Carboniferous Foraminifera and 

Algae of the Amsden Formation 

(Mississippian and Pennsylvanian) 

of Wyoming

GEOLOGICAL SURVEY PROFESSIONAL PAPER 848-B
Carboniferous Foraminifera and 

Algae of the Amsden Formation 

(Mississippian and Pennsylvanian) 

of Wyoming

By BERNARD L. MAMET

THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) 

OF WYOMING

GEOLOGICAL SURVEY PROFESSIONAL PAPER 848-B

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1975
UNITED STATES DEPARTMENT OF THE INTERIOR 

ROGERS C. B. MORTON, Secretary

GEOLOGICAL SURVEY 

V. E. McKelvey, Director

Library of Congress Cataloging in Publication Data

Mamet, Bernard L.

Carboniferous foraminifera and algae of the Amsden Formation (Mississippian and Pennsylvanian) of Wyoming.

(The Amsden Formation (Mississippian and Pennsylvanian) of Wyoming) (Geological Survey professional paper;

848-B)

Bibliography: p. 

Includes index. 

1. Foraminifera, Fossil. 2. Algae, Fossil. 3. Paleontology-Carboniferous. 4. Paleontology-Wyoming. I. Title.

II. Series. III. Series: United States. Geological Survey. Professional paper; 848-B. 

QE772.M294 557.3 r 08s [563'.1] 75-619056

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

Washington, B.C. 20402 

Stock Number 024-001-02631-7
CONTENTS

Page

Abstract _____________________________________ ________ Bl

Introduction _____-_ --- -- ____ _ 1

Taxonomic composition of the Amsden faunas _ _____ _ _ 2

Archaediscidae _-_ -_ __ _____ _ ------ 2

Biseriamminidae _ _ 2

Bradyinidae ___ _-_ - ______ _ 3

Cornuspiridae (sensu lato) ________________________ _ 3

Earlandiidae ____ ___-_-_____ -_-___-_--- 3

Endothyridae ______-____-___________________ 3

Eostaffellidae __ ___ __________________ _ 3

Fusulinidae _____ 3

Globoendothyridae _ _ _ ______ 3

Lasiodiscidae __ ___________ _______ 3

Ozawainellidae ___ ___-_______________-____ 4

Palaeotextulariidae __ _______ _______ _________ _ ______ ___ 4

Pseudoendothyridae ____________________________-_-____ 4

Tetrataxidae __ _ __ ____________________ __ ___ _ 4

Zonation ______________________________________________ 4

Zone 17 ________________________________________ j___ 4

Zone 18 ___________________________________ ___ 5

Zone 19 ___________________________________________ 6

Zone 20 ______________________________________________ 6

Zone 21 ______________________________________________ 6

The Mississippian-Pennsylvanian boundary _________________________ 7

List of microfossils ____________________________________________________ 7

References cited ___________________________________________ 14

Index __________________________________________________ 17

ILLUSTRATIONS

[Plates follow index]

PLATES 1, 2. Representative thin sections of foraminifers and algae from the 

Amsden Formation.

Page

FIGURE 1. Diagram showing stratigraphic ranges of Amsden foraminifers related to

standard time-stratigraphic units _______________________ B4

TABLE

Page

TABLE 1. Checklist of Amsden foraminifer collections ___________________ B3

m

THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING

CARBONIFEROUS FORAMINIFERA AND ALGAE

OF THE AMSDEN FORMATION 

(MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING

By BERNARD L. MAMET

ABSTRACT

Calcareous microfossil assemblages from the Amsden Formation of Wyoming consist of at least 100 taxa, predominantly foraminifers but including some algae and forms of 

uncertain biologic affinity. Approximately 70 taxa are reported herein. No microfossils were found in the Darwin 

Sandstone Member, but significant microfossil assemblages 

were recovered from the Horseshoe Shale, Moffat Trail Limestone, and Ranchester Limestone Members of the Amsden. 

The reported assemblages permit recognition of Zones 17-21, 

an age range of earliest Namurian (middle Chesterian) into 

early Westphalian (Atokan).

INTRODUCTION

The presence of endothyrid foraminifers and 

primitive fusulinids in the Upper Mississippian and 

Lower Pennsylvanian strata of Montana and Wyoming is well documented (Scott, 1945a, 1945b; 

Zellerfide Cooper, 1947; Zeller, 1950; Easton, 1962). 

Little attempt has been made, however, to use them 

as stratigraphic indices. This short contribution is 

aimed at underlining the usefulness of these microfossils for Carboniferous correlations. In particular, 

the fossils are of some interest for recognition of the 

controversial Mississippian-Pennsylvanian boundary.

Details of the stratigraphy and the occurrences of 

these fossils are given by Sando, Gordon, and Dutro 

(1974). Representative thin sections of the Amsden 

microfossils are shown in plates 1 and 2. Lists of 

microfossils are given in terms of the stratigraphic 

units and localities described in Sando, Gordon, and 

Dutro (1974), and the localities are documented in 

table 1.

Calcareous secreted Foraminifera are unevenly 

distributed in the Amsden Formation. The Darwin 

Sandstone Member, for instance, yields no identifiable fauna. Calcareous beds of the Horseshoe Shale, 

Ranchester Limestone and Moffat Trail Limestone 

Members yield variable amounts of microfauna; the 

richest assemblages are found in the pelmatozoanlump-bearing grainstones and packstones; in contrast, red silty mudstones and dolomites yield very 

poor assemblages. However, despite the uneven distribution, the variable preservation, and the fact 

that the collections studied here were not made specifically for foraminifers, sufficient material was 

found to establish a biostratigraphic zonation.

At least 100 different foraminiferal taxa have 

been observed in about 120 thin sections of samples 

collected from 40 localities. Most of these taxa are 

very scarce or could not be identified to the specific 

level. Moreover, apterrinellids, serpulopsids, and calcitornellids cannot be identified with confidence on 

random thin sections, and their role and value, if 

any, in stratigraphy remain obscure.

The most important forms for biostratigraphic 

correlations are reported here:

Archaediscus sp.

Archaediscus of the group A. chernoussovensis Mamet

A. krestovnikovi Rauzer-Chernoussova

Archaediscus of the group A. krestovnikovi RauzerChernoussova

Asteroarchaediscus sp.

A. baschkiricus (Krestovnikov and Teodorovitch)

Asteroarchaediscus of the group A. baschkiricus 

(Krestovnikov and Teodorovitch)

Biseriella sp.

B. moderata (Reitlinger)

Bl
B2 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING

B. parva (Chernysheva)

Biseriella of the group B. parva (Chernysheva) 

Bradyinal sp.

Climacammina sp.

"Cornuspira" sp.

Diplosphaerina sp.

Earlandia sp.

E. clavatula (Howchin)

E. elegans (Eauzer-Chernoussova)

E. vulgaris (Eauzer-Chernoussva and Eeitlinger)

cf. Endostaffellal sp.

Endothyra sp.

Endothyra of the group E. bowmani Phillips emend. 

Brady

E. excellens (Zeller)

"Endothyra" of the group "E" prisca EauzerChernoussova and Eeitlinger

Endothyra of the group E. similis Eauzer-Chernoussova 

and Eeitlinger

E. tantala (Zeller)

Endothyranella sp.

cf. Eolasiodiscus sp.

Eoschubertella sp.

"Eosigmoilina" sp.

Eostaffella sp.

Eostaffella of the group E. acutissima Kireeva

E. circuit (Thompson)

Eostaffella of the group £7. pseudostruvei (EauzerChernoussova)

E. pinguis (Thompson)

Eostaffellina sp.

E. paraprotvae (Rauzer-Chernoussova)

Eotuberitina sp.

Globivalvulina sp.

Globivalvulina of the group G. bulloides (Brady)

Globoendothyra sp.

Glomospira sp.

Lipinella sp. (nom. nud.)

Millerella sp.

M. pressa Thompson

M. aff. M. pura Malakhova

Monotaxinoides sp.

Neoarchaediscus sp.

N. incertus (Grozdilova and Lebedeva)

Neoarchaediscus of the group N. incertus (Grozdilova 

and Lebedeva)

Neoarchaediscus of the group N. parvus (EauzerChernoussova)

AT", parvus (Eauzer-Chernoussova)

cf. Palaeonubecularial sp.

Palaeotextularia sp.

Palaeotextularia of the group P. consobrina Lipina

Palaeotextularia of the group P. longiseptata Lipina

Planoendothyra sp.

Planospirodiscus sp.

P. minimus (Grozdilova and Lebedeva)

Pseudoendothyra sp.

Pseudoendothyra of the group P. kremenskensis 

Eozovskaia

Pseudoendothyra of the group P. ovata (Reitlinger)

Pseudoendothyra of the group P. struvei (von Moller)

Pseudoglomospira sp.

Tetrataxis sp.

"Tetrataxis" of the group "T." eominima RauzerChernoussova

Trepeilopsis sp.

Tuberitina sp.

Volvotextularia sp.

Zellerina sp.

Z. discoidea (Girty)

In addition to foraminifers, algae and incertae 

sedis are also present. Among the alg;re, Spongiostromata are the most widespread. Also noticeable 

are the Rhodophycophyta (Stacheia, Stacheoides, 

etc.). Calcispheres are mostly represented by Calcisphaera laevis Williamson. Asphaltina is present. 

None of these forms has precise stratigraphic value.

TAXONOMIC COMPOSITION OF THE 

AMSDEN FAUNAS

ARCHAEDISCIDAE

The most useful index for stratigraphic zonation 

of the latest Visean-early Namurian is the Archaediscus - Neoarchaediscus - Planospirodiscus - Asteroarchaediscus-Quasiarchaediscus-'Eosigmoilina" phylogeny. These genera have been found in abundance 

in most of the fossiliferous Amsden Formation thin 

sections. As is generally the case in rocks of Namurian age, Archaediscus is represented only by 

relict Archaediscus of the group A. krestovnikovi, all 

other groups (A. moelleri, A. chernoussovensis) being rare or absent. The Archaediscidr.e with obstructed lumen dominate, and Asteroc,rchaediscus 

and Neoarchaediscus are common in all clean wackestones and packstones.

The progressive elimination of the pseudofibrous 

wall structure and its replacement by a "porcellaneous" wall, concomitant with the disappearance of 

the inner tectum, lead to "Eosigmoilina" which is 

derived, for the first time, in Zone 19 from Quasiarchaediscus. This evolutionary change is well observed in the middle part of the Amsden Formation 

at the Berry Creek section.

BISERIAMMINIDAE

Biseriamminids are abundant in the / msden Formation from Zone 18 upwards. Earliest forms are 

Biseriella of the group B. parva (Cternysheva), 

whose outburst underlies Zone 18 (upper Chester 

time equivalent in the Midcontinent and the Cordillera).

Globivalvulina sensu stricto, with its characteristic diaphanotheca, appears for the first time in the 

basal Pennsylvanian beds. It is an important faunal 

element of Zone 21 (Globivalvulina of the group G. 

bulloides (Brady)).
CARBONIFEROUS FORAMINIFERA AND ALGAE 

TABLE 1. Checklist of Amsden foraminifer collections

B3

Collection 

No.

1

3

4

6

13

14

45 

50

64

65

67

68

74

77

78

79

82

90

92

93

100

103

104

105

109

121

122

124

125

126

132

145

153

154

160

Permanent 

USGS 

catalog No.

5441-PC _____

8071-PC

3139-PC _____

3140 PC _ _ _

3085-PC __ _

3843 PC ____

21729-PC __

21719-PC ____

19187-PC. 

22206 PC __

22207-PC __

22208-PC ____

16215-PC __

22204-PC _ 

22985-PC ___

22986 PC __ _

6960 A-PC __

6960B-PC _ _

22981-PC .

22984-PC __

22995-PC __

S965-PC _____

6951-PC _ _

6965D-PC __

17905-PC __

17906-PC __

17907-PC __ _

23002-PC _ __

16208-PC _ __

16209-PC __

18799-PC __ _

18785-PC __

22998-PC _ _

16211-PC _ _

23006-PC __ _

24059-PC _ __

24060-PC __

24057-PC .

Name of locality

_ do __ __ _ _

_ _do _ __ __ _

__ do _____ ___ -

Rawlins US 287 _ __

Meadow Ranch _ ___

Livingston Ranch ____

__do _ _ ___ _____

do _____ __ -

__ do __ -----

_ _do _ _ _ __ __

__ do _ - ___ _ __

_do _____ _ _ _

 do __ . __ _

__ do ____ .._ _ 

_ do _ _ ___ ______

Covey Cutoff Trail _

-do ____ _ _

__ do _ _ __ _

_ _do _ ____ _____

__ do ___ __

do _ _

_ do __ _ _ __ _

-do _ _ _ _ _

-do _ _ _

 do __ __ _ _

_ ..do _ . __ _

_do __ __ _ __

Elk Ridge _ _ __

Mountain range

do . ._ ____

__ do __ __ _ ._

do __ __ _

__ do __ ___ _

_ do __ ___ __

__ do ______________

_ -do ___ ____ _

Washakie Range __ 

_ do _ ___ _

__ do _ ____________

_ _do _ ___ _

_do _._. __ _

 do _______ _

__ do ____ ____

_ -do _ _

do ____________

_do __ ____ .

_ -do _ ___ __ __

_ _do ___ ___ _

__ do __ ___ __

_do _ __ ____

_ _do __ .. __ _

__ do __ ___ _

_do

-do __ __

_ -do __ - __ ,

 do ________ __

-do _ _ - - _

_ _do __ __ __

_do _ __ _ __

 do __ __ ._ _

 do __ - _ __

__ do ____ __ _

County

 do _ 

__ do

do _ _

 do __ _ _

_ _do

_ do ______

_ do - .

Fremont _ _

_ do _ 

 do __ .

_ do _ __

_ do _ - .

__ do ____

_ do _ _ _

_ do - -

_ do _

. do _

 do _ __ .

do _

-do . __ 

__ do - __

_ do _

_ do _ _

 do _ _ .

_ -do _ - -

 do _

_do -

 do _ -

- do - _

_ do _

- do _ __

_ do _

-do _ . _

 do _ ._

Location

Probably SW*4 sec. 11, T. 21 N., R.

88 W. 

_ do __ __ ____ __ _ _ 

NW%SW% sec. 11, T. 21 N., R. 88 W 

SE^iNE^, sec. 10, T 21 N., R. 88 W _ _

Probably NW&NW% see. 32, T. 22 N.,

R. 87 W. 

SWVtNEi/i sec. 25, T. 22 N., R. 88 W 

NW% sec. 33, T. 23 N., R. 88 W

SWiiSW1^ sec. 29, T 43 N., R. 106 W __ 

Sec. 19, T. 41 N., R. 88 W __ ________

SW% sec. 34, T. 57 N., R. 87 W ________

_ _do _ _ __ _________ _____ ____

_ _do ___ ________ __ _______

SEii sec. 32, T. 57 N., R. 87 W

NW^NWVi sec. 19, T. 28 N., R. 113 W 

NW%NEi4 sec. 3, T. 33 N., R. 117 W _

_ _do _______ _ ___ ____ _

__do ___ _ _ _______ ____

_ do _ __ ___ __ . _

NW^NE^, sec. 27, T. 34 N., R. 117 W 

rln

_ do __ __ _ _ __ _ __

_ do _ __ __ _ _____ __ _ __ _

Center sec. 19, T. 34 N., R. 117 W

__ do _ ______ __ ___ ____ _ _ _

_ do __ _ __ _ _ . - _ --

NE'/i sec. 14, T. 38 N., R. 118 W __ 

Sec 2, T. 38 N., R. 115 W ___

___ do _ __ _ _ ___ __ __ _ 

Sec. 3, T. 38 N., R. 115 W __ _ _ _

-do _ _ __ ____ . _ __ 

__ do _ __ _ _ _ _ _ __

SWH sec. 16, T. 41 N., R. 117 W __ _ _

NW% sec. 22, T. 47 N., R. 116 W __ -

__ do _ _ - _ _ _ __ _

SWVi sec. 26, T. 47 N., R. 116 W __ 

Member

Do.

Do.

Do.

Do.

Do. 

Do.

Horseshoe Shale.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

BRADYINIDAE

Bradyinaf has only been observed once, at the Tip 

Top Well locality.

CORNUSPIRIDAE (sensu lato)

"Cornuspira" is present but scarce. The absence 

of Brunsia is puzzling.

EARLANDIIDAE

Common in most facies, the family is essentially 

represented by Earlandia. No zonation can be derived from this genus in Namurian time.

ENDOTHYRIDAE

Although this family is of great stratigraphic 

value in the Tournaisian-Visean, its usefulness dwindles in the Late Visean and disappears in the Namurian. Only Endothyra and Pianoendothyra have 

been observed, the latter genus being scarce. Even 

at a specific level, little evolution can be detected, 

hence no zonation is feasible at the MississippianPennsylvanian boundary.

EOSTAFFELLIDAE

Four genera of Eostaffellidae are known: Eostaffella, Endostaffellaf, Eostaffellina, and Zellerina. 

Zellerina is abundant at all levels of the Chester and 

has often been confused for Millerella.

Eostaffellina, where it occurs in abundance (Amsden Creek section), is a good marker for the upper 

Chester and Morrow age equivalents.

FUSULINIDAE

Eoschubertella is restricted to the upper part of 

the Amsden Formation (Ranchester Limestone 

Member).

GLOBOENDOTHYRIDAE

The family is poorly represented by scarce Globoendothyra.

LASIODISCIDAE

The most primitive member of this family, 

Eolasiodiscus, is abundant at the Covey Cutoff section.
B4 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING

OZAWAINELLIDAE

The unique representative of this family is Miller ella sensu stricto; its first appearance is basal 

Pennsylvanian (Zone 20).

PALAEOTEXTULARIIDAE

As in most of the American Midcontinent and in 

the Williston basin, the family is poorly developed 

in early Namurian with occasional Climacammina 

and Palaeotextularia. These genera become rather 

abundant in the Pennsylvanian.

PSEUDOENDOTHYRIDAE

Pseudoendothyra is the only known representative 

of the family in the Amsden Formation.

TETRATAXIDAE

The family is unusually poorly represented by 

Tetrataxis and Monotaxinoides.

This composition of the families is typical of any 

North American Namurian carbonate platform 

microfauna. The only difference observed between 

the Amsden fauna and that of comparable carbonate 

assemblages of the Midcontinent and the Cordillera 

is the very poor development of the Tetrataxidae 

and Bradyinidae and the absence of Endothyranopsidae.

ZONATION

Five Carboniferous foraminiferal zones can be 

identified in the Amsden Formation; they represent 

the time equivalents of the middle Chester to the 

Atoka classical sequence of the Midcontinent (fig. 

1).

ZONE 17

Definition. The base of the zone is defined at the 

outburst of Asteroarchaediscus and in particular at 

the first proliferation of Asteroarchaediscus baschkiricus (Krestovnikov and Teodorovitch). The zone 

contains many elements inherited from the underlying Visean Zone 16S, such as Neoarchaediscus and 

Planospirodiscus. The top of the zone yields the first 

biseriamminids referable to Biseriella. Examples of 

Zone 17 assemblages are illustrated on plate 1, figures 1-3.

Comparison. In the Carboniferous Tethys, the 

base of Zone 17 is characterized by the disappearance of numerous Visean elements such as Valvulinella, Howchinia, and residual lituotubellids and

Z

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20

19

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17

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FIGURE 1. Stratigraphic ranges of Amsden forrminifers related to standard time-stratigraphic units.
CARBONIFEROUS FORAMINIFERA AND ALGAE B5

forschiids. These taxa are unknown outside the 

Tethyan realm. Zone 17 also normally yields Endothyranopsis sphaerica (Rauzer-Chernoussova and 

Reitlinger) ; no Endothyranopsidae has been encountered in the Amsden Formation.

Occurrence in Amsden Formation. The Zone 17 

assemblage of the Amsden Formation is known only 

from the Moffat Trail Limestone Member of extreme western Wyoming, where it has been positively identified in collections 103, 104, and 109 

from the Haystack Peak and South Indian Creek 

localities. These faunules contain the oldest foraminifers known from the Amsden. Other collections 

(75, 79, 90, 92, 93, 126) from the Moffat Trail Limestone Member at Moffat Trail, Covey Cutoff Trail, 

and Hoback Canyon contain assemblages that represent Zone 17 or 18 but lack critical elements that 

permit differentiation of the two zones.

Correlation. Zone 17 is of middle Chesterian age; 

it includes a foraminiferal assemblage that occurs 

in the Glen Dean and Menard Limestones of the 

Midcontinent region. The base of the Glen Dean is 

characterized by the first outburst of Asteroarchaediscus baschkiricus (Krestovnikov and Teodorovitch), while the underlying Golconda Formation 

yields only Neoarchaediscus and Planospirodiscus. 

Zone 17 is also known from the base of the Surrett 

Canyon Formation and from the upper part of the 

White Knob Limestone of central Idaho (Mamet 

and others, 1971; Skipp and Mamet, 1970). It has 

been observed in the Monroe Canyon Limestone of 

southeastern Idaho (Sando and others, 1969). In 

Nevada, the upper part of the Battleship Wash 

Formation is early Namurian (Mamet and Skipp,

1970).

In Alaska, Zone 17 is observed in the Calico Bluff 

Formation and in the middle part of the Alapah 

Limestone of the Lisburne Group in the Sadlerochit 

Mountains, the Romanzoff Mountains, and the central part of the Brooks Range (Armstrong and 

others, 1970). It is poorly developed in the Kogruk 

Formation at Cape Lewis (Armstrong and others,

1971).

Zone 17 is also widespread in Canada, where it 

occurs in the upper part of the Windsor Group of 

Nova Scotia (Mamet, 1970), in the middle part of 

the Etherington Formation in Alberta and British 

Columbia (Mamet, 1968), in the middle part of the 

Nizi Formation in British Columbia (Mamet and 

Gabrielse, 1969), in the middle part of the Alapah 

Limestone and at the top of the Hart River Formation in the Yukon Territory (Mamet and Mason, 

1970; Mamet and Ross in Bamber and Waterhouse, 1971).

ZONE 18

Definition. This zone is characterized by the outburst of Biseriella of the group B. parva (Chernysheva). Eostaffellina is also present. The top of the 

zone is marked by the first appearance of Quasiarchaediscits.

Comparison. In the Carboniferous Tethys, these 

characteristic elements are present, but Eostaffellina 

is more abundant. Spherical "Pseudoendothyra" are 

also encountered in the Tethys; in comparison, they 

are unknown in North America. Loeblichia is also 

restricted to the Tethyan realm.

Occurrence in Amsden Formation. The principal 

occurrences of the Zone 18 assemblage are in the 

Moffat Trail Limestone Member, where the assemblage has been identified in collections 74, 77, 78, 

105, 122, 124, and 145 from the Moffat Trail, Haystack Peak, Hoback Canyon, and Phillips Canyon 

localities of western Wyoming. The zone may be 

represented in collection 125 from the Moffat Trail 

Limestone Member at Hoback Canyon.

The Zone 18 assemblage also has been found in 

the Horseshoe Shale Member at Livingston Rar?,h 

in the Washakie Range (colln. 45), where it indicates partial time equivalence of the Horseshoe Shale 

and Moffat Trail Limestone Members. Possible representation of Zone 18 in the Horseshoe Shale Member at Berry Creek (colln. 154) and in the Ranch-^ster Limestone Member at Elk Ridge (colln. 160), 

localities in the Teton Range, is doubtful because 

these occurrences are more in keeping with the distribution of the Zone 19 assemblage.

Correlation. Zone 18 is of late Chesterian age; 

it includes a foraminiferal assemblage that occurs 

in the Clore and Kinkaid Limestones of the Midcontinent region. In Idaho, Zone 18 is known from 

the middle part of the Surrett Canyon Formation, 

the top of the White Knob Limestone (Mamet r.nd 

others, 1971) and the upper part of the Monroe 

Canyon Limestone (Sando and others, 1969). It is 

also observed in the Indian Spring Formation of 

Nevada (Mamet and Skipp, 1970).

In Alaska, the zone is well displayed in the upper 

part of the Alapah Limestone in the Sadlerochit 

Mountains, Romanzoff Mountains, and the central 

part of the Brooks Range (Armstrong and others, 

1970). It is also known from the upper part of the 

Kogruk Formation at Cape Lewis (Armstrong r.nd 

others, 1971).

In Canada, Zone 18 is unknown in the Maritime 

Provinces, where nonmarine or brackish sediments 

overlie early Namurian carbonates. It is present in 

the upper part of the Etherington Formation of 

Alberta and British Columbia (Mamet, 1968) and
B6 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING

in the Nizi Formation of northern British Columbia 

(Mamet and Gabrielse, 1969). It is also observed 

in the upper part of the Alapah Limestone and in 

the Ettrain Formation of the Yukon Territory 

(Mamet and Mason, 1970; Mamet and Ross in 

Bamber and Waterhouse, 1971).

ZONE 19

Definition. This zone is characterized by the 

acme of Eosigmoilina-Quasiarchaediscus. In addition, it contains some elements inherited from early 

Namurian zones such as Biseriella and Asteroarchaediscus.

Comparison. The same faunal characteristics are 

known in the Tethys, where the zone is equivalent 

to most of the Homoceras Zone.

Occurrence in Amsden Formation. The Zone 19 

assemblage is known definitely only from collection 

153 in the Horseshoe Shale Member at Berry Creek 

in the Teton Range. It is probably also present in 

collection 154 at Berry Creek and may be represented in the Ranchester Limestone Member at Elk 

Ridge (colln. 160).

Correlation. Zone 19 is considered to be of latest Chesterian age although it is absent from the 

Midcontinent region owing to post-Kinkaid, prePennsylvanian hiatus. This zone is known from the 

uppermost part of the Surrett Canyon Formation of 

central Idaho and is particularly well displayed in 

the upper part of the Indian Spring Formation in 

Nevada (Mamet and Skipp, 1970).

In Alaska, Zone 19 has been observed in the uppermost part of the Alapah? Limestone in the West 

Sadlerochit Mountains. In Canada, the zone has been 

identified in the Trail River-Trout Lake region in 

the Yukon Territory (Mamet and Mason, 1970). It 

is also present in the uppermost Alapah Limestone 

of the British and Buckland Mountains (Mamet and 

Ross in Bamber and Waterhouse, 1971).

ZONE 20

Definition. The zone is identified on the first occurrence of true fusulinids (Millerella sensu stricto). The first diaphanotheca-bearing Globivalvulina 

also occur for the first time, but they are scarce. 

Examples of Zone 20 assemblages are shown on 

plate 1, figures 6-8 and plate 2, figures 1-8.

Comparison. The same faunal characteristics are 

known in the Tethys, where Semistaffella and primitive Pseudostaffella ? occur in addition.

Occurrence in Amsden Formation. The principal occurrences of the Zone 20 assemblage are in the 

Ranchester Limestone Member, where it has been 

found at two localities in western Wyoming (collns. 

100, 132) and four localities in central Wyoming 

(collns. 13, 14, 50?, 63, 64, 65, 67, 68). It also occurs in the Horseshoe Shale Member of the Rawlins hills (collns. 1-5).

Con-elation. In the United States, the first true 

fusulinids occur in the basal Pennsylvania and may 

therefore be used to underline the sequence. Zone 

20 corresponds to the Morrowan Series of the standard North American sequence.

Zone 20 is well displayed at the base of the Pennsylvanian sequence of central Idaho (Mamet and 

others, 1971) and in the basal carbonates of the Bird 

Spring Formation in Nevada (Mamet and Skipp, 

1970). In Alaska, Zone 20 is widespread at the base 

of the Wahoo Limestone in the Sadlerochit Mountains (Armstrong and others, 1971).

ZONE 21

Definition. This zone is recognized en the outburst of Eoschubertella and Pseudostaffella. Diaphanotheca-bearing Globivalvulina also become 

abundant at the base of the zone.

Comparison. Direct comparison with the Carboniferous Tethys is difficult. Further studies are 

necessary in order to relate Zone 21 with the standard Baschkirian-Moscovian succession. If the Donbass sequence established by Brazhnikova and others 

(1967) is correct, Zone 21 is still Baschkirian, a correlation which conflicts with the generally accepted 

view that the base of the Atokan Series ie equivalent 

to the basal Moscovian (Thompson in Loeblich and 

Tappan, 1964).

Occurrence in Amsden Formation. The Zone 21 

assemblage is known only from the Ranchester 

Limestone Member in the Rawlins hills (colln. 6) 

and at the Tip Top Well in the Green River Basin 

(colln. 71).

Correlation. In the United States, Zone 21 is 

well displayed in the Atoka age equivalent sequence 

of central Idaho (Mamet and others, 1971). It is 

poorly displayed in the Bird Spring Formation of 

Nevada.

In Alaska, the zone is omnipresent in the oolitic 

facies of the middle part of the Wahoo Limestone 

in the Sadlerochit Mountains. In Canada, it is present in the Lisburne Group of the Malcolm River 

section and in the Ettrain Formation in the Keele 

Range (Yukon Territory) (Mamet and Ross in 

Bamber and Waterhouse, 1971).
CARBONIFEROUS FORAMINIFERA AND ALGAE B7

THE MISSISSIPPIAN-PENNSYLVANIAN 

BOUNDARY

As previously mentioned (Mamet and others, 

1971), the formations exposed in the Midcontinent 

are unsuitable for definition of the MississippianPennsylvanian boundary because the two sequences 

are separated by a hiatus. The exact biostratigraphic span of this hiatus is unknown, but the 

latest Mississippian (Kinkaid Limestone, Grove 

Church Member) yields a good Zone 18 assemblage, 

while the first Pennsylvanian fauna is Zone 20. Thus 

it is certain that Zone 19 is entirely missing and 

plausible that Zones 18 and 20 are incomplete.

Zone 19 has been considered here as latest Chester i an age equivalent, although it is missing in the 

type Chester region. This age assignment is biostratigraphically consistent with the observation 

that Zone 19 is the acme of the evolution of the 

Archaediscidae and is phylogenically linked with the 

underlying Zone 18. Moreover, Zone 20 marks the 

appearance of the first true fusulinids, which become 

the dominant assemblage of the Pennsylvanian microfauna. This placement of the boundary respects 

both lithostratigraphic and biostratigraphic conventions.

A somewhat similar position was adopted by 

Lane, Sanderson, and Verville (1972), who considered the Zone 19 Indian Springs Formation of 

Nevada to be entirely Chesterian. They defined the 

base of the Pennsylvanian on the first occurrence of 

the conodonts Adetognatlius lautus and A. gigantus, 

which occur for the first time slightly above the top 

of the Indian Springs Formation. According to 

Brenckle, Zone 19 is still present in the lowermost 

part of the Bird Spring Formation in the Arrow 

Canyon composite section of Nevada (1973).

One must underline, however, the confusion observed in the literature concerning the status of 

Millerella. When Thompson (1942) originally defined the genus, he correctly assumed that it was 

diagnostic of the Pennsylvanian. However, the 

Thompson concept of the genus subsequently varied 

greatly, and he incorporated in Millerella species 

which would now be referred to Eostaffella or Zellerina (Thompson, 1944, 1945). Scott (1945a, 1945b) 

correctly identified Millerella, but references to Millerella in the upper Chester (Henbest, 1946, 1947; 

Cooper, 1946, 1947; Mellen, 1947; Thompson, 1948; 

E. J. Zeller, 1950; D. E. N. Zeller, 1953; Sage, 1954) 

have to be re-evaluated. All published material of 

such low Millerella occurrences (Cooper, 1947; E. J. 

Zeller, 1950; Sage, 1954) show taxa which should be 

referred to the Eostaffellidae, not to the Ozawainellidae. Pennsylvanian Millerella of Easton (19^2) 

and of Moore (1964) correctly fit the Thompson 

(1942) diagnosis.

LIST OF MICROFOSSILS

Collection 1. Horseshoe Shale Member, Cherokee Spring 

locality. 

Age. Zone 20, late Namurian (Reticuloceras Zone), Fennsylvanian (Morrowan).

Foraminifers present.

Apterrinellidae

Arcliaediscus sp.

Asphaltina sp.

Asteroarchaediscus sp.

Asteroarchaediscus of the group A, baschkiricus 

(Krestovnikov and Teodorovitch)

Calcisphaera sp.

Earlandia sp.

Endothyra sp.

Endothyranella sp.

Lipinella sp. (nom. nud.)

Millerella sp.

Neoarchaediscus of the group N. incertus (Grozdilovr 

and Lebedeva)

Planospirodiseus sp.

Pseudoglomospira sp.

Zellerina sp.

Collection 2. Horseshoe Shale Member, Cherokee Siting 

locality. 

Age. Zone 20, late Namurian (Reticuloceras Zone), Fennsylvanian (Morrowan).

Foraminifers present.

Apterrinellidae

Archaediscus sp.

Asteroarchaediscus sp.

A. baschkiricus (Krestovnikov and Teodorovitch)

Biseriella sp.

B. moderata (Reitlinger)

Calcisphaera sp.

"Cornuspira" sp.

Diplosphaerina sp.

Earlandia sp.

"Endothyra" sp.

Eostaffella sp.

Eotuberitina sp.

Girvanella sp.

Globivalvidina sp.

Lipinella sp. (nom. nud.)

Millerella sp.

Neoarchaediscus of the group N. incertus (Grozdilovr

and Lebedeva) 

N. parvus (Rauzer-Chernoussova)

Pianospirodiscus sp.

Pseudoendothyra sp.

Collection 3. Horseshoe Shale Member, Cherokee Spring 

locality.

Age. Zone 20, late Namurian (Reticuloceras Zone), Pennsylvanian (Morrowan). 

Foraminifers abundant. 

Apterrinellidae 

Asphaltina sp.
B8 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING

Asteroarchaediscus sp.

Asteroarchaediscus of the group A. baschkiricus

(Krestovnikov and Teodorovitch) 

Biseriella sp. 

Calcisphaera sp. 

C. laevis Williamson 

Earlandia sp. 

Endothyra sp. 

"Endothyra" of the group "E." pri-sca RauzerChernoussova and Reitlinger 

Millerella sp. 

M. pressa Thompson

Neoarchaediscus incertus (Grozdilova and Lebedeva) 

N. parvus (Rauzer-Chernoussova) 

Planoendothyra sp. 

Planospirodiscus sp. 

Pseudoglomospira sp. 

Zellerina sp.

Collection 4. Horseshoe Shale Member, Cherokee Peak locality.

Age. Zone 20, late Namurian (Reticuloceras Zone), Pennsylvanian (Morrowan). 

Foraminifers present to abundant. 

Apterrinellidae 

Archaediscus sp.

Archaediscus of the group A. krestovnikovi RauzerChernoussova 

Asphaltina sp. 

Asteroarchaediscus sp. 

Asteroarchaediscus of the group A. baschkiricus

(Krestovnikov and Teodorovitch) 

Calcisphaera sp. 

Earlandia sp. 

Endothyra sp. 

"Endothyra" of the group "E." prisca RauzerChernoussva and Reitlinger 

Lipinella sp. (nom. nud.) 

Millerella sp. 

M. pressa Thompson

Neoarchaediscus incertus (Grozdilova and Lebedeva) 

N. parvus (Rauzer-Chernoussova) 

Planospirodiscus sp. 

Pseudoendothyra sp. 

Pseudoglomospira sp.

Collection 5. Horseshoe Shale Member, Cherokee Peak locality.

Age. Zone 20, late Namurian (Reticuloceras Zone), Pennsylvanian (Morrowan). 

Foraminifers abundant. 

Apterrinellidae 

Archaediscus sp.

Archaediscus of the group A. krestovnikovi RauzerChernoussova 

Asphaltina sp. 

Asteroarchaediscus sp.

A. baschkiricus (Krestovnikov and Teodorovitch) 

Calcisphaera sp. 

C. laevis Williamson 

"Cornuspira" sp. 

Diplosphaerina sp. 

Earlandia sp. 

Endothyra sp. 

Eotuberitina sp.

Neoarchaediscus sp. 

N. incertus (Grozdilova and Lebedeva) 

N. parvus (Rauzer-Chernoussova) 

Planospirodiscus sp. 

Pseudoglomospira sp. 

Pseudoendothyra sp. 

Rhodophycophyta 

Zellerina sp.

Collection 6. Ranchester Limestone Member, Rawlins US 

287 locality.

Age. Zone 21, early Westphalian, Pennsylvanian 

(Atokan).

Foraminifers present. 

Archaediscus sp. 

Asteroarchaediscus sp. 

Calcisphaera sp. 

C. laevis Williamson 

Eoschubertella sp. 

Eostaffella sp. 

Millerella sp. 

Pseudoglomospira sp. 

Tetrataxis sp.

Collection 13. Ranchester Limestone Member, Meadow 

Ranch locality.

Age. Zone 20, late Namurian (Reticuloceras Zone),

Pennsylvanian (Morrowan).

Foraminifers scarce.

Asteroarchaediscus sp.

Asteroarchaediscus of the group A. baschkiricus

(Krestovnikov and Teodorovitch) 

Calcisphaera sp. 

C. laevis Williamson 

Earlandia sp. 

Endothyra of the group E. boivmani Phillips emend.

Brady

Eostaffella sp. 

EostaffeUina sp. 

Globivalvulina sp. 

Lipinella sp. (nom. nud.) 

Millerella sp. 

M. pressa Thompson 

M. aff. M. pura Malakhova 

Neoarchaediscus sp. 

Planoendothyra sp. 

Pseudoendothyra sp. 

Tetrataxis sp. 

Zellerina sp.

Collection 14. Ranchester Limestone Member, Buck Spring 

locality.

Age. Zone 20, late Namurian (Reticuloceras Zone), Pennsylvanian (Morrowan).

Foraminifers abundant.

Asteroarchaediscus sp.

A. baschkiricus (Krestovnikov and Teodorovitch)

Biseriella sp.

B. moderata (Reitlinger)

Calcisphaera sp.

Endothyra sp.

Earlandia sp.

Eostaffella sp.

"Eotuberitina" sp.

Globivalvulina of the group G. bulloides (Brady)
CARBONIFEROUS FORAMINIFERA AND ALGAE B9

Lipinella sp. (nom. nud.) 

cf. Palaeonubeculariat sp. 

Pseudoglomospira sp.

Tuberitina sp.

Collection 45. Horseshoe Shale Member, Livingston Ranch 

locality. 

Age. Zone 18, early Namurian (Eumorphoceras Zone),

Late Mississippian (late Chesterian).

Foraminifers present. 

Asteroarchaediscus sp.

Biseriella sp.

Biseriella of the group B. parva ( Chernysheva)

Calcisphaera sp.

Earlandia sp.

Endothyra sp.

Eostaffella sp.

Eostaffellina sp.

Neoarchaediscus sp.

Palaeotextularia sp.

Planospirodiscus sp.

Pseudoendothyra sp.

Zellerina discoidea (Girty)

Collection 50. Ranchester Limestone Member, Trout Creek 

locality. 

Age. Zone 20?, late Namurian (Reticuloceras Zone) ?,

Pennsylvanian (Morrowan) ?

Foraminifers scarce and poorly preserved.

Apterrinellidae

Calcisphaera sp.

Cornuspiridae

Earlandia sp.

cf. Lipinella sp. (nom. nud.)

Pseudoglomospira sp.

Collection 63. Ranchester Limestone Member, Amsden Creek 

locality.

Age. Zone 20, late Namurian (Reticuloceras Zone), Pennsylvanian (Morrowan).

Foraminifers abundant.

Apterrinellidae

Archaediscus sp.

Archaediscus of the group A. krestovnikovi RauzerChernoussova

Asteroarchaediscus sp.

A. baschkiricns (Krestovnikov and Teodorovitch)

Biseriella sp.

Biseriella of the group B. parva (Chernysheva)

B. moderata (Reitlinger)

Calcisphaera sp.

Climacammina sp.

Cornuspiridae

Diplosphaerina sp.

Endothyra sp.

Endothyra of the group E. bowmani Phillips emend. 

Brady

Eostaffella sp.

Eostaffellina sp.

Eotuberitina sp.

Globivalvulina sp.

Millerella sp.

Neoarchaediscus of the group N. incertus (Grozdilova 

and Lebedeva)

Palaeotextularia sp.

Planoendothyra sp.

Pseudoendothyra sp.

Stacheiinae

Tetrataxis sp.

Collection 64. Ranchester Limestone Member, Amsden Creek 

locality.

Age. Zone 20, late Namurian (Reticuloceras Zone), Pennsylvanian (Morrowan).

Foraminifers abundant.

Apterrinellidae

Asteroarchaediscus sp.

Biseriella moderata (Reitlinger)

Calcisphaera sp.

Cornuspiridae

Endothyra sp.

Eostaffella sp.

E. circuli (Thompson)

Eostaffellina sp.

Globivalvulina sp.

Lipinella sp. (nom. nud.)

cf. Palaeonubeculariat sp.

Pseudoendothyra sp.

Zellerina discoidea (Girty)

Collection 65. Ranchester Limestone Member, Amsden C *eek 

locality.

Age. Zone 20, late Namurian (Reticuloceras Zone), Pennsylvanian (Morrowan).

Foraminifers abundant.

Apterrinellidae

Archaediscus sp.

Archaediscus of the group A. krestovnikovi RauzerChernoussova

Asteroarchaediscus sp.

A. baschkiricus (Krestovnikov and Teodorovitch)

Biseriella sp.

B. moderata (Reitlinger)

Calcisphaera sp.

Cornuspiridae

Endothyra sp.

Eostaffella sp.

E. circuli (Thompson)

Eostaffella of the group E. pseudostruvei (RauzerChernoussova)

Eostaffellina sp.

E. paraprotvae (Rauzer-Chernoussova)

Globivalvulina sp.

Lipinella sp. (nom. nud.)

Millerella sp.

Neoarchaediscus sp.

cf. Palaeonubeculariat sp.

Pseudoendothyra sp.

Pseudoglomospira sp.

Volvotextiilaria sp.

Collection 67. Ranchester Limestone Member, Amsden Creek 

locality. 

Age. Zone 20, late Namurian (Reticuloceras Zone), lennsylvanian (Morrowan).

Foraminifers present.

Asteroarchaediscus sp.

A. baschkiricus (Krestovnikov and Teodorovitch)

Biseriella moderata (Reitlinger)

B. parva (Chernysheva)
BIO THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING

Diplosphaerina sp.

Earlandia sp.

Endothyra sp.

Eostaffella sp.

Eotuberitina sp.

Globivalvulina sp.

Globoendothyra sp.

Lipinella sp. (nom. nud.)

Neoarchaediscus sp.

cf. Palaeonubeculariat sp.

Palaeotextularia of the group P. consobrina Lipina

Palaeotextularia of the group P. longiseptata Lipina

Tuberitina sp.

Collection 68. Ranchester Limestone Member, Amsden Creek 

locality. 

Age. Zone 20, late Namurian (Reticuloceras Zone), Pennsylvanian (Morrowan).

Foraminifers abundant.

Apterrinellidae

Archaediscus sp.

Asteroarchaediscus baschkiricus (Krestovnikov and 

Teodorovitch)

Biseriella sp.

Biseriella of the group B. parva (Chernysheva)

B. moderata (Reitlinger)

Caldsphaera sp.

Climacammina sp.

Cornuspiridae

Endothyra sp.

Eostaffella sp.

Eostaffellina paraprotvae (Rauzer-Chernoussova)

Eotuberitina sp.

Globivalvulina sp.

Lipinella sp. (nom. nud.)

cf. Millerellal sp.

Neoarchaediscus of the group N. incertus (Grozdilova 

and Lebedeva)

Neoarchaediscus of the group N. parvus (RauzerChernoussova)

Palaeotextularia of the group P. consobrina Lipina

Palaeotextularia of the group P. longiseptata Lipina

Planospirodiscus sp.

Pseudoglomospira sp.

Stacheiinae

Tetrataxis sp.

Zellerina sp.

Collection 71. Ranchester Limestone Member, Tip Top Well 

locality. 

Age. Zone 21, early Westphalian, Pennsylvanian

(Atokan).

Foraminifers present.

The following list was compiled by Betty Skipp (written 

commun., 1969).

Asteroarchaediscus sp.

Brady mat sp.

Climacammina sp.

Endothyra sp.

Eostaffella sp.

Eostaffella of the group E. acutissima Kireeva

Eostaffellmat sp.

Globoendothyra sp.

Lipinella sp. (nom. nud.)

Millerella sp.

Palaeotextularia of the group P. consobrina Lipina 

Palaeotextularia of the group P. longiseptatz Lipina 

Pseudoglomospiral sp. 

Stacheia sp. 

Stacheoides sp. 

"Trepeilopsis" sp. 

Tuberitina sp.

Collection 74. Moffat Trail Limestone Member, Moffat Trail 

locality.

Age. Zone 18, late early Namurian (upper Eumorphoceras 

Zone), Late Mississippian (Chesterian). 

Foraminifers present. 

Archaediscus sp.

Archaediscus of the group A. krestovnikovi RauzerChernoussova 

Asteroarchaediscus sp.

A. baschkiricus (Krestovnikov and Teodorovitch) 

Biseriella parva (Chernysheva) 

B. moderata (Reitlinger) 

Caldsphaera sp. 

C. laevis Williamson 

Earlandia clavatula (Howchin) 

E. elegans (Rauzer-Chernoussova) 

Endothyra sp. 

Endothyra of the group E. boivmani Phillips emend.

Brady 

Endothyra of the group E. similis Rauzer-Oernoussova

and Reitlinger 

E. excellens (Zeller) 

Eostaffella sp. 

E. circuli (Thompson) 

Endothyranella sp. 

Eotuberitina sp.

Neoarchaediscus incertus (Grozdilova and Lebedeva) 

N. parvus (Rauzer-Chernoussova) 

Palaeotextularia sp. 

Planospirodiscus sp. 

Pseudoendothyra sp. 

Pseudoendothyra of the group P. kremcnskvusis

Rozovskaia

Zellerina discoidea (Girty)

Collection 75. Moffat Trail Limestone Member Moffat Trail 

locality. 

Age. Zone 17 or 18, early Namurian (Eumorphoceras

Zone), Late Mississippian (Chesterian). 

Foraminifers present. 

Archaediscus sp.

Archaediscus of the group A. krestovnikovi RauzerChernoussova 

Asteroarchaediscus sp. 

Caldsphaera sp. 

Endothyra sp. 

Endothyra of the group E. bowmani Phillip^ emend.

Brady

Eostaffella circuli (Thompson) 

Neoarchaediscus sp. 

Pseudoendothyra sp. 

Pseudoendothyra of the group P. kremenskinsis

Rozovskaia

Collection 77. Moffat Trail Limestone Member, Moffat Trail 

locality.

Age. Zone 18, early Namurian, Late Mississippian (late 

Chesterian).
CARBONIFEROUS FORAMINIFERA AND ALGAE

Foraminifers scarce.

Archaediscus sp.

Asteroarchaediscus sp.

Earlandia sp.

Endothyra sp.

Endothyra of the group E. bowmani Phillips emend. 

Brady

Pseudoendothyra sp.

Zellerina sp.

Collection 78. Moffat Trail Limestone Member, Moffat Trail 

locality. 

Age. Zone 18, early Namurian, Late Mississippian (late

Chesterian).

Foraminifers scarce.

Archaediscus sp.

Asteroarchaediscus sp.

Calcisphaera sp.

"Cornuspira" sp.

Endothyra of the group E. bowmani Phillips emend. 

Brady

Eostaffellina sp.

Pseudoendothyra sp.

Zellerina sp.

Collection 79. Moffat Trail Limestone Member, Moffat Trail 

locality. 

Age. Zone 17 or younger, early Namurian (Eumorphoceras Zone) ?, Late Mississippian (Chesterian) ?

Foraminifers present.

Archaediscus of the group A. krestovnikovi RauzerChernoussova

Asteroarchaediscus sp.

Calcisphaera sp.

Endothyra sp.

Eostaffella sp.

E. circuli (Thompson)

Neoarchaediscus sp.

Pseudoendothyra sp.

Pseudoendothyra of the group P. kremenskensis 

Rozovskaia

Pseudoendothyra of the group P. ovata (Reitlinger)

Pseudoendothyra of the group P. struvei (von Moller)

Collection 82. Ranchester Limestone Member, Moffat Trail 

locality. 

Age. Undetermined.

Foraminifers very scarce.

Calcisphaera sp.

Endothyra sp.

Collection 90. Moffat Trail Limestone Member, Covey Cutoff 

locality. 

Age. Zone 17 or 18, early Namurian (Eumorphoceras

Zone), Late Mississippian (Chesterian).

Foraminifers abundant.

Archaediscus sp.

A. krestovnikovi Rauzer-Chernoussova

Asteroarchaediscus sp.

A. baschkiricus (Krestovnikov and Teodorovitch)

Calcisphaera sp.

Climacammina sp.

"Cornuspira" sp.

Diplosphaerina sp.

Earlandia clavatula (Howchin)

E. elegans (Rauzer-Chernoussova)

Endothyra sp.

Endothyra of the group E. boivmani Phillips emend.

Brady 

Endothyra of the group E. similis Rauzer-Chernoussova

and Reitlinger 

Eostaffella sp. 

E. circuli (Thompson) 

Eotuberitina sp. 

Globoendothyra sp.

Neoarchaediscus incertus (Grozdilova and Lebedeva) 

N. parvus (Rauzer-Chernoussva) 

Palaeotextularia of the group P. consobrina Lipina 

Palaeotextularia of the group P. longiseptata Lipina 

Pseudoendothyra sp. 

Pseudoendothyra of the group P. kremenskensis

Rozovskaia 

Stacheoides sp. 

Tuberitina sp. 

Zellerina discoidea (Girty)

Collection 92. Moffat Trail Limestone Member, Covey Cutoff 

locality.

Age. Zone 17 or 18, early Namurian (Eumorphoc°ras 

Zone). Late Mississippian (Chesterian). 

Foraminifers abundant. 

Archaediscus sp. 

Asteroarchaediscus sp.

A. baschkiricus (Krestovnikov and Teodorovitch) 

Calcisphaera sp. 

C. laevis Williamson 

Climacammina sp. 

Diplosphaerina sp. 

Earlandia sp. 

E. clavatula (Howchin) 

E. elegans (Rauzer-Chernoussova) 

Endothyra sp. 

Endothyra of the group E. bowmani Phillips emend.

Brady

E. excellent (Zeller) 

Endothyra of the group E. similis Rauzer-Chernousso-ra

and Reitlinger 

E. tantala (Zeller) 

Eostaffella sp. 

E. circuli (Thompson) 

Eotuberitina sp. 

Neoarchaediscus sp. 

N. incertus (Grozdilova and Lebedeva) 

N. parvus (Rauzer-Chernoussova) 

Palaeoteytularia of the group P. consobrina Lipina 

Palaeotextularia of the group P. longiseptata Lipina 

Planospirodiscus sp. 

P. minimus (Grozdilova and Lebedeva) 

Pseudoendothyra sp. 

Pseudoendothyra of the group P. kremenskensis

Rozovskaia 

Pseudoglomospira sp. 

Tetrataxis sp. 

Tuberitina sp. 

Zellerina discoidea (Girty)

Collection 93. Moffat Trail Limestone Member, Covey Cutoff 

locality.

Age. Zone 17 or 18, early Namurian (Eumorphoceras 

Zone), Late Mississippian (Chesterian). 

Archaediscus sp. 

Asteroarchaediscus sp.
B12 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING

cf. Biseriellal sp. 

Calcisphaera sp. 

Earlandia sp. 

Endothyra sp. 

Eostaffella sp. 

Neoarchaediscus sp. 

Planospirodiscus sp. 

Pseudoendothyra sp. 

Tetrataxis sp.

Collection 100. Ranchester Limestone Member Covey Cutoff 

locality.

Age. Zone 20, late Namurian (Reticuloceras Zone), Pennsylvanian (Morrowan). 

Foraminifers abundant. 

Archaediscus sp. 

Asteroarchaediscus sp.

Biseriella of the group B, parva (Chernysheva) 

B. moderata (Reitlinger) 

Calcisphaera sp. 

Endothyra of the group E. bowmani Phillips emend.

Brady

E. excellens (Zeller) 

"Endothyra" of the group "E." prisca RauzerChernoussova and Reitlinger 

Endothyra of the group E. similis Rauzer-Chernoussova

and Reitlinger 

cf. Eolasiodiscust sp. 

Eostaffella sp. 

Globivalvulina sp. 

Lipinella sp. (nom. nud.) 

Millerella sp. 

M. pressa Thompson 

Monotaxinoides sp. 

Neoarchaediscus sp. 

Planoendothyra sp. 

Planospirodiscus sp. 

Pseudoendothyra sp. 

Pseudoglomospira sp.

Zeller in a sp.

Collection 103. Moffat Trail Limestone Member, Haystack 

Peak locality. 

Age. Zone 17, earliest Namurian (lower Eumorphoceras

Zone), Late Mississippian (middle Chesterian).

Foraminifers scarce.

Archaediscus sp.

Asteroarchaediscus sp.

Calcisphaera sp.

C. laevis Williamson

Earlandia sp.

Endothyra sp.

Neoarchaediscus sp.

Planospirodiscus sp.

Collection 104. Moffat Trail Limestone Member, Haystack 

Peak locality. 

Age. Zone 17, earliest Namurian (lower Eumorphoceras

Zone), Late Mississippian (middle Chesterian).

Foraminifers present.

Archaediscus sp.

Asteroarchaediscus sp.

Calcisphaera laevis Williamson

C, pachysphaerica (Pronina)

Earlandia sp.

Endothyra sp.

Endothyra of the group E. bowmani Phillips emend.

Brady 

Endothyra of the group E. similis Rauzer-Chernoussova

and Reitlinger 

Eostaffella sp. 

E. circuli (Thompson) 

Neoarchaediscus sp.

Palaeotextularia of the group P. consobrina Lipina 

Palaeotextularia of the group P. longiseptata Lipina 

Pseiidoendothyra sp. 

Pseudoendothyra of the group P. kremenskensis

Rozovskaia 

Stacheia sp. 

Stacheoides sp.

Collection 105. Moffat Trail Limestone Member, Haystack 

Peak locality.

Age. Zone 18, late early Namurian (upp-jr Eumorphoceras Zone), Late Mississippian (Chesterian). 

Foraminifers present. 

Archaediscus sp. 

Asteroarchaediscus sp. 

Calcisphaera laevis Williamson 

Climacammina sp. 

Earlandia sp.

E. elegans (Rauzer-Chernoussova) 

Endothyra sp. 

Endothyra of the group E. bowmani Phillips emend.

Brady 

Endothyra of the group E. similis Rauzer-Chernoussova

and Reitlinger 

Eostaffella sp. 

E. pinguis (Thompson) 

Eostaffellina sp. 

Neoarchaediscus sp.

Palaeotextularia of the group P. consobrinc1 Lipina 

Palaeotextularia of the group P. longiseptata Lipina 

Pseudoendothyra sp. 

Pseudoendothyra of the group P. kremenskensis

Rozovskaia

Zellerina discoidea (Girty)

Collection 109. Moffat Trail Limestone Member, South Indian Creek locality.

Age. Zone 17, earliest Namurian (lower Eumorphoceras 

Zones), Late Mississippian (Chesterian). 

Foraminifers abundant. 

Archaediscus sp.

A. krestovnikovi Rauzer-Chernoussova 

Asteroarchaediscus sp.

A. baschkiricus (Krestovnikov and Teodorovitch) 

Earlandia sp. 

E. clavatula (Howchin)

E. vulgaris (Rauzer-Chernoussova and Reitlinger) 

Endothyra sp. 

Endothyra of the group E. bowmani Phillips emend.

Brady 

Endothyra of the group E. similis Rauzer-Chernoussova

and Reitlinger 

Eostaffella sp. 

Globoendothyra sp. 

Neoarchaediscus sp. 

N. incertus (Grozdilova and Lebedeva) 

N. parvus (Rauzer-Chernoussova) 

Planospirodiscus sp.
CARBONIFEROUS FORAMINIFERA AND ALGAE P13

P. minimus (Grozdilova and Lebedeva)

Pseudoendothyra sp.

Zellerina discoidea (Girty)

Collection 121. Moffat Trail Limestone Member, Hoback 

Canyon locality. 

Age. Undetermined.

Foraminifers scarce, occur as ghosts.

Archaediscidae?

Endothyridae?

Eostaffellidae?

Collection 122. Moffat Trail Limestone Member, Hoback 

Canyon locality . 

Age. Zone 18, late early Namurian (upper Eumorphoceras Zone), Late Mississippian (Chesterian).

Foraminifers scarce.

Archaediscus sp.

Archaediscus of the group A. chernoussovensis Mamel

Archaediscus of the group A. krestovnikovi RauzerChernoussova

Asteroarchaediscus sp.

A. baschkiricus (Krestovnikov and Teodorovitch)

Biseriella sp.

B. parva (Chemysheva)

B. moderata (Reitlinger)

Calcisphaera sp.

"Cornuspira" sp.

Earlandia sp.

Endothyra sp.

Eostaffella sp.

Neoarchaediscus sp.

N. incertus (Grozdilova and Lebedeva)

N. parvus (Rauzer-Chernoussova)

Planospirodiscus sp.

Zellerina discoidea (Girty)

Collection 124. Moffat Trail Limestone Member, Hoback 

Canyon locality. 

Age. Zone 18, early Namurian (Eumorphoceras Zone),

Late Mississippian (late Chesterian).

Foraminifers present.

Archaediscus of the group A. krestovnikovi RauzerChernoussova

Asteroarchaediscus sp.

Asteroarchaediscus of the group A. baschkiricus 

(Krestovnikov and Teodorovitch)

Biseriella of the group B. parva (Chernysheva)

B. moderata (Reitlinger)

Calcisphaera sp.

Cornuspiridae

Endothyra sp.

cf. EndostaffeUat sp.

Neoarchaediscus sp.

Planospirodiscus sp.

"Tetrataxis" of the group "T." eominima RauzerChernoussova

Trepeilopsis sp.

Zellerina discoidea (Girty)

Collection 125. Moffat Trail Limestone Member, Hoback 

Canyon locality.

Age. Zone 18 (or younger?), early Namurian 

(Eumorphoceras Zone), Late Mississippian (late

Chesterian).

Foraminifers scarce.

Apterrinellidae

Asteroarchaediscus sp.

Biseriella sp.

B. moderata (Reitlinger)

Neoarchaediscus sp.

Pseudoglomospira sp.

Collection 126. Moffat Trail Limestone Member, Hoi ack 

Canyon locality. 

Age. Zone 17 or 18, early Namurian (Eumorphocvras

Zone), Late Mississippian (Chesterian).

Foraminifers present.

Archaediscus sp.

A. krestovnikovi Rauzer-Chernoussova

Asteroarchaediscus sp.

A. baschkiricns (Krestovnikov and Teodorovitch)

Earlandia sp.

Endothyra sp.

Endothyra of the group E. bowmani Phillips emend. 

Brady

Eostaffella sp.

Glomospira sp.

Monotaxinoides sp.

Neoarchaediscus sp.

Planospirodiscus sp.

Pseudoglomospira sp.

"Tetrataxis" of the group "T" eominima RauzerChernoussova

Zellerina discoidea (Girty)

Collection 132. Ranchester Limestone Member, Hoback 

Canyon locality. 

Age. Zone 20, late Namurian (Reticuloceras Zones),

Pennsylvanian (Morrowan).

Foraminifers scarce.

Biseriella sp.

Calcisphaera sp.

Earlandia sp.

Endothyra sp.

Globivalvulina of the group G. bulloides (Brady)

Pseudoglomospira sp.

Collection 145. Moffat Trail Limestone Member, Phillips 

Canyon locality . 

Age. Zone 18, late early Namurian (upper Eumorphoceras

Zone), Late Mississippian (Chesterian).

Foraminifers scarce.

Archaediscus sp.

Archaediscus of the group A. krestovnikovi RauzerChernoussova.

Asteroarchaediscus sp.

Biseriella sp.

B. parva (Chernysheva)

B. moderata (Reitlinger)

Calcisphaera sp.

Earlandia sp.

Endothyra sp.

Neoarchaediscus sp.

Planospirodiscus sp.

Pseudoglomospira sp.

Tuberitina sp.

Collection 153. Horseshoe Shale Member, Berry Creek 

locality. 

Age. Zone 19, middle Namurian (Homoceras Zone), Late

Mississippian (latest Chesterian).

Foraminifers scarce.

Apterrinellidae
B14 THE AMSDEN FORMATION (MISSISSIPPIN AND PENNSYLVANIAN) OF WYOMING

Archaediscus sp.

Asteroarchaedisciis sp.

Cornuspiridae

"Eosigmoilina" sp.

Eostaffella sp.

Neoarchaediscus sp.

Collection 154. Horseshoe Shale Member, Berry Creek locality. 

Age. Zone 18 or younger, early Namurian (Eumorphoceras Zone) ?, Late Mississippian (Chesterian) ?

Foraminifers scarce.

Apterrinellidae

Cornuspiridae

Biseriella of the group B. parva (Chernysheva) 

Collection 160. Ranchester Limestone Member, Elk Ridge 

locality. 

Age. Zone 18 or younger, early Namurian (Eumorphoceras Zone) ?, Late Mississippian (Chesterian) ?

Foraminifers scarce.

Apterrinellidae

Aster oarchaediscus sp.

Biseriella of the group B. parva (Chernysheva)

Climacammina sp.

Cornuspiridae

Earlandia sp.

Endothyra sp.

E. excellens (Zeller)

Eostaffella sp.

Palaeotextularia sp.

Planospirodiscus sp.

REFERENCES CITED

Armstrong, A. K., Mamet, B. L., and Dutro, J. T., Jr., 1970, 

Foraminiferal zonation and carbonate facies of Carboniferous (Mississippian and Pennsylvanian) Lisburne 

Group, central and eastern Brooks Range, Arctic Alaska: 

Am. Assoc. Petroleum Geologists Bull., vol. 54, no. 5, 

p. 687-698.

 1971, Lisburne Group, Cape Lewis-Niak Creek, Northwestern Alaska: U.S. Geol. Survey, Prof. Paper 750-B, 

p. B23-34.

Bamber. E. W., and Waterhouse, J. B., 1971, Carboniferous 

and Permian stratigraphy and paleontology, northern 

Yukon Territory, Canada: Bull. Canadian Petroleum 

Geology, v. 19, no. 1, p. 29-250. Appendix I, by Mamet, 

B., and Ross, C. A. Foraminiferal microfacies of the 

Upper Paleozoic, northern Yukon Territory, p. 196-205.

Brazhnikova, N. E., Vakarchuk, G. I., Vdovenko, M. V., 

Viniitchenko, L. V., Karpova, M. A., Polomietz, la, I, 

Potievskaia, P. D., Rostovceva, L. F. and Chevtchentko, 

G. D., 1967, Microfaunal reference horizons of the Carboniferous and Permian deposits of the Dnieper-Donets 

basin [in Russian.] Kiev, Izdat. "Naukova Dumka," 224p.

Brenckle, P. L., 1973, Smaller Mississippian and Lower Pennsylvanian calcareous f oraminif ers from Nevada: Cushman Foundation Foraminiferal research, Special Publ. 

no. II, 82p.

Cooper, C. L., 1946, Upper Kinkaid (Mississippian) microfauna [abs.]: Am. Assoc. Petroleum Geologists Joint 

Ann. Meeting Program, April 2-4.

 1947, Upper Kinkaid (Mississippian) microfauna 

from Johnson County, Illinois: Jour. Paleontology, v. 

21, no. 2, p. 81-94.

Easton, W. H., 1962, Carboniferous formation* and faunas

of central Montana. U.S. Geol. Survey, Prof. Paper 348,

p. 1-126, 14 pis. 

Henbest, L. G., 1946, The Morrow Group, I ennsylvanian,

of Washington County, Arkansas [abs.]: Am. Assoc.

Petroleum Geologists Joint Ann. Meeting Program,

April 2-4.

1947, The Morrow Group of northwest Arkansas

[abs.] : Washington Acad. Sci. Jour., v. 37, no. 10, p. 373.

Lane, R. H., Sanderson, G. A. and Verville, G. J., 1972, Uppermost Mississippian-basal Middle Pennsylvanian conodonts and fusulinids from several exposurer in the southcentral and southwestern United States. 24th International Geological Congress, section 7, Paleontology, p. 

549-555.

Loeblich, A. R., Jr., and Tappan, Helen, 1964, Treatise on 

invertebrate paleontology, Part C, Protista 2, Sarcodina, 

chiefly "Thecamoebians" and Foraminiferid": New York, 

Geol. Soc. America and Univ. Kansas P"ess, v. 1, p. 

Cl-C510a; v. 2, p. C511-C900.

Mamet, B. L., 1968, Foraminifera, Etherington Formation 

(Carboniferous), Alberta, Canada: Canadian Assoc. 

Petroleum Geologists Bull., v. 16, no. 2, p. 167-179.

1970, Carbonate microfacies of the Windsor Group

(Carboniferous), Nova Scotia and New Brunswick: 

Canada, Geol. Survey Paper 70-21, p. 1-121, 19 pis.

Mamet, B. L., and Gabrielse, H., 1969, Foraminiferal zonation and stratigraphy of the type section of the Nizi 

Formation (Carboniferous systems, Chesterian Stage), 

British Columbia: Canada Geol. Survey Paper 69-16, p. 

1-21.

Mamet, B. L., and Mason, D., 1970, Lisburne Group; lithostratigraphy and f oraminiferal zonation, Trout Lake, 

northwest Yukon Territory. Bull. Canadian Petroleum 

Geology, v. 18, no. 4, p. 556-565.

Mamet B. L., and Skipp, B. A., 1970, Preliminary foraminiferal correlations of early Carboniferous strata in the 

North American Cordillera, in Cong. et Cclloques, Colloque sur la stratigraphie du Carbonifere: Liege Univ. 

v. 55, p. 327-348.

Mamet, B. L., Skipp, Betty, Sando, W. J., ard Mapel, W., 

1971, Biostratigraphy of Upper Mississippan and associated Carboniferous rocks in south-centrrl Idaho: Am. 

Assoc. Petroleum Geologists Bull., v. 55, ni. 1, p. 20-33.

Mellen, F. F., 1947, Black Warrior Basin, Alabama and 

Mississippi: Am. Assoc. Petroleum Geologists Bull., v. 

31, no. 10, p. 1801-1816.

Moore, W. L., 1964, Notes on the morphology and taxonomic 

position of the fusulinid MiUerella marbJensis Thompson: Jour. Paleontology, v. 38, no. 2, p. 294-305.

Sage, N. M., Jr., 1954, The stratigraphy of the Windsor 

Group in the Antigonish quadrangles and the Mahone 

Bay-St. Margaret Bay area, Nova Scotia: Nova Scotia 

Dept. Mines Mem., no. 3, 168 p.

Sando, W. J., Gordon. Mackenzie, Jr., and Dutro, J. T., Jr., 

1974, Stratigraphy and geologic history of the Amsden 

Formation (Mississippian and Pennsylvanian) of Wyoming: U.S. Geol. Survey Prof. Paper 848-A (in press).

Sando, W. J., Mamet, B. L. and Dutro, J. T., Jr., 1969, Carboniferous megafaunal and microfaunal zonation in the 

northern Cordillera of the United States: U.S. Geol. 

Survey Prof. Paper 613-E, 29p.

Scott, H. W., 1945a, Age of the Amsden Formation [abs.]: 

Geol. Soc. America Bull., v. 56, no. 12, pt. 2, p. 1195.
CARBONIFEROUS FORAMINIFERA AND ALGAE P15

 1945b, Pennsylvania!! stratigraphy in Montana and 

and northern Wyoming [abs.]: Geol. Soc. America Bull., 

v. 56, no. 12. pt. 2, p. 1196.

Skipp, B. A. and Mamet, B. L., 1970, Stratigraphic micropaleontology of the type locality of the White Knob 

Limestone (Mississippian), Custer County, Idaho: U.S. 

Geol. Survey, Prof. Paper 700-B, p. B118-B123.

Thompson, M. L., 1942, New genera of Pennsylvanian fusulinids: Am. Jour. Sci., v. 240, no. 6, p. 403-420.

 1944, Pennsylvanian Morrowan rocks and fusulinids 

of Kansas: Kansas Geol. Survey Bull. 52, pt. 7, p. 409- 

431.

 1945, Pennsylvanian rocks and fusulinids of east 

Utah and northwest Colorado correlated with Kansas 

section: Kansas Univ. Geol. Survey Bull. 60, pt. 2, p 

17-84.

 1948, Studies of American fusulinids: Kansas Univ.

Paleont. Contr., Protozoa, art, 1, p. 1-134.

Zeller, D. E. N., 1953, Endothyroid Foraminifera and ancestral fusulinids from the type Chesterian (Upper Mississippian). Jour. Paleontology, v. 27, no. 2, p. 183-19r>.

Zeller E. J., 1950, Stratigraphic significance of Mississippian 

endothyroid Foraminifera: Kansas Univ., Paleont. 

Protozoa, art. 4, 23 p.

INDEX

Page

Adetognathus gigantus -____--_-_--_-_ B7

lautus _ .-. .- ----- 7

Alapah Limestone --. . .-- 6, 6 

Amsden Creek locality, Ranchester

Limestone Member, Zone 

20, Morrowan ___ 6, 9, 10; pi. 2, 

figs. 4-6, 7, 8

Apterrinellidae ___.._ __ 7, 8, 9, 10, 13, 14 

Archaediscidae ________________ 2, 7, 13 

Archaediscus ... .. 2

chernotiaaovensis ______________ 1, 2, 13

krestovnikovi ...... 1, 2, 8, 9, 10, 11, 12, 13

moetteri .._ - . ___.__--_._ 2

sp ___________ 1,7,8,9,11,12,13,14

Asphaltina ... _ _ 2,7,8

Aateroarchaediscus _-_._________ 2, 4, 6

baschkiricus ........ 1, 4, 5, 7, 8, 9,10, 11,

12, 13; pi. 2, fig. 1 

sp _________ 1, 7, 8, 9, 10,11, 12, 13,14

B

Baschkirian-Moscovian succession.

correlation problems ----- 6

Battleship Wash Formation __.__._ B 

Berry Creek locality, Harseshoe Shale 

Member, Zones 18 and 19, 

Chesterian _ ----- 5, 6, 13, 14

Biostfatigraphic indices, list of useful

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

relict forms --. ---_.-----__ 3,4,6

Biostratigraphic zonation .-_.-_.. 4 

Bird Spring Formation .. _.__ 6, 7 

Biseriamminidae _-----___-_-_-____ 2

Biseriella ............ ----- 4, 6, 6

moderata ............ 1,7,8,9,10,12,13;

pi. 2, fig. 4-6 

parva ............... 2, 5, 9, 10, 12, 13, 14

sp ____________ 1,7,8,9,10,12,13;

pi. 2, flgs.2, 4-6

Bradyinal ............................ 3

sp ________ ___ _____ 2, 10 

Bradyinidae 3 

Brunsia ......................... -__ 3

Buck Spring locality, Ranchester

Limestone Member, Zone

20, Morrowan-- 6, 8; pi. 2, figs. 2, 3

Ccdcisphaera laevis ........... 2,8,10,11,12;

pi. 1, figs. 1, 2 

pachyaphaerica ......._________ 12

sp _____________ 7,8,9,110,11,12,13;

pi. 2, figs. 4-6

Calico Bluff Formation __--------- 5

Cherokee Spring and Peak localities, 

Horseshoe Shale Member, 

Zone 20, Morrowan __ 6, 7, 8 

Climacammina ......--------------___ 4

sp ____ 2, 9, 10, 11, 12, 14; pi. 1, figs. 1, 2 

Clore Limestone -.___- -... 6 

Cornuspira ------ -------- - 3

sp _________________ 2,7,8,11,13

[Italic numbers indicate major references]

Page

Cornuspiridae (sensu lato) .. 63,9,10,13,14 

Covey Cutoff locality, Moffat Trail

Limestone Member, Zone 17 

or 18, Chesterian___ 6, 11; pi. 1, 

figs. 1, 2 

Ranchester Limestone Member, Zone

20, Morrowan________._ 6, 12; 

pi. 1, figs. 6-8

D

Darwin Sandstone Members, no fauna

collections from .-____-- 1 

Diplosphaerina sp _-_____ 2, 7, 8, 9, 10, 11 

Donbass sequence __.________________ 6

E

Earlandia ..................____..-. 3

clavatula _____________ 2, 10, 11, 12 

elegans _ .________ 2,10,11,12

vuloarte ........................... 2,12

sp _________ 2, 7, 8, 9, 10, 11, 12, 13, 14; 

pi. 1, figs. 6-8

Earlandiidae ___..____.._._ 3 

Elk Ridge locality, Ranchester Limestone 

Member, Zone 18 or 19, 

Chesterian ________ 5,6,14 

EndostaffelM ...-____________ 3 

sp ______________________ 2,13 

Endothyra -_-__-.-._..__.-._____ 3 

bowmani ____ __ 2, 8, 9, 10, 11, 12, 13;

pi. 1, figs. 1, 2, 3, 6-8

excellens __________ 2,10,11,12,14;

pi. 1, figs. 1, 2, 6-8

prisca ...._ . 2, 8, 12; pi. 1, figs. 6-8

similia _______________ 2, 10, 11, 12 

tantala ...____________ 11

sp ________ 2, 7, 8, 9, 10, 11, 12, 13, 14;

pi. 1, figs. 1, 2; pi. 2, figs. 4-6

Endothyranetta sp _---.-.__------- 2, 7, 10

Endothyranopsidae - .. __ -_ 4, 5 

Endothyranopsis sphaerica ____________ 6

Endothyridae _________________ 3,13

Eolasiodiscus ____-_--_____-_._____... 3

sp ________.____________ 2,12 

Eoschubertella ... -_____---_.____._ 3, 6

sp -._ _.__ ___-. 2, 8 

EosigmoUina . __.-__________________ 2, 6

sp ___________.________ 2, 14 

Eostaffetta ___________________._____ 3, 7

acutissima ______________________ 2, 10

circuli ... . .. 2,9,10,11,12;

pi. 2, figs. 4-6, 8

pinguis --------..-._-- .-._ 2, 12

pseudostruvei --------- 2, 9; pi. 2, figs. 4-6

sp _________ 2, 7, 8, 9, 10, 11, 12, 13, 14;

pi. 2, figs. 1, 4-6, 8

Eostaffellidae __.._______.- 3,7,13

Eostaffellina -------------------------- 3, 5

paraprotvae ------- 2, 9, 10; pi. 2, figs. 4-6

sp ___.__.______ 2.8,9,10,11,12 

Eotuberitina sp __..____.. 2, 7, 8, 9, 10, 11;

pi. 2, figs. 2, 3 

Etherington Formation -..--_-----._-- 5

Pige 

Ettrain Formation ------.. -- B6

Eumorphoceras Zone ___._-_ 9, 10, 11, 12, 13 

Evolutionary changes of wall structure 2, 6

Fusulinidae

Gvrvanella sp 7

Glen Dean Limestone - --___------- 6

Globivalvulina --_.__ __ 2, 6

buttoides ... ______________ 2,8,13

sp ______ 2, 7, 8, 9, 10, 12; pi. 2, figs. 2, 3

Globoendothyra --.. _ 3

sp ______.________ 2,10,11,12 

Globoendothyridae .-. 3

Glomospira sp ----_ .-_-. 2, 13

Golconda Formation - __. --- 6

H

Hart River Formation ---_--- - 6 

Haystack Peak locality, Moffat Trail

Limestone Member, Zone 17 

and 18, Chesterian ____ 6, 12 

Hoback Canyon locality, Moffat Trail

Limestone Member, Zones 17 

or 18 and 18 and undetermined _ 6, 13 

Ranchester Limestone Member, Zone

20, Morrowan --.- 6, 13 

Homoceras Zone ____---------------- 6, 13

Horseshoe Shale Member ___ 1, 6, 6, 7, 8, 9, 14 

Howchinia __ -_.-_.-- .- 4

Indian Spring Formation ------------ B, 6, 7

K

Kinkaid Limestone ------ ------ 5, 7

Kogruk Formation -_---------------- B

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

Lipinella sp _________-. 2,7,8,9,10,12 

Livingston Ranch locality, Horseshoe

Shale Member, Zone 18, late 

Chesterian . ------- ___ 5, 9

Loeblichia .--_----__-----_------------- B

M

Meadow Ranch locality, Ranchester

Limestone Member, Zone

20, Morrowan __ 6, 8; pi. 2, f «r. 1

Menard Limestone -_._------_--_------ 5

Microfauna distribution, lithologic

controls ------------------- 1, 2

Microfossils, listed by collection number 7

PIT
B18 INDEX

Page

Millerella ......................... B3, 4, 6, 7

generic concept problems _ . 7 

pressa .......................... 2, 8, 12

pura ........ ._ 2, 8

sp ______ 2, 7, 8, 9, 10, 12; pi. 1, figs. 6-8 

Mississippian-Pennsylvanian boundary

problems _ _ 6, 7 

Moffat Trail Limestone Member. _ 1, 5. 10, 11, 

12,13; pi. 1, figs. 1-5 

partial time equivalence(?) to

Horseshoe Shale Member__ 5 

Moffat Trail locality, Moffat Trail

Limestone Member, Zones 17 

or 18 and 18, Chesterian 5, 10, 11; 

pi. 1, figs. 4, 5 

Monotaxinoides ....___-.._____ 4

sp _._________ 2, 12, 13; pi. 1, figs. 6-8 

Monroe Canyon Limestone _________ 5

N

Neoarchaediscus ...................... 2,4,5

incertus ........... 2, 7, 8, 9, 10, 11, 12, 13

parvus ................. 2,7,8,10,12,13

sp ___________ 2, 8, 9, 10, 11, 12, 13, 14

Nizi Formation . _ 5, 6

O

Ozawainellidae 4, 7

PalaeonubecularM sp .. _. 2, 9, 10 

Palaeotextularia __________________ 4

consobrlna ................... 2,10,11,12

longiaeptata .......______ 2, 10, 11, 12

sp ____________________ 2,9,10,14 

Palaeotextulariidae ____ _____ 4

Phillips Canyon locality, Moffat Trail

Limestone Member, Zone 18, 

Chesterian _-_--__ 5,13 

Phylogenetic lineages --- - 2 

Planoendothyra -................... 3

sp __________________ 2,8,9,11,12

Page 

Planospirodiacus .................... B2, 4, 5

minimus ....................... 2, 11, 18

sp ________ 2, 7, 8, 9, 10, 11, 12, 13, 14;

pi. 2, fig. 7 

Paeudoendothyra ... ...... 4, 5

kremenskensis .......___ 2, 10,11, 12

ovata ................ 2, 11; pi. 1, fig. 4, 5

struvei ............ 2, 11; pi. 1, figs. 4, 5

sp ____________ 2,7,8,9,10,11,12,13;

pi. 1, figs. 1, 2, 3; pi. 2, figs. 4-6

Pseudoendothyridae ___________ ____ 4

Pseudoglomospira sp __ 2, 7, 8, 9, 10, 11, 12, 13 

Pseudostaffella ................ ____ 6

Q

^uasiarchaediseus ......_____ _____ 2,5,6

R

Banchester Limestone Member -- 1, 5, 6, 8, 9, 

10, 11, 12, 13, 14; pi. 1, figs. 6-8; pi. 2, figs. 1-8 

partial time equivalence(?) to

Horseshoe Shale Member__ 7, 8 

Rawlins US 287 locality, Ranchester

Limestone Member, Zone 21,

Atokan -__._-_ . 6, 8

References cited 14

Beticuloceras Zone ____.___ 7,8,9,12,13

Rhodophycophyta __ --- 2, 8

Semistaffella .......................... 6

South Indian Creek locality, Moffat Trail 

Limestone Member, Zone 17, 

Chesterian ___ 5, 12; pi. 1, fig. 3 

Spongioatromata ............ -____. 2

Stacheia ............____.. ___ 2,10,12

Stacheiinae ______-_-___ - _-_.. 9,10 

Stacheoides ...................... 2, I'D, 11, 12

Stratigraphic position of fossil collections

in sections _____________ 1

Surrett Canyon Formation ___ 5, 6

Page

Taxonomic composition of Amsden

faunules, by families ____ B2 

Tethyan realm indices .----____-_ 4,5,6 

Tetrataxidae 4

Tetrataxis ..._____-_.____-___-____ 4

eominima .............. 2, 13

sp _______________ 2,8,9,10,11,12 

Tip Top Well locality, Ranchest«r Limestone Member, Zone 21, 

Atokan __________ 3,6,10 

Trepettopais sp ______________ 2, 10, 13 

Trout Creek locality, Rancheste~ Limestone Member, Zore 20(7), 

Morrowan(?) _______ 6, 9 

Tuberitina sp _ -___ 2, 9, 10, 11, 13 

Turrispiroides sp pi. 1, figs. 6-8

Valvulinella .......................... 4

Volvotextularia sp _________ 2, 9

W

Wahoo Limestone .___. 

White Knob Limestone 

Williston basin ____. 

Windsor Group ..

Zellerina ............................. 3, 7

discoidea .............. 2, 9, 10, 11, 12, 13

sp __________-____ 2,7,8,10,11,12; 

El. 1, figs. 1, 2, 6-8

Zone 168 -__ -_._ _ ._.__.__ 4 

Zone 17 -__ ____________ 4

Zoue 18 ____ -.____ ____.__ 5 

Zone 19 -__ _____________ 6 

Zone 20 ___________________ 6 

Zone 21 _- _ _ . -_ _. 6
PLATES 1 and 2

[Contact photographs of the plates in this report are available, at

cost, from U.S. Geological Survey Library, Federal Center,

Denver, Colorado 80225]
PLATE 1

[All figures X 25, except fig. 8 X 17]

FIGURES 1,2. Collection 92, Covey Cutoff locality, Moffat Trail Limestone Member, Zone 17, earliest Namurian, middle Chester equivalent. Recrystallized foraminiferal-pelmatozoan-lump-bearing grainstone. Forg minif eral wall 

recrystallization is highly variable in figure 1, the diaphanotheca of the Pseudoendothyra sp. is reduced 

to a ghost, whereas the tectum of the nearby Endothyra is perfectly preserved. Biota is composed of 

Endothyra of the group E. bowmani Phillips emend. Brady (Endothyra esccellens of Zeller), Endothyra sp., 

Climacammina sp., Calcisphaera laevis Williamson and minute Zellerina sp.

3. Collection 109, South Indian Creek locality, Moffat Trail Limestone Member, Zone 17, earliest Namurian, 

middle Chester equivalent. Slighty recrystallized wackestone; diverse sections of Endothyra of the group E. 

bowmani Phillips emend. Brady, Earlandia sp., and Pseudoendothyra sp. are recognizable.

4,5. Collection 79, Moffat Trail locality, Moffat Trail Limestone Member, Zone 17 or 18, early Namurian, upper 

Chester equivalent. Slighty dolomitized, recrystallized packstone and grainstone. Foraminifers are almost 

exclusively pseudoendothyrids; Pseudoendothyra of the group P. ovata Eeitlinger, Pseudoendothyra of the 

group P. struvei (von Moller), etc.

6-8. Collection 10, Covey Cutoff locality, Eanchester Limestone Member, Zone 20, late Namurian, basal Pennsylvanian. Slightly recrystallized foraminiferal wackestone-packstone. Numerous equatorial sections of Monotaxinoides sp. are visible. Other taxa are Endothyra of the group E. bowmani Phillips emend. Brady 

(Endothyra excellens of Zeller), Zellerina sp., cf. Millerellal sp., Earlandia sp., Turrispiroides sp., and 

"Endothyra" of the group "E." prisca Rauzer-Chernoussova and Reitlinger.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 848-B PLATE 1

..-.XV^^BK^bc* '- - .- v-n'.iLri'

REPRESENTATIVE THIN SECTIONS OF FORAMINIFERS AND 

ALGAE FROM THE AMSDEN FORMATION
PLATE 2

[All sections from Ranchester Limestone Member, Zone 20, late Namurian, basal Pennsylvanian]

FIGURE 1. Collection 13, Meadow Ranch locality, X 30. Recrystallized wackestone. A small Asteroarchaediscus of the 

group A. baschkiricus (Krestovnikov and Teodorovitch) is barely visible, right of Eostaffella sp.

2, 3. Collection 14, Buck Spring locality X 30. Foraminiferal-pelmatozoan-spongiostromid pelletoid grainstone. Note 

the abundance of serpulopsids, apterrinellids, and biseriamminids (GloMvalvulina sp., Biseriella sp.). Small 

tuberitinids ("Eotuberitina" sp.) are also present.

4-6. Collection 65, Amsden Creek locality, figs. 4, 5, X 97, fig. 6, X 25. Foraminiferal packstone rich in apterrinellids, 

serpulopsids, and eostaffellids (Eostaffellina paraprotvae (Rauzer-Chernoussova), Eostaffella circuli (Thompson), deeply umbilicated Eostaffella of the group E. pseudostruvei (Rauzer-Chernoussova), Eostaffella sp.). Some 

Endothyra sp., Pseudoendothyra sp., Biseriella moderata (Reitlinger), Biseriella sp., and Calcisphaera sp. 

are also present. The high magnification photographs show the wall structure of Biseriella sp. (a dark, dense 

tectum) and of Eostaffellina paraprotvae (Rauzer-Chernoussova).

7. Collection 68, Amsden Creek locality, X 30. Recrystallized packstone with a tiny Planospirodiscus sp.

8. Collection 64, Amsden Creek locality, X 25. Pelmatozoan packstone with Eostaffella sp. and Eostaffella circuli 

(Thompson).
GEOLOGICAL SURVEY PROFESSIONAL PAPER 848-B PLATE 2

REPRESENTATIVE THIN SECTIONS OF FORAMINIFERS AND 

ALGAE FROM THE AMSDEN FORMATION

* U.S. GOVERNMENT PRINTING OFFICE: 1975 O S85 473/83