PALEONTOLOGY AND PALEOENVIRONMEXT

OF TME JAXES GRAVEL QUARRY,

CROSBY COUNTY, TEXAS

by

DAVID D. PROCTOR

A THESIS

IN

GEOSCIENCES

Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirei ients for the Degree of

MASTER OF SCIENCE

Approved

Decei iber, 1980 f /i—

'r' I

^ÎCO TABLE OF CONTENTS

LIST OF FIGURES iv

LIST OF PLATES v

• I. INTRODUCTION 1

Setting 1

Scope of Study 2

Objective and Statement of Problems 3

Methods of Study 3

II. PREVIOUS INVESTIGATIONS 6

Taphonoray 6

Geology 12

Paleontology 15

Stratigraphic Position 19

Age 24

III. GEOLOGY OF THE JANES QUARRY 28

Physical Stratigraphy 28

Environment of Deposition 33

IV. PALEONTOLOGY OF THE JANES QUARRY 35

Faunal Content •. 35 Faunal Interpretations 42

V. BIOSTRATIGRAPHY AND AGE OF THE JANES QUARRY 44

Biostratigraphy 44

Age 44

VI. TAPHONOMY OF THE JANES QU.\RRY 46

Taphonomic Observations and Interpretations 46

Evaluation of Taphonomic Procedures 49 ii VII. RECONSTRUCTION OF PALEOENVIRONMENT AND CONDITIONS

OF INTERMENT 52

VIII. CONCLUSIONS 54

LIST OF REFERENCES CITED 56

PLATES 62

111 LIST OF FIGURES

Figure

1. Voorhies Dispersal Groups 11

2. Composite Stratigraphic Section of the Pliocene Formations

on the Southeastern Llano Estacado 14

3. Wood Committee Provincial Ages 21

4. Stratigraphic Sections 30

5. Fauna of the Janes Gravel Quarry 36

IV LIST OF PLATES

Plate

1. Map of the Janes Gravel Quarry 64

2. View showing modem quarry wall 66

3. Stratigraphic Section 1 66

4. Stratigraphic Section 2 68

5. Stratigraphic Section 3 68

6. Clay drapes on braid bar islands 70

7. Close up of sand filled dessication cracks in the clay

drapes of the braid bar island 70

8. Overview of right maxillary of Osteoborus validus frora

the collection of Mr. Robert Morrow 72

9. Gomphotheriura raandible frora the collection of Mr. Robert

Morrow 72

10. Crushed skull of Goraphotheriura (TTU-P-9500) 74

11. Upper and lower cheek teeth of Pliohippus sp.

(TTU-P-9502-9507) 74

12. Upper cheek teeth of Neohipparion sp. (TTU-P-9508-9511) ... 76

13. Right upper cheek teeth of Neohipparion sp. frora the

collection of Mr. Robert Morrow 76

14. Diagrara of u.pper horse tooth 78

15. Isolated upper tooth of Nannippus sp. (TTU-P-9512) 80

16. Mandibular fragment of an unidentified rhinocerotid

(TTU-P-9513) 80

17. Partial left ramus of Megatylopus sp. (TTU-P-9514) 82

18. Canon bone frora a large camel cf. Megatylopus sp. from

the collection of Mr. Robert Morrow 82 V CHAPTER I

INTRODUCTION

In the spring of 1974, the Division of Vertebrate Paleontology of the Museum of Texas Tech University was alerted to an extremely large concentration of bones at a local gravel quarry. At the request of the operators of the Janes Gravel Quarry, a group of students inspected the deposit. At this time it was noted that the faunal remains consisted mainly of proboscidean and equid fossils occurring in a coarse sand and gravel sequence. In the fall of 1974, another team of students, under the direction of Dr. Pat Rich, revisited the locality. As the locality represented an ideal taphonomic occurrence, it was decided that the writer should pursue such a study as part of his Master's prograra.

Setting

The Janes Gravel Quarry is located nine and one quarter miles east of Slaton, Texas in the southwest portion of Crosby County. Lying 150 feet below the flat plain on an erosional bench, the quarry site occurs on the southwest side of the headward eroding canyon of Yellowhouse

Draw. This erosional bench, which represents the resistant basal section of the Bridwell Formation, can be traced for railes along the eastern edge of the escarpment (Frye and Leonard 1957) .

Within the quarry, the bone bearing gravels occurred approximately

21 feet below the surface. Quarry operators encountered the bones while clearing overburden above their paying gravels located between approximately 26 and 50 feet below the original ground surface. The fauna seemingly was Pliocene in age, but whether it belonged in the Clarendonian or Hemphillian land raararaalage s was not immediately apparent.

From discussions with heavy machinery operators it was possible to reconstruct an original probable extent of some 31 acres (Plate 1).

These inforraants, among whom were a number of araateur collectors, also indicated that the nature and content of the bone bed had been similar throughout its entire extent (i.e. large quantities of 'elephant' and horse bones). Tnis in itself was a cause for considerable wonder because the norraal habits of modem elephants seeraed to preclude the possibility of such a large concentration of individuals in one place.

Scope of Study

The original questions posed for this study were based on the assuraption that the biostratigraphic relationships and paleoenvironment of the Pliocene Ogallala Forraation were reasonably well understood, and that the only unique problera for study was the taphonomic history of the bone bed itself. After the initial fieldwork, however, a scan of the local geologic and paleontologic literature indicated that much confusion exists. In fact the relationship between the two local forraations within the Ogallala Group, the Couch and the Bridwell, in areas other than their referenced type areas was poorly understood.

The coincidence of the two majpr Pliocene faunal ages, the Clarendonian and the Hemphillian, with these two forraations could not be assumed, and the paleoenvironmental reconstructions were raerely untested assuraptions.

These problems led to a rapid restatement of the study. Qbjective and Statement of Probleras

The objective of this study is to derive and present a paleo- environraental reconstruction of the tirae at which the bone bed in the

Janes Gravel Quarry was deposited. In order to do this, the following questions were posed:

1. What is the stratigraphic position of the fauna?

2. What is the content of the fauna?

3. Víhat is the actual age of the fauna?

4. How did the faunal elements become interred?

5. What was the idepositional environraent?

An additional procedural problem was formulated during the planning of the research.

6. Can the taphonomic concept of investigating the

relationship of the faunal elements to the sediments

in which they occur be used as a procedural approach

to paleoenvironraental reconstruction?

Methods of Study

With the above probleras in raind, the writer proposed that taphonomy be utilized as an approach to the fieldwork. Vertebrates and vertebrate associations can be highly reflective of local environ- ment, while clastic sediments are also indicative of both the local depositional environment and the general source area frora which they are derived. The taphonomic procedure provides data on both areas.

The variety of observations and measurements which should be made during a careful taphonomic study have been sumraarized by Munthe and

McLeod (1975) . In addition, Munthe and McLeod (l^T'S) developed a series of forms to be used to facilitate the making of observations both on recent and fossil specimens. Collection of this extended amount of data reflects an optiraum research situation, but there was not enough tirae to make all these observations at the Janes Quarry. In order to fit conditions at the quarry, a two stage field procedure was developed

At two different times quarrying activities were shifted from promising fossiliferous areas to allow the writer to salvage as rauch raaterial as possible. Both periods occurred during regular seraesters and therefore fieldwork had to be conducted between classes or done on weekends. The action of the earth stripper resulted in almost total destruction of the faunal material, thus the initial goal was the excavation of specimens that would document the content and age of the bone bed for later workers. With a limited crew of two or three individuals, only sraall areas could be cleared and worked. In these . areas bone orientation was raapped on all pieces large enough to raeasure. Only identifiable specimens were collected. In addition approximately a ton of the sediment was collected and wet screened in an attempt to locate small animal remains.

In order to recover data during norraal quarrying activities another approach was used. Two prominent points, that were a substan- tial distance apart, were used as stations from which bearings were taken in areas that were being stripped. As faunal material appeared, bearings to each of these points were taken with a Brunton Compass.

The intersection of the two rays marked the location of the specimen.

From the earlier, more intensive excavations it was known that most of the fauna consisted of proboscidean, equid, caraelid, and rhino- cerotid remains, and (where possible) faunal eleraents were identified in place and orientations were raeasured with a Brunton Compass. In addition, an observation on the stage of wear exhibited by the dental elements was raade. Using this technique it was found that one person could make notes on apprximately one quarter of the material exposed by the stripper, while two persons could record as much as three quarters of the material as it was exposed.

These simple, rapid raethods were not designed to produce vast quantities of data on which to base hypotheses concerning the nature of the bone bed. Rather they were intended to produce data which would allow the testing of tentative hypotheses already developed from

inforraation gathered during the first stage, intensive excavations.

In addition to the collection of faunal inforraation, there was also an eraphasis on the collection of sediraentological data. A series of stratigraphic sections were measured and described. Observations and interpretations were raade where possible in the field. Samples of the sand and gravel were taken and later examined to determine mineralogical content. CHAPTER II

PREVIOUS IN'VESTIGATIONS

Taphonoray

Many geologists and paleontologists are not familiar with the

concepts of taphonoray. This new procedure is the basis for the entire

work in this project, and therefore a brief summary of the concepts is

in order.

Taphonomy, as defined by Efremov (1940), refers to the 'laws of

death' or the factors which have operated on specimens of a fossil

assemblage from the time of death of the individuals to final interment

in the deposits in which they are found. The development of this con-

cept has been in response to the recognition that most fossil assem-

blages are much different in aspect than the original biological com-

munities from which they were derived. The modern techniques of

taphonomy, which focus on mode of death, predation, transport, sorting

and diagenesis, are used to eliminate as much of this sample bias as

possible before paleoecological reconstruction.

Most taphonomists would consider this subdiscipline to be a very

new part of vertebrate paleontology, but these factors have been rcc-

ognized as important for most of the history of the discipline (for

example see Case (1919) for an intercsting discussion of thcse probleras)

Modern systematic work in this area began in the 1960's in

response to work by Shotv/eil (1955, 1956) some ten years earlier. In

this work he realized that in the analysis of fossil quarry assemblages one must be able to calculate minimum numbers of individuals and be

able to recognize specimcns from distant ecosystems that might have 6 been transported into a deposit. Shotwell's conclusions and the assumptions on which they were vased were imraediately questioned by other workers.

During their work on Oligocene faunas of the Brule Formation frora the Big Badlands of South Dakota, Clark and Kietzke (1967) found it necessary to suramarize theoretical difficulties inherent in the analysis of vertebrate faunas. Prior to their analysis. they listed four observations which they considered as a necessary base to any discussion of saraple bias.

1. No coraplete census of a living undisturbed mamraalian

coraraunity has ever been raade, and therefore there is

no rigorous way to judge raodificationswithi n a

fossil asserablage.

2. Although the fossil asserablage obviously represents

a saraple of a once living population. there is no

way to extiraate the size of the original population

and thus the significance of the sample.

3- Statistical analysis of 'nonrandomly' selected

assemblages is meaningless.

4. The fos.sil assemblage is not a direct saraple of the

fossil population.

Beginning with a living paleoecological comraunity and continuing through to the curation of a fossil assemblage in a museura, Clark and

Kietzke (1967) postulated that there are seven sarapling stages which operate on all faunas. These are as follows.

1. The biotic factor relates to conditions of life hab t

and skeletal structure that could influence the inclusion of an individual or a species in a death assemblage (thanato-

coenose). They cite range, habitat, population density,

skeletal morphology and body size as examples.

2. The thanatic factor includes all elements of the mode of

death of an animal or group of animals. This would include

cause of death, type of death íattritional versus catastrophic

mortality), and initial death position.

3. Perthotaxic factors operate between death and transport and

include weathering and scavenging.

4. Taphic factors relate to the moveraent of potential fossils

and their incorporation into a body of sediment. Critical

factors include the method of introduction into a streara,

the type of stream, the hydrodynamic characteristics of

the bone, and the susceptibility of the sediment body to

reworking.

5. Anataxic factors refer to post depositional diagenesis which

raay result in the destruction or alteration of bone within

the sediraent body.

6. Sullegic factors include methods of collection, biases of

the collector, time available for collection, and the extent

to which the deposit has been previo.usly sampled.

7. The trephic factor relates to curatorial biases. Included

here are collection manageraent procedures, the training level

of the identifier, and his personal biases.

The preceding seven factors represent the most ariticulate and careful assessment of the sampling problems in vertebrate paleontology.

These factors operate sequentially and Clark and Kietzke (1967) clearly understand that at best the fossil assemblage represents a sample of a

sample of a sample. The statistical universes from which these samples

are derived can never be completely reconstructed.

More recently work has been added in the areas of the thanatic and

taphic factors. These areas lend themselves to more quantifiable

procedures, and there is now a tendency to consider these areas to be

the entire realra of taphonomy.

Voorhies (1969) in his work on a Clarendonian locality from

Nebraska, emphasized the use of sedimentological data in taphonomic

reconstructions and demonstrated the use of bone orientation in

paleocurrent analysis. In the operational portion of this paper

Voorhies (1969) emphasized the raodes of death and the hydrodynaraic

actions of the bones.

Voorhies (1969) recognized two raajor types of death. These were

attritional raortality and catastrophic death. He was able to distin-

guish between thera on the basis of normal population distribution data.

Attritional mortality refers to the normal deaths which can be

expected to occur in a given period of time. In terms of age groups of

a population, there will be a bimodal preference shown in this type of

death occurrence. One will expect to find very old members of the

population and the very young. Both of these groups show a decreased

ability to cope with environmental stress in comparison to the mature

members of the group. Osteologicfllly the response to tbis bimodal preference translates as a preponderance of the incorapletely fused

skeletal elements of the young and the arthritic, wom eleraents of the old.

In catastrophic death situations the opposite will tend to be the 10 case. With this occurrence a whole cross section of the population is

produced and elements from normally viable adults, whose members are

usually equal to the combined number of young and old, will predominate.

Voorhies (1969) also believed that differential transport of

skeletal elements represented one of the raajor biases in a fossil

assemblage. At the same tirae he realized that it represented a problem

on which quantitative data could be gathered. In the first iraportant

streara table study of the distribution and orientation of bones in

stream environments, he made some interesting and significant obser-

vations.

Working with a variety of skeletons, mostly of coyote and sheep,

he was able to establish a series of groups based on their hydrodynamic

characteristics (Figure 1). iowledge of the susceptibility of

different bones to transport led Voorhies (1969) to suggest that alluvial

accuraulations of bone could be corrected back to a reasonable descrip-

tion of the original sample.

In his examination of the stream table orientation data and his

comparison of these data to similar observations made on actual fossil

specimens in his Verdigre Quarry, Voorhies (1969) determined that long bones showed two preferred orientations. He noted that these bones becarae oriented transverse to current direction when water depth left them partially exposed, and there was a preferred longitudinal orientation in water depths that completely covered the bone. He also noted in passing that small bones were occasionally trapped with a transverse orientation in the troughs between ripples. In contrast to his own fossil quarry observations, he found that in almost all experimental cases bones reraained effectively horizontal. 11

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The investigations of Clark and Kietzke (1967) and Voorhies (1969) have stimulated a recent surge of interest and work in taphonomy. The raore iraportant of these contributions include; Behrensmeyer Í1975),

Dodson (1971, 1973), Munthe and McLeod (1975), and Wolff (1975). Their work has served to focus the attention of taphonomists on the operational procedures which can be used in taphonomic analysis.

Geology

The Tertiary of the Southern High Plains is confined to a single,

relatively flat sheet of Miocene-Pliocene gge sediments. These sedi- ments, which represent the southern extension of the typical Ogallala

sediments of Kansas and Nebraska, are locally derived frora the under-

lying bedrock and mountain sources to the west and northwest (Frye and

Leonard 1957). The Ogallala sediments of West Texas rest unconformably on Permian, Triassic, and Cretaceous rocks. These sediments have completely infilled all pre-Tertiary tonography.

The history of geological investigations of the Ogallala Formation has heen suraraarized recently by Frye and Leonard (1957, 1959, 1964) and

Schultz (1977) in papers dealing with the floral, molluscan and verte- brate assemblages of West Texas. They point out that the original explanation for the widespread occurrences of Tertiary sediments, which favored a lacustrine origin, was rapidly discarded in favor of the idea that these sediments were the result of coalescive alluvial fans coming directly off the raountain fronts (Johnson 1901, Plummer 1955). Recently an obvious flaw with this theory, the nature and angle of the beds, has been pointed out (Frye, Leonard and Swineford 1956). They indicate that the Ogallala may be interpreted as a number of broad river channels 13 which have subsequently coalesced (see review in Frye (1959)). This has subsequently been shown to be correct only for the northern portion of the Llano Estacado because the southwestem portion shows eolian rather than alluvial deposits (Reeves 1972).

Evans (1949) described two distinct formations within the Tertiary sediments of the central portion of the Llano Estacado. They were defined on the basis of a prominent unconformity that Evans (1949) recognized in the deposits. Evans (1949) further suggested that the term Ogallala be assigned to the name of the group of Tertiary formations in this area. The new formations were named the Couch and the Bridwell after ranches where the deposits were well exposed.

The Couch Formation, as defined by Evans (1949), is the lowest

Ogallala unit in the central Llano Estacado. It rests unconformably on underlying Cretaceous and Triassic Formations (Figure 2), and during the time it was deposited it infilled all preexisting topography. It is characterized by a basal sand and gravel section. Overlying these coarse grained channel deposits are light, pinkish, finer grained calcareous sands and clay. A caliche or thick occurrence of calcium carbonate occurs at the top of the formation. Vrnile variable in thickness, the Couch locally attains a thickness of up to 125 feet.

Above the unconformity recognized by Evans, the Bridweil Formation exhibits a similar sequence. Again there is a coarse basal gravel.

The basal gravels, consisting of quartzites from the Sangre de Cristos

Mountains of New Mexico and caliche pebbles from the Couch Formation

(Foster 1952), are overlain by a thick section of sands and clay with small lenses of gravel. The maxiraura thickness of the forraation is approxiraately 160 feet, and a general upward fining occurs throughout. 14

• -+ 1 Period Epoch Formation Lithology Thickness r i1 1 Pleistocene Pleistocene cover í sands 1 1

1 i

T B 1 i 0 R Caliche i 1 ; E I approx. 1 P G D 155ft. • R L W Sands, clays and I A E some gravel lenses i 0 L 1 ] C L L 1 i I E Coarse sands and 1 t N L gravels i A E í A ' R 1 1 t 1 L • Y A C Caliche 1 0 1 1 u ! approx. c Fine sands and i 125ft. H gravels

•' ' Miocene Coarse sands and ! gravels i

MESOZOIC SEDIxMENTS

Figure 2: Coraposite stratigraphic section of the Pliocene Formations on the Southeastem Llano Estacado 15

A dense caliche occurs at the top of the forraation. This caliche, locally known as the Caprock Caliche. forms the resistant bed that protects and npholds the plateau of the Llano Estacado.

More recent workers on the Tertiary of the Southern High Plains

(Frye and Leonard 1957, 1959 and Van Siclen 1957) have suggested that the unconformity between the two formations on which Evans (1949) based his original definition is not as prominent as he thought at the time.

These workers have suggested retaining the nomenclature used elsewhere for the Ogallala. Thus it would remain a formation and the Couch and the Bridwell would be reduced to the level of merabers.

The current interpretation of the Ogallala in this area (Frye and

Leonard 1957, 1959, Pierce 1978 and Schultz 1977) is that these deposits represent a series of broad river valleys which coalesced during the

Pliocene. Materials in the lower portion of the section are derived frora the local underlying carbonates. In the Bridwell section these clastics are augraented by the addition of quartzites frora the metamor- phosed core of the Sangre de Cristos Mountains. The caliches at the top of both the Couch and Bridwell sections are interpreted as petro- calcic horizons of paleo-mollisols.

Paleontology

Systematic collecting of vertebrate fossils on the Llano Estacado began in the 1890's when Cope (1893) presented an inventory of the localities and their conten as known at that tirae. Using the vertebrate fossil record, Cope (1893) was able to confirra a Cenozoic age for the

Ogallala sediments of West Texas, an idea which had been advanced earlier by Cummins (Frye and Leonard 1959). At this time Cope recognized three fossil bearing deposits on the Llano Estacado.

In an area north of the South Fork of the Red River, where the present town of Clarendon is located, Cope recognized expo'^iires of what he considered Miocene age 'Loup Fork Beds'. In these sediments he noted the occurrence of Tetrabelodon, Aphelops. Protohippus, Procamelus, and

Blastomeryx. He pointed out that there were no rodents or lagomorphs in the fauna. He attributed this to a lack of the facies in which these forms probably lÍA/ed.

To the south, he recognized and collected another deposit near

Mount Blanco. These Blanco beds were clearly younger than his 'Loup

Fork Beds', and he reported thera to be Pliocene in age. Jn these beds

Cope identified Megalonyx, Caniraartes, Borophagus. Felis, Tetrabelodon,

Dibelodon, Equus^ Platygonus, and Pliauchenia.

In Tule Creek Cope (1893) located even younger raaterial which now would be considered Pleistocene in age. In these 'Equus Beds' as he naraed thera, he found Mylodon, Elephas, Equus and Camelog^.

During his work in the Panhandle, Cummins had located a fauna near Goodnights in the vicinity of Palo Dnro Canyon. He very carefully noted that this faunal material was younger than the 'Loup Fork Beds' becanse it occurred in deposits directly over a coarse conglomerate which could itself be mapped directly above the 'Loup Fork Beds' near

Clarendon- Cope (1893) examined this material and identified speciraens of Protohippus lenticularis, Protohippus perditus, Hippidiura interpolatum,

Equus eurystylns and Aphelops. He agreed that this fanna was definitel;V yonnger than the 'Loup Fork Beds' material, and he considered it Late

Miocene in age.

From 1899 to 1901 the American Museum of Natural History supported expeditions to the area under the leadership of J. W. Gidley (19031.

He associated the Texas Ogallala sediraents with the 'Loup Fork Beds' to the North, considering thera Miocene in age. He disagreed with Curarains concerning the Goodnight fanna and considered it equivalent to other

'Loup Fork' faunas. He inferred that the Blanco fauna occurreH in

Pliocene sediments that were imposed on top of the Miocene deposits.

Working in raany of the same localities as Cope, Gidley added new taxa to the faunas. Revision of the equids led him to ascribe many speciraens that Cope had considered to belong to the genera Protohippus and Equus to the genns Neohipparion.

During the years frora 1927 to 1929 Reed and Longnecker were engaged in raakine a geologic survey of Hemphill County, Texas [Matthew and Stirton 1930b and Hesse 1940). In the course of their work they encountered a nuraber of vertebrate localities and their raaterial was donated to the University of California Museum of Paleontology. During the summers of 1929 and 1930 parties from the University of California,

Berkeley collected frora these localities.

Matthew and Stirton (1930b) published an account of the horse raaterial from these localities, principally locality 20. They indicated that this fauna was distinctly younger than the Clarendon faunas and older than the Middle Miocene Blancan fauna. They therefore assigned the Hemphill faunas to the late Early Pliocene. They interpreted the bone beds to be the results of miring and catastrophic burial in river channels, and they again noticed the absence of rodents and lagomorphs.

Like Cope they attributed this to life habits which would preclude their inclusion in channel deposits. They also pointed out an often neglected fact: the deposits in which these faunas are located record very special 18 circumstances, and therefore such faunas might not be 'normal' to the area.

Within their material, Matthew and Stirton (1930b) identified

Pliohippns interpolatus, Protohippns ansae, Hipparion (Neohipparion) eurystyle, and Hipparion (Nannippus) lenticulare. Ouring ?.n attempt to corapare these forras with other Panhandle faunas they found their matpripl to be raost closely allied to the Goodnight material and substantially advanced over the typical ' Loup Fork' material coUected by Cope and Gidley. This work seeraed to validate Cumrains' originai assuraption concerning the Goodnight fauna.

At the same tirae thîít the Hemphill localities were found, ReeH and Longnecker examineri another vertebrate locality near the town of

Higgins in Lipscomb County, Texas. Vae University of California also collected material from this HTggins locality (Hesse 1940). The faunal material from this locality occur^^ in a coarse gravel senuence similar to the section exposed at the Janes gravel quarry (Dr. Gerald Schultz,

Personal Coramunication, 1978). Hesse (1940) reported the occurrence of

Osteoborus cynoides, Osteoborus validus, Machaerodus catacopis,

Neohipparion occidentale, Pliohippus sp., Teleoceras cf. fossiger,

Aphelops malorchinus, Mf^ry^odus or Capromeryx, ^ camelid and specimens of an unidentified proboscidean which was the raost comraon raaterialfror a this locality. Johnston (1939) pnblished a raore detailed discussion of the Osteoborus validus material.

More recently published work'í on the Ogallala fauna of the Llano

Estacado are rare. Evans (1949) had a liraited araount of material available to hira when he described the Couch anH Bridwell forraations.

Johnston and Savage (1955) raentioned four late Heraphillian localities 19 in their discussion of Late Cenozoic faunas in the Texas Panhandle.

Schultz (1977) has recently summarized the bulk of the vertebrate paleontologácal work for the Panhandie of Texas.

Stratigraphíc Position

The initial work on dí^ting the Ogallala has already been mentioned in the preceding discussion of the history of collecting in the area.

Cummins (1893) was the first person to advance the Tde^ that the Texas

Ogall^la was Tertiary in age. Cope (1893) and Gidiey (1903) both non«íidered these sediments to be Miocene in age, and in one of the first attempts at correlation of the Tertiary mamraalian faunas of Western

North America; the ' Loup Fork Beds' were considered to b'^long in the

Middle Miocene while the Clarendon beds were assigned to the Upper

Miocene (Osbom and Matthew 1909). The Blanco beds were designated as being of Middle Pliocene age.

At the tirae that the horse faunas of Heraphill County were described

(Matthew and Stirton 1930b), the Clarendon Beds, recognized as part of the earlier 'Loup Fork Beds', were considered to be earliest Pliocene while the Hemphill beds were considered to be late Early Pliocene in age. This change was due to an arbitrary decision on the part of

Matthew and other workers to consider the appearance of Hipparion type horses as the beginning of the Pliocene (R. Wilson. Personal Coraraunica- tion, 1978). At this tirae the Blanco beds were stiU placed in the

Middle Pliocene.

Probleras with the age of Tertiary faunas continued and more attempts at correlation were made (see Simpson 1933 for exaraple).

Stirton (1936) published a correlation of all North Araerican Pliocene 0

faunas. At this time he believed that the Clarendon beds were late

Early Pliocene in age. He considered the Higgins fauna to be of eariy

Middle Pliocene age and the Heraphill and Goodnight faunas were placed

in the late Middle Pliocene. Interestingly enough, he considered the

Blanco fauna to be Late Pliocene, a position which was in opposition to

the norraal placeraent of tnis fauna in the Middle Pliocene by the United

States Geological Survey. This however was not to be the iast attempt

to produce a standard sequence for American mammalian faunas.

In 1941 an attempt was made to characterize the entire Tertiary

Period of the United States in a series of successive mamraalian

Provincial Ages (Wood and others 1941). These Provincial or Land

Maramal Ages were based on a combination of four factors; first and

last appearances of certain fossils, index fossils which were thought

to be restricted to a singie Land Mammal Age and the characteristic

fossils which were comraon to most faunas of that age.

These Land Mammal Ages, while covering the entire Tertiary Period,

were intended to be separate from actual rock and time units (Tedford

1970). In practice, however, this was not the case. Many of the Land

Mammal Ages were labeled with the naraes of specific formations or

formally associated with them. Also at the last moment the Wood

Coramittee decided to indicate the position of their Land Mammal Ages

in terms of the normal Lyellian Epochs (Figure 5). While each Epoch was characterized by more than one Land Mammal Age, none of these ages was indicated as straddling the arbitrary epochal boundaries. This fixation of the sequence within the Lyellian Epochal system, which was completely contrary to the original intent of its authors, raised as many problems as it solved and led to the same problems in discussion 21

Lyellian Provincial Epochs Ages

Blancan

Pliocene Hemphillian

Clarendonian

Barstovian

Miocene Hemingfordian

Arikareean

Whitneyan

Oligocene Orellan

Chadronian

Duchesnean

Uintan

F.ocene Bridgerian

Wasatchian

Clarkforkian

Tiffanian

Paleocene Torrejonian

Dragonian

Puercan

Figure 3: Wood Committee Provincial Ages that it had been designí^d to solve.

The three îand Mammal Agf»s proposed by the Wood Committee for

the Plioc^ne Fpoch included the same faunas that Stirton (1936) had

described five years earlier. They defined three faunal ages on the

basis of coUections frora West Texas and the Texas Panhandle that have

been previously discnssed. They nam.ed these Ages the Clarendonian, the

Heraphillian, and the Blancan. The Clarendonian and Heraphillian fannas

were thought to occur in the Ogallala while the Blancan was inferred to

represent post Ogallala sediments.

The Clarendonian Land Mammal Age was defined on the basis of the

raaterial from the Clarendon local fanna of Donley County in the Texas

Panhandle as defined by Simnson (1933) and Stirton (1936). Using tbe

four criteria mentioned ahove, the following fauna was proposed as

indicative of the Clarendonian Land Mamraal Age. Index fossils included

Eucastor, Megahippus and Synthetoceras. They IJsted under first

appearances the following forras; Hipparion. Neohipparion, Pliobippus.

Nannippus, Megatylopus, Pliauchenia, Serridentinus, and Sphenophalos.

Forras making their last appearance were Aelnrodon, Amphicyon, P1iocyon,

Calippus^ Hypolagus, Merchippus^ Alticamelus, Procam.elns, Merycodus,

Metoreodon, and Cynodesraus. Aphelops, T^leoceras, Prosthenops, Osteo-

borus and Mylagaulus were considered characteristi.c fossils of this

Land Mammal Age.

It is possible tn characterize the Cl?rendonian as the intí^rval

in which pliohippine and hipparion hnrsí^s appear and are found in association with •••he remnants of the Merychippine horses. Also it is the last time that oreodons are found in North American faunas as well as the last appearance of the antilocaprid, Merycodus. In the Tevas J5

Panhandle the smaller aniraals are poorly represented because they prob- ably did not live in areas which contributed to the channel deposits that are preserved in the area. In addition, as noted by Dodson (1973), these forms are easily transported by streams long before they have a chance to become disarticulated or deposited.

The Hemphillian Land Mammal Age was based on material from the

Hemphill Member of the Ogallala Forraation, principally frora the Coffee

Ranch and Higgins Quarry faunas of Heraphill and Lipscorab Counties of the

Texas Panhandle. Agriotherium, Plesiogulo, Dipoides and Ilingoceras were listed as index fossils. First appearances included Machaerodus,

Taxidea and Lutravus, while last appearances included .Aphelops,

Teleoceras, Pliohippus, Pliauchenia, Prosthenops, Sphenophalos,

Blastomeryx, Qsteoborus and Mylagaulus. Hypolagus, Megatylopus,

Nannippus and Neohipparion were listed as characteristic fossils.

The Hemphillian is very similar to the Clarendonian, except that it lacks the more primitive reranants such as the Merychippine horses and the oreodons. It is also the last tirae in which rhinos are found in North

Araerica.

When Evans (1949) divided the Ogallaia of the central portion of the Llano Estacado into two formations, the Couch and the Bridwell, he considered the Couch to be Early Pliocene and the Bridwell to be Medial

Pliocene in age. This was based on the fauna contained in each formation

Without mentioning the Clarendonian Land Mararaal Age by name, it is clear that the occurrence of Pliohippus, Neohipparion, Nannippus and

Procamelus suggested this age to him and that he accepted the Wood Com- mittee's position of this fauna. Similarly the occurrence of the small

Pliohippine genus Astrohippus indicated that the Bridwell raust be 24

Middle Pliocene in age.

Age

In the preceding portion of this chapter -the history of the stratigraphic placeraent of the Ogallala within the later Tertiary was described. It is obvious that there has been considerable controversy

concerning this problem in the past. Even today there are still problems with stratigraphic terminology and absolute age of continiental late

Tertiary sediments of North America.

The previous discussion indicates that the dating of the Ogallala has been based almost entirely on the presence of Clarendonian and

Hemphillian faunas, and it was on this basis that Evans (1949) considered the Couch and Bridwell to be Pliocene in age with the clear implication that they included much if not all the Early and Middie Pliocene.

Recent work on the absolute dating and magnetic stratigraphy of

Late Tertiary faunal bearing sediments has led to a clearer understanding of the temporal relationships between these faunas and the sediments in which they occur (Lindsay and others 1975). Transatlantic correiations using both magnetic stratigraphy and invertebrate paleontologicai information as well as vertebrate paleontology from both the North

American and European continents has reinstated the idea that much of the Ogallala raay be truly Miocene in the Lyellian sense (Berggren and

Van Couvering 1973). This, of course, represents a return to the ideas of more than three quarters of a century ago.

With the advent of the potassium-argon method of dating volcanic rocks it became possible to bracket date raany mammalian localities in

North America. Everenden and others(1964) produced a series of dates 25 on volcanic tuffs and rocks which were associated with vertebrate faunas. These dates were remarkably consistent. They indicated a maxiraura age for the oldest Clarendonian locality of 11.7 million years and a rainimum date of 9.1 million years. Datable Hemphillian localities appeared to occur between 10.0 and 5.2 million years whiie the earliest date for a Blancan fauna was some 3.5 million years. Therefore, in terms of the Wood Comraitte report that places the Miocene-Pliocene boundary at the base of the Ciarendonian, this boundary raust occur at an age of approximateiy 12 raiilion years B.P..

In addition to the absolute dating of this time period, a significant new relative dating raethod has recentiy become prominent.

Magnetic stratigraphy, the charcterization of the direction of the earth's magnetic field at the time of deposition of fine grained sediments, has been used in the Texas Panhandle to try to correlate the large number os vertebrate faunal locaiities in this area (Lindsay and others 1975). During this work it was found that the type Hemphiii from the Coffee Ranch locality is normally magnetized. With an over- lying ash date of 6.6± 0.8 million years it is probable that this normally oriented material belongs to Magnetic Epoch 5 rather than to one of the later named magnetic epochs (Lindsay and others 1975).

It has long been known that on the west coast of the United States terrestrial sediments which are considered Pliocene in age, based on their vertebrate faunal remains, interdigitate with raarine sediraents that contain invertebrate fossils norraally considered to be Miocene in age (Durhara, Jahns, and Savage 1954, Repenning 1967, and Savage and

Barnes 1972) . The problem lies with the original definition of the

Tertiary epochs. Lyell (1833) proposed the epochs on the basis of the 26 percentage of living species of moliuscs in the faunas from various sections in the Mediterranean area. He recognized 40 to 70 percent of iiving species in the beds he called Pliocene and 95 percent of living species in the beds he calied Newer Pliocene (now Pieistocene). His identifications were, in raany cases, incorrect, and the type sections he used were often subsequently shown to be of a different age than he had presuraed. Still the problem remains; how does one correiate

Mediterranean marine type sections with North American terrestrial deposits?

In Europe the faunas which contain Hipparion type horses are, in the view of many workers, interfingered with marine Miocene beds

(Berggren and Van Couvering 1973) . On faunal evidence however, it is known that these horses evoived in North Araerica. It is irapossibie that they should appear in Europe before their appearance in North Araerica.

It seeras obvious that the North Araerican faunas which contain Hipparion type horses, the Clarendonian and the Heraphillian, must be older than they have been considered for the past forty years.

This problera has been covered in exhaustive detail by Berggren and

Van Couvering (1973), and they point out that there is no totai consensus in Europe as to the meaning of the terras Miocene and Pliocene. For this reason it is best not to attempt a compiete revision of the correlative stratigraphy of the United States terrestrial sections at this tirae.

It is however, possible to make a prediction about the future consensus on the age and position of Clarendonian and Hemphillian faunas and the deposits in which they occur.

On the basis of potassium-argon dates of voicanic raateriais associated with the Clarendonian and Hemphillian, it is already L. I accepted that the earliest Clarendonian must be approximateiy 12 million years oid. Hemphiilian faunas date between 10 and 5 million years ago.

Therefore the West Texas Ogallala must have been deposited between 12 million and 5 raillion years ago. It is probabie that virtuaily the

.entire tirae period will in the future be considered Miocene, and that the Pliocene will in fact be associated only the the latest Heraphiliian and the Blancan Land Mararaal Ages. CHJ\PTER III

GEOLOGY OF THE JANES QUARRY

Physical Stratigraphy

Although the quarry lies sorae 150 feet below the flat plain of the

Llano Estacado on the resistant base of the Bridwell Formation, at ieast another 100 feet of Ogallala sediraent underly the quarry. It seems probabie that these sediments may have provided some of the materiai for the lower part of the coarse sand and gravel sequence refiected in the quarry exposures.

Within the quarry the gravel stripping operations have produced walls with up to 50 feet of exposed vertical section. In the main east-west cut (C-C' in Plate 1) this 50 foot high exposure was complete and unbroken over a distance of more than 750 feet during the Fall of

1975. There was also an additional 500 iinear feet of exposure of the lower 15 feet of the section on the east end of the cut (Plate 2). In cuts lateral to the main wall sequence deep, blocky soil sequences with extensive deposits of calcium carbonate occur, but the entire 50 foot vertical section of the raain wall represents a braided streara channel sequence of sand and gravel (See Rust and Williams 1969, Sraith

1970, 1971, Wright 1959 and Kothraann 1963 for discussions of braided streara environments). This indicates that the streara was flowing through a relatively warra, semiarid area where moUisols were forming.

The quarry exposures exhibit a number of upward fining sequences superimposed one on top of the other and a general decrease in overaii stream competency through time. The lower part of the section contains coarse gravels with cobbles up to 25 centimeters in diameter, while the 28 29 upper part of the sequence is much finer, being composed of sands, fine gravel, and clay. These relationships are iilustrated in the three stratigraphic sections (Figure 4) which have been included in this report

The first section represents an area approximateiy 200 feet west of the east end of wall C-C' (Plate 3). Section 2 was drawn at the tum of the wall near the south end of wall D-D' (Plate 4). Section 3 represents a portion of the wall after it retums to a basic east-west orientation

(Plate 5).

As mentioned above, streara corapetency, as indicated by the size of gravels, was rauch higlier during the lower part of the sequence. In an older portion of the quarry, which was excavated at ieast 3 to 5 meters deeper than the raodern quarry, streara rounded limestone boulders more than 3 meters in diameter can be seen. These were originaily thought to be huge caliche boulders but closer examination of freshly broken surfaces reveals the presence of raarine invertebrates. This indicates that the source of these boulders must have been the subjacent Cretaceous

Edwards liraestone.

Sorae 5 to 10 meters above the bottora of the old quarry in iower portions of modern exposures, fist sized cobbles are comraon with occasional layers of cobbles up to 25 centimeters in diaraeter. These cobbles and the associated gravel are coraposed of Cretaceous liraestone, individual Cretaceous bivalves of the genus Gryphaea, and caliche, presuraably from the soil at the top of the Couch Formation. This evidence clearly indicates an increase in stream competency over that which is implied by the fine, pinkish sands at the top of the Couch

Formation (Brand 1974).

In the middle of the section, quartzite gravels appear which can 30

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-^ 31 be traced to the metamorphic core of the Sangre de Cristos Mountains of

New Mexico (Foster 1952). In this portion of the section the gravels are much finer, being composed of the quartzites mentioned above, caiiche and lesser amounts of limestone and Cretaceous bivalves. Here also are found upward fining sequences of fine gravel and sand overlain by thin layers of clay (Section 1 in Figure 4). These layers of clay represent clay drapes on braid bar islands. Tliese islands or bars were subaeriaily exposed after retreat of the water and in one case (Piates 6 and 7) mud cracks formed during desiccation. The cracks subsequently fiiled with sand. Toward the top of the sequence (Sections 1 and 3 in Figure 4) the presence of two layers of calcium carbonate reflects momentary surface stability with incipient soil forraation in an aggrading sequence.

The stratigraphic section exposed by the quarrying activities presents a unique cut away view of a braid bar island. Stratigraphic section 1 (Figure 4 and Plate 6) shows the west end of the braid bar island sequence. It appears that this island was cut by a channelet

(Plate 6) or the slip off slopes from two braid bar islands were encroaching on each other. Sections 2 and 3 (Figure 4) have preserved exaraples of the channel lag gravels which were at the base of this sequence. In section 2 crossbedded sands and graveis occur below the black bone bearing gravels. The crossbedding represents a longitudinal cut along the channel and stream flow at this point was almost due east.

Above the level of the black gravel and bone bearing sand, stream direction is raore difficult to define. The horizontal bedding exhibited in the east-west wall (C-C') represents a transverse cut across a channei segment that trended north-south. The oblique cut and fill structures on the north end of the north-south wall (D-D') indicate only that this ôJ.

exposure is neither parallel nor perpendicular to stream fiow. The

black gravel above the crossbedded unit shown in section 2 (Figure 4)

is horizontal and probably represents a continuation of the transverse

view of the north-south channel. With northern New Mexico as a source

area for the Ogallala strea.ms, it seems probable that the general direc-

tion of stream flow was toward the Southeast. Within the main channel

however, the smaller channelets probably record diverse directions.

The bone bed is associated with the braid bar island sequence

described above. The exposure of the bone bed is continuous for over

900 feet, and there are discontinuous exposures for approximately 600

feet more. On the east end of the quarry, bone is found in direct

contact with the black gravel, while to the west it occurs in sands

directly above the thick clay drape and below the thin dish shaped

clay drape shown in section 1 (Figure 4). The bone is scattered through

an interval of four feet, and these sands are greenish tan in coior. In raany instances a yellow limonite band occurs at the bottom. To the west it is possible to trace the termination of this portion of the channel and determine part of its history.

The greenish tan sands end in lateral contact with a massive pink sand. This massive, uniformly fine sand continues sorae 75 feet to the west and abuts against the dense, blocky, reddish soil. This defines the edge of the main channel, and it seems that the channel deposits in which the bones occur raust have been cut down into an earlier raassive sand deposit that might represent overbank deposits of local blow sands.

Therefore one can assume that much of the sedimentation occurred in a relatively old, stable entrenched channel cut into the blocky, sandy soil of the local area. J>J

Environment of Deposition

Consideration of clastic content, sedimentary structures, and pedologic features within the Ogallala of West Texas indicates that there were two major episodes of deposition. Both episodes reflect the dominance of stream valley deposition rather than alluvial fan deposition,

Alluvial fans are poorly sorted and usually have relativeiy steeper dips than river channels owing to their proxiraity to the source area. The

Ogallala however, exhibits a very gradual dip frora Northwest to South- east of 8 to 10 feet per raile, and the sediments are localiy weil sorted. While the bulk of Ogallala sediraents are relatively coarse, the upper portion of the forraation exhibits .finer grained raeander belt sediments (Dr. A. Jacka, Personal Coraraunication, 1977). Presence of well developed petrocalcic soil horizons at the tops of both depositional episodes indicates that there were periods of iandscape stability between and after the deposition.

The Janes Gravel Quarry is located on a bench on the side of the headward eroding canyon of Yellowhouse Draw. This bench is formed by the resistant gravel base of the Bridwell Formation and can be traced for a considerable distance (Frye and Leonard 1957). The coarse nature of the sediments and sedimentary structures such as the prominent current ripple structures and braid bar island sequence indicate that the sediments exposed at the quarry represent a braided stream environ- ment.

This basal Bridwell braided stream indicates rejuvination of stream competency over that indicated by the relatively fine sands of the

Upper Couch (Dr. G. Schultz, Personal Communication, 1978). The occur- rence of black quartzite gravels in the upper portion of the exposures 54 documents the erosional breach of the metamorphosed core of the Sangre de Cristo Mountains of New Mexico.

Deposition in a stable, semiarid environraent can be documented by

both pedologic and sedimentary evidence. The dense, blocky, red-brown

local soil in which the channel was entrenched and the petrocalcic

horizons exposed in both the channel sediraents and the soii are

indications of the seraiarid conditions. This is supported by the fiiling

of the cracks in the subaerialiy exposed clay drape by eolian sands. CHAPTER IV

PALEONTOLOGY OF TOE JANES QUARRY

Faunal Content

The following discussion of the identifiable fauna frora the Janes

Gravel Quarry represents only a small fraction of the raaterial that probably exists at the quarry. In raost cases speciraens were crushed

and broken. Identification was irapossible in these cases. For every

specimen which could be identified to genus, several thousand couid not be identified at all or only identified to very broad taxonomic groups

(proboscidean, camivore etc). The writer reaiizes therefore that

the faunal list is incomplete. Further work in the abandoned portions of the quarry would surely turn up new additions to the faunal iist

(Figure 5).

As was the case with the collections of both Cope (1895) and the

University of Califomia Museum of Paleontology (Matthew and Stirton

1930b, Hesse 1940) no rodents or lagoraorphs were encountered at the

Janes Gravel Quarry despite the fact that over a ton of matrix from the two main excavations in the bone bed was washed, screened and sorted to check for their presence. Instead the fauna is confined to the sarae types of aniraals found in earlier work to the north. To date only the large herbivores that Matthew and Stirton (1930b) considered to have been subject to miring and catastrophic burial and the carnivores which presumably preyed on them have been identified in the fauna.

Order CARNIVORA

Material recovered from the quarry indicates the presence of both felids and canids. Carnivore material appears to be very scarce in the 35 36

Class Mammalia

Order Carnivora

Family Canidae

Osteoborus cf. validus Family Felidae?

Order Proboscidea

Family Gomphotheriidae

Gomphotherium sp.

Rhynchotherium sp.?

Order Perissodactyla

Family Equidae

Pliohippus sp.

Neohipparion sp.

Nannippus sp.

Family Rhinocerotidae

Gen. indet.

Order Artiodactyla

Family Camelidae

Megatylopus sp.

Figure 5: Fauna of the Janes Gravel Quarry o, deposit, and what has been found to date is extremeiy fragraentary.

Although this material appears to have belonged to reiatively iarge sized animals, they were still among the smailest members of the fauna located to date, and they have been more severeiy damaged by the heavy machinery than other merabers of the fauna.

Faraiiy CANIDAE

Osteoborus validus (Johnston)

A shattered right raaxillary, coliect.id by Mr. Robert Morrov;, is the only specimen which can definitely be attributed to tais 3_ecies (Flate

8). This extremely large species, described in detail on the basis of raaterial frora the Higgins locality (Johnston 1939), is restricted to the Early Hemphiilian localities of the Texas Panhandie. In addition to the maxillary fragraent, three preraolar fragraents (TTU-P-9494-9496) also appear to be referrable to the genus Osteoborus.

Faraily FELIDAE

Aithough generic deterraination is irapossible it appears that two phalanges belong to this faraiiy. One, a ieft second phaiange (TTU-P-

9497) is reraarkably close in size to that of Machaerodus, a character- istic felid of Hemphillian faunas of the Texas Panhandie, as illvistrated by Burt (1931). The other slightly smaller specimen (TTU-P-9498) may be a proximal phalange, but it is diseased over virtualiy its entire length. This is the only identified specimen in the coliection with obvious indications of paleopathological disease.

Order PROBOSCIDEA

The vast majority of the bones seen by the writer as they occurred 58 in the bone bed were derived from one group of proboscideans, the goraphotheres. Preservation, on first inspection, appears to be good, but the bones and teeth are actually quite soft. Most were irreparably daraaged by the heavy equipraent utilized by the quarry operators. Exca- vated speciraens indicate the genus Goraphotheriura as defined by Tobien

(1973), but field observations also indicate the presence of the genus

Rhynchotherium.

Family GOMPKOTHERIIDAE

Gomphotherium sp.

Tobien (1973) has recentiy placed most of the Pliocene gomphotheres back into the genus Gomphotherium because of their obvious sirailarities.

The following speciraens were identified as Gomphotheriura in line with this work.

Of the eight to ten good speciraens in both private and pubiic collections, only three can definitely be attributed to this genus. Mr.

Robert Morrow managed to excavate a neariy compiete mandible (Plate 9),

The first left molar and entire right dentition were sheared off by the heavy machinery and the ascending rami were iost as the specimen was initially uncovered. At the same time the tusks were cracked at the symphysis. Even with all this damage it remains one of the iargest compiete specimens collected from the quarry.

A sraaller right raraus (TTU-P-9499) was also recovered frora the deposits. This speciraen retains two raolar teeth. The tusk in this specimen is very short.

A crushed skull (TTU-P-9500) is probably also referrabie to this genus (Plate 10). Both tooth rows are intact, but the tusks have been o^

lost. The anterior teeth on both sides show extensive .sear while the

posterior teeth were only beginning to wear. The symphysis is preserved

and it appears to have been relativeiy long. The condyles on the back

of the skull are also preserved, but this portion of the skuli is badly

crushed.

Rhynchotherium sp.

In his discussion of the gomphotheres, Tobien (1975) claims to be

able to find no specimens which show enamei banding on tne iower tusks,

the central character of the genus Rhynchotherium. He therefore doubts

the validity of this genus. During the operation of the heavy machinery

however, notes on the occurrences of a number of iower jaws with enaraei

banded tusks were made. This indicates the presence of the genus

Rhynchotherium, and this taxa is considered to be a valid one.

In addition to the jaw material, large quantities of post cranial

elements also occurred in the deposit. In ali cases these elements

were disarticulated, but in sorae cases articulating elements did reraain

in close proxiraity. It was not possibie during this study to determine

to which of the two general individual eleraents beionged.

Order PERISSODACTYLA

While numerically less abundant than proboscidean fossils, members

of this order constituted the most readily identifiable portion of the

fauna. Although rhino specimens were among the most poorly preserved

of ali the material to be identified in the quarry, the diverse equid

fauna was both the best preserved and the most diagnostic material in

the collection. In large part the age designation of the fauna is based on the equid material. 0

Family EQUIDAE

Pliohippus sp.

A major portion of the equid raaterial recovered from the quarry undoubtedly belongs to this large singie toed horse. Unfortunately only upper and lower cheek teeth can definiteiy be identified because isolated pliohippine post cranial skeietal raateriai is difficult to discrirainate frora that of the other large horse in the fauna, Neohip- parion. The raost complete specimen of Pliohippus recovered thus far is a right lower tooth row in which the iabial portion has been cut off by the heavy equipment (TTU-P-9501). Two teeth are preserved virtuaily intact, except for an antero-posterior crack, while labiai halves are raissing in two others. Plate 11 shows a series of isoiated upper and lower cheek teeth (TTU-P-9502-9507).

Neohipparion sp.

A nuraber of isolated upper teeth and one isolated iower tooth collected by the writer can definitely be assigned to this genus.- Aii the upper cheek teeth have the characteristic isoiated lenticuiar proto- cone. Plate 12 shows a series of upper teeth. (TTU-P-9508-9511).

Mr. Robert Morrow is in possession of a coraplete right upper tooth row (P2-M3) of this genus (Plate 13). The specimen is interesting in that while it has an oval protocone of a kind that is comraon in N^. coloradense, it also shows extrerae coraplexities in the area of the pli-protoloph (Plate 14) which is common in the later more advanced species N. eurystyle from the Hemphill area (Matthew and Stirton 1950b).

The overall siraplicity of the fossettes in the isolated upper teeth

(Plate 12) again reserables the condition in the typical Clarendonian species N. coloradense (Webb 1969). With such a restricted saraple it 41

would be unwarranted and unwise to atterapt to identify the raaterial

down to species, but it is interesting to note that these speciraens

suggest a stratigraphic position between the typical Ciarendonian and

Heraphillian species.

Nannippus sp.

Occurring in the fauna alongside the two iarger horses mentioned

above is a very small horse. The few specimens of small but mature

equid skeletal materiai are referred to the genus Nannippus on the

basis of an isolated upper tooth (TTU-P-9512; Plate 15). Aithough it

is not possibie to determine the original crown height, the tooth appears

to have been hypsodont. At its present crown height(20.4 railiimeters

above the base) the protocone approaches but does not connect with the

protoselene (Plate 14). In addition the hypoconal groove is straight

and exhibits no tendency towards closure. These characteristics serve

to indicate that the specimen belongs to the Hemphillian genus Xannippus

rather than the Clarendonian genus Pseudhipparion in which the protocone

does connect with the protoselene and hypoconai groove forms an enciosed

lake (Webb 1969).

Faraily RHINOCEROTIDAE

Two speciraens referrable to this family have been identified in the collection. The first specimen, a broken tooth, was brought to the attention of the writer by the earth stripper operator. The second specimen (TTU-P-9513) is a portion of a mandible of another individuai

(Plate 16). Although severely damaged by the heavy machinery, this specimen preserves the tusk and a portion of the second preraoiar on the left side and a portion of the second preraolar, the entire third 42 preraolar, and a portion of the fourth preraoiar on the right side. The ramus is relatively slender, but the symphysis is extremeiy deep. The material is too fragmentary to identify to genus.

Order ARTIODACTYLA

To date only one raerabero f this order, a iarge caraei, has defi- nitely been recognized in the fauna. There are suggestions however that smaller artiodactyls also occur in the fauna. A few pieces of tooth enamel, which appear to come frora an antelope-iike aniraal, have been found. These fragments are too scanty to be reliable but the presence of an antilocaprid in the fauna would not be unusual.

Family CAMELIDAE

Megatylopus sp.

A partial left ramus (TTU-P-9514) which appears to belong to this genus was recovered in one of the quarry walls at the ievel of the bone bed. This specimen preserves the second and third molars intact with a broken portion of the first molar (Plate 17). Mr. Robert Morrow has also recovered post cranial raaterial frora a large caraei (Piate 18).

Faunal Interpretations

Faunal identification provides two useful forras of data. Firstly, the ecology of the area can be described with some accuracy. Secondly, the association of particular forms in the Janes quarry makes it possibie to establish the faunal age of the deposit. Later these faunai data will be combined with the sediraentological and taphonomic data to permit a paleoenvironmental reconstruction of the area.

The fauna which has been described above indicates that the central 45 portion of the Llano Estacado was populated by large herds of various kinds of herbivores, and that these herds were stalked by a number of large camivores. The fauna may sampie three biotic communities with daiiy ranges that overlapped at the river channei, the primary source of water in the local area.

Shotwell (1961) has postulated that the evolution of open grass- lands in the Miocene may have given irapetus to the replacement of three- toed horses by one-toed forras. It is his theory that the two extra toes may have acted as lateral stabiiizers in forms that had to make rapid directional changes in a savannah woodland environraent. Deveiopment of corapletely open environraents resulted in loss of selection for this trait and thus may have accelerated the natural trend in equids toward digital reduction. Occurrence of both types of horses in the Janes

Quarry fauna raay indicate the presence of both open savannah and woodiand savannah environraents.

There can be no doubt however, that there was a weii deveioped riparion woodland comraunity in the area. The goraphotheres and the caraels are both browsers that require large amounts of shrubs and small trees for food (Douglas-Hamilton 1975). CHAPTER V

BIOSTRATIGRAPHY AND AGE OF THE JANES QUARRY

Biostratigraphy

The fauna from the Janes Quarry inciudes Pliohippus, Neohipparion,

Machaerodus, and Gomphotherium along with rhinos and cameis. These are

sufficient indications to place the fauna somewhere within the Claren-

donian or Hemphillian Land Mamraal Ages as defined by the Wood Committee

(Wood and others 1941). The materiai occurs in the iower Bridweil which

Evans (1949), although he did not use the term, obviously equated with

the Hemphillian on the basis of the occurrence of the small pliohippine,

Astrohippus.

Astrohippus does not occur in the Janes Quarry. It is a late

Hemphillian form in the type areas to the North. In fact the large

horses, Neohipparion and Pliohippus in the Janes Quarry fauna are very

similar to the Clarendonian horses found to the north (Schuitz 1977) .

This makes the designation of the faunal age somewhat difficult.

On the basis of the occurrence of the sraall horse Nannippus, and

in line with Webb (1969) it is probable that the Janes Quarry fauna is

very early Heraphillian rather than late Clarendonian. This agrees with

the placement of the extremely similar Higgins fauna and it raakes it

possible to estimate the age of the fauna.

Age

Berggren and Van Couvering (1973) present a list of dates on the

Clarendonian and Hemphillian localities of North America which are

associated with datable volcanics. They indicate that the earliest

Hemphillian occurs about 10 million years ago. They also show that 44 45 this time period corresponds to the Middie Miocene of the Mediterranean area.

On the basis of these dates the Lower Bridweii and the Early

Hemphillian fauna it contains as exposed at the Janes Quarry dates from about 10 to 8 million years ago. This also dates the new episode of raountain building in New Mexico that produced the streara rejuvenation sequence seen in the Ogallala of West Texas. CHAPTER VI

TAPHONOMY OF THE JÆNES QUARRY

Taphonoraic Observations and Interpretations

In the process of doing the fieldwork at the Janes Gravei Ouarr>-,

a nuraber of interesting taphonoraic observations were made. These wiil

be presented in terms of the sequential factors developed by Ciark and

Kietzke (1967). Tnterpretation of these data aiong with other facts

conceming the paleontology and geology of the area will be used iater

to develop a paieoenvironmental reconstruction of the area at the time

the animals were alive.

Biotic Factors

The aniraals found and identified indicate three basic coramunities,

The large one-toed horse, Pliohippus, represents an open plains herd

aniraal while the three-toed horses raay have preferred an open savannah

woodland environraent (Shotwell 1961). The mastodonts and caraeis repre-

sent riparion woodland browsers living in a vegetated strip aiong the

waterway. The horses were herd animals. The mastodonts probabiy

traveled in ioosely aggregated extended family groups as their descen-

dents in Africa do today (Douglas-Haraiiton 1975).

Recent work on elephant ethology(Douglas-Hamilton 19~5) indicates

that while these animals norraally travel only in extended family groups

of 8 to 15 raembers, they tend to congregate in large herds early in the

Spring when fresh shoots are avaiiable. Tnis is the tirae of raating

for these aniraals. It raight also be the tirae for Spring floods which could trap large groups of animals in a streambed. 46 4'

Thanatic Factors

All the animals found in the assemblage have modem counterparts that are especially susceptible to miring. They are aiso susceptibie to being caught in flash floods. These are forms of catastrophic death, and one would expect a cross section of the population with iarge numbers of healthy, raature adults in such a death asserablage (Voorhies 1969).

This is exactly what was found at the quarry. Although juveniie eleraents such as bones with unfused epiphyses and unerupted teeth occur along with paleopathologicai bones and heaviiy worn teeth frora oider individuals, the preponderance of raaterial refiects mature aduits. The camivores which preyed on the large herbivores are aiso found in the asserablage, but there is no evidence of death by predation. Rather the camivores seera to have been caught by the sarae event that entrapped the larger animals. Because it is rather doubtful that such a large number of animals would all be caught by rairing, it is more iikely that they were caught by some sort of flash flood.

Perhaps raore iraportant in the consideration of the thanatic factor is the sheer size of the death asserablage. The quarry extends over an area in excess of 31 acres. The bone bed is exposed in ali visibie quarry walls and tracing of these beds indicates that they are continuous with those portions of the bone bed excavated during the project. There are proboscidean remains in all exposures and an araateur coliector who works at the quarry raaintains that these proboscidean remains occurred throughout the entire deposit. He also maintains that the density of material has remained constant throughout.

If one assumes that density of material has been constant through- out the deposit, then, on the basis of observations made during the 48

intensive excavations, one raust a ssume a minimura nuraber of at least

507 gomphotheres. This number is based on the distribution of individual

tooth rows, assuming that each aniraal possessed 4 such tooth rows (two

upper and two lower). This esitiraate is important to the discussion of

biotic factors.

Perthotaxic Factors

Because so raany of the bones are 'fresh' and unbroken, there does

not appear to have been any significant exposure to surface weathering

before entombraent. There is also no evidence of scavenging prior to

burial. Behrensraeyer (1975) has docuraented the coraplete destruction of

carcasses due to scavenging in less that 2 days while exposure of iess

than 1 season in Africa leads to coraplete destruction by weathering.

Burial, therefore, raust have been siraultaneous with the death of the

animals.

Taphic Factors

The bones in the bone bed are disarticulated but members cf aii the

Voorhies groups are present. This indicates that iittle or no sorting

took place prior to burial. The material did not become sorted because

it was incorporated into the deposits as complete carcasses. The fact

that these animals are not found in an articulated condition indicates

at least one episode of minor reworking of the sediraent perhaps by smail

channelet moveraent in the raain channel.

Voorhies (1969) mentioned that small elements had a tendency to orient transvers to current direction when caught in the troughs between ripple crests. This has been confirmed in this study. The large size of the ripples in the Janes Gravel Quarry, however, has permitted larger bones to become transversely oriented than Voorhies described. 49

Anataxic Factors

Diagenetic changes in the elements after entombraent are somewhat

difficulat to docuraent. Caicium carbonate has nucieated around some

bones to form dense hard sheathes which preserve them. This is especially

true near the clay drape. In addition to this chemical activity there

is one case of physicai damage also. In the area of the black graveis

(Figure ) some crushing is evidenced and is probably due to compaction

of the deposit.

Sullegic Factors

Because the material coilected and noted represents an extremeiy

small percentage of the total assemblage, the faunal list must be

considered incoraplete. Aithough further work raay expand the faunal list,

the writer would not expect the character of the fauna to change. The

depth of the fauna (22 feet beiow the surface of the ground) has insured

that there has been no significant previous coliecting frora this iocality.

Trephic Factors

Reconstruction of the paleoenvironraent of the area does not require

great accuracy in faunai identification. It is just as usefui to

recognize the fact that a speciraen belons to a single-toed horse as it

is to know which species of Pliohippus it represents. This mitigates raany of the potential curatorial errors.

Evaluation of Taphonoraic Procedures

In one sense it is disheartening to consider a fossil assembiage in terms of the seven factors defined by Clark and Kietzke (1967), because it is obvious that accurate corrections for the effects of these factors are impossible. It is equally distressing to note that the 50 procedures developed to cope with such problems as transport are too

simplistic and mechanical. Even with these probiems, however, the

taphonomic theory that a fossil's relationship to its sedimentary deposit is an important source of data, has been found to be an

extremely productive approach to paleoenvironmentai reconstruction.

It has been stated in earlier iiterature that taphonomy is a

distinct subdiscipline which is separate from paleoecoiogy (Voorhies

1969, Behrensmeyer 1975). These authors aiso expressed the opinion

that paleoecological reconstructions are not possibie without a

taphonoraic reconstruction to correct sarapie biases. This is impossibie

as Clark and Kietzke's (1967) first factor, the biotic, is essentialiy

a paleoecological reconstruction in itself. This is ciearly a case of

circular reasoning and should be recognized as such.

On a more practical level the use of Voorhies' groups in the

determination of the hydrodynamic history of an assembiage raay aiso be

open to question. The use of these groups assuraes that coraplete, but

disarticulated skeletons were introduced into the streara at a distance

sufficiently far upstreara to ailow sorting to occur. These conditions

are rarely raet in natural systeras.

Behrensraeyer (1975) has documented the rapidity with which animal

carcasses are destroyed on the open plain in Africa. It is her contention

that only animals which die within a stream course ever become incor- porated within its deposits. Therefore few if any disarticuiated bones

are ever introduced into the streambed. This idea impiies that

Shotwell (1955) was probably wrong in his assumption that fragmentary

skeletons of distant biotic communities might be found in an assemblage.

It is predominately the entire carcasses already within the streambed 51 that are subjected to sorting. If these carcasses are subjected to weathering, scavenging or predation the skeletai universe will not be identical to that of Voorhies' experiments and therefore the Voorhies' groups raay be altered.

Altematively, carcasses may be introduced into a sediraent body as intact entities. In this case the bones wili be undaraaged, but the skeletons will be found in articulated position. With this in mind it is probable that sediraentarty deposits which preserve undaraaged, disarticulated bones document a reworking of the sediment body, and thus a two fold hydrodynamic history of the fauna. This is the case at the

Janes Gravel Quarry.

The problems listed above arise from an overzealous atterapt to demonstrate the validity of taphonomy as a separate subdiscipiine.

There is no way to completely separate it frora paleoecoiogy, but an awareness of the sarapling stages which a fauna has encountered is necessary if one wishes to utilize the paleontological record for more than a paleobiological exercise. It is also one of the most efficient ways by which one can study the paleoenvironment of a region. CHAPTER VII

RECONSTRUCTION OF PALEOEN'VIRONMENT

AND CONDITIONS OF INTExRMENT

Correlation of the interpretations of the sedimentological, paleontological and taphonomic data from the Janes Quarry and surrounding

areas makes it possible to generate a paleoenvironmental reconstruction of the area. The following model is testable from the diverse fields of

soil science, geology, botany and paleontology.

Approxiraately 11 to 10 million years ago, during the Miocene Epoch,

aggradation in the area of the Llano Estacado had teraporarily ceased.

A paleo-mollisol, a semiarid land soil which characteristically develops

an indurated petrocalcic horizon, had formed in the fine grained sands

at the top of the Couch Forraation. At this tirae stream rejuvination

of the generally southeasterly flowing river occurred and coarse sand

and gravel sections, often incorporating boulders, formed in the base of the Bridwell Formation.

There is no angular unconforraity between the sediments of the two

formations, and the entrenched streara channel appears to have been stable. In addition the soil types reraained constant. These facts suggest that climate was relatively stable, and that the stream rejuvination cannot be accounted for either by a lowering of sea level or tectonic deforraation of the local area. It is raore probable that this rejuvenation occurred with a new episode of uplift in the raountains of New Mexico.

At the timc of streara rejuvenation, the semiarid climate of the

Llano Estacado area supported open savannah and savannah vsfoodland biotic 52 oo zones in the interfluves with a riparion woodiand community occurring along the river. These environments were the habitat of a diverse fauna of large herbivores and carnivores that included three kinds of horses, large camels, rhinos, gomphothere proboscideans, and large canids and felids. The appearance of this area at this tirae was very iike the

Serengeti Plain of Africa today.

At sorae tirae of the year, possibly in the spring, iarge nurabers of these aniraals were gathered near the river, the raajor source of water in the area. A catastrophic event, perhaps a flash fiood, occurred and buried a large number of animals very rapidly. Later minor channeiet reworking destroyed any evidence of articulation in the skeletai material. The extreme velocity of the flood waters or the competency of the stream during reworking of the sediraent reraoved ail evidences of sraall animals that probably iived in the area.

Sediment aggradation continued and the fauna was buried quite deeply. At some later tirae the headward erosion of the Pecos and

Canadian Rivers isolated the Llano Estacado frora its water and sediraent sources in New Mexico. Today a modern mollisoi is deveioped on top of the coarse grained deposits of the lower Bridweli which forms a resistant bench on the side of Yellowhouse Draw. CHAPTER VIII

CONCLUSIONS

The study of the faunal material exposed in the Janes Quarry has produced a series of specific conciusions conceming their origin and initiai depositional history. These are as foiiows;

Geoiogy

1. The Janes Quarry occurs in the Lower Bridweii Formation.

2. The Lower Bridweil Formation represents a braided stream

environment.

3. Tlie braided streara deposits docuraent a stream rejuvenation

sequence.

4. The streara rejuvenation sequence occurred approxiraately 10

million years ago and was due to a new episode of mountain

uplift.

5. The quartzite gravels at the ievel of the bone bed document

the breach of the metamorphosed core of the Sangre de Cristo

Mountains of New Mexico.

6. The continuous developraent of soils with petrocaicic horizons

throughout exposed sections at the Janes Quarry indicates

that the cliraate was semiarid throughout this time period.

Paleontology

7. The fauna at the Janes Quarry belongs to the Early Hemphiilian

r Land Mammal Age.

8. The Early Hemphillian belongs in the Miocene Epoch.

9. The fauna documents both savannah and riparion woodland

biotic communities. 54 OD

Taphonomy

10. The death assemblage at the Janes Quarry represents a

catastrophic event.

11. Faunal asserablages, like that of the Janes Quarry, which

preserve aii of the skeietai eiements in an undamaged,

disarticulated condition, document at ieast 2 depositionai

events, initial deposition with the death event and subsequent

reworking.

12. At least 500 gomphotheres were included in the Janes Quarry

death assemblage.

13. The proboscidean population density indicates that the deaths

took place in early spring. REFERENCES CITED

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62 63 Plate 1: Map of the Janes Gravel Quarry Area. Adapted from the Caprock, Texas 7.5 minute U.S.G.S Quadrangie Sheet Legend

outiine of modern quarry

outline of older portions of the quarry

C--C' main east west quarry wall

D--D' northem extension of quarry wall 64

^ Mf *• /5« 1

It '

V • U \ n •i'«gm«h^V>'. K»".^ '••-^'\Ql 65 Plate 2:View showing modern Quarry wall

Plate 3: Stratigraphic Section 1

l i 66 6' Plate 4: Stratigraphic Section 2

Plate 5: Stratigraphic Section 3 68 69 \^

Plate 6: Clay drapes on braid bar islands

, Plate 7: Close up of sand filled dessication cracks in the clay l drapes of the braid bar island 4 70

^T"^ y-..^ 71 Plate 8: Overview of right raaxillary of Osteoborus validus from the collection of Mr. Robert Morrow

Plate 9: Goraphotheriura raandible from the collection of Mr. 't Robert Morrow ^ 72

i4.i.i.iJ.hl,i.l.i,i,i,l,i,i,i,l,hi,i,l,i,i,i,Liil,i 1,1,1, I • 'I ll'l'l-'.'.' ,.,.••!. .1 73 Plate 10: Crushed skuli of Gomphotherium (TTU-P-9300)

t J< Plate 11: Upper and lower cheek teeth of Pliohippus sp (TTU-P-9502-9507) 74 75 •^-- «* #-•• \^

Plate 12: Upper cheek teeth of Neohipparion sp. (TTU-P-9508-9511)

C Plate 13: Right upper cheek teeth of Neohipparion sp. from '^ the collection of Mr. Robert Morrow 76

\^

Plate 14: Diagram of upper horse tooth

Abbreviations

p parastyle m mesostyle ppfl pli postfossette- pli protoloph ppfll pli postfossette II r rib me metastyle pof postfossette ph pli hypoloph hyf hypostylar fossette hy hypostyle hg hypoconal groove h hypocone pc pli caballin pro protocone c commissure of protocone ps protoselene prf prefossette pprc pli protoconule pprf pli prefossette 78

Ppf I 79 Piate 15: Isolated upper tooth of Nannippus sp. (TTU-P-9512)

Plate 16: Mandibular fragraent of an unidentified rhinocerotid (TTU-P-9513) 80

Piate 17: Partial left ramus of Megatyiopus sp. (TTU-P-9514)

4

Plate 18: Canon bone from a large camel cf. Megatylopus sp from the collection of Mr. Robert Morrow 82