Salterella from the 

Lower Cambrian of 

Central Nevada

GEOLOGICAL SURVEY PROFESSIONAL PAPER 643-H
Salteretta from the 

Lower Cambrian of 

Central Nevada

By ELLIS L. YOCHELSON, J. W. PIERCE, and MICHAEL E. TAYLOR

CONTRIBUTIONS TO PALEONTOLOGY

GEOLOGICAL SURVEY PROFESSIONAL PAPER 643-H

Description and illustration 

of an unusual fossil having 

laminated inner deposits 

containing heavy minerals

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1970
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 55 cents (paper cover)
CONTENTS

Abstract._ _-___--__---_-__-___--____-__-__ 

Introduction ______________________________

Occurrence. _______ ________________________

Other Great Basin occurrences and correlation. 

Volborthella in North America-___-_-_-____-_

Page

HI

1

1

1

Composition of Toquima Range thin sections. 

Variation in the Toquima Range Salterella--- 

Possible origin of laminae-_________________

Discussion ________________________________

References._________________-___-__---__-

Page 

H2

4

5

6

ILLUSTRATIONS

PLATE 1. Salterella and Volborthella.

2-5. Salterella from Nye County, Nevada.

[Plates follow references]

TABLES

Page 

TABLE 1. Mineralogy of discrete grains in the laminae and in the rock matrix surrounding specimens _-__________________ H3

2. Average size, in microns, of discrete detrital mineral grains in the laminae and in the rock matrix surrounding

specimens __--___________ ____________________________________________________________-_____-____ 3

CONTRIBUTIONS TO PALEONTOLOGY

SALTERELLA FROM THE LOWER CAMBRIAN 

OF CENTRAL NEVADA

By ELLIS L. YOCHELSON, J. W. PiEECE,1 and MICHAEL E. TAYLOE

ABSTRACT

Specimens of Salterella Billings, 1861, in a probable thrust 

plate in the southern part of the Toquima Range of central 

Nevada indicate the presence of Lower Cambrian rocks. These 

rocks may be correlative with part of the Harkless Formation 

in southwestern Nevada and adjacent California, although details of the range of Salterella species remain unknown.

Many of the better preserved Toquima Range specimens have 

interior laminations around a central tube. The laminae are 

composed of discrete grains of clastic origin in a brown matrix 

of calcite and (or) microcrystalline quartz replacing calcite. 

Grains within the laminae are smaller than the average size of 

grains in the surrounding rock. The size difference, as well as 

enrichment in accessory heavy minerals, suggests a deliberate 

size selectivity.

Continuous variation exists between specimens in which most 

laminae are primarily quartz grains and those in which many 

of the laminae are composed of dark minerals. Specimens having laminae formed mainly of dark-colored grains resemble 

Volborthella Schmidt, 1888. Volborthella may be similar to Salterella except that in Volborthella the outer shell is not 

preserved.

INTRODUCTION

Salterella was collected by F. G. Poole of the U.S. 

Geological Survey in 1967 from rocks in a probable 

thrust plate in the Toquima Kange, Nye County, Nev. 

In the absence of more characteristic fossils, this occurrence of Salterella is of value in confirming the presence 

of Lower Cambrian rocks. Furthermore, the newly discovered material provides additional data 011 composition of hard parts. The biological placement of the 

genus a vexing problem since the original generic 

description by Billings in 1861 continues to be a 

problem and, if anything, the new specimens complicate it.

Tliis study of Salterella would have been impossible 

without the specimens collected by F. G. Poole. It was 

aided materially by thin sections prepared by William 

Pinckney and by photomicrographs taken by David 

Massie, both of the U.S. Geological Survey. Eugene 

Jarosewich, U.S. National Museum, determined the

1 Department of Paleobiology, U.S. National Museum, Washington,

presence of iron-bearing mineral grains within specimens by use of an electron probe.

OCCURRENCE

The specimens illustrated were obtained at USGS 

locality 6267-CO, from the west-central part of fee. 8 

(unsurveyed), T. 7 N., R. 43 E., in the Willow Spring 

area of the southern Toquima Range, Nye County, Nev. 

A few other specimens were obtained at locality 6266- 

CO in the SW1^ sec. 8, T. 7 N., R. 43 E. In addition to 

the specimens of Salterella described below, a few scraps 

of olenellid trilobites occur at locality 6267-CO, and 

"Hyolithes" occurs at locality 6266-CO.

Because Salterella can be easily recognized with a 

hand lens, it holds considerable promise as a field guide 

for dating and mapping. It is hoped that this paper 

will lead to collection of Salterella from other localities 

in the Great Basin.

OTHER GREAT BASIN OCCURRENCES AND 

CORRELATION

Salterella has been collected previously from southwestern Nevada, but the details of its occurrence are 

somewhat vague, and no attempt has been mac'e to 

describe or differentiate species in stratigraphic sequence. The genus apparently was first noted by O. D. 

Walcott in a collection he made in 1896, labeled "Summit on road, Silver Peak to Fish Lake Valley." In 1899, 

F. B. Weeks, attached to H. W. Turner's field pTty, 

collected other specimens from a number of localities 

within the Silver Peak quadrangle; Turner (1909) 

mentioned the occurrence of Salterella only in general 

terms in the greenish slates and limestones of Early 

Cambrian age. Walcott (1908, p. 189) reported Salterella at two horizons within his Barrel Spring, T Tev., 

section, but in his later work on Cambrian brachio^ods 

(Walcott, 1912, p. 138), he noted only a single occurrence, probably because one of the beds may not have 

yielded associated brachiopods.

Hi
H2 CONTRIBUTIONS TO PALEONTOLOGY

Salterella was collected from the Harkless Formation (Nelson, 1962) in Nevada during 1960 by J. Wyatt 

Durham and E. H. McKee of the University of California, Berkeley. Their material is from the same general 

area in Esmeralda County, Nev., where Walcott and 

Weeks collected. Specimens were obtained in the Magruder Mountain quadrangle, about one-fifth mile south 

of the "Palmetto Wash" road along the top of a flat hill 

in the NW^NW^ sec. 13, T. 6 S., R. 39 E. (Univ. of 

California, Berkeley, Mus. Paleontology loc. B-4035). 

In addition to Salterella, the trilobite Bonnia sp. is also 

in the Berkeley collection.

A representative specimen from the Harkless Formation is shown on plate 1, figure 1. Representatives of 

Walcott's material are illustrated on plate 1, figure 3; 

probably his specimens are also from the Harkless 

Formation. This Esmeralda County material is not well 

preserved, but because of its general similiarity to that 

collected by Poole, correlation of the southern Toquima 

Range SaltereJla-be&ring beds with the Harkless is suggested.

Additional collections from both areas may eventually 

make possible more refined correlations within the 

Harkless and equivalent rock units; fossil material and 

relevant stratigraphic information for such study are 

not currently available. Only recently has it been noted 

that not only does Salterella have considerable stratigraphic utility as a guide to Early Cambrian age, but 

details of the range of species may be useful for local 

zonation and correlation (Yochelson and others, 1968).

Even without more detailed data, the occurrence of 

/Salterella is significant. The genus is confined to rocks 

of Early Cambrian age. Salterella in the fine-grained 

clastic strata of central Nevada corroborates Poole's 

initial Lower Cambrian rock assignment (F. G. Poole, 

written commun., 1967) based on lithological similarity 

to known Lower Cambrian strata in other parts of the 

southern Great Basin.

VOLBORTHELLA IN NORTH AMERICA

Lipps and Sylvester (1968) recently reported the occurrence of VolbortheHa Schmidt, 1888, in the lower 

part of the Harkless Formation in the Inyo Mountains 

of southern California. It had not previously been reported from North America, and these authors deserve 

full credit for identifying this enigmatic fossil from 

poorly preserved specimens.

Lipps and Sylvester (1968, p. 331) reported zircon, 

magnetite, pyrite, and tourmaline in their specimens. 

Examination of their thin sections indicates that their 

material is at least similar to the Nevada specimens described in "Composition of Toquima Rang« thin sections"; their specimens are very incomplete when 

compared with the Nevada specimens. The Inyo Mountains material they studied is from a somewhat metamorphosed matrix. It may be that less resistant minerals 

or an organic cement holding some grains in place was 

destroyed during metamorphism.

Volbortliella is well known in the Cambrian of 

Europe, especially the Baltic region (Schindewolf, 

1934; Prantl, 1948). Topotypical representatives of the 

genus are illustrated here on plate 1, figures 2, 4, and 5.

Yochelson and Taylor in unpublished investigations 

during 1966 concluded that V' olborthella- specimens are, 

in fact, poorly preserved; some of the apparent morphological features, especially the absence of an outer 

shell, are the result of diagenetic alteration of the fossils. This opinion was based on compariscn of wellpreserved specimens of Salterella from Pennsylvania 

(Yochelson and others, 1968) with topotype specimens 

of Volborthella. However, before the receipt of Poole's 

collections, it had not been possible to document fully 

the similarity of /Saltere7la-like forms to Volborthellalike organisms.

COMPOSITION OF TOQUIMA RANGE THIN 

SECTIONS

The Toquima Range specimens of Salterella. occur in 

a very fine grained sandstone composed primarily of 

subangular to rounded quartz. Most of the quartz grains 

in the rock are clear, although some have T^hat is apparently an iron stain. Most of the stained grains are 

near Salterella individuals, and staining is rare away 

from the specimens.

The quartz grains are mainly in contact with adjacent 

grains although there is a small amount of infilling by 

siibmicroscopic particles, presumably clay. A few thin 

sections have areas where clay-sized particles dominate 

and where the quartz grains float in an argillaceous 

matrix.

Calcite and microcrystalline quartz are also present. 

Microcrystalline quartz (chert) is generally the second 

most abundant mineral in the rock. Calcite is rare, 

except in two thin sections where it is the predominant 

mineral (pi. 5, figs. 1,6).

Heavy minerals are rare in the matrix in which the 

specimens of Salterella are found, but a variety of them 

are concentrated in some specimens. Threo examples 

rich in heavy minerals are indicated in ta.ble 1. The 

heavy-mineral grains in the rock matrix are coarse silt 

size or smaller, as noted in table 2, and Iiav3 a smaller 

average size within the fossils.
8ALTERELLA FROM THE LOWER CAMBRIAN OF CENTRAL NEVADA H3

TABLE 1. Mineralogy of discrete grains in the laminae and in the 

rock matrix surrounding specimens

PI. 4, fig. 5 PL 5, fig. 3 2 PI. 5, fig. 4

Laminae Matrix Laminae Matrix Laminae Matrix

Sillimanite. -----------

Rutile - ---

Opaque (primarily

Other... -- __.--_-.

31 57 16 76 

59 6 19 

- __.-. _._ 1 --. .- .

---------------- 3 .-_.__.._

42 

K

21

3 __---_--_---_...---__

o

-----._.-.._-.-....--_---.--- 1 ...

1 ----. -_.-.--.-_.-__----.-..

1 ......... 6 _. -.-

1 .._....__ 3 .............

8 2 61 3

30 

14

4 ...

1 ...

3 ...

4 ...

4 ...

37

1 ...

68 

16

1 

15

Total grains 

counted... 70 100 100 100 100

1 Dark-colored minerals within the matrix filling the apertural cavity include 

staurolite, tourmaline, hypersthene, and sphene.

2 The matrix filling the aperture contains approximately 50 percent chert and 50 

percent calcite.

TABLE 2. Average size, in microns, of discrete detrital mineral 

grains in the laminae and in the rock matrix surrounding 

specimens

Rock..-..-.-.

PI. 2,

fig. 1,

and

PI. 3,

fig. 1

58

171

PI. 2,

fig. 2,

and

PI. 3,

fig. 2

53

88

PI. 2,

fig. 3

149

PI. 2,

fig. 5

61

100

PI. 2,

fig. 4

49

89

PI. 4,

fig. 3

66

106

PI. 5

fig. 2

64

105

The specimens of Scdteretta, show four distinct areas 

(for example, pi. 3, fig. 1). The first, the shell wall, is 

composed of calcite or microcrystalline quartz replacing 

calcite. The second is the part just posterior of the aperture and is termed here the apertural cavity. This is 

usually filled with clastic material similar in size and 

composition to that of the surrounding rock. There is 

no evidence of lamination or sorting of the material 

within this apertural cavity. The third area, extending 

from the apertural cavity to the apex, is a central tube, 

which is now filled with sparry calcite.

Finally, a series of laminae, which extend from the 

central tube to the outer wall, is present in nearly all 

specimens of Salterella. There is considerable variation 

in the appearance of the laminae. In some instances, 

the laminae are composed of alternating layers of dark 

material and mineral grains (pi. 2, figs. 1, 2, 4, 5; pi. 3; 

pi. 4, figs. 5, 6; pi. 5, figs. 4, 5). In other specimens, the 

laminae can be differentiated only by the color density 

of the material and by the inclusion of a few lighter 

colored detrital mineral grains within the laminae (pi. 

2, fig. 3; pi. 4, figs. 2, 4; pi. 5, figs. 2, 3). Between the 

outer shell wall and the laminae of detritus is an irregular thin layer of calcite or microcrystalline quartz,

shown in most photographs, but especially prominent 

on the left side of plate 3, figure 1. Detailed microscopic 

examination indicates that this apparent layer is actually formed by extension of the laminae up along the inner surface of the shell wall.

In most instances, the nongranular dark material in 

the photographs is either calcite or microcrystalline 

quartz, presumably replacing the calcite. Calcite and 

(or) microcrystalline quartz appears to be the cementing material holding the detrital grains in place.

In a few specimens no laminae are present (pi. 5, 

fig. 1) or the laminae are poorly preserved (pi. 5, 

fig. 6). Many of the individual lamina are broken or 

bent. Material filling the shell is similar to that of the 

surrounding rock. No indication of a central t/ube is 

present in these specimens. This absence suggests that 

inner lamination was lost after death, and the hollow 

shell was then filled by the detrital matrix.

The discrete grains within the laminae of the Sctfterella specimens are predominantly clear quartz. It appeared upon examination that the grain size within the 

laminae was smaller than that of the surrounding rock 

and that heavy minerals were concentrated within the 

laminae. To check on the concentration, point-count determinations were made on three specimens particularly 

rich in heavy minerals and on the surrounding rock 

matrix (table 1).

Quartz makes up 16 to 44 percent of the discrete 

grains within the laminae of all specimens courted, 

whereas 68 to 81 percent of the discrete grains in the 

rock matrix of the same thin sections are quartz. In all 

instances, quartz is at least 1.8 times as abundant in the 

rock as in the laminated part of the SaltereTLa specimens. Chert is the second most abundant mineral in 

the rock matrix. The rest of the discrete grains are 

heavy minerals.

The longer axes of discrete grains were measurei in 

seven specimens in which definitive laminae were p^esent and in the rock surrounding each of the specimens 

(table 2). In all instances, the average length of the 

grain axes in the laminae was less than that of the 

grains forming the rock. The range in size in the rock 

was greater than within the laminae, inasmuch as some 

of the grains within the rock were of the same size 

range as those within the laminae. No grains within 

the laminae were as large as the average for the rock, 

except where infilling might have been possible, euch 

as near the juncture of the apertural cavity and the 

upper laminae.

There appears to be an apparent selectivity by the 

organism based on grain size, the smaller grains being 

preferentially enriched within the laminae. The concentration of heavy minerals within the laminae, at l°,ast
H4 CONTRIBUTIONS TO PALEONTOLOGY

in the three specimens on which point counts were made, 

is attributed to the prevalence of heavy minerals in the 

smaller grain sizes because of hydraulic equivalence.

One thin section was subjected to elemental analysis 

for silicon, magnesium, and iron by use of an ARL 

microprobe. Selected fields of laminae were subjected 

to 20 kilovolts and 0.15 microamperes. Spots of 

1-micron diameter were counted for 10 seconds.

Of the three elements determined, two opaque areas 

were found to contain only iron. The fact that both 

areas are bounded by lines meeting at right angles, suggests a possible cubic crystal habit. For these reasons, 

we believe that some of the opaque material, especially 

that not in discrete grains, is iron oxide replacing 

pyrite.

Clear grains show the presence only of silicon. Many 

of the dark grains show both silicon and iron. Microscopic examination suggests that this is microcrystalline 

quartz replacing calcite. None of the elements tested for 

would be definitive for calcite, except for calcite containing magnesium.

VARIATION IN THE TOQUIMA RANGE 

SALTERELLA

The SaltereU-a, specimens show considerable individual variation. The differences among specimens are so 

great that some features are judged to be partly secondary and inorganic in origin. Accordingly, it is appropriate to consider the more striking of these differences.

So far as can be determined, the external shape is a 

simple high cone closed at the apical end (pi. 3, figs. 

1, 2). The wall tapers gradually along the outer onethird of the apertural cavity but is otherwise nearly 

constant in thickness from the shell apex to the aperture (pi. 4, fig. 5). The apertural cavity is deep, constituting approximately one-third of the total length of 

the larger shells. A central tube extends from the cavity 

to near the apex (pi. 3, fig. 1; pi. 4, fig. 1). Except for 

this tube, the interior of the cone is filled with laminae 

composed either of discrete grains in a microcrystalline 

matrix or of a microcrystalline material with no discrete grains. The floor of the apertural cavity is formed 

by the last lamina. Great variation is seen in the appearance of the laminae, but discussion of this feature is 

given last.

In the best preserved specimens, the wall is composed 

of microcrystalline calcite that has been replaced to 

some extent by microcrystalline quartz. In other specimens, the wall is composed of microcrystalline quartz 

with only a small amount of calcite remaining as remnants. In at least one specimen, part of the outer wall 

has been removed from the upper part of the shell, a

condition leaving a series of laminae formed of siltsized grains in a dark matrix (pi. 5, fig. 2).

The apical part of some tubes is broken. Incomplete 

specimens may range from those having an irregular 

break (pi. 5, fig. 2) through those in which the apical 

area is separated a short distance (pi. 5, fig. 1) to those 

in which there is definitely no indication of an apex 

(pi. 5, fig. 4). The tubes that contain silt grains in 

laminated arrangement apparently do not lose orientation of these grains during the breaking off of the apex 

(pi. 5, fig. 2). This further supports the assumption 

that the silt grains within the laminae were held together by some matrix.

Laminae are absent, wholly or in part, f^om broken 

and distorted shells (pi. 5, figs. 1, 4), and from >at least 

one undistorted shell (pi. 5, fig. 6). The only specimens 

examined in which no laminae, or hint of such, are 

present are from limestone composed primarily of 

sparry calcite. The atypical nature of the matrix suggests that these specimens may have been transported 

farther than those in the quartz sandstone and 

that the matrix of the laminae disintegrated during 

transportation.

There are differences in the depth of the apertural 

cavity among specimens. Some of this variation in 

depth may be related to ontogenetic change. However, 

in a few specimens the outer rim of the aperture has 

been broken back (pi. 2, figs. 3, 5). In still others there 

is a suggestion that the laminae close to th«, apertural 

cavity are missing (pi. 5, fig. 4). Difficulty in alining a 

thin section precisely through the center of a specimen 

may account for the apparent presence or absence of a 

central tube, but the iionlaminated specimens show no 

indication of this tube.

There is also variation in the external shell shape. 

Many specimens are straight, but some tubes are curved 

in thin section (pi. 5, fig. 3). Curved species presumed 

to be Salterella have been described, fc~ example, 

S. acervulosa Resser and Howell; this curvature may bethe result of tectonic activity. At least a few of the 

specimens in the Toquima Range collection are irregular enough to suggest that curvature may be due to distortion of the containing rock. The shells that contain 

mainly silt grains having no clear indicatior of internal 

lamination are frequently the ones that show the clearest 

suggestion of deformation. In at least om specimen, 

the apical area appears to be distorted into a slightly 

bulbous shape from its original pointed condition 

(pi. 5, fig. 6).

Laminae generally are broadly and si Slowly Vshaped on either side of the axial tube (pi. 2, figs. 1,2). 

They are closely spaced and are separated by a few 

irregularly spaced dark-colored layers. Clear angular
SALTERELLA FROM THE LOWER CAMBRIAN OF CENTRAL NEVADA H5

silt-sized quartz grains are the principal constituent of 

some laminae. Quartz grains may either occupy a layer 

completely, following the orientation of the laminae 

above and below it, or they may be irregularly placed 

along a predominantly dark-colored lamina (pi. 2, fig. 

5). In some individuals, laminae composed primarily of 

silt-sized quartz grains may be concentrated at the lower 

part of the shell (pi. 5, fig. 5) and slightly coarser grains 

concentrated at the upper part. In others, silt-sized 

grains of quartz are layered mainly in the upper part 

of the shell (pi. 4, fig. 5). In still other shells, very rare, 

fine-sand-sized grains are scattered irregularly through 

the silt-sized grains of the laminae (pi. 4, fig. 4).

The laminae are asymptotic to the outer wall of the 

shell. Generally, the matrix of the laminae appears to 

extend some distance up the inside of the wall, so that 

the thin section, in transmitted light, gives the appearance of a multilayered wall (pi. 3, fig. 2).

The angle that the laminae make with the central 

tube is more variable than the asymptotic curvature of 

the outer edges of the laminae. In most instances, the 

laminae meet the central tube at angles ranging from 

35° to 52°. The smaller angle is generally in the lower 

part of the shell. However, in two specimens, the laminae 

flatten out after leaving the outer wall, and in the inner 

part of the thin section, their approach to the central 

tube at nearly right angles (pi. 2, fig. 3; pi. 4, figs. 2, 4) 

makes a U rather than a V in cross section.

POSSIBLE ORIGIN OF LAMINAE

Siliceous spicules and plates are known in some living 

organisms, but animal secretion of quartz and heavymineral grains is so alien that it may be safely surmised 

that no direct physiological effect is involved in production of the laminae. Two possible explanations exist for 

the presence of such detrital particles as parts of laminae 

within the shells. First, they were iinplaced during the 

life span of the animal. Secondly, they are the result of 

post-mortem replacement by nonorganic processes.

The concept of post-mortem replacement of grains of 

selected sizes and composition which are otherwise quite 

rare in the surrounding rock requires such a complex set 

of sedimentologic circumstances as to appear nearly impossible. We therefore conclude that the laminae are 

biologically unplaced.

Lipps and Sylvester (1968, p. 329) concluded that 

Volborthella had an agglutinated test and "* * * was 

most likely a worm-like animal * * *." In a hypothesis 

that some sort of life process was involved in formation 

of laminae, the term "agglutinization" may not be fully 

appropriate, for it is generally used with reference to 

an external shell or test.

The Toquima Range specimens demonstrate quite 

clearly that the grain part of the organism is an internal structure surrounded by a conical shell, not an external test or tube. Most specimens show a central hollow tube of uniform diameter. The edges of the laminae 

maintain a nearly constant relationship to the outer T^all 

and a predictable variation to the central tube (pi. 2, 

fig. 5; pi. 3, fig. 1). This uniformity suggests that the 

tube was filled by organic material during life, the 

laminae being deposited around it and inside the outer 

wall. The grains of each lamina appear to be in a matrix 

of calcium carbonate, although in some specimens it is 

now replaced by microcrystalline quartz.

There are at least three methods by which detrftal 

grains could be implaced behind the soft parts of the 

animal to fill the earlier part of the shell. First, many 

different sorts of animals elongate their soft parts during feeding. This elongation process might have 

slightly attenuated the soft parts, a condition resulting 

in a narrow circumferential gap between the rim of the 

aperture and the main soft body mass. Grains limitei to 

a small size could filter in through this gap. Once in the 

lower part of the apertural cavity, the grains could be 

redistributed by movement of the main body mass into 

a layer one grain thick. Secretion of cement would then 

hold them in place.

The second method would be similar to the first but 

would presuppose limited movement along the bottom. 

During feeding, the animal would drag the shell along 

the bottom. Extension of the soft parts again would 

provide attenuation. That part of the shell in contact 

with the bottom would act as a scoop, and grains ec ual 

to or smaller than a given size would enter into the 

apertural cavity. Redistribution and secretion of cement would then occur.

The above two methods presuppose that no material 

finer than silt-sized grains occurs in the environment, 

inasmuch as clay-sized particles would infilter along 

with the silt grains. Very little material smaller than 

silt size occurs in the Salterella specimens examir?xi, 

although it is present but rare in the Toquima Range 

matrix rock. However, if VolbortheUa from Estonia is 

a similar animal, it would hardly seem likely that the 

clay of the surrounding rock in which Volborthella occurs (pi. 1, fig. 5) could be excluded by either of the 

above processes.

The third and probably the most logical explanation 

is purposeful selection by the organism, discrimination 

being based on grain size only. The processes by which 

the organism might select and emplace the grains is not 

known, although some sort of tentacular apparatus 

would be required to pick up a grain and move it to the 

edge of the aperture.
H6 CONTRIBUTIONS TO PALEONTOLOGY

The variation between laminae, whether primarily 

grains having a small amount of cement or primarily 

calcium carbonate having few grains, can best 

be explained by one of two methods or perhaps a 

combination of them:

1. When grains of the preferred size were plentiful in 

the immediate area of the organism, laminae of 

grains, cemented by calcite, were formed. After the 

supply was depleted and before replenishment by 

currents or before it could move into an area having 

a sufficient number of grains, the organism was forced 

to secrete calcite to maintain the proper size apertural 

cavity consistent with body size.

2. Alternatively, secretion of sufficient calcite to form 

whole laminae may have been possible for this organism only when the water was saturated. At times 

of undersaturation, grains were selected on the basis 

of size to make up for the deficiency of the mechanism.

As yet, insufficient data are available to determine 

which of the above mechanisms was dominant. For example, in contrast to the Toquima Range material, some 

Salterella from Pennsylvania occur in limestone. In that 

area, there may have been no detrital grains available, 

or the water may have been saturated enough of the time 

with calcium carbonate to permit the carbonate-secreting mechanism to function so as to permit formation of 

laminae at a satisfactory rate without the need for selection of foreign mineral grains.

DISCUSSION

The most interesting biological feature of this material is the admixture of a calcium carbonate outer 

shell and the quartz-rich or dark-mineral-rich inner 

laminae. In contrast, well-preserved specimens of Salterella of similar size and external shape from limestones 

in the eastern United States contain calcium carbonate 

in the interior and show no detrital grains of quartz or 

heavy-mineral grains.

The alternating areas of light and dark bands are 

difficult to count, but about 100 laminae occur in the 

larger specimens. The age and growth rate of these fossils are unknown. A life span of less than a year is at 

least within the order of magnitude for age of growth 

of recent calcium carbonate-secreting animals in the 

same general size range. Accordingly, each laminae 

could be the result of a body extension coupled with a 

diurnal feeding cycle.

The question of destruction versus preservation of 

laminae may be dependent upon time and distance of 

transport between death and burial. Exposure on the 

sea bottom would tend to cause a breakdown of the

cement or matrix of the laminae by solution. Movement 

of the shell would hasten loss of laminae if specimens 

were poorly cemented.

The bulbous tip on one specimen (pi. 5, fig. 6) and 

the varying diameter of other tubes are similar to features characteristic of fossils assigned to the enigmatic 

Wyattia Taylor (1966) described from upper Precambrian rocks in eastern California (see Cloud and Nelson, 1966, for differing opinions on age assignment). 

Though evidence does not warrant placing Volborthella 

and Wyattia in synonymy with /Salterella at this time, 

the preservation of the Toquima material does suggest 

that both of these generic names should be applied with 

caution to specimens not from the type areas because of 

the possible influence of diagenetic features on the 

fossils.

Destruction of the outer shell wall can be by abrasion 

before burial or by solution of the calcite after burial. 

In the Estonian specimens of Volbortkella cnly the outer shell is missing, and the edges of the laminae are 

truncated along a rather straight line (pi. 1, figs. 2, 4, 

and 5). This would indicate solution of the outer wall 

rather than abrasion, which would tend to create a 

rougher outline.

It is obvious from the Toquima Range specimens that 

some Salterella may be highly variable. Variation in 

laminae composition has been noted; this may be partly 

controlled by the environment in which the animal 

lived. Variation during ontogeny may be observed in 

the shape of the inner laminae, those in the juvenile part 

of the shell being more strongly inclined tl an those in 

the upper part of the tube.

Finally, there is the problem of the limit? of individual variation. Most specimens in the Toquima Range 

collection have V-shaped inner laminae, ^wo (pi. 4, 

fig. 4; pi. 5, fig. 2) having broadly U-shaped inner laminae may represent another species, but this is uncertain.

The obvious distinction in shape between the laminae 

of the Estonian V olbortJiella and Nevada specimens of 

Salterella, show that forms can be distinguished, though 

the level of significance to be assigned to such differences remains unknown. With the large number of variables available in Salterella, it seems advisable to delay 

any f ormal species description until additional material 

from other localities has been examined.

REFERENCES

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

Lower Silurian fossils from the Potsdam Group (Primordial 

zone), in Hitchcock, Edward, Hitchcock, Edward, Jr., 

Hager, A. D., and Hitchcock, C. H., Report on the geology 

of Vermont; descriptive, theoretical, economical, and scenographical: Claremont, N.H., v. 2, p. 942-955. [This material 

was reproduced in Palaeozoic Fossils, volume 1: Canada 

GeoT Survey, 1865, p. 1-18.]
SALTERELLA FROM THE LOWER CAMBRIAN OF CENTRAL NEVADA H7

Cloud, P. E., Jr., and Nelson, C. A., 1966, Phanerozoie-Cryptozoic and related transitions new evidence: Science, v. 154,

no. 3750, p. 766-770. 

Lipps, J. G., and Sylvester, A. G., 1968, The enigmatic Cambrian

fossil Volborthella and its occurrence in California: Jour.

Paleontology, v. 42, no. 2, p. 329-336, pi. 43. 

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

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

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

Prantl, Ferdinand, 1948, On the occurrence of the genus Volbortliella Schmidt in Bohemia (Nautiloidea) : Praha, Narodni

Mus., Sbornik, v. 4B, no. 5, Geologia et Paleontologia, no. 3,

13 p., 1 pi. 

Schindewolf, O. H., 1934, Ban und systematische Stellung der

Gattung Volborthella Schm.: Palaeont. Zeitschr., v. 16, no.

3-4, p. 170-197, pis. 17-19.

Taylor, M. E., 1966, Precambrian mollusc-like fossils frorc Inyo 

County, California: Science, v. 153, no. 3732, p. 19.?-201.

Turner, H. W., 1909, Contributions to the geology of the Silver 

Peak quadrangle, Nevada: Geol. Soc. America Bull., v. 20, 

p. 223-264.

Walcott, C. D., 1908, Cambrian geology and paleontology 

Number 5, Cambrian sections of the Cordilleran area: 

Smithsonian Misc. Colln., v. 53, p. 167-230.

 1912, Cambrian Brachiopoda: U.S. Geol. Survey Mon. 51, 

pt. 1, 873 p.; pt. 2, 363 p., 104 pis.

Yochelson, E. L., Taylor, M. E., and Cloos, Ernst, 196?, The 

Lower Cambrian genus SaUerella at Thomasville, Pennsylvania [abs.] : Geol. Soc. America, Northeastern Sec., 

3d Ann. Mtg., Washington, D.C., Program, p. 64.

PLATES 1-5
PLATE 1

[All photomicrographs taken in plain transmitted light]

FIGURES 1, 3. Salterella sp.

1. Specimen from Harkless Formation; University of California, Museum

of Paleontology, locality B-4035; X 25. USNM 165260. 

3. Specimen from USGS locality 180 (green series). Labeled "Cambrian. 

Summit on road, Silver Peak to Fish Lake Valley"; X 10. USNM 

165262.

2, 4, 5. Volborthella tennis Schmidt from slab labeled "Lower Cambrian (lower clay); 

Karlshof, Brigitten Fluss, near Reval, Estland." The slab was collected by 

A. Mickwitz in 1903, and it appears identical to other material in the U.S. 

National Museum collected by Fr. Schmidt and presumably identified by 

him as this species. USNM 165261.

2. A moderately well preserved specimen; X 50.

4. Several specimens including the one shown in fig. 2; X 10.

5. Two additional specimens; X 30.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 643-H PLATE 1

SALTERELLA AND VOLBORTHELLA
PLATE 2

[All photomicrographs taken in plain, transmitted light]

FIGURES 1-5. Salterella from USGS locality 6267-CO.

1. Specimen showing the central tube filled with calcite; laminae asymptotic to wall, meeting central tube at an angle of approximately 

30°; X 10. USNM 165263.

2. Specimen showing several alternating light- and dark-colored bands; 

X 10. USNM 165264.

3. Specimen showing dark bands and apertural breakage; most grains 

in laminae not well oriented; X 30. USNM 165265.

4. Small specimens the one in the upper right showing the inner tube 

and the lower central specimen, one of those examined with electron 

probe; X 10. USNM 165266.

5. Small specimen from same thin section as fig. 2, although not the same 

specimen; variable angle between laminae and central tube of 

between 35° and 52°; most grains in laminae are well oriented; 

X 30. USNM 165267.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 643-H PLATE 2

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SALTERELLA FROM NYE COUNTY, NEVADA
PLATE 3

[All photomicrographs taken in plain transmitted light]

FIGURES 1, 2. Salterella from USGS locality 6267-CO.

1. Note apparent double wall formed by asymptotic laminae (same 

specimen as shown on pi. 2, fig. 1); X 25. USNM 165263.

2. Same specimen as shown on pi. 2, fig. 2; X 25. USNM 165264.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 643-H PLATE 3

SALTERELLA FROM NYE COUNTY, NEVADA
PLATE 4

[All photomicrographs taken in plain transmitted light]

FIGURES 1-6. Satterella from USGS locality 6267-CO.

1. Oblique cross section; apparent double wall with outer part calcite 

and inner part calcite and microcrystalline quartz; X 30. USNM 

165268.

2. Cross section (same specimen as fig. 1) and longitudinal section (same

specimen as fig. 4); X 10.' USNM 165269.

3, 6. Specimen taken from same thin section as shown on pi. 2, fig. 4; most 

of laminae are silt-sized quartz grains in poor orientation; X 10 

and 20 (fig. 6 taken with crossed polarizers). USNM 165270.

4. Part of specimen shown in fig. 2; X 30. USNM 165269.

5. Well-preserved specimen showing staining of matrix in apertural 

cavity; note laminae extending along wall; X 10. USNM 165271.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 643-H PLATE 4

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SALTERELLA FROM NYE COUNTY, NEVADA
PLATE 5

[All photomicrographs taken in plain transmitted light]

FIGURES 1-6. SaUerella from USGS locality 6267-CO.

1. Specimen somewhat eroded at the lower part and without evidence of 

laminae; rock and shell filling are primarily calcitic; X 10. USNM 

165272.

2. Specimen with apex broken off but without loss of inner laminae; 

X 30. USNM 165273.

3. Several specimens, the one to the left apparently bent as suggested by 

abrupt changes in the geometry of the outer wall; laminae above 

bend distorted and broken but complete and regular below; X 10. 

USNM 165274.

4. Poorly preserved specimen having the apical portion separated from 

the remainder of the specimen; note destruction of laminae below 

break; X 30. USNM 165275.

5. Well-preserved specimen showing a part of the central tube near the 

apex, from same thin section as pi. 2, fig. 2; X 10. USNM 165276.

6. Distorted specimen showing outer wall and a mixture of inner deposits; 

no evidence of central tube; X 10. USNM 165277.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 643-H PLATE 5

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SALTERELLA FROM NYE COUNTY, NEVADA

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