An Unusual Lower Cambrian 

Trilobite Fauna from 

Nevada

GEOLOGICAL SURVEY PROFESSIONAL PAPER 483-F

An Unusual Lower Cambrian 

Trilobite Fauna from 

Nevada

By ALLISON R. PALMER

CONTRIBUTIONS TO PALEONTOLOGY

GEOLOGICAL SURVEY PROFESSIONAL PAPER 483-F

Twelve species representing the Olenellidae, 

Oryctocephalidae, Ogygopsidae, Dorypygidae, 

Zacanthoididae^ and Ptychopariidae are 

described and figured

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

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

The U.S. Geological Survey Library has cataloged this publication as follows:

Palmer, Allison Ralph, 1927-

An unusual Lower Cambrian trilobite fauna from Nevada. 

Washington, U.S. Govt. Print. Off., 1964.

iii, 14 p. 3 plates, map, diagr. 30 cm. (U.S. Geological Survey. 

Professional Paper 483-F)

Contributions to' paleontology. Bibliography : p. 12.

1. Trilobites. 2. Paleontology Nevada. 3. Paleontology Cambrian. I. Title. (Series)

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

Washington, B.C. 20402
CONTENTS

Page

Abstract.______________-__________________-________-__-__________-_-___----_----_-----__--- Fl

Introduction.______________________________-_______________-_______--___-____---__--_------- 1

Systematic paleontology_______-__________________________________-__..___----_---_----------- 2

Olenellidae-- _________________________________________________________________ 2

Dorypygidae.-____-_-___-_-________-__-___-___________-_-_--___-_--_----_--_-------_--- 5

Ogygopsidae_ _ __________________________________________________________________________ 6

Oryctocephalidae.__--_____-_____________________________-______-_____-__--_----_----_-- 7

Zacanthoididae ____-_______-_______________________________-____-____----__-_---------_- 8

Ptychopariidae_________________________________________________________________________ 11

Position uncertain_____________________________________________________________________ 11

References.________________________________________________________________________________ 12

Index_^______________________________________________________________ 13

ILLUSTRATIONS

[Plates follow index]

PLATE 1. Olenellidae, Oryctocephalidae.

2. Ogygopsidae, Dorypygidae.

3. Zacanthoididae, Ptychopariidae, position uncertain.

FIGURE 1. Map showing the locality of the fossil collection described in this report.

2. Position of described fauna in regional stratigraphic context-_________

Page

Fl

2

ill

CONTRIBUTIONS TO PALEONTOLOGY

AN UNUSUAL LOWER CAMBRIAN TRILOBITE FAUNA FROM NEVADA

By ALLISON R. PALMER

ABSTRACT

A fauna of at least 12 species of trilobites, from lower Cambrian rocks in Esmeralda County, Nev., constitutes the largest 

single assemblage of trilobites yet described from Lower 

Cambrian beds in North America. Well-preserved specimens 

of the Olenellidae, Oryctocephalidae, Ogygopsidae, Dorypygidae, 

Zacanthoididae, and Ptychopariidae are present. New taxa 

include Paedeumias granulatm n. sp.; GoWfieldia pacifica n. 

gen., n. sp.; Bonn/Id caperata n. sp.; Zacanthopsig contractus n. 

sp.; ZacantJiopsina eperephes n. gen., n. sp.; and Stephenaspist 

a/vitus n. sp.

INTRODUCTION

During reconnaissance geologic mapping of Esmeralda County, Nev., J. P. Albers and J. H. Stewart, of 

the U.S. Geological Survey discovered many localities 

of fossiliferous Lower Cambrian rocks. Collections 

from most of these localities were submitted to me for 

examination. In 1960 a collection from one of these 

localities (fig. 1) was found to contain an association 

of nonolenellid trilobites of Middle Cambrian aspect 

together with undoubted olenellids. In 1961 I was 

guided to this locality by J. H. Stewart and obtained 

a large supplemental collection. That collection is the 

principal source of the specimens described here.

Lower Cambrian trilobite collections from the Western States rarely contain assemblages of more than half 

a dozen species. Most of the trilobites in any one collection are olenellids, although occasionally a simple 

ptychoparioid or a species of Bonnia or of Zacanthopsis 

may be present. Barely are the specimens well preserved. Thus, the discovery of an excellently preserved 

Lower Cambrian trilobite assemblage that contains at 

least 10 genera representing at least 6 families can be 

properly termed unusual.

The fossil-bearing beds (USGS Colln.3T48-CO) crop 

out in a series of low north-facing hills about 3 miles 

southeast of the junction of Nevada Highways 3 and 

71 south of Goldfield, Nev., and about 5 miles northeast 

of Gold Point in the SWV* sec. 28, T. 6 S., E. 42 E., 

Goldfield (1: 250,000) quadrangle, Nevada. The trilobites are preserved in dark-gray limestone beds less than 

6 inches thick that are characterized by well-rounded 

grains of quartz sand "floating" in the limestone matrix 

or concentrated in the lower part of the beds. These

117°

37°

NYE

FIGURE 1. Map showing the locality of the fossil collection described in this report.

beds are about 40 feet above a 45-foot-thick brown 

sandstone unit (Stewart, written communication, June 

1963). The sandy limestones have the characteristics 

of a rock type that is found in the lower part of the 

Saline Valley Formation (Nelson, 1962) just above a 

basal sandy or quartzite unit. Nelson subsequently 

visited this locality and confirmed the identification of 

the fossiliferous beds as the lower part of the Saline 

Valley Formation. Nelson also examined stratigraphically important sections in the Last Chance Range, 

Calif, (fig. 1), in company with J. H. Stewart and me in 

April 1963. It was determined that the basal quartzites 

of the Saline Valley Formation in the northern part of 

the range correlate with the Zabriskie Quartzite exposed in the southern part of the range. Collections 

from the upper part of the Saline Valley Formation 

have yielded species of the olenellid genus BristoUa. 

This is a characteristic and locally abundant genus in the 

Lower Cambrian part of the Carrara Formation, which 

is above the Zabriskie Quartzite, in the Death Valley

Fl
CONTRIBUTIONS TO PALEONTOLOGY

region. Thus, the fauna described here from the lower 

part of the Saline Valley Formation seems firmly established in the upper part of the Lower Cambrian in a 

position slightly older than that yielding the Bristolia 

fauna (fig. 2).

Last Chance 

Range

Vw^VV^tyv/yyv^/

Mule 

Spring

Limestone

Saline 

Valley 

Formation

Basal 

sandy member

An/UlWVM

_ Bristol/a _

Fauna described 

/in this report

Death Valley 

region

v/vs/vVWvVVvV

Lower limestone member

Carrara 

Formation

Zabriskie 

Quartzite

AnWuVMA

FIGURE 2. Correlation of parts of the Lower Cambrian formational sequences between the Last Chance Range and 

the Death Valley region, California, showing the approximate stratigraphic position of the fauna described in this 

report.

This trilobite assemblage cannot be compared at present with any other known assemblage in the Cordilleran region of North America. Lower Cambrian assemblages, which include various nonolenellids but 

fewer total species, have been described by Easetti 

(1948) from boulders in the Levis conglomerates of 

Quebec and by Eesser (1938) from limestones of the 

Austinville district, Virginia; but the fauna described 

here is by far the largest and most varied assemblage of 

Lower Cambrian trilobites yet described from North 

America. Entirely new forms are Zacanthopsina 

eperephes n. gen., n. sp., and Stephenaspis ? avitus n. sp. 

Typical Lower Cambrian species include Paedewnias 

granulatus n. sp., Wanneria cf. W. walcottana (Wanner) , Zacanthopsis contractus n. sp., Bonnia caperata n. 

sp., and Syspacephalus sp. In addition, the fauna includes Ogygopsis batis (Walcott), which represents a 

long-ranging genus that until recently (Nelson, 1963) 

was not definitely known to occur in Lower Cambrian 

beds; the fauna also includes the first Cordilleran record of Lower Cambrian representatives of Olenoides 

(at least two unnamed species) and of the family Oryctocephalidae (Gold-fieldia pacifica n. gen., n. sp.). It 

is rather surprising that eodiscids, described by Easetti

(1948) from the Lower Cambrian of Quebec and reported by him (Easetti, 1951) from the Lower Cambrian 

of British Columbia, are absent from this assemblage. 

Sampling of the Lower Cambrian faunas of the Western States has just begun, however, and an increase in 

our knowledge of these older trilobite faunas can be 

anticipated.

SYSTEMATIC PALEONTOLOGY

The descriptive terminology used for the olenellids 

is the same as that used earlier by me. (See Palmer, 

1957.) Descriptive terminology for the other trilobites 

is that found in the illustrations or glossary of the 

Treatise on Invertebrate Paleontology, Part O, Arthropoda 1 (Harrington and others, 1959). Familial or 

generic assignments that have no comment indicate 

acceptance of the classification in the treatise. Locality data and identifying locality numbers for figured 

specimens are recorded in the Cambrian-Ordovician 

locality catalog of the U.S. Geological Survey. All 

figured specimens, unless otherwise indicated, are from 

U.S. Geological Survey collection 3748-CO.

Order REDLICHIIDA Bichter 

Family OLENELLIDAE Vogdes 

Genus PAEDETJMIAS Walcott

Paedeumias Walcott, 1910, p. 304; Resser, 1928, p. 4; Poulsen, 

1932, p. 26; Resser and Howell, 1938, p. 225; Poulsen, 1959, 

p. 192.

Type species. Paedeumias transitans Walcott, 1910, 

p. 305, pi. 34, fig. 1.

Diagnosis. Olenellidae having glabella distinctly 

separated from cephalic 'border by preglabellar field 

but generally connected to border by narrow median 

ridge. Cephalic border wirelike. Palpebral lobes 

long; line connecting posterior tips crosses glabella 

posterior to midlength of preoccipital segment. Intergenal spines short and directed nearly straight 

posteriorly in mature holaspids; near genal spines.

Discussion. Walcott originally diagnosed Paedeumias as a genus differing from Olenellus by having 

thoracic segments posterior to the spine-bearing 15th 

segment. Eesser (1928) correctly referred one of 

Walcott's best paratypes (Walcott, 1910, pi. 33, fig. 1) 

to Olenellus, thus negating the generic differentiation 

proposed by Walcott. However, Resser then presented 

a new diagnosis based on cephalic features. With some 

modifications and additions, this is the concept of 

Paedeumias presently in use. Eesser and Howell 

(1938) noted the distinctive narrowness of the cephalic 

border as a generic feature. The usefulness of this 

characteristic was demonstrated statistically by Palmer 

(1957) on a silicified sample of associated species of 

Olenellus and Paedeumias.
LOWER CAMBRIAN TRILOBITE FAUNA FROM NEVADA F3

Several olenellid species share the characteristics of 

long palpebral lobes, narrow cephalic border, and 

distinct preglabellar field but differ in sagittal length 

of the preglabellar field, length of the palpebral lobe, 

ornamentation, and other features. They constitute a 

supraspecific taxon (Paedeumias} that differs from 

another taxon of comparable rank (Olenellus] in which 

the species have a characteristically broader border. 

The arguments of Bell (1931) and Shaw (1955) for 

suppression of Paedeumia,s as a synonym of Olenellus 

are no longer valid. Discussion of subgeneric versus 

generic status for Paedeumias is moot, at least until an 

acceptable classification is presented for the Olenellidae. 

Therefore, Paedeumias is considered here as a distinctive genus of the Olenellidae.

Paedeumias granulatus n. sp. 

Plate 1, figures 1-10

Description. Cephalon subsemicircular in outline, 

gently to moderately convex transversely and longitudinally. Anterior and lateral margins evenly curved. 

Posterior margin straight and perpendicular to axial 

line between intergenal spines; directed slightly anterolaterally between intergenal and genal spines. 

Genal spine slender, directed straight posteriorly; 

length slightly more than one-half distance from genal 

angle to base of occipital segment. Intergenal spine 

present only as node on posterior margin; separated 

from genal spine by distance slightly less than three 

times basal width of genal spine.

Glabella prominent and has well-defined glabellar 

furrows; separated from border by sagittal distance 

equal to slightly less than twice sagittal length of 

border and connected to border by low, poorly defined 

median ridge. Glabellar segments generally defined 

only at distal ends. Occipital and preoccipital furrows deep, narrow at sides of glabella, hardly apparent 

across top. The two remaining furrows represented by 

deep narrow slots isolated from sides of glabella by 

ocular lobe or by posterolaterally directed distal ends 

of first leg segment. Posterior pair of slots generally 

shorter transversely than anterior pair. A moderately 

well-defined furrow may connect anterior pair of slots 

and outline posterior margin of frontal lobe of glabella. 

Larger cephala (pi. 1, fig. 10) consistently bear small 

dimple on axial line just anterior to this furrow on 

posterior part of frontal lobe. Occipital ring has distinct node on axial line at posterior margin.

Ocular lobes long, slender, gently curved; posterior 

tips opposite midlength of occipital segment and barely 

separated from it by narrow posterior extension of 

infraocular cheek. Each ocular lobe has distinct furrow delineating a narrow lateral rim along entire

length of lobe; transverse width of this rim about onefourth width of ocular lobe.

Interocular area narrow and depressed below glabella and ocular lobe; has moderately to poorly defined 

hump in posterior part and, on largest specimens, distinct veination. Greatest width about equal to width 

of ocular lobe.

Extraocular cheek broad and nearly flat and has 

moderately well-defined radial veination; greatest 

width about one-fourth or slightly less than one-fourth 

greatest width of cephalon. Cephalic border narrow; 

width one-fifth or less than one-fifth width of extraocular cheek.

External ornamentation of most specimens consists 

of closely spaced fine granules, often apparent only 

after whitening, on all parts except furrows and cheek 

area in front of glabella. Some large specimens have 

external surface nearly smooth or have irregular short 

terrace lines on all observed parts.

Hypostome has anterior lobe of middle body inflated. 

Anterior margin slightly acuminate on axial line, rim 

narrow, upturned. Middle furrows deep. Posterior 

lobe of middle body reduced; six pairs of marginal 

spines on specimen 6 mm in length.

Discussion. This distinctive species of Paedeumias 

differs from all others so far described by the granular 

ornamentation of many specimens and by the welldefined furrow on the lateral parts of the ocular lobes. 

The intergenal spines are farther from the genal spines, 

the ocular lobes are longer, and the interocular areas 

are narrower than in many other species of the genus.

All known specimens of this species are broken, but 

parts of at least 50 cephala are in the collection. These 

cephala range from 2 mm to about 20 mm in sagittal 

length. The small meraspid specimens do not have a 

well-defined furrow on the ocular lobe, but the granular 

ornamentation can be seen on the extraocular cheeks. 

The principal variable features of the holaspid specimens are the ornamentation and the definition of the 

furrow outlining the posterior part of the frontal lobe 

of the glabella.

Genus WANNERIA Walcott

Wanneria Walcott, 1910, p. 296; Poulsen, 1932, p. 35; Lake, 1937, 

p. 245; Resser and Howell, 1938, p. 227; Poulsen, 1958, 

p. 16; Poulsen, 1959, p. 197.

Type species. Olenellus (Holmia] walcottanus 

Wanner, 1901, p. 267, pi. 31, figs. 1, 2; pi. 32, figs. 1-4.

Diagnosis. Olenellidae in which cephalon has genal 

spines at posterolateral corners; intergenal spines not 

apparent. Glabella has expanded frontal lobe reaching 

to or nearly to inner edge of border. Ocular lobe arcuate and has well-defined longitudinal furrow. Ex-
F4 CONTRIBUTIONS TO PALEONTOLOGY

ternal surfaces of all parts generally have characteristic 

strong reticulate meshwork of raised ridges.

Anterior width of thorax nearly as great as width 

of cephalon; third segment not macropleural.

Wanneria cf. W. walcottana (Wanner) 

Plate 1, figures 11-13, 15

Wanneria walcottana Wanner. Walcott, 1910, p. 302, pi. 30, 

figs. 1-12.

Description. Cephalon subsemicircular in outline, 

gently to moderately convex transversely and longitudinally. Anterior and lateral margins evenly curved. 

Posterior margin nearly straight; curved gently backward distally to base of genal spine. Genal spine moderately short, not divergent from lateral margin of 

cephalon; length on small holaspid (sagittal length of 

cephalon 12 mm) slightly less than distance from inner 

edge of spine to base of occipital segment. Separate 

intergenal spine not apparent.

Glabella prominent, reaching to or nearly to inner 

edge of border. Glabellar furrows well defined, deepest distally, shallow across axial line. Distal ends of 

first leg segment directed for short distance posterolaterally outside of anterolateral ends of second leg segment.

Ocular lobes strongly curved, moderately close to glabella; line connecting posterior tips passes about over 

occipital furrow. Distinct longitudinal furrow on ocular lobe, delineating narrow lateral rim.

Interocular area depressed; greatest width opposite 

preoccipital furrow and aUout equal to transverse width 

of ocular lobe on same line.

Extraocular cheek gently to moderately convex; has 

moderately wide well-defined lateral and posterior borders. Border furrows joined at moderately acute genal 

angle. Width of lateral border about one-third greatest 

distance from lateral margin of eye to border furrow.

External surfaces of smaller specimens covered with 

coarse ornamentation of poorly formed reticulations 

mixed with irregularly raised terrace lines, so that 

whitened specimens appear in part to be granular. 

Large specimens have coarse raised reticulate network 

on all parts.

Discussion. This species, which is less common than 

Paedeumias granulatus, is represented by only two incomplete small cephala, a large hypostome, and many 

fragments of large specimens that display well-defined 

reticulate ornamentation. The species is not well 

enough represented to be separately named. However, 

it differs from the Mexican species, Wanneria buelnaensis Lochman (in Cooper and others, 1952), by having

the genal spines at the posterolateral cephalic corners. 

W. buelnaensis is here considered a distinct species rather than a variety of W. walcottana (Wanner) because 

of the consistently advanced position of its genal spines. 

The general shape of the cephalon of the species described here is most like that of W. nathorsti Poulsen 

from Greenland. However, it differs from W. natliorsti 

by having deeper anterior glabellar furrows and by having the reticulate ornamentation less well defined at 

comparable stages of growth.

Small specimens that have relatively longer palpebral 

lobes than have associated large specimens of Wanneria 

ivalcottana in Pennsylvania were considered by Walcott 

to show that the size of the palpebral lobe relative to 

cephalic size decreased as individuals became larger 

(Walcott, 1910, p. 296, pi. 30, figs. 3, 4). Resser and 

Ho well (1938, p. 229, pi. 8, fig. 10) assigned Walcott's 

small illustrated specimens to Esmeraldina macer (Walcott) without comment. The holotype of E. macer, 

which is from a different locality, is a small, nearly complete specimen having a narrow thorax. The posterior 

cephalic margin of this specimen is not well preserved, 

and it is not possible to determine whether morphologic 

features that usually indicate a narrow thorax are present. Walcott's small specimens are associated with 

large specimens of W. walcottana which has a broad 

thorax. These small specimens have posterior cephalic 

outlines essentially like those of the large specimens 

and there is no compelling reason for removing them 

from the species sample solely because of small size. 

The small cephala from Nevada also have long palpebral lobes and do not differ in any other observable 

feature from W. walcottana. Therefore, they may be 

coiispecific with the specimens from Pennsylvania.

The ornamentation on large specimens in the Nevada 

collection is unusual. Fragments of the exoskeleton, 

when viewed from below, show a striking series of 

perforations arranged in a reticulate pattern exactly 

paralleling the pattern of reticulate ridges on the external surface (pi. 1, fig. 11). The exoskeleton breaks 

along the margins of the reticulations, showing that the 

perforations continue upward into the exoskeleton as 

tubes that do not reach the dorsal surface. These tubes 

outline polygonal plates, which make up the entire exoskeleton. This exoskeletal structure may well be a characteristic feature of the genus Wanneria. Similar perforations from the ventral surface outline polygonal 

plates on scraps associated with one of the paratypes of 

W. buelnaensls Lochman, and specimens of W. walcottana that are slightly crushed show breakage along lines 

of weakness around the margins of polygons.
LOWER CAMBRIAN TRILOBITE FAUNA FROM NEVADA F5

Order CORYNEXOCHIDA Kobayashi

Family DORYPYGIDAE Kobayashi

Genus BONNIA Walcott

Corynexochus (Bonnia) Walcott, 1916, p. 325.

Bonnia Walcott. Raymond, 1928, p. 309; Resser, 1936, p. 6; 

Resser, 1937, p. 44 ; Lermontova, 1940, p. 142 ; Lochman, 1947, 

p. 68; Rasetti, 1948, p. 14: Lermontova, 1951, p. 118; 

Pokrovskaya, 1959, p. 135; Poulsen, 1959, p. 217.

Type species. Bathyur-us parvulus Billings, 1861, p. 

953, fig. 361.

Discussion. Because this genus has been defined 

many times, there is now little controversy about its 

included species. Kasetti (1948) has pointed out, however, that species cannot be accurately defined without 

knowledge of well-preserved associated parts because 

the primary distingushing characteristics of external 

ornamentation are often different on the cranidium and 

on the pygidium of the same species. Secondary 

characteristics of taxonomic value are shape of glabella, 

particularly at its anterior end; depth of occipital 

furrow; size and shape of occipital ring; depth of 

glabellar furrows; depth of pleural and ring furrows on 

pygidium; number and length of pygidial border spines.

Bonnia caperata n. sp. 

Plate 2, figures 11-16

Description. Glabella well defined, moderately 

arched transversely and longitudinally, expanded 

slightly and evenly forward nearly to border; anterolateral corners strongly rounded; anterior end blunt. 

Glabellar furrows apparent only as shallow indentations adjacent to axial furrows. Occipital furrow deep 

at sides, shallow across axis. Occipital ring of nearly 

constant width and nearly flat; distinct axial node or 

spine absent. Frontal area consists only of narrow 

gently convex border. Fixed cheek gently convex, 

slightly downsloping; width, exclusive of palpebral 

lobe, slightly less than one-half basal glabellar width. 

Palpebral lobes well defined by change in slope of 

cheek surface, somewhat sunken, gently curved; length 

slightly more than one-third length of glabella exclusive 

of occipital ring. Line connecting midlengths of 

palpebral lobes crosses glabella slightly posterior to 

glabellar midlength. Ocular ridge low, poorly defined, 

parallel with and close to border; contact with glabella 

marked by shallow fossula in axial furrow. Posterior 

limb broad; tip bluntly rounded; transverse length 

slightly more than basal glabellar width. Posterior 

border furrow deep near glabella, shallow laterally. 

Posterior border has no noticeable geniculation.

Course of anterior section of facial suture short, 

slightly convergent anteriorly in gentle curve from 

palpebral lobe to anterior margin. Course of posterior

section strongly divergent behind palpebral lobes, then 

curved strongly backward to posterior margin.

Free cheek narrow and has gently curved lateral 

margin and short blunt genal spine; width at eye about 

one-eighth length of cheek including genal spine. 

Border poorly defined, convex, wider than ocular platform. Posterior sutural margin intersects shallow 

lateral border furrow.

Pygidium subsemicircular in outline, slightly flared 

at anterolateral corners. Axis well defined, slightly 

tapered backward, strongly rounded at end; reaches to 

inner edge of border. Four ring furrows indicated 

posterior to articulating furrow; only first and, in 

some specimens second furrows continuous across axis. 

Pleural fields crossed by three or four shallow pleural 

furrows that do not cross border. Border narrow, 

convex, and of nearly constant width. One pair of 

short anterolateral border spines present.

External ornamentation variable. Glabella covered 

with concentrically arranged irregular terrace lines except over areas of muscle scars. Fixed cheeks may have 

irregular ornamentation of terrace lines in all places 

less well defined than on glabella; or, if terrace lines 

are subdued, the cheeks have scattered fine pits. Top 

of occiptal ring has moderately prominent irregular 

terrace lines. Palpebral lobes, tips of posterior limbs, 

and ocular platform of free cheek smooth or covered 

with scattered fine pits. Border of cranidium and free 

cheek has subparallel terrace lines. Pygidium either 

nearly smooth or has scattered fine pits on pleural fields 

and irregular coarse ridges on top of axis or irregular 

anastomosing ridges on all parts.

Discussion. Although many species of Bonnia have 

been named, most are represented by material inadequate for meaningful comparison. The adequately 

represented Cordilleran species are B. columbensis 

Kesser and B. fieldensis (Walcott). Both lack significant external ornamentation, although specimens of 

B. fieldensis have scattered fine pits. In addition, the 

first pleural furrows on the pygidia of both species 

continue across the border to the pygidial margin instead of stopping at the border furrow as in B. caperata. 

Species of Bonnia from other regions that are ornamented with terrace lines differ from B. caperata by 

having associated granular ornamentation and, generally, a differently shaped glabella and occipital ring. 

Bonnia brennus (Walcott) (Kasetti, 1948, pi. 3, figs. 

16-25) is perhaps most typical of these forms. 

Genus OLENOIDES Meek

Olenoides spp. 

Plate 2, figures 7-10

Discussion. At least two species have pygidia possessing the characteristic border spines and well-defined
F6 CONTRIBUTIONS TO PALEONTOLOGY

pleural and interpleural furrows of Olenoides. One 

has four pairs of long slender border spines (pi. 2, figs. 

9, 10), and the other has four pairs of short slender 

border spines (pi. 2, fig. 8). Both species have granular 

external surfaces.

All five fragmentary specimens of the short-spined 

species are from a small collection, USGS collection 

3655-CO. This was the orignal collection submitted 

by Stewart. A later collection (3748-CO) from the 

locality yielded a large fauna, including six specimens 

of the long-spined species. Other species in collection 

3655-CO are the same as those in the later collection. 

At the two times of collection, apparently slightly different beds were collected from, as is reflected by the 

different Olenoides species. This was confirmed by 

Stewart (written communication, June 1963), who reevaluated his field notes after our collecting trip.

Four-spined species of Olenoides having a granular 

surface have been described from beds of Early and 

Middle Cambrian age. However, all such species are 

represented by so few individuals that variability cannot be determined, and minor differences between the 

known small samples cannot 'be evaluated. Cranidia 

that have a granular surface are associated with the 

long-spined specimens discussed here and may belong 

to the same species. However, until infraspecific variability of the pygidia, which have the principal characteristics of specific value, can be determined, specific 

identification of the specimens illustrated here will be 

meaningless.

Family OGYGOPSIDAE Rasetti 

Genus OGYGOPSIS Walcott

Offyyoipsis Walcott, 1889, p. 466; Walcott, 1916, p. 375; Raymond, 

1912, p. 116; Shimer and Shrock, 1944, p. 613; Rasetti, 1951, 

p. 190 ; Rasetti, 1959, p. 219.

Taxioura Resser, 1939, p. 62; Shimer and Shrock, 1944, p. 617.

Type species. Ogygia klotzi Kominger, 1887, p. 12, 

pl.l,fig.l.

Description. Isopygous opisthoparian trilobites; 

cephalon subsemicircular in outline,' gently to moderately convex transversely and longitudinally. Glabella 

long, large, reaching to or nearly to border, strongly 

rounded at front, moderately convex transversely and 

longitudinally; sides subparallel or bowed slightly outward. Glabellar furrows generally not apparent on 

uncrushed material. Occipital furrow moderately well 

defined, nearly straight. Occipital ring does not have 

obvious nodes or spines. Frontal area short; sagittal 

length less than one-eighth that of glabella. Border 

narrow, poorly defined by change in slope. Fixed 

cheeks gently convex, slightly downsloping; transverse 

width, exclusive of palpebral lobes, slightly less than 

one-half basal glabellar width. Palpebral lobes gently

arcuate, welt defined by shallow palpebral furrows, generally connected to glabella by low ocular ridge; length 

about one-third length of glabella exclusive of occipital 

ring. Line connecting midlengths of palpebral lobes 

passes over glabella posterior to glabellar midlength. 

Posterior limbs tapered laterally to blunt point; transverse length slightly greater than basal glabellar width.

Course of anterior section of facial suture nearly 

straight forward from palpebral furrow to border, then 

curved gently inward to cut anterior margin near 

anterolateral cranidial corners. Posterior section 

straight or slightly convex from palpebral lobes to 

posterior margin.

Lateral border of free cheek moderately defined by 

shallow border furrow that almost disappears near base 

of genal spine. Border distinctly narrower than ocular 

platform. Contact between ocular platform and eye 

surface marked by low collar that is separated from 

ocular platform Dnly by sharp change in slope. Genal 

spine moderately short; length about equal to length of 

posterior section of facial suture.

Thorax consists of eight segments; tips of each segment have single short laterally directed slender spines. 

Axial rings do not have well-defined nodes or spines. 

Width of pleural regions distinctly greater than width 

of axis.

Pygidium subsemicircular in outline; length slightly 

more than one-half greatest width. Axis well defined, 

slender, reaching nearly to posterior margin; has seven 

or more complete ring furrows posterior to articulating 

furrow; width slightly less than one-fourth greatest 

width of pygidium. Pleural regions broad, gently convex, crossed by five or more moderately deep pleural 

furrows that reach to inner edge of narrow, convex 

border of nearly constant width. Interpleural furrows 

also present on some specimens. Margin of pygidium 

smooth or has one or more pairs of short, sharp spines.

Discussion. This genus is easily recognizable by the 

combination of a cranidium having a prominent subparallel-sided glabella reaching almost the entire 

cranidial length and a large pygidium having a narrow 

axis and border and well defined ring and pleural furrows. Kasetti (1951, p. 191) concluded that Taxioura 

(Resser, 1939) was a subjective synonym of Ogygopsis 

after comparing the type species, T. typicalis Resser, 

with 0. klotzi. Resser's second species of Tawioura, T. 

magna, was founded on an incorrect association of parts 

and is here removed from Ogygopsis. The pygidium of 

this species (Resser, 1939, pi. 14, figs. 1, 2) agrees in all 

morphological details with T. typicalis. The holotype 

and paratype cranidia of T. magna, all have coarse granular external ornamentation and a short occipital spine. 

These cranidia probably belong to Olenoides maladensis
LOWER CAMBRIAN TRILOBITE FAUNA FROM NEVADA F7

Resser, a species from the same fauna whose pygidia 

have a coarse granular surface.

Nelson noted (1963, p. 246) that Bathyuriscus batis 

Walcott, from Lower Cambrian beds in western Nevada, 

is actually a species of Ogygopsis. Other species presently assigned to Ogygopsis are 0. spinulosa Rasetti and 

Taxioura elongata McLaughlin and Enbysk.

Specimens of all species of Ogygopsis except 0. 

elongata (McLaughlin and Enbysk, 1950) were examined for this study. Two features of the pygidium 

were found to be valid for species discrimination. All 

species except 0. klotzi have at least one pair of marginal pygidial spines, and the number of pairs of spines 

is constant for each species. Also, the number of welldefined pleural furrows is constant for each large collection studied. If these characters are used in 

combination, at least five species of Ogygopsis can be 

recognized. Pygidia of 0, Motzi (Rominger) lack marginal spines and have seven well-defined pleural furrows. Pygidia of 0. typicalis (Resser) have one pair of 

anterolateral spines and seven well-defined pleural furrows. Pygidia of 0. spinulosa Rasetti have at least 

seven pairs of marginal spines, indications of two additional pairs of marginal spines and seven well-defined 

pleural furrows. These three species are of Middle 

Cambrian age. Pygidia of 0. batis (Walcott) from 

Lower Cambrian beds have one pair of anterolateral 

marginal spines and five or six well-defined pleural furrows. Pygidia of a second, undescribed Lower Cambrian species from Esmeralcla County, Nev., have six 

or seven pairs of marginal spines and five or six welldefined pleural furrows. Thus, the principal character 

of stratigraphic value seems to be the number of pleural 

furrows. No Lower Cambrian specimens have more 

than six pleural furrows, whereas all Middle Cambrian 

specimens have seven pleural furrows.

Ogygopsis elongata (McLaughlin and Enbysk) may 

be a synonym of 0. typwalis (Resser). Well-preserved specimens from the Metaline Limestone in the 

type region for 0. elongata have all the characteristics 

of 0. typicalis, and the differences in proportion used 

for discrimination of the distorted specimens of 0. 

elongata may not be valid.

In addition to the easily recognizable pygidial differences, each species may have characteristic external ornamentation. Only Ogygopsis Motzi, 0. typicalis, and 

0. batis are represented by specimens well enough preserved to check this character. The external surfaces 

of all well-preserved specimens of 0. klotzi are smooth 

except for low terrace lines on the margins of the craniclium, free cheek and pygidium. 0 typicalis has a 

finely formed "fingerprint" pattern of terrace lines on 

the glabella and an irregular close-spaced pattern of

terrace lines on other parts of the cranidium and free 

cheeks. The terrace lines on the pygidium form a fine 

meshwork of irregular polygons. On 0. batis the terrace lines on the cheek regions of the cephalon, as well 

as those on the pygidium form an irregular meshwork 

of tiny polygons; in addition, the surfaces of all parts 

are covered with numerous fine pits. This ornamentation is apparent only after whitening of well-preserved 

specimens.

Ogygopsis batis (Walcott)

Plate 2, figures 1-6 

Bathyuriscus batis Walcott, 1916, p. 337, pi. 48, figs. 4, 4a.

Diagnosis. Species of Ogygopsis in which cranidium has moderately well-defined anterior border separated from glabella by narrow brim; course of border 

furrow an even curve, uninterrupted and undeflected by 

front of glabella. Pygidium has one pair of short, 

sharp, anterolateral border spines and no more than six 

well-defined pleural furrows. Interpleural furrows 

shallow or absent. External surfaces of pleural regions 

of cephalon, thorax, and pygidium, and tops of axial 

rings and occipital ring have fine polygonal network of 

terrace lines. Surface of glabella has fine "finger print" 

ornamentation of terrace lines. All parts finely pitted.

Discussion. The type of Ogygopsis batis is a 

poorly preserved specimen from slightly metamorphosed Lower Cambrian rocks at Miller Mountain, Nev. 

Unfigured paratype and topotype specimens show a 

single pair of anterolateral pygidial spines and fewer 

than seven pleural furrows. Because these characteristics seem to be of specific value for the well-preserved 

specimens described here, these specimens are considered conspecific with the specimens from Miller 

Mountain.

Family ORYCTOCEPHALIDAE Beecher 

Genus GOLDFIELDIA n. gen.

Type species. Goldfieldia pacific® n. sp.

Diagnosis. Oryctocephalidae which have glabella 

poorly defined at front, narrowest at occipital ring; 

frontal lobe has median depression in anterior part. 

Posterior pair of glabellar furrows connected laterally 

to axial furrows. Cranidial border wirelike.

D'iscusswn. This is a monotypic genus. Its relations to other trilobites are discussed after the description of the type species.

Goldfieldia pacifica n. sp. 

Plate 1, figures 14, 16-18

Description. Oryctocephalidae which have cranidium subtrapezoidal in outline, gently convex transversely and longitudinally; width between anterior sec-
F8 CONTRIBUTIONS TO PALEONTOLOGY

tions of facial sutures about two-thirds width between 

tips of posterior limbs. Anterior margin gently curved.

Glabella well defined at sides; axial furrows subparallel between occipital and preoccipital furrows, divergent slightly forward between preoccipital and 

second glabellar furrows, where divergence increases 

width of glabella by about one-fourth, then subparallel 

to junction with ocular ridge. Front of glabella anterior to ocular ridges not clearly defined. Four pairs of 

lateral glabellar furrows present but not connected 

across top of glabella; posterior and anterior pairs connected laterally to axial furrows; second pair from rear 

consists of isolated pits. Frontal glabellar lobe has 

shallow median depression on anterior part. Occipital 

furrow shallow; occipital ring has small median node.

Frontal area gently concave; border narrow, wirelike.

Fixed cheek broad, gently convex, horizontal; width, 

exclusive of palpebral lobe, about equal to basal glabellar width. Palpebral lobe well defined by sharp 

change in slope, slightly curved, at distinct angle to 

axial line; length about equal to basal glabellar width; 

line connecting posterior tips passes over preoccipital 

furrow. Ocular ridge poorly defined, reaching axial 

furrow about opposite anterior glabellar furrow.

Posterior limbs moderately long, tips rounded; transverse length nearly twice basal glabellar width. Posterior border furrow moderately deep distally, becoming 

shallower toward glabella and nearly disappearing just 

before reaching axial furrow.

Course of anterior section of facial suture straight 

forward from palpebral lobe. Course of posterior section of facial suture moderately to strongly convex; 

strongly divergent immediately behind palpebral lobe.

External surfaces of all parts of cranidium smooth.

Other parts not known.

Discussion. The most distinctive features of this species are the poorly defined front of the glabella, the median depression in the anterior part of the frontal 

glabellar lobe, the wirelike cranidial border, the glabellar shape, and the posterior pair of glabellar furrows 

connected laterally with the axial furrows. No other 

oryctocephalid species described possesses this combination of characteristics. Forms such as Lancmtria 

Toddyi (Walcott) and TonkineM-a valida Chernysheva 

have a wirelike border on the front of the cranidium in 

addition to a broader border that is in contact with the 

glabella. Nothing on the cranidia of Goldfieldia 

 pacified indicates the presence of any border other than 

the wirelike one. L. roddyl is the only previously described Lower Cambrian oryctocephalid, and the known 

specimens are rare and are deformed. The holotype of 

L. roddyi shows the apparent connection of the posterior glabellar furrows across the top of the glabella but 

no clear indication of their connection to the axial furrow. This character, plus the apparent presence of a 

broad cranidial border is sufficiently different from G. 

pac-ifi&a n. sp. to warrant placing the forms in different 

genera,

Family ZACANTHOIDIDAE Swinnerton

Genus STEFHENASFIS Basetti 

Stephenaspis Rasetti, 1951, p. 180; Rasetti, 1959, p. 229.

Type species. Steplienaspis bispinosa Rasetti, 1951, 

p. 181, pi. 10, figs. 1-6.

Diagnosis. Cephalon has slender anteriorly expanded glabella that reaches to narrow anterior border. 

Fixed cheeks narrow; width exclusive of palpebral lobes 

one-half or less than one-half basal glabellar width. 

Palpebral lobe long, slender, curved; anterior end 

separated from axial furrow by moderately narrow 

part of fixed cheek. Posterior limb slender; posterior 

fixigenal spine absent.

Pygidium subquadrate in outline; has prominent axis 

and gently convex pleural region lacking well-defined 

border. Posterolateral margin has pair of slender 

posteriorly directed spines.

Stephenaspis? avitus n. sp. 

Plate 3, figures 10-14

Description. Cranidium, exclusive of posterior 

limbs, subquadrate in outline and moderately convex 

transversely and longitudinally; width between palpebral lobes about equal to sagittal length. Anterior 

margin moderately curved. Frontal area constricted 

in front of glabella, divided laterally into brim and 

border by sharp change in slope. Glabella low, clearly 

defined, reaching onto border; gently and evenly expanded forward, anterolateral corners sharply rounded. 

Four pairs of lateral glabellar furrows present; posterior pair deepest, directed backward at acute angle 

to axial furrow; second pair nearly at right angles to 

axial furrow; anterior two pairs directed slightly 

anteriorly from axial furrow. Occipital furrow moderately deep at sides of glabella, shallower across axial 

line. Occipital ring nearly flat, moderately long sagittally; some specimens have low axial keel and all 

specimens have a short median spinule on posterior 

margin.

Fixed cheeks gently convex; width, exclusive of palpebral lobes, about one-half basal glabellar width. 

Palpebral lobes well defined by deep palpebral furrows, 

strongly curved, connected to axial furrows at junction 

with fourth pair of glabellar furrows by low ocular 

ridge that crosses moderately narrow part of fixed 

cheek; length of palpebral lobe slightly less than onehalf sagittal length of glabella.

Posterior limb long and slightly backswept and has 

bluntly rounded tip; transverse length generally
LOWER CAMBRIAN TRILOBITE FAUNA FROM NEVADA F9

slightly more than basal glabellar width. Posterior 

border furrow broad, deep.

Course of anterior section of facial suture slightly 

divergent forward from palpebral lobe to border, then 

sharply turned inward across border to merge imperceptibly with anterior margin. Course of posterior 

section of facial suture moderately convex from palpebral lobe to posterior margin.

Free cheek has moderately curved lateral margin 

continuing backward into short genal spine. Border 

narrow, well denned; width distinctly less than width 

of ocular platform. Lateral and posterior border furrows of even depth, joined in sharp curve at genal 

angle.

External surfaces of most parts covered with fine 

closely spaced granules generally apparent only after 

whitening.

Discussion. The general cranidial characteristics of 

this species, including the long anteriorly expanded 

glabella, the long palpebral lobes that have the anterior 

ends moderately separated from the axial furrows, and 

the posterior limbs that have no posterior fixigenal 

spines, are those of Stephenaspis. On 8.1 avitiis the 

facial sutures are less divergent forward and the cheek 

width between the anterior end of the palpebral lobe 

and the axial furrow is greater than on the genotype, S. 

bispinosa Rasetti. The genal spine on the free cheek 

is also somewhat shorter. However, without knowledge of the structure of the pygidium, which is of 

critical importance for generic identification in this 

group, the species described here cannot be definitely 

assigned to Stephenaspis. If the pygidia described on 

page F12 belong in S.? avitus, the trilobite resembles 

Poliellci denticulate*. (Rasetti, 1951, pi. 12, figs. 6-9). 

However, P. denticulata has distinctly narrower fixed 

cheeks adjacent to the anterior ends of the palpebral 

lobes.

Ptarmigania and Ptarmiganoides are two somewhat 

similar genera in which cranidia have long palpebral 

lobes and have a moderate distance between the anterior 

end of the palpebral lobe and the axial furrow. In 

both these genera, however, the genal spines are advanced, and the posterior limbs of the cranidia bear 

prominent posterior fixigenal spines. These characteristics are so much like those of Zacanthoides that both 

Ptarmigania and Ptamn iganoid&s probably should be removed from the Dolichometopidae, in which they were 

placed by Rasetti (1951) and by Poulsen (1959), and 

placed in the Zacanthoididae.

Genus ZACANTHOPSIS Resser

Type species. Olenoides lev is Walcott, 1886, p. 187, 

pi. 25, figs. 3,3a.

Description. Small corynexochid trilobites; total 

length of largest known specimen estimated as 25 mm. 

Cranidium subquadrate in outline, gently to moderately 

convex transversely and longitudinally. Glabella long, 

slender, expanded slightly at anterior end, bluntly 

rounded in front. Glabellar furrows poorly defined. 

Occipital furrow deep, straight. Occipital ring has 

slender posteriorly directed axial spine extending from 

posterior margin. Frontal area moderately short; 

sagittal length between one-third and one-fourth of 

sagittal length of glabella exclusive of occipital ring. 

Border moderately to poorly defined; where apparent, 

separated from glabella by narrow concave brim. 

Fixed cheeks broad, horizontal or gently upsloping, 

flat or gently convex; width, exclusive of palpebral 

lobes, about three-fourths basal glabellar width. Palpebral lobes long, strongly bowed, transversely convex, 

well-defined by palpebral furrows, generally slightly 

elevated above surface of fixed cheek; lateral margins 

vertical; anterior ends distinctly separated from axial 

furrows by moderately narrow part of cheek that is 

crossed by distinct ocular ridges. Transverse line 

through midpoints of palpebral lobes passes over 

posterior half of glabella. Posterior limbs short and 

have rounded tips barely extending laterally beyond 

palpebral lobes.

Course of anterior section of facial suture divergent 

forward from palpebral lobe to border, then curved 

inward across border to merge imperceptibly with anterior margin. Posterior section of facial suture divergent almost straight laterally behind palpebral lobe, 

then curved strongly backward to posterior margin.

Free cheek known only for type species. Border 

broad, gently convex, extending laterally into broadbased genal spine that is distinctly anterior to genal 

angles of cephalon. Lateral border furrow shallow. 

Posterior border furrow narrow, moderately deep, connected to lateral furrow at base of genal spine. Eye 

surface joined to ocular platform without intervening 

infraocular ring. Ocular platform gently convex, 

about as wide as border. Anterior sutural margin about 

parallel to posterior border furrow.

Pygidium small, subovate in outline; known only for 

type species. Axis prominent, tapered backward, 

bluntly rounded at rear; width about equal to width of 

pleural region, length slightly less than that of pygidium. Two ring furrows present posterior to articulating furrow. Pleural fields crossed by one or two 

shallow pleural furrows. Border poorly defined and 

narrow and has three or four pairs of short marginal 

spines.

External surfaces of known species partly or wholly 

covered with fine closely spaced granules.

723 - 401 O - 64 - 2
F10 CONTRIBUTIONS TO PALEONTOLOGY

Discussion. The description is based on the study of 

all the specimens of Zacanthopsis in the collections at 

the U.S. National Museum or in the U.S. Geological 

Survey. The slender anteriorly expanded glabella and 

the wide fixed cheeks having long arcuate palpebral 

lobes whose anterior ends are distinctly separated from 

the axial furrows, combined with the presence of a moderately well-defined frontal area and short posterior 

limbs distinguish species of this genus from other 

corynexochid trilobites. All known specimens of 

Zacanthopsis are from Lower Cambrian rocks. Because the associated parts of Z. lev is (Walcott), the 

type species, have never been adequately illustrated, 

they are presented here (pi. 3 figs. 1-3) for comparison 

with Z. contracts n. sp. and for future reference.

Zacanthopsis contractus n. sp. 

Plate 3, figures 4-6

Diagnosis. Species of Zacanthopsis in which the 

cranidium has anterior border convex, moderately well 

defined; width between anterior sections of facial 

sutures considerably less than width between lateral 

margins of palpebral lobes; occipital ring has short 

slender occipital spine. Axial part of glabella has fine 

closely spaced granules. Granules also apparent on 

fixed cheeks of some specimens; not observed on frontal 

area.

Discussion. This species is distinguished from 

ZacantJiopsis levis (Walcott) and from Z. virginica 

Resser by having a better defined anterior border and 

by being distinctly narrower between the anterior sections of the facial sutures than between the palpebral 

lobes. Although the species is known from only five 

cranidia, these characteristics seem constant. The 

small occipital spine, unfortunately, was broken from 

the holotype during preparation.

Genus ZACANTHOPSINA n. gen.

Type species. Zacanthopsina eperephes n. sp.

Diagnosis. Small Corynexochida that have prominent ocular ridges undifferentiated from arcuate palpebral lobes; ridges expanded slightly adjacent to 

glabella and merged with frontal glabellar lobe.

Discussion. The genus most similar to Zacanthopsina is Zacanthopsis, which also has broad fixed cheeks, 

short posterior limbs, and a short frontal area that has 

a strongly concave brim and strongly convex, elevated 

border. In Zacanthopsis, however, the ocular ridge 

reaches the glabella at the posterior part of the frontal 

lobe and does not merge with the frontal lobe.

Zacanthopsina eperephes n. sp. 

Plate 3, figures 7-9

Description. Small corynexochid trilobites; total 

length of largest individual probably less than 2 cm. 

Cranidium subquadrate in outline; sagittal length about 

two-thirds greatest width. Glabella long, slender, and 

well defined in posterior part, expanded forward and 

poorly defined anteriorly, reaching nearly to border. 

Three pairs of shallow lateral glabellar furrows apparent. Occipital furrow deep, straight. Posterior margin of occipital ring produced posteriorly into short, 

slightly upsloping median spine. Frontal area short; 

sagittal length between one-third and one-fourth sagittal length of glabella; anterolateral corners depressed. 

Brim in front of glabella strongly concave, differentiated only by change in slope from strongly convex, 

elevated border. Fixed cheeks broad, flat, nearly horizontal; width, exclusive of palpebral lobes, slightly 

greater than basal glabellar width. Palpebral lobes 

prominent, long, strongly arcuate, continuous with 

prominent ocular ridge that extends to and merges with 

anterior part of frontal lobe of glabella; line connecting 

posterior tips of palpebral lobes crosses glabella just 

anterior to occipital furrow. Lateral parts of palpebral lobes strongly curved downward and inward, so 

that sutural margin is slightly underneath dorsal part 

of palpebral lobe. Posterior limbs short, bhmt; transverse width of cranidium between tips of posterior limbs 

slightly less than cranidial width between lateral margins of palpebral lobes. Posterior border furrow deep, 

straight.

Course of anterior section of facial suture slightly 

convergent forward from palpebral lobe to inner edge 

of border, then more strongly curved across border to 

merge imperceptibly with anterior margin of cranidium. 

Course of posterior section strongly convex from palpebral lobe to posterior margin.

External surfaces of all parts of cranidium smooth.

Other parts of exoskeleton unknown.

Discussion. The inner end of the ocular ridge of 

Zacanthopsina eperephes is slightly expanded at its contact with the glabella, somewhat like that shown by 

Hupe (1953, p. 264, fig. 63A) for Kingaspis campbelli 

(King). Also, each palpebral lobe has its lateral margin turned down and slightly inward, so that the sutural 

margin is actually beneath the dorsal surface of the 

palpebral lobe, similar to the structure of the palpebral 

lobe of Pertomella yorkemis Resser (Rasetti, 1955, pi. 5, 

fig. 2). However, in Z. eperephes, the ocular ridge 

forms a continuous band, diverging only slightly posterolaterally from the anterior part of the frontal lobe 

of the glabella to the palpebral lobe. This structure 

is unique among members of the order Corynexochida.
LOWER CAMBRIAN TRILOBITE FAUNA FROM NEVADA Fll

This is a relatively rare species in the fauna and is 

represented by fewer than 10 specimens.

Order PTYCHOPABIIDA Swinnerton

Family PTYCHOPABIIDAE Matthew

Genus SYSPACEPHALTTS Kesser

Syspacephalus? sp. 

Plate 3, figures 15, 20

Discussion. Several fragmentary cranidia and a 

pygidium may represent a species of /Syspacephalus. 

The cranidia are characterized by gently convex downsloping fixed cheeks, small palpebral lobes situated 

opposite the anterior half of the glabella, and facial 

sutures that converge slightly forward. These have 

been cited by Rasetti (1955) as distinctive characteristics of Syspacephalus. However, the species illustrated here has much longer distal parts of the posterior 

limbs than does the type species, S. charops (Walcott). 

In S. charops the transverse length of the distal part 

of the posterior limb is less than half the transverse 

length of the proximal part. On the specimen illustrated here the transverse length of the distal part of 

the posterior limb is nearly equal to that of the 

proximal part. The form of the posterior limb is generally not so variable in younger ptychoparioid genera; 

for this reason, the generic assignment of the illustrated specimen is questioned. An associated pygidium having fine granular ornamentation similar to that 

of the illustrated cranidium may belong to the species. 

It is characterized by being nearly twice as wide as 

it is long, by having a low axis that tapers backward 

and merges with the posterior part of the pygidium, 

and by having four or five ring furrows and two or 

three pleural furrows. No clearly defined border is 

present. Without a larger sample, these specimens 

cannot be adequately identified.

POSITION UNCERTAIN

Pygidia of at least four species of trilobites cannot 

be assigned with certainty to the cranidia described 

herein. Their description and possible affinities are 

discussed below.

Genus and species undetermined 1 

Plate 3, figure 16

Description. Pygidium subsemicircular in outline. 

Axis long; sides subparallel; posterior end strongly 

rounded, prominent, reaching to inner edge of border. 

Four or five complete ring furrows posterior to articulating furrow. Pleural fields crossed by five broad, 

deep pleural furrows and four narrower interpleural 

furrows that terminate at inner edge of border. Border 

narrow, of nearly constant width; has two pairs of 

short prominent anterolateral border spines. External

surfaces of all parts covered with moderately coarse 

granules.

Discussion. This species, known from 10 pygidia 

ranging in sagittal length from 2 mm to 9 mm, is 

characterized particularly by well defined pleural and 

interpleural furrows and by two pairs of anterolateral 

border spines.

The species is most like Olenoides hybridus Resser 

(1938, p. 91) from the Lower Cambrian of Virginia in 

possessing twro pairs of short anterolateral spines. It 

differs from the eastern species by having the ridges adjacent to each interpleural furrow on the pleural field 

of the pygidium of nearly constant and equal width. 

In this respect, the pleural fields are more like those of 

Bonniopsis virginica Resser, which also has two border 

spines. In B. virginica, however, the border behind the 

spines is a flat flange. More must be learned about the 

other parts of the trilobite described here before it can 

be adequately understood and formally named.

Genus and species undetermined 2 

Plate 3, figure 17

Description. Small pygidia, subovate in outline; 

sagittal length about five-eights maximum width. Axis 

prominent, broad, strongly rounded at rear, nearly 

reaching to posterior margin; width slightly less than 

one-half maximum pygidial width. Two ring furrows 

posterior to articulating furrow; first furrow unusually 

deep, overshadowed by strongly convex ring of first segment. Pleural regions narrow, subtriangular; border 

not well defined. Two shallow pleural furrows, not 

reaching to margin. Margin has four pairs of short 

spines decreasing in size posteriorly. External surface 

covered with fine closely spaced granules.

Discussion. This pygidium is most like the pygidium 

of Zacanthopsls levis (Walcott) and may be the pygidium of Z. contractus n. sp. However, the possibility 

that it may be the pygidium of either Zacanthopsina 

eperephes n. sp. or Stephenaspisl avitm n. sp. cannot 

be excluded, and therefore, the generic assignment is in 

doubt.

Genus and species undetermined 3 

Plate 3, figure 18

Description. Small pygidia, subsemicircular in outline, length slightly less than one-half maximum width. 

Axis prominent, tapered backward, strongly rounded at 

end; length from articulating furrow about eight-tenths 

length of pygidium; width slightly less than one-third 

maximum pygidial width. Two complete ring furrows 

posterior to articulating furrow. Pleural regions have 

poorly defined narrow border and three shallow furrows 

and two even shallower interpleural furrows, not crossing border. Pygidial margin does not have spines. 

External surface smooth or slightly roughened.
F12 CONTRIBUTIONS TO PALEONTOLOGY

Discussion. This pygidium is most like the pygidium of Wenchemnia (Kasetti, 1951, pi. 11) in general 

morphology, but it has one less axial segment and one 

less pleural segment. Without good evidence for a correct association of a cranidium, a generic assignment is 

not possible.

Genus and species undetermined 4 

Plate 3, figure 19

Description. Small pygidia, subsemicircular in outline ; sagittal length about one-half width. Axis prominent, broad, strongly rounded at end; length about 

three-fourths length of pygidium; width slightly more 

than one-third greatest pygidial width. Two ring furrows posterior to articulating furrow. Pleural regions 

do not have well denned border. Three pleural furrows, terminated laterally just before reaching pygidial 

margin. Three pairs of short, nubby marginal spines. 

External surface covered with fine closely spaced granules barely visible even after whitening.

Discussion. This pygidium cannot be assigned with 

certainty to any of the described species in the fauna. 

If classified by relative abundance, size, and external 

ornamentation, it would seem to be the pygidium of 

Stephenaspisi. avitus n. sp. Its structure, however, is 

completely unlike that of the type species of Stephenaspis. If the association is correct, 8. ? avitus may be 

more closely related to the early Middle Cambrian 

species, PolieUa denticulata. ( See p. F9).

REFERENCES

Bell, G. K., Jr., 1931, The disputed structures of the Mesonaeidae

and their significance: Ain. Mus. Novitates, no. 475, 23 p. 

Billings, Elkanah, 1861, On some new or little known species of

Lower Silurian fossils from the Potsdam group (Primordial

zone), in Hitchcock, Edward, and others, 1861, Report on

tlie geology of Vermont, v. 2: Claremont, N.H., p. 942-960. 

Cooper, G. A., and others, 1952, Cambrian stratigraphy and

paleontology near Caborca, northwestern Sonora, Mexico:

Smithsonian Misc. Colln., v. 119, no. 1,184 p. 

Harrington, H. J., and others, 1959, Arthropoda 1, in Treatise on

invertebrate paleonthology, Part O : Lawrence, Kans., Geol.

Soc. America and Univ. Kansas Press. 560 p. 

Hupe, Pierre, 1953, Contribution a 1'etude du Cambrian inferieur et du Precambrien III de L'anti Atlas Morocain:

Serv. Geol. Moroe. Notes and Mem. 103, 402 p. 

Lake, Philip, 1937, A Monograph of the British Cambrian trilobites, pt. X: Paleontographical Soc., v. 90, p. 225-248. 

Lermontova, E. B., 1940, in Vologdin, A. G., Atlas of the leading

forms of the fossil faunas of the U.S.S.R., v. 1, Cambrian:

Moscow, VSEGEI, 193 p. 

 1951, Nizhuekenibriiskie trilobity i brakhiopody vostochnoy

Sibiri: Moscow, VSEGEI, 218 p. 

Lochman, Christina, 1947, Analysis and revision of eleven

Lower Cambrian trilobite genera : Jour. Paleontology, v. 21,

no. 1, p. 59-71. 

McLaughlin, K. P., and Enbysk, B. B., 1950, Middle Cambrian

trilobites from Pend Oreille County, Washington: Jour.

Paleontology, v. 24, no. 4, p. 466-471.

Nelson, C. A., 1962, Lower Cambrian-Precambrian succession, 

White-Inyo Mountains, California : Geol. Soc. America Bull., 

v. 73, no. 1, p. 139-144.

 1963, Stratigraphic range of Ogygopsis: Jour Paleontology, v. 37, no. 1, p. 244-248.

Palmer, A. R., 1957, Ontogenetic development of two olenellid 

trilobites: Jour. Paleontology, v. 31, no. 1, p. 105-128.

Pokrovskaya, N. V., 1959, Trilobitovaya fauna i stratigrafiya 

kembriyskikh otlozheniy Tuvy: Akad. Nauk SSSR, Geol. 

Inst. Trudy, no. 27, 199 p.

Poulsen, Christian, 1932, Lower Cambrian faunas of east Greenland : Medd. om Gronland, v. 87, no. 6, 66 p.

 1958, Contribution to the paleontology of the Lower 

Cambrian Wulff River formation: Medd. om Gronland, v. 

162, no. 2, 24 p.

1959, in Harrington, H. J., and others, 1959.

Rasetti, Franco, 1948, Lower Cambrian trilobites from the 

conglomerates of Quebec (exclusive of the Ptychopariidea) : 

Jour. Paleontology, v. 22, no. 1, p. 1-24.

 1951, Middle Cambrian stratigraphy and faunas of the 

Canadian Rocky Mountains: Smithsonian Misc. Colln., v. 

116, no. 5, p. 1-277.

 1955, Lower Cambrian ptychopariid trilobites from the 

conglomerates of Quebec: Smithsonian Misc. Colln., v. 128, 

no. 7, p. 1-35.

1959, in Harrington, H. J. and others, 1959.

Raymond, P. E., 1912, Notes on parallelism among the Asaphidae : 

Royal Soc. Canada Trans., 3d ser. v. 5, sec. 4, p. 111-120.

 1928, Two new Cambrian trilobites: Am. Jour. Sci., 5th

ser., v. 15, p. 309-313. 

Resser, C. E., 1928, Cambrian fossils from the Mohave Desert:

Smithsonian Misc. Colln., v. 81, no. 2,14 p.

 1936, Second contribution to nomenclature of Cambrian 

trilobites : Smithsonian Misc. Colln., v. 95, no. 4, 29 p.

 1937, Elkanah Billings' Lower Cambrian trilobites and 

associated species: Jour. Paleontology, v. 11, no. 1, p. 43-54.

 1938, Cambrian system (restricted) of the southern Appalachians : Geol. Soc. America Spec. Paper 15, 140 p. 

1939, The Ptarmigania strata of the northern Wasatch

Mountains: Smithsonian Misc. Colln., v. 98, no. 24, 72 p. 

Resser, C. E., and Howell, B. P., 1938, Lower Cambrian Olenellus

zone of the Appalachians: Geol. Soc. America Bull., v. 49,

no. 2, p. 195-248. 

Rominger, C. L., 1887, Description of primordial fossils from

Mt. Stephens, NW Territory of Canada: Acad. Nat. Sci.

Philadelphia Proc. for 1887, p. 12-19. 

Shaw, A. B., 1955, Paleontology of northwestern Vermont, pt.

V, The Lower Cambrian fauna: Jour. Paleontology, v. 29,

no. 5, p. 775-805. 

Shinier, H. W., and Shrock, R. R., 1944, Index Fossils of North

America: Massachusetts Institute of Technology, The Technology Press, 837 p. 

Walcott, C. D., 1886, Second contribution to the studies on the

Cambrian fauna of North America: U.S. Geological Survey

Bull. 30, 368 p.

 1889, Description of new genera and species of fossils 

from the Middle Cambrian: U.S. Natl. Mus. Proc., v. 11, 

p. 441-446.

 1910, Olenellus and other genera of the Mesonaeidae: 

Smithsonian Misc. Colln. v. 57, no. 6, p. 233-422.

 1916, Cambrian trilobites: Smithsonian Misc. Colln. v.

64, no. 5, p. 303-456.

Wanner, Atreus, 1901, A new species of Olenellus from the Lower 

Cambrian of York County, Pennsylvania : Washington Acad. 

Sci. Proc., v. 3, p. 267-272.
INDEX

avitus, Stephenaspis.

[Italic page numbers indicate descriptions]

Page 

. Fl, 2,8,11,12; pi. 3

Bathyuriscus batis ___________________________________ 7

Bathyurus parvulus __________________________________ 5

batis, Bathyuriscus ___________________________________ 7

Ogygopsis.. ........................................................... 2,7; pi. 2

Bibliography ___________________________________ 12 

bispinosa, Stephenaspis ________________________________ 8, 9 

Bonnia... ........... ___ .. ____________________________ 1,5

brennus ................................... __________________ 5

caperata . .. ... ........... ................. ....... ........ 1,2,5; pi. 2

columbensis 5

 5

 5

 11

 - . 5

Bristolia. _________________________________________ 1,2

buelnaensis, Wanneria......_____________________________ 4

(Bonnia), Corynexochus . 

Bonniopsis virginica ..... 

brennus, Bonnia. .......

campbelli, Kingaspis.......................................................... 10

caperata, Bonnia___________________._ ___________ 1,2,5; pi. 2 

Carrara Formation___ ___________________________ 1 

charops, Syspacephalus...............................................^........ 11

columbensis, Bonnia.......................................................... 5

contractus, Zacanthopsis............................................. 1,2,10,11; pi. 3

Corynexochida..__________________________________ 5 

Corynexochus (Bonnia)........................................................ 5

denticulata, Poliella. __________________________________ 9,12

Dolichometopidae:________________________________ 9

Dorypygidae . .___..___....________......__ 1,5

elongata, Ogygopsis............................................................ 7

Taxioura.................................................................. 7

eperephes, Zacanthopsina............................................ 1,2,10,11; pi. 3

Esmeraldina macer............................................................ 4

fieldensis, Bonnia.

Genera and species undetermined____.________________ 11,12; pi. 3 

Goldfieldia. ................................................................ 7

padfica--. ..................................................... 1.2,7,8; pi. 1

granulatus, Paedeumias...... _____________________.... 1,2,3,4; pi. 1

(Holmia) walcottanus, Olenettus. 

hybridus, Olenoides..............

Kingaspis campbelli. 

klotzi, Ogygia.......

Ogygopsis........

Lancastria roddyi.............................................................. 8

Levis conglomerates___ _____.___________________ 2 

levis, Olenoides................................................................ g

Zacanthopsis..................................................... . 10,11; pi. 3

macer, Esmeraldina... 

magna, Taxioura......

maladensis, Olenoides. 

Metaline Limestone..

nathorsti, Wanneria.

Ogygia klotzi.................................................................. 6

Ogygopsidae_ ___ _________________________ 1,6 

Ogygopsis........ ....... 6,7

batis................. ........................................... 2,7; pi. 2

elongata... 

klotzi..... 

spinulosa. 

typicalis...

OleaellidaeOlenettus... ...............

(Holmia) walcottanus . 

Olenoides.. ...............

hybridus .... . ..........

levis... ................

maladensis. ... . .......

spp.- -- 

Oryctocephalidae,.

padfica, Goldfieldia................................................... 1,2,7,

Paedeumias.......................................____ ._______ 

granulatus.-....--.....-................ _ 1, 2, 3,

transitans............ ......... _._

parvulus, Bathyurus__---_ 

Periometta yorkenm....._________--- __-__ .-. 

Poliella denticulata_________-_.__-_____-__ - 

Ptarmigania.. .........-- -- 

Ptarmiganoides.------...... -. --- -- - ...

Ptychopariida - 

Ptychopariidae.-._...--_____- -

Page

Fl,2

2,3

3

2,5,6 

. 11 

. 9 

. 6 

B; pi. 2 

1,2,7

2

5

10

9,12

11

1,11

Redlichiida . 

rnddyi, Lancastria.

Saline Valley Formation_ 1,2 

spinulosa, Ogygopsis.---------............. ....-_ 7

Stephenaspis .............................................................. 8,9,12

asitv* . - ---- -- 1,2,8,11,12; pi.3

bispinosa________ -- - - 8,9 

Syspacephalus --- ---- 11

charops--------......_ -- --- 11

sp............... . -- .--------------------------_--- 2, 11; pi. 3

Taxioura........ -

elongata............

magna.............

typicalis............

Tonkinella valida... __ 

transUans, Paedeumias. 

typicalis, Ogygopsis.....

Taxioura.......-...

valida, Tonkinella .... ___ - -- - - --- 8

virginica, Bonniopsis... ..... .. ........... ................... - 11

Zacanthopsis.. ..... ... ..--- -- - -- --- 10

walcottana, Wanneria.-.. . - 2, 4; pi. 1 

walcottanus, Olenettus (Holmia').- - 3

Wanneria .... . - - - ^>*

buelnaensis... - -- - 4 

nathorsti.--.-- ----- - *

walcottana. ........... -- --- - --- - - ----- - ----- 2, k P1 - 1

Wenchemnia.-. - 12

yorkensis, Periometta .

Zabriskie Quartzite_ --- ----- - 

Zacanthoides.-..........- - --

Zacanthoididae -~--- - 

Zacanthopsina... 

eperephes..----------- - - 1, 2, , U

Zacanthopsis- - - - 1

contractus... --- ------ 1,2, 10, 11

levis.....-----.-...----...---.---------------.-.-.--......-...-----. 10,11;

virginica..-. ... .........-.--.-. - - -- 

F13

i

9 

1,8

10

;pl. 3 

,0,10 

;pl.3 

pi. 3

10

PLATES 1-3
Plate 1

FIGURES 1-10. Paedeumias granulatus n. sp. (p. F3).

1. Left side of cephalon, X 4, USNM 144250.

2. Latex cast of central part of cephalon, X 5, USNM 144251.

3. Holotype cephalon, X 3, USNM 144252.

4. Anterior part of cephalon showing granular ornamentation of frontal lobe, X 10, USNM 144253.

5. 7. Meraspid cephala, X 10, USNM 144254, 144255.

6. Central part of cephalon showing granular ornamentatior, X 8, USNM 144256.

8. 10. Fragments of large cephala showing pit in posterior part of frontal lobe and variation in ornamentation, 

X 3, X 6, USNM 144257, 144258.

9. Hypostome, X 4, USNM 144259. 

11-13, 15. Wanneria cf. W. walcottana (Wanner) (p. F4).

11. Detail of ventral surface of a thoracic segment showing perforations outlining margins of polygons, X 15, 

USNM 144260.

32. Small cephalon showing ornamentation, X 3, USNM 144261.

13. Small cephalon, X 2, USNM 144262.

15. Hypostome showing typical ornamentation of Wanneria, X 2, USNM 144263. 

14, 16-18. Goldfieldia pacifica n. gen., n. sp. (p. F7).

14. Stereogram of holotype cranidium, X 8, USNM 144264.

16. Cranidium, X 10, USNM 144265, USGS colln. 3659-CO.

17. Cranidium, X 8, USNM 144266.

18. Cranidium, X 10, USNM 144267.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 483-F PLATE 1

18

OLENELLIDAE, ORYCTOCEPHALIDAE
PLATE 2

FIGURES 1-6. Ogygopsis batis (Walcott) (p. F7).

1. Free cheek, X 3, USNM 144268.

2. Stereogram of typical cranidium, X 3, USNM 144269.

3. Pygidium, X 2, USNM 144270.

4. 5. Pygidia showing variation in ornamentation, and nature of anterolateral spine, X 5, USNM 144271, 144272.

6. Cranidium showing typical ornamentation, X 5, USNM 144273. 

7-10. Olen&ides spp. (p. F5).

7. Cracidium, X 4, USNM 144274.

8. Short-spined pygidium, X 3, USNM 144275, USGS colln. 3655-CO.

9. 10. Long-spined pygidia, X 4, and X 2 respectively, USNM 144276, 144277. 

11-16. Bonnia caperata K. sp. (p. F5).

11. Stereogram of cranidium, X 3, USNM 144278.

12. Free cheek, X 3, USNM 144279.

13. Cranidium showing subdued ornamentation on fixed cheeks, X 3, USNM 144280.

14. 15. Pygidia showing variation in degree of development of ornamentation and of veins on pleural segments.

X 3, USNM 144281, 144282. 

16. Stereogram of holotype pygidium, X 3, USNM 144283.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 483-F PLATE 2

15 16 

OGYGOPSIDAE, DORYPYGIDAE
PLATE 3

FIGURES 1-3. Zacanthopsis levis (Walcott) (p. FlO).

1. Stereogram of cephalon, X 8, USNM 144284.

2. Free cheek, X 8, USNM 144285.

3. Pygidium, X 8, USNM 144286. 

All from USGS colln. 1392-CO, Pioche, Nev. 

4-6. Zacanthopsis contractus n. sp. (p. FlO).

4. Stereogram of holotype cranidium, X 8, USNM 144287.

5. 6. Cranidia, X 5, USNM 144288, 144289. 

7-9. Zacanthopsina eperephes n. gen., n. sp. (p. FlO).

7. Stereogram of holotype cranidium, X 5, USNM 144290.

8. Holotype cranidium, right side view showing course of facial suture, X 5.

9. Latex cast of cranidium, X 5, USNM 144291. 

10-14. Stephanaspist avitus n. sp. (p. F8).

10. Stereogram of incomplete cephalon, X 5, USNM 144292.

11. 12. Cranidia, X 4, USNM 144293, 144294.

13. Free cheek, X 5, USNM 144295.

14. Stereogram of holotype cranidium, X 4, USNM 144296. 

15, 20. Syspacephalusf sp. (p. Fll).

15. Cranidium, X 10, USNM 144297. 

20. Pygidium, X 10, USNM 144298.

16. Genus and species undetermined 1 (p. Fll). 

Pygidium, X 3, USNM 144299.

17. Genus and species undetermined 2 (p. Fll). 

Pygidium, X 10, USNM 144300.

18. Genus and species undetermined 3 (p. Fll). 

Pygidium, X 6, USNM 144301.

19. Genus and species undetermined 4 (p. F12). 

Pygidium, X 5, USNM 144302.

O
GEOLOGICAL SURVEY PROFESSIONAL PAPER 483-F PLATE 3

17 18 

ZACANTHOIDIDAE, PTYCHOPARIIDAE, POSITION UNCERTAIN