Nonmarine Ostracodes of 

Early Cretaceous Age From 

Pine Valley Quadrangle 

Nevada

GEOLOGICAL SURVEY PROFESSIONAL PAPER 643-B
Nonmarine Ostracodes of 

Early Cretaceous Age From 

Pine Valley Quadrangle 

Nevada

By I. G. SOHN

CONTRIBUTIONS TO PALEONTOLOGY

GEOLOGICAL SURVEY PROFESSIONAL PAPER 643-B

Descriptions of two new nonmarine 

ostracode species of Aptian age

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1969
UNITED STATES DEPARTMENT OF THE INTERIOR 

WALTER J. HIGKEL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

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

Washington, D.C. 20402 - Price 35 cents (paper cover)
CONTENTS

Abstract _ _____________________________

Introduction. ____________________________

Acknowledgments__ ________________

Cretaceous sedimentary rocks in Nevada. 

Interpretation of the ostracodes_ _______

Systematic descriptions__________________

Subfamily Cyprideinae________________

Genus Cypridea- _________________

Subgenus Cypridea-___________

Page

Bl 

1 

1

1

2

3

3

4

5

Systematic descriptions Continued 

Subfamily Cyprideinae Continued 

Genus Cypridea Continued

Subgenus Bisulcocypridea-. 

Genus Paracypridea_ _ _ ________

Family unknown.________________

Genus Petrobrasia_____________

References cited______________________

Page

B6

7

7

7

7

ILLUSTRATIONS

[Plates follow references]

PLATE 1. Cypridea (Cypridea).

2. Cypridea (Bisulcocypridea), Petrobrasia?, and "Paracypridea."

FIGURE 1. Index map of Nevada showing approximate location of areas of Cretaceous nonmarine 

sedimentary rocks-___-_____________________________-_------_---------__----

Page

Bl

nx

CONTRIBUTIONS TO PALEONTOLOGY

NONMARINE OSTRACODES OF EARLY CRETACEOUS AGE FROM PINE VALLEY

QUADRANGLE, NEVADA

By I. G. SOHN

ABSTRACT

Nonmarine Cypridea (Cypridea) pecTfl n. sp. and C. (Bisulco^- 

cypridea) vicostata n. subgen., n. sp. are described from Nevada. 

C. (G.) pecki, associated in Nevada with "Paracypridea" sp. and 

PetrolM-asia 1} sp., was recorded from the Draney Limestone 

(upper Aptian) of Idaho-Wyoming as C. diminuta Vanderpool, 

1928. Its presence indicates that the age of the rocks in Nevada 

is late Aptian. C, (C.) luMmovae new name is proposed for 

C. spinigera Lubimova, 1956, not C. spinigera (Sowerby), 1836.

INTRODUCTION

A nonmarine ostracode faunule of Early Cretaceous 

age was discovered during geologic mapping in Elko 

County, Nev. In 1956, J. F. Smith and K. B. Ketner 

collected a sample of dark mudstone, which contains 

carbonaceous inclusions and many poorly preserved 

ostracodes, from an unnamed formation in the Pine 

Valley quadrangle (fig. 1, loc, 2). I was guided to this 

locality in July 1959 by J. F. Smith, K. B. Ketner, Jack 

Wolfe, and Pedro Gelabert, all of the U.S. Geological 

Survey, and made two collections: one (USGS Mesozoic 

loc. 27753), from about halfway up the shale slope in 

the center of W%NW% sec. 21, T. 29 N., R. 53 E.; the 

second (USGS Mesozoic loc. 27754), from the original 

locality at the top of the slope.

ACKNOWLEDGMENTS

I am grateful to J. F. Smith and K. B. Ketner for 

guiding me to the localities. Photographs are by D. H. 

Massie and R. H. McKinney, and the plates were assembled by Elinor Stromberg and Sharie L. May, all 

of the Geological Survey. Prof. Nicolas Grekoff, of the 

Institut Francois du Petrole, Paris, furnished duplicates of his species and permitted me to illustrate one 

of the specimens.

CRETACEOUS SEDIMENTARY ROCKS IN NEVADA

Only four Cretaceous formations that have typelocalities in Nevada have been known previously. This 

report documents an additional Nevada occurrence of

Lower Cretaceous fossiliferous rocks. Smith and Ketner 

(oral commun., Nov. 1967) tentatively correlated 

the ostracode-bearing sedimentary rocks in Elko County 

with the Newark Canyon Formation in the Eureka 

district.

Pine Valley quadrangle

-j Franklin Lak" '

2 I?

Ruby Lake

FIGURE 1. Index map of Nevada showing the approximate 

location of areas from which Cretaceous nonmarine sedimentary rocks have been reported. Locality numbers are referred 

to in the text.

BJ
B2 CONTRIBUTIONS TO PALEONTOLOGY

Longwell (1949, p. 931-933) described the Upper Cretaceous Baseline Sandstone and the Willow Tank Formation from the Muddy Mountain area near Las Vegas, 

in southern Nevada (fig. 1, loc. 4), and the Upper 

Cretaceous (?) Thumb Formation (Longwell, 1952, p. 

35) from Frenchman Mountain, also in southern Nevada 

(fig. 1, loc. 5). Ostracodes found in the Willow Tank 

Formation were examined by Peck, who referred to 

them (in Longwell, 1949, p. 932) as "* * * numerous 

specimens of a species of Metacypi*is that are also found 

in the Gannett group and Bear River."

Nolan and others (1956, p. 69) described the Lower 

Cretaceous Newark Canyon Formation from the Eureka 

district (fig. 1, loc. 3). The age was based on previously 

described mollusks (MacNeil, 1939) and a species of 

fish (David, 1941). A slab from this formation that 

bears a specimen of the fish Leptolepis nevadensis 

David, 1941, contains molds and casts of ostracodes that 

are smooth and that differ on the family level from those 

described in this paper. Willden (1958, p. 2382-2391) 

described the King Lear Formation from the Jackson 

Mountains, Humboldt County (fig. 1, loc. 1). An Early 

Cretaceous age for this formation is based on the identification by J. B. Reeside, Jr., of a collection of mollusks 

which he considered to be similar to those described by 

MacNeil (1939).

INTERPRETATION OF THE OSTRACODES

One collection (USGS Mesozoic loc. 27753) contains 

abundant ostracodes, among which are a notched type 

belonging to Cypridea (Cypridea) pecki n. sp. Representatives of this species were previously identified by 

Peck (1941, p. 298) from the Draney Limestone (upper 

Aptian) of Idaho-Wyoming as being the lower Albian 

C. dimmuta Vanderpool, 1928. C. (C.) pecki suggests 

a late early Cretaceous age for the sedimentary rocks in 

Nevada.

The other collection (USGS Mesozoic loc. 27754) does 

not contain C. (C.) pecki; it contains abundant poorly 

preserved specimens of a notched bisculcate ostracode 

C. (BiscuLcocypridea) bicostata n. sp., to the virtual 

exclusion of other forms. A few smooth very poorly 

preserved ostracodes are present, but they are unidentifiable. Because C. (B.) bicostata is new and not closely 

related to known species, it does not aid in determining 

the geologic age of the rocks.

The fresh-water Early Cretaceous Cyprideinae have 

a worldwide distribution. Unlike other fresh-water 

ostracodes, this group developed considerable variability 

in the shell morphology; consequently, individual 

species are easily recognized, and misidentification is 

less likely than in the smooth, nondescript forms.

C. (C.) pecki n. sp. and C. (C.) diminuta Vanderpool, 1928, in North America differ only lightly in 

size, shape, and surface ornament from the older 

(Wealden) C. (C.} ultima Grekoff, 1957, ard C. (C.) 

pnmar'm Grekoff and Krommelbein, 1967, in Africa and 

from the Barremian C. (Ulwellia) karataigysensis 

Lubimova, 1956, in the Ciscaspian of Eurasia. C. 

liystricoides Krommelbein, 1962 (Late Jurassic? to 

Early Cretaceous), from Brazil is represented by a close 

relative, C. n. sp. aff. C. hystricoides Krommelbein, in 

probably somewhat younger beds in Israel (£ihn, 1968, 

pi. 1, figs. 22, 23). It is particularly significant that the 

same species have been identified in beds of approximate 

similar ages on both sides of the South Atlant: ?-. Grekoff 

and Krommelbein (1967) identified and illustrated 

seven species of Cypridea and three additional related 

species from the Cocobeach Series of Gabon, Africa, 

that were originally described from the Bahia Series 

of Brazil. The total number of Brazilian fo^ms found 

in Africa is 30 species and six related species, all 

distributed in 10 genera.

The circumglobal distribution of Cypridea suggests 

that the group possibly deposited eggs that ciuld withstand dessication. This hypothesis is supported by the 

morphology of the carapace. Dimorphism in Cypridea 

is unknown, although Krommelbein (1961) described 

sexual dimorphism in Paracypridea as consisting of a 

somewhat wider posterior in dorsal outline of heteromorphs. This difference in width is not as pronounced' 

as it is in the Metacypris-Gomphocythere-Theriosynoecum group, in which the females have an inflated 

posterior. I have found first and second instars associated with eggs within the inflated posterior of an as 

yet unidentified species of a living "Metacypris" and 

Elofson (1941, p. 368) noted that certain genera having 

inflated posteriors are viviparous. The absence of an inflated posterior in Cypridea and related genera suggests 

that the group was not viviparous and that the females 

deposited their eggs. There is no evidence for or against 

parthenogenesis in the Cyprideinae, except that Paracypridea may have been dioecious. Many mocSrn freshwater ostracodes deposit eggs that can withstand dessication, and this property is considered to facilitate their 

wide distribution.

The large distances between localities from which 

Cyprideinae have been described in North America, 

South America, Eurasia, Asia Minor, and North Africa 

requires an explanation. The hypothesis of continental 

drift (Krommelbein, 1966a, 1966b) does not explain 

this wide distribution, because even if the continents 

were closer to each other during Early Cretaceous time, 

the distances between localities would still have been 

considerable. These nonmarine organisms require a
CRETACEOUS OSTRACODES, PINE VALLEY QUADRANGLE, NEVADA B3

transporting agent for their dispersal. Although small 

aquatic organisms may be transported and dispersed by 

many animals, their main means of dispersal is considered to be winds, insects, and birds. The fact that one 

Cyprideinae locality is south of the present equator and 

the rest are north of the equator, and that Cyprideinae 

distribution is circumglobal from north to south, would 

rule out winds and insects that are dependent on winds 

for their distribution as effective agents of Cyprideinae 

dispersal.

Proctor (1964) proved that ostracodes can be distributed by birds. He cultured fresh-water ostracodes 

from eggs obtained from fecal pellets and from the 

lower digestive tracts of domestic and wild ducks.

All these considerations suggest that the Early Cretaceous freshwater ostracodes may have been dispersed 

by migratory birds, but the obvious difficulty with this 

hypothesis is that migratory birds of Early Cretaceous 

age are not known. The oldest recorded birds in North 

America are Ichthyornis and Hesperornis from the 

Niobrara Formation (Late Cretaceous) of Kansas 

(Romer, 1950, p. 263; 1966, p. 167). Ichthyornis was 

similar to a modern tern in structure; it may have been 

able to travel considerable distances (Thomson, 1964, 

p. 323). In addition, Fisher (1967, p. 735) recorded the 

stratigraphic range of the Phoenicopteriformes as 

Barremian, and probably Berriasian, to Holocene and 

indicated that the Enaliornithidae of Albian age were 

possibly ancestral to the Gaviifornies of Maestrichtian 

to Holocene ages. Both the Phoenicopteriformes and the 

Gaviifornies are strong fliers. The possibility that additional, as yet undiscovered, birds existed during Early 

Cretaceous time should not be discounted.

SYSTEMATIC DESCRIPTIONS 

Subfamily CYPRIDEINAE Martin, 1940

Diagnosis. Straight-hinged smooth or ornamented 

inequivalved ostracodes having a well-developed to a 

weakly developed anteroventral beak and closed notch 

(furrow) extending upward from ventral margin; 

ridge and groove hingement; terminal dentition weak 

or lacking.

Discussion. When I previously discussed this group 

(Sohn, 1958, p. 122), I recorded the stratigraphic range 

as Middle Jurassic through Eocene and listed the following genera in the Cyprideinae:

Cyamocypris Anderson, 1939

Cypridea Bosquet, 1852

Langtonia, Anderson, ~L939=Pseudocypridma Koth, 

1933

Morinia Anderson, 1939 [misspelling of Morinina]

Paracypridea Swain, 1946

Pseudocypridina Roth, 1933

UlweUia Anderson, 1939 Cypridea Bosquet, 1852 

All these genera were treated as synonyms of Cypridea in the Russian treatise (Lubimova, Maiidelrtam, 

and Schneider in Tchernyslieva, 1960, p. 353), and their 

stratigraphic range was recorded as "Upper PermianOligocene." I am grateful to Dr. G. F. Schneider, Vsesoyuznyi Neftyanyi Nauchno-Issledovatelskii GeologoRazvedoclinyi Institut (VNTGRI), Leningrad (written commun., 1967), for the information that Mandelstam (1956, p. 103) had discovered a species of Cypridea 

in the lower horizons of the Il'inskoi Formation (Permian) in the Kuznetzk Basin. Until that species is described and illustrated, a Late Permian range for Cypridea remains in doubt. The Oligocene occurrence is based 

on the description and illustrations of the Early 

Cretaceous species C. spinigera (Sowerby), 1836, from 

the Hamstead Beds (Middle Oligocene) on the Isle of 

Wight by Jones and Sherborn (1889, p. 14, pi. 1, figs. 

8-11; pi. 3, figs, la, b). I discussed this anomalous occurrence with Dr. F. W. Anderson at the Institute of 

Geological Sciences, London, in July 1967. Dr. Anderson stated that he had investigated this problerr and 

concluded that the alleged Oligocene specimens are 

similar in preservation and color of the matrix to V^eald 

Clay and not to the Hamstead sedimentary rocks. Furthermore, notched ostracodes have not been found again 

in rocks of Oligocene age; consequently, it is reasonable 

to assume that there had been a mixup in labels anc1 that 

the C. spinigera specimens are of Early Cretaceous age. 

Sylvester-Bradley (1949, p. 127) and Anderson (1967, 

p. 249) hinted at the same conclusion.

The American treaties (Swain, in Moore, 1961, p. 

Q241) considered the genera in my original list as being 

subgenera of Cypridea and added to the subf arnih7 the 

subgenus C. (Hwnenia) Hou, 1958, and the Triassic 

genus Cultella Lubimova, 1959.

Krommelbein (1962, p. 460, 471) described two subgenera from the Bahia Series in Brazil (Upper Jurassic 

to Lower Cretaceous) : C. (Sebastianites] and C. (Morininoides). C. (Morininoides) has an anteroventral 

beak and notch, but C. (Sebastianites) was defined as 

being with or without an anteroventral beak. The typespecies C. (8.) fida Krommelbein, 1962, and one additional species, C. ($.) devexa Krommelbein, 1962, do 

not have anteroventral beaks; therefore, because this 

structure is diagnostic of the Cyprideinae, the subgenus 

Sebastianites is not considered to belong to Cyp^ea. 

Instead, C. (8.) fida seems to be related to the Early 

Cretaceous genus Dsunbaina Galeeva, 1955, orig; nally 

assigned to the Limnocypridae. Krommelbein (1962, p. 

463-466) described and illustrated three additional 

species, one having two subspecies, as Sebastiardtesl.
B4 CONTRIBUTIONS TO PALEONTOLOGY

These taxa do have the diagnostic anteroventral structures and should be reassigned in the Cyprideinae.

Mandelstam (in Mandelstam and Schneider, 1963, 

p. Ill, 113) referred to the Cyprideinae the new genera 

Latonia Mandelstam, 1963, and Zejaina Mandelstam, 

1963, both from Lower Cretaceous sedimentary rocks. 

These two genera, Cultella Lubimova, 1959, and CyprideanwrpJieUa Mandelstam, 1956, do not have anteroventral beaks and notches; consequently they do not belong in the Cyprideinae as denned above and also as 

denned by van Morkhoven (1963, p. 6), who stated 

"* * * typically with a more or less prominent anteroventral beak * * *.v

Cypridea and related genera are unknown from normal marine environments. More than 275 species have 

been described in the genus Cypridea, and more than 

half of these are from Lower Cretaceous deposits.

Triebel (1960) showed similarities in shell morphology between Cypridea and the living genus Clilamydotheca Saussure, 1858 (subfamily Cypridinae Baird, 

1845). Except for the alleged Late Permian record of 

notched forms, ancestral forms of Paleozoic or early 

Mesozoic age are unknown.

The beak of the continental Pliocene genus KarsMcypridea Gramm and Bukharina, 1967, is more similar 

to that of Acratia Delo, 1930, and related genera of Devonian to Triassic age than to the Cyprideinae. In addition, the adductor muscle-scar pattern of Karshicypride a resembles more that of Candana Baird, 1845, than 

that of Cypridea. The probable function of the beak 

(rostrum) is unknown, although Gramm and Bukharina (1967, p. 97) "guessed" that a second pair of 

antennae may have been involved. The absence of any 

muscle-scars that would indicate such organs invalidates that hypothesis.

Genus CYPRIDEA Bosquet, 1852

1852. Cypridea Bosquet, (1850-51), Aead. Royale Sci. Bedgique

Mem., v. 24, p. 47. 

1949. Cypridea Sylvester-Bradley, Geologists' Assoc., London

Proc., v. 60, pt. 2, p. 130. 

1959. Cypridea Wolburg, Senckenbergiana Lethaea, v. 40, p. 242

(see for synonymy). 

1967. Cypridea Anderson, in Anderson, Bazley, and ShepihardThorn, Great Britain Geol. Survey Bull. 27, p. 201.

Type-species (subsequent designation by SylvesterBradley, 1947) Cypris gramdosa Sowerby in Fitton 

(1836, p. 345, pi. 21, fig. 4). Middle Purbeck (Jurassic), 

England.

Diagnosis. Cyprideinae less than 2 mm (millimeters) in greatest length, smooth, punctate, reticulate, 

tuberculate or spinose, having incised dorsum.

Discussion. As indicated in the discussion of the subfamily, there have been differences of opinion as to the 

classification of these notched ostracodes. Some consider 

segments as genera, others consider them as subgenera, 

and a few would lump most into the one genus Cypridea.

Wolburg (1959) divided the notched forms in the 

Weal den of northwest Germany into two superspecific 

groups one with normal overlap (Cypridea A), the 

other with reversed overlap (Cypridea J$ = Ulwettia 

Anderson, 1939). Reversal of overlap and hingement is 

not a good criterion for discriminating genera and 

species because some taxa consistently erhibit this 

feature; for example, the dextral-sinistral ratio may 

vary from 1:1, as in SansabeUa amplectens Roundy, 

1926, to 1:250 or more, as in Aurikirldbya wordensis 

(Hamilton), 1942. However, when reversal of overlap 

and hingement is consistent within a group of species, I 

consider it convenient to use that as a criterion for subgeneric differentiation, and therefore I retain Ulwellia 

Anderson, 1939, as a subgenus in Cypridea.

Other species-groups that were designated by Wolburg (1959, p. 240) constitute distinct forms that should 

be designated as subgenera. For example, the C. altogroup (Wolburg, 1959, p. 262) should be assigned to C. 

(Pseudocypridina) Roth, 1933. Swain (in Moore, 1961, 

p. Q242) did not correctly interpret this tayon because 

his specimens from Brazil, which he identified as C. 

(Pseudocypridina} piedmonti Roth, 1933 (Swain, 1946, 

p. 550, pi. 83, figs. 10-12), are neither conroecific nor 

congeneric with Roth's types from the Black Hills of 

South Dakota. Swain's specimens have since been described and illustrated by Krommelbein (1962, p. 457, 

pi. 59, figs. 39a, b) as C. salvadorensis salvadorensis 

Krommelbein, 1962.

The published record of Cypridea and related genera 

contains a group having only one sulcus; C. (Morinina) 

Anderson, 1939, was defined as having a subcentral 

sulcus. C. (Morininoides) Krommelbein, 1962, differs 

from C. (Morinina) in having three nodea Bisulcate 

species in Cypridea are here referred to the new 

subgenus C. (Bisulcocypridea,}.

Key to the subgenera

1. Nonsulcate____--_-_-_-_-_-----__------------ 2

la. Sulcate-__--__------------------------------ 4

2(1). Left valve larger____--__----_----_----------- 3

2a. Right valve larger___-_---_---------__---_- Ulwellia

3 (2). Ventrolateral ridge on left valve_ _____ Pseudocypridina

3a. No ventrolateral ridge on left valve ______ Cypridea

4 (la). One sulcus__________________ Morinina, Morininoides

4a. Two sulci______________----------- Bisulcocypridea

Stratigraphic range. Middle Jurassic to Focene.
CRETACEOUS OSTRACODES, PINE VALLEY QUADRANGLE, NEVADA B5

Subgenus CYPRIDEA Bosquet, 1852

Type-species. Same as for the genus.

Diagnosis. Nonsulcate; left valve larger; smooth, 

punctate, reticulate, tuberculate or spinose; without 

ventrolateral ridge on left valve.

Discussion. The record contains 190 species and subspecies which conform with the above description. Three 

homonyms were noted: one has an available synonym 

discussed below, a substitute name is proposed for the 

second and the state of homonymy of the third is 

recorded.

Stratigraphic range. Middle Jurassic to Upper Cretaceous. The majority of the described species are from 

the Lower Cretaceous.

Cypridea (Cypridea) kleinbergi Galeeva, 1955

Cypridea Kleiribergi Galeeva, 1955, Moscow, VNIGNI, p. 31, pi.

8, figs. 2a-e [d]. Lower Cretaceous, Mongolia. 

Cypridea, bispinosa Galeeva, 1955, Moscow, VNIGNI, p. 36, pi. 9,

figs, la-d [g]. Same locality as above. 

Lubimova, 1956, VNIGRI, Trudy, n. ser., no. 93, p. 25, pi.

5, figs. 2 4. Same locality as at>ove. 

[not] Cypridea bispin&sa Jones, 1878, Geol. Mag. new ser., Dec.

2, v. 5, p. 109, pi. 3, figs. 9,10. Lower Cretaceous, England, 

[not] Cypridea ventrosa var. bispinosus Vanderpool, 1928, Jour.

Paleontology, v. 2, p. 104, pi. 14, figs. 1, 2=Cypridea dequeenensis Swain and Brown, 1964.

According to Lubimova (1956, p. 25), C. Membergi 

was based on young individuals of C. bispinosa. Because 

C. bispinosa is a junior synonym, C. kleinbergi is 

available for that species.

Cypridea (Cypridea) lubimovae Sohn, new name

Cypridea spinigera Lubimova, 1956, VNIGRI, Trudy, n. ser., 

No. 93, p. 55, pi. 12, figs, la-c [v]. Lower Cretaceous, 

Mongolia.

[not] Cypris spinigera Sowerby in Fitton, 1836, Geol. Soc. London Trans., ser. 2, v. 4, p. 345, pi. 21, fig. 3. Wealden, 

England.

Ho we and Laurencich (1958, p. 135) and Gory ell 

(1963, p. 564) noted the state of homonymy without 

proposing a substitute name. Because of the tune interval between the above two publications and the present, 

during which a substitute name has not been published 

by Lubimova, C. (Cypridea) lubimovae is here 

proposed.

Homonym not renamed

The following junior homonym is not renamed because its author was not informed of the homonymy. 

Cypridea rostrata Galeeva, 1955 (p. 42, pi. 9, figs. 3a-c), 

from Upper Cretaceous deposits of Mongolia, is preoccupied by Cypris rostrata Dunker, 1843 (p. 173), 

which was later illustrated by Dunker (1846, p. 61, pi. 

13, fig. 27). Dunker's illustration is definitely of a

359-232 O 69 2

Gypridea, and Martin (1940, p. 284) transferred that 

species to this genus.

Cypridea (Cypridea) pecki Sohn, n. sp. 

Plate 1, figures 1-4, 7-9,12-16

Cypridea dimmwta Vanderpool. Peck [part], 1941, Jour. Paleontology, v. 15, p. 298, pi. 44, figs. 29-31 [not fig. 32=C. 

(Cypridea) dinunitta Vanderpool, 1928]. Draney Limestone, Wyoming-Idaho.

Peck, 1951, Jour. Paleontology, v. 25, p. 312, pi. 49, fig. 6. 

Same formation and locality as above.

Howe and Laurencich, 1958, Louisiana State Univ. Press, 

p. 121, figure on p. 122. Same formation and local'ty as 

above.

Name. In honor of Dr. E. E. Peck, University of 

Missouri.

Holotype. USNM 162797.

Paratypes. USNM 162798-162802.

Material. Several hundred valves, a few carapaces.

Type-locality M&GtS Mesozoic locality 27753.

Type-level. Upper Aptian (Lower Cretaceous).

Diagnosis. Small, less than 0.9 mm in greatest 

length, subquadrate, reticulated; without pustules, 

spines, or nodes; rostrum blunt, weakly developed, without furrow.

Description. The valves aresubovoid in lateral view; 

the ventral margin is straight; the dorsal mr.rgin 

straight to very gently curved; the anterior margin is 

slightly more convex than the posterior margin and 

meets the dorsal margin at about one-fourth the greatest 

length; the posterior margin joins the ventral mp.rgin 

approximately at 90° in the right valve and slightly 

more than 90° in the left valve. The overlap is slight 

along free margins; the hinge of the left valve is a 

groove into which the dorsal edge of the right valv, fits. 

The surface is covered by distinct, minute, polygonal 

reticulations which do not extend to the periphery of 

the valve. The sides are straight and subparalM in 

dorsal outline.

Measurements (in mm). 

Specimen

Fig. No. Maximum Maximum Maximum 

(pi. 1) length height width

Holotype. 

Paratype.

Do...

Do...

Do...

Do...

Do...

1-4 

7

8,9 

12

13,15 

14 

16

0.78 

.64 

.66 

.66 

.60 

.60

0.45 

.37 

.34 

.38 

.33 

.34 

.42

0.33

Discussion. This species is similar to C. diminuta 

Vanderpool, 1928, from which it differs in having a 

more subdued dorsoanterior angulation and in lacking 

scattered small pustules. Peck's specimens from the 

Draney Limestone (Lower Cretaceous), Idaho-T^yo-
B6 CONTRIBUTIONS TO PALEONTOLOGY

ming, identified as C. diminuta Vanderpool, 1928, are 

conspecific with the specimens from Nevada.

In size, shape, and surface ornament the new species 

resembles C. (C.) d^ramwto Vanderpool, 1928 (pi. 1, figs. 

5, 6), C. (C.) ultima Grekoff, 1957 (pi. 1, fig. 10, 11), 

from the Wealden of the Congo Basin, and C. 

(Uhcellia.) karataigysensis Lubimova, 1956, from the 

Barremian of the Ciscaspian Depression. The geographic distribution of these species is discussed earlier 

in this report. I do not know the affinities of the 

Wealden specimen from the Congo Basin, Africa, that 

was illustrated by Grekoff (1957, p. 55, pi. 2, fig. 36) 

as (?) Cypridea dhninuta Vanderpool, 1928.

Submenus BISTTLCOCYPRIDEA Sohn, n. subgen.

Type-species. Cypridea (Bisul<cocypridea) bicostata 

Sohn, n. sp.

Diagnosis. Bisulcate, smooth or punctate; may bear 

pustules, nodes, or spines.

Discussion. Swain (1949, p. 180) suggested that the 

bisulcate f onus might belong to a distinct subgenus, but 

because at that time its separation would serve no stratigraphic purpose, he did not describe the new taxon. In 

addition to C. (B.) bwostata, the following species 

should be referred to this subgenus:

Ilyocypris arvadensis Swain, 1949, Jour. Paleontology, v. 23,

p. 178, pi. 32, figs. 20-22; pi. 33, figs. 1-9. Paleocene and

Eocene, Western United States, 

[not] Ilyocypris arvadetisis tuberculata Swain, 1949, Jour.

Paleontology, v. 23, p. 179, pi. 33, figs. 10-12=71{j/ocypromorpha linonodosa (Swain), 1951. 

Cypridea Msulcata Swain, 1949, Jour. Paleontology, v. 23, p. 180,

pi. 33, figs. 13-19, Wasatch Formation (Eocene), Utah. 

Psetidocypridma laevioula. Peck, 1951, Jour. Paleontology, v. 25,

p. 319, pi. 48, figs. 1-4. Bear River Formation (Albian,

Lower Cretaceous), Wyoming. 

^Cypridea mera Stepanaitis, 1967, Paleont. Zhur., 1967, no. 2,

p. 76, text figs. c. Barremian, western Turkmenia. 

Cypridea nyensis Swain, 1964, Jour. Paleontology, v. 38, p. 278,

pi. 44, figs. 9a-c. Early Tertiary ?, Nevada. 

Cypridea orientalis orientalis Bischoff, 1963, Senckenbergiana

Lethaea, v. 44. p. 304, pi. 42, figa 1-4. Lower Aptian,

Lebanon.

Cypridea orientalis tenuituberosa Bischoff, 1963, Senckenbergiana Lethaea, v. 44, p. 305, pi. 42, figs. 5, 6. Lower Aptian,

Lebanon. 

Cypridea skeeterl Peck, 1951, Jour. Paleontology, v. 25, p. 316,

pi. 49, figs. 15-26. Bear River Formation (Albian, Lower

Cretaceous), Wyoming. 

"> Cypridea (Cypridea) Y 187 Grekoff, 1960, Mus. Royal Congo

Beige Annales, Sci. Geol., v. 35, p. 41, pi. 6, figs. 39, 40.

Wealden B, Congo Basin, Africa.

Stratigraphic range. Lower Cretaceous to Eocene.

Cypridea (Bisulcocypridea) Mco&tata Sohn, n. sp.

Plate 2, figures 1-10, 13-15

Name. Two horizontal ridges on each valve. 

Holotype. USNM 162808.

Paratypes. USNM. 162804-07, 162809, 162810, 

162815, 162816.

Material. More than 100 poorly preserved crushed 

valves; a few carapaces.

Type-locality. USGS Mesozoic locality 27754.

Type-level. Upper Aptian (Lower Cretaceous).

Diagnosis. Has lateral ridges near dorsal and ventral margins; dorsal ridge interrupted by sulci; surface 

smooth or finely pitted, scattered spinelets sparse on 

lateral surface, more abundant near end margins; beak 

blunt, furrow extends to approximately lower third of 

greatest, height; dorsal and ventral margins straight, 

converge gently toward posterior.

Description. The lateral outline is subqur.drate and 

has gently rounded end margins; the dorsal and ventral 

margins converge slightly toward the poster5 or so that 

the posterior margin is not so high as the anterior margin. The anterior cardinal angle is distinct, approximately in line with post rostral furrow. The ventral 

ridge is thin, subparallel to the ventral margin, and 

extends from the furrow to the posterior margin. This 

ridge overhangs the contact margin in some ir dividuals, 

and in others it is slightly above the ventral margin. 

The dorsal ridge is thick and high; it is well developed 

along the posterior of the valve near the dorsal margin, 

where it extends above the hingeline; it is terminated 

by the sulci, where it appears to bifurcate toward the 

anterior. The lower branch of the dorsal ridge extends 

over the top of the central lobe and continues as the 

lower part of a pinched anterior lobe; the upper branch 

extends above the central lobe and continues as the 

upper part of the anterior lobe. Both sulci are deep, start 

below the dorsal margin, and extend downward to above 

midheight. The beak is blunt and extends slightly below the ventral margin; it is bordered by a distinct, 

anteriorly convex furrow that extends upward and 

terminates below midheight. Minute pustule-s are scattered on the surface of the valves; they appear to be 

more abundant over the anterior part of the valve in 

front of the furrow and also on the posterior quarter of 

the valve. The dorsal margin extends to tH anterior 

cardinal angle as a thin crest. The venter is flat; the 

overlap along the ventral margin is slight.

Measurements (in mm). 

Specimen

Figure 

number 

(pl. 2)

Maximum

length

(parallel

to dorsal

margin)

Maximum

height

(normal

to dorsal

margin)

Maximum 

width

Holotype. 

Juvenile. . 

Paratype.

Do-..

Do...

Do___

Do...

Do...

Do._-

13 

1

2,3 

4

5-8 

10 

9

14

15

1.25

.78

.99

1.15

.99

1.06

1.06

1.22

0.?2 

.51 

.69 

.f9

.e«

.70 .ffi

.64 

.60

0.40
CRETACEOUS OSTRACODES, PINE VALLEY QUADRANGLE, NEVADA B7

Discussion. In addition to rare juveniles (pi. 2, fig. 

1), the species is represented by forms that differ in 

lateral outline. The largest specimen (pi. 2, fig. 13) is 

much higher in the posterior than slightly shorter specimens (pi. 2, fig. 14), but both types have proportionally the same width in dorsal outline. Whether this 

difference in height of the posterior represents dimorphism cannot be demonstrated with the material on hand. 

All measurements of the height are from the straight 

dorsal margin, below the overreaching ridge crest, to 

the base of the notch. The one measurement of width 

was from the venter and does not include the overreaching ridges along the dorsal margin.

Genus PARACYPRIDEA Swain, 1946

"Paracypridea" sp. 

Plate 2, figures 17-20

More than 50 valves filled with matrix including 

fragments and partly exfoliated valves of large, 

rather thin-shelled, elongated, notched ostracodes are 

associated with Cypridea (Cypridea) pecM at USGS 

Mesozoic locality 27753. A partly exfoliated right valve 

that has a preserved muscle-scar pattern was lost during 

scanning electron micrography. The muscle-scar pattern seen on the illustrated specimen (pi. 2, figs. 19, 20) 

was observed as colored spots on several additional 

specimens when they were wetted. This pattern differs 

from that of Paracypridea Swain, 1946, in having fewer 

and proportionally larger individual scars. The general 

configuration is similar to that of the candonid type. 

Because the general size and outline is similar to Paracypridea, I am referring the specimens from Nevada 

in open nomenclature to Paracypridea.

Measurements (in mm). 

Maximum Maximum 

length height

Figured specimen (pi. 2, fig. 18). 2.12 1.21

Age. Late Aptian (Early Cretaceous). 

Locality. USGS Mesozoic locality 27753.

Family unknown 

Genus PETROBRASIA Krommelbein, 1965

Petrobrasia Krommelbein, 1965, Senckenbergiana Lethaea, v. 

46a, p. 193. Grekoff and Krtfmrnelbein, 1967, Inst. Frangais 

P£trole Rev., v. 22, no. 9, p. 1327.

Type-species (original designation). Dolerocypris? 

marfinensis Krommelbein, 1962 (p. 489, pi. 58, figs. 38a, 

b). Sao Sebastiao Beds (Lower Cretaceous), well in 

Beconcavo, Bahia, Brazil.

Discussion. Krommelbein established Petrobrasia 

for some Mesozoic cyprid ostracodes that had been referred to Holocene genera, in part because the internal shell structure of the Mesozoic forms is unkrown. 

The genus was diagnosed as having strong to weak 

surface ribbing or being smooth shelled. CetaceUa 

Martin, 1958, differs in having a more rugose surface 

sculpture and a distinctive muscle-scar pattern, a, feature as yet not described in Petrobrasia. Fragments 

from Nevada (pi. 2, figs. 11, 12) have a muscle-scar 

pattern which differs from that of CetaceUa; consequently the valves and associated fragments are tentatively referred to Petrobrasia.

Petrobrasia? sp. 

Plate 2, figures 11, 12, 16

More than 50 fragments and valves filled with matrix 

are associated with Cypridea (Cypridea) pecki at 

USGS Mesozoic locality 27753. The surface of these 

specimens is smooth, and the lateral outline is similar to 

two smooth forms previously placed in Petrobrasia: 

P. gibbosa Krommelbein, 1965, from the Upper Ulhas 

Formation of Brazil; and P. gl-abra Grekoff and Krommelbein, 1967, from Gabon, Africa. Because wellpreserved specimens are not available, this species has 

not been formally named. Plate 2, figures 11 and 12, 

show the muscle-scar patterns of fragments of a right 

and a left valve. One left and two right broken valves 

were converted to fluorite, and all have the same two 

small scars shown on the lower right of the muscle-scar 

pattern, which indicates that the scars are not artifacts. 

Two small antennal scars are present to the left and 

above the central muscle-scar group.

Measurements (in mm}. 

Maximum Maximum 

length he'ght

Figured specimen (pi. 2, fig. 16). 1.31+ 0.87+

Age. Late Aptian (Early Cretaceous). 

Locality. USGS Mesozoic locality 27753.

REFERENCES CITED

Anderson, F. W., 1939, Wealden and Purbeck Ostracoda: Annals and Mag. Nat. History, ser. 11, v. 3, p. 291-310, pis. 

12, 13.

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Anderson, F. W., Bazley, R. A. B., and Shephard-Thorn, F. R., 

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Great Britain Geol. Survey Bull. 27, p. 171-235, pis. 9-15, 3 

text figs.

Bischoff, Gunther, 1963, Die Gattung Cypridea im Aptier inferieur: Senckenbergiana Lethaea, v. 44, no. 4 p. 301-319, 

pis. 42-44.
B8 CONTRIBUTIONS TO PALEONTOLOGY

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ostrakody v neogene Uabekistana: Paleont. Zhur., 1967, 

no. 4, p. 95-101, pi. 6, 6 text figs.

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bassin: Mus. Royal Congo Beige Annales, Sci. Geol., v. 19, 

97 p., 6 pis.

 1960, Ostracodes du bassin du Congo [Pt.] II Cretac6: 

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10 pis.

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atlantiques; Serie de Cocobeach, Gabon et Serie de Bahia, 

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9 pis., 14 text figs.

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study of Cretaceous Ostracoda: Baton Rouge, Louisiana 

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Palaeontographical Soc., 55 p., 3 pis.

Krommelbein, Karl, 1961, Uber Dimorphismus bei Arten der 

Ostracoden-Gattung Paracypridca Swain (Cyprideinae) 

aus dem NE-brasilianischen "Wealden:" Senckenbergiana 

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 1962, Zur Taxionomie und Biochronologie stratigraphisch 

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 1965, Neue, fur Vergleiche mit West-Africa wichtige 

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 1966a, On "Gondwana Wealden" Ostracoda from NE 

Brazil and West Africa [with discussion] : West African 

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118, 1 chart.

 1966b, Paleontological evidence for continental drift

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968,11 pis., 14 text figs.

 1952, Basin and Range geology west of the St. George 

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2

fi<rc llg».

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CRETACEOUS OSTRACODES, PINE VALLEY QUADRANGLE, NEVADA B9

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PLATES 1, 2
PLATE 1

[Magnification as indicated. Photographs by B. H. McKinney. Scanning electron micrographs by D. H. Massie]

FIGURES 1-4, 7-9, 12-16. Cypridea (Cypridea) pecki Sohn n. sp. (p. B5).

1-4. Right, ventral, left, and dorsal views of carapace; 

approximately X 30. Holotype, USNM 162797.

7. Outside view of left valve; approximately X 60. Paratype, 

USNM 162798.

8. 9. Outside and ventral views of right valve; approximately 

X 60. Paratype, USNM 162798A.

12. Inside view of left valve; scanning electron micrograph; 

X 135. Paratype, USNM 162799.

13. 14. Inside views of two right valves; scanning electron 

micrographs; approximately X 150. Paratypes, USNM 

162800, 162801.

15. Muscle-scar pattern of specimen illustrated as figure 13; 

X 720.

16. Left view of carapace, scanning electron micrograph;

X 125. Paratype, USNM 162802. 

5, 6. Cypridea (<7.) diminuta Vanderpool, 1928 (p. B6).

Dorsal and right views of holotype; X 30. USNM 132523.

DeQueen Limestone (lower Albian), Ark. 

10, 11. Cypridea (C.) ultima Grekoff, 1957 (p. B6).

Left and ventral views of carapace; X 30. Topotype USNM 

162803. Wealden, Congo Basin, Democratic Republic of 

the Congo, Africa.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 643-B PLATE 1

16

CYPRIDEA (CYPRIDEA)
PLATE 2

[Except where otherwise indicated, magnification approximately X 30 and except where otherwise indicated, photographs

by R. H. McKinney]

FIGURES 1-10, 13-15. Cypridea (Bisulcocypridea) bicostata Sohn, n. sp. (p. B6).

1. Outside view of left valve, juvenile. Paratype, USNM 162804.

2. 3. Outside and inside views of left valve, preadult stage.

Paratype, USNM 162805.

4. Outside view of right valve. Paratype, USNM 162815. 

5-8. Right, dorsal, left, and ventral views of carapace. Paratype,

USNM 162806.

9. Outside view of left valve. Paratype, USNM 162807.

10. Inside of right valve converted to fluorite. Paratype, USNM 

162816.

13. Outside view of adult left valve. Holotype, USNM 162808.

14. Outside view of adult right valve; shell near the dorsal 

margin is missing. Paratype, USNM 162809.

15. Outside view of right valve. Paratype, USNM 162810. 

11, 12, 16. Petrobrasial sp. (p. B7).

11, 12. Muscle-scar patterns of a right valve interior and left 

valve exterior; approximately X 120. Figured specimens, 

USNM 162811. Photographs by D. H. Massie.

16. Lateral view of broken left valve. Figured specimen, USNM

162812. 

17-20. "Paracypridea" sp. (p. B7).

17. Interior view of broken left valve. Figured specimen, 

USNM 162814.

18. Outside view of right valve. Figured specimen, USNM

162813.

19. 20. Scanning electron micrograph of outside of a partly 

exfoliated right valve to show muscle-scar pattern on steinkern, 

approximately X 36, and enlargement of muscle-scar area, 

approximately X 90. Figured specimen lost. Micrographs by 

D. H. Massie.

U.S. GOVERNMENT PRINTING OFFICE: 1969 O 359-232
GEOLOGICAL SURVEY PROFESSIONAL PAPER 643-B PLATE 2

18 20 

CYPRIDEA (BISULCOCYPRIDEA), PETROBRASIA1, AND "PARACYPRIDEA'