resemblance with H. costispar-sum Imlay from the O. saitzei, S. humphriesiannm, and S. suhjur-catinti Zones of the Cook Inlet region, southeastern Alaska, ex-tending the range of this species throughout most of the Bajocian(s.s.). There can be little doubt that the early Upper Bajocian"Calliphylloceras sp." of Imlay (1962, p. A5, pi. 1, fig. 8) is identi-cal with H. costisparsiini in which the constrictions are also atleast in part restricted to the internal mold (cf. Imlay, 1964, pi. 1,fig. 15) indicating the insignificance of this feature for the dis-

tinction of Calliphylloceras from Holcophylloceras.Holcophylloceras cf. H. ultramontanum (Zittel) from the sub-

jacent E. hoivelli Zone of Wide Bay (Westermann, 1964a, p. 448, pi.74, figs. 4-7) is distinguished only by the falcoid and strongly pro-jected constrictions which on the externside are strongly convexor arched comprising almost a right angle.

H. costisparsnrn is morphologically and stratigraphically inter-mediate between H. ultramontanum (Zittel, 1869, p. 66, pi. 1, figs.

42 Bulletin 255

4-6) , ranging throughout the Aalenian (-J-? S. soxverbyi Zone) , andH. mediterraneum (Neumayr, 1871, p. 340, pi. 17, figs. 2-5) [= H.zignodianutn d'Orbigny, 1848, pi. 182] which ranges from the Up-per Bajocian to the Tithonian (Wendt, 1963, p. 115). H. ultra-Tnontanum is distinguished by fewer constrictions of falcoid shape,or bearing lateral "tongues," and by more compressed whorls; H.tncditerraneuni has a larger umbilicus and stronger costation. InA. costisparsum the constrictions are essentially restricted to the

internal mokl tlius resembling CalUphylloceras. Another interme-diary is the dubious H. deslongchainpsi (Brasil, 1895, p. 29, pi. 1,figs. 6-8) , known only in a few inner whorls from the S. humphrie-sianum Zone of Sully in Normandy, which, reversely appears to re-semble H. ultrnrnoritanuni in whorl shape and coiling, but H.mediteiTaneiiin in tlie constrictions. The taxonomic significanceof the shallow linguate depressions projecting mid-laterally fromthe constrictions is doubtful since they have been observed seem-ingly irregularly in a number of species (cf. d'Orbigny, 1848, pi.182, fig. 3).

Measurements.

Dmm W% H% U%USNM 160921 (phragm.) (C.70)

Alaskan ammoxNites, Pt. II: Westermann 43

Text-fig. 14. Cross-section of Lyto-ceras sp. aff. L. eudesianum (d'Orb.), in-complete phragmocone, loc. WA 10 in thePseudocidoceras zonule (McM J 1005) ;X 1.

The shell is planulate with advolute circular whorls. The in-ternal mold is usually smooth, except for markings of "rhythmic"growth on a single small phragmocone (J 1010) . The test bearsrectiradiate sometimes slightly flexed lirae or riblets of somewhatuneven strength, every third or fourth of which is finely crinkled(festooned) at least on the outer whorls. The septal suture hasrelatively simple and regular saddle endings.

This species matches D'Orbigny's figure of the holotype (1846,pi. 128) except for the missing lamellar flares. Because of the muchfiner crenulation, it is unlikely that the intermittent and somewhatraised crinkled lirae or riblets are the remnants of dissolved flares.L. neumayri Pugin (1964, p. 34, pi. 2, figs. 2-3) is distinguished bysmooth lirae or riblets and the absence of flares. L. espinazitumPugin (1964, p. 32; for "L. eudesianum" of Gottsche, 1878, p. 8,pi. 1, fig. 1) is distinguished by regular constrictions. However,

44 Bulletin 255

Imlay (1961. p. B32) who recently described but did not figurethe first probable L. rudcsiamirn from the O. sanzci Zone of south-eastern Alaska, mentioned "weak constrictions." Lytoceras eiidesi-anutn has previously been known to range from the S. humphriesi-amnij Zone to the Lower Callovian of Europe only (Pugin, 1964,p. 32; Sturani, 1964b, p. 12; VVendt, 1964, p. 116). AVhile LowerJurassic Lytoceras species persist into the Aalenian where they be-come increasingly rare, the genus is almost luiknown from theLower Bajocian S. sowerbyi and O. sauzei Zones. Besides the rareL. espinazittiw mentioned above, there is L. siibfrancisci Sturani(1964b, p. 13; synonym "L. vaccki" Geczy, 1964 z=: L. francisciVacek, 1886, pi. 2, non Oppel) with a range from the Aalenian tothe S. Innnphric.siauiun Zone, which is distinguished by the com-pressed elliptical whorls (and spiralic lirae) and said to be inter-mediate between the Toarcian L. francisci and L. eudesiauum. S.siibfrancisci has intermittent crinkled riblets or lirae on the innerwhorls and lirae with intermittent blimt riblets on the outer whorls,witliout flares. The Alaskan species is, therefore, morphologicallyintei mediate between /.. subfraticisci Sturani and L. eudcsianum(d'Orb.) .

Measurements.

Dmm W% H% U%J1005 (phragm.)

JIOIO (phragm.)

94


Text-fig. 15a-b. Cross-sections ofHcbetoxyitrs sp. aff. H. hebes Buckman,microconchs from the E. amplcctens zon-ule; X 1- a- Complete specimen with lap-pet, loc. WA 5 (McM J 1043). b. Incom-plete specimen, loc. WA 8 (McM J 1041).

tiire, and a few poorly preserved fragments including body chamberimprint with lappet, from the upper part of WA 8 and scree ofWA 5. All from the E. atnplectens zonule of the S. sowerbyi Zone,Kialagvik Formation, Wide Bay.

Description. Tlie phragmocone is typically oxycone with in-volute compressed whorls, converging outer flanks and narrowlyrounded venter. Tiie inner flanks are parallel up to the sharp um-bilical margin on the complete specimen (J 1043) , but markedlyconvex beside the raised umbilical edge at the other specimen (J1041), causing a sliglit rise of the flanks at about two-fifths whorlheight. The phragmocone measures only 20-30 mm in diameter.The body chamber, only about three-fifths whorls long, becomesinflated and assumes "elliptical" coiling, with the umbilical seamegiessing almost radially and finally returning to spiral coiling;whorl height is reduced while the venter becomes more broadlyrounded. The aperture has a slightly projected broad ventral lipand prominent mid-lateral lappets with thickened test. Both pre-served lappets (left lappet of J 1043 and right imprint from same)are incomplete consisting of narrow tongue-like projections. Thecomplete shell diameter varies between approximately 30 and 45mm.

The costation is obsolete on the complete specimen (J 1043)except for faint rursiradiate plication visible under oblique illumi-nation on the outer flanks of the body chamber. The somewhatsmaller incomplete specimen (J 1041) bears, on the whole ultimatewhorl somewhat falcoid rursiradiate blunt costae or plications

46 Bulletin 255

which become obsolete on the mid-lateral spiral rise. The innerconvex part of tlie flank is smootli. Tlie plications die out graduallybeside tlie venter.

The septal suture is only moderately complex, even consider-ing the small si/e. E is well developed and as deep as L, the E/L andL/U saddles are of similar si/.e; these imibilical elements form agraded series with rectiradiate "satldle line".

Discussion. While this is the first description of Hebetoxyitesfrom the Americas, supposed H. cf. hcbcs and H. cf. clypeus Buck-man have i)een recorded by Lupher (1941) from the upper S.sowerbyi or O. sauzci Zone of east-central Oregon.

The whoil shape and coiling of the phragmocone and theseptal suture are good evidence that this is a strigoceratid closelyaffiliated witli Hebetoxyites. A literature survey indicates that speci-mens with complete body chambers are exceedingly rare in theStrigoceratidae. The fact that small specimens with incompletebody chambers which may include microconchs as well as im-matures, have rarely been figured, may be due to the difficulty ofidentifying small strigoceratids since many of the diagnostic featuresare developed only in the adult macroconchiate phragmocone ormicroconchiate body chamber. The body chamber of these micro-conchs, measuring barely one-half the size of figured macroconchs,deviates from the described macroconchiate strigoceratids in theegression of the umbilical seam, i.e. "elliptical coiling". This is awell-known and common microconchiate feature in other families.Nevertheless, affinity of the Wide Bay microconchiate phragmoconesis close to the macroconchiate H. hebes Buckman. Consecjuently,the author does not hesitate to place these specimens in Hebetoxy-ites and, furthermore, sees no necessity to create a new "mono-

sexual" subgenus for these probable male shells.There is also some resemblance to the larger umbilicate and

less discoidal Bradjordia; this is considered of phylogenetic signifi-cance suggesting common ancestors.

Measurements.

Dmm W% H% U%J1043 (apert.)

(phragm.)J1041 (phragm.)

43


Family OPPELIIDAE Bonarelli, 1894

Subfamily OPPELIINAE Bonarelli, 1894

Bradfordia and Oppelia. The genus Oppelia Waagen, 1869[type species Ammonites subradiatus J. de C. Sowerby; holotype re-figured in Arkell, 1951, p. 51] was defined in the Treatise (Arkell,et al., 1957, p. L 275) as "compressed, involute, feebly keeled; withdistant falcoid primary ribbing and close fine secondaries on ven-trolateral edge". In contrast, Bradfordia Buckman, 1910 [typespecies B. liomphala Buckman, 1910] was defined (loc. cit.) ascomprising the "group of Oppelia praeradiata H. Douville; moder-ately involute to involute, imkeeled, venter rounded, smooth, um-bilical wall steep, umbilical edge sharp or raised; outer half ofwhorl sides with fine, somewhat rursiradiate ribbing which is notprojected on shoulders. Sutures simple for the family". The allegedoccurrence of Bradfordia in Argentina was based on the erroneousidentification of Eudmetoceras (Euaptetoceras) klimakomplialuynmoerickei (Jaworski, 1926) . However, as most recently pointed outby Geczy (1967, p. 224) Bradfordia is difficult to define and theTreatise diagnosis as quoted above is unsatisfactory especially withregard to the costation. In contrast to the Treatise, the originalauthor (Buckman, 1910, p. 95) excluded O. praeradiata from thegenus because of the slightly projected and truncated costae. Fur-thermore, only a year prior to the Treatise, Arkell (1956, p. 166)placed in Bradfordia three species with strongly projected costae,i.e. 'Oppelia' gracililobata Vacek, 'O.' subplica tella Vacek, and'Harpoceras' bluynius de Gregorio [syn. O. platyomphala Vacek].The first two species differ also in the differentiation of the costaewhich closely resemble those of Oppelia s. s. The raised umbilicaledge of these species is not a diagnostic feature for Bradfordia, be-cause it is missing in the type species.

The septal suture of Bradfordia is less complex, with smallerE, broader L, and fewer umbilical elements than in Oppelia. How-ever, the dubious "Amblyoxyites" Buckman, 1922, which closelyresembles involute Bradfordia and is usually placed in tentativesynonymy, has the suture of Oppelia.

The Mediterranean 'O.' gracililobata^ 'O.' subplicatella andeven more so the Alaskan B-f oppeliiformis, n. sp., combine fea-

48 Bulletin 255

tares ot Bradfordia wiili iliose ol Oppcliii; the sole distinction ot theWide Bay species from Oppclia s. s. is in the narrowly roundedventer and probaljly also in the septal siitine which actually appearsintermediate between Bradfordia and Oppelia. According to thenumi)er of characters-in-conimon this species group should prob-ably I)e classified with Oppelia, but the application of the con-ventional positive weighing of ventral featines woidd place it inBradfordia. This species group is, therefore, classified as new sub-genus Pracoppclia and tentati\cly placed in Bradfordia.

Genus BRADFORDIA Buckman, 1910Subgenus BRADFORDIA ? (PRAEOPPELIA) Westermann, n. subgen.

Type species. B.^ (P.) opprliiforniis, n. sp.Subgenus diagnosis. Ldv^e, strongly compressed, involute,

venter rounded; with distant falcoid primaries and short denseprojected secondaries fading out ventrally or forming blunt chev-rons; resembling Oppelia s. s. except for the venter (and the lessdeveloped septal suture)

.

Rer/iarks. The subgenus probably includes 'O.' gracililobataV^acek of which the inner whorls are poorly known [the innerwhorls figured by Vacek, 1886, pi. 10, figs. 2, 3. are not conspecific;

fide Ceczy, 1967, p. 225] and "O." subplicatella Vacek, a possiblesynonym. However, both appear to differ in tlie septal sutme withless developed E lobes and E/L saddles. All are from the (lower)S. soxeerbyi Zone.

Bradfordia? (Praeoppeiia) oppeliiformis Westermann, n. sp.PI. 10, figs. 3-6; Pis. 11, 12; Text-figs. 16a-b

Holotype. PI. 10, fig. 6; PI. 20; well-preserved complete phrag-mocone with incomplete crushed body chamber. Repository: USNM160922.

Locus typicus. U.S. Geological Survey Mesozoic locality19863 [= 45 AKm F56 (float), coll. L. B. Kellum, 1945], sea cliffon the southeastern side of Wide Bay.

Stratum typiciun. ShAes of the upper Kialagvik Formation,probably in or subjacent to the basal Pseudocidoceras zonule, S.soiverbyi Zone; associated with Eudmetoceras klimakomphahimdiscoidale, n. subsp., and Docidoceras camachoi, n. sp.


K

Text-fig. 16 a-b Bradford'ia? (Pracoppdia) opprliiformis, n. sp. a.Cross-section of phragmocone, loc. USGS 21252 in the Pscudocidoceras zonule(USNM 160923)

; X 1- b. External septal suture, loc. UW WA-11, lot 37 (UW13180) ; X 1.5.

Derivatio noiniuis. Reflecting the close affinity to Oppelias.s.

Age. (Lower) .S'. soioerbyi Zone.Diagnosis. A species of D.f (Praeoppelia) with strongly com-

pressed inner whorls, outer whorls compressed subelliptical withinner flanks sloping gently towards the somewhat rounded notmarkedly raised umbilical margin.

Material. The holotype and three somewhat crushed incom-plete internal molds from USGS 19863; one partly crushed internalmold from USGS 19862; one large phragmocone and one crushedjuvenile or inner whorl from CAS 29011; one well-preserved phrag-mocone with preserved nucleus and test from USGS 21252 (USNM160923) ; one large phragmocone with well-preserved septal suturefrom UW WA-111, lot 37 (UW 13180); one slightly crushedphragmocone, internal mold, from WA 15 at 3 m (J 1039) ; oneincomplete phragmocone with preserved nucleus from scree ofWA 5 (J 1040) . All from the upper Kialagvik Formation, probably

50 Bulletin 255

E. atnplcctois to basal Pseudocidoceras zonules of the lower S.soiverbyi Zone, Kialagvik Formation, Wide Bay.

Description. The nucleus at 12-15 mm diameter consists ofsmooth, moderately involute, strongly compressed elliptical whorlswith shallow umbilicus, the convex sides sloping gently to the um-bilical seam. Subsecpiently, a narrow umbilical wall with somewhatrounded margin develops, the whorls become involute, the innerflanks flatten but continue to slope toward the umbilicus so that thegreatest whorl width is retained mid-laterally, and the typicalcostation develops. The immature costation consists of blunt some-what irregular falcate primaries which are mainly superficial butbecome stronger on the outer one-third of the flank, and of shortblunt strongly prosocline secondaries on the rounded shoulderswhicli are singly and in pairs intercalated and cross weakly overthe venter.

The matme phragmocone retains the strongly compressed in-volute wliorls with convex flanks. However, the umbilicus deepenssomewhat, due to the slightly raised rounded umbilical margin andthe conesponding development of a shallow depression on tlielowermost flanks; the whorls remain thickest at or just above themiddle of the flanks. The outer flanks converge gently, often mark-edly flattened, towards the evenly and narrowly roimded venterwhich may widen somewhat towards the end of the phragmocone.The mature costation consists of somewhat irregular, more or lessstrongly concave (distally j^rojected) primaries on the outer half ofthe flank, a few of them continuing faintly onto the inner flanksforming weakly falcate to falcoid costae, and of nimierous proso-radiate short secondaries on the shoidders which become mediallyobsolete or cross the venter convexly cmved or arcuate. The pri-maries are sometimes obscurely bundled in pairs at about two-thirdswhorl lieight, and the secondaries are born about as often by anas-tomosis, bifurcation of primaries or intercalation. At the end oflarge phragmocones, both primaries and secondaries weaken if thelatter do not become obsolete.

The complete phragmocone measures approximately 120 mmin diameter. The body chamber is known only from the holotypewhere it is incomplete (one-half whorl) . Tlie full diameter is esti-


mated at 160 mm. Tlie umbilicus remains narrow and shallow witlithe umbilical wall rounding into the whorl sides; tlie externside isbroadly rounded. The body chamber is almost smooth except forsomewhat irregular more or less rectiradiaie plications on the outerflanks.

The septal suture is moderately complex (Text-fig. 166) . E islarge and only slightly sliorter than L; L is broad and trifid withshort thick stems; the L/U saddle is at least as wide and high as E/L;the umbilical lobes terminate at a common radius with L; Uo isabout half as broad as L and the broad Uo/Ug saddle about two-thirds as large as L/U2 (2d and 3d morph. lat.) ; the other um-bilical elements are much smaller with only the outer saddle fullydeveloped bearing first and second-order frilling. The suture is,therefore, intermediate in character between Bradfordia (s. s.) andOppelia with respect to the size of E and the number of major um-bilical elements.

Discussion. This new species is most closely related to'Oppelia' suhplicatella and 'O.' gracililobata, Vacek spp., of theMediterranean lower .S'. sowerbyi Zone, but distinguished by tliemore involute and compressed inner whorls, the depressed and lessdeveloped circum-umbilical area and, probably, the larger E lobe.

There are also some striking resemblances to the internal molds(without the hollow-floored keel) of Eudmetoceras (Euaptetoceras)amplectens (Buckman) and to a lesser degree also to E. (E.) klijna-komphalum discoidale, n. subsp., both of which are associated.

The phylogenetic origin of the Oppeliidae arising with Brad-fordia from Eudmetoceras lias repeatedly been suggested (Arkellet al., 1957, p. L 275; Geczy, 1967, p. 225) and the Alaskan evidencefavours this hypothesis if PraeoppeUa is included in Bradfordia. Ofspecial interest is the regional morphological "habitus" of theevolving lineages giving rise to the vexing problem of possible poly-phyly or ecotypes: the Alaskan E. amplecferis, E. klimakomphalum

,

and B? oppeliiformis are all distinguished from their Mediterraneancounterparts in the

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Bulletins of American Paleontology Vol. LVII