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Xerox University Microfilms aoo Nona ZMb now Ann Arbor, Michigan 40106 76-10,005 MARCANTEL, Emily Laws, 1943- CONODONT BIOSTRATIGRAPHY AND SEDIMENTARY PETROLOGY OF THE GERSTER FORMATION (GUADALUPIAN) IN EAST CENTRAL NEVADA AND WEST CENTRAL UTAH. The Ohio State University, Ph.D., 1975 Geology

Xerox University Microfilms, Ann Arbor. Michigan 48106

THIS DISSERTATION HAS BEEN MICROFILMED EXACTLY AS RECEIVED. CONODONT BIOSTRATIGRAPHY AND SEDIMENTARY PETROLOGY

OF THE GERSTER FORMATION (GUADALUPIAN) IN

EAST CENTRAL NEVADA AND WEST CENTRAL UTAH

DISSERTATION

Presented in Partial Fulfillment of the Requirements for

the Degree Doctor of Philosophy in the Graduate

School of The Ohio State University

By

Emily Laws Marcantel, B.A., M.S,

*******

The Ohio State University

1975

Reading committee: Approved By

Stig M. Bergstrom

James W. Collinson Adviser £ Department of Geology Walter C. Sweet and Mineralogy ACKNOWLEDGMENTS

I wish to express my appreciation to the following

people: Professor James W. Collinson, who served as my

adviser and assisted with field work; Professor Walter C.

Sweet, who stimulated my interest in conodont systematics, and who, with Professor Stig M. Bergstrom, offered valuable

advice and critically read the manuscript; Ms. Mary Baird, who assisted with field work and generously shared infor­ mation from her thesis project on the Kaibab Formation;

Mr. Art W. Browning, Mr. Duncan Foley, Mr. Allen Young, and Mr. Dennis Zlatkin, who assisted in the field work;

Ms. Kit Browning, Mr. Graham Larson, Mr. Jay Spielman, and Mr. Richard Thomas, who assisted with laboratory work;

Mr. Robert Markley, who supervised part of the microphotog­ raphy and use of the scanning electron microscope; and

Mr. Robert Wilkinson, who assisted in part of the micro­ photography and prepared most of the photographs. Profit­ able discussion regarding conodont systematics and related problems was carried on with Mr. John Carnes and Mr. John

Croft at The Ohio State University and with colleagues at

ii other institutions, particularly Ms. Laurel Babcock of

University of Wisconsin, Professor Fred Behnken of Texas

Tech University, Professor William Butler of Russell Sage

College, Dr. Barry Perlmutter of New Jersey State College,

Mr. Bruce Wardlaw of the Smithsonian Institution, and Mr.

Frank Wind of Florida State University. Most importantly,

I wish to thank my husband. Dr. Jon Marcantel of Shell Oil

Company, who assisted me in the field and laboratory, and my children, Mike and Katie, for their patience during com­ pletion of this dissertation.

This study is part of a project involving the Permian and Triassic Systems of the Cordilleran miogeosyncline, which was funded by National Science Foundation Grant

GA-23904. Typing by Miss Kathy Gough and drafting by

Mr. Robert Bartlett for the final copy were generously pro­ vided by Getty Oil Company, Houston, Texas.

iii VITA

April 5, 1943 ...... Born - Colunibus, Ohio

1966...... B.A., The Ohio State University, Columbus, Ohio

1966...... Summer Geologist, Shell Oil Company, New Orleans, Louisiana

1966...... National Science Foundation Trainee, University of Texas, Austin, Texas

1967...... Married - Jonathon Benning Marcantel

1967-1968 ...... Teaching Assistant and chevron Fellow, Louisiana State University, Baton Rouge, Louisiana

1968 ... M.S., Louisiana state University, Baton Rouge, Louisiana

1968-1970 ...... Geologist, United States Geological Survey, Denver, Colorado and Cleveland, Ohio

1970 ...... Son - Michael Ora

1971-1974 ...... Research Assistant, Teaching Assistant and National Science Foundation Fellow, The Ohio State University, Columbus, Ohio

1974...... Daughter - Catherine Amelia

iv 1975 Geologist, Getty Oil Company, Exploration and Production Research Laboratory, Houston, Texas

PAPERS AND PRESENTATIONS

Marcantel, E. L. & Weiss, M. P., 1968, Colton Formation (Eocene, Fluviatile) and Associated Lacustrine Beds, Gunnison Plateau, Central Utah; Ohio Jour. Sci., v. 6 8 , no. 1, pp. 40-49.

Marcantel, E. L., 1968, Paleoecology and Diagenetic Fabrics of a Lower Cretaceous Rudist Reef Complex in West- Central Texas, Louisiana State University, Baton Rouge, Louisiana, 120 p. (unpublished M.S. Thesis)

Marcantel, E. L., 1969, The Skelly-Hobbs Rudist Reef Complex? Lower Cretaceous Shallow-Shelf Carbonates, West Central Texas, Guidebook, Am. Assoc. Petrol. Geol. Annual Meeting, April, 1969, pp. 19-39.

Marcantel, E. L., 1973, Upper Permian Conodont Biostratig­ raphy of northeast Nevada and west central Utah; Geol. Soc. Am., Abstracts with Programs, North-Central Section, v. 5, no. 4, p. 334.

Marcantel, E. L., 1974, Stratigraphy and Conodont Paleon­ tology of the Gerster Formation, Eastern Nevada and Western Utah in Permian and Triassic Biostratigraphy of the Central Cordilleran Miogeosyncline, J. W. Collinson, ed., Ohio State University Research Foun­ dation Final Report, pp. 32-41.

FIELDS OF STUDY

Major Field: Geology

Studies in Carbonate Petrology. Professors Robert L. Folk and Clyde Moore Jr.

Studies in Biostratigraphy and Paleontology. Professors James W. Collinson, Walter C. Sweet, Stig M. Bergstrom and Aurele LaRocque v TABLE OF CONTENTS

Page ACKNOWLEDGMENTS ...... ii

VITA ...... iv

LIST OF TA B LE S ...... viii

LIST OF FIGURES ...... ix

LIST OF PLATES ...... xii

INTRODUCTION ...... 1

Summary of Previous Work ...... 1 Methods of Study ...... 6

Chapter

I. STRATIGRAPHY ...... 9

Regional Setting ...... 9 Stratigraphy of the Gerster and Related Formations ...... 11

II. CONODONT DISTRIBUTION AND BIOSTRATIGRAPHIC FRAMEWORK OF THE GERSTER FORMATION.... 28

III. DEPOSITIGNAL ENVIRONMENT AND CONODONT PALEOECOLOGY ...... 41

IV. THE MONTELLO SECTION ...... 65

V. AGE AND CORRELATION OF THE GERSTER FORMATION 70

A g e ...... 70 Correlations with other Formations . „ 73 Page VI. SYSTEMATIC PALEONTOLOGY ...... 76

Anchignathodus Sweet ...... » . 79 Anchignathodus n. s p ...... 89

Ellisonia Muller ...... 98 Ellisonia n. s p ...... 100

Neoqondolella Bender & Stoppel . . . 117 Neogondolella n. sp ...... 118

Neospathodus Mosher ...... 123 Neospathodus arcucristatus Clark & B e h n k e n ...... 124 Neospathodus dlverqens (Bender & Stoppel) . 128

Xaniognathus Sweet ...... 130 Xaniognathus tribulosus (Clark & E t h i n g t o n ) ...... 133

Unassigned A^? element ...... 145

VII. CONCLUSIONS ...... 147

APPENDICES . 150

A - Measured Sections ...... 150 B - Distribution of conodont elements ..... 161

PLATES ...... 183

BIBLIOGRAPHY ...... 192 LIST OF TABLES

Table Appendix B, Page

1. Conodont element distribution by sample - Butte Mountains ...... 162

2. Conodont element distribution by sample - Cherry Creek Range ...... 163

3. Conodont element distribution by sample - Confusion Range ...... 166

4. Conodont element distribution by sample - Currie Ravine ...... 170

5. Conodont element distribution by sample - Gold H i l l ...... 172

6 . Conodont element distribution by sample - Medicine R a n g e ...... 173

7. Conodont element distribution by sample - Montello ...... 176

8 . Conodont element distribution by sample - Phalen B u t t e ...... 179

9. Conodont element distribution by sample - Southern Pequop Mountains .... 181

viii LIST OF TEXT FIGURES

Page Figure

1. Map of study area showing location of measured sections ...... 7

2. Structural setting ...... 10

3. Paleogeographic framework of the Phosphoria B a s i n ...... 12

4. Isopach map of present-day thickness of the Gerster Formation ...... 17

5. Photomicrograph of sparry brachiopod p a c k s t o n e ...... 20

6 . Photomicrograph of sparry crinoid packstone . . 20

7. Photomicrograph of micritic brachiopod p a c k s t o n e ...... 22

8 . Photomicrograph of fossil fragments in micritic packstone ...... 22

9. Photomicrograph of fossil fragment packstone . 23

10. Photomicrograph of layered brachiopod p a c k s t o n e ...... 23

11. Photomicrograph of crinoid wackestone ...... 24

12. Photomicrograph of brachiopod grainstone . . . 24

13. Photomicrograph of chert replacement in sparry packstone ...... 25

ix Figure Page

14. photomicrograph of selective silicification of fossil grains ...... 25

15. Ranges of conodont species by zones ..... 32

16. East-west cross section of Gerster Formation in Nevada and U t a h ...... 38

17. Southwest-northeast cross section of Gerster and related formations in Nevada ...... 39

18. North-south cross section of Gerster and related formations in Nevada and Utah .... 40

19. l3 opach of Gerster Formation, Zone B ...... 45

20. Hypothetical carbonate depositional model . . 48

21. Block diagram illustrating depositional envi­ ronment during upper Plympton time ...... 51

22. Block diagram illustrating depositional envi­ ronment during lower Gerster t i m e ...... 51

23. Block diagram illustrating depositional envi­ ronment during middle Gerster time ...... 52

24. Block diagram illustrating depositional envi­ ronment during upper Gerster time ...... 52

25. Hypothetical model of upper Plympton and Gerster deposition and subsequent erosion to present condition ...... 53

26. Measured section at Butte Mountains ...... 152

27. Measured section at Cherry Creek ...... 153

28. Measured section at Confusion Range ...... 154

29. Measured section at Currie Ravine ...... 155

30. Measured section at Gold H i l l ...... 156 x Figure Page

31. Measured section at Medicine Range ...... 157

32. Measured section at Montello ...... 158

33. Measured section at Fhalen Butte ...... 159

34. Measured section at Southern Pequop M o u n t a i n s ...... 160 LIST OF PLATES

Page Plate

1. Anchignathodus n. sp. , Ellisonia n. sp. , Neospathodus arcucristatus, Neospathodus divergens, Xaniognathus tribulosus ...... 185

2. Neogondolella n. sp., Neospathodus arcucris­ tatus , Neospathodus divergens ...... 188

3. Unassigned elements, and N elements of Ellisonia, Xaniognathus and Anchiqnathodus . . 191 INTRODUCTION

Summary of Previous Work - The Gerster Formation, consisting of interbedded fossiliferous packstone and wacke stone and silty carbonate or calcareous siltstone, is the youngest Permian formation known from the Cordilleran mio- geosyncline in eastern Nevada and western Utah- Students of regional or upper Paleozoic stratigraphy (Eissell, 1962a

1962b, 1964, 1967, 1969, 1970, 1972; Steele, 1960; Hodgkin- son, 1961; Roberts and others, 1965; Sheldon and others,

1967; Armstrong, 1968b) have frequently mentioned and des­ cribed the Gerster Formation in their papers, but to date no detailed investigations of its iithologic characteris­ tics, depositional environment or fauna have been published

The Gerster Formation contains an abundant brachiopod fauna

Based upon these brachiopods, the age of the Gerster Forma­ tion has been variously given as Wordian (Bissell, 1962b,

1972; Wardlaw, 1974a, 1974b), Wordian to Capitanian (Dunbar and others, I960; Hodgkinson, 1961; Yochelson, 1968) or

Capitanian (Steele, 1960). Clark and Behnken (1971) and

Behnken (1972, 1975a) have described conodonts and established a conodont zonation from sections of the Ger­ ster Formation at Palomino Ridge (Phalen Butte) and the central Butte Mountains, Nevada. Based upon conodonts,

Clark and Behnken (1971), Behnken (1972, 1975a) and Bissell

(1970, 1972, 1974) have assigned a Capitan age to the Ger­ ster Formation.

This investigation expands on the conodont biostrati- graphic framework developed by Clark and Behnken and demon­ strates its utility for regional correlation. The age of the Gerster Formation based on conodonts is shown to be most probably Wordian, supporting the brachiopod age deter­ minations of Wardlaw (1974a, 1974b). Upper Permian deposi­ tional environments are postulated for the study area and their relationship to conodont distribution is discussed.

Permian rocks of the eastern Great Basin have been discussed by several authors. Bissell (1962a, 1962b,

1964), Steele (1960) and Hodgkinson (1961) have catalogued and described the stratigraphy of numerous Permian locali­ ties. Permian paleogeography and the structural evolution of the central Cordilleran miogeosyncline during late Pale­ ozoic time have been described by Roberts and others (1965),

Bissell (1967, 1969, 1970) and Armstrong (1968b). Bissell

(1972, 1974) discussed the Permo-Triassic boundary as exemplified by the Gerster-Thaynes contact in Utah and

Nevada. Permian rocks of the eastern Great Basin were

related to Permian deposits in other parts of the United

States by the paleotectonic summaries of McKee, Oriel, and others (196 7a) and their accompanying paleotectonic maps

(McKee, Oriel and others, 1967b). Published Permian key

sections resampled for this report include Gold Hill (Nolan

1930, 1935), the Confusion Range (Hose and Repenning, 1959)

the Medicine Range (Collinson, 1968) and the southern

Pequop Mountains (Yochelson and Fraser, 1973). The Park

City and Phosphoria Formations, parts of which are lateral

equivalents of the Gerster Formation, have been discussed by MeKeIvey and others (1959). Park city and Phosphoria

faunas have been described by Yochelson (1968).

Clark and Behnken (1971) summarized the published

literature on Permian conodonts up to 1970. Since that time, work on Permian conodonts has been accelerated and

a large number of papers and abstracts have appeared.

Sweet (1970a, 1970b) published the first studies cf Upper

Permian and Lower Triassic conodonts from the Salt Range in

Pakistan and from Kashimer. In these papers, Sweet first established multielement apparatuses that have since served

as models for many late Paleozoic and Triassic conodont workers. Continuing his Permian-Triassic boundary studies,

Sweet (1973a) described possible genetic relationships

among Permian and Triassic conodont groups, and (1973b)

catalogued worldwide conodont faunas across the Permian-

Triassic boundary. In Assereto and others (1973) Sweet

described conodonts from the Permian-Triassic boundary in

the southern Alps and in Teichert, Kummel and Sweet (1973) he did the same for northwestern Iran.

Other North American students described Permian con­

odont faunas from the central and western United States.

Behnken (1972, 1975a) discussed Wolfcampian, Leonardian

and Guadalupian conodonts in Nevada, Idaho, Wyoming, South

Dakota and West Texas. He also (1975b) proposed a paleo-

ecologic model for conodont speciation during the Permian.

Clark (1974) analyzed factors in Early Permian conodont

paleoecology in Nevada. Perlmutter (1971, 1975) studied

conodonts from the Pennsylvanian and Wolfcampian of Kansas.

Wind (1973, 1974b) described Upper Wolfcampian conodonts

from the Chase Group in Kansas and (1974a) reported on sur­

face features and ontogenetic development in upper Paleo­

zoic conodonts. Permian conodont biostratigraphy of south­

eastern Arizona was described by Butler (1972, 1973).

Babcock (1974a, 1974b) and Croft (1972) have studied conodont distribution and paleoecology in the Lamar Lime­

stone and the Pinery Member of the Bell Canyon Formation in

West Texas. Conodonts of the Kaibab and Toroweap Formations

in Arizona and of the Kaibab and lower Plympton Formations

in Utah and Nevada have been discussed by Bruns (1973)#

Baird (1975) and Baird & Collinson (1975). E. Marcantel

(1973) erected the first multielement conodont species from

the Gerster Formation in Utah and Nevada; Bissell (1974)

discussed Gerster conodonts in conjunction with the Permian-

Triassic boundary in the Cordilleran miogeosyncline. Heiman

(1972) employed conodonts in defining the Pennsylvanian-

Permian boundary in the Casper Formation of southeastern

Wyoming and Verville and others (1973) described biozona­

tions of upper Paleozoic units in a well in Uinta County,

Wyoming that included Permian conodonts.

Outside of the United States, the Conodont Research

Group (1972, 1974) has catalogued conodonts recovered from

the Nabeyama and Adoyama Formations at the Permian-Triassic

boundary in Japan. Barskov and Koroleva (1970) reported

the first Upper Permian conodonts recovered in Russia.

Jorden (1969) described conodonts from the Zechstein Lime­

stone. Kozur (1974a, 1974b) included conodont evidence in

his discussion of the age and stratigraphic position of the 6

Zechstein Limestone of Germany and of the Permian-Triassic boundary in germanic and Tethys deposits. The effects of

Pennsylvanian-Permian glaciation on conodont distribution in Australia were described by Nicoll (1975).

In addition to the above mentioned papers dealing with

Permian conodonts of specific geographic areas, several general studies have appeared. Clark (1972) has analyzed the Early Permian crisis and its effect on subsequent cono­ dont taxonomy. Druce (1972) described the distribution of upper Paleozoic and Triassic conodonts and the recognition of possible biofacies. Finally, in the first volume of the new Catalogue of Conodonts, Ziegler (1974) has described and illustrated several Permian species.

Methods of Study - Complete Gerster sections were measured at six localities in eastern Nevada and two local­ ities in western Utah (Fig. 1). At five of these locali­ ties, carbonate units in the upper Plympton Formation were also sampled. In addition one complete section of Upper

Permian carbonates was measured at Montello in northeastern

Nevada. These sections were taken at the same localities as those reported by Wardlaw (1974b). Samples were col­ lected, exposure permitting, at 10 ft intervals. 1 2 0 0 gm of each sample were processed in the laboratory, using the NEVADA UTAH

10 20 30 —I_ _I_ —I MILES

<0 20 5 0 4 0 SO J- _l I I KILOMETERS

1 MEDICINE RANGE 7IJA, 73JD 2 PHALEN BUTTE 71JB, 72JG 3. CURRIE RAVINE 71 JC, 73JC 4 S. PEOUOP MTNS 7IJD 5 BUTTE MTNS. 72JB .73JF 6 CONFUSION RANGE 7IJE, 73JA 7 CHERRY CREEK MTNS 7U F 8 GOLD HILL 7 IJ I 9 MONTELIO 72JH n

Figure 1. Map of study area showing location of measured sections * standard techniques described by Cooper and Whittington

(1965) . Polished slabs and, in some cases, thin sections were examined for petrologic data. The carbonate classif cation of Dunham (1962) is used in describing the samples STRATIGRAPHY

Regional Setting - The study area lies in the Cor- dilleran miogeosyncline, east of the Antler and Sonoma orogenic belts and west of the Sevier orogenic belt (Fig. 2;

Armstrong, 1968a, 1968b; Roberts, 1968). Upper Pennsyl­ vanian and Lower Permian rocks of this area include a highly variable mixture of clastic, carbonate and evaporite sedi­ ments (Armstrong, 1968b; Bissell, 1962a, 1962b, 1964, 1967,

1970; Roberts and others, 1965; Stevens, 1965, 1966;

J. Marcantel, 1975; Yochelson and Fraser, 1973). Upper

Permian rocks consist of two widespread marine limestone units, the Kaibab and Gerster Formations, separated by and intertonguing with dolomite and chert of the Plympton For­ mation (Bissell, 1964; Browning, 1973a, 1973b). East of the study area in western and central Utah the Kaibab, Plympton and Gerster Formations intertongue with carbonate units of the Park City Formation. North and northeast of the Permian shelf in Nevada and Utah was the Phosphoria Basin in which phosphatic carbonate, chert and shale accumulated (McKelvey and others, 1959). Permian rocks southeast of Nevada and

Utah include marine and nonmarine sandstone, siltstone, 9 10

****£■ RIVER *>"* ROCKY ORE IDAHO MOUNTAIN NEV UTAH PROVINCE

Wtrdovtf .Salt LoK« CiTy

o o r t e z - UWT*- ***S

R*no •E ly

COLORADO

PLATEAU

PROVINCE

GREAT UTAH BASIN ARlZ

0 100 200 — i

SCALE IN MILES

MODIFIED FROM ROBERTS (1968)

Figure 2. Structural Setting 11 shale, and carbonate (Bissell, 1969).

In Late Permian (Silberling and Roberts, 1962, p. 36;

Roberts, 1968, p. 108) or Early Triassic time (MacMillan,

1971, p. 153-154; Nichols, 1971, p. 171; Speed, 1971, p. 199-200; Silberling, 1973) the Sonoma orogeny occurred west of the study area (Fig. 2). An unconformity of unknown extent, separating the Gerster Formation from overlying

Lower Triassic rocks, probably reflects the effects of the

Sonoma orogeny in the study area. It is possible that parts of the Phosphoria Basin were unaffected by the orogeny and that deposition there may have been continuous from Permian

into Triassic time (Sheldon and others, 1967, p. 165).

Stratigraphy of the Gerster and Related Formations -

During Late Leonardian and Early Guadalupian time, wide­ spread carbonate deposition in the Nevada-Utah miogeosyn- cline produced the units assigned to the Park City Group

(Kaibab, Plympton, and Gerster Formations)* These deposits grade northward into phosphatic shale, chert and carbonate of the Phosphoria Formation within the Phosphoria Basin

(Fig. 3; Bissell, 1962a, 1962b, 1964, 1967, 1970; Collin­ son, 1968; Sheldon and others, 1967; McKelvey and others,

1959; Roberts and others, 1965) . The margins of the Upper

Permian sheIf-basin complex were marked on the northeast 12

SHEDHORN' ^fr-FMT '•

I0 A H 0 O * % • • • • ! • •

* « PHOSPHOR (A o "'’ WYOMING * • • • • FM

\ NEVADA

a c a MUOSTOMC, PMOSFMOAITE, CARM3MATE SANDSTONE CHEAT FACIES FACIES FACIES

O K» 200 L. I_ I MILES

Figurfe 3. Paleogeographic framework of the Phosphoria Basin (after Roberts and o t hers, 1965) 13 by deposition of the Shedhorn Sandstone and on the south­

east by redbed deposits. Sandy carbonate units of the

Edna Mountain Formation lie west of Gerster deposits in central Nevada, suggesting a possible barrier between the

Gerster shelf and the Pacific Ocean of Permian time

(McKelvey and others, 1959; Roberts and others, 1965).

Boutwell (1907, p. 443-446) proposed the name Park

City Formation for an arenaceous, cherty carbonate sequence

in Big Cottonwood Canyon near Salt Lake City, Utah. In Utah, the Park City Formation is unconformably underlain by Penn­

sylvanian quartzite and sandstone (Tensleep Sandstone and

Weber Quartzite) and overlain, apparently unconformably, by

Triassic red shale (Woodside Formation) or shale and thin

carbonate units (Dinwoody Formation; McKelvey and others,

1959). Its age is considered to be Late Leonardian to

Capitanian (Dunbar and others, 1960; Yochelson, 1968).

Park City Group - Based on their work on the Permian rocks of the Confusion Range in western Utah, Hose and

Repenning (1959, p. 2178) raised the Park City Formation to group status and included in it the Kaibab, Plympton and

Gerster Formations. Within the study area the Park City

Group is underlain conformably by the Lower Permian Arcturus

Group and overlain unconformably by the Lower Triassic 14 Thaynes Format ion.

Kaibab Formation - The name Kaibab Formation was pro­

posed by Darton (1910, p. 21) for the limestone that caps

the Kaibab Plateau on the north rim of the Grand Canyon. A

reference section of crystalline, cherty, fossiliferous

limestone interbedded with calcareous sandstone was estab­

lished by Noble (1928, p. 41-46) at Kaibab Gulch in southern

Utah. In his description of the stratigraphic sequence in

the Confusion Range, Newell (1948, p. 1057) first identified

the Kaibab Formation in eastern Nevada and west central

Utah. Within the study area, the Kaibab Formation ranges in

thickness from 210 to 487 ft (65 to 150 m) (Baird, 1975).

It consists of massive, cliff-forming limestone and dolomite,

commonly containing chert nodules in the upper part. Bryo-

zoans, productacean brachiopods and crinoids are present in

the limestone and some crinoid stems occur in the dolomite

(Bissell, 1964). Baird (1975), Baird & Collinson (1975) and

Behnken (1975a) have described conodonts of the Kaibab For­

mation. The Kaibab Formation conformably overlies the Arc-

turus Group (Leonardian) and is gradational with the over-

lying Plympton Formation (Bissell, 1964). The age of the

Kaibab Formation is considered to be Late Leonardian (Dunbar

and others, 1960, p. 1782; Yochelson, 1968, p. 624; Baird,

1975; Baird & Collinson, 1975). 15 Plympton Formation - Hose and Repenning (1959, p. 2181) proposed the name Plympton Formation for a sequence of chert and dolomite exposed on Plympton Ridge in the Confusion

Range, west central Utah, Within the study area the Plympton

Formation varies in thickness from 150 to 850 ft (46-260 m) and is composed primarily of silty dolomite and chert with lesser amounts of quartz siltstone, sparse chert-granule conglomerate, pelletal phosphorite and vuggy limestone

(Bissell, 1964* Browning, 1973a, 1973b). Brachiopods, bry- ozoans, crinoids, and gastropods occur in limestone and some dolomitic units within the Plympton Formation, as do micro­ scopic remains of bryozoans and algal plates in micritic dolomite (Browning, 1973a, 1973b; Yochelson and Fraser,

1973). Conodonts have been reported from some units of the

Plympton Formation (Clark and Behnken, 1971; Behnken, 1972,

1975a; Baird, 1975, and Baird & Collinson, 1975). The

Plympton Formation is gradational with both the underlying

Kaibab Formation and the overlying Gerster Formation, Var­ ious authors place its age in a range from Late Leonardian to Late Wordian (Dunbar and others, 1960, p. 1782; Bissell,

1964, p, 627; Sheldon and others, 1967, p, 160; Yochelson,

1968, p. 623; Yochelson and Fraser, 1973, p. 28; Baird, 1975;

Baird & Collinson, 1975; Behnken, 1975a), 16 Gerster Formation - The Gerster Formation was named by Nolan (1930, p. 431-432; 1935, p. 39) from outcrops of thin-bedded, sandy, shaly, and cherty limestone exposed in

Gerster Gulch in the northwest corner of the Gold Hill

Quadrangle, Utah. Within the study area, the Gerster For­ mation consists of interbedded cherty packstone and wacke- stone and nonresistant silty limestone and calcareous silt- stone. It is widely distributed in east central Nevada and west central Utah (Fig. 1). To the south and west of the study area, Gerster deposits have been structurally or ero- sionally truncated; to the north and east the Gerster For­ mation grades into other formations. Gerster deposits thin northward along a line passing through the southern Pequop

Mountains and the Gold Hill region (Fig. 4). Along this line Gerster thicknesses are slightly in excess of 200 ft

(60 m) . The Gerster Formation thickens southward to a max­ imum of 1,100 ft (330 m) in the Confusion Range. The Gerster

Formation is gradational with the underlying Plympton Forma­ tion and is unconformably overlain by the Lower Triassic

Thaynes Formation. Gerster deposits in the southern Pequop

Mountains and Gold Hill region apparently reflect the effects of continued uplift along a structural high that acted as a partial barrier between the Gerster shelf and Phosphoria NEVADA UTAH

HUES

KILOMETERS

I MEDICINE RANGE 2. PHALEN BUTTE 3 CURRIE RAVINE 4 S. PEQUOP MTNS 5. BUTTE MTNS 6. CONFUSION RANGE 7 CHERRY CREEK MTNS 6 GOLD HILL 9 MONTEILO

Figure 4. Isopach map in feet, of present-day thickness of the Gerster Formation le Basin (Wardlaw, 1974b). North of the high at Montello,

Nevada, Upper Permian carbonates lithologically transi­

tional between the Gerster and phosphoria Formations reach

a thickness of 1000 ft. To the east, Gerster deposits

grade into parts of the Park City Formation (McKelvey and

others, 1959? Roberts and others, 1965).

The Gerster Formation is abundantly fossiliferous,

containing spiriferid and productacean brachiopods, ramose and fenestrate bryozoans, crinoid ossicles and bivalves.

Fish teeth and plates, conodonts, and phosphatic internal molds of bivalves, gastropods, ostracodes and foraminiferids were recovered in heavy residues.

The Gerster Formation is divided into three parts, based on outcrop pattern, lithology and faunal content.

South of the structural high separating the Gerster shelf and Phosphor ia £Sasin, the third part is present only in the

Confusion Range section. In addition, limestone beds in the upper Plympton Formation were considered at most Gerster sections because they are similar and probably deposi- tionally related to the Gerster Formation. Details of lithology, silt content, megafossil content, conodont abundance and distribution for each measured section are recorded (Appendix A, Figs. 26-34). 19 Upper Plympton Formation - Limestone beds in the upper Plympton Formation are medium-bedded, yellowish-gray,

silty, brachiopod wackestone to packstone. They occur within a predominantly dolomitic, cherty sequence. Mega­ fossils include bryozoans and spiriferid and productacean brachiopods that appear similar to those encountered in the

Gerster Formation. Three conodont species are represented,

Anchiqnathodus n. sp., Ellisonia n. sp. and Neospathodus arcucristatus Clark and Behnken. Abundance of individual conodont elements is generally low, less than 2 specimens per 100 gm of dissolved sample.

Lower Gerster Formation - The basal 50-100 ft

(15-30 m) of the Gerster Formation consist of thick-bedded to massive, light-gray, brachiopod/crinoid packstone with up to 25% spar cement. Silt is sparse in these packstone units.

Covered, silty intervals separating the outcropping ledges are also uncommon. Chert occurs as nodules and stringers, but is far less abundant than in the middle and upper

Gerster Formation. Megafossils include abundant crinoids

and spiriferid and productacean brachiopods (Figs. 5 & 6 ) .

Bryozoans are present, but they increase in abundance

farther up the section. Brachiopods are preserved as large whole shells and large fragments that are frequently Figure 5. Photomicrograph of sparry brachiopod packstone (71 JE—55); Note fossil fragments in matrix; Bar = 0.1 mm.

Figure 6 . Photomicrograph of sparry crinoid packstone (71 JD-20)r Note A-crinoid, B^brachiopod spines; Bar * 0.1 nan. 21 silicified (Figs. 13 & 14). In addition crushed brachiopod,

crinoid and bryozoan fragments ranging from .10 to .25 mm

constitute a shell sand fraction in many rocks (Fig. 8 ).

Two conodont species, Ellisonia n. sp. and Neospathodus

arcucristatus Clark & Behnken were recovered from the lower

Gerster Formation. Abundance of individual conodont elements

is generally higher than in any other part of the section

(from 6 to 20 specimens per 100 gm of dissolved sample).

Middle Gerster Formation - Overlying the basal massive

units is a sequence of ledge-forming, thin- to medium-bedded,

light-gray, brachiopod/bryozoan/crinoid packstone and wacke-

stone units (Figs. 7, 10, 11 & 12). These are interbedded with nonresistant silty limestone and calcareous siltstone

that is typically coverea and forms slopes. The thickness

and frequency of covered slope intervals increases upward.

Pock sequences assigned to the middle Gerster Formation

vary in thickness from about '^0 ft (48 m) in the southern

Pequop Mountains to roughly 80U ft (240 m) in the Confusion

Range. Silt is present in limestone units throughout the middle Gerster Formation in the Confusion Range (Figs. 7 &

11) and much of the Medicine and Cherry Creek Ranges, but is

less abundant in other sections (Appendix A, Figs. 26-34).

Chert stringers and nodules are more common than in the 22

Figure 7. Photomicrograph of aicritic brachiopod packstone (71 JB-350) t Note irregular white grains of silt and very fine sand size quartz; Bar * 0.1 mm.

Figure 8. Photomicrograph of fossil fragments in micritic packstone (71 JE-55) ; Note A ^“brachiopod shell and spine, B~fosail fragments identifiable as crinoidali Bar • 0.1 m . 23

Figure 9. Photomicrograph of fossil fragment packstone (71 JE-945)7 Note A*large crinoid fragment, sparry frag ments in matrix~fossil hash of crinoids; Bar * 0.1 mm.

Figure 10. Photomicrograph of layered brachiopod packstone (71 JC—444); Note T=top, A=brachiopod, B**ramose bryozoan, Ocrinoidj Bar - 0.1 mm. FIgure 11. Photomicrograph of crinoid vackeatone (71 JE-707) undar crossed nichols; Note Interference figures in quartz silt; Bar » 0.1 nan.

Figure 12. Photomicrograph of brachiopod gralnstone (72 JH-1025); Note A “brachiopod shells, B-crinoid ossicle; Bar ■ 0.1 mm. 25

Figure 13. Photomicrograph of chert replacement in sparry packstone (71 JE-520) under crossed nichols; Note T»top, A-patches of chert around quartz grains in matrix, B»si- licified portion of brachiopod shell, C^chert replacing sparry calcite in geopetal structure beneath brachiopod; Bar “ 0.1 ran.

Figure 14. Photomicrograph of selective silicification of fossil grains in packstone (71 JE-55) under crossed nichols; Note A*silicified brachiopod, B*patch of chal­ cedony in calcareous brachiopod shell, C“calcareous crinoid ossicle; Bar * 0.1 nm. basal Gerster Formation. The amount of chert increases

toward the top of beds and overall abundance increases up­ ward in each section. Megafossils commonly found in the middle Gerster Formation include brachiopods# crinoids and bryozoans. Brachiopods occur throughout the sequence# but crinoid abundance decreases toward the top. Bryozoan abun­ dance is variable# but higher than in the basal Gerster For­ mation. Fossil preservation is similar to that in the basal

Gerster Formation except that the shell sand fraction is re­ duced or absent. Conodont abundance in terms of discrete elements is generally lower than in the basal Gerster Forma­ tion (usually less than 6 elements per 100 gm of dissolved sample)# but species diversity increases. Ellisonia n. sp.,

Neoqondolella n. sp., Neospathodus arcucristatus Clark &

Behnken, Neospathodus divergens Bender & Stoppel# and

Xaniognathus tribulosus (Clark & Ethington) are represented within the middle Gerster Formation.

Upper Gerster Formation - The uppermost 2 50 ft (75 m) of Gerster section at the Confusion Range consist of thin- to medium-bedded# brownish-gray# silty, chert-bearing# calca- renite packstone (Fig. 9). Dark chert composes up to 80 per cent of the rock. Limestone outcrops are separated by numer­ ous# thick covered intervals apparently composed of platy calcareous siltstone and silty limestone. Megafossils constitute 2 to 3 per cent of the rock and consist of cri- noids, gastropods, bryozoans and brachiopods. Biogenic

fragments, probably including algae, form a fine (less than

.15 mm) calcarenite sand that provides the grain support in the packstone. No conodonts were recovered from this interval. CONODONT DISTRIBUTION AND BIOSTRATIGRAPHIC FRAMEWORK OF THE GERSTER FORMATION

Samples from the Gerster Formation and the uppermost limestone beds in the Plympton Formation at eight localities

(Fig. 1) have yielded conodont elements assigned by the author to five genera and six species. (Conodont distribu­ tion at Montello is discussed separately.) These include

Ellisonia n. sp., Neospathodus arcucristatus Clark & Behnken,

Neospathodus divergens (Bender & Stoppel), Anchignathodus n. sp., Xaniognathus tribulosus (Clark and Ethington) and

Neoqondolella n. sp. The distribution of conodonts recov­ ered from measured sections is recorded in detail in Appen­ dix A (Figs. 26-34) and Appendix B (Tables 1-9) and is also summarized on the correlation charts of Gerster measured

sections (Figs. 16, 17, & 18).

Ellisonia - Elements of Ellisonia are more abundant than those of any other conodont genus in the rocks studied.

Their distribution is ubiquitous throughout the Gerster

Formation and limestone beds in the uppermost Plympton

Formation with the exception of the upper 250 ft (75 m) at

28 29 the Confusion Range. A few barren samples within an other­ wise fossiliferous interval are recorded in the Appendix figures, but are considered insignificant because the overall low conodont abundance dictates a high probability of not finding conodont elements in some units where they are present.

Neospathodus - Two species of Neospathodus are represented, N. arcucristatus Clark and Behnken in the upper Plympton Formation and in much of the Gerster For­ mation, and N. divergens (Bender and Stoppel) in the upper part of the Gerster Formation. Ranges of the two species do not appear to overlap, but poor preservation and low conodont abundance preclude a close determination of range boundaries.

It is possible that Neospathodus arcucristatus and

N. divergens belong in the apparatus of the genus Ellisonia and constitute the distinguishing elements for two separate species. Present evidence is inconclusive (see Neospathodus section of systematics). The author has chosen to treat

N. arcucristatus and N. divergens as separate species following Clark and Behnken (1971), and Behnken (1972,

1975a). 30 Anchignathodus n. sp. - Elements of this species are known only from the limestone beds in the uppermost

Plympton Formation in this study. They are not recorded frotn the Gerster formation. Baird (1975) and Baird &

Collinson (1975) report examples of Anchignathodus n. sp. from the Kaibab Formation.

Xaniognathus tribulosus (Clark & Ethington) - Elements of Xaniognathus tribulosus have been recovered from all sections except the southern Pequop Mountains. Examples of

Xaniognathus tribulosus generally occur in samples con­ taining specimens of Neoqondolella n. sp.; however, the

Xaniognathus elements .* few in number, small, delicate and poorly preserved. It seems possible that their absence in the southern Pequop Mountains, (from which specimens of

Neoqondolella n. sp. were recovered) may be due simply to the vagaries of sampling.

The close association of Xaniognathus with Neodon- dolella suggests some sort of genetic relationship (Sweet,

1973a). Either species assigned to Neoqondolella were platform elements in the Xaniognathus apparatus or, as suggested by Sweet (per. com.) based on studies of Triassic conodonts, Xaniognathus episodically gave rise to apparently single member species of Neoqondolella. 31

Neoqondolella n. sp. - Examples of Neoqondole1la

n. sp. were not recovered in the basal portion of the

Gerster Formation. The lowest occurence of these elements

is from 150 ft (45 m) to 250 ft (75 m) above the base. At

Phalen Butte, Currie Ravine, Cherry Creek and Gold Hill

Neoqondolella n. sp. ranges essentially continuously from

the level of its first occurence to that of its last, but

at Medicine Range, Montello and Confusion Range it occurs

in several intervals separated by 150 ft or more of rocks with elements of Ellisonia, but not Neoqondolella.

Four conodont zones are established (Fig. 15). The

lowest, Zone A, is identified by the joint occurrence of

Anchignathodus n. sp., Ellisonia n. sp. and Neospathodus

arcucristatus Clark & Behnken. It is confined to the upper

Plympton Formation, but poor exposures and silicified rocks

present in this interval precluded detailed study and

precise boundary determinations. The overlying Zone B

contains examples of Ellisonia n. sp., Neospathodus arcu­

cr istatus, and, in some sections, Xaniognathus tribulosus

(Clark & Ethington) and Neoqondolella n. sp. Zone B lacks

elements of Anchignathodus n. sp. The uppermost occurrence

of elements of Anchignathodu3 n. sp. marks the boundary between Zones A & B, At present this boundary is 32 CONODONT ZONES

B

Ellisonia, n. sp.

Anchignathodus, n. sp.

Neospathodus arcucnstatus Clark and Behnken

Xaniognathus tributosus Clark and Ethington

Neogondolella, n. sp.

Neospathodus divergens Bender and Stoppei

Figure 15. Ranges of conodont species by zones. The contact between the Plympton and Gerster Formations is at the base of Zone B. 33

arbitrarily placed at the base of the Gerster Formation

because the exact range of Anchignathodus n. sp. in the

upper Plympton Formation is uncertain. The top of Zone B

is marked by the last occurrence of Neospathodus arcucris­

tatus . Zone C includes Ellisonia n. sp. and spotty occur­

rences of Xanioqnathus tribulosus and Neogondolella n. sp.

Its base is the uppermost occurence of Neospathodus arcu­

cr istatus and its top the lowest occurrence of Neospathodus

divergens. The uppermost Zone, Zone D, is identified by

the presence of Neospathodus divergens (Bender & Stoppel),

It also contains Ellisonia n. sp. and, in some sections,

Neogondolella n. sp. and Xaniognathus tribulosus. The first

occurrence of Neospathodus divergens marks the base of

Zone D; the upper limit is defined by the erosional uncon­

formity separating the Gerster Formation from the Triassic

Thaynes Formation.

Zone C is characterized by a lack of specimens of

Neospathodus arcucristatus or Neospathodus divergens. In

all other respects, its conodont fauna is similar to Zones

B and D. Specimen abundance is low and preservation poor

in the upper Gerster Formation. Thus, the actual strati- graphic ranges of N. arcucristatus and N. divergens are

uncertain. Further work may result in abolition of Zone C. 34 Behnken (1975a) has updated the conodont zonation of the Plympton and Gerster Formations proposed by Clark and

Behnken (1971). He recognized a Neoqondolella rosenkrantz i-

Neospathodus arcucristatus Assemblage Zone in the lower

Gerster Formation and the upper 100 ft of the Plympton For­ mation and a Neoqondolella rosenkrantzi - Neospathodus divergens Assemblage Zone in the upper Gerster Formation.

Associated with the N. rosenkrantzi (=Neogondolella n. sp. of this report)- N, divergens Assemblage Zone, Behnken

(1975a, p. 293) also reported elements of Ellisonia tribu-

losa (=Xaniognathus tribulosus of this report). Behnken did not discuss additional conodont elements recovered from either zone, presumably because they are long ranging and undiagnostic. Examination of conodont elements reported by

Clark and Behnken (1971) indicates, however, that ramiform elements herein assigned to Ellisonia n. sp. were also recovered from the Plympton and Gerster Formations.

There is close agreement between the zones of Behnken

(1975a) and this paper for the Gerster Formation. Behnkenrs

Neogondolella rosenkrantzi-Neospathodus arcucristatus

Assemblage Zone contains the same elements as Zone B of this paper and his N. rosenkrantzi-N. divergens Assemblage

Zone the same elements as Zone D. Unlike samples processed 35 for this study, Behnken's sampling (1975a, p. 287) indicates very little stratigraphic gap between the last occurrence of Neospathodus arcucristatus and the first occurrence of

Neospathodus divergens. Thus, Behnken has no interval equivalent to Zone C of this paper.

In the upper Plympton Formation, Behnken (1975a) has recovered Neospathodus arcucristatus and possibly Neoqon­ dolella n. sp. The author has seen no specimens of Neo­ qondolella n. sp. in Plympton units, but has recorded

Neospathodus arcucristatus, Ellisonia n. sp. and Anchig- nathodus n. sp. Anchignathodus n. sp. is not abundant in

Plympton rocks and was probably not recovered by Clark &

Behnken (1971) or Behnken (1975a). Behnken1s report of

Neogondolella n. sp. in the Plympton Formation is puzzling since samples from units in five Plympton sections examined for this paper yielded no N. n. sp. Possible explanations include (1) specimens of N. n. sp. were not actually recovered from Plympton units, but their presence was inferred due to the occurrence of the associated Neospathodus arcucristatus (see Behnken, 1975a, Text-Fig. 2, p. 287) or

(2) Gerster units containing N. n. sp. were placed in the upper Plympton Formation by Behnken. Additional study of

Plympton conodonts should resolve discrepancies between 36 the zonations of Behnken (1975a) and this report.

Conodont zones A through D are employed in correlating measured Gerster sections (Figs. 16, 17 & 18). The datum line for these cross-sections is the last occurrence of

Neospathodus arcucristatus Clark & Behnken. 37

OVER 5 0 % Xoniognothus COVERED tribu/osus

CHERTY Neogondoteffa gg N n, ip. LIMESTONE

L / o / CHERTY PRA Anchignathodus DOLOMITE n. Bp. Y r ^

UNIDENTIFIED THIN CHERTY LIMESTONE R RAM I FORM WITH UP TO 50% COVERED ELEMENTS 1 1 H Neospathodus PHOSPHATE a arcucr/sfoius

Necspathodus E H i s o n / a d E n. Bp d i v e r g e n s

LEGEND FOR FIGURES 16-18 w

MEDICINE RANGE PHALEN SECTION E C U R R IE SOUTHERN BUTTE GOLD ZONE D SECTION R W K W HILL „ SECTION section SECTION ZO N E C o XN IK-JHi raf=ii Plympton Em ZO NE S '■HI

ZO N E A

HONUONTAL SCALE IN MILES

Figure 16. East-west cross section of Gerster Formation in Nevada and Utah. w Datum is top of Zone B. 00 GERSTER PHOSPHOR IA BUTTE BASIN b a s in montello SECTION MTU CHERRY SECTION Z O N E D CREEK SECTION ar— r

wpp i no. Z O N E C SECTIONm I l JEJ Z O N E B

ptymptonFm.

I • I Z O N E A

HORIZONTAL SCALE IN MILES

Figure 17. Southwest-northeast cross section of Gerster and related formations in Nevada. Datum is top of Zone B. I N CONFUSION GERSTER PHOSPHORIA RANGE BASIN BASIN MONTE110 SECTION SECTION O d d

ZO NE 0 GOLD HILL ZONE C SECTION

ZO NE B

ZONE A ■ LJI ■ C-lHi

■■I ] IMM Homzopmu. scale IN MILES

Figure 18. North-south cross section of Gerster and related formations in Nevada ______and Utah. Datum is top of Zone B. o DEPOSXTIONAL ENVIRONMENT AND CONODONT PALEOECOLOGY

Gerster sedimentation occurred in an open marine shelf sea south of the Phosphoria Basin. Configuration of the shelf is not clearly demonstrable because of post­ deposit ional erosion. South of the Confusion Range and southwest and west of the Medicine Range and Butte Mountains, correlative rocks are missing. The nearest Permian rocks of similar age in these directions are marine limestone deposits in West Texas (Cooper & Grant, 1969, 1972, 1974), at El Antimonio in northwestern Mexico (Cooper, 1953), in the Inyo Mountains of southeastern California (Merriam

& Hall, 1957,* Gorden & Merriam, 1961) and in the Diablo

Formation in the Candalaria Hills of southwestern Nevada

(Page, 1959). These deposits are correlated with the

Gerster Formation on the basis of similar brachiopod faunas

(Yochelson, 1968; Wardlaw, per. com.), but lie hundreds of miles away from the study area. It is quite possible that the Gerster shelf was at least partially separated by land masses or island chains from depositional areas in

West Texas. The Gerster Formation at the Confusion Range,

41 42

Butte Mountains, Medicine Range and Cherry Creek Range contains a much higher percentage of silt than at other localities. This silt distribution in southern and western sections suggests terrigenous source areas, now removed by erosion, to the south and southwest. Conodont correlations of the upper Plympton and Gerster Formations (Figs. 17 &

18) show thick Plympton deposits in the southern part of the study area thinning northward toward the Phosphoria

Basin where equivalent age units are represented by marine carbonates. Browning (1973a, 1973b) attributed the depo­ sition of the Plympton Formation to nearshore, intertidal and supratidal conditions. The distribution of these deposits suggests a land area to the south during Plympton time that may have persisted into Gerster time. The pro­ vinciality of Gerster conodont taxa compared with those of equivalent rocks in West Texas may also indicate the pos­ sibility of a complete or partial barrier between the West

Texas and Gerster seas.

The extent of the northern and eastern margins of the Gerster shelf is less speculative. Northwest of the study area in north central Nevada, Roberts (1951) iden­ tified a sequence of shale, limestone, sandstone and chert conglomerate that he named the Edna Mountain Formation. This formation contains brachiopods similar to those found

in the Gerster Formation (Williams, 195 9). The high sand content and general aspect of the Edna Mountain Formation

suggest very nearshore deposition (Roberts and others,

1965; Coats & Gorden, 1972) and would indicate land or an

island chain separating the Gerster shelf from marine areas that lay to the northwest. North of the study area and partially isolated from it by a structural high (see

Montello Section), dark chert, phosphatic and carbonaceous mudstone, phosphorite, cherty mudstone and dark carbonate rock of the Phosphoria Formation were deposited, in part, at the same time as the Gerster Formation (McKelvey and others, 1959; Sheldon and others, 1967; Yochelson, 1968).

Because of the basinal configuration of isopached Phosphoria thicknesses and the presumed need for upwelling of organic rich waters from ocean depths to produce phosphatic deposits,

McKelvey and others (1959) have interpreted the depositional environment of the Phosphoria Formation as deeper water than that of the Gerster and Park City deposits. Conodont cor­ relations between the Plympton and Gerster Formations of the study area and the uppermost Permian carbonates on the southern margin of the Phosphoria Basin at Montello suggest thick limestone sequences at Montello are equivalent to dolomite* chert* and southward thinning carbonate units in the Plympton Formation (Figs. 17 & 18). This facies relationship may be interpreted as indicative of marine transgressions from north to south in the study area.

These transgressions probably represented an expansion southward of the deeper waters of the Phosphoria sea onto the Gerster shelf. East of the study area, carbonate rocks lithologically and paleontologically similar to the Gerster

Formation were deposited in Utah and Wyoming (Park city

Formation; McKelvey and others, 1959; Sheldon and others,

1967; Yochelson, 1968). Shoaling of the Park City sea is indicated on the east by the presence of coastal sand deposits (Shedhorn Sandstone* McKelvey and others, 1959) and on the southeast by shallow water faunas and sedimentary structures in the Park City Formation (Yochelson, 1968).

The paleotopography of the study area during deposition of the Gerster Formation is suggested in Figs. 4 & 19.

Figure 4, an isopach map of present-day Gerster thicknesses, would by itself be suspect because of the effects of post­ deposit ional erosion. However, Figure 19, an isopach map of the thickness of conodont Zone B, displays similar thickness variations; as do isopach maps based upon brach- iopod zonation of the Gerster Formation by Wardlaw (1974b). 45 IDAHO NEVADAUTAH

o IO 2 0 9 0 _l_ _L_ _J MILES

o 10 20 30 40 50 l_ -J I I L_ -J KILOMETERS

t. MEDICINE RANGE 2. PHALEN BUTTE 3. CURRIE RAVINE 4. S. PEQUOP MTNS.

Sl BUTTE MTNS. 6. CONFUSION RANGE 1. CHERRY CREEK MTNS B. GOLD HILL 9. MONTELLO

Figure 19. Isopach nap in feet, of Gerster Formation from Gerster-Plympton contact to last occurrence of Neospathodus arcucristatus (Zone B) 46

Gerster deposition was thinnest across a northwest-southeast trending high that passes through the southern Pequop

Mountains and Gold Hill areas. Deposits thicken north and south away from this high. It is possible that the southern Pequop Mountains-Gold Hill high was associated with the Cortez-Uinta Axis, a regional positive feature that was episodically active as early as the Cambrian

(Roberts and others, 1965; Armstrong, 1968b; J. Marcantel,

1973, 1974, 1975; Yochelson and Fraser, 1973}. All Gerster brachiopod zones occur in deposits along the high, sug­ gesting a continuous but slower rate of deposition (Ward- law, 1974b), however, conodont Zone D (characterized by

Neospathodus divergens) has not been identified along the high. The absence of Zone D is perhaps indicative of erosion or nondeposition of uppermost Gerster Formation units, but may also be the result of misidentification of

N. divergens among the sparse and poorly preserved conodont elements recovered from the upper Gerster beds.

The depositional environment of the Gerster Formation is difficult to categorize because of its lack of diagnostic environmental fossils and lack of diagnostic sedimentary features. Some conclusions can however, be presented.

Heckel (1972) has discussed recognition of ancient shallow 47 marine environments, presented a hypothetical carbonate depositional model (based on Irwin, 1965) and compared this model to several Recent areas of deposition, including the Persian Gulf (Fig. 20). Plympton-Gerster depositional environments were probably most like those existing today in the Persian Gulf (Browning, 1973a, 1973b), therefore similarities between Plympton and Gerster deposits and those of the Persian Gulf will be noted (Figs. 20 & 25).

Upper Plympton dolomites and cherts were probably deposited in a sabkha-like environment with fringing tidal flats and shallow marine lagoons (Browning, 1973a, 1973b).

Deposits include burrowed dolomicrite which often contains pellets and broken crinoid, brachiopod and gastropod frag­ ments, laminated dolomite, dolomite with chicken-wire textures and length-slow chalcedony rosettes (indicative of the existence and replacement of evaporite layers) and quartz silt layers that may represent aeolian deposits

(Browning, 1973a, 1973b). These Plympton deposits would correspond to the pelleted calcilutite and dolomitic calcilutite with gypsum found in the high subtidal to supratidal environments of the Persian Gulf today (Fig. 20).

The upper Plympton limestone units, as previously described, represent one or more marine incursions into Recent Morins S ed i me nta t i o n Model

DEEPER WATER SHALLOW WATER V , SHALLOW WATER LAND

SEDIMENT BELOW WAVE BASE SEDtMENT ABOVE WAVE BASE WAVES, CURRENTS DAMPED NONMARINE

SANDS MUDS TO SANDY MUDS MUDS , SOME SANDY (tome abraded, lorted) *

biota d i v e n e biota diverse biota restricted \ * SUPRA*! Theoretical (Irwin, 1965) \ t id a l , 1 r sf r T l "7^1 7 \ ' A s k FLFTAL^ OOIIT fY PELLETED LAMINATED •ff. wove bme ) , c REEFS 0LITE x CALCILUTITE CALCILUTITE SHELLY CALCILUTITE^/ tALWUtNMt (locn,|y) ' (« m e th elli) i / 'EVAPORITES (when climate arid)

Persian G u IF / \V / /

O O L IT E " J \ \ ^DOLOMITIC SKELETAL CALCARENITE REEF \ ' CALCILUTITE ^SHALY, SHELLY PELLETED CALCILUTITE' \ with GYPSUM etc CALCILUTITE •GLAUCON,TE STROMATOLITE

Figure 20. Hypothetical carbonate depositional model (after Irwin, 1965) and carbonate deposition on the south side of the Persian Gulf (Heclcel, 1972). £ 49 the very shallow subtidal to supratidal environment of the

Plympton dolomite and chert (Fig. 21). These limestones are thin- to medium-bedded, suggesting that conditions

conducive to their deposition existed only briefly. They

are gradational with very shallow water deposits, suggesting

that they formed in only slightly deeper water and they may

represent the shallowest limestone deposits considered in this study. Brachiopod and bryozoan faunas indicate normal or near normal salinities at the time of deposition of

these limestone units (Wardlaw, per. com.). Shells are not much broken or abraded and lime mud content is high, sug­ gesting that wave and current energy was not great. Silt

is abundant (up to 20% of the rocks). These limestone

units probably formed in an environment similar to the near­

shore part of the skeletal calcarenite model in the Persian

Gulf (Heckel, 1972).

Conodonts recovered form the upper Plympton limestone

units include Anchignathodus n. sp. and Ellisonia n. sp.

and Neospathodus arcucr istatus Clark & Behnken. Other workers report varied environmental preferences for

Anchignathodus. Behnken (1972) and Croft (1972) have sug­

gested that, based on the depth stratified model of cono­

dont distribution described by Seddon and Sweet (1971), 50

calcareous siltatone

abraded calcarenite and calcilutite - Heeke1 micritic wackestone/packstone - Dunham

shelly calcilutite and silty carbonate-Heckel micritic packstone/waekestone - Dunham

sparry whole shell calcarenite - Heckel sparry packstone - Dunham

micritic wackestone/packstone

dolomite and chert

LEGEND FOR FIGURES 21-25 51

JL

Figure 21. Block diagram illustrating depositional environment during upper Plympton time.

J. 1 ^ ^ i A

X

Figure 22. Block diagram illustrating depositional environment during lower Gerster time. 52

DMpming 6«rtf«r Sm

•x *X * "X X* *. X- 'X

Figure 23. Bloclc diagram illustrating depositional environment during middle Gerster time.

Figure 24. Bloclc diagram illustrating depositional environment during upper Gerster time. s N CONFUSION RANGE MONTELLO SECTION SECTION

SECTION

HOMZONW. KALE IN MILES

Figure 25. Hypothetical model of upper Plympton and Gerster deposition and subsequent erosion to present state of preservation. Carbonate terminology compared to that used by Heeke1 (see Legend and Figure 20, this paper). 54 Anchignathodus represents the shallowest known Permian conodont genus in West Texas. Merrill (1972, 1973) states that Anch ignathodus minutus (Ellison) (=Spathognathodus minutus (E)lison) of Merrill) is ubiquitous in Pennsylvanian faunas and displays no strong environmental preferences.

Von Bitter (1972) indicates that Missourian Anchignathodus minutus (Ellison) occurs with his offshore limestone-Strep- tognathodus biofacies. Wind (1973, 1974b) and Butler (1972,

1973) report ubiquitous distribution of species of Anchig­ nathodus in their Permian deposits in Kansas and Arizona.

Clark (1974) in a paper on Early Permian conodont paleo- ecology includes Anchignathodus in a group of deep water forms that survived the Early Permian conodont extinction which he interprets to have destroyed all very shallow water conodont species. Clark does suggest that Anch ignathodus may range into shallow water in some cases.

Data on the distribution of the genus Ellisonia (in the sense of Ellisonia triassica Muller of Sweet, 1970a,

1970b) is difficult to obtain because many conodont articles do not discuss or describe its long ranging ramiform ele­ ments. Wind (1973, 1974b) has described a Wolfcampian species of Ellisonia that ranges throughout all of his rock units except those deposited in areas of extremely 55

abnormal salinity. Butler's (1972, 1973) collections

contain Ellisonia n. sp. at least throughout the Concha

and Rainvalley Formations of southeastern Arizona.

Neospathodus arcucristatus is reported outside the

study area only from the Concha and Rainvalley Formations

of Arizona (Butler, 1972, 1973). These formations were

deposited under shallow, but normal marine conditions.

Species of Anch ignathodus appear to occur within a wide range of depositional environments, at least as in­

dicated by the rock types from which they are recovered.

Within the study area Anchignathodus n. sp. ranges through

the Kaibab Formation (more open marine than the Plympton)

into the very shallow water limestone deposits of the upper Plympton Formation. It is definitely more abundant

in the Kaibab Formation than in most upper Plympton lime­

stone units. Perhaps the very shallow marine depositional environment represented by the thin upper Plympton lime­

stone deposits was near the limit of the normal-restricted marine environment with respect to conodonts and this explains the paucity of Anch ignathodus n. sp., Ellisonia n. sp. and Neospathodus arcucristatus elements in these

limestone units. The ubiquitous distribution of Anchig­ nathodus in normal marine environments may be explained 56 by a depth stratified model such as Seddon and Sweet's

(1971) which permits the existence of conodont groups in

various water levels above a wide variety of substrates.

It might also be explained by some other form of vertical

stratification, such as temperature, light, energy level,

or nutrients. It is also possible that species of

Anch ignathodus were simply tolerant of a wider range of

depositional environments that most other conodonts.

Elements of Anch ignathodus have not been recovered

from the Gerster Formation, although they have been found

in older Permian formations in the study area and are known

from other Permian formations of equivalent age in West

Texas (Behnken, 1972, 1975a; Croft, 1972). In fact the

genus is widespread in Upper Permian rocks around the world

and does not become extinct until the Early Triassic (Sweet

in Teichert, Kummel & Sweet, 1973). Possibly the existence

of a land barrier between West Texas and the Gerster shelf

produced exclusion of Anchignathodus n. sp. from the Gerster

sea while it persisted in areas to the south.

The depositional environment of the basal Gerster

Formation is very difficult to classify. Its sedimentary

and biologic characteristics are those of a "whole-shell"

calcarenite (Heckel, 1972), The fossils indicate an in-situ accumulation of abraded to unabraided whole brach-

iopod shells with subordinate amounts of bryozoans and

disarticulated crinoid stems. Spar content may be 30-40%

of the matrix# but some of this spar is probably the result

of geopetal sheltering effects and not of the actual win­

nowing of mud. Because these deposits occur in the basal

50-100 ft of the Gerster Formation, and because they inter­

tongue with the high subtidal to supratidal Plympton dolo­

mite, chert and siltstone, they may reasonably be inter-

* preted as the earliest preserved sediments of the Gerster

transgression and therefore as the shallowest preserved

sediments of the transgressive phase. Evidence for wave

and current energy level in the basal units is conflicting.

The broken shell fragments composing the sand fraction of

these rocks are highly angular and poorly sorted and are

probably the result of browsing by scavengers and sediment

feeders rather than of breakage and abrasion by waves or

currents. The unbroken state of larger fossils supports

the contention that water energy was not high in this

environment. Spar content of these basal units is higher

than that of the overlying Gerster deposits. This could

be explained as the result of the winnowing of lime mud i under higher energy conditions than those extant in the 58

middle Gerster Formation, but may simply be due to a lower

rate of lime mud production in this interval. Brachiopod

species recovered from this interval suggest shallower water conditions of deposition than those prevailing in

the middle Gerster Formation (Wardlaw, per. com.). The basal Gerster deposits probably formed in the offshore

part of Heckel's (1972) skeletal calcarenite interval, in

shallower water than that which existed during deposition

of the middle Gerster Formation (Fig. 22). Water energy

levels in this basal interval may have been higher than those reflected in the overlying middle Gerster units; it

is possible that the numerous crinoids present in this basal sequence acted as baffles to wave energy and helped

to prevent winnowing and mask surface energy conditions.

Conodont species recovered from the basal Gerster

Formation include Ellisonia n. sp. and Neospathodus

arcucristatus Clark & Behnken. Elements of Ellisonia are ubiquitous throughout the upper Plympton and Gerster

Formations, but they are far more numerically abundant in the basal Gerster than elsewhere. This abundance may be

interpreted as an indication of (1) the existence of optimum environmental conditions for Ellisonia during basal Gerster deposition, (2) a slower rate of deposition 59 of the basal Gerster compared to the upper Plympton and middle Gerster, producing less dilution of accumulating conodont elements by sediment and resulting in more cono- donts per kilogram of processed sample (Lindstrom, 1964),

(3) a combination of 1 and 2. Evidence supporting a slower depositional rate for the basal Gerster is provided by

(1) low silt content of the basal Gerster compared to the upper Plympton and middle Gerster. Significant percentages of silt would suggest terrigenous influx that should increase the rate of sedimentation. (2) the abundance of spar in the basal Gerster Formation. The presence of spar may indicate a rate of lime mud production insufficient to fill all available pore spaces. Evidence supporting an optimum ecologic environment for Ellisonia in the basal

Gerster Formation is less compelling. Butler (1972, 1973) and Wind (1973, 1974b) have stressed the ubiquitous distri­ bution of Ellisonia through all types of normal marine depositional environments in their studies. Apparently

Ellisonia, like Anchignathodus, either tolerated a wide range of environments or existed in similar water conditions above a variety of benthonic environments. Conodonts be­ longing to the genus Ellisonia disappear only in rocks whose lithic and faunal characteristics indicate restricted 60 depositional conditions such as abnormal salinity (Wind,

1973, 1974b) or highly variable salinity, temperature etc. associated with very shallow water (uppermost Gerster deposits at the Confusion Range).

Elements of Neospathodus arcucristatus range through­ out the basal Gerster Formation and, in thick sections, up into the middle Gerster Formation. They are not present in all .samples from this interval, but were recovered where conodont element abundance is high. Their spotty distri­ bution within Zones A & B is probably a function of cono­ dont element abundance and state of preservation. Species of Neospathodus appear to be associated with species of

Ellisonia, and both display similar environmental prefer­ ence; Neospathodus is, however, a more rapidly evolving genus than Ellisonia.

The middle Gerster Formation appears to have been deposited in deeper water and under lower energy conditions than the basal Gerster Formation (Fig. 23). Evidence in support of these conclusions includes the abundance of lime mud in middle Gerster rocks, suggestive of a lack of win­ nowing in an otherwise normal marine environment, and the presence of a deeper water brachiopod fauna than that of the basal Gerster (Wardlaw, per. com.). An increase of 61 silt in limestone units, plus the appearance of silty lime­

stone or calcareous siltstone reflected in slope-forming

intervals, indicates the middle Gerster Formation probably

formed in more turbid water than the basal Gerster. In

general, the depositional environment of the middle Gerster

Formation probably lay somewhere in the shoreward part of

the shaly, shelly calcilutite interval in the Persian Gulf

model of Heckel (1972).

Elements of Ellisonia n. sp. range throughout the

middle Gerster Formation. Near the top of the middle

Gerster Formation, Neospathodus arcucristatus Clark &

Behnken disappears, shortly to be followed by Neospathodus

divergens (Bender & Stoppel). No apparent ecologic factor

dictating this presumed evolutionary change is recorded

in the rocks.

Neoqondolella n. sp. and Xaniognathus tribulosus

first appear in the middle Gerster Formation. The deposi­

tional environment related to the occurrence of species of

Neogondole11a has been discussed by Behnken (1972), Croft

(1972), Butler (1972, 1973), and Clark (1974). All have

concluded that Neoqondolella occurs in relatively deep water or offshore deposits. This theory would appear to be supported by the distribution of Neogondole11a n. sp. in the Gerster Formation. It has not been recovered from basal

Gerster units laid down during the shallow, initial trans­ gress ive phase of the Gerster sea. It is not found in the shallow upper Plympton limestone of the study area, although it is present in the thicker, age-equivalent, carbonate sequence at Montello that was deposited on the edge of the

Phosphoria Basin, probably in deeper water. It is recorded only in the very top of Gerster sections deposited along the regional structural high (southern Pequop Mountains and Gold Hill sections) where the water may have been too shallow during most of Gerster deposition to permit Neo- qondolella n, sp. to exist. Xaniognathus tribulosus

(Clark & Ethington) is associated with Neogondolella n. sp. and its distribution appears to be controlled by the same factors. Species of Xaniognathus are also associated with all species of Neogondolella discussed by Behnken (1972),

Croft (1972), and Clark (1974) in their papers. Butler

(1972, 1973) has recovered no species of Neoqondolella and only 3 poor specimens of the O element of Xaniognathus from his entire southeastern Arizona Permian sequence. He attributes this fact to the shallowness of the Permian sea in Arizona. This explanation may be valid as well for the

Kaibab Formation, from which Baird (1975) has recovered 63 only one specimen of Neogondolella idahoensis (Youngquist,

Hawley, & Miller) and a few elements of Xaniognathus abstractus? {Clark & Ethington).

Water depth itself may not be the factor controlling the distribution of species of Neogondolella and Xaniognathus.

Temperature, available light, stability of environmental factors, or some other ecologic parameter attendent on depth variation may actually control their distribution.

The uppermost Gerster deposits, preserved only in the

Confusion Range section, reflect a marked change from the underlying Gerster units (Fig. 24). Thick, silty covered intervals are interbedded with thin beds of cherty limestone and calcareous chert. Where silicification has not destroyed limestone textures, the rocks are observed to contain broken and abraded, sand sized skeletal fragments, sparse crinoid plates and brachiopod fragments, ostracod and gastropod shells, possible algal plates, pellets and lime mud. Some limestone units in the Confusion Range are cross-bedded.

The general aspect of these units suggests deposition in a nearshore, subtidal environment that was probably produced during the final regressive phase of the Gerster sea. Epi­ sodes of high wave energy, as well as the activity of sca­ vengers and burrowers, reduced shells to sand size. These 64 grains were probably washed into the lime mud and pellets

forming in bays and lagoons. The normal marine fauna of

the underlying Gerster units has been replaced by gastropods* ostracods and possibly algae. Thick silty intervals prob­ ably mark progradation of terrigenous material onto the

Gerster shelf. In Heckel's carbonate model {Fig. 20), this depositional environment is best reflected by the pelleted calcilutite interval.

Conodonts were not found in the uppermost Gerster deposits. First to disappear are Neogondolella n. sp. and

Xaniognathus tribulosus, followed by Neospathodus divergens and finally Ellisonia n, sp. Apparently the depositional environment became unfavorable for conodonts. Similar dis­ tributions are noted in West Texas (Behnken, 1972* Croft,

1972; Babcock, 1974a, 1974b) where conodonts are not recov­ ered from the reef and back reef deposits of the Delaware

Basin. Temperature, salinity, water depth, pH, nutrient level and other environmental factors are known to be highly variable in such environments. It is impossible to conclude from the rock record which factor controlled the distribu­ tion of conodonts in very nearshore marine environments, but clearly they are often absent from such areas. THE MONTELLO SECTION

In northeastern Nevada, Upper Permian rocks are tran­

sitional lithologically between the Kaibab, Plympton and

Gerster Formations of the study area and the Phosphoria

Formation of southeastern Idaho, Roberts and others (1965)

illustrated a section from Jim Thomas Canyon in this area.

They have assigned the uppermost Permian units to the Ger­

ster Formation. Underlying dolomite, siltstone and fossil-

iferous wackestone units were indicated to be correlative with the upper Plympton Formation or the Meade Peak and Rex

chert members of the Phosphoria Formation.

To ascertain the continuity of conodont distribution on the northern margin of the Gerster depositional environ­ ment, a section of Upper Permian rocks was measured and

sampled near Montello, in northeastern Nevada (Fig. 1).

The section included 1650 ft (495 m) of limestone, dolomite

and siltstone (Appendix A, Fig. 32).

The basal 250 ft (75 m) of the Montello section

consist of thick-bedded to massive, brownish gray, cherty, phosphatic, sparsely fossiliferous wackestone ledges and

65 66 siope-forming intervals probably underlain by siltstone.

Crinoids, bryozoans and productacean and spiriferid brachi- opods are present in the wackestone units, but generally constitute less than 20% of the rock. Conodont elements recovered include Anchignathodus n. sp., three specimens of Neogondolella n. sp. and unidentified, poorly preserved ramiform elements.

Overlying the basal interval is 100 ft (30 m) of olive-gray, medium-bedded dolomite containing nodules, stringers and masses of gray chert. No fossils were re­ covered from this interval.

300 ft (90 m) of thick-bedded to massive, medium gray, cherty, phosphatic, crinoidal wackestone/packstone overlie the cherty dolomite interval. Brachiopods and bryozoans are present in these units, but crinoids consti­ tute the dominant megafossils. Up to 40% of some beds are composed of crinoid fragments. Approximately one-third of the crinoidal wackestone interval consists of slope-forming siltstone units. The only conodonts recovered from this part of the Montello section were poorly preserved uniden­ tified ramiform elements like those contained in the basal

250 ft (75 m) . From approximately 650 ft (195 m) to 1100 ft (330 m), the Montello section consists of medium-bedded to massive, light to medium gray, cherty, phosphatic, brachiopod wackestone/packstone units. About 25% of this interval is composed of slope-forming siltstone beds. Megafossils are predominately productacean and spiriferid brachiopods, but also include crinoids and bryozoans. Recovered conodonts include Ellisonia n. sp., Neospathodus arcucristatus Clark and Behnken, Xaniognathus tribulosus (Clark & Ethington) and Neogondolella n. sp.

The uppermost 550 ft (165 m) of the Montello section are primarily covered, but contain sparse outcrops of medium to thick-bedded, dark brownish gray, silty, cherty mudstone.

Megafossils are rare, only a few broken fragments of cri­ noids, brachiopods and bryozoans were observed. Conodonts include Ellisonia n. sp. and one element of Neospathodus divergens (Bender & Stoppel).

The upper 1050 ft (315 m) of the Montello section are indisputably correlative with the Gerster Formation. Lith- ologically the interval from about 600 ft (180 m) to 1100 ft

(330 m) is like the basal and middle Gerster of the study area. The upper 550 ft (165 m) are similar to the shallow upper Gerster deposits preserved only at the Confusion Range. 68

Brachiopod data (Wardlaw, 1974b) supports the above litho- logic correlation, as does conodont distribution {Figs. 17

& 18) .

The lower 600 ft (180 m) of the section may be equiv­ alent in age to the Plympton and possibly Kaibab Formations of the study area. Lithologically the 100 ft of cherty dolomite is similar to Plympton rocks and may represent a northward progradation of the Plympton tidal flat into the southern margin of the Phosphoria Basin. The remainder of the section contains thick carbonate units, suggesting that northeastern Nevada experienced more continuous marine sub­ mergence during Plympton time than the study area to the south. Brachiopod faunas of this interval include Thamnosia depressa, a brachiopod typical of the Grandeur member of the Park City Formation (Wardlaw, per. com.). Conodonts include Anchignathodus n. sp. (known from both the Kaibab and Plympton Formations), Neogondolella n. sp. (previously recovered in this study only from the Gerster Formation, but reported by Behnken, 1975a, from the Plympton Formation) and poorly preserved ramiform elements. These elements do not appear to belong in the genus Ellisonia, but bear a resemblance to other poorly preserved ramiform elements recovered by Baird (per. com.) from the Kaibab Formation. 69 The affinity of these elements is uncertain. They are unknown from Gerster deposits.

Similarities between conodont distribution in the

Gerster Formation of the study area and at Montello suggest that the depositional environment of northeastern Nevada was not appreciably different than that of the study area during Gerster time. The close proximity of the last occur­ rence of Neospathodus arcucristatus and the first occurrence of Neospathodus diverqens in the Montello section lends support to Behnken's (1975a) zonation of the Gerster For­ mation and suggests that conodont Zone C of this study may be artificial.

Conodont distribution in Plympton equivalent rocks at

Montello bears much less resemblance to what is presently known about Plympton deposits in the study area. The presence of Neogondolella n. sp. is probably due to eco- logic factors (possibly deeper water) at Montello. The absence of Ellisonia n. sp. and Neospathodus arcucristatus is inexplicable. Additional study of the Plympton Formation and age equivalent rocks in Nevada, Utah and Idaho is badly needed. AGE AND CORRELATION OF THE GERSTER FORMATION

Age - The age of the Gerster Formation has been variously reported as Wordian and/or Capitanian on the basis of its brachiopod fauna, conodont content and stratigraphic posi­ tion (see Introduction). The only detailed study of Ger­ ster brachiopod faunas (Wardlaw, 1974a, 1974b) supports a Wordian age for the Gerster Formation.

Conodont evidence is not in disagreement with the

Wordian age proposed by Wardlaw. Clark and Behnken (1971) have theorized a Capitanian age for at least the upper part of the Gerster Formation based on the fact that upper Ger­ ster type brachiopods occur also in the Owens Valley For­ mation of California in association with the key Capi­ tanian ammonoid Timorites and based on the occurrence in the upper Gerster Formation of conodonts "that represent the same species as those reported from the German Zech- stein I (Capitanian or younger)" (Clark and Behnken, 1971, p. 421). In the latter case, Clark and Behnken refer most significantly to Neospathodus divergens (Bender fit Stoppel). 71

The brachiopod correlations cited by Clark and Behnken are based on the 11 Punctospirifer pulchra" fauna widely identi­

fied from the Upper Permian of western North America

(Williams, 1959; Yochelson, 1968). In fact, the author knows of no detailed study of the brachiopods in the Owens

Valley Formation and they may not even be correlative with the Gerster brachiopods. The "Punctospir ifer pulchra" fauna of the Gerster Formation has been studied in detail only by Wardlaw (1974a, 1974b) and he considered it to be

Wordian. Conodonts have not been reported from the Owens

Valley Formation, therefore no conodont comparison can be made with the Gerster Formation. Neospathodus divergens

(Bender & Stoppel) has been recovered from both the Zech- stein I of Germany and the upper Gerster Formation, how­ ever the age of the Zechstein I is by no means firmly established as "Capitanian or younger". Brinkman (1969,

Permian correlation chart) indicates that the Lower Zech­ stein deposits correlate with the Wordian of West Texas.

Clark and Behnken's Capitanian age assignment for the Ger­ ster Formation is probably too young, when compared with the studies of Wardlaw.

Information on Permian conodont distribution is still insufficient to permit an age determination for the Gerster Formation, but the known range of Gerster species can be analyzed. Neospathodus arcucristatus Clark and Behnken has been recovered from the Concha and Rainvalley Formations of southeastern Arizona (Butler, 1972, 1973). The age of these formations is given as Upper Leonardian on the basis of brachiopods (Dunbar and others, 1960) and corroborated on the basis of the conodont species Neostreptoqnathodus sulcoplicatus (Baird, 1975). Neospathodus diverqens

(Bender & Stoppel) is known only from the Zechstein I of

Germany (Bender & Stoppel, 1965), the age of which is cer­ tainly Guadalupian, possibly restricted to Wordian (Brink- mann, 1969). Neither species of Neospathodus has been identified in West Texas, although a few nondiagnostic elements of the associated genus Ellisonia have been recov­ ered there (Behnken, 1972; Croft, 1972). As reported by

Behnken (1972, 1975a) and Croft (1972), Anchiqnathodus n. sp. ranges from the South Wells Member of the Cherry

Canyon Formation (Wordian, Dunbar and others, I960; Behnken,

1972, 1975a) through the Radar Member of the Bell Canyon

Formation (Capitanian, Dunbar and others, I960; Behnken,

1972, 1975a). Butler (1972, 1973) describes it from the

Concha and Rainvalley Formations of Arizona (Upper Leonard­ ian) and Baird (1975) and Baird & Collinson (1975) from the 73

Kaibab and Plympton Formations (Upper Leonardian, Lower

Wordian, Dunbar and others, 1960; Baird, 1975; Baird &

Collinson, 1975) in the study area. Xaniognathus tribulosus

(Clark & Ethington) is reported by Behnken (1972, 1975a) and

Croft (1972) from the Cherry Canyon and Bell Canyon Forma­ tions (Wordian and Capitanian) of West Texas and by Young- quist and others (1951) from the Meade Peak Member of the

Phosphoria Formation (Upper Leonardian or Lower Wordian,

Dunbar and others, 1960). Neogondolella n. sp. is unknown outside the study area. Its previous identification as

Neogondolella rosenkrantzi (Bender & Stoppel) by Clark and Behnken (1971) is incorrect. Analysis of these ranges

indicates that conodonts known from the upper Plympton limestone units and the Gerster Formation have been recov­ ered in other areas from rocks ranging in age from Upper

Leonardian to Capitanian. The age of the Gerster Forma­ tion could lie anywhere within this range, thus it is not incompatible with the Wordian age suggested by Wardlaw's brachiopod studies (1974a, 1974b).

Correlations with other formations - The Gerster For­ mation has been correlated with many other formations on the basis of megafossils (Yochelson, 1968). The purpose of this section is to suggest correlations with other 74 formations containing described Permian conodonts.

The Gerster Formation is probably correlative with the Bell Canyon Formation in West Texas on the basis of the mutual occurrence of Xaniognathus tribulosus. Bender and

Stoppel (1965) have described a conodont fauna from tecton-

ically isolated Permian limestone blocks in Sicily that may m contain nearly all elements found in the Gerster Formation.

Xaniognathus tribulosus appears to be represented, as well as Ellisonia type ramiform elements and a single specimen

(Spathognathodus galeatus of Bender & Stoppel) that may represent Neospathodus arcucristatus Clark & Behnken. So- called juvenile forms of Bender and Stoppel's Gnathodus sicilianus may in fact be like Anchignathodus n. sp. of this paper. The age of the Sicilian deposits is given as

Wordian by Miller (1933) on the basis of ammonoids, but their structural relationships are complex and their age is as yet uncertain. The Gerster Formation and the Zechstein

Limestone of Germany (Bender & Stoppel, 1965) both contain

Neospathodus divergens (Bender & Stoppel), suggesting a possible correlation between the upper Gerster and Zechstein

1; however, the range of N. divergens is as yet uncertain.

Although both the Gerster Formation and the Concha and

Rainvalley Formations contain Neospathodus arcucristatus, 75

Ellisonia n. sp., and Anchignathodus n. sp., the Concha and Rainvalley Formations are considered older (Upper

Leonardian) than the Gerster Formation because ranging throughout them is Neostreptognathodus sulcoplicatus, a conodont species that is confined to the upper Kaibab and lower Plympton Formations (Baird, 1975; Baird & Collinson,

1975). SYSTEMATIC PALEONTOLOGY

307 productive samples from the Upper Plympton and

Gerster Formations in the study area and from Upper Permian

strata at Montello have yielded 5,386 conodont elements

representing 21 form species. Although many of these form

species have been previously described, all but six are

recognized as components of multielement apparatuses of

Guadalupian age for the first time. These elements are

assigned to 6 species of 5 unimembrate and multielement

conodont genera.

Conodont descriptive terminology is currently in a

state of flux. Objective morphologic terms are needed to describe concisely the major shape categories of discrete

conodont elements. Multielement apparatuses of various types or plans have been identified (i.e., Rhodes (in Hass,

1962); Klapper & Phillip, 1971; Jeppsson, 1971), but a uni­ fying terminology for apparatus architecture is lacking.

In addition, a method designating homologous positions within apparatus types is needed. Hopefully, publication of an updated conodont apparatus terminology in the revised

76 77

Volume W of the Treatise of Invertebrate Paleontology will solve many of the existing problems.

To date, most authors have employed contractions of familiar or generic names in describing shape categories.

Although this custom is somewhat subjective and possibly confusing (a bilaterally symmetrical element might be trichonodellan in Ordovician age samples, but ellisonian or roundyan in samples of Permian age), it will be employed in the following discussions as the best solution currently available. Apparatus types and/or positions within an ap­ paratus have recently been identified by numbers or let­ ters (i.e., Rhodes (in Hass, 1962); Klapper & Phillip,

1971; Jeppsson, 1971; Sweet, 1970a, 1970b; von Bitter,

1972; Baesemann, 1973) . The alphabetical position desig­ nations of Sweet (1970a, 1970b) were clearly established for multielement apparatuses similar to those described in this report. These designations were tentative, however

(Sweet, 1970b, p. 225) and may now be confusing in view of increased knowledge concerning possible homologous ele­ ments. The author has chosen to employ the alphabetical terminology of Klapper & Phillip (1971) and Baesemann

(1973) for Type 1 conodont apparatuses. Their terminology is familiar and permits recognition of homologous structures within the apparatuses under study without the

confusion of rearranging Sweet's (1970a) terms or estab­

lishing yet another system. The choice of Type 1 alpha­ betical terminology does not imply that all multielement apparatuses under study are based upon the Type 1 plan.

Ellisonia n. sp. and Xaniognathus tribulosus may be suf­

ficiently distinct to warrant inclusion in different, as yet undescribed, types. Further studies should clarify this matter. Genus ANCHIGNATHODUS Sweet, 1970a

Type Species: Anchignathodus typicalis Sweet, 1970a

Diagnosis: A group of conodont species characterized by a six member apparatus in which morphologically inter- gradational, evolutionarily conservative ramiform elements occupied A and N positions, an anchignathodontiform element occupied the P position and an ozarkodiniform element occu­ pied the 0 position. Ramiform elements are compressed and delicate in appearance, and bear small, needlelike den­ ticles arranged in crude hindeodelloid series. In asym­ metrical ramiform elements, one process is usually 4 or more times the length of the other and the shorter process is characterized by a large distal denticle that projects downward. Bilaterally symmetrical elements lack a poste­ rior process. Anchignathodontiform elements appear to have evolved most rapidly and serve to distinguish species.

Remarks: Sweet (1970a) erected Anchiqnathodus to in­ clude paired, individually asymmetrical elements of a single morphologic type, which previously had been includ­ ed in Spathognathodus. Species assigned by Sweet (1970b) to Anch ignathodus range in age from Lower Carboniferous 79 80

(uppermost Kinderhookian) to basal Triassic. Most subse­ quent studies of Upper Pennsylvanian and Permian conodont faunas (Perlmutter, 1971; Behnken, 1972, 1975a; Butler,

1972; Croft, 1972; von Bitter, 1972; Merrill, 1973; Wind,

1973) have agreed with Sweet's original diagnosis of

Anchignathodus as a single-element genus. Analysis of faunas reported in the above papers (except in that by

Behnken, who probably did not describe all long-ranging ramiform elements present; and Merrill, who was dealing only with Spathognathodus) indicates that ramiform elements of the type assigned by Sweet (1970a, 1970b) to Ellisonia teicherti do occur in close association with elements of

Anchignathodus. This close association has led Sweet,

(per. com.) to suggest that anchignathodontiform elements may not represent single-element species, but may have occupied P positions in the apparatus of a multielement species. Baesemann (1973) has actually erected three multielement species based on a ramiform series, an ozark- odiniform element of E. teicherti type and an anchignath- odontiform element. He referred these species to Ozark- odina, however.

Differences in the range and abundance of anchig­ nathodont if orm elements compared to possibly associated 81

ramiform elements have been cited (Sweet, 1970a, 1970b;

von Bitter, 1972; Merrill, 1973) as evidence that species

of Anchignathodus do not belong in a multielement appa­

ratus. There are, however, other possible causes for the

discrepancies in range or abundance. The proposed ramiform

elements of Anch ignathod us (Ellisonia teicherti type ele­

ments) are very small and delicate and may be preserved in

reduced numbers (or not at all) in some samples in which

the less fragile anchignathodontiform elements are present.

Low conodont-element abundance, typical of many Permian

deposits, may prevent accurate analysis of multielement

apparatus composition. Further work will be needed to

prove or disprove clearly the concept of Anch ignathodus as a multielement genus.

The ramiform elements of Anchignathodus are distin> guished from those of other multielement conodont species described in this study by (1) lack of a posterior process on the A^ element (2) closely spaced denticles of two or more distinct sizes arranged in hindeodelloid series (3) generally smaller size of elements (4) uniform distribu­ tion of white matter in upper portion of all denticles.

Several multielement genera and species belonging,

in the author's opinion, in the multielement genus 82

Anchignathodus have been described. Ellisonia teicherti

Sweet (1970a, 1970b), E. sp. t Croft (1972), and E. teichert i Sweet? of von Bitter (1972) were all established on the basis of ramiform assemblages and a single O ele­ ment, but are associated with one or more anchignathodonti-

form elements, which were probably part of their skeletal apparatus. E. teicherti appears to be associated with A. typicalis Sweet (1970a), Croft's Ellisonia sp. t with

Anchignathodus sp. ? a Croft (1972) , and 12. teicherti

Sweet? of von Bitter with A. minutus (Ellison, 1941) , A. edentulus von Bitter (1972) (of which the author regards

Spathognathodus ohioensis Merrill, 1973, as a junior syn­ onym) and A. moorei von Bitter (1972) (of which the author regards Spathognathodus n. sp. A of Merrill, 1973, and the

P element of Ozarkodina n. sp. B of Baesemann, 1973, as

junior synonyms).

Three multielement apparatuses including ramiform elements, an ozarkodiniform element and an anchignathodon- tiform element have also been described. Baesemann (1973) distinguishes three multielement species on the basis of differences in the anchignathodontiform element. He assigns these multielement species to Ozarkodina Branson and Mehl (1933) in the expanded sense of Walliser (1964), Lindstrom (1970), Klapper and Philip (1971). The author disagrees with Baesemann's generic assignment because multielement Ozarkodina includes a spathognathodontiform rather than an anchignathodontiform element in the P posi­ tion and possesses an A element with a posterior process in contrast to Pennsylvanian, Permian and Triassic forms that lack a posterior process. Other Ozarkodina ramiform elements may be distinguished from those of Anchignathodus by fewer and larger denticles and the lack of development of an enlarged, downwardly projected, terminal, anterior denticle. While species of Ozarkodina are clearly similar to those of Anchignathodus, the persistent distinctions between their elements argues for their subdivision into separate genera.

The author places multielement conodont species of the Ellisonia teicherti and Anchignathodus typicalis types in Anchignathodus, because the type species of the form genus Anchignathodus is clearly an element in the appa­ ratus of the type species of the newly expanded multi­ element genus. 64 Anch ignathodus n. sp.

PI. 1, Figs. 1-5, 8 r PI. 3, Figs. 12 & 19

Anchignathodus n. sp. Baird, 1975, p. 23-27, PI. 1, Figs.

17-23.

?Anchignathodus ? sp. Baird, 1975, p. 27-30, PI. 1,

Figs. 1-4

Diagnosis: six member apparatus? P element, anchig­

nathodont if orm? O element, ozarkodiniform? N element, neo-

prioniodontiform? A^ element, hindeodelliform? , unnamed

form genus? A^, hindeodontiform.

P element

PI. 1, Fig. 4

Anch ignathodus typicalis Sweet of Behnken, 1972,

p. 113-114, PI. 2, Fig. 20? 1975a, p. 297-298, PI. 2,

Fig. 12.

Anch ignathodus sp. C. Butler, 1972, p. 78, Pi. 2, Fig. 2;

PI. 12, Figs. 12-21? PI. 15, Figs. 17-20 & 23-29.

Anchignathodus sp. E Butler, 1972, p. 79-80, Pi. 15,

Fig. 30.

Anchignathodus sp. b Croft, 1972, p. 12, Pi. 1, Figs. 3-10.

Anchignathodus n. sp., Pb element of Baird, 1975,

p. 23-25, PI. 1, Fig. 18. 85

?Anchignathodus sp. D Butler, 1972, p. 79, PI. 12,

Figs. 22 & 23r Pi. 15, Figs. 9-11.

Description: Slightly arched, individually asym­ metrical, paired, anchignathodontiform elements. Anterior process surmounted by laterally compressed, subtriangular to delta-shaped, pointed cusp. Anterior margin of cusp forms angle of about 50 degrees with basal margin of ele­ ment. Posterior process bears up to 8 robust to slightly compressed, sharply pointed denticles, the proximal 4 to 5 of which decrease gradually in size away from the cusp, and the distal 3 of which decrease sharply to the basal margin. Posterior denticles fused up to three-fourths of their height. White matter present in upper one-half to three-fourths of posterior denticles and in posterior half of cusp. Basal cavity broadly flared, tapering slightly at distal end of posterior process. Narrow basal groove extends from anterior portion of basal cavity along under­ side of anterior process.

Remarks: All specimens of the P element of Anchig­ nathodus n. sp. in our collections are broken, generally lacking the cusp and most of the expanded attachment sur­ face. Comparison with better-preserved material from the

Kaibab collections of Baird (1975a) indicates that Kaibab 86 and Upper Plympton Anch ignathodus examples are members of the same species. The P element of Anchignathodus n. sp. has been described in part from Baird's superior material.

Material: 60 specimens from the Plympton Formation at the Medicine Range, Butte Mountains, Cherry Creek and

Gold Hill sections and from Plympton equivalent rocks at

Montello.

Occurrence: Plympton Formation in eastern Nevada and western Utah; Kaibab Formation in Utah, Nevada and

Arizona (Baird, 1975); Concha and Rainvalley Formations,

Arizona (Butler, 1972); South Wells Member of the Cherry

Canyon Formation through the Radar Member of the Bell

Canyon Formation, West Texas Permian Basin (Behnken, 1972,

1975a; Croft, 1972).

Repository: Figured hypotype: O.S.U. 31317 (Pi. 1,

Fig. 4).

O element

PI. 1, Figs. 2 & 3

Neospathodus sp. A Butler, 1972, p. 101, Pi. 12, Fig. 6;

Pi. 15, Figs. 7 & 8.

Anch ignathodus n. sp.. Pa element of Baird, 1975, p. 25,

Pi. 1, Fig. 19. 87 ?Anchignathodus ? sp., Pa element of Baird, 1975,

p. 27-28, PI. 1, Pig. 4.

Description; Moderately arched, individually asym­ metrical, paired ozarkodiniform elements with short, in­ wardly and basally deflected anterior process and posterior process 3 to 4 times length of anterior process, bowed in distal third of length. Cusp stout, laterally compressed,

2 to 3 times width of other denticles. Anterior process bears 1 or more denticles of equal size, larger than pos­ terior denticles, about one-third the size of cusp. Pos­ terior process bears at least 8 to 12 small denticles of equal size. All denticles nearly erect, fused for about one-half of their height. White matter evenly distributed in upper one-half to three-fourths of all denticles. Large specimens display posterior denticle enlargement resulting from incorporation of 2 or more tiny denticles into one larger denticle. Basal cavity slightly flared and very deep beneath cusp; attachment surface extended as broad groove beneath anterior and posterior processes.

Remarks; 0 elements of Anchignathodus n. sp. are readily distinguishable from 0 elements of Ellisonia n. sp. by their short, downwardly deflected anterior process, laterally compressed and closely spaced denticles, uniform 88 distribution of white matter and overall size. They may be distinguished from 0 elements of xaniognathus tribulosus by their short, laterally curved anterior process, lat­ erally compressed, blunt denticles and more prominently flared basal cavity.

Material: 5 specimens, all from Montello, Nevada.

Occurrence: Plympton equivalent rocks in north­ eastern Nevada; Concha and Rainvalley Formations, Arizona

(Butler, 1972a).

Repository: Figured hypotypes: O.S.U. 31315 (Pi. 1,

Fig. 2), 31316 (Pi. 1, Fig. 3).

N element

PI. 3, Figs. 12 & 19

Anchignathodus n. sp., M element of Baird, 1975,

p. 25-26, PI. 1, Fig. 20

Description: Paired, individually asymmetrical, neoprioniodontiform elements with short, strongly curved anterior process and short posterior process. Elements

J-shaped in top view. Terminal anterior denticle greatly enlarged and projected downward. Posterior process short, bearing 3 to 4 needlelike denticles. Cusp indistinguish­ able from other denticles of the processes. White matter 89 evenly distributed through upper one-half to three-fourths of all denticles. Attachment surface expanded beneath cusp and proximal portion of anterior process to form flared basal cavity, extends as narrow groove along entire length of both processes.

Remarks: All specimens in the collections at hand display broken posterior processes. In this state, they may be mistaken for the lonchodiniform (N) element of

Ellisonia n. sp. Recognition of the enlarged denticle as a terminal anterior denticle and not a cusp eliminates the possibility of confusion between the two elements.

Material: 7 specimens from Plympton equivalent rocks at Montello, Nevada.

Occurrence: Plympton age rocks in northeastern

Nevada; Kaibab Formation in Utah, Nevada and Arizona

(Baird, 1975).

Repository: Figured hypotypes: O.S.U. 31320

(PI. 3, Fig. 12), 31321 (PI. 3, Fig. 19).

element

PI. 1, Fig. 5

Hindeodella triassica Muller of Butler, 1972, p. 87-88,

PI. 13, Figs. 2 & 3; PI. 14, Figs. 11 & 12; PI. 16,

Fig. 36. 90

Ellisonia sp. t, LB element of Croft, 1972, p. 15, PI. 2,

Figs. 10-12.

Anchignathodus n. sp., Sc element of Baird, 1975, p. 27,

PI. 1, Figs. 22 & 23.

?Hindeodella sp. a Bender & Stoppel, 1965, p. 344-345,

PI. 15, Fig. 6.

?Anchignathodus ? sp. , Sc element of Baird, 1975,

p. 29-30, PI. 1, Figs. 1 & 2.

Description: Moderately arched, individually asym­ metrical, paired hindeodelliform elements with markedly unequal processes. Cusp stout, laterally compressed, bears sharp anterior and posterior costae from which pro­ cesses are produced. Anterior process stout, postero- laterally curved. This process bears 1 or 2 discrete den­ ticles, the distalmost denticle basally projected and up to three-fourths the size of the cusp. Posterior process straight, 4 or more times length of anterior process, bears numerous (8 to 16) small, discrete, needlelike den­ ticles arranged in hindeodelloid series. Germ denticles frequently incorporated into fewer, larger denticles in larger forms. White matter distribution even, present in three-fourths of the height of all denticles. Attachment surface slightly flared and projected downward beneath 91 cusp and anterior process, extended as basal groove be­ neath posterior process.

Remarks: The A^ element of Anchignathodus n. sp.

is readily distinguished from the A^ element of Ellisonia n. sp. by its smaller size, more closely spaced and needlelike denticles, even distribution of white matter and short, basally deflected anterior process. It is separated from the A^ element of Xaniognathus tribulosus by its straight posterior process and short anterior pro­ cess, small denticles of unequal size, and development of white matter only in denticles.

Material: 7 specimens from Plympton equivalent rocks at Montello, Nevada.

Occurrence: Kaibab and Plympton Formations, eastern

Nevada and western Utah {Baird, 1975): Concha and Rain­ valley Formations of Arizona (Butler, 1972); Pinery Member of Bell Canyon Formation in West Texas (Croft, 1972);

?Middle Permian of Sicily (Bender & Stoppel, 1965).

Repository: Figured hypotype: O.S.U. 31318 (PI. 1,

Fig. 5). element

PI. 1, Fig. 8

Anchignathodus n. sp.# Sb element of Baird, 1975,

p. 26-27, PI. 1, Fig. 21.

Description: Slightly arched, individually asym­ metrical, paired elements with two processes of moderately unequal length produced from faint anterior and posterior costae on the cusp. Cusp laterally compressed, 4 to 5 times height of process denticles. Posterior process slightly curved laterally and deflected downward in distal portion, bears up to 11 needlelike, discrete denticles arranged in crude hindeodelloid series. Anterior process curved laterally in distal portion, deflected upward, bears

8 discrete, needlelike denticles, the 2 distal denticles are very large, nearly equalling cusp in size. Denticles of distal margins of both processes reclined slightly toward cusp, cusp slightly proclined. White matter dis­

tribution and basal cavity development like A^ elements.

Remarks: The A^ element of Anchignathodus n. sp.

is distinguished from the A^ element of Ellisonia n. sp. by its needlelike denticles, upwardly deflected anterior

process and the development of large distal denticles on

the anterior process. It also lacks the "hook" that char­

acterizes the posterior process of E. n. sp. It is 93 completely different from the A^ element of Xaniognathus tribulosus, which is a lonchodiniform element with short anterolateral processes and a posteriorly flared lip.

Material: 9 specimens from Plympton equivalent rocks at Montello, Nevada.

Occurrence: Kaibab and Plympton Formations, eastern

Nevada and western Utah (Baird, 1975).

Repository: Figured hypotype: O.S.U. 31319 (Pi. 1,

Fig. 8).

A^ element

PI. 1, Fig. 1

Anchignathodus n. sp., Sa element of Baird, 1975, p. 26,

PI. 1, Fig. 17.

?Anchignathodus ? sp., Sa element of Baird, 1975,

p. 28-29, PI. 1, Fig. 3.

Description: Symmetrical hindeodelliform element with short, posteriorly curved and slightly basally deflected lateral processes. Posterior process absent.

Central cusp anteroposteriorly compressed, 2 to 3 times height of process denticles, bears faint lateral costae.

Lateral processes display at least 6 needlelike, discrete denticles arranged in crude hindeodelloid series. White 94 matter evenly distributed through upper three-fourths of all denticles. Attachment surface a slightly expanded basal cavity beneath cusp, extends as narrow basal groove into lateral processes.

Remarks: One broken specimen of the element was identified from Plympton equivalent rocks at Montello,

Nevada. It is readily distinguished from the A^ elements of other multielement species in our collections by the lack of a posterior process.

Material: 1 specimen from Plympton equivalent rocks at Montello, Nevada.

Occurrence: Kaibab and Plympton Formations, eastern

Nevada and western Utah {Baird, 1975) .

Repository: Figured hypotype: O.S.U. 31314 (PI. 1,

Fig. 1).

Anchignathodus n. sp. is distinguished from other described species of Anchignathodus primarily on the basis of differences in the P element. Merrill {1973, p. 293-295) has recognized three lineages of Spathognathodontiform elements. One, the Spathognathodus coloradoensis line, includes the elements of Anch ignathodus moorei von Bitter

{=Spathognathodus n. sp. A Merrill) and A. edentulus von

Bitter (=55. ohioensis Merrill). These anchignathodontiforra elements are rare in comparison to the more abundant anchignathodontiform elements of the Anch ignathodus minutus-A. typicalis line, and are readily separated by

shape, smaller size and denticulation. P elements of

moore1 lack a prominent delta-shaped anterior denticle,

display a sharp decrease in denticle size posterior to the

large anterior denticles followed by an increase in size

in the distal posterior denticles, have nearly vertical anterior and posterior margins and possess a basal cavity

that extends beyond the distal end of the posterior blade.

P elements of A. edentulus lack denticles on the posterior

one-third to one-half of the blade. This portion of the blade bears a sharp edged crest that is continuous in height with the preceding anterior denticles. Basal cavity and anterior and posterior margins are like those of A. moorei. It is possible that the A. moorei and A. edentulus

lineage is not closely related to the A. minutus-A. typicalis lineage, but represents homeomorphic development

in a different group (Merrill, 1973) .

The P element of the Anch ignathodus minutus- h ' typicalis lineage (in which Anch ignathodus n. sp. be­

longs) is characterized by a subtriangular to delta-shaped

anterior crest composed of discrete, fused, or overgrown denticles, a gradual decrease in denticle height posterior to the crest and a broadly flaring attachment surface that does not extend beyond the distal end of the posterior blade. Species within this lineage are distinguished by

P elements that show differences in length to width ratio and denticulation, P elements of A. n. sp. are distin­ guished from those of A. minutus by a gradual decrease in denticle size proximal to the anterior denticle and by a smaller length to width ratio (approximately 2 to 2.5 times as long as wide as compared to 3 times as long as wide for A. minutus). In P elements of A. typicalis, den­ ticles behind the anterior crest may be distinguished from each other for nearly their entire height, whereas in P elements of A. n. sp. the lower two-thirds of each denticle is fused into an indistinguishable ride on the upper sur­ face of the flared basal cavity sheath. In addition, den­ ticles of the P element of A. n. sp. are more robust and less compressed than those of the P element of A. typicalis and the apex of the basal cavity in A. n. sp. elements is sharply pointed rather than rounded off. The P element of

Anch ignathodus julfens is Sweet (in Teichert, Kummel & Sweet,

1973) is separated from the P element of A. n. sp. b y the

"hump" or bulge formed in distal denticles of the posterior 97 process. The P element of A. n. sp. is separated from the

P element of Croft's Anch ignathodus sp. a (which may be identical to Spathognathodus n. sp. Clark & Ethington, 1962) by a less expanded basal cavity, larger, more delta-shaped anterior denticle and higher posterior denticles in relation to the height of the flared attachment surface. Genus ELLISONIA Muller, 1956

Type Species: Ellisonia triassica Muller, 1956

Description: A group of conodont species character­ ised by a six member apparatus consisting of morpholog­ ically intergradational ramiform elements occupying the

A, N and possibly P positions and an ozarkodiniform element' occupying the 0 position. The distinctive morphologic elements within the genus are typically so intergrada- tional that it is extremely difficult to determine element position within the apparatus. All elements are large and robust, with rounded, peg-like denticles. The A^ element bears a long, straight, denticulated posterior process. In some species, the ramiform elements display inverted basal margins.

Remarks: Sweet (3 970a, 1970b) expanded the concept of the form genus Ellisonia to that of a multielement genus, one species of which includes the types of Ellisonia triassica Muller, 1956. Sweet (1970b) included seven multielement species from uppermost Permian and Lower Tri- assic rocks within expanded Ellisonia, but indicated that

98 99 similar multielement skeletal plans occurred in conodonts ranging in age from Ordovician to Triassic and that his preliminary concept of Ellisonia would probably require further refining. Subsequently Sweet (1973a) sug­ gested that multielement species originally assigned by him to Ellisonia may be divisible into three main groups at the generic level (Group I=Ellisonia sensu stricto;

Group II=Cypridodella in a multielement sense; Group 111= species similar to E. teicherti, possible generic name not suggested). At present, work by Sweet and others continues on these groups (Sweet, per. com.). Species now assigned to Ellison ia sensu stricto are troublesome because of the morphologic similarities between their various elements.

Further study and refinement are required. Pending a better understanding of Ellisonia, all distinctive element types from the Gerster Formation collections have been described as thoroughly as possible. These elements have then been assigned to a defensible apparatus position, but with the reservation that some of these assignments may require change in the future.

Three multielement Ellisonia species have been des­ cribed prior to this paper, Ellisonia triassica Muller of

Sweet (1970a, 1970b), Ellisonia festiva (Bender and Stoppel) 100 of Croft (1972) and Ellisonia pretriassica Wind (1973).

E. triassica sensu Sweet is based on four rajniform elements,

U, LA, LB and LF (A^# N, A^, and A^ or 0 of present ter­ minology) . Wind's E. pretriassica is described from the same four elements. E. festiva sensu Croft includes U,

LA and LB (A^/ N and A^) elements, but only 28 specimens were recovered from his samples and they are poorly pre­ served.

Form taxa clearly belonging in Ellisonia are known from the Permian and Lower Triassic rocks of North America,

Europe, and Asia. The ramiform elements of species of this genus are frequently undescribed, however, as they have been regarded as long-ranging forms of little stratigraphic value. Thus, a great deal of additional information, both from known collections and from new studies, must be ana­ lyzed before the range of the genus can be well established.

Ellisonia n. sp.

PI. 1, Figs. 16-18, 20-23

PI. 3, Figs. 5-8, 10, 11, 14-18

?Ellisonia festiva (Bender & Stoppel) of Croft, 1972,

p . 15-17, PI. 1, Figs. 14-16f Pi. 2, Figs. 5-8; of

Baird, 1975, p. 30-34, PI. II, Figs. 9-17. 101

Diagnosis: probable six member apparatus; P element, not recovered from the collections at hand; 0 element, ozarkodiniform; N element, lonchodiniform; A^ element, hindeodelliform; element, neoplectospathodontiform; A^ element, hibbardelliform.

P element

No elements regarded by the author as occupants of the P position were recovered. It is possible that Neo- spathodus arcucristatus Clark & Behnken represents the

P element of Ellisonia n. sp., but this is uncertain (see discussion under N. arcucristatus).

O element

PI. 1, Pig. 16

Description: Slightly arched, asymmetrical, paired, ozarkodiniform elements with basal cavity expanded poster- olaterally. Denticles discrete, slightly compressed and reclined. One prominent cusp at apex of basal cavity with at least 4 smaller anterior denticles and 7 or more smaller posterior denticles. Distal denticle on anterior process sometimes larger than remaining anterior denticles. White matter distribution irregular, ranging from virtually none 102 to three-fourths of denticle height. Viewed from the base, the basal margin is irregularly sinuous. Distal ends of both processes may curve inward, curvature most pronounced on anterior process. Anterior process shorter than pos­ terior process. Basal cavity extended as narrow groove approximately three-fourths length of both processes.

Remarks: Morphologic similarities between 0, A^/ and

A^ elements may be striking; however, they can generally be separated by the following criteria: 0 from A^ (1) den­ ticles of 0 element less strongly reclined. (2) 0 element lacks prominent posterior denticle situated above flared basal groove. (3) 0 element lacks strong downward flexure of posterior process. 0 from A^ (1) O element arched, not straight. (2) greater expansion of basal cavity in O ele­ ment. (3) less white matter in A^ elements.

Material: 128 elements recovered from all measured

Gerster Formation sections in the study area and at Montello.

Occurrence: Gerster Formation, eastern Nevada and western Utah.

Repository: Figured hypotype: O.S.U. 31323 (PI. 1,

Fig. 16). 103 N element

PI. 1, Fig. 23; PI. 3, Figs. 8, 11, 15, 16, 18

Lonchodina festiva Bender & Stoppel of Clark and Behnken,

1971, Pi. 2, Fig. 9; of Butler, 1972, p. 94-95,

PI. 13, Figs. 22 & 23> PI. 14, Fig. 23.

Lonchodina inflata Bender & Stoppel of Clark and Behnken,

1971, PI. 2, Fig. 3.

Lonchodina muelleri Tatge of Butler, 1972, p. 96-97, Pi. 13,

Figs. 1 & 19.

?Lonchodina festiva Bender & Stoppel, 1965, p. 345-346,

Pi. 15, Figs. 9 & 10.

?Lonchodina inflata Bender & Stoppel, 1965, p. 346, PI. 15,

Figs. 8 a-c; PI. 16, Figs. 18 a-c; of Szaniawski,

1969, p. 330-331, Pi. 1, Figs. 5 & 6; of Butler,

1972, p. 95-96, Pi. 14, Figs. 21 & 24.

?Lonchodina cf. inflata Bender & Stoppel, 1965, p. 346—347,

PI. 15, Fig. 11; PI. 16, Fig. 24.

?Lonchodina muelleri Tatge of Bender & Stoppel, 1965,

p. 347, PI. 15, Fig. 12 (not) Pi. 15, Figs. 13 & 14.

?Ellisonia festiva (Bender & Stoppel), LA element of Croft,

1972, p. 15-17, Pi. 2, Fig. 5; Sa^ element of Baird,

1975, p. 31-32, PI. II, Fig. 10. 104

Description: Paired, asymmetrical elements with subequal to moderately unequal anterolateral processes and a reclined cusp with a midposterior carina, the basal por­ tion of which is expanded to produce a short, adenticulate, symmetrical or slightly laterally deflected posterior lip.

Stout, peg-like, slightly reclined cusp is flanked on each anterolateral process by 3 to 5 discrete, posteriorly in­ clined denticles less than half cusp height. Cusp possesses sharp anterolateral costae. White matter distribution ranges from none to three-fourths of denticle height.

Anterolateral processes projected downward and curved posteriorly. Basal pit developed beneath posterior lip, extends as narrow groove into anterolateral processes.

Remarks: The symmetry of both the N and elements may be interpreted as transitional between the A^ and A^ elements. On the basis of symmetry, either element could be placed in the form transition series. In addition, the peg-like denticle shape and poor white matter development characteristic of N elements (but less so of A^ elements) is typical of A^ and A^ elements in Ellisonia n, sp. Thus, the author's first impulse was to place lonchodiniform elements in the A^ position. Very similar elements do indeed fill the A2 position in other multielement conodont 105 genera (Ordovician Plectodina and Oulodus, for example).

However, work on Ordovician and Silurian Prioniodinacea

(Sweet & Schonlaub, in press), from which Ellisonia prob­ ably evolved, suggests that lonchodiniform elements of the type here described generally fit best in the N or possibly

P positions. The author follows this established practice, but notes that most elements of genera belonging in the

Prioniodinacea are symmetrically intergradational and further work may yet demonstrate that elements herein placed in the N position belong in the form transition series (or the P position, Sweet, per. com.).

Several Lonchodina form species have been established and/or identified from Upper Permian rocks. It is the author's opinion that at least some of these (see synonomy) represent essentially the same long ranging morphologic element type that is part of the multielement Ellisonia apparatus at least during Late Permian and Early Triassic time. Differences in denticle numbers and size, process length and symmetry, on which specific identifications are based, can readily result from breakage or growth stage.

Within single productive Gerster samples, elements like

I*. f est iva (Pi. 3, Pig. 18), L. inf lata (Pi. 1, Fig. 23;

PI. 3, Fig. 15) and L. muelleri (PI. 3, Pigs. 11 & 16) may 106 be found, with intergradational forms present as well.

Thus it seems likely that these forms are not indicative of separate species, but rather of intraspecific variations within the N element of Ellisonia. Further studies of Per­ mian conodonts will serve to clarify this possibility.

Permian age Ellisonia elements have been described

and illustrated from collections in the Wolfcampian of

Kansas (Wind, 1973), from the Concha and Rainvalley Forma­ tions of Arizona (Butler, 1972), from the Pinery Member of the Bell Canyon Formation in West Texas (Croft, 1972), from the Middle Permian of Sicily and the Zechstein Limestone of Germany (Bender & Stoppel, 1965), from the Upper Permian of Poland (Szaniawski, 1969), from the Salt Range in Pakis­ tan and Guryul Ravine in Kashmir (Sweet, 1970a & 1970b) and

from the Gerster Formation (Clark & Behnken, 1971).

The author has studied the collections of Sweet

(1970a, 1970b), Baird (1975), and Croft (1972). Sweet’s

(1970a, 1970b) material clearly belongs in a separate spe­ cies of Ellisonia on the basis of differences in develop­ ment of the basal margin, distribution of white matter and

smaller size; therefore, none of his elements are included

in synonomy with Ellisonia n. sp. Croft’s (1972) Ellisonia elements probably represent the same species as Ellisonia 107 n. sp., but his material is badly broken and includes fewer than 30 elements. It is included with a query.

The ramiform elements recovered from Baird's (1975) Kaibab samples are numerous, but very badly broken. Some prob­ ably represent elements of Ellisonia, others appear to belong to a separate genus. The latter elements are very similar to the unidentified ramiform elements recovered from pre-Gerster rocks at Montello, Nevada. Because of the poor preservation of ramiform elements in Baird's (1975) col­ lections, those believed conspecific with elements of

Ellisonia n. sp. are included with a query.

I have not seen material from the collections of Wind

(1973), Butler (1972), Bender & Stoppel (1965) or Szaniawski

(1969). The Ellisonia-type elements described by Wind (1973) are Wolfcampian in age, definitely much older than Ellisonia elements collected in the Gerster Formation. Without study­ ing material from the Wolfcampian, the author would hesitate to assign the Ellisonia elements described by Wind (1973) to the same species as :E. n. sp. Butler's (1972) Ellisonia material is well preserved and copiously illustrated. It appears conspecific with Ellisonia n. sp. His collections contain other conodont species also found in the Gerster

Formation (Anchignathodus n. sp., Neospathodus arcucristatus Clark & Behnken). His collecting localities are in close

proximity to Utah and Nevada. For these reasons, the

author has placed Ellisonia-type ramiform elements from

the Concha and Rainvalley Formation collections of Butler

(1972) in synonomy with the appropriate elements of

Ellisonia n. sp. Bender & Stoppel's (1965) collections

from Sicily are well illustrated and their Ellisonia-type

ramiform elements appear very similar, possibly conspe­

cific, with Ellisonia n. sp. In addition, their collec­

tions include possible examples of Neospathodus arcucris-

tatus and Anch ignathodus n. sp. Due, however, to the

author’s limited familiarity with these geographically

distant collections, I prefer to include elements of

Ellisonia type from Bender & Stoppel*s (1965) Sicilian col­

lections in synonomy with Ellisonia n. sp. only on a ques­

tionable basis. Similar arguments apply to the Zechstein

collection of Bender & Stoppel (1965) and the Polish col­

lections of Szaniawski.

The author has excluded Lonchodina muelleri Tatge of

Bender & Stoppel (1965, PI. 15, Figs. 13 & 14) because

these elements appear to be or N elements of a Xanioq-

nathus apparatus and not of Ellisonia.

Material: 229 specimens from the Upper Plympton and

Gerster Formations in the study area and from the Gerster 109

Formation at Montello, Nevada.

Occurrence: Plympton and Gerster Formations, eastern

Nevada and western Utah; Concha and Rainvalley Formations,

Arizona (Butler, 1972); ? Kaibab Formation of Utah and

Nevada (Baird, 1975); ? Pinery Member of Bell Canyon For­ mation, West Texas (Croft, 1972); ? Mid-Fermian of Sicily

(Bender & Stoppel, 1965); ? Zechstein Limestone of Germany

(Bender & Stoppel, 1965); ? Upper Permian of Poland

(Szaniawski, 1969).

Repository: Figured hypotypes: O.S.U. 31330 (Pi. 1,

Fig. 23; PI. 3, Fig. 15), 31333 (Pi. 3, Fig. 8), 31335

(PI. 3, Fig. 11), 31336 (Pi. 3, Fig. 16), 31338 (PI. 3,

Fig. 18).

element

PI. 1, Fig. 22

Hindeodella nevadensis Muller of Clark & Behnken, 1971,

PI. 2, Fig. 13; of Butler, 1972, p. 86, Pi. 12,

Figs. 1-5; Pi. 14, Figs. 15, 19, 20; PI. 16, Fig. 37.

Hindeodella sp. C Butler, 1972, p. 91-92, PI. 2, Fig. 1;

PI. 16, Fig. 33.

?Hindeodella triassica Muller of Bender & Stoppel, 1965,

p. 343-344, PI. 14, Fig. 12; PI. 15, Figs. 1-5; of X10

Szaniawski, 1969, p. 329-330, PI. 1, Figs. 9 a & b,

10, 11.

?Ellisonia festiva (Bender & Stoppel), LB element of Croft,

1972, p. 15-17, PI. 1, Fig. 14; Pi. 2, Figs. 6 & 7;

Sc element of Baird, 1975, p. 33-34, PI. II, Figs. 12,

13, 16, 17.

Description: Straight, individually asymmetrical,

paired, hindeodelliform elements with anterior process less

than one-third the length of posterior process. Denticles

discrete, stout, peg-like, subcircular to slightly com­

pressed in cross-section. Germ denticles of early growth

stages frequently incorporated into fewer, larger denticles

in adult forms. Cusp prominent, larger than any other

denticle, slightly to moderately reclined and laterally

inclined. Anterior process generally missing; but, where

preserved, may bear 3 or more denticles. Distal anterior

denticle large, one-half to two-thirds the height of cusp,

other anterior denticles small and of equal size. Posterior

process often broken within 1 or 2 denticles beyond cusp; but, when present, may bear at least 11 denticles. Posterior

process denticles increase in size distally, one or two

denticles near distal end may reach two-thirds the size of

cusp. Distal end of posterior process slightly curved Ill downward. White matter often lacking, especially in cusp.

Basal cavity very slightly expanded beneath cusp, extends as narrow basal groove throughout both processes. Appear­ ance of basal groove like that in posterior process of A^ element.

Remarks: A^ elements are almost invariably broken, the anterior process completely gone and the posterior process very short. Broken fragments may be identified, however, by the straight (non-arched) basal margin, narrow basal groove, and essentially non-flared basal cavity sur­ mounted by a prominent cusp. The large distal denticles of the posterior process are very similar in angle of inclina­ tion and general appearance to those on the posterior pro­ cess of the A^ element, but A^ elements lack the secondary expansion of the basal groove beneath these denticles that characterizes A^ elements. The similarity in denticulation of the posterior processes is an argument in favor of placing neoplectospathodontiform elements of the A^ type within the form transition series, rather than filling that position with lonchodiniform elements of the N type.

Material: 287 specimens collected from the Upper

Plympton and Gerster Formations in the study area and at

Montello, Nevada. 112 Occurrence: Upper Plympton and Gerster Formations, eastern Nevada and western Utah, Concha and Rainvalley For­ mations, Arizona (Butler, 1972) ? Pinery Member of Bell

Canyon Formation, West Texas (Croft, 1972); ? Kaibab Forma­ tion, Utah and Nevada (Baird, 1975), ? Mid-Permian of

Sicily (Bender & Stoppel, 1965)? ? Zechstein Limestone of

Germany (Bender & Stoppel, 1965)? ? Upper Permian of

Poland (Szaniawski, 1969).

Repository: Figured hypotype: O.S.U. 31329 (PI. 1,

Fig. 22).

A^ element

PI. 1, Figs. 18 & 21; Pi. 3, Fig. 14

Description: Moderately arched, individually asym­ metrical, paired neoplectospathodontiform elements with anterior process approximately one-half the length of pos­ terior process. Denticles discrete, stout, peg-like, sub- circular to slightly compressed in cross-section, cusp not markedly larger than surrounding denticles. Small den­ ticles proximal to cusp often incorporated into several large denticles in adult forms. In author's collection, anterior process bears up to 7 slightly reclined denticles, posterior process up to 9 moderately reclined ones. Dis­ tribution of white matter similar to N and A^ elements. 1X3 Anterior process deflected downward and curved laterally, posterior process projected upward for three-fourths of

length, then sharply hooked downward. Processes robust in cross-section, less flattened than other elements of appa­ ratus. Basal cavity moderately flared beneath cusp, nar­ rows but remains slightly expanded for almost entire length of both processes, secondarily flared beneath hook in pos­ terior process. 1 or 2 moderately reclined denticles, much larger than cusp, develop above the hook in the posterior process. Distalmost denticles of posterior process no larger than average posterior and anterior denticles.

Material: 108 specimens from the Upper Plympton and

Gerster Formations in the study area and at Montello,

N e v a d a .

Occurrence: Plympton and Gerster Formations, eastern

Nevada and west central Utah.

Repository: Figured hypotypes: O.S.U. 31325 (Pi. 1,

Fig. 18), 31328 (Pi. 1, Fig. 21; Pi. 3, Fig. 14).

A^ element

PI. 1, Figs. 17 & 20, Pi. 3, Figs. 5-7, 10, 17

Elllsonia triassica Muller of Clark & Behnken, 1971, PI. 2,

Fig. 4 114 Ellisonia cf. E^. triassica Muller of Butler, 1972, p. 84,

PI. 13, Fig. 25? PI. 16, Fig. 34.

Roundya n. sp. A Huckriede of Clark & Behnken, 1971, Pi. 2,

Figs. 7 & 8.

Roundya sp. C Butler, 1972, p. 109, Pi. 16, Figs. 19 & 20.

Roundya sp. D Butler, 1972, p. 110, PI. 12, Figs. 24-26.

?Roundya sp. a Bender & Stoppel, 1965, p. 350, Pi. 15,

Fig. 19.

?Roundya sp. b Bender & Stoppel, 1965, p. 350, Pi. 15,

Figs. 20 a-c.

?Hibbardella baitica Szaniawski, 1969, p. 332-333, PI. 2,

Figs. 11 a-c, 12 a-c.

?Ellisonia festiva (Bender & Stoppel), U element of Croft,

1972, p. 15-17, PI. 1, Figs. 15 & 16? PI. 2, Fig. 8.

Description: Bilaterally symmetrical bibbardelliform elements consisting of two equidimensional anterolateral processes and long, but generally broken, posterior process that may lit within the plane of bilateral symmetry or be slightly twisted out of this plane. Stout, peg-like, slightly reclined, medial cusp, generally subcircular in cross-section, commonly ornamented with sharp anterolateral costae. Angle of junction between anterolateral processes on anterior side of cusp approximately 110°. Anterolateral 115 processes slightly convex in proximal portion, curved downward and posteriorly in distal portion. Up to 6 dis­ crete, peg-like to slightly compressed, small denticles of equal size born on each anterolateral process, similar den- ticulation on preserved portion of posterior process.

White matter generally lacking, but may be present up to three-fourths of denticle height. Well-developed, narrow basal groove in all processes, shallow basal pit beneath cusp.

Remarks: Several bilaterally symmetrical form genera and species likely to belong in the multielement genus

Ellisonia have been reported from Leonardian & Guadalupian age Permian rocks. As previously discussed in conjection with the N element of E. n. sp., it seems likely that at least some of these are gradational variations in mor­ phology within the same species (see synonomy); but others may be distinct and consistent enough to indicate sub­ specific or specific variation. For example, Butler (1972) has described a bilaterally symmetrical element (Roundya sp. A, PI. 12, Fig. 11) with an angle of junction between anterolateral processes of 30 degrees, a significant dif­ ference from angles in excess of 100 degrees such as are present in A. forms included by the author in Ellisonia 116 n. sp. Butler also describes an unusual A3 element

(Roundya sp. B) which appears similar to the unassigned

Aj element of this report.

A few slightly asymmetrical A^ elements were observed

(PI. 3, Fig. 17). These asymmetrical elements may repre­ sent dimorphism or a response to environmental changes.

They are very uncommon, thus it seems unlikely that they represent a distinctive morphologic element type within the Ellisonia apparatus.

Material: 108 specimens from the Upper Plympton and

Gerster Formations in the study area and at Montello,

Ne v a d a .

Occurrence: Upper Plympton and Gerster Formations, eastern Nevada and west central Utah; Concha and Rainvalley

Formations, Arizona (Butler, 1972); ? Pinery Member of Bell

Canyon Formation, West Texas (Croft, 1972); ? Mid-Permian of Sicily and Zechstein Limestone of Germany (Bender &

Stoppel, 1965); ? Upper Permian of Poland (Szaniawski,

1969).

Repository: Figured hypotypes: O.S.U. 31324 (PI. 1,

Fig. 17; Pi. 3, Fig, 5); 31327 (Pi. 1, Fig. 20; Pi. 3,

Fig. 7); 31334 (Pi. 3, Figs. 6 & 10); 31337 (PI. 3,

Fig. 17). Genus NEOGONDOLELLA Bender and Stoppel, 1965

Type Species: Gondolella mombergensis Tatge, 1956

Diagnosis: A group of apparently unimembrate conodont species characterized by paired, individually asymmetrical, platform elements. These elements possess a nodose or denticulate, slightly to moderately arched median carina, a terminal or subterminal posterior cusp and a short anter­ ior process that may extend distally beyond the lateral platforms and bears the highest denticles. Finely to coarsely pitted platform-like lateral extensions are devel­ oped in most growth stages; the platforms are commonly joined posteriorly by a brim that encloses the posterior end of the carina. The basal side of elements displays a posteriorly expanded, longitudinally grooved keel that encloses a pit beneath the cusp.

Distribution: Species of Neoqondolella are known from upper Wolfcampian through Middle Triassic strata in western

North America. They have been recovered from Upper Permian strata in the Mediterranean, and from Upper Permian and

Lower Triassic units in Transcaucasia, southern Asia and

Greenland. To date, they are unknown from Permian and Lower 117 118

Triassic rocks in Europe, but have been recovered from the

Middle Triassic there.

Neogondolella n . sp.

PI. 2, Pigs. 1-9, 11, 14

Gondolella rosenkrantzi Bender & Stoppel of Clark and Behn-

ken, 1971, p. 429 & 434, PI. 2, Figs. 10-12, 14-17,

19, 20, 22.

Neogondolella rosenkrantzi (Bender & Stoppel) of Behnken,

1972, p. 133, PI. 2, Figs. 7 & 8; 1975, p. 307, Pi. 2,

Figs. 9-11.

?Gondolella rosenkrantzi Bender & Stoppel, 1965, PI. 14,

Figs. 4-6 (not Pi. 14, Figs. 7-11; Pi. 16, Figs. 17,

19, 20).

Diagnosis: unimembrate, elements platform-bearing, gondolelliform

Description; Slightly to moderately arched, individ­ ually asymmetrical, gondolelliform elements consisting of a denticulate to nodose median carina with we11-developed lateral platforms. Subterminal posterior cusp is generally enclosed by a poorly- to we11-developed brim. Anterior process extends slightly beyond anterior extremity of the lateral platforms. Upper surface of platform finely pitted. 119

White matter generally lacking, but may occur in cusp or

anterior denticles. Attachment surface includes keel con­

taining narrow basal groove, which expands into loop beneath

cusp.

Three growth stages of Neogondolella n. sp." have been

described by Clark and Behnken (1971, p. 434). These stages

are readily separated in the author’s material as well.

Small - Entire unit small, slightly to moderately arched. Carina bears 7 to 11 reclined denticles which are distinct and less nodose in appearance than intermediate

large forms. Posterior cusp commonly as tall as distalmost anterior denticle, rarely enclosed by very narrow brim-like extension of lateral platforms. Platforms narrow, slightly upturned, widest in midportion of unit and tapering moder­ ately posteriorly and strongly anteriorly. Anterior process may extend slightly beyond platforms. Distalmost 2 to 3 denticles of anterior process increase in height over other denticles, fused for about two-thirds of height. Basal

surface bears narrow keel with elevated lip which contains a slit-like basal groove. Basal groove runs entire length of keep and terminates posteriorly in strong, downwardly produced loop. Intermediate - Unit larger, moderately arched with

carina bearing 11 to 13 reclined, nodose denticles. Cusp

higher than other platform denticles, but not as high as

denticles on anterior process. Platform broader, moderately

upturned, no longer tapered toward posterior end of unit;

commonly joined posteriorly to form brim beyond cusp. Plat­

forms taper sharply about one-third the distance from ante­

rior end of unit, continue as very narrow rib on basally

deflected anterior blade almost to end of unit. Longitu­

dinal grooves in platform adjacent to carina. Distalmost

3 denticles increase markedly in height, fused for two-thirds

of height. Basal surface bears slightly raised keel.

Attachment surface within keel expanded to almost one-third

the width of the unit, contains narrow basal groove which

terminates in slightly elevated loop beneath cusp.

Large - Unit large, thick, slightly to moderately

arched with 14 or more denticles and nodes on carina. Cusp

barely elevated above surface of platform. Denticles

within platform generally overgrown and fused to form nodose

ridge. Nodes or ridges may develop posterolaterally to

carina on surface of platform. Deep longitudinal grooves

adjacent to carina and to posterolateral nodes. Platforms broad, thick, upturned; extend beyond cusp as distinct brim 121 which may develop posterolateral "ears" as it encloses

secondary nodes. Anterior process much like intermediate

forms. Keel barely elevated above basal surface; enclosed

attachment surface over one-third the width of the unit#

contains narrow basal groove which terminates in slightly

elevated loop. Loop and posterior portion of keel follow

subrounded to square outline of posterior end of platform.

Remarks: Specimens of Neogondolella from the Gerster

Formation were assigned to N. rosenkrantzi (Bender &

Stoppel) by Clark & Behnken (1971)# Behnken (1972, 1975a).

Comparison of Gerster material with topotypes of Bender and

Stoppel's N. rosenkrantzi from East Greenland led the author to conclude that the Gerster Neogondole1la repre­ sents a different species (E. Marcantel# 1973, p. 334) .

Similar conclusions have been reached by Behnken (1974# per. com.) based on material supplied him by Mr. Svend Stouge of Copenhagen# Denmark.

Neogondolella n. sp. is distinguished from N. rosen­ krantz i by the abrupt tapering of its platform one-third the distance from the anterior end# by its fused anterior denticles# by its more prominently elevated loop and less sharply ridged keel, by smaller# fused denticles or nodes on the carina in later growth stages# and by a broader. 122 more upturned platform and better developed groove adja­ cent to the carina. N. rosenkrantzi has a narrower plat­ form, which tapers gradually and continuously from pos­ terior to anterior end. N. n. sp. may be an evolutionary predecessor, descendant, or geographical subspecies of N. rosenkrantzi, as they display gross similarities in den- ticulation, development of basal structures and even the presence of auxiliary posterolateral ridges or denticles in large forms.

Neogondolella n. sp. is distinguished from N. serrata

(Clark & Ethington) by its abruptly tapered platform that lacks serrations. It is distinguished from N. idahoensis

(Youngquist, Hawley & Miller) of the Phosphoria Formation by its abruptly tapered platforms, long anterior blade and well-developed lateral grooves.

Material: 811 specimens from the Gerster Formation in the study area and Plympton equivalent rocks and the

Gerster Formation at Montello, Nevada.

Occurrence: Gerster Formation in eastern Nevada and western Utah, and Plympton equivalent rocks and the Gerster

Formation at Montello, Nevada; ? Mid-Permian of Sicily

(Bender & Stoppel, 1965) . Genus NEOSPATHODUS Mosher, 1968

Type Species: Spathognathodus cristigalli Huckriede,

1958.

Diagnosis: A group of single element conodont species

characterized by blade-shaped elements with a we11-developed

anterior process and a posterior process that is short to

absent. Commonly, species of Neospathodus possess a mid­

lateral rib that may develop into a platform in later growth

stages. The basal surface includes a basal pit partially

enclosed by a loop-like ridge and a laterally flaring basal

cavity sheath.

Remarks: It is possible that the elements herein assigned to NeospathoduS belong in a separate genus. These

elements display a posterior process, an uncommon feature

of other species of Neospathodus. In addition, they lack

a midlateral rib and a loop-like ridge enclosing the basal

pit. Pending further investigation of their affinities, however, the author has decided to follow the precedent of

Sweet (1970b), Clark and Behnken (1971) and Behnken (1972,

1975a) and include these elements in Neospathodus.

123 124

Range: As presently defined, the genus Neospathodus ranges from the Guadalupian or possibly Upper Leonardian into the Upper Triassic. Elements of Neospathodus have been recovered in western North America, southern Asia, Germany, and Sicily.

Neospathodus arcucristatus Clark & Behnken, 1971

Pi, 1, Figs. 14 & 19; Pi. 2, Figs. 10, 12, 13

Neospathodus arcucristatus Clark & Behnken, 1971, p. 436,

PI. 2, Figs. 1, 2, 5; of Behnken, 1972, p. 145, PI. 2,

Fig. 5; 1975a, p. 309, PI. 2, Fig. 8; of Butler, 1972,

p. 99, Pi. 12, Fig. 9; PI. 15, Figs. 1-5

Neospathodus cf N. divergens (Bender & Stoppel) of Butler,

1972, p. 100-101, PI. 15, Fig. 6.

?Spathocrnathodus galeatus Bender & Stoppel, 1965,

p. 351-352, PI. 16, Figs. 4 & 16.

Diagnosis: single element blade

Description: Strongly arched, asymmetrical, paired blades with laterally flaring, prominent basal cavity. Den­ ticles reclined, laterally compressed, inclined inward and sharply pointed. One large, discrete cusp developed at apex of basal cavity. Anterior denticle proximal to cusp 125

often equals cusp in size. Denticle size decreases dis-

tally. Distal denticles frequently fused. White matter

prominently developed in upper two-thirds to three-fourths

of all denticles. Anterior and posterior processes curved

slightly inward. Anterior process bearing 5 or more den­

ticles, posterior process 2 or more. Basal cavity lat­

erally expanded, subtriangular in outline with apex of

triangle directed anteriorly. Basal cavity extended as

narrow groove for almost entire length of both processes.

Remarks: In 1971, Clark and Behnken described a new

conodont species from the Gerster Formation, which they

assigned to Neospathodus and named N . arcucristatus. The author (E. Marcantel, 1973) regarded N. arcucristatus as

an occupant of the P position in Ellisonia n. sp. because:

(1) it is always associated with other Ellisonia n. sp. elements; (2) although it does not occur in all samples

containing other Ellisonia n. sp. elements, it is always

identified from abundantly productive samples in which

several element types of Ellisonia n. sp. may be distin­ guished; (3) it possesses denticulation and white matter

distribution similar to that of other Ellisonia n. sp.

elements. Subsequently the author has studied available

Upper Permian and Lower Triassic collections containing 126 other species of Ellisonia and observed no Ellisonia-type element bearing morphologic similarities to N. arcucrista­ tus . although morphologic counterparts of the other five elements of E. n. sp. were clearly present in these other

Ellisonia species. It is therefore concluded that N. arcucristatus is probably not an element in the apparatus of Ellisonia n. sp. and that the valid sixth Ellisonia n. sp. element has simply not been identified due to paucity and poor preservation of conodonts.

Because of their rapid evolution, Neospathodus arcucristatus and N. divergens are useful for zonation in the Gerster Formation. Broken specimens are, however, difficult to identify. N. arcucristatus appears to have two "cusps" above the basal cavity (Clark & Behnken, 1971).

These two prominent denticles have been used by Clark &

Behnken (1971), Butler (1972) and Behnken (1972, 1975a) as the most important distinguishing feature of N. arcucris­ tatus . If unbroken, however, N. divergens may also appear to have two "cusps" (see Pi. 1, Fig. 15 and Bender &

Stoppel, 1965, PI. 16, Figs. 1, 2b, 2c), hence this is not a reliable distinguishing feature. More consistent characteristics for separating N. arcucristatus from N. divergens appear to be: (1) overall number of denticles 127

(N. arcucristatus may have 12 or more, N. divergens gen­

erally 5 or 6); (2) number of denticles on anterior pro­

cess (N. arcucristatus 5 or more, N. divergens usually

only 4); (3) shape and denticulation of posterior process

(N. arcucristatus possesses a distinct posterior process bearing more than 2 denticles and including a narrow basal groove projected beyond flared basal cavity (Pi. 2,

Figs. 10, 12, 13); N. divergens bears at most 2 posterior denticles, which develop on the flared posterior portion of the basal cavity, no posterior process as such is developed (Pi. 2, Figs. 15 & 16).

Bender & Stoppel (1965) described and illustrated

Spathognathodus galeatus from Middle Permian rocks of

Sicily. Their description and illustrations suggest that

Neospathodus arcucristatus may be conspecific with galeatus. If this is the case, it would be necessary to assign elements of Neospathodus arcucristatus to Neo­ spathodus galeatus (Bender & Stoppel). The author re­ frains from making a final judgment on this possibility without further study of Bender and Stoppel's material.

Material: 192 specimens from the Upper Plympton and

Gerster Formations in the study area and from the Gerster

Formation at Montello. 128

Occurrence: Upper Plympton and Gerster Formations

in the study area and the Gerster Formation at Montello,

Nevada; ? Mid-Permian of Sicily (Bender & Stoppel, 1965).

Repository: Figured hypotype: O.S.U. 31322 (PI. 1,

Fig. 14; PI. 2, Fig. 12); 31326 (PI. 1, Fig. 19); 31331

(PI. 2, Fig. 13); 31332 (Pi. 2, Fig. 10).

Neospathodus divergens Bender & Stoppel, 1965

PI. 1, Fig. 15; PI. 2, Fig3. 15 & 16

Spathognathodus divergens Bender & Stoppel, 1965,

p. 350-351, PI. 16, Figs. 1-3.

Neospathodus divergens (Bender & Stoppel) of Clark &

Behnken, 1971, p. 436-437, PI. 2, Fig. 6

Diagnosis: single element species, blade

Description: Strongly arched, individually asym­

metrical, paired blades with laterally flared, prominent

basal cavity. Denticles discrete to slightly fused, re­

clined, laterally inclined, compressed and sharply pointed.

Apex of basal cavity surmounted by one large cusp, but

associated proximal anterior denticles may be nearly as

long as cusp. Denticle size decreases distally. White matter present in upper two-thirds to three-fourths of all denticles. Anterior process bears up to 4 denticles, the 129 distalmost being small and poorly developed. Distal end

of anterior process projects anteriorly beyond last den­ ticle. Distal portion of anterior process deflected down­ ward and slightly curved laterally. Posterior process

essentially nonexistent, 1 or 2 posterior denticles devel­

oped on flared posterior portion of basal cavity. Basal

cavity subtriangular in outline with apex anteriorly di­

rected, basal groove extends about two-thirds the length of anterior process.

Material: 10 specimens from the Upper Gerster For­ mation

Occurrence: Upper Gerster Formation at Montello, the Medicine Range, the Cherry Creek Range, the Butte

Mountains and Palamino Ridge (Phalen Butte); Zechstein

Limestone of Germany (Bender & Stoppel, 1965).

Repository: Figured hypotypes: O.S.U. 31339 (PI. 1,

Fig. 15; PI. 2, Fig. 15); 31340 (PI. 2, Fig. 16) Genus XANIOGNATHUS Sweet, 1970b

Type Species: Xanioqnathus curvatus Sweet, 1970b

Diagnosis: A group of conodont species characterized by f ive or six morphologically intergradational ramiform elements, and an ozarkodiniform element of the type placed in the form genus Xanioqnathus (Sweet, per. com). Distinc­ tive ramiform elements include a hibbardelliform A^ element that lacks small denticles anterior to the cusp, two types of hindeodelliform A^ elements (one displaying a bifid anterior process and one lacking a bifid anterior process), a distinctive P element of the type placed in the form genus Enantiognathus and an N element of the type placed in the form genus Cypridodella. Denticles are equal to slightly unequal in size, discrete, compressed, sharply pointed. White matter is often distributed in irregular

"clouds", giving the elements a "spotted" appearance

(Sweet, 1970b, p. 229).

Remarks: Sweet (1973a) suggested use of the name

Cypridodella for multielement conodont groups (typified by

E. qradata Sweet, 1970a) that include a cypridodelliform element in their apparatus. Subsequent investigations 130 131

(Sweet, per. com.) indicate that this group may be further

subdivided, on the basis of distinctions in elements in

the A^ position, into at least two genera, Xanioqnathus

and Cypridodella. Xaniognathus includes species in which

the A^ position is filled by hibbardelliform elements that

develop no denticles anterior to the cusp. The known range

of Xanioqnathus is Leonardian into Lower Triassic. Cypri­

dodella includes species in which the A^ position is filled

by hibbardelliform elements with small denticles anterior

to the cusp. Cypridodella ranges from upper Lower Triassic

to Upper Triassic (Sweet, per. com.).

Sweet has described five ramiform apparatuses of the

Xanioqnathus type from the uppermost Permian and Lower Tri­

assic of the Salt Range (Ellisonia gradata, E_. delicatula,

E. clarki, E. robusta and E. tort a, Sweet, 1970b).

Both Croft (1972) and Behnken (1972, 1975a) have described

a Xan iognathus type species they call E. tribulosus (trib- ulosa) from the Leonardian and Guadalupian of West Texas.

In addition, Butler (1972) has figured a specimen of the

form genus Cypridodella (cypridodella sp. A, p. 82, PI. 5,

Fig. 17), which may indicate the presence of a multi­

element species of Xan iognathus in the Wolfcamp (Lower

Permian) of southeast Arizona. 132

None of the above-mentioned multielement species was originally described as including a xaniognathiform

element, but all occur with one or more species of Xanioq­

nathus . In view of increased knowledge of Permian and

Triassic conodont faunas, these xaniognathiform elements

probably should be included in the Xaniognathus apparatus

(Sweet, per. com.). The various species of Xanioqnathus may be distinguished on the basis of changes in the O and possibly and N positions.

The Guadalupian species Xaniognathus tribulosus

(Clark & Ethington) of Behnken is clearly the same as the

species described as ID. tribulosus (Clark & Ethington) by

Croft. Croft's material was derived from the Pinery Mem­ ber of the Bell Canyon Formation as was some of Behnken's material. Included in Xanioqnathus tribulosus would be

the xaniognathiform element identified as X* abstractus

(Clark & Ethington) by Croft and as X» tortilis (Tatge) by

Behnken.

Baird (1975) has described a multielement species of

Xanioqnathus, Xan iognathus abstractus (Clark & Ethington),

from the Leonardian age Kaibab Formation. Behnken (1972,

1975a) records the presence of the form species Xanioq­

nathus abstractus from the Leonardian Bone Spring Limestone 133

and Victorio Peak Formation, suggesting the occurrence

in West Texas of a multielement Xan iognathus species like

that described by Baird (1975).

Xaniognathus tribulosus (Clark & Ethington) , 1962

PI. 1, Figs. 6 & 7, 9-13; Pi. 3, Figs. 3, 4, 9, 13

Ellisonia tribulosa (Clark & Ethington) of Behnken, 1972,

p. 125-130, PI. 2, Figs. 1-4; 1975a, p. 303-306,

PI. 2, Figs. 1-4, 6; of Croft, 1972, p. 17-19, Pi. 2,

Figs. 13-20; PI. 3, Figs. 1 & 2.

Diagnosis: six or seven member apparatus; P element,

enantiognathiform; 0 element, ozarkodiniform; N element,

cypridodelliform; A^ element, hindeodelliform with and without bifid anterior process; element, lonchodiniform;

A^ element, hibbardelliform.

P element

PI. 1, Figs. 10 & 11; PI. 3, Fig. 3

Apatognathus tribulosus Clark & Ethington, 1962, p. 107,

PI. 1, Figs. 3, 7, 13, 17.

Ellisonia tribulosa, LC element of Behnken, 1972, p. 126,

PI. 2, Fig. 1; 1975a, p. 304, PI. 2, Figs. 4 & 6;

of Croft, 1972, p. 17-18, PI. 2, Figs. 13 & 14. 134

Description: Individually asymmetrical, paired,

enantiognathiform elements with anterolateral processes of

unequal length produced from sharp costae on subcentrally

developed cusp. Cusp at least twice the height of other

denticles, inclined to slightly proclined, laterally com­

pressed, subtriangular in outline. Anterolateral processes

curved posteriorly to produce V shape when viewed from top

or bottom. Longer anterolateral process bears 4 or 5 dis­

crete, laterally compressed, slightly inclined, sharply

pointed denticles which decrease somewhat in height dis- tally. Shorter process bears up to 3 denticles similar to, but smaller than, those of longer process. White matter generally lacking. Small basal pit beneath cusp; narrow basal grooves present for one-half the length of each process.

Remarks: These elements are well-preserved and, with the 0 elements, are the most readily recognized in

collections at hand. They are not strikingly different

from the P (LC) elements of Xanioqnathus curvatus, X. elongatus and X. deflectens, but are probably separable on the basis of a more extended long anterolateral process and more abundant white matter in the Triassic Xanioq­ nathus species. 135 Material: 40 elements from the Gerster Formation

Occurrence: Middle portion of Gerster Formation, eastern Nevada; Bone Spring Limestone through Radar Lime­ stone Member of Bell Canyon Formation in West Texas and

Meade Peak Member of Phosphoria Formation, Idaho (Behnken,

1972, 1975a; Croft, 1972).

Depository: Figured hypotype: O.S.U. 31354 (Pi. 1,

Fig. 10); 31355 (Pi. 1, Fig. 11; Pi. 3, Fig. 3).

O element

PI. 1, Figs. 9 & 13

Subbryantodus abstractus Clark & Ethington, 1962,

p. 122-113, PI. 1, Fig. 20 [j?Pl. 1, Figs. 16, 21;

Pl . 2, Fig. 2 = Xanioqnathus abstractus (Clark &

Ethington) of Behnken, 1975^.

Ozarkodina tortilis Tatge of Clark & Behnken, 1971, PI. 2,

Fig. 18.

Xan iognathus tortilis (Tatge) of Behnken, 1972,

p. 162-163, PI. 2, Fig. 6; 1975a, p. 313, Pl. 2,

Fig. 13; ? of Butler, 1972, p. 118, Pl. 15, Fig. 15

(not Pl. 14, Fig. 5).

Xanioqnathus abstractus (Clark & Ethington) of Croft,

1972, p. 26-27, Pl. 1, Figs. 11-13. 136 ?Ozarkodina tortilis Tatge of Bender & Stoppel, 1965,

p. 348-349, Pl. 15, Figs. 16a, b & 17.

Description: Strongly arched, paired, individually

asymmetrical ozarkodiniform elements with markedly unequal

anterior and posterior processes. Posteriorly located

cusp prominent, slightly reclined, laterally compressed,

sharply pointed, subelliptical in cross-section, may bear anterior and posterior costae. In large specimens, den­ ticles immediately flanking cusp may be partially over­ grown. Anterior process 3 times length of posterior pro­ cess, deflected downward, longitudinally ribbed at mid­ height, bears 6 to 9 laterally compressed, moderately re­ clined, sharply pointed denticles of equal size. Denticles may be discrete or fused for one-half to three—fourths of height. Posterior process short, deflected laterally, bears up to 4 slightly inclined denticles similar to, but smaller than, those of the anterior process. White matter rarely developed, may occur as irregularly distributed spots. Attachment surface slightly flared beneath cusp with sharply pointed basal pit, extended as very narrow basal groove for approximately three-fourths of the length of both processes. 137

Remarks: Behnken (1975a, p. 313) has distinguished two species of Permian xaniognathodontiform elements.

Xanioqnathus abstractus (Clark & Ethington) and X. tortilis

(Tatge). These are probably the 0 elements of two multi­ element Xanioqnathus species. Behnken distinguishes X- abstractus from X. tortilis on the basis of a more robust blade and fewer denticles on both processes in X. abstrac­ tus.

The 0 element of Xaniognathus tribulosus is readily distinguished from the Triassic xaniognathodontiform ele­ ments X* curvatus, X. deflectens and X. elonqatus by its longer and more robust processes, the greater number of denticles on both processes and overall larger size.

Material: 48 specimens from the Gerster Formation in the study area.

Occurrence: Middle part of the Gerster Formation, eastern Nevada and west central Utah; Cherry Canyon and

Bell Canyon Formations, West Texas (Behnken, 1972, 1975a;

Croft, 1972); Concha and Rainvalley Formations, Arizona

(Butler, 1972); Meade Peak member of Fhosphoria Formation

(Clark & Ethington, 1962); ? Mid-Permian of Sicily (Bender

& Stoppel, 1965). 138 Repository: Figured hypotypes: O.S.U. 31353

(PI. 1, Fig. 9); 31357 (Pi. 1, Fig. 13).

N element

PI. 3, Fig. 9

Ellisonia tribulosa, LA^ element of Behnken, 1972, p. 126,

PI. 2, Fig. 4; 1975a, p. 304, Pi. 2, Fig. 3? of

Croft, 1972, p. 18, Pi. 2, Fig. 15.

Description; Paired, individually strongly asymmetri­ cal, cypridodelliform element with two markedly unequal processes developed from sharp costae on cusp. Cusp 2 to

3 times height of other denticles, laterally compressed, sharply pointed, slightly reclined, with flattened, pos­ teriorly twisted posterolateral lip. Posterolateral process longer, downwardly deflected, bears 2 to 4 laterally com­ pressed, sharply pointed denticles which increase in height toward cusp. Anterolateral process shorter, may be aden- ticulate or bear 1 or 2 small denticles similar to those of the posterolateral process. White matter occurs as irreg­ ular spots in denticles. Shallow basal pit present beneath cusp.

Remarks: The specimens in our collections are not well-preserved; but abundant, excellent material is 139 available in the collections of croft and is also clearly described by Behnken- The N element is superficially simi­

lar in appearance to the A^ element, but is more asymmetri­ cal, with the processes twisted nearly into an anterior- posterior position. The lip on the cusp is distinctly flat­ tened and twisted posteriorly, and is developed on the pos­ terolateral portion of the cusp rather than in a posterior position as in the A^ element. N elements of Xanioqnathus tribulosus are separated from N elements of Ellisonia n. sp. by their strong asymmetry, flattened lip and generally aden- ticulate anterolateral process. They are separated from N elements of Anchiqnathodus n. sp. by their shorter postero­ lateral process, denticles of equal size, and lack of evenly distributed white matter.

Material: 7 specimens from the middle part of the

Gerster Formation at the Medicine Range, Cherry Creek and

Currie Ravine Sections.

Occurrence: Middle portion of the Gerster Formation,

Nevada; cherry Canyon and Bell Canyon Formations, West Texas

(Behnken, 1972, 1975a; Croft, 1972), Meade Peak Member of the Phosphoria Formation, Idaho (Clark & Ethington, 1962).

Repository: Figured hypotype: O.S.U. 31358 (Pi. 3,

Fig. 9). 140 element

Pi. 1, Fig. 7

Ellisonia tribulosa (Clark & Ethington), LB^ and LB^ ele­

ments of Croft, 1972, p. 18, Pi. 2, Figs. 18-20j ? of

Behnken, 1972, p. 127 (not figured).

?Hindeodella sp. b Bender & Stoppel, 1965, p. 345, PI. 15,

Fig. 7

Description: Moderately to strongly arched, paired,

individually asymmetrical, hindeodelliform elements with

short posterior and longer anterior processes. Denticles

discrete to slightly fused, laterally compressed, sharply

pointed, generally decrease gradually in size away from

cusp. Cusp may be similar in height to proximal denticles or significantly taller. Posterior process short,

straight, bears 1 or 2 denticles. Anterior process long, downwardly deflected with 6 to 8 denticles. In some ele­ ments, anterior process becomes bifid proximal to the cusp and each segment of the bifid process bears 2 or more den­ ticles. White matter rare, occurs as spots in denticles.

Attachment surface developed as basal pit beneath cusp, extends as distally narrowing groove beneath processes.

Remarks: The A^ position of Xanioqnathus tribulosus

is occupied by two element types, one possessing (A^a) and 141 one lacking (A^b) a bifid anterior process. If these two elements are assigned separate positions within the X. tribulosus apparatus, then this species must be considered to have a seven rather than six member apparatus. Some

Triassic ramiform species probably related to Xaniognathus appear to lack elements with bifid anterior processes

(Sweet’s 1970b Ellisonia torta, IS. delictula and E. clarki) , thus the characteristic would seem to be solely a specific one and might best be considered a subdivision, perhaps dimorphic, of the A^ position rather than an indication of a distinctive new position within the apparatus.

The A^b element of xanioqnathus tribulosus is dis­ tinguished from the A^ elements of Ellisonia n. sp. and

Anchignathodus n. sp. by its very short posterior and long anterior processes and its gracefully curved, compressed denticles of nearly equal size.

Material: 15 specimens from the middle part of the

Gerster Formation.

Occurrence: Middle portion of Gerster Formation;

Cherry Canyon and Bell Canyon Formations, West Texas

(Behnken, 1972, 1975a; Croft, 1972), ? Mid-Permian of

Sicily (Bender & Stoppel, 1965). 142

Repository: Figured hypotype: O.S.U. 31352 (PI. 1,

Fig. 7).

A^ element

PI. 1, Fig. 12; PI. 3, Fig. 13

Lonchodina muelleri Tatge of Clark and Ethington, 1962,

p. 110-111, PI. 1, Fig. 4; ? of Bender & Stoppel,

1965, PI. 15, Figs. 13 & 14 (not PI. 15, Figs. 12a &

b) .

Ellisonia tribulosa, IA^ element of Behnken, 1972,

p. 125-126, PI. 2, Fig. 3; 1975a, p. 304, PI. 2,

Fig. 2; of Croft, 1972, p. 18, PI. 2, Figs. 16 & 17.

Description: Paired, individually slightly asym­ metrical, lonchodiniform elements with subequal antero­

lateral processes produced from costae on the centrally

developed cusp. Prominent cusp 2 to 3 times height of

other denticles, laterally compressed, sharply pointed,

subtriangular in cross-section, with laterally skewed posterior lip produced from sharp posterior costa. Both

anterolateral processes denticulate, projected laterally

and curved downward, bearing 2 to 3 discrete, laterally

compressed, slightly reclined denticles. White matter may occur as irregular spots in denticles. Expanded basal pit 143

present beneath cusp and posterior lip# produced as dis- tally narrowing basal groove beneath processes.

Remarks: The A^ element of Xanioqnathus tribulosus may be confused with the N element of the same apparatus

(see discussion under Xaniognathus tribulosus, N element) or with the N element of Ellisonia n. sp. It is distin­ guished from the Ellisonia N element by its flattened, compressed appearance, smaller size and less prominent posterior lip.

Material: 3 specimens from the middle part of the

Gerster Formation at the Currie Ravine and Cherry Creek sections.

Occurrence: Middle part of Gerster Formation;

Cherry Canyon and Bell Canyon Formations, West Texas

(Behnken, 1972, 1975a; Croft, 1972); ? Mid-Permian of

Sicily (Bender & Stoppel, 1965).

Repository: Figured hypotype: O.S.U. 31356 (PI. 1,

Fig. 12; PI. 3, Fig. 13).

A^ element

PI. 1, Fig. 6; Pi. 3, Fig. 4

Ellisonia tribulosa (Clark & Ethington), U element of

Behnken, 1972, p. 125-130, PI. 2, Fig. 2; 1975a, 144

p. 303, PI. 2, Fig. 1; of Croft, 1972, p. 17-19,

PI. 3, Figs. 1 & 2).

Description; Symmetrical hibbarde11iform element with two gracefully downswept anterolateral processes and a slightly arched posterior process. Central cusp pointed, reclined, laterally compressed, ornamented by anterolateral and posterior costae from which processes are produced.

Anterolateral processes bear at least 4 slender, reclined, pointed denticles. Posterior process bears at least three denticles similar to those of anterolateral processes.

White matter distribution irregular. Basal cavity a small pit beneath cusp, projected as narrow basal groove for about three-fourths of process length in all processes.

Remarks; Only one broken specimen of the A^ element was recovered from our collections. This element clearly lacks development of small denticles anterior to the cusp, thus separating Xanioqnathus tribulosus from related upper

Lower Triassic to Upper Triassic species assigned to Cyp- ridodella (Sweet, per. com.). It is readily distinguished from the A^ element of Anchignathodus n. sp. that lacks a posterior process and from the A^ element of Ellisonia n. sp. that is larger and has peg-like denticles and less markedly curved processes. 145

Material: 1 specimen from the Gerster Formation in the Cherry Creek Mountains.

Occurrence: Gerster Formation at Cherry Creek

Section, eastern Nevada; Cherry Canyon and Bell Canyon

Formations, West Texas (Behnken, 1972, 1975a; Croft, 1972).

Repository; Figured hypotype: O.S.U. 31351 (PI. 1,

Fig. 6; PI. 3, Fig. 4) .

Unassigned Elements

Unassigned A^ ? element

PI. 3, Figs. 1 & 2

?Roundya sp. B Butler, 1972, p. 108-109, PI. 12,

Figs. 27-31.

Description: Slightly asymmetrical hibbardelliform element with two nonsymmetrical anterolateral processes and an asymmetrical posterior process. All processes robust, generally broken, bearing up to three peg-like, widely spaced denticles. Both anterolateral processes curved slightly downward, one process curved anteriorly, one posteriorly. Cusp slightly reclined, laterally in­ clined. White matter distribution irregular where observ­ able. Basal cavity a pit beneath cusp, extends as narrow groove beneath processes. 146

Remarks: Eight specimens of this strange looking element were recovered from the Gerster Formation in the study area and from Plympton equivalent rocks at Montello.

Two specimens are illustrated (Pi. 3, Figs. 1 & 2). Ori­ entation of these elements is a difficult process? the author is uncertain that they are, in fact, A^ elements, but can discover no other apparatus position for which they would be suited. They are definitely Ellisonia type ele­ ments. Most likely they are an asymmetric A^ element, either an aberrant form, a dimorph, or a variation pro­ duced by environmental changes. They appear similar to

Roundya sp. B described by Butler (1972) from the Concha

Formation in southeastern Arizona, perhaps Gerster speci­ mens are simply less completely preserved and hence more difficult to understand than Butler's material.

Material: 8 specimens from the Gerster Formation and from Plympton equivalent rocks at Montello.

Occurrence: Gerster Formation, eastern Nevada and western Utah, ? Concha Formation, southeastern Arizona

(Butler, 1972).

Repository: Figured hypotypes: O.S.U. 31359 (PI. 3,

Fig. 1); 31360 (Pi. 3, Fig. 2). CONCLUSIONS

The Gerster Formation of eastern Nevada and western

Utah was deposited on a broad marine shelf lying south and southeast of the Phosphoria Basin. Faunally and litholog- ically the Gerster Formation is markedly homogeneous over its regional extent. The basal 50 to 100 ft (15-30 m) of each section consists of sparry packstone, indicative of deposition in the higher energy, shallower, initial trans- gressive phases of the Gerster sea. Overlying units are micritic packstone and wackestone, deposited in a lower energy, probably deeper, marine environment. Sections measured at Currie Ravine, the southern Pequop Mountains, and Gold Hill are much thinner than others and consist pri­ marily of sparry packstone. They formed along an episo­ dically active, east-west trending high, where the water depth remained shallower for a longer period than on the rest of the Gerster shelf. The section in the Confusion

Range is thickest and contains few megafossils and no con- odonts in the upper 250 ft (75 m). This interval probably reflects shallow, restricted marine deposition during the 147 148

final phase of the Gerster sea and may have been erosionally

removed elsewhere. Limestone units containing brachiopods

and bryozoans in the uppermost Plympton Formation were

sampled at several localities. Lithologically they resem­

bled the Gerster Formation, but differences in the brachio-

pod and conodont fauna suggest they formed under somewhat

different, perhaps shallower, conditions.

Conodonts assigned to five genera and six species were recovered from the upper limestone units in the Plymp­

ton Formation and from the Gerster Formation. Their dis­

tribution roughly delineates four zones, which can be used

in correlating measured Gerster sections. When compared with conodonts recovered from the North American standard

Permian section in West Texas, the Upper Plympton and Ger­

ster faunas clearly demonstrate a Guadalupian age, but con­ tain no indicators restricted solely to Wordian or Capitan-

ian. Brachiopods from the Gerster Formation suggest a

Wordian age (Wardlaw, 1974a & b) and in conjunction with conodonts would seem to indicate a Wordian age for the

Gerster Formation.

Comparison with other known Permian conodont faunas

indicates a good correlation between the Gerster Formation

in the study area and the transitional Gerster/Phosphoria 149 deposits at Montello, Nevada. Correlation also exists be­ tween the Gerster Formation and some part of the Cherry

Canyon and Bell Canyon Formations in West Texas (Behnken,

1972, 1975a; Croft, 1972). Possible correlations exist with the mid-Permian exotic blocks of Sicily (Bender &

Stoppel, 1965), with the Zechstein Limestone of Germany

(Bender & Stoppel, 1965) and with the Upper Permian of

Poland (Szaniawski, 1969). APPENDIX A

Measured Sections

150 151

cherty cherty cherty interval limestone dolomite

Lithology Symbols Conodonts m = mudstone Anchiqnathodus n. sp

= wackestone Ellisonia n. sp.

9 = packstone Neogondole1la n. sp.

« = grainstone Xan iognathus tribulosus = sample unidentified ramiform elements

Neospathodus arcucr istatus

Neospathodus divergens

LEGEND FOR APPENDIX A, FIGURES 26-38 1 5 2

E i

*=— *

XI MI I $ > E2>

«XH

V*

tooH

/

S ttO -i

■ « p « » * » a ■ » « LITHOLOCV %wtf CMXKMT FlfMCNT /lO O M B wsriHtuTm DISSOLVED SAMPLE

APPENDIX A, FIGURE 2 6 - MEASURED SECTION AT THE BUTTE MOUNTAINS, NEVADA

SECS ET • M , T*f E M > M E «OE 153

e a n i i < i fOOOH

Z 3

ii ii i i I I

*L t * • > lit h o u w t CONODONT m Of SPECNtfNS ELf ME NT /lOOfitf&OF OT5TNIBOTKM DISSOLVED SAMP1C

APPENDIX A , FIGURE 2 7 - MEASURED SECTION AT THE CHERRY CREEK RANGE, NEVADA

SEC 4, T * P ITU, PV6E M E X A, FI ON AT THE CONFUSI UTAH A T U , E G N A R N IO S U F N O C E H T T A N IO T C E S D E R U S A E M - 8 2 E R U IG F , A IX D N E P P A SfKSm F O tmATM « 600- 200 - 0 0 H - J UTHOL06T % SILT * m %«MCMora» T * f 1 * 5 * M£ %« ivo » ms IT1UK WSSGlVt[) F DI5TM1VUTKM SAM* ,*0* MQ 5PfC>l*f(,0*000*1 N3 LMN /NDO ELEMENT 0 r M I M ms s

154 K N T 'i T > \

♦00 - 1

KXH /r7\ x ""I

J ■>

P-

I i -L-L-L I i i * i i i I t ► « 0 s 0 • » » «0 9C 0 » » C ft » JO 40 0 J * * * f t ft UThOLOW % SILT % NUCMOPOK %§3V0Z0APS %cftmoffis iOftOOCWT MO SPfClWCMS ElEMFIT fKwas OfiTfWcHON dissolved s a m p l e

APPENDIX A , FIGURE 29 - MEASURED SECTION AT CURRIE RAVINE, NEVADA SOUTHEAST 1/4 TIP, 30 R i ROE 64 E T 1 f

X N I I r> ► r

/ ; A A

i

fclJ 2 ,, i i . I ? ■ ■FI o i * ■ m p ) ■ » • ■ I «■*»»»

APPENDIX A, FIGURE 30 - MEASUREO SECTION AT GOLD HILL, UTAH MOOT 114*11 UMSITUOC, 40*K>’l L4TITU0C 2 7WD*

nrnFmtf f&WTM N - t&smt m m r m 200 l M 0 X A, GURE 3 - MEASURED SECTI N THE MEDI NE RANGE, A D A V E N , E G N A R E IN IC D E M E H T IN N IO T C E S D E R U S A E M - 31 E R U IG F , A IX D N E P P A - - j 1 J A 511T % aim ? >

I ■ N • It ■ * N Xsuottofoes W = C * , I I « E M i N n W T , * = ICCTWO U *C S,TF (*•£ *0€ £ • * ( * 7 TWF * , tS *£C 7UA %OTHQNB m t m ±~L- * Xcnmoos »e •

» I < I I i1 I orenwurw CONODCWr fLEICMT « i r «t to it i DISSOLVED SMIPLf MO MO SPfClHfW />oo om 157 4 ► Xi NI I

>r ] ZD

>trn U_1 bJ— I L_ L l r i ■ ■ i__ L_ • t » i C t ( ( c « K » *c so o « to s « *> «c 10 to k m h to i t jThOlMF % S1L1 % eRACHICfWS %MYOIO*M %C*IHO«S CONOOOOT NUMBER Of SPECIMENS /IOC M S ELEMENT distribution OF DISSOLVED SAMPLE

APPENDIX A, FIGURE 32 - MEASURED SECTION AT MONTELLO, NEVADA SECS IT a 18, TWP 39N, WE 68E 1 2

■ -1 I n 'A I I yy ♦0 0 - y

a >

100-I

> 7 > L J r?: . 1 . KIM a ( < * a * » it «t C 1C K X c 0 EBtAtt t ♦ I I >0 LlTHOLWir % 5HT % BMCHHOPCOS % M r a Z 0 M S % C A IW B S COW DON' W SPEC K tN E Ei£KENT x DiSfmftjTlON Di5SC«ED

APPENDIX A, FIGURE 33 - MEASURED SECTION AT PHALEN 9UTTE, NEVADA SOUTHEAST 1/4 TWP 29N , RGE 63E 159 PEDX , IUE 4 3 FIGURE A, APPENDIX TIJO UTOLOCT ■ M ■ ■ 0 « IB II AUE SCIN T H SUHR POO MOUNT NS, NEVADA , S IN TA N U O M PEOUOP SOUTHERN THE AT SECTION EASURED M ' 1 1 > «os %«f uw zu fQ « % s o *« w u « % u s H see t, Ttf Ttf see t, < wr3w r Z, 0 M iMI t - 30 « 0 m, INC. «€ ET^ s .j. .i. e a * w o i T - r - ^ r %CANHD9 COMOOOKT NC SPfCW£« NCSPfCW£« COMOOOKT %CANHD9 m m m m *e

10 tTUB HS1E U W HSS01VEDU DtSTWUTBH cWT O GMS /OO EcEWNT E 1 i : [ 0 , H i % ► H

APPENDIX B

Distribution of Conodont Elements

by Sample for each Measured Section

Note: Samples 72JH-0 through 72JH-626 from the Montello Section (Table 7) contain elements similar to Ellisonia n. sp. For convenience, these elements are recorded in the Ellisonia n. sp. category, but all elements so recorded actually represent the "unidentified ramiform elements" discussed in con­ junction with the Montello section in the text.

161 Anehianathodus n ■*P E l l i s o n i a n . s p . Neosoathodus Nj_ Keoaondolella n.*o. X a r iosr.at'nus tri's j l e SUS

S u a p lt A1 A2 A3 N 0 PF A1 A2 A3 N 0 t arcucristatus d iv * r q e n « w r A1 A2 A3 S 0 P F A3

7 3 J F -0 3 1 2 4 1

7 2 J 8 -1 5 0 2 1 2

175 2 1 5 1

200 11 9 3 6 2 74

315 17 1 3 6 3 100 5

253 1

300 6 1 1 2 1 13 3

335 3 1 2 1 24

350 3 3 1 22 4

365 1

195 4 1 2 4 1 70 5

42 0 11 4 2 4 7 42 4 445 1 1

47 0 1 1 1 1 2 23 2

4 SO 1

505 2 5 2

530 1

635 3 1 2 7

685 3

710 1 5 4 1 890 1 1 2 IS 2

940 _ _,

975 162

Table 1* Conodont element distribution by sample - Butte Mountains Anch icn«thod\j» n ■»P» B l l l a o n i i n . • p . Keosnathodus S«oqondolell« n.«o. X a n io o r athu* tribuleius 7

S a n p l* A1 A2 A3 K 0 P F A1 A2 A3 N 0 F •rcucristatua d lv e r v e n s w F A1 A2 A3 tf 0 F r AS

7 1 J F -0 3

10 3 4

70 1 4

30 2 1 2 1 5

40 2

47 1 2 9

355 3 1 1 2 2 42 5 ’

365 8

375 9 1 2 5 36 7

385 20 1 395 7

405 1 3

415 1 1 2 7

435 -_

433 1

445 1 2 1 1

455 2 1 1 8

465 1 9 1

475 1 3 5

485 16

495 1

305 - -

515 2

535

535 4

Table 2. Conodont element distribution by sample - Cherry Creek Range Anchlnnmthodos n .s p E l l i s o n i a n . Hcoscathodus E j. Xeooondolella n.ip. Xanloqnathus tr&uloius ?

S * n p l« A1 A2 A3 N 0 P F A1 A2 A3 N 0 F arcucrlst&tua diveroans V F A1 A2 A3 K 0 PF A3

71JF (c o n td )

545 1 5 1

555 - - - - -

5 6 * 3

575

585 1

595 2

605 1 1

615 4 1

673 3

634 2 2 6

646 5 2

655 5

665 1 1 4 2 1 1

675 3 4 3

684 17

698 4

708 5 3 2

718 ------_ -_ m 730 4 1 23 1 7 23 26 1 1

740 -----_ __

750 3 1

759 3 3 3 1 1 2 1 1

774 11 5 1 26 53 31 2 3 10 4 2 164 706 2 1 3 1

Table 2 - continued AneManatbodus n.ac * E l li s o n ia n . »P. Neosoathodus N. Neoqondolella n.ao. Xanioarathuf t r i b j l o s t s *

S a r p l* A1 A3 A3 S 0 P r A1 A2 A3 B 0 T ■rcueristatus divercens w 7 A1 A2 A3 N 0 PF

7 lJ r (c o n td )

817 4 2 1 2

860 2 4 1 7 19 12 1 1 2 4

870 6 14 6 2

aas -- -

900 - - -

930 1 2

930 1

9^0 1

950 1 4

960

970 3 3

980 - --

990

1003 ------_ - •*•

1015 5 6

1037 1 9 9 1 2 165

Table 2 - continued Anchionathodus n • *P . Ellisonia n. *p - NeosDathodui Nj_ Heooondolella n.SD. XaniotinetJiiia trlb'jlos-jg 1

S a r.p l* A1 A2 A3 H 0 PF A1 A2 A3 N0 F arcjcristatus d iv e ra a n g W F A1 A2 A3 H 0 P F k 2

71 JE -1 3 3 1 5 4 34 4 j 0 13 3

20 3 1

40 5 4 7 7 15 6

47 2 1 6 1

55 2 17 4

66 6

77 1 1 7 2

85 1 2 13

90 6

99 10 109 --- - ._ * __ * 120 2 5 1

123 2 1 145 3 3 1 a 2 25 5

155 1 l 1 20 165 6

175 7 190

191

200

207 l 14 2 210

220

2 )0 166 i

Table 3. Conodont element distribution by sample - Confusion Range Anehiemathodua n -»P E l li s o n ia n . ■P* Neospathftdus Nj_ Neoqondolelia n.ao. Xaniecnathua tribtileava T

S a n p l* A1 A2 A3 K 0 P F A1 A2 A3 N 0 F arcucristatus d iv e rq e n a w F A1 A2 A3 N 0 P F A3

71JS (e o n td )

240 . ------

249 2

254 - ' ------

261 ------271 ------

299 1 1

303 ------

310 1 3

320 8 1

330 1 1 2 4 340 1

350 6 3

361 1 1 30 2 15

369 1 380 ------390 ------

400 1

410 3 10

420 1 1 429 7 6

441 ------

459 8 5

462 ------w -

472 1 3 167

Table 3 - continued t

Anchianathodus n .*P E l li s o n ia n.■p. Seospathodus S i Neoao n

S *7 .p l« A1 A2 A3 S 0 P F A1 A2 A3 N 0 F areucriatatus d iv e ro e n a W F A l A2 A3 V 0 ? F n'l

71JE (c o n td )

469

490 - ---

500 - -••

513 -- • . m 530 1

539 1 543

553 - - - *

560 2 570 4

560 1

595 5 602

616 - -- *-

630 -- - *

630 2

64 0 m

655 - - - * m

660 - -- -

660 1 4

700 3 ■ 1 707

711 4 1

724 - - - 168

Table 3 - continued Anchierrathodu.i n .s p E l li s o n ia n . >P* Ncosrathodus Keocrondolella n .tc. Xanloonatbus t r i b u l o i - s •»

S a is p l* A1 A2 A3 8 0 P r A1 A2 A3 N 0 r arcvicristfttus d lv e rq e n s w P A1 A2 A3 K 0 P F k i

71JE (e o n td )

731

765 ------

776 - - - - * ------

785 - - - - * ------

790 l .. . . 8X8

B24 1 4 2 . 889

905 - - -

925 - - -

928 ---

945 - - -

956 - - -

975 - - -

990 - - -

1000 ------

1008 - --

1017 - - -

1038 ---

1065 - - -

1080 - --

1089 -- -

1100 169

Table 3 - continued Anchicnathodus n .*P E 1 1 is o n la n . 9 p . Neoapathodu* S i Neoaondolella n„»p. Xanioentthua tribuleaus 7 Sam ple A1 A2 A3 N 0 P r A l A2 A3 V 0 P arcucristatus d lv e rtre n a W r A l A2 A3 N 0 P F A3

73JC -96 2

110 1

114 3

71JC - 1 2 1 1 1 22 2

10 2 8 2

70 1 4

79 5 1 3 7 1 30 9

3B 1 1 24 2

50 2 1 6

60 1 1 2 18 1

70 m --

85 2 2 1 8 112 1

115 5

130 1

130 2 2 4 1

140 2

150 1 1 3

161 1 11 2

196 1 12

293 m ---

331 4 6

360 • 1

370 3 8 9 1 1 3 2

380 2 1 5 2

390 1 23 48 23 2 170

Table 4. conodont element distribution by sample - Currie Ravine Anchionathodus n ■ sp E l l i s on la n . s p . Keospathodus N_i_ Vcocondolella n.oD. Xaniccnathus t rib J le I us 7

S arrpla A l A2 A3 N 0 P t A l A2 A3 N 0 F arcucristatus dlverqena W F A l A! A3 N 0 F F a :

71JC (c o n td )

399 ------

410 1 1 3

421 5 4 1 33 40 18 3 6

444 1 27 37 34 1 3 1 5 2 3 2

4 5 ! 9 9 9 3

4 6 0 2 1 24 52 42 2 1 4 3

469 2 12 19 6 2 1 4 3 3 495 3 42 1 1 505 1

523 3

■ • 171

Table 4 - continued Anchlqnattodus n *sp E l l i s o n i a n . *P. Neosoathodus K. Neoqondolella n.io. Xar.ioonathus tr It -'1C t ‘: i ? * “ S t n p l* A l A2 A3 K 0 PF A l A2 A3 N 0 F sreucristatuad iv e r q e n s w F A l A2 A3 N 0 P r ft j

7 1 J I- 0 2 1 l

11 1 l 21

158 2

180 1 1 7 2

190 2 200

210 5 220

278 12

750 1 4 260

270 1 1 1 11 2

780 1 1 2 15 1

290 2 4 1 300 4

310 - - - -- 370

330 1 1 1 2 17

3*10 1

350

380 2

370 3 6

390 ------4G0 3 1 l 172 410 8 3 1

Table 5. Conodont element distribution by sample - Gold Hill Anehigntthodua n • *P E l l l s o n l l A t •P. Neoaoathodus N j. Feogondolella n.io. Xaniocnathua trlb-jloam ?

S a n p l* A l A2 A3 K 0 PF A l A2 A3 8 0 F arcueristatus d iv e rq e n a W F A l A2 A3 K 0 P F A3

73JD -0 ---

5 6 6

71JA -4 3 1 6

IS 13 4 1 6 6 31 9

29

35 1 1 1 3 4 27 3

45 10 5 5 4 84 7

55 5 2 3 6 31

65 4 1 1 10 1

75 1 2 5 39 2

85 1 1 ] 14 1

95 - -

105 1

115 - --

125 1 1

139 21 6 5 e 7 97 6

145 1 l 4 1

155 -- •

165 2 1 3 15 3

175 - - -

185 2 1 1 2 6 X

195 1 2 1 10

205 1 28

215 5

225 3 i 173

Table 6, Conodont element distribution by sample - Medicine Range Anchiassthodus n .«P E l l l s o n i a n . •P. Keosoathodus iL . Bepcondolall* n .s p . Xantoanathus trlbulosu# 7 S a r.p l* A l A2 A3 N 0 P F A l A2 A3 N 0 F arcueristatus d iv e r e e n * w F A l A2 A3 N 0 P r A3

71JA (c o n td )

235 2 1 1 17 5 2

246 3

265 -- -

295 1 2 5

305 3 1 14 1 12 23 1 2 312 1 3 5 10 325 2 1 4 2

334 6 1 1

344 2 1 2 18 10 2 1 1

352 --- 365

375 _ *

385 1 1 9 11 13

395 2 10 1 11 10 1

405 1 1 4 1 1

415 2 1

421 2 4 2

435 1 1 1 8

446 1 1 2 1 1 1

455 1 1 8

465 1 1 2 9 1

475 1

4 65 1

495 - - - - 174

Table 6 - continued Ar.cMenatViodus n • *P El l i s o n i a n . s p . Keospafhodus Kcoqondolclla n.ap, Xanlotrnathua trtb ’jloa';i T

S t n p l* A l A2 A3 K 0 P F A l A2 A3 N 0 F arcucriatatua div ercre na W F Al A2 A3 N 0 P F A3

71JA (c o n td )

505 1 1 2 17

515 4

S25 1

537 1 579

589 9 ’ 619 4 640

664 3

677 3

686 2

707 3

716 1 1 5 715 4 3 2 31 16 749 2 1 ? 1 764 1

794 - _

BO 7 1 810

- • 175

Table 6 - continued # AncMqnatbodus n.sp E l l i : On in n . ■ P. tJcosuathodus N. tfeoqondolella XAni&Tri&thi s t r i b u l c i " i

A l A2 A3 S 0 ? F A l A2 A3 K OF srcucristatus iiv e r c e n s W F A l A2 A3 S 0 p T A3

72JH -0 1 1

140 - - - - _

175 7 9 1 7 4 40 30 5 6 150 5 2

165 2 2

195 1

105 1

215 ------225 - - - - • m 235 2 1

245 1 2 3 32

255 1

366

376 1 1 2

* 395 ------_ .

405 3

465 -_

475 1

465 4

496 -• 506 3

520 1 3 1

526 _

556 23 '

570 14

580 2

S90 ------_ ------176 i--~ - . “ Table 7. Conodont element distribution by sample - Montello AncMon»thodu« n * ®P E l l l s o n i a A p■ p . Naosoathodus IL. CaMondolalla XeniwnetVjs tribulosus ?

S a ir p l* Al A2 A3 S 0 ? r A l A2 A3 N 0 r areucristatus d iv e r a e n i w F A l A2 A3 N O F F A3

72 JH te o r.td )

616

02 6 - --

635 5

645 i 4

655

665 - - -

€75 1 3 1

665 1 4

840

852 ---

861 1

870

8 * 0 - - ■ - 60S 1

903 3

928 4 1 3

940 1

950

960 2 1

971 2

LOIS 2

1025 1 4

1035 2 2 1 7 1045 5 177 Table 7 - continued Anchlanathodua n • *P * E l l i s o n i a n . ap. Neoapatbodua *L. Neocrondolella n.»o. Xanioanathus ttlb-jlosus ? S a n p li A l A2 A3 It 0 P r A l A2 A3 N 0 F arcueristatua d lveroana W F A l A2 A3 S 0 P F A3

77JH (c o n td )

1055 9 16 6 12 12 100 14 3

1065 3 1 3 12 9 50 S 3

1074 1 1 I 6

1100 4 1 1 4

1110 1

1120 2

1140 - - --

1160 2 1 7 1

1178 5

1416 - --

1550 - --

1563 -- -

1591 ---

1597 ---

1619 ---

1635 - - -

1636 .*_

1640

* 178

Table 7 - continued AneMor.athodus n • ■P * Ellisonla n. ■P. Keoaoothodus Neooondolella n.sn. Xaniopnathus tribulospa

5 * 3 ip l* A l A2 A3 H 0 P F A l A2 A3 H 0 T arcucrlstatus d lv e ro e n s W F A l A2 A3 N 0 P F

72JG -1 1 1 2 1 2

10 1 1 2 2 3 2

24 1 7

52 1 2 1 8 2

62 1 1 15 7R/ u

104 1 1 3

119 4

127 1

151 1

179 2

200 1

212 1 5 6 3 1 1

286 2 5 4

296 12 11

310 7 1

372 1 5 17 16 2 1

405 2 4 5 25 21 23 2 2

418 2 2 2 19 24 25 2

434 1 1 9 10 13 1 3

450 1 3 1 7 2 1 1 1 •O 4

474 1 3 4 6 1 485 1 1 6 7 2 1 I 2 1 507 8 179

Table 8 Conodont element distribution by sample - Phalen Butte Anehiqnatfcodus n .s p ♦ E l l i s o n i a n . sp . Keosnathodus Naoqondolella n.ap. Xartl«nat}iu» trlbuleaua 7

Sample Al A2 A3 N 0 P r A l A2 A3 N 0 T arcucristatus d iv a rq e n a K P A l A2 A3 0 P r A3

73 jg (c o n td )

530 1 1 2 7

538 1 12

€70 1 3 2 13

63 0 3 648

665 2 1 1 1 686

701 180

Table 8 - continued . AncMonathodvis n ,8 P E l l i f o n ia n . Neoapathodus iL . Heoqondolella n*«o. Xanioqpatbus tribule 5US 0

S m p l« A l A2 A3 N 0 P F A l A3 A3 K 0 F areueristatus d iv e rp e n a w F A l A2 A3 N 0 P F

71JD -1 - --

5 ------_-

10 ------

15 - - - -- » ------30 1 1 1 1 1 3

34 1 11

40 1

45 ------

50 ------

55 ------60 ------~ 65 - ----

70 - - --

75 ------* - -.- m * BO 7

B5 -- _

93 3 3 3 20 4

95 1 2 2 19

100 1 9

105 3 1

110 -

115 -- -

130 - -_ _

125 * _ _

130 “ - - 135 - ■ - w - -- - - 181

Table 9. Conodont element distribution by aample - Southern Pequop Mountains Anchionathodus n *»P E l li s o n la n . *P. Neos^athodua N. Keoqondolella n.flD. Xanioanathua t rib -Icius 7

Sam ple A l A2 A3 S 0 P r A l A2 A3 H 0 F arcucristatus d lv e rq e n s w F A l A2 A3 X 0 p F A l

71JD (c o n td )

145 -- - -

166 1

170 ----

175 1 2 180 1

203 --- -

210 -- - -

215 182

Table 9 - continued PLATE I

All figures are unretouched photographs of uncoated speci­ mens X128 except figures 16, 18, 21 and 22 which are X64.

Figures

1-5, 8 Anchignathodus n. sp. Sample 72JH-175. ^pos­ terior view of A^ element, O.S.U. 31314; 2-3~lateral view of O elements, O.S.U. 31315, 31316; 4=lateral view of P element, O.S.U. 31317* 5-lateral view of element, O.S.U. 31318; 8=posterolateral view of A element, O.S.U. 31319.

6 , 7, Xanioqnathus tribulosus (Clark & Ethington). 9-13 6=lateral viw of A* element, sample 71JF-817, O.S.U. 31351? 7=lateral view of broken A element, sample 71JC-469, O.S.U. 31352* 9, 13=lateral views of 0 elements, 9=sample 71JC-460, O.S.U. 31353, 13=sample of 71JF-774, O.S.U. 31357; 10, ll=posterolateral views of P elements, 10=sample 71JF-870, O.S.U. 31354; ll=sample 71JF-817, O.S.U. 31355; 12=posterior view of A element, sample 71JF-1027, O.S.U. 31356.

14, 19 Neospathodus arcucristatus Clark & Behnken. lateral views, 14=sample 71JA-45, O.S.U. 31322; 19=sample 71JF-375, O.S.U. 31326.

15 Neospathodus diverqens (Bender & Stoppel). lateral view, sample 71JF-1027, O.S.U. 31339.

183 184 Figures

16-18, Ellisonia n. sp. 16=lateral view of 0 element, 20-23 sample 71JF-375, O.S.U. 31323; 17=lateral view of A element, sample 71JA-45, O.S.U. 31324; 18, 21=lateral views of A. elements, sample 71JF-375, 18=0.S.U. 31325, 21=0.S.U. 31328; 20=posterior view of A element, sample 71JA-45, O.S.U. 31327; 22=lateral view of A. element, sample 71JF-375, O.S.U. 31329; 23=posterior view of N element, sample 71JA-45, O.S.U. 31320. 185 V *

1 . 1

«*L *

I

tk

♦ / PLATE 2

All figures are gold coated scanning electron microscope photographs

Figures

1-9, 11, 14 Neogondolella n. sp* l=basal view of small element X220, sample 71JF-774, O.S.U. 31341; 2=lateral view of small element X220, sample 71JF-774, O.S.U. 31342; 3=basal view of inter­ mediate element X170, sample 71JF-675, O.S.U. 31343; 4=lateral view of intermediate element X170, sample 72JG-418, O.S.U. 31344; 5=top view of large element X105, sample 71JC-444, O.S.U. 31345; 6=lateral view of large element X105, sample 71JC-444, O.S.U. 31346; 7=basal view of large element displaying basal cavity fill X105, sample 71JC-469, O.S.U. 31347; 8=lateral view of large element displaying basal cavity fill X105, sample 71JC-469, O.S.U. 31348; 9=basal view of large element with posterolateral ridges X105, sample 71JF-774, O.S.U. 31349; ll=top view of large element with posterolateral ridges X105, sample 71JF-774, O.S.U. 31350; 14=surface ornamentation of figure 11, XI100.

10, 12, 13 Neospathodus arcucristatus Clark & Behnken. Sample 71JA-45, 10=basal view showing well developed posterior process X140, O.S.U. 31332; 12=top view X150, O.S.U. 31322; 13=lateral view X150, O.S.U. 31331.

186 187 Figures

15, 16 Neospathodus divergens (Bender & Stoppel)* 15=latera'1 view X235, sample 71JF-1027, O.S.U. 31339; 16=basal view showing lack of posterior process X215, sample 72JH-1160, O.S.U. 31340. 188

PLATE 2 PLATE 3

All figures are gold coated scanning electron microscope photographs.

Figures

1, 2 Unassigned A ? element. l=posterior view? XllO, sample 71JC-444, O.S.U. 31359; 2=top view X145, sample 71JF-817, O.S.U. 31360.

3# 4, 9, Xaniognathus tribulosus (Clark & Ethington). 13 3=posterolateral view of P element X145 (same as figure 11/ Plate I); 4=lateral view of A element X170 (same as figure 6 / Plate I, but from opposite side); 9=posterior view of N ele­ ment displaying prominent posterior lip X200/ sample 71JF-817/ O.S.U. 31358; 13=posterior view of A 2 element displaying poorly developed posterior lip X200 (same as figure 12/ Plate 1 ).

5-8, 10 Ellisonia n. sp. 5-7/ 10, 17=A^ elements. 11, 5=lateral view X140 (same as figure 17, Plate 14-18 I); 6=posterior-top view X145, sample 72JH-1055, O.S.U. 31334; 7=posterior view X110 (same as figure 20, Plate I); 10=anterior view X140, sam sample 72JH-1055, O.S.U. 31334; 17-basal view of posterior process displaying slight asymmetry X240, sample 72JH-1065, O.S.U. 31337; 8 , 11, 15, 16, 18=N elements. 8=anterolateral view X170, sample 71JA-15, O.S.U. 31333; ll=anterior view X120, sample 71JA-45, O.S.U. 31335; 15=posterior view X170, sample 71JA-15, O.S.U. 31330; 16=pos- terior view X240, sample 72JH-1065, O.S.U. 31336; 18=posterior view X145, sample 71JA-45, O.S.U. 313 38; 14=anterobasal view of A^ element X135 (same as figure 21, Plate I). 189 190 Figure

12, 19 Anchignathodus n. sp. N elements, sample 72JH-175. 12=posterior view X220, O.S.U. 31320; 19=anterior view X240, O.S.U. 31321. 191

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