Upper Jurassic 

Mollusks from 

Eastern Oregon and 

Western Idaho

GEOLOGICAL SURVEY PROFESSIONAL PAPER 483-D

Upper Jurassic 

Mollusks from 

Eastern Oregon and 

Western Idaho

By RALPH W. IMLAY

CONTRIBUTIONS TO PALEONTOLOGY

GEOLOGICAL SURVEY PROFESSIONAL PAPER 483-D

Faunal evidence for the presence of Upper 

Jurassic sedimentary rocks in eastern Oregon 

and westernmost Idaho

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1964
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U.S. Government Printing Office

Washington, D.C. 20402
CONTENTS

Abstract.__________________________________________

Introduction.______________________________________

Biologic analysis..._________________________________

Stratigraphic summary._____________________________

Northeastern Oregon and adjoining Idaho. ________

Mineral area, western Idaho.____________________

East-central Oregon_____________________________

Conditions of deposition.____________________________

Ages and correlations______________________________

Unnamed beds in northeastern Oregon and adjoining 

Idaho_______________________________________

Unnamed beds near Mineral, Idaho.______________

Snowshoe Formation of Lupher, 1941, in east-central 

Oregon._____________________________________

Dl

1

2

2

2

2

4

6

6

Page 

Ages and correlations Continued

Trowbridge Formation of Lupher, 1941, in eastcentral Oregon.__________---_-_-__-_-____---_ D9

Lonesome Formation of Lupher, 1941, in east-central

Oregon..________________-_--_____--_--_---__ 9

Comparisons with other faunas.______________________ 10

Alaska and western British Columbia-____________ 10

Calif ornia. ... _ __-_________--____-___-__---___-_ 10

Western interior of North America._______________ 10

Geographic distribution________-_-_____---_---_-.__ 11

Systematic descriptions..._--_--__-__________________ 13

Literature cited_____-__-_____---------_-_--_--__-___ 17

Index_.______________--____---------_-__---_-_-___ 21

ILLUSTRATIONS

[Plates 1-4 follow index]

PLATE 1. Gryphaea, Posidonia, and Xenocephalites.

2. Cardioceras (Scarburgiceras~), Pseudocadocerast, and Lilloettia.

3. Kepplerites (Gowericeras) and Choffatia (Loboplanulites').

4. Parareineckeia and Cobbanites.

FIGURE 1. Index map showing Upper Jurassic fossil locality in west-central Idaho-_

2. Index map showing Upper Jurassic fossil localities near Mineral (abandoned) , Idaho._-__________________--__--____---___-_----__----_

3. Index map showing Upper Jurassic fossil localities near Izee in eastcentral Oregon._____-____-________-__________--__--___-___-----

D3

4

5

TABLES

TABLE 1. Ammonite genera and subgenera from beds of Late Jurassic age in eastern

Oregon and western Idaho.______________________________________ D2

2. Geographic distribution of Upper Jurassic mollusks in east-central

Oregon and western Idaho.___________-_________-__----_-_------- 7

in

CONTRIBUTIONS TO PALEONTOLOGY

UPPER JURASSIC MOLLUSKS FROM EASTERN OREGON AND WESTERN IDAHO

By RALPH W. IMLAY

ABSTRACT

Jurassic ammonites of early Callovian age occur throughout 

more than 13,000 feet of strata exposed along and near the South. 

Fork of the John Day River near Izee in east-central Oregon. 

They occur also in several hundred feet of dark shale exposed 

along Dennett Creek near Mineral, Idaho. Other ammonites of 

early Oxfordian age were found in Idaho about 400 feet above 

the base of 1,000 feet of tough noncalcareous black shale exposed 

in the canyon of the Snake River near the northeast corner of 

Oregon and the southeast corner of Washington. These 

Oxfordian ammonites were collected in Idaho about one-third 

of a mile east of the Snake River. The black shale in which they 

occur is well exposed on the Oregon side of the canyon.

The early Callovian is represented by the ammonites Xenocephalites, Lilloettia, Kepplerites (Gowericeras}, Parareineckeia, 

Cobbanites, Pseudocadoceras?, and Choffatia. All these except 

Pseudocadocerasl occur in the upper part of the Snowshoe Formation of Lupher (1941) near Izee in east-central Oregon and are 

excellent evidence for the age of the upper part of that formation. 

The first three ammonites listed are not known below the 

Callovian and the next two listed are not known above the lower 

Callovian.

The middle and lower middle parts of the overlying Trowbridge 

Formation of Lupher (1941) contain the ammonites Xenocephalites'!, Lilloettia, and Kepplerites (Gowericeras) of early to early 

middle Callovian age. The species present occur in beds of 

early Callovian age in British Columbia and Alaska. An early 

Callovian age is confirmed by the ammonite genera present in 

the overlying Lonesome Formation of Lupher (1941).

The overlying Lonesome Formation has furnished Xenocephalites and fragments probably belonging to that genus throughout 

most of its great thickness. It is, therefore, probably entirely 

of early Callovian age. This age is confirmed locally by the 

association of Xenocephalites with Cobbanites and Lilloettia. 

The presence of Pseudocadoceras? in two places is not evidence 

of a younger age as the genus in Europe ranges from the upper 

lower Callovian to near the top of the stage.

Several hundred feet of dark shale near Mineral, Idaho, 

contains the ammonites Xenocephalites, Lilloettia, and Cobbanites 

of early Callovian age. The species present are identical with 

species in the Trowbridge and Snowshoe Formations of eastcentral Oregon.

The early Oxfordian is represented by the ammonite Cardioceras obtained from black shale exposed on the Idaho side of the 

Snake River Canyon near the northeast corner of Oregon. 

This is the first faunal evidence for rocks of that particular age 

on the Pacific coast south of British Columbia.

The Upper Jurassic (Callovian and Oxfordian) ammonites 

from east-central Oregon and westernmost Idaho are identical 

or closely comparable to species in western British Columbia and 

Alaska. Assemblages of the same age in the western interior of 

North America differ considerably in generic composition and do 

not appear to have any species in common. Some faunal 

resemblances exist with ammonites of early Callovian age in 

California. Comparisons are difficult, however, because in 

California few ammonites of early Callovian age have been 

described and none of early Oxfordian age has been recognized.

INTRODUCTION

The ammonites described herein have been studied in 

order to demonstrate the existence of thick sequences of 

early Late Jurassic strata in eastern Oregon and western 

Idaho. Proof that more than 13,000 feet of strata were 

deposited in eastern Oregon during only part of the 

Callovian stage should interest geologists concerned 

with sedimentation and tectonics. The close affinities 

of the ammonites with those of the same age in western 

British Columbia and Alaska should interest geologists 

concerned with paleogeography. In particular the 

presence of the boreal ammonite Cardioceras in shale in 

the Snake River Canyon near the northeast corner of 

Oregon suggests that the sea in which it lived extended 

across the area of the state of Washington.

The fossils were collected by R. L. Lupher in 1930 and 

1937, D. C. Livingston prior to 1932, W. R. Wagner in 

1945, S. W. Muller in 1956, L. W. Vigrass in 1956, John 

Beeson in 1956 and 1957, R. W. Imlay in 1956-58 and 

1962, W. R. Dickinson in 1957, Reed Christner in 1958, 

Marvin Beeson in 1959-61, Richard Bateman in 1961, 

Howard Brooks in 1962, and R. F. Morrison in 1961 

and 1962.

Correlation charts of the Upper Jurassic formations 

and faunas of the Pacific coast region have been published previously (Imlay, 1961, figs. 1 and 2 on p. D4- 

D5) and are not repeated herein.

Dl
D2 CONTRIBUTIONS TO PALEONTOLOGY

BIOLOGIC ANALYSIS

The Upper Jurassic ammonites from east-central 

Oregon and western Idaho described herein include 

about 175 specimens of which 90 specimens are too 

poorly preserved for generic identification. Their biologic distribution from subgenus to family is shown in 

table 1. This table shows that the Macrocephalitidae 

is by far the dominant family. The Cardioceratidae, 

Perisphinctidae, and Kosmoceratidae are much less 

common. The Phylloceratidae and Reineckeiidae are 

of minor importance.

Other megafossils collected from Upper Jurassic beds 

in east-central Oregon and western Idaho consist only 

of pelecypods. They include 3 specimens of Posidonia, 

20 of Ostrea, and 50 of Gryphaea. Many more specimens of Gryphaea could have been readily collected 

from exposures near Mineral, Idaho.

STRATIGRAPHY SUMMARY 

NORTHEASTERN OREGON AND ADJOINING IDAHO

Jurassic black shale at least 1,000 feet thick is well 

exposed in the Snake River Canyon in the extreme 

northeast corner of Oregon and in adjoining Idaho 

(Morrison, 1961, p. 107-110) (fig. 1). The shale is 

black, thin bedded, evenly bedded, hard, and noncalcareous; it contains some interbedded quartz sandstone and chert pebble conglomerate; it is marked 

basally by a clean crossbedded sandstone that includes 

large limestone boulders; and it rests with angular 

unconformity on Triassic limestone and conglomerate.

One notable feature of this shale is a paucity of fossils. 

A few ammonites were found at one spot after many 

hours of labor. Elsewhere not a trace of a fossil was 

found in spite of the fact that exposures are fairly 

extensive. Large areas of bedrock and talus were 

examined by R. F. Morrison and the writer during the

summer of 1962 without finding fossils. Even the 

particular beds that yielded the ammonites did not 

contain any fossil remains on weathered surfaces. 

Apparently the bottom conditions during deposition 

were unfavorable for benthonic organisms and present 

weathering conditions destroy any fossils that become 

exposed.

MINERAL AREA, WESTERN IDAHO

The Jurassic rocks exposed in the canyon of Dennett 

Creek near the old mining town of Mineral (abandoned), 

Idaho, have been described by Livingston (1932, 

p. 33, 34) as follows:

The lowest rock exposed is a quartz diorite sill. The bottom 

of the sill has not been exposed but the top grades through a 

purplish andesitic phase into a reddish rock to which the field 

name of Lower Rhyolite has been assigned to distinguish it from 

a flow of rhyolite higher in the series.

Immediately above this reddish rock lies a fine gray sandy 

tuff, which merges upward into a series of coarse pebble conglomerates. Above the conglomerate lie more tuffs, darker in 

color, and above these a series of dark carbonaceous and calcareous shales about 200 to 300 feet thick. The whole series 

from the top of the quartz diorite to the top of the shales is 

between 500 and 600 feet thick.

The shales yield excellent fossil ammonites which have been 

identified by Dr. Packard of the University of Oregon and by 

Ralph L. Lupher of Washington State College, as Upper Jurassic 

in age.

Above the dark shale is a rhyolitic unit as much as 

200 feet thick and above that is a schistose agglomerate 

that Livingston interprets as a fault gouge. These 

appear to be much younger than the Jurassic.

The sequence near Mineral, Idaho, is virtually as 

described by Livingston according to observations made 

in 1959 and 1962 by Norman Wagner and Howard 

Brooks of the Oregon Department of Geology and 

Mineral Resources and by the writer. The dark shale 

and the underlying sandy tuff crop out on the south

TABLE 1. Ammonite genera and subgenera from beds of Late Jurassic age in eastern Oregon and western Idaho, showing biological

relationships and relative numbers available for study

Family

Lytoceratidae. _________ ___

Macrocephalitidae. _____

Kosmoceratidae. __________

Cardioceratidae _____ _ ____

Reineckeiidae _____ __ _ _

Perisphinctidae. ______

.

Subfamily

Cardioceratinae_ ______ ________ __

Pseudoperisphinctinae, __________ __

Genus and subgenus

Xenocephalites- _ ________ _ _ ______________

Lilloettia- _ _ _ __ ________ ______ ___ _ ____

Lilloettia? _ _________________ ___ ______

Cardioceras (Scarburgiceras) ____________ __ ___

Cobbanitesf ______________________ _______ _

Number of 

specimens

2

1

1

11

20

49

18

5

1

41

5

1

7

9

4
UPPER JURASSIC MOLLUSKS FROM OREGON AND IDAHO D3

45°45'

R. 4 W 116°45' R. 3 W.

WALLOWA COUNTY

\

\

R 2 W

NEZ PERCE COUNTY

5 MILES 

1

\

\

R.47 E. R. 48 E. R. 49 E. R.50 E.

FIGUEE 1. Index map showing Upper Jurassic fossil locality in west-central Idaho. Number on map refers to that given in table 2.

side of Dennett Creek near its junction with the North 

Fork and on both sides of the canyon of the North Fork 

of Dennett Creek for about 1 mile north of Mineral. 

They also crop out extensively along the south side of 

the Middle Fork for at least 1% miles above its junction 

with the North Fork (fig. 2).

The shale is dark gray, calcareous, weathers into 

chunky to conchoidal fragments, contains many black 

brittle concretions, and is probably several hundred 

feet thick. The concretions yielded only the spat of 

oysters or Gryphaeas. Nevertheless the ammonites 

reported by Livingston from the shale in Dennett Creek 

at his locality 88 were probably obtained from similar 

concretions. The ammonites are preserved in a black 

limestone matrix, are mostly undeformed, and are 

identical specifically and in preservatoin with ammonites 

obtained from concretions in the Trowbridge Formation 

of Lupher (1941) on Flat Creek in the Izee area of

east-central Oregon. Presumably during the months 

that Livingston (1932, p. 31) mapped the geology of the 

Mineral area, either he or his students were fortunate to 

find some concretions containing ammonites.

The sandy tuff beds underlying the dark shale are 

mostly thin to medium bedded, gray to brownish gray, 

weather reddish to yellowish brown, range in thickness 

from a few feet to at least 100 feet, and grade upward 

into shale within a few feet. They are best exposed 

along the North Fork of Dennett Creek from % to % 

mile above its mouth. Their upper part contains 

fairly well preserved Gryphaeas that were found in 

abundance only on the east side of the North Fork about 

320 feet above the creekbed in the NE#N"W% sec. 9, 

T. 14 N., R. 6 W. This is the place from which W. R. 

Wagner (written communication dated Dec. 31, 1962) 

obtained the Gryphaeas that were examined by J. B. 

Reeside, Jr. These were erroneously reported to be
D4

R.45E.

CONTRIBUTIONS TO PALEONTOLOGY

R.46E. 117°05' R.6W

44°35

R 7 W.

FIGUKE 2. Index map showing Upper Jurassic fossil localities near Mineral (abandoned), Idaho. Numbers on map refer to those given In table 2.

from the Snake River Canyon in Oregon (McKee and 

others, 1956, p. 2).

EAST-CENTRAL OREGON

In east-central Oregon (fig. 3) near Izee, Callovian 

fossils have been obtained from more than 13,000 feet 

of sedimentary rock which includes all the Lonesome 

and Trowbridge Formations of Lupher (1941) and the 

upper part of the Snowshoe Formation of Lupher (1941). 

Most of the fossils were obtained from concretions in 

the upper part of the Snowshoe Formation and in the 

middle and lower middle parts of the Trowbridge 

Formation. A few fossils were obtained from mudstone 

and graywacke in various parts of the Lonesome 

Formation from about 1,250 feet above its base (Mesozoic loc. 26782) to within 300 feet of its eroded top 

(Mesozoic loc. 27383) as exposed near the junction of 

Lewis Creek with the South Fork of the John Day 

River.

Most of the fossils obtained from these formations 

are ammonites. However, from the concretions in the 

upper part of the Snowshoe Formation were obtained 

20 nondescript oysters and 1 specimen of the pelecypod 

Posidonia. This genus is represented, also by two 

specimens from a tuffaceous bed in the Lonesome 

Formation.

The lithologic characteristics of the formations of 

Callovian age in the Izee area have been described by

Lupher (1941, p. 227, 259-266) and Dickinson (1962a, 

p. 251-153; 1962b, p. 48'3). In brief, the Snowshoe 

Formation is about 3,000-3,500 feet thick and consists 

of dark gray to black thin-bedded mudstone, volcanic 

siltstone, and sandstone. The Trowbridge Formation 

is 2,750-3,250 feet thick and consists mostly of black 

mudstone, but it contains some thin beds of volcanic 

sandstone and dark limestone. In addition its lower 

900 feet contains green mudstone and four units of 

clastic volcanic rocks that range from volcanic sandstone to vitroclastic tuff. The lowermost of these units 

crops out as conspicuous cliffs about 400 feet above the 

base of the Trowbridge Formation.

The Lonesome Formation in the Izee area consists of 

thick-bedded volcanic graywacke and interbedded dark 

gray to black mudstone but includes some conglomeratic 

beds. It is characterized by thick cliff-forming units 

of graywacke, by graded bedding, and by sole markings. Its thickness was considered by Lupher (1941, 

p. 265, 266) to be about 4,000 feet and by Dickinson 

(1962a, p. 252, 253) to be at least 10,000 feet. Dickinson, after a field conference with Lupher, however, 

selected a much lower unit for the base of the formation 

than that originally selected by Lupher (oral communication from Dickinson, 1957).

The Lonesome Formation in the Sawtooth Creek 

quadrangle, south of the Izee area, has been studied by 

Marvin Beeson for a master's thesis at the University
R. 26 E. 119°30' R. 27 E. R. 28 E. R. 29 E. R.30 E. 

GRANT COUNTY 

HARNEY COUNTY

FIGURE 3. Index map showing Upper Jurassic fossil localities near Izee in east-central Oregon. Numbers on map refer to those give
D6 CONTRIBUTIONS TO PALEONTOLOGY

of Oregon and has been described by him (written 

communication of Dec. 30, 1962) as follows:

In the Sawtooth Creek quadrangle the Lonesonie Formation 

consists mostly of interbedded volcanic graywacke and black 

mudstone, contains a few pebble beds near its middle, and is 

estimated to be approximately 10,000 feet thick. About 4,000 

feet of black mudstone that contains very few beds of graywacke 

is exposed in the upper part of the formation along the South 

Fork of the John Day River just south of its junction with Bear 

Creek. A bed of light-colored pinkish gray, fossiliferous tuff 

occurs in the N.W. corner of sec. 13, T. 20 S., R. 28E.

CONDITIONS OF DEPOSITION

The black shale exposed in the Snake River Canyon 

in the northeast corner of Oregon and in adjoining 

Idaho appears to have been deposited in quiet water as 

indicated by its even and thin bedding. The absence 

of benthonic organisms could reflect rapid sedimentation, a muddy bottom, a considerable depth of water, 

or a combination of these possibilities. The lack of 

calcareous material could mean that the waters were 

cool and had a northern source. This is suggested by 

the fact that the shale contains the ammonite Cardioceras which is a northern migrant and that similar 

Cardioceras-be&rwg shale in Alaska is likewise noncalcareous.

The Jurassic beds exposed near Mineral, Idaho, are 

of shallow water origin as shown by the presence of 

Gryphaeas in the basal sandy tuffs and the spat of 

oysters or Gryphaeas in concretions in the overlying 

dark-gray shale.

The upper part of the Snowshoe Formation that 

contains early Callovian ammonites is also considered 

to be of shallow-water origin as shown by the occurrence 

of oysters in concretions associated with ammonites or 

attached to ammonites.

The Trowbridge and Lonesome Formations were deposited very rapidly as shown by their enormous thicknesses, flyschlike characteristics, and the presence almost throughout of ammonites of early Callovian age. 

The absence of benthonic organisms could be explained 

by rapid deposition, or considerable depth of water, or 

both.

AGES AND CORRELATIONS

UNNAMED BEDS IN NORTHEASTERN OREGON AND 

ADJOINING IDAHO

Five small ammonites belonging to the genus Cardioceras were obtained at one spot from black shale exposed 

on the Idaho side of the Snake River Canyon near the 

northeastern corner of Oregon (USGS Mesozoic loc. 

28652). These ammonites are identical with the inner 

whorls of Cardioceras (Scarburgiceras) martini Reeside 

(1919, p. 2,7, 28, pi. 9, figs. 5-8) from the basal part of 

the Naknek Formation in the Cook Inlet region,

Alaska. In that region Cardioceras occurs directly below beds containing the ammonite Amoeboceras and the 

pelecypod Buchia concentrica (Sowerby) of late Oxfordian to early Kimmeridgian age.

The genus Cardioceras in northwest Europe occurs in 

the lower part of the Oxfordian stage (zones of Quenstedtoceras mariae to Perisphinctes plicatilis inclusive). 

The subgenus Scarburgiceras is characteristic of the 

European zone of Quenstedtoceras mariae (Arkell, 1941, 

p. Ixxvii) but ranges higher into the lower part of the 

zone of Cardioceras cordatum (Arkell, 1956, p. 548).

The presence of beds of early Oxfordian age in the 

Snake River Canyon is interesting because beds of that 

age have not hitherto been identified faunally in California, Oregon, Washington, or western Idaho. They 

are widespread, however, in the western interior of the 

United States (Reeside, 1919) and in western Canada 

including many places in western British Columbia 

(Frebold, 1957, p. 29, 30; Frebold and others, 1959, 

p. 1-11).

UNNAMED BEDS NEAR MINERAL, IDAHO

Some ammonites reported by D. C. Livingston (1932, 

p. 33, 34) to be from dark shale exposed in the canyon 

of Dennett Creek near Mineral include Xenocephalites 

mcarius Imlay, Lilloettia buckmani (Crickmay), and 

L. cf. L. mertonyarwoodi Crickmay.

Another collection of ammonites (USGS Mesozoic 

loc. 28651) from shale exposed in a roadcut near the 

junction of the road along Dennett Creek with a road 

up the North Fork includes Xenocephalites cf. X. mcarius 

Imlay, Lilloettia? sp., and Cobbanites sp. juv.

These ammonites are identical with those from the 

Trowbridge Formation and with some of the ammonites 

from the upper part of the Snowshoe Formation of 

east-central Oregon. As in those formations, Xenocephalites and Lilloettia provide correlation with the 

lower third of the Chinitna Formation of Alaska which 

is correlated with the lower Callovian of Europe (Imlay, 

1953b, p. 51-53).

The sandy tuffaceous beds underlying the dark shale 

at Dennett Creek appear to be of Jurassic age and 

probably are not much older than the shale. This is 

indicated by the gradational contact between the shale 

and tuffaceous beds and by the presence of many specimens of Gryphaea of post-Triassic aspect in the upper 

part of the tuffaceous beds.

The only recorded specimens of Triassic Gryphaea, 

according to Cox (1952, p. 79), are from the Upper 

Triassic beds of northern Italy (Scalia, 1912, p. 21-23, 

pi. 2, figs. 6-21) and from Bear Island (Bareninsel) 

near Spitzbergen (Bohm, 1903, p. 16, 17, pi. 1, figs. 

35-41, 44-46, 49-54; Frebold, 1951, p. 74). The specimens from those places do not bear sulci on the left
UPPER JURASSIC MOLLUSKS FROM OREGON AND IDAHO D7

valve as do many Jurassic Gryphaeas, and they are less 

than an inch in height, which dimension is much less 

than in normal Jurassic Gryphaeas. They are placed 

in Gryphaea because of their strongly convex left valve 

and incurved beak.

In contrast with these Triassic species, the species 

of Gryphaea from Dennett Creek, Idaho, is comparable 

in size and ornamentation with Jurassic species. In 

particular it resembles G. calceola Quenstedt from the 

lower Bajocian (Aalenian) of Europe (Quenstedt, 1858, 

pi. 48, figs. 1-3) and from the Bajocian to Callovian 

of Argentina (Gottsche, 1878, pi. 5, figs. 17 a, b, 18 a-c; 

Weaver, 1931, pi. 19, fig. 93).

SNOWSHOE FORMATION OF LUPHEB, 1941, IN 

EAST-CENTRAL OREGON

The upper part of the Snowshoe Formation in the 

Izee area, as mapped by W. R. Dickinson (1962a, p. 

253), has furnished the ammonites (table 2) Lytocerast 

sp., Calliphylloceras sp., Xenocephalites vicarius Imlay,

Lilloettia cf. L. buckmani (Crickmay), L. sp., Kepplerites (Gowericeras) cf. K. (G.) torrense (McLearn), 

Parareineckeia cf. P. hickersonensis Imlay, Cobbanites 

cf. C. talkeetnanus Imlay, and Choffatia (Loboplanulites) 

cf. C. (L.) ceralis Arkell.

These fossils were collected from concretions in 

thin-bedded mudstone and siltstone about 500-1,000 

feet below the unconformable upper contact with the 

Trowbridge Formation (written communication from 

W. R. Dickinson, May, 1963). Most of the fossils 

were obtained at or near the top of a divide between 

Antelope Creek and Rosebud Creek in sec. 14, T. 17 S., 

R. 28 E. (USGS Mesozoic loc. 26778).

Of the ammonite genera listed, Xenocephalites, Lilloettia, and Kepplerites are good evidence of a Callovian age, whereas Parareineckeia, Cobbanites, and 

Choffatia indicate a Bathonian to Callovian age. Xenocephalites has been recorded from beds of early Callovian 

age in Alaska (Imlay, 1953b, p. 51-53, 78, 79; 1962a, 

p. C3), in the western interior of Canada (Frebold,

TABLE 2. Geographic distribution of Upper Jurassic mollusks in east-central Oregon and western Idaho

[Numbers 1-19 refer to those in figs. 1-3. Most of the larger numbers refer to Mesozoic collections in the U.S. Geol. Survey. Collections referred to Livingston and Lupher 

are at the California Acad. of Sci. Collections referred to Dickinson are at Leland Stanford Junior Univ.]

Ostrea sp __ - ______

Phylloceras sp.---.-. ........

Xenocephalites vkarius Imlay. 

cf. X. vicarius Imlay....

Lilloettia buckmani (Crickcf. L. buckmani (Crickcf. L. mertonyarwoodi

sp............. ..........

? sp. __ ...............

Kepplerites (Oowericeras) cf. 

K. (G.) torrensi (McLearn)

?SP. ---------.--.._--------

Cardioceras (Scarburgkeras)

Parareineckeia cf. P. hickerCobbanites afl. C. talkeet9 qr\

Choffatia (Loboplanulites?) cf.

Idaho

Nez 

Perce 

County

Snake 

River 

Canyon

Washington 

County

Mineral area

Unnamed beds

1

1

00

X

2

Livingston

88

X

o

X

So

g

X

3

1O

1

X

Oregon

Grant County

Izee area

Snowshoe formation 

of Lupher, 1941

4

a 5 £

X

5

6CO 

CM C<1

6

00

§CQ

X

7

t 

X

Lonesome formation 

of Lupher, 1941

8

SO

9

CO

X

10

S

KCM

X

11

Dickinson 

124 F 

....

12

K 

g

X

13

rX

Trowbridge formation of Lupher, 

1941

14

J3 cH

r

II

r

l°fteo 3 1-1 

^

X

%~aS3~

X

£<* a co 3~ I-&CO 3~

X

Dickinson 

121 F 

X

Dickinson F122

Harney County

Sawtooth Creek 

quadrangle

Lonesome formation 

of Lupher, 1941

15

o

§(N

16

S00

17

00W

18

l~

00 

CN

19

§ 

%CN

X

X

g00

X
D8 CONTRIBUTIONS TO PALEONTOLOGY

1957, p. 3, 24, 58, 59) and the United States (Imlay, 

1953a, p. 6, 8, 18, 19), in southern Mexico (Burckhardt, 

1927, p. 33, pi. 16, figs. 4-9), and in Argentina (Stehn, 

1924, p. 86-88, 92). The recorded occurrence of Xenocephalites from beds of Bathonian age in East Greenland (Spath, 1932, p. 45, 133) is erroneous according to 

Calloman (1959, p. 507) who says that the specimen 

assigned to Xenocephalites by Spath (1932, p. 44) is a 

septate nucleus of Cranocephalites. One ammonite 

fragment questionably assigned to Xenocephalites (Imlay, 1962a, p. C22) has been found in western Montana 

in beds of probable late Bathonian age.

Lilloettia has been recognized to date only in beds of 

early to middle Callovian age in Alaska (Imlay, 1953b, 

p. 50, 52-54, 75-78) and western British Columbia 

(Crickmay, 1930, p. 60-62) and in beds of early Callovian age in Montana (Imlay, 1953a, p. 18).

Kepplerites and its subgenera, Seymourites and Gowericeras, occur in beds of early Callovian to early middle 

Callovian age in Alaska (Imlay, 1953b, p. 51-53, 95- 

99), in the Queen Charlotte Islands (McLearn, 1929, 

p. 4-12), in western Alberta (Frebold, 1957, p. 63, 64), 

in Montana (Imlay, 1953a p. 6-8, 25-28), and in East 

Greenland (Spath, 1932, p. 138, 139, 145, 146; Calloman, 1959, p. 508, 509). In northwest Europe Kepplerites ranges through the entire Lower Callovian 

(Calloman, 1955, p. 255, 1959, p. 511; Arkell, 1953, 

p. 117, 119). Calloman (1959, p. 507-511) noted, also, 

that the lowest occurrence of Kepplerites in Greenland 

is of latest Bathonian age, apparently on the basis that 

the overlying beds, belonging to the Kepplerites tychonis 

zone, contain the same species of Kepplerites as occur 

in the Macrocephalites macrocephalus zone of Europe.

Parareineckeia has been found previously only in 

south-central Alaska, associated in the lower part of its 

range with ammonites of probable late Bathonian age 

(Imlay, 1962a, p. C20, C25, C26) and associated in the 

upper part of its range with ammonites of early Callovian age (Imlay, 1953b, p. 54, 101, 102; 1962a, p. C26). 

The species of Parareineckeia from the upper part of the 

Snowshoe Formation closely resembles the species of 

probable Bathonian age from Alaska.

Cobbanites has been found previously in southcentral 

Alaska, in western Alberta, and in western Montana. 

In Alaska it occurs in the basal part of the Chinitna 

Formation of early Callovian age (Imlay, 1953a, p. 33) 

and in underlying beds of probable Bathonian age 

(Imlay, 1962a, p. C27). In Alberta it includes "Procerites" engleri Frebold (1957, p. 65, pi. 39, fig. 1, pi. 40, 

figs, la, b) which is associated with other ammonites, 

such as Kepplerites and Xenocephalites of early Callovian age (Frebold, 1957, p. 21, 23) in a 4-foot bed 

characterized by Gryphaea impressimarginata McLearn. 

In Montana, Cobbanites occurs in the upper part of the

Sawtooth Formation of probable late Bathonian age 

(Imlay, 1962a, p. C27, C28) and in the lower part of the 

Rierdon Formation of early Callovian age (Imlay, 

1953a, p. 33, pi. 23, figs. 13, 17, pi. 24, figs. 9-11) 

associated with Gryphaea impressimarginata McLearn. 

The highest occurrences in the Rierdon Formation are 

in beds containing Kepplerites (Gowericeras) and 

Gryphaea nebrascensis Meek and Hayden which is 

stratigraphically higher than the beds containing 

Gryphaea impressimarginata McLearn.

The ammonite Chofatia is reported by Arkell (1958, 

p. 211) to range from middle Bathonian to middle 

Callovian in northwest Europe. The Oregon species is 

assigned to the subgenus Loboplanulites Buckman 

(1925, pi. 596; Arkell, 1958, p. 212) because of its 

rounded slightly depressed whorl section and its strong 

widely spaced primary ribs. The subgenus has the 

same range as the genus but is particularly common in 

the upper Bathonian of Europe. Chofatia "is the only 

ammonite genus known to pass in strength across the 

boundary between the Bathonian and the Callovian" 

(Arkell, 1958, p. 235, 236).

The ranges of the ammonites from the upper part of 

the Snowshoe Formation show that that part of the 

formation is of early Callovian age, provided the genera 

listed actually occur together. Such association canriot be certain, however, as the ammonites were collected from concretions scattered over a considerable 

area. Therefore, the age of the upper part of the Snowshoe Formation could be partly late Bathonian as well 

as early Callovian. This does not seem likely but 

cannot be excluded as a possibility.

In considering the exact age of the upper part of the 

Snowshoe Formation, the absence of the ammonite 

Cadoceras in the collections may be significant because 

that genus in Alaska is very common in the Chinitna 

and Shelikof Formations of early to middle Callovian 

age (Imlay, 1953b, p. 50-54). Its absence in the upper 

part of the Snowshoe Formation might be explained by 

unfavorable ecological conditions, by insufficient collecting, or by deposition of the Snowshoe Formation 

before Cadoceras existed, or became common, in the 

Pacific coast province. The last possibility is suggested by the fact that in the Cook Inlet region, Alaska 

the upper 600-650 feet of the Bowser Formation underlying the Chinitna Formation contains an early Callovian ammonite assemblage that does not include 

Cadoceras (Imlay, 1962a, p. C3). By comparison, the 

failure to find Cadoceras in the Snowshoe Formation in 

association with such typical Callovian genera as 

Kepplerites, Xenocephalites, and Lilloettia suggests that 

the beds containing those ammonites are not younger 

than earliest Callovian.

The presence of fossils of late Bathonian (?) to early
UPPER JURASSIC MOLLUSKS FROM OREGON AND IDAHO D9

Callovian age in the upper part of the Snowshoe 

Formation is interesting because the lower and middle 

parts of the formation have furnished ammonites of 

late Toarcian to middle Bajocian age (see list in Imltay, 

1959, p. 105), but none of late Bajocian age or of definite 

Bathonian age such as occur in south-central Alaska 

(Imlay, 1962a and 1962b). Failure to find fossils of 

those ages in Oregon may be a result of poor exposures, 

or inadequate time spent collecting, or absence of beds. 

A disconformity would be difficult to detect in the 

Snowshoe Formation because it consists of a repetitious 

sequence of soft thin-bedded mudstone, siltstone, and 

sandstone that weathers easily into rounded surfaces 

that are generally covered with soil and vegetation. 

The presence of a disconformity is suggested by the 

fact that as yet there is no definite faunal evidence 

for the presence of the late Bajocian or the Bathonian 

in the Pacific coast region south of the Cook Inlet 

region, Alaska.

TROWBRIDQE FORMATION OF LUPHER, 1941, IN 

EAST-CENTRAL OREGON

The middle and lower middle parts of the Trowbridge 

Formation cropping out near Flat Creek in sec. 15, 

T. 18 S., R. 27 E., Grant County, have furnished the 

ammonites (table 2) Xenocephalites? sp., Lilloettia 

buckmani (Crickmay), L. cf. L. mertonyarwoodi Crickmay, L. sp., and Kepplerites (Gowericeras) cf. K. (G.} 

torrensi (McLearn).

These ammonites by comparison with the Jurassic 

faunas of Alaska (Imlay, 1953b, p. 50-54) are of early 

to early middle Callovian age. They differ from the 

assemblage in the upper part of the Snowshoe Formation by lacking such genera as Paraeineckeia, Cobbanites, 

and Choffatia that could be of Bathonian age. Their 

presence shows that the Trowbridge Formation is nearly 

of the same age as the upper part of the Snowshoe 

Formation.

LONESOME FORMATION OF LUPHER, 1941, IN 

EAST-CENTRAL OREGON

The Lonesome Formation has yielded some ammonites at places throughout its great thickness but 

most of them are wretchedly preserved and many 

cannot be identified generically. An abundance of 

ammonites was found only at USGS Mesozoic localities 

28666 and 28376. The fossils present include (table 

2) Phylloceras sp., Xenocephalites vicarius Imlay, X. 

cf. X. vicarius Imlay, X.I sp., Lilloettia cf. L. stantoni 

Imlay, L.? sp., Pseudocadoceras? sp., Cobbanites sp. 

juv., C.? sp., Posidonia ornati Quenstedt.

In the Izee area, fragments assigned questionably to 

Xenocephalites and Lilloettia were obtained in the 

middle and upper parts of the 10,000 feet of the Lone716-828 O 64 2

some Formation exposed along the South Fork of the 

John Day River between Antelope Creek and Lewis 

Creek. One specimen referred to Xenocephalites? was 

found within 300 feet of the top of that sequence 

(USGS Mesozoic loc. 27383). Xenocephalites cf. X. 

vicarius Imlay was collected within 1,250-1,500 feet 

of the base of the formation in a roadcut near Antelope 

Creek (USGS Mesozoic loc. 26782). X. vicarius 

Imlay was collected about 4,000 feet above the base 

of the formation in an outcrop on the South Fork 

about 3,000 feet southeast of the mouth of Antelope 

Creek (USGS Mesozoic loc. 26781).

Elsewhere in the Izee area, some crushed limonitic 

molds, probably representing immature forms of 

Pseudocadoceras, were collected on the south side of 

Flat Creek near the middle of the Lonesome Formation 

(USGS Mesozoic loc. 26780).

In the Sawtooth Creek quadrangle, south of the Izee 

area, the Lonesome Formation has furnished Xenocephalites vicarius Imlay, Lilloettia cf. L. stantoni 

Imlay, Cobbanites sp. juv., and Pseudocadoceras? sp. 

The stratigraphic position of these ammonites within 

the formation is unknown.

These ammonites by comparison with the Jurassic 

faunas in Alaska and Europe (Imlay, 1953b, p. 50-54) 

show that the Lonesome Formation is mostly or entirely 

of early Callovian age. The presence of Xenocephalites 

is excellent evidence for an early Callovian age. 

Lilloettia occurs with Xenocephalities in Alaska but 

ranges a little higher into beds that probably correspond 

to the early middle Callovian (Kosmoceras jason zone) 

of Europe (Imlay, 1953b, p. 52, 53). Cobbanites has 

not been found in beds younger than early Callovian 

(Imlay, 1962a, p. C27, C28). Pseudocadoceras in 

Europe ranges through most of the Callovian (Calloman, 1955, p. 255) but is absent in the basal zone of 

Macrocephalites macrocephalus and in the highest Callovian. In Alaska it is likewise missing from the lowest 

1,800 to 2,500 feet of the Callovian sequence as discussed 

elsewhere (Imlay, 1962a, p. C6).

On the basis of the ranges of these ammonites, the 

entire Lonesome Formation exposed along the South 

Fork near Izee is of early Callovian age because it 

contains Xenocephalites, or fragments probably belonging to that genus, throughout most of its thickness. 

The presence of Lilloettia? at two places in association 

with Xenocephalites? is not evidence for a middle 

Callovian age considering that the two genera are 

normally associated in Alaska only in beds of early 

Callovian age.

Likewise, most of the collections from the Lonesome 

Formation in the Sawtooth Creek quadrangle are of 

early Callovian age on the basis of the presence of
D10 CONTRIBUTIONS TO PALEONTOLOGY

Xenocephalites in association with Lilloettia or with 

Cobbanites.

The only collections that could be of middle Callovian 

age are those containing questionable Pseudocadoceras 

from south of Flat Creek (USGS Mesozoic loc. 26780) 

and from the Sawtooth Creek quadrangle (USGS 

Mesozoic loc. 28667). Pseudocadoceras by itself, however, is not evidence for an age younger than late early 

Callovian (zone of Sigaloceras calloviense).

An early Callovian age assignment for the Lonesome 

Formation is rather astonishing considering its enormous thickness and that ammonites of the same age 

occur in the Trowbridge Formation and in the upper 

part of the Snowshoe Formation. Evidently sedimentation in east-central Oregon was exceedingly rapid 

during Callovian time. Such rapid sedimentation may 

account for the absence of benthonic organisms except 

for some small oysters that were found in concretions 

in the upper part of the Snowshoe Formation.

COMPARISONS WITH OTHER FAUNAS 

ALASKA AND WESTERN BRITISH COLUMBIA

The Upper Jurassic (Callovian and Oxfordian) 

ammonites from east-central Oregon and westernmost 

Idaho, described herein, are identical or closely similar 

to species from western British Columbia, the Alaska 

Peninsula, and the Cook Inlet region, Alaska.

Among the Callovian ammonites, Lilloettia buckmani 

(Crickmay) occurs elsewhere in the Mysterious Creek 

Formation in the Harrison Lake area, British Columbia 

(Crickmay, 1930, p. 62, pi. 20, figs. 1-4), in the lower 

two-thirds of the Chinitna Formation in the Cook Inlet 

region, Alaska, and in the lower member of Shelikof 

Formation on the Alaska Peninsula (Imlay, 1953b, 

p. 50). Xenocephalites vicarius Imlay occurs in the 

lower third of the Chinitna Formation (Imlay, 1953b, 

p. 50) and in the upper part of the underlying Bowser 

Formation in Alaska. Kepplerites (Gowericeras) occurs 

in the lower half of the Chinitna Formation, Alaska 

(Imlay, 1953b, p. 50), and in the upper part of the 

Yakoun Formation in the Queen Charlotte Islands 

(McLearn, 1929, p. 10, 11). The Oregon specimens 

of Parareineckeia and Cobbanites resemble species from 

the Bowser Formation in Alaska (Imlay, 1962a, p. 

C25-C27), although similar species occur in the lower 

part of the Chinitna Formation (Imlay, 1953b, p. 102) 

and in the lower part of the Shelikof Formation (Imlay, 

1953b, p. 101). The genus Parareineckeia has been 

found only in Alaska and Oregon. Cobbanites has been 

found in these States and in the western interior of 

North America.

The ammonites of early Oxfordian age from the 

canyon of the Snake River in Idaho are identified with 

Cardioceras (Scarburgiceras) martini Reeside (1919,

p. 27), which until now has been found only in the basal 

part of the Naknek Formation in the Cook Inlet region, 

Alaska.

CALIFORNIA

The beds of Callovian age in eastern Oregon and 

western Idaho have very little in common faunally 

with the Upper Jurassic of California. The presence 

of Kepplerites (Gowericeras) in the Snowshoe and Trowbridge Formations in east-central Oregon is comparable 

with the occurrence of the subgenus in the Colfax 

Formation of Smith near Colfax, Calif. (Imlay, 1961, 

p. D6, D7). The presence of Pseudocadoceras? at two 

localities in the Lonesome Formation is possibly comparable with some of the occurrences of Pseudocadoceras 

in California (Imlay, 1961, p. D5, D6, D9). Xenocephalites has not been identified definitely in California, 

although it is possibly present in the Taylorsville area 

(Imlay 1961, p. D9). The species of Choffatia from 

the Snowshoe Formation in Oregon belongs to a different subgenus than Choffatia hyatti (Crickmay) (1933, 

p. 901, 913, 914; Imlay, 1961, p. D9) from the North 

Ridge Formation of Crickmay in the Taylorsville area. 

The Callovian beds of California have furnished such 

ammonites as Cadoceras, Peltoceras, and Grossouvria 

that have not yet been found in Oregon or in western 

Idaho.

This paucity of faunal resemblances between the 

Callovian of Oregon and California is not evidence, 

however, that the faunas lived in different basins or 

provinces. Actually the lowest beds of Callovian age 

in California have furnished very few ammonites. 

Most of the Callovian ammonites from higher beds, 

such as the Logtown Ridge Formation and the Foreman 

Formation, indicate ages ranging from late early 

Callovian (Sigaloceras calloviense zone) to late Callovian 

(Imlay, 1961, p. D5-D9). In contrast most of the 

Callovian ammonites from eastern Oregon and western 

Idaho indicate an early Callovian age not younger than 

the Sigaloceras calloviense zone of Europe. The evidence for that zone, or for the middle Callovian is very 

weak as it consists only of fragmentary ammonites 

that are described herein, questionably as Pseudocadoceras. To date no faunal evidence has been found 

for the presence of beds of early Oxfordian age in 

California, or in southwestern Oregon, although ammonites of late Oxfordian age have been found in both 

places (Imlay, 1961, p. D7-D8, pi. 4, fig. 2).

WESTERN INTERIOR OF NORTH AMERICA

Beds of early Callovian age in the western interior of 

the United States and Canada have not furnished any 

specimens of Parareineckeia, Choffatia, and Pseudocadoceras which occur in beds of that age on the Pacific
UPPER JURASSIC MOLLUSKS FROM OREGON AND IDAHO Dll

coast. They have furnished a few specimens of 

Xenocephalites (Imlay, 1953a, p. 6, 18, 19; Frebold, 

1957, p. 58), Lilloettia (Imlay, 1953a, p. 6, 18), and 

Cobbanites (Imlay, 1962a, p. C26-C28) which are 

fairly common in beds of early Callovian age on the 

Pacific coast. The presence of these genera suggests a 

marine connection westward during Callovian time 

with marine waters in the Pacific coast region. Nevertheless, the early Callovian ammonite faunas of the two 

regions have few, if any, species in common, contain 

different associations of genera and subgenera, and 

some of the ammonite genera that are common in one 

region are rare or have not been found in the other 

(Imlay, 1953a, p. 8; 1953b, p. 54, 55).

These distinctions between the Callovian faunas of 

the two regions could reflect barriers, or ecological 

differences, or the presence of disconformities in one 

region not present in the other, or combinations of these 

possibilities as has been discussed by Frebold (1957, p. 

27).

Beds of Oxfordian age are widespread in the western 

interior of the United States (Imlay 1952, p. 964, 965,

968) and Canada (Frebold, 1953; 1957, p. 27-31). 

They are characterized by the ammonite genus Cardioceras (Reeside, 1919; Frebold and others, 1959) of 

which some species resemble Cardioceras (Scarburgiceras) 

martini Reeside from Alaska. Evidence for direct 

marine connection of the Oxfordian sea of the western 

interior region of Canada with a sea in the Pacific 

coast region through British Columbia has been postulated and discussed by Frebold (1957, p. 31; Frebold 

and others, 1959, p. 16). Direct marine connections 

westward from the western interior region of the United 

States seems unlikely considering that the marine 

beds of early Oxfordian age become sandier westward 

(Imlay and others, 1948; Imlay, 1957, p. 481, 482; 

1956, p. 595-598).

GEOGRAPHIC DISTRIBUTION

The occurrence by area and locality of the fossils 

described herein are indicated in table 2. The positions of the areas are shown in figures 1-3. Detailed 

descriptions of the individual localities are given in the 

following table.

Descriptions of upper Jurassic fossil localities in east-central Oregon and western Idaho

No. on figs. 1-3

1_ __ _____

2 _ ___ _

2___._..__

2_________

3_________

4 ______

5_________

5_________

6_________

7__.______

8_._______

Geological 

Survey 

Mesozoic 

localities

28652

20389

27582

28651

27367

26778

26779

27368

27369

26782

Collector's 

field numbers

F-12_____________

88-__----_.______

I58-8-27C____._._

F115(3-48-l)_____

Fl 15(3-48-2) ____

I58-8-28A________

I58-8-28B. _______

F125.____________

Collector, year of collection, description of locality, and stratigraphic assignment

R. F. Morrison, R. W. Imlay, and H. C. Brooks, 1961 and 1962. From black hard

mudstone % mile S. 80° E. of mouth of Slate Creek, 1% miles N. 5° W. of mouth 

of Cottonwood Creek and % mile east of Snake River on north side of small creek. 

Probably in NW% sec. 8, T. 30 N., R. 4 W. (unsurveyed) . Nez Perce County, 

Idaho. Unnamed beds about 400 feet above top of Triassic. 

D. C. Livingston. Collected prior to 1932. Label states "from shales in Snake

River Canyon near Mineral, Idaho." Livingston (1932, p. 34) stated that the 

collection was made in the canyon of Dennett Creek near Mineral, Idaho. 

W. R. Wagner, 1945. North Fork of Dennett Creek, NW% sec. 9, T. 14 N., R. 6 W.,

Washington County, Idaho. From tuffaceous sandstone. 

R. W. Imlay, N. S. Wagner, and H. C. Brooks, 1959. East side of North Fork of

Dennett Creek, about 320 ft above streambed, in NE^NW^ sec. 9, T. 14 N., 

R. 6 W., Washington County, Idaho. From tuffaceous sandstone overlying 

rhyolite exposed below mine tunnels. 

R. W. Imlay, and H. C. Brooks, 1962. From cut on road up North Fork of Dennett

Creek near junction with road up main Dennett Creek just below abandoned mining 

town of Mineral near center of SW%NW% sec. 9, T. 14 N., R. 6 W., Washington 

County, Idaho. Unnamed beds. 

R. W. Imlay, 1958. Black concretions in SWtfNWtfSEtf sec. 14, T. 17 S., R. 28 E.,

Grant County, Oreg. Snowshoe Formation. Estimated 3,000-3,500 ft above 

base in area of complex minor folding. 

W. R. Dickinson and R. W. Imlay, 1957. From black concretions about 500-750 ft

northeast of road on divide between Antelope Creek and Rosebud Creek in S}iiSW^ 

sec. 14, T. 17 S., R. 28 E., Grant County, Oreg. Snowshoe Formation. Estimated 

3,000-3,500 ft above base in area of complex minor folds. Poorly exposed. 

W. R. Dickinson and R. W. Imlay, 1957. Black concretions on hillside about 600 ft

north of Mesozoic loc. 26778. Snowshoe Formation. Estimated 3,000-3,500 ft 

above base. Poorly exposed.

mouth of Caps Creek in SW#NWtfSW# sec. 15, T. 17 S., R. 28 E., Grant County, 

Oreg. Snowshoe Formation. Estimated 2,500-3,000 ft above base in area of 

complex minor folding. Poorly exposed.

old farm house in NE. cor. sec. 21, T. 17 S., R. 28 E., Grant County, Oreg. Snowshoe Formation, near top. Estimated 2,500-3,000 ft above base in area of complex 

minor folding.

of Emil Hyde ranch house in SE. cor. NW# sec. 27, T. 17 S., R. 28 E., Grant County, 

Oreg. Lonesome Formation, 1,250-1,500 ft above base.
D12 CONTRIBUTIONS TO PALEONTOLOGY

Descriptions of upper Jurassic fossil localities in east-central Oregon and western Idaho Continued

No. on figs. 1-3

Geological 

Survey 

Mesozoic 

localities

Collector's 

field numbers

Collector, year of collection, description of locality, and stratigraphic assignment

10.

26781

27372

F123(l-44-l).

I58-9-1B.

11 F124(3-44-3) 

of Dickinson.

13.

14. 

14.

14. 

14.

14.

14. 

14.

14.

15.

16.

17.

18.

19. 

19.

27373

27383 158-9-13.

129a.

129b.

130.

131.

132.

139.

26780

28376

28668

28667

28666

28377

F121 (8-10-1 and

8-10-2) of

Dickinson. 

F122 (8-10-3) of

Dickinson. 

DDV (4-82-20)__.

B-94. ..__.___.

B-87-

B-87.

W. R. Dickinson, 1957. Interbedded massive graywacke and black mudstone on 

west bank of South Fork of John Day River about 3,000 ft southeast of mouth of 

Antelope Creek in SW^SW^ sec. 34, T. 17 S., R. 28 E., Grant County, Oreg. 

Lonesome Formation, about 4,000 ft above base.

R. W. Imlay and Reed Christner, 1958. Roadcut near bend in South Fork of John 

Day River about 1 mile below mouth of Antelope Creek in SW. cor. sec. 34, T. 17 S., 

R. 28 E., Grant County, Oreg. Lonesome Formation, near middle of sequence 

exposed between Antelope Creek and Lewis Creek, about 4,000 ft above base of 

formation.

L. W. Vigrass, 1956. On the crest of highest hill near north edge of the NE% sec. 3, 

T. 18 S., R. 28 E., Grant County, Oreg. Lonesome Formation, about 7,000 ft 

above base.

R. W. Imlay and Reed Christner, 1958. Near beginning of big bend in South Fork 

of John Day River, south-central part of NWJ4 sec. 3, T. 18 S., R. 28 E., Grant 

County, Oreg. Lonesome Formation, about 8,000 ft above base and about 1,500 

ft below highest beds in Lonesome syncline.

R. W. Imlay, 1958. On road up hill from the South Fork road to the Old Borg Ranch 

about 300 ft below top of ridge marked by trough of the Lonesome syncline. Eastcentral part of sec. 3, T. 18 S., R. 28 E., Grant County, Oreg. Lonesome Formation, 

near top of sequence exposed between Antelope Creek and Lewis Creek, about 

9,500 ft above base of formation.

R. L. Lupher, 1930. On north side of Flat Creek above mouth of Spoon Creek and 

about 200 ft above creek level. Probably a little east of center of sec. 15, T. 18 S., 

R. 27 E., Grant County, Oreg. Trowbridge Formation, estimated 1,000-1,250 ft 

above base.

R. L. Lupher, 1937. Probably same as loc. 129a. Location is 800 ft upstream from 

junction of Flat Creek and the main tributary along north side of a prominent ridge 

in the Spoon Creek basin. This tributary is separated from Spoon Creek by a small 

gully and a fairly large gully. Trowbridge Formation, lower part. Estimated 

1,000-1,250 ft above base.

R. L. Lupher, 1937. From next spur east of loc. 129b. Trowbridge Formation, 

higher than loc. 129b. Estimated 1,500 ft above base of formation.

R. L. Lupher, 1937. North side of Flat Creek about midway between loc. I29b and 

first main tributary of Flat Creek that comes in from the west below Big Flat. 

Trowbridge Formation, probably near middle. Estimated 1,500 ft above base of 

formation.

R. L. Lupher, 1937. Next gully to northwest of loc. 131. Trowbridge Formation, 

lower part, about 300 ft stratigraphically below green sandstone that overlies concretionary shale. Estimated 1,250 ft above base of formation.

R. L. Lupher, 1937. Near top of shale exposures on north side of Flat Creek at 

either loc. 131 or 132. Trowbridge Formation.

S. W. Muller, R. W. Imlay, W. R. Dickinson, L. W. Vigrass, John Beeson, 1956. On 

slope north of Flat Creek near center of sec. 15, T. 18 S., R. 27 E., Grant County, 

Oreg. Trowbridge Formation, about 1,000 ft above base.

S. W. Muller and others, 1956. Near loc. F121 described above. Estimated 1,250 

ft above base of Trowbridge Formation.

John Beeson, 1957. About half a mile south of Flat Creek in SW% sec. 18, T. 18 S., 

R. 28 E., Grant County, Oreg. Lonesome Formation.

Marvin Beeson, Richard Bateman, and R. W. Imlay, 1961. South side of road near 

junction of Bear Creek and a small tributary. In NWJ4NWJ4 sec. 4, T. 19 S., 

R. 29 E., Sawtooth Creek quadrangle. Harney County, Oreg. Lonesome Formation, 

near top.

Marvin Beeson, 1959. Center of NE. cor. sec. 16, T. 19 S., R. 28 E., Sawtooth Creek 

quadrangle, Harney County, Oreg. Lonesome Formation.

Marvin Beeson, 1959. On road from Sawtooth Creek to Yellowjacket Creek in SE. 

cor. sec. 25, T. 19 S., R. 28 E., Sawtooth Creek quadrangle, Harney County, Oreg. 

Lonesome Formation, near middle.

Marvin Beeson and R. L. Bateman, 1959. Light colored tuff near Sawtooth Creek 

in SEKNWJ4 sec. 13, T. 20 S., R. 28 E., Sawtooth Creek quadrangle, Harney County, 

Oreg. Lonesome Formation, near middle of lower third.

Marvin Beeson, 1960. On east side of Sawtooth Creek in center of sec. 13, T. 20 S., 

R. 28 E., Sawtooth Creek quadrangle, Harney County, Oreg. Lonesome Formation.
UPPER JURASSIC MOLLUSKS FROM OREGON AND IDAHO D13

SYSTEMATIC DESCRIPTIONS

Family OSTREIDAE Lamarck 

Genus OSTREA Linne, 1758

Ostrea sp.

The genus Ostrea is represented by 20 fragmentary 

specimens from the upper part of the Snowshoe Formation. Most of them are small and all are nondescript. 

All were obtained from concretions and most of them 

were attached to molds of ammonites. It seems 

probable that the ammonites or the concretions served 

as relatively hard objects on the sea floor on which the 

spat of oysters could start to grow.

Occurrences: Showshoe Formation, upper part, at USGS 

Mesozoic Iocs. 26778, 27368, and 27369.

Genus GBYPHAEA Lamarck, 1801

Gryphaea culebra Imlay, n. sp.

Plate 1, figures 1-21

The species is represented in the Geological Survey 

collections by 48 specimens from Dennett Creek, Idaho.

The outline of the shell is elongate ovate on the young 

but becomes trigonal on the largest specimens. The 

height exceeds the length but becomes relatively shorter 

during growth. The left valve is strongly convex, its 

umbone is strongly incurved, and its beak is deflected 

posteriorly. The posterior margin is concave and is 

generally extended basally. The anterior margin is 

also concave but less so than the posterior. Most 

left valves bear both posterior and anterior sulci that 

delimit narrow posterior and anterior lobes. Generally 

the posterior sulcus is deeper than the anterior sulcus 

and develops earlier. On a few left valves the anterior 

sulcus is deeper than the posterior sulcus. On still 

other left valves the anterior sulcus is very weak. The 

surface is marked by weak growth lamellae that bend 

dorsally where they cross the sulci. In addition 

several specimens bear weak radial striae on the umbones. The right valve is slightly concave, subovate 

in outline, and bears fine growth lamellae.

The dimensions in millimeters of several specimens 

are as follows:

Specimen

Holotype USNM 132346.. _____

Paratype USNM 132348. ______

Paratype USNM 132356. ______

Length

38

34

33

Height

43

44

44

Inflation of 

left valve

17

20

19

The Idaho species is characterized by its left 

valve developing both posterior and anterior sulci, a 

trigonal outline, concave posterior and anterior margins, 

an extension of the basal margin posteriorly, and in

some shells, an extension of the basil margin anteriorly.

The specimens bearing the weakest anterior sulcus 

have some resemblance to the European Bajocian 

species Gryphaea calceola Quenstedt (1858, pi. 48, figs. 

1-3) but are much shorter and are trigonal rather than 

ovate in outline. Some South American specimens 

that have been compared or referred to 0. calceola 

Quenstedt (Gottsche, 1878, pi. 5, figs. 17 a, b, 18 a-c; 

Burckhardt, 1900, pi. 22, figs. 14-16; Weaver, 1931, 

pi. 19, fig. 93) have a very weak anterior sulcus on the 

left valve, but this sulcus is much less developed than in 

the Oregon species. Also, the shape of the South 

American specimens is elongate ovate, as in European 

specimens of 0. calceola (Quenstedt).

Well-developed anterior and posterior sulci as on the 

Idaho species are found on several South American 

Jurassic species (Gottsche, 1878, pi. 4, figs. 12a, b; 

Phillipe, 1899, pi. 5, figs. 2a-c, 3) of Bajocian to 

Callovian age but all differ from the Oregon species by 

having a sharp umbonal ridge instead of a rounded 

umbone.

Gryphaea nebrascensis Meek and Hayden (Imlay, 

1949, pi. 5, figs. 7, 8), from Callovian beds in the western 

interior of North America, differs from the Oregon 

species by its much more elongate shape, narrower 

umbones, more strongly incurved beak, and generally 

by an absence of a sulcus on the anterior side of the left 

valve. Examination of hundreds of specimens resulted 

in the discovery of only one specimen that had an 

incipient anterior sulcus.

The Idaho species was once considered by J. B. 

Reeside, Jr., to belong to the group of Gryphaea arcuata 

Lamarck (written communication to W. R. Wagner 

dated Sept. 26, 1945) and was the basis for a probable 

Early Jurassic age assignment (McKee and others, 

1956, p. 2). It differs from G. arcuata sharply, however, by having an anterior sutcus as well as a posterior 

sulcus, by being short and trigonal in outline instead of 

elongate-ovate, by being less inflated, and by its beak 

being less incurved.

Types: Holotype USNM 132346; paratypes USNM 132347- 

132356.

Occurrences: USGS Mesozoic loc. 27582 from sandy tuffaceous 

beds on east side of North Fork of Dennett Creek in NE>£NW>£ 

sec. 9, T. 14 N., R. 6 W., Washington County, Idaho; Livingston's 

loc. 88 and Mesozoic loc. 20389 are from the canyon of Dennett 

Creek and probably from the same place as Mesozoic loc. 27582.

Family POSIDONIIDAE Frech, 1909 

Genus POSIDONIA Bronn, 1828

Posidonia ornati Quenstedt 

Plate 1, figure 22

(For synonymy see Cox, 1940, Palaeontologia Indica, ser. 9, 

v. 3, pt. 3, p. 103, 104; Imlay, 1963, Jour. Paleontology, v. 37, 

p. 102.)
D14 CONTRIBUTIONS TO PALEONTOLOGY

This species is represented in Oregon by one specimen 

from the upper part of the Snowshoe Formation (USGS 

Mesozoic loc. 26778) and two specimens from the Lonesome Formation (USGS Mesozoic loc. 28666).

Family MACROCEPHALHTDAE Buckman, 1922 

Genus XENOCEPHALITES Spath, 1928

Xenocephalites vicarius Imlay 

Plate 1, figures 23-27

Xenocephalites vicarius Imlay, 1953b, U.S. Geol. Survey Prof. 

Paper 249-B, p. 78, 79, pi. 28, figs. 1-8.

This species is characterized by being moderately 

compressed for the genus and by its ribbing coarsening 

markedly on the adult body whorl. On the inner 

whorls the ribbing is fine dense and nearly radial. On 

the body whorl the ribs become high, widely spaced, 

thick ventrally, strongly flexuous on the flanks, and 

arched forward gently on the venter.

The species is represented by 4 specimens from near 

Mineral, Idaho, and 27 specimens from east-central 

Oregon.

Types: plesiotypes USNM 132358; plesiotypes GAS 12543- 

12545.

Occurrences: Lonesome Formation, USGS Mesozoic loc. 28376 

and W. R. Dickinson's loc. F 124. Upper part of Snowshoe 

Formation at USGS Mesozoic loc. 26778, Oregon. Unnamed 

beds at Livingston's loc. 88 near Mineral, Idaho. The species 

is probably represented in the Lonesome Formation, Oregon, at 

USGS Mesozoic Iocs. 26782 and 28666 and in unnamed beds 

near Mineral, Idaho, at USGS Mesozoic loc. 28651 (pi. 1, fig. 28). 

In addition the Lonesome Formation along the South Fork of 

the John Day River has furnished fragmentary macrocephalitid 

ammonites, probably belonging to Xenocephalites, at Mesozoic 

Iocs. 26781, 27372, 27373 and 27383. The lower part of the 

Trowbridge Formation near Flat Creek in east-central Oregon 

has furnished fragments referred questionably to Xenocephalites 

at Lupher's Iocs. 129b and 132.

Genus LILLOETTTA Crickmay, 1930 

Lilloettia buckmani Crickmay 

Plate 2, figures 14, 15, 17, 18

Buckmaniceras buckmani Crickmay, 1930, Canada Natl. Mus.

Bull. 63, p. 62, pis. 20, figs. 1-4, text fig. 7. 

Lilloettia buckmani (Crickmay). Imlay, 1953b, U.S. Geol.

Survey Prof. Paper. 249-B, p. 75, pi. 27, figs. 1-9.

This species has the coarsest ribbing of any described 

species of Lilloettia and, next to L. milleri Imlay 

(1935b, p. 75, pi. 28, figs. 11, 13-15, pi. 29, figs. 14, 15), 

is the most inflated. It is represented by five specimens 

from near Mineral, Idaho and five specimens from 

east-central Oregon.

Types: plesiotypes GAS 12540, 12541.

Occurrences: Trowbridge Formation; Lupher's Iocs. 129a, 139 

and Dickinson's loc. F 121(8-10-2), Oregon. Unnamed beds at 

Livingston's loc. 88 near Mineral, Idaho.

Lilloettia cf. I. mertonyarwoodi (Crickmay) 

Plate 2, figures 19, 20

Eight small specimens bear fine closely spaced 

ribbing similar to that on the immature whorls of 

Lilloettia mertonyarwoodi Crickmay (1930, p. 62, pi. 19, 

figs. 1, 2; Imlay, 1953b, p. 76, pi. 30, figs. 3, 5-7, 9-11) 

and L. lilloetensis Crickmay (1930, p. 62, pi. 18, figs. 

1-4; Imlay 1953b, p. 77, pi. 30, figs. 1, 2, 4, 8). The 

largest specimen has a fairly stout whorl section, a 

narrowly arched venter, and converging flanks as in 

L mertonyarwoodi Crickmay.

Figured specimen: GAS 12542.

Occurrence: Trowbridge Formation, Lupher's Iocs. 130, 131, 

Oregon. Unnamed beds, Livingston's loc. 88, near Mineral, 

Idaho.

Lilloettia cf. L. stantoni Imlay

Plate 2, figures 13, 16

A dozen specimens from one spot in the Lonesome 

Formation are compared with Lilloettia stantoni 

Imlay (1953b, p. 77, pi. 29, figs. 1-5, 9, 10) rather 

L. buckmani (Crickmay) (1930, p. 62, pi. 20, figs. 1-4) 

because of their compressed whorl section and because 

the septate whorls bear high thin ribs that persist on 

the lower part of the flanks as far as the adapical end 

of the body chamber.

Figured specimen: USNM 132365.

Occurrence: Lonesome Formation, USGS Mesozoic loc. 28376, 

Oregon.

Family KOSMOCERATTDAE Haug, 1887

Genus KEPPLERITES Neumayr and Uhlig, 1892

Subgenus GOWERICERAS Buckman, 1921

Kepplerites (Gowericeras) cf. K. (G.) torrensi (McLearn)

Plate 3, figures 1-6, 10

Cf. Yakouniceras torrensi McLearn, 1929, Canada Natl. Mus. 

Bull. 54, p. 10, pi. 8, figs. 3, 4.

The species is represented by five septate molds that 

retain considerable shell material. The shell is stout 

and becomes stouter during growth. The coiling is 

moderately evolute. The whorls are depressed ovate 

in section, wider than high, and embrace about twothirds of the preceding whorls. On the smallest specimen available, the flanks and venter are fairly evenly 

rounded, but during growth the venter becomes 

broader and flatter and the flanks become more convex. 

The umbilicus is moderately wide. The umbilical 

wall is moderately high, vertical at base, and rounds 

rapidly into the flanks. The body chamber is not 

preserved.

The small inner whorls, partly exposed in the umbilicus, bear prominent moderately spaced primary ribs 

that incline forward and terminate in conical tubercles 

just below the line of involution. On the larger septate
UPPER JURASSIC MOLLUSKS FROM OREGON AND IDAHO D15

whorls the primary ribs gradually become stronger 

and more widely spaced adorally. The tubercles, 

situated at about one-third of the height of the flanks, 

likewise gradually become stronger adorally. From 

the tubercles on the smallest specimen (pi. 3, fig. 5) 

arise two or three sharp secondary ribs that are a little 

weaker than the primary ribs and that incline slightly 

forward. On the larger specimens the secondary ribs 

generally arise in bundles of three. In addition many 

rib bundles are separated by single intercalated ribs 

that arise near the row of tuberculation. The ribbing 

is reduced in strength along the midventral line on the 

smallest whorls at diameters less than 40 mm.

The smallest specimen at a diameter of 67 mm has a 

whorl height of 22 mm, a whorl thickness of 31(?) mm, 

and an umbilical width of 19 mm. On the next larger 

specimen the same dimensions are 71, 25, 38, and 27 

mm, respectively. The suture line cannot be traced.

The smallest specimen from Oregon greatly resembles 

the holotype of "Yakounoceras" torrensi McLearn 

(1929, p. 10, pi. 8, figs. 3, 4) from the Queen Charlotte 

Islands in coiling, whorl shape, and ornamentation but, 

at a comparable size, has fewer and more widely spaced 

secondary ribs. It likewise resembles Kepplerites newcombii (Whiteaves) (1900, p. 281, pi. 37, figs. 1, la; 

McLearn, 1929, p. 12, pi. 5, figs. 2-4), but that species 

has a distinctly flattened venter and its tubercles are 

lower on the flanks. Kepplerites (Gowericeras) snugharborensis (Imlay) (1953b, p. 99, pi. 53, fig. 9) from Alaska 

differs from the Oregon specimens in its stronger tubercles and ribs that become more widely spaced during 

growth. K. (Gowericeras) ventrale (Buckman) (1922, 

pi. 288) from England has similar ornamentation but 

differs in its higher whorl section. K. (Gowericeras) 

chillanum (Buckman) (1923, pi. 404) has weaker tubercles and a much smaller umbilicus.

Figured specimens: Stanford Univ. Paleontology No. 9709; 

USNM 132366 a, b.

Occurrences: Snowshoe Formation, upper part, USGS Mesozoic Iocs. 26778 and 27369, Oregon. Trowbridge Formation, 

lower part, Dickinson's loc. F122, Oregon.

Family CAUDIOCERATIDAE Siemiradzki, 1891 

Genus PSEUDOCADOCERAS Buckman, 1918

Pseudocadoceras? sp. juv. 

Plate 2, figures 6-12

Pseudocadoceras is probably represented at two localities in eastern Oregon by about 40 specimens. Of 

these one is an external mold that shows part of the 

venter and flanks (USGS Mesozoic loc. 28667) and is 

not deformed. The others (USGS Mesozoic loc. 26780) 

are small limonitic internal molds that are crushed 

laterally and represent immature growth stages. On 

the best preserved limonitic molds the outer whorl

overlaps about three-fifths of the preceding whorl. 

The ornamentation consists of sharp ribs that begin 

near the umbilical suture, incline forward strongly on 

the flanks, and arch forward on the venter. From 

% to /z l of the ribs bifurcate at about the top of the lower 

third of the flanks. The ribs are sharpest on the lower 

part of the flank and broadest on the upper half of the 

flanks. Constrictions are present on several specimens.

These specimens have a general resemblance to immature specimens of Pseudocadoceras and particularly 

to P. grewingki (Pompeckj) (Imlay, 1953b, p. 93, pi. 

49, figs. 1-12) as shown by the presence of many unbranched ribs. They have a resemblance, also, to 

immature specimens of Cadoceras (Stenocadoceras) such 

as C. (S.) multicostatum Imlay (1953b, p. 90, pi. 44, 

figs. 6-8, 12). The molds that bear constrictions are 

coarser ribbed and more evolute than the others and 

possibly belong to a different genus.

Figured specimens: USNM 132363, 132364.

Occurrence: Snowshoe Formation, upper part, USGS Mesozoic 

loc. 26780. Lonesome Formation at Mesozoic loc. 28667.

Genus CARDIOCERAS Neumayr and Uhlig, 1881 

Cardioceras (Scarburgiceras) martini Reeside

Plate 2, figures 1-5

Cardioceras martini Reeside, 1919, U.S. Geol. Survey Prof. Paper 

118, p. 27, pi. 9, figs. 5-8.

Cardioceras (Anacardioceras) martini Reeside. Maire, 1938, 

Soc. ge"ol. France, Me"m. new ser., v. 15 (M6m. 34), p. 65.

Cardioceras (Scarburgiceras) martini Reeside. Spath, 1939, 

Great Britain Geol. Survey Bull., no. 1, p. 84, 85, 92.

Cardioceras (Scarburgiceras) martini Reeside. Imlay, 1947, 

Am. Assoc. Petroleum Geologists Bull., v. 31, p. 264.

Cardioceras (Scarburgiceras) martini Reeside. Arkell, 1946, 

London, Palaeontographical Soc. p. 306.

Protocardioceras martini (Reeside). Schirardin, 1958, AlsaceLorraine Service Carte Ge"ol. Bull., v. 11, pt. 1, p. 24.

Five small specimens obtained from one spot near 

the Snake River in west-central Idaho agree very well 

in shape, coiling, and style of ribbing with the inner 

whorls of Cardioceras martini Reeside (1919, p. 27, 

pi. 9, figs. 5-8) from the Cook Inlet region, Alaska.

On the Idaho specimens the outer whorl overlaps 

about half of the preceding whorl. The umbilical wall 

is low, vertical at its base, and rounds evenly into the 

flanks. The flanks are flattened and high. The 

venter is pinched and keeled. The ribs are high and 

narrow. The primary ribs incline forward slightly on 

the flanks and about one-third of them bifurcate at or 

a little below the middle of the flanks. The secondary 

ribs are weakest along the zone of the furcation and 

some are indistinctly joined with the primary ribs. 

All secondary ribs are projected forward strongly in 

the ventral region and this projection becomes stronger 

during growth. All secondary ribs weaken near the 

keel but are continuous with prominent serrations on
D16 CONTRIBUTIONS TO PALEONTOLOGY

the keel. One specimen at a diameter of 24 mm has 

38 primary ribs and about 54 secondary ribs. Another 

specimen at a diameter of 22 mm has 34 primary ribs 

and about 56 secondary ribs.

On the outer whorl of the holotype of C. martini 

Reeside the mode of rib branching is irregular. Many 

primary ribs bifurcate a little below the middle of the 

flanks, but many others remain simple. Most of the 

simple unbranched ribs alternate with short ribs that 

arise near the middle of the flanks. In addition in a 

few places the secondary ribs branch above the middle 

of the flanks, resulting in a trifid bundling of ribs. 

This feature according to Arkell (1946, p. 306) is not 

found in any of the Cardioceratid ammonites from 

England. C. martini Reeside was placed by Schirardin 

(1958, p. 24) in a new genus Protocardioceras. That 

assignment is questioned, however, because of the 

presence of many simple unbranched ribs in C. martini, 

whereas Protocardioceras is defined as having very few 

simple ribs.

The small specimens of Cardioceras martini Reeside 

from Idaho resemble the small specimens that Reeside 

(1919, pi. 8, figs. 4-7) referred to C. cordiforme (Meek 

and Hayden) but differ by having finer, straighter, 

and lower primary ribs, a more strongly pinched 

venter, and more unbranched ribs. They show even 

greater resemblance to small specimens of Cardioceras 

bukowskiM&ire (1938, p. 64, pi. 7, fig., 8; Arkell, 1946, 

p. 305, text fig. 108-1) and C. cf. C. reesidei Maire 

(Arkell, 1946, p. 307, text fig. 108-3 to 5 on p. 305) 

from northwest Europe but have less strongly projected ribbing on the venter.

Types: holotype USNM 32317; plesiotypes USNM 132360- 

132362.

Occurrence: Naknek Formation at USGS Mesozoic loc. 8575 

(holotype) and 11017, Alaska. Unnamed beds at USGS 

Mesozoic loc. 28652 in the canyon of the Snake River, Idaho.

Family REINECKEIIDAE Hyatt, 1900

Genus PARAREINECKEIA Imlay, 1962

Parareineckeia cf. P. hickersonensis Imlay

Plate 4, figures 1-6

Cf. Parareineckeia hickersonensis Imlay, 1962a, U.S. Geol. Survey 

Prof. Paper 374-C, p. C-25, pi. 7, figs. 1-6.

One small ammonite from eastern Oregon greatly 

resembles the inner whorls of Parareineckeia hickersonensis Imlay. It differs mainly by being more 

coronate and by its lateral tubercles not being alternately weak and strong. It has strongly divergent 

flanks and a broad depressed venter. Its primary 

ribs are narrow, widely spaced, incline gently forward 

on the flanks, and terminate at the top of the flanks in 

prominent round tubercles of variable strength. From

the tubercles on the outermost whorl arise two or three 

ribs, or rarely single ribs that arch forward slightly on 

the venter and are reduced in strength along the 

midline of the venter. From the tubercles on the next 

smallest whorl arise three to four secondary ribs. 

These cross the venter nearly transversely and are 

distinctly reduced in strength along the midline.

Figured specimens: USNM 132368.

Occurrence: Snowshoe Formation, upper part, USGS Mesozoic, 

loc. 26778, Oregon.

Family PERISPHINCTIDAE Steinmann, 1890

Genus COBBANTTES Imlay, 1962 

Cobbanites aff. C. talkeetnanus Imlay

Plate 4, figures 10-13

The genus Cobbanites is represented in the upper 

part of the Snowshoe Formation, Oregon, by four 

septate specimens. The whorls are subovate in section, 

a little wider than high and each whorl embraces about 

two-fifths of the preceding whorl. The flanks are 

gently convex and round evenly into the umbilical 

wall and into the venter. The umbilicus is very wide 

and shallow; the umbilical wall is low and steeply 

inclined at its base. The body chamber is u'nknown.

On the smallest whorls that are preserved (pi. 4, figs. 

8, 9), the primary ribs are high, sharp, fairly regularly 

spaced and are separated by interspaces that are 

slightly wider than the ribs. They begin near the 

umbilical seam, incline forward on the flanks, and most 

of them bifurcate near the middle of the flanks. The 

secondary ribs are a little weaker than the primary 

ribs, curve forward on the flanks, and arch forward 

gently on the venter. Each whorl bears from five to 

six deep constrictions that incline forward strongly and 

that are generally bounded by swollen ribs. On whorls 

at diameters of less than 45 mm the furcation points of 

the ribs are swollen or weakly tuberculate.

During growth the ribs become weaker, more widely 

spaced, and less strongly projected forward. On the 

largest whorl available, the primary ribs are weak and 

fairly widely spaced. The venter, well exposed only 

on one specimen, is marked by weakening of the ribs 

along the mid ventral line.

The suture line on one specimen is represented by a 

long, slender irregularly trifid first lateral lobe and part 

of a retracted suspensive lobe.

This Oregon species differs from Cobbanites talkeetnanus Imlay (1962a, p. C-27) from Alaska by having a 

rounder wider whorl section and somewhat coarser 

ribbing on its inner septate whorls. Its ribbing compares in coarseness with that of a species of Cobbanites, 

described as Procerites sp. (Imlay, 1953b, p. 102, pi. 53, 

figs. 1-3), from the Chinitna formation of Alaska, and
UPPER JURASSIC MOLLUSKS FROM OREGON AND IDAHO D17

it could belong to that species. "Procerites" sp. from 

the Kierdon formation of Montana (Imlay, 1953a, p. 33, 

pi. 23, figs 13, 17, pi. 24, figs. 9-11) differs from the 

Oregon species in its much coarser ribbing and its 

higher subquadrate whorl section. Cobbanites engleri 

(Frebold) (1957, p. 65, pi. 39, fig. 1, pi. 40, figs, la, b) 

from Canada has much finer denser ribbing and a more 

compressed whorl section.

Figured specimens: USNM 132371 a, b.

Occurrence: Snowshoe Formation, upper part, USGS Mesozoic 

loc. 26778 and 27369, Oregon.

Cobbanites sp. juv. 

Plate 4, figures 7-9

A few small immature specimens of Cobbanites occur 

in the Lonesome Formation in Oregon and in some 

Jurassic shale near Mineral, Idaho. These ammonites 

have sharp closely spaced prorsiradiate primary ribs 

that bifurcate at or just above the middle of the flanks 

into slightly weaker forwardly inclined secondary 

ribs. The furcation points are marked by tiny tubercles, or swellings. Each whorl has several deeply 

impressed constrictions that project strongly forward.

Figured specimens: USNM 132369, 132370.

Occurrences: Lonesome Formation, USGS Mesozoic loc. 28666, 

Oregon. Unnamed shale at USGS Mesozoic loc. 28651 near 

Mineral, Idaho.

Genus CHOFFATIA Siemiradzki 1898

Choffatia (Loboplanulites) cf. C. (I.) cerealis Arkell

Plate 3, ngures 7-9

The genus Choffatia is represented in eastern Oregon 

by four fragmentary specimens. The whorl section, 

preserved only on the largest fragment, is subovate 

and is wider than high. The coiling is fairly evolute. 

The primary ribs are prominent, widely spaced, curve 

backward on the umbilical wall, and then curve forward 

to near the middle of the flanks. From each primary 

rib arises two much weaker secondary ribs. In addition one or two weak secondary ribs arise between 

successive forked ribs at or above the zone of furcation. 

All secondary ribs project forward on the flanks and 

arch forward gently on the venter. On the adoral end 

of the largest specimen the secondary ribs are reduced 

slightly in strength along the midventral line. Each 

fragment bears one deeply impressed forwardly inclined 

constriction. The largest specimen near its adoral end 

has a whorl height of 47 mm and a whorl thickness of 

54 mm.

These specimens are assigned to Choffatia because 

of their evolute coiling, long strong widely spaced 

primary ribs, much weaker forwardly arched secondary 

ribs, and deep constrictions (see generic diagnosis by 

Spath, 1931, p. 281, 325, and Arkell, 1958, p. 211).

The genus Subgrossouvria Spath (1924, p. 13; 1931, 

p. 327) has finer less differentiated ribbing on its inner 

whorls and coarser more distant primary ribs on its 

outer whorls. These features are shown on species of 

Choffatia from southern Mexico described by Burckhardt (1927, pi. 30, figs. 6, 7, pi. 31, figs. 1-7 pi. 33, 

figs. 1-3).

The larger specimen of Choffatia illustrated herein 

has ornamentation similar to that on the larger outer 

whorl of Chojfatia subbakeriae (d'Orbigny) (1846, p. 

148; Arkell, 1958, p. 215, pi. 30, fig. 2) but has a stouter 

whorl section and its primary ribs are stronger and 

sparser. In these respects it shows greater resemblance 

to C. (Loboplanulites) cerealis Arkell (1958, p. 219, 

pi. 31, figs. 4-6), differing apparently by having a 

more depressed whorl section and somewhat sharper 

ribbing. C. (Loboplanulites) recuperoi (Gemmellaro), 

as figured by Arkell (1958, p. 221, text fig. 80-la, b), 

differs from the Oregon species by having less projected 

denser ribbing and apparently more evolute coiling. 

C. recuperoi (Gemmellaro), as figured by Sayn and 

Roman (1930, p. 181, pi. 16, fig. 5, pi. 17, figs. 2, 3, 

pi. 18, fig. 1), resembles the Oregon species in ribbing 

but is more evolute. Among American species, both 

Chojfatia irregularis (Imlay) (1953b, p. 102, pi. 54; 

Arkell, 1956, p. 536) from Alaska and C. hyatti (Crickmay) (1933, p. 913, pi. 32, fig. 3, pi. 33) from California 

have much longer, weaker, and more closely spaced 

primary ribs and more evolute coiling.

Figured specimens: USNM 132367 a, b. 

Occurrence: Snowshoe Formation, upper part, at USGS 

Mesozoic loc. 26778, Oregon.

LITERATURE CITED

Arkell, W. J., 1935-48, A monograph of the ammonites of the

English Corallian beds: London, Palaeontographical Soc.,

i-lxxxiv, 420 p., 77 pis., 138 text figs. 

 1951-58, Monograph of English Bathonian ammonites:

London, Palaeontographical Soc., i-viii, 264 p., 33 pis., 83

text figs.

1956, Jurassic geology of the world: London, Oliver and

Boyd Ltd., 806 p., 46 pis., 28 tables, 102 figs. 

Bohm, Johannes, 1903, Uber die obertriadische Fauna de Bareninsel: K. Svenska Vetensk. Akad. Handl., v. 37, no. 3,

76 p., 7 pis. 

Buckman, S. S., 1909-30, [Yorkshire] Type ammonites: London,

Weldon and Wesley Ltd., 7 v. 

Burckhardt, Carl, 1900, Profils geologiques transversaux de la

Cordillere argentino-chilienne, stratigraphie et tectonique:

Museo de La Plata Anales, Sec. geol. y min., v. 2, 136 p.,

32 pis. 

 1927 Cefal6podes del Jurasico medio de Oaxaca y Guerrero: Mexico Inst. geol. Bol., no. 47, 108 p., 34 pis. 

Callomon, J. H., 1955, The ammonite succession in the Lower

Oxford clay and Kellaways beds at Kidlington, Oxfordshire,

and the zones of the Callovian stage: Royal Soc. London

Philos. Trans., v. 239, p. 215-264, pis. 2 and 3, figs., 4 tables.
D18 CONTRIBUTIONS TO PALEONTOLOGY

Callomon, J. H., 1959, The ammonite zones of the Middle Jurassic beds of East Greenland: Geol. Mag., v. 96, no. 6, p.

505-513, pis. 17, 18. 

Cox, L. R., 1940, The Jurassic lamellibranch fauna of Cutch

(Kachh): India Geol. Survey Mem., Palaeontologica Indica,

ser. 9, v. 3, pt. 3, p. 1-157, pis. 1-10.

 1952, The Jurassic lamellibranch fauna of Cutch (Kachh) 

No. 3, Families Pectinidae, Amusiidae, Plicatulidae, Limidae, Ostreidae and Trigoniidae (Supplement): India Geol. 

Survey Mem., Palaeontologia Indica, ser. 9, v. 3, pt. 4, 

p. 1-128, pis. 1-12.

Crickmay, C. H., 1930, Fossils from Harrison Lake area, British 

Columbia: Canada Natl. Mus. Bull. 63, p. 33-66, 82-113, 

pis. 8-23.

 1933, Mount Jura investigation: Geol. Soc. America

Bull., v. 44, p. 895-926, pis. 23-34. 

Dickinson, W. R., 1962a, Metasomatic quartz keratophyre in

central Oregon: Am. Jour. Sci., v. 260, p. 249-266, 5 text

figs., 3 tables.

 1962b, Petrology and diagenesis of Jurassic andesitic 

strata in central Oregon: Am. Jour. Sci., v. 260, p. 481-500.

Frebold, Hans, 1951, Geologic des Barentsschelves: Deutsch. 

Akad. Wiss. Berlin Abh., Kl. Math.-naturwiss. Jahrg. 

1950, no. 5, 151 p., 82 figs.

 1953, Correlation of the Jurassic formations of Canada: 

Geol. Soc. America Bull., v. 64, p. 1229-1246, 1 fig., 1 correlation chart.

 1957, The Jurassic Fernie group in the Canadian Rocky

Mountains and foothills: Canada Geol. Survey Mem. 287,

197 p., 44 pis., 5 figs. 

Frebold, Hans, Mountjoy, E., and Reed, Ruth, 1959, The

Jurassic beds of the Jurassic Fernie group, Alberta and

British Columbia: Canada Geol. Survey Bull. 53, 47 p.,

pis. 1-12, 6 figs. 

Gottsche, Carl, 1878, Uber jurassische Versteinerungen aus der

argentinischen Cordillere: Palaeontographica, supp. 3, Lief.

2, Abt. 3, p. 1-50, pis. 1-8. 

Imlay, R. W., 1947, Marine Jurassic of Black Hills area, South

Dakota and Wyoming: Am. Assoc. Petroleum Geologists

Bull, v. 31, p. 227-273, 3 figs.

 1949, Characteristic marine Jurassic fossils from the 

western interior of the United States: U.S. Geol. Survey 

Prof. Paper 214-B, p. 13-25, pis. 5-9.

 1952, Correlation of the Jurassic formations of North 

America, exclusive of Canada: Geol. Soc. America Bull., 

v. 63, p. 953-992, 2 correlation charts.

 1953a, Callovian (Jurassic) ammonites from the United 

States and Alaska, Part 1. Western interior United States: 

U.S. Geol. Survey Prof. Paper 249-A, p. 1-39, pis. 1-24, 

2 text figs., 3 tables.

 1953b, Callovian (Jurassic) ammonites from the United 

States and Alaska, Part 2. Alaska Peninsula and Cook Inlet 

regions: U.S. Geol. Survey Prof. Paper 249-B, p. 41-108, 

pis. 25-55, 7 text figs., 6 tables.

 1956, Marine Jurassic exposed in Bighorn Basin, Pryor 

and Northern Bighorn Mountains, Wyoming and Montana: 

Am. Assoc. Petroleum Geologists Bull., v. 40, p. 562-599, 

7 figs.

 1957, Paleoecology of Jurassic seas in the western interior 

of the United States, in Ladd, H. S., ed., Paleoecology: 

Geol. Soc. America Mem. 67, p. 469-504, 8 figs.

 1959, History of Jurassic sedimentation in the Pacific 

Coast region: Oregon Dept. Geol. and Mineral Industries 

Bull. 50, p. 103-106.

Imlay, R. W., 1961, Late Jurassic ammonites from the western 

Sierra Nevada, California: U.S. Geol. Survey Prof. Paper 

374-D, p. D-l D-30, pis. 1-6, 3 figs.

 1962a, Jurassic (Bathonian or Early Callovian) ammonites from Alaska and Montana: U.S. Geol. Survey Prof. 

Paper 374-C, p. C-l C-32, pis. 1-8, 7 text figs., 6 tables.

 1962b, Late Bajocian ammonites from the Cook Inlet 

region, Alaska: U.S. Geol. Survey Prof. Paper 418-A, p. 

A-l A-15, pis. 1-5, 4 figs.

1963, Jurassic fossils from southern California: Jour.

Paleontology, v. 37, p. 97-107, pi. 14. 

Imlay, R. W., Gardner, L. S., Rogers, C. P., Jr., and Hadley,

H. D., 1948, Marine Jurassic formations of Montana: U.S.

Geol. Survey Oil and Gas Inv. Prelim. Chart 32. 

Livingston, D. C., 1932, A major overthrust in western Idaho and

northeastern Oregon: Northwest Sci., v. 6, no. 2, p. 31-36. 

Lupher, R. L., 1941, Jurassic stratigraphy of central Oregon:

Geol. Soc. America Bull., v. 52, p. 219-270, 4 pis., 3 figs. 

McKee, E. D., and others, 1956, Paleotectonic maps of the

Jurassic system. With a separate section on paleogeography, by R. W. Imlay: U.S. Geol. Survey Misc. Geol.

Inv. Map 1-175, 6 p. 9 pis., 5 figs. 2 charts. 

McLearn, F. H., 1929, Contributions to the stratigraphy and

paleontology of Skidgate Inlet, Queen Charlotte Islands,

British Columbia: Canada Natl. Mus. Bull. 54, Geol. Ser.,

no. 49, p. 1-27, 16 pis. 

Maire, Victor, 1938, Contribution & la connaissance des Cardioce'ratides: Soc. geol. France Me"m., new ser., v. 15, (M&n.

34), 134 p., pis. 5-24. 

Morrison, R. F., 1961, Angular unconformity marks TriassicJurassic boundary in Snake River area of northeastern

Oregon: The Ore Bin, v. 23, no. 11, p. 105-111, illust. 

Orbigny, Alcide d', 1842-51, Paleontologie franchise: Terrains

Jurassiques, v. 1, Ce'phalapods: Paris, Masson. 

Phillipi, R. A., 1899, Los fosiles secundarios de Chile: Santiago,

Chile, 104 p., 42 pis., (Published by the government of

Chile). 

Quenstedt, F. A. von, 1858, Der Jura: Tubingen, 842 p., atlas of

100 pis. 

Reeside, J. B., Jr., 1919, Some American Jurassic ammonites

of the genera Quenstedticeras, Cardioceras, and Amoeboceras,

family Cardioceratidae: U.S. Geol. Survey Prof. Paper 118,

p. 3-64. pis. 1-24, 1 text fig. 

Sayn, G. and Roman, Frederic, 1928-1930, Monographic stratigraphique et pal^ontologique du Jurassique moyen de la

Voulte-sur-Rhone: Lyon Univ. Lab. geologic Travaux, fasc.

13, 14 (Mem. 11), 256 p., 21 pis. 

Scalia, S., 1912, La fauna del Trias superiore del gruppo di

Monte Judica: Accad. gioenia Sci. Nat. Catania, Atti, ser.

5, v. 5, Mem. 8, p. 1-58, pis. 1-3. 

Schirardin, Jules, 1957-58, Les ammonites de 1'Oxfordien du

Jura Alsacien de la region de Ferrette: Alsace-Lorraine

Service Carte Geol. Bull., v. 10, pt. 2, p. 75-118, pis. 1, 2

(1957), v. 11, pt. 1, p. 3-50, pis. 3-5 (1958). 

Spath, L. F., 1924, On the Blake collection of ammonites from

Kachh, India: India Geol. Survey Mem. Palaeontologia

Indica, new ser., v. 9, mem. 1, p. 1-29.

 1927-33, Revision of the Jurassic cephalopod fauna of 

Kachh (Cutch): India Geol. Survey Mem. Palaeontologia 

Indica, new ser., v. 9, mem. 2, 6 pts., 945 p., 130 pis.

 1932, The invertebrate faunas of the Bathonian-Callovian 

deposits of Jameson Land (East Greenland): Medd. om 

Gr0nland, v. 87, no. 7, 158 p., 26 pis., 14 text figs.
UPPER JURASSIC MOLLUSKS FROM OREGON AND IDAHO D19

Spath, L. F., 1939, The ammonite zones of the upper Oxford

clay of Warboys, Huntingdonshire: Great Britain Geol.

Survey Bull., no. 1, p. 82-98, pis. 6, 7. 

Stehn, E., 1924, Beitrage zar Kenntnis des Bathonian und Callovian in Sudamerika: Neues Jahrb., Beilage-Band 49 for

1923, p. 52-158, 8 pis. 

Weaver, C. E., 1931, Paleontology of the Jurassic and Cretaceous

of west central Argentina: Univ. Washington Mem., v. 1, 

469 p., 62 pis.

Whiteaves, J. F., 1900, On some additional or imperfectly understood fossils from the Cretaceous rocks of the Queen Charlotte Islands, with a revised list of species from these rocks: 

Canada Geol. Survey Mesozoic Fossils, p. 263-307, pis. 

34-39.

INDEX

Page

Ages and correlations_____________ D6

Alaska and western British Columbia____ 10

Ammonites*.___________________ 4

Amoebocems___________________ 6

(Anacardioceras) martini, Cardioceras. __._ 15

arcuata, Oryphaea.......... ...._____ 13

Biologic analysis________________ 2

Bowser Formation._______________ 8,10

Buchia concentrica--.......................... 6

buckmani, Buckmaniceras..................... 14

Lilloettia.. ................. 6,7,9,14; Pi. 2

Buckmaniceras buckmani...................... 14

bukowski, Cardioceras......................... 16

Cadoceras..................................... 8,10

(Stenocadoceras).......................... 15

multicostatum......................... 15

Cadoceratinae_________________ 2 

calceola, Oryphaea............................. 7,13

California..__________________ lo 

Cattiphylloceras............................... 2

sp._.. ............................. 7

Calliphylloceratinae_______________ 2 

Callovian fossils..______________ 4

calloviense zone, Sigaloceras............ ___ lo

Cardioceras............................... 1,6,11, 15

bukowski...________________.. 16 

cordatum.......______________ 6

cordiforme................................ 16

martini................................... 15,16

reesidei................................... 16

(Anacardioceras) martini.................. 15

(Scarburgiceras)........................... 2

martini.................. 6, 7,10,11, 15; pi. 2

Cardocieratid ammonites___..______ 16 

Cardioceratidae._________________ 2,15 

Cardioceratinae._________________ 2 

cerealis, Choffatia (Loboplanulites)....... 7,17; pi. 3

chillanum, Kepplerites (Gowericeras).......... 15

Chinitna Formation____ _ ______.. 6,8,10 

Choffatia.............................. 2, 7, 8, 9,10, 17

hyatti..................................... 17

irregularis................................ 17

recuperoi_..._______________ 17 

subbakeriae............................... 17

(Loboplanulites) cerealis............ 7, /7,-pl. 3

recuperoi.... ...___..______. 17

Cobbanites......................... 2,7,8,9,10,11,18

engleri.................................... 17

talkeetnanus.........,.__.____ 7, 16; pi. 4

sp................................. 6, 7, 9, 17; pi. 4

Colfax Formation of Smith___________ 10 

Comparisons with other faunas___ ___ _ 10 

concentrica, Buchia............................ 6

Conditions of deposition________.... 6

cordatum, Cardioceras......................... 6

cordiforme, Cardioceras........................ 16

Correlations and ages.._____________ 6 

Cranocephalites............................... 8

culebra, Oryphaea.......................... IS; pi. 1

[Italic page numbers indicate major references and descriptions]

Page 

grewingki, Pseudocadoceras.................... D15

Orossouvria................................... 10

Oryphaea.................................. 2,6, 7, IS

arcuata................................... 13

calceola................................... 7, 13

culebra................................. IS; pi. 1

impressimarginata......................_ 8

nebrascensis............................... 8,13

sp_______________________ 7 

Gryphaeas...___________________ 3,6, 7

hickersonensis, Parareineckeia............ 7,16;pL 4

hyatti, Choffatia............................... 17

engleri, Cobbanites. 

Procerites......

17

Foreman Formation. ...................... 10

Geographic distribution..___________ // 

Oowericeras............................... .... 8, 14

(Oowericeras) chillanum, Kepplerites.......... 15

Kepplerites.............................. 2,8,10

snugharborensis, Kepplerites............... 15

torrensi, Kepplerites................ 7,9,14; pi. 3

ventrale, Kepplerites....................... 15

impressimarginata, Oryphaea. 

Introduction_____.... 

irregularis, Choffatia..........

Jurassic black shale.

Kepplerites.................. , 2,7,8,/4

newcombii................................. 15

tychonis zone__ 8 

(Oowericeras)............................ 2,8,10

chillanum............................. 15

snugharborensis................-.-.--- 15

torrensi ...................... 7,9,14; pi. 3

ventrale............................... 15

sp___________________ . 7 

Kosmoceratidae.._ .. . ... 2,14

Lilloettia........................... 2,6,7,8,10,11, 14

buckmani........................ 6,7,9,14; pi. 2

mertonyarwoodi................. 6,7,9,14; pi. 2

milleri.................................... 14

stantoni............................ 7,9,14; pi. 2

sp.__._._..,.__.._._......._ 6, 7,9

Loboplanulites................................ 8

(Loboplanulites) cerealis, Choffatia...... 7,17; pi. 3

recuperoi, Choffatia.................... 17

Logtown Ridge Formation...___.. 10

Lonesome Formation of Lupher.. 4,

6,9,11,12,14,15,17

Lytoceras..................................... 2

sp... --- _-. . . . .--- - 7 

Lytoceratidae...._.. . 2

Lytoceratinae.... 2

Macrocephalites macrocephalus zone 8

Macrocephalitidae..._________ 2,14

macrocephalus zone, Macrocephalites.......... 8

mariae, Quenstedtoceras....................... 6

martini, Cardioceras........................... 15,16

Cardioceras (Anacardioceras}.............. 15

(Scarburgiceras).......... 6, 7,10,11,15; pi. 2

Protocardioceras.....-... ---------------- 15

mertonyarwoodi, Lilloettia- . 6,7, 9,14; Pi- 2

milleri, Lilloettia.............................. 14

Mineral area, western Idaho #

multicostatum, Cadoceras (Stenocadoceras)-.... 15

Mysterious Creek Formation.. 10

Naknek Formation_.-...-..--... 6,16

nebrascensis, Oryphaea........................ 8,13

newcombii, Kepplerites............... --.. . 15

North Ridge Formation of Crickmay.------- 10

Oregon, east-central.---. 4 

northeastern and adjoining Idaho.- 8

ornati, Posidonia.....,............ ,..- 7,9,/3,-pl. 1

Ostrea....................... ............... - 2,13

sp . 7,13

Ostreidae_______._... - 13

Oysters.

Page 

D3.4.6

Parareineckeia........................ 2,7,8,9,10, 16

hickersonensis......................... 7,16; pi. 4

Peltoceras..................................... 10

Perisphinctes plicatilis......................... 6

Perisphinctidae ________.______ 2,16 

Phylloceras..............................._. 2

sp______________.________ 7,9 

Phylloceratidae_______ - -.__ 2 

Phylloceratinae______...... .-..___ 2

plicatilis, Perisphinctes........................ 6

Posidonia.... .. . ....-------------- 2, 4,13

ornati..........._.----. ------.- 7,9, IS; pi. 1

Posidoniidae-- 13

Procerites engleri......-....................... 8

sp.................... ....-. ........... 16,17

Protocardioceras.......... . .............. 16

martini................................... 15

Pseudocadoceras.... 2,10, IB

grewingki.....-------------- 15

sp...... . 7,9, IB; pi. 2

pseudoperisphinctinae 2

Quenstedtoceras mariae.

recuperoi, Choffatia.................... ...... 17

Choffatia (Loboplanulites).... . ...... 17

reesidei, Cardioceras............. .. ........ 16

Reineckeiidae.. . . . . ... 2,16

Sawtooth Formation... 8

Scarburgiceras.... .......................... 6

(Scarburgiceras), Cardioceras.-.. ............ 2

martini, Cardioceras.......... 6,7,10,11, 15; pi. 2

Seymourites....................-..- .-..-.... 8

Shelikof Formation. . 8,10

Sigaloceras calloviense zone.. 10

Snowshoe Formation of Lupher... 4,

6, 7,10,11,13,14,15,16,17

snugharborensis, Kepplerites (Oowericeras)..... 15

stantoni, Lilloettia. . - 7,9,14; Pi. 2

(Stenocadoceras), Cadoceras.......... .. 15

multicostatum, Cadoceras.................. 15

Stratigraphy summary.-- *

subbakeriae, Choffatia...___ .. -- 17

Subgrossouvria....... . .---------------- 17

talkeetnanus, Cobbanites-................. 7, 16; PL 4

torrensi, Kepplerites (Oowericeras)....... 7,9,14; pi. 3

Yakouniceras........ . .- H 15

Trowbridge Formation of Lupher 3,4, 9, 10,14,15 

tychonis zone, Kepplerites .... - --- 8

Unnamed beds, northeastern Oregon and 

adjoining Idaho_ 

near Mineral, Idaho .-- --- 

ventrale, Kepplerites (Oowericeras)........ - 15

vicarius, Xenocephalites. - 6,7,9, lO.J&pl. 1

Western interior of North America. . ------ 10

Xenocephalites. . 2, 6,7,8,10,11, 14 

vicarius...... - 6,7,9,10, U; pi. 1

sp. ......... 7,9

Yakoun Formation W 

Yakouniceras torrensi.................-------- 14,15

Zigzagiceratinae.

D21

PLATES 1-4
PLATE 1

[Figures natural size unless otherwise indicated]

FIGURES 1-21. Gryphaea culebra Imlay, n. sp. (p. D13). 

1-4. Paratype USNM 132348.

5. Paratype USNM 132347 (X 2). Shows radial striae on umbonal

region. 

6-9. Holotype USNM 132346.

10. Paratype USNM 132349.

11. Paratype USNM 132350.

12. Paratype USNM 132351. 

13, 14. Paratype USNM 132352. 

15, 16. Paratype USNM 132353.

17. Paratype USNM 132354.

18. Paratype USNM 132355.

19. Paratype USNM 132356. Shows concave right valve. 

20, 21. Paratype USNM 132357. All specimens shown on figs. 1-21

are from USGS Mesozoic loc. 27582.

22. Posidonia ornati Quenstedt (p. D13). Plesiotype USNM 13129. 

23-27. Xenocephalites vicarius Imlay (p. D14).

23. Plesiotype GAS 12543 from Livingston's loc. 88 near Mineral,

Idaho. Shows adult body whorl.

24, 25. Plesiotype CAS 12544 from Livingston's loc. 88 near Mineral, 

Idaho. Shows most of adult body whorl.

26. Plesiotype USNM 132358 from USGS Mesozoic loc. 26778.

27. Plesiotype CAS 12545 from Livingston's loc. 88 near Mineral,

Idaho. 

28. Xenocephalites cf. X. vicarius Imlay (p. D14).

Figured specimen USNM 132359 (X 2) from USGS Mesozoic loc. 28651.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 483-D PLATE 1

23

GRYPHAEA, POSIDONIA, AND XENOCEPHALITES
PLATE 2

[All figures are natural size]

FIGURES 1-5. Cardioceras (Scarburgiceras) martini Reeside (p. D15).

1. Plesiotype USNM 132360 from USGS Mesozoic loc. 11017, Naknek Formation, lower part on South 

Shore of Chinitna Bay, Cook Inlet region, Alaska. Part of outer whorl has been removed to 

show ribbing on inner septate whorls. Compare with figs. 4 and 5.

2, 3. Holotype USNM 32317 from USGS Mesozoic loc. 8575. Naknek Formation, lower part, near 

lowest outcrop on creek entering Boulder Creek from the northwest 5% miles above the East 

Fork, Talkeetna Mountains, Alaska. Included for comparison with figs. 4 and 5.

4. Plesiotype USNM 132361 from USGS Mesozoic loc. 28652.

5. Plesiotype USNM 132362 from USGS Mesozoic loc. 28652. 

6-12. Pseudocadocerasl sp. juv. (p. D15).

6, 7. Figured specimen USNM 132363 from USGS Mesozoic loc. 28667. Ventral and lateral views of

rubber cast of an external mold.

8-12. Figured specimens USNM 132364 from USGS Mesozoic loc. 26780. Figs. 8-11 are lateral views 

of crushed internal molds. Fig. 12 is from a rubber cast of an external mold of same specimen 

as shown in fig. 11. 

13, 16. Lilloettia cf. L. stantoni Imlay (p. D14).

Figured specimen USNM 132365 from USGS Mesozoic loc. 28376. 

14, 15, 17, 18. Lilloettia buckmani (Crickmay) (p. D14).

14, 15. Plesiotype CAS 12540 from Lupher's loc. 129 A. 

17, 18. Plesiotype CAS 12541 from Lupher's loc. 129 A. 

19, 20. Lilloettia cf. L. mertonyarwoodi Crickmay (p. D14).

Figured specimen CAS 12542 from Livingston's loc. 88 near Mineral, Idaho.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 483-D PLATE 2

17 ^^^ ^^ ^^^ 20

CARDIOCERAS (SCARBURGICERAS), PSEUDOCADOCERAS ?,AND LILLOETTIA

18
PLATE 3

[All figures are natural size]

FIGURES 1-6, 10. Kepplerites (Gowericeras) cf. K. ((?.) torrensi (McLearn) (p. D14).

1, 2. Ventral and lateral views of figured specimens USNM 132366a from USGS Mesozoic loc. 26778. 

3-5. Apertural, ventral, and lateral views of figured specimen Stanford Univ. Museum Paleonotology 9709 

from Dickinson's loc. F 122 (8-10-3).

6. 10. Lateral and ventral views of figured specimen USNM 132366b from USGS Mesozoic loc. 26778. 

7-9. Choffatia (Loboplanulites) cf. C. (L.) cerealis Arkell (p. D17).

7. 8. Ventral and lateral view of large septate whorl. USNM 132367a from USGS Mesozoic loc. 26778. 

9. Lateral view of small septate whorls. USNM 132367b from USGS Mesozoic loc. 26778.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 483-D PLATE 3

10

KEPPLERITES (GOWERICERAS) AND CHOFFATIA (LOBOPLANULITES)
PLATE 4

[Figures are natural size unless otherwise indicated]

FIGURES 1-6. Parareineckeia cf. P. hickersonensis (Imlay) (p. D16).

1, 2. Ventral and lateral views (X2) of figured specimen USNM 132368 from USGS Mesozoic loc. 26778. 

3, 4. Inner whorls (X2) of same specimen shown in figs. 1 and 2. Note ventral groove. 

5, 6. Inner whorls (XI) of same specimen shown in figs. 1 and 2. 

7-9. Cobbanites sp. juv. (p. D17).

7. Lateral view of rubber cast of external mold of specimen USNM 132369 from USGS Mesozoic loc. 28651. 

8, 9. Lateral view (XI and X2) of internal mold of specimen USNM 132370 from USGS Mesozoic loc. 28666. 

10-13. Cobbanites aff. C. talkeetnanus Imlay (p. D16).

10. 12. Figured specimen USNM 13237la from USGS Mesozoic loc. 26778. Fig. 10 is from a rubber cast of 

the external mold. Fig. 12 is an internal mold with some shell adhering.

11. 13. Lateral and ventral views of figured specimen USNM 132371b from USGS Mesozoic loc. 26778.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 483-D PLATE 4

11 ^.99^^^^ 12 

PARAREINECKEIA AND COBBANITES

U.S. GOVERNMENT PRINTING OFFICE : 1964 O - 716-E