The Osteology and Myology of the Head and Neck Region of Callisaurus, Cophosaurus, Holbrookia, and Uma, the "Sand Lizards"

Home , Earless lizard, Holbrookia, Holbrookia elegans, Holbrookia lacerata, Holbrookia maculata, Holbrookia propinqua

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Theses and Dissertations

1976-12-01

The osteology and myology of the head and neck region of Callisaurus, Cophosaurus, Holbrookia, and Uma, the "sand lizards"

Douglas Charles Cox Brigham Young University - Provo

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BYU ScholarsArchive Citation Cox, Douglas Charles, "The osteology and myology of the head and neck region of Callisaurus, Cophosaurus, Holbrookia, and Uma, the "sand lizards"" (1976). Theses and Dissertations. 7665. https://scholarsarchive.byu.edu/etd/7665

This Dissertation is brought to you for free and open access by BYU ScholarsArchive. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. THE OSTEOLOGYAND MYOLOGY OF THE HEADAND NECKREGION OF

CALLISAURUS,COPHOSAURUS, HOLBROOKIA, AND __UMA, THE "SAf-11)LIZARDS"

A Dissertation

Presented to the

Department of Zoology

Brigham Young University

In Partial Fulfillment

of the Requirements for the Degree

Doctor of Philosophy

Douglas Charles Cox

December 1976 This dissertation, by Douglas Charles Cox, is accepted in its present form by the Department of Zoology of Brigham Young University as satisfying the dissertation requirement for the degree of Doctor of Philosophy.

ii ACKNOWLEDGMENTS

I express my deepest gratitude to Drs. Wilmer W. Tanner,

Herbert H. Frost, Joseph R. Murphy, Glen Moore, Clive D. Jorgensen, and H. Duane Smith for the advice they gave during the preparation of this dissertation. As members of the Committee, they read the manuscript and provided helpful suggestions.

I also acknowledge the special assistance rendered by Dr.

Stephen L. Wood who advised me in the taxonomic considerations of this study. I was aided in the statistical analysis by Drs. H. Gill

Hilton and Alvin C. Rencher. Valuable assistance in preliminary statistical computations and computer set-up was given by Wendell

Kerr.

For the loan of specimens used in this study, thanks are extended to Dr. Wilmer W. Tanner of the Brigham Young University

Life Sciences Museum and to the California Academy of Sciences,

Department of Herpetology. Bryce C. Brown, Director of Strecker

Museum, Baylor University, also provided a gift of specimens for dissection.

Sincere thanks go to the Life Sciences Museum for materials and facilities. The Department of Zoology supplied critical support, supplies and equipment. My final acknowledgments and deepest gratitude are extended to my wife and Dr. Wilmer W. Tanner. As my major professor, Dr. Tanner

iii iv has extended himself completely and continuously. He has encouraged me during periods of discouragement, stimulated my imagination, challenged me in every way, and patiently helped me through many difficulties. My wife, Anne Bischoff Cox, has been a supporting influence, giving me suggestions, encouragement, and patiently enduring the difficulties encountered during the course of this study. She advised me in the preliminary writing stages and typed the rough drafts. Her love and help is gratefully acknowledged. TABLE OF CONTENTS

Page

ACKNOWLEDG1·1ENTS iii

LIST OF FIGliRES vi

LIST OF PLATES , · .viii

LIST OF TABLES ix

INTRODUCTION AND REVIEW OF LITERA.TURE 1

:-1ATERIALSAf,;1) METHODS 7

OSTEOLOGY 9

STATISTICAL ANALYSIS • 25

HYOLOGY 66

DISCUSSION • , . 92

L ITERATU3.ECITED • 109

V LIST OF FIGURES

Figure Page

1. Plot of Ratios Presented in Table 1 ...... 42 2. Plot of Ratios Presented in Table 2 . . . . 43 3. Plot of Ratios Presented in Table 3 ...... 44 4. Plot of Ratios Presented in Table 4 45 5. Plot of Ratios Presented in Table 5 . . . . 46 6. Plot of Ratios Presented in Table 6 . . . . . 47 7. Plot of Ratios Presented in Table 7 . . . . . 48 8. Plot of Ratios Presented in Table 8 . . . . 49 9. Plot of Ratios Presented in Table 9 ...... so 10. Plot of Ratios Presented in Table 10 . . . . 51 11. Plot of Ratios Presented in Table 11 ...... 52 12. Plot of Ratios Presented in Table 12 53 13. Plot of Ratios Presented in Table 13 . . . . 54 14. Plot of Ratios Presented in Table 14 ...... 55 15. Plot of Ratios Presented in Table 15 . . . . 56 16. Plot of Ratios Presented in Table 16 57 17. Plot of Ratios Presented in Table 17 . . . . 58 18. Plot of Ratios Presented in Table 18 . . . . 59 19. Plot of Ratios Presented in Table 19 . . . . 60

20. Plot of Ratios Presented in Table 20 61

21. Plot of Ratios Presented in Table 21 62

vi vii

Figure Page

22. Plot of Ratios Presented in Table 22 . . . . 63 23. Example of Discriminant Score Plot from Test 113 64

24. Example of Discriminant Score Plot from Test ff4 65 LIST OF PLATES

Plate Page 1. Dorsal View of Skull ...... 30 2. Ventral View of Skull . . 32 3. Lateral View of Skull ...... 34 4. Lateral View of Mandible . 36 5. Medial View of Mandible 38 6. Ventral View of Hyoid . . 40 7. Lateral View of Head and Neck Musculature; Superficial Depth . . • . • . . • ...... 74 8. Lateral View of Heah and Neck Musculature; First Depth. 76

9. Lateral View of Head and Neck Musculature; Second Depth. 78

10. Lateral View of Head and Neck Musculature; Third Depth. 80

11. Ventral View of Head and Throat Musculature; Superficial ~nd First Depth .•..••.•.•.••••• 82

12. Ventral View of Head and Throat Musculature; Second and Third Depth •••••••.•••••.•• 84

13. Ventral View of Head and Throat Musculature; Fourth and Fifth Depth • . • • ..•••••.•••••.• 86

14. Dorsal View of Head and Neck Musculature; Superficial and First Depth • • . • • • • • • • • . • • • 88

15. Dorsal View of Head and Neck Musculature; Second and Third Depth • . • . . • . • • • . • • • 90

16. Phylogeny of the Sand Lizards According to Axtell (1958) 105

17. Proposed Phylogeny of the Sand Lizards .• 107

viii LIST OF TABLES

Table Page

1, Ratio of the Skull Length Divided by the Maxillary Length. 42

2. Ratio of the Skull Length Divided by the Squamosal Width •. 43

3. Ratio of the Skull Length Divided by the Quadrate Length •• 44

4. Ratio of the Skull Length Divided by the Mandible Length •. 45

5. Ratio of the Skull Length Divided by the Mandible Width •. 46

6. Ratio of the Skull Length Divided by the Hyoid Length. 47

7. Ratio of the Maxillary Length Divided by the Jugal Length. 48

8. Ratio of the Maxillary Length Divided by the Quadrate Length " . . . . , ...... 49

9. Ratio of the Maxillary Length Divided by the Hyoid Length. 50

10. Ratio of the Jugal Length Divided by the Squamosal Width 51

11. Ratio of the Jugal Length Divided by the Quadrate Length 52

12. Ratio of the Jugal Length Divided by the Mandible Length 53

13. Ratio of the Squamosal Length Divided by the Squamosal Width 54

14. Ratio of the Squamosal Width Divided by the Quadrate Length 55

15. Ratio of the Squamosal Width Divided by the Mandible Length 56

16. Ratio of the Squamosal Width Divided by the Hyoid Length 57

17. Ratio of the Quadrate Length Divided by the Quadrate Width 58

18. Ratio of the Quadrate Length Divided by the Mandible Length 59

19. Ratio of the Quadrate Length Divided by the Hyoid Length 60

20. Ratio of the Mandible Length Divided by the Mandible Width 61

21. Ratio of the Mandible Length Divided by the Hyoid Length 62

22, Ratio of the Hyoid Length Divided by the Jugal Length .•• 63

ix INTRODUCTIONAND REVIEW OF LITERATURE

Blainville (1835) wrote the first description of a sand lizard and named it Callisaurus draconoides. Since his time various authors have published articles concerning sand lizards. Girard (1851) described Holbrookia maculata, Trochel (1852) described Cophosaurus texanus, and that same year Baird and Girard synonymized Cophosaurus w;i.th Holbrookia providing the name Holbrookia te:xana·, which has stood for over 100 years. Subsequently, Baird (1858) described Uma notata.

By 1858 all genera represented in the samd lizard group had been described. From this point only new species and subspecies were added by various authors as follows: Bocourt (1874) Holbrookia elegans, Cope (1880, 1883, 1894, 1895, 1896, 1900) Holbrookia lacerata, Holbrookia maculata flavilenta, Uma scoparia, Uma inornata,

Uma rufopunctata Callisaurus crinitus, Callisaurus rhodostictus, ~ .

Holbrookia maculata maculata, Callisaurus draconoides ventralis,

Callisaurus ventralis gabbii, Stejneger (1890) Holbrookia maculata approximans, J!olbrookia maculata lacerata, Richardson (1915) Calli- saurus ventralis myurus, Dickerson (1919) Callisaurus carmenensis,

Schmidt (1921, 1922) Holbrookia maculata campi, Holbrookia pulchra,

Holbrookia dickersonae, Callisaurus ventralis inusitatus, Schmidt and

Bogert (1947) ~ exsul, Barbour (1921) Holbrookia thermophilia,

Harper (l932) Holbrookia propinqua stonei, Smith (1935, 1943, 1946)

Holbrookia elegans thermophila, Holbrookia elegans elegans, Holbrookia bunkeri, Holbrookia maculata ruthveni, Holbrookia maculata dickersonae,

1 2

Holbrookia maculata pulchra, Holbrookia maculata thermophila, Linsdale

(1940) Callisaurus draconoides myurus, Callisaurus draconoides gabbii,

Heifetz (1941) ~ notata nota_ta, Bogert and Dorsom (1942) Callisaurus

draconoides. . brevipes,. I • . Smith and Burger (1950) Holbrookia propinqua

PFopingua, Ho~brookia prop;i.nqua J?iperata, '.Peters (1951) HolbroL 1 kia

texana texana, Holbrookia texana scitula, Axtell (1956) Holbrookia

lacer a ta lacer a ta_, Ho_lBrooki~ lacerata subcaudalis, Holbrookia maculata

p_ers:eicua, Smith and Cochran (1956) Callisaurus draconoides rhodo-

stictus, Williams, et al (1959) Uma paraphygus.

Some summaries, reviews, check lists, and comparative studies

have also been written. Cope (1896) synonymized Uma and Callisaurus

in a short paper discussing the genus Callisaurus. He recognized

. Uma again in his large work on the crocodilians, lizards and snakes

of North America (1900). In this work Cope recognized one species and

three subspecies of Callisaurus.

Smith (1946), in his "Handbook of Lizards,'' recognized in

Callisaurus one species and ten subspecies, and stated (p. 145):

"The whole group of Callisaurus of western United States is in need

of revision. The subspecies are not adequately characterized, nor

are their ranges well worked out. There is very little information

on the life history," Although we now know much more about Callisaurus

it is still in need of a comprehensive review, and it remains a

monotypic genus. A careful.revision for Callisaurus has as yet not

been attempted.

The genus Holbrookia has had two revisions. Schmidt (1922)

made the first and the second was by Axtell (1958). Schmidt (p. 709)

stated: ''The taxonomy of the North American lizards of the genus 3

Holbrookia Girard offers one of the most interesting and difficult problems in North American herpetology."

He recognized:

1. Holbrookia texana (Troschel) 2. Holbrookia propinqua Baird and Girard 3. Holbrookia elegans Bocurt 4. Holbrookia pulchra Schmidt 5. Holbrookia lacerata Cope 6. Holbrookia maculata maculata Girard 7. Holbrookia maculata flavilenta Cope 8. Holbrookia maculata campi Schmidt 9. Holbrookia maculata approximans Baird 10. Holbrookia dickersonae Schmidt

Schmidt (1922? 712) also explained: "Holbrookia is obviously directly related to Callisaurus, from which it differs only in the concealed tympanum and with which it agrees in general features of color pattern and scutellation."

Smith (1946: 119) stated:

"It appears very doubtful that a practical, concrete means of characterizing this race (Holbrookia maculata) and its relatives exists, yet until such a means is found there will remain indefinitely a problem in defining the ranges of the several subspecies, or in defending their actual validity. Accordingly the genus, particularly the rnaculata group, merits a careful study perhaps more than any other ~P ;he unite

1. Holbrookia lacerata lacerata 2. Holbrookia lacerata subcaudalis 3. Holbrookia propinqua propinqua 4. Holbrookia propinqua piperata. 5. Holbrookia mactilata maculata 6. Holbrookia maculata perspicua 7. Holbrookia maculata flavilenta 4

8. Holbrookia maculata campi 9. Holbrookia maculata ruthveni 10. Holbrookia maculata bunkeri 11. Holbrookia maculata marshi 12. Holbrookia maculata approximans 13. Holbrookia maculata alta 14. Holbrookia maculata thermophila 15. Holbrookia maculata elegans

Uma has been reviewed by Heifetz (1941), Norris (1958), and

Mayhew (1964b). Heifetz recognized Uma notata notata, Uma notata cowlesi, Utna inornata, and Uma scoparia. He also discussed taxonomic confusion that exists because of erroneous type localities in this genus.

Schmidt (1953) in his check list only recognized one species

(notata) with three subspecies (notata, inornata, and scoparia).

Norris (1958) recognized Uma notata notata, Uma notata rufopunctata, Uma notata inornata, Uma scoparia, and Uma exsul. He discussed the evolution of Uma and its relationship to other sand lizards.

The conflict relative classification of the notata-scoparia group was discussed by Mayhew (1964b). He recognized inornata, notata, and scoparia all as full species on the basis of temperature tolerance and reproductive data.

Cophosaurus texanus (Iiolbrookia texana) was reviewed by Peters

(1951). He described two subspecies, outlined the history of the

species, but mentions little concerning relationships with other sand lizards.

Clarke (1965) revived Cophosaurus texanus on the basis of behavioral data collected in a large comparative study of the sand lizard group. 5

Ecological and behavioral studies concerning sand lizards have also been published by Burt (1931a, 1931b), Stebbins (1944,

1954, 1966), Ramsey (1948, 1949), Cagle (1950), Williams and Smith

(1958), Axtell (1960), Lannom (1962), Carpenter (1963, 1967), Clarke

(1965), Mayhew (1964a, b, 1966), Pianka and Parker (1972), Tanner

and Krogh (1975), and Judd (1974, 1975).

The anatomy of sand lizards has never been thoroughly

studied. Earle, in a series of articles (1961a, b, c, 1962) described

the anatomy of the middle ear of sand lizards and compared them.

Stebbins (1943, 1944) described the nasal structures and some aspects

of the ecology of Uma, then (1948) described the nasal structures of

lizards in general and included sand lizards. Axtell (1958)

described the osteology of Holbrookia and stated that it is essen-

tially the same as found in all sand lizards. Ethridge (1964)

studied the skeletal morphology of sceloporine lizards which in-

cludes sand lizards, and compared their relationships. Savage (1958)

studied Urosaurus and Uta and made remarks concerning related genera

which included sand lizards. A few references to sand lizards were

made by Larsen and Tanner (1974) while studying Sceloporus~ and

Presch (1969) also refers to them in his study of the "Evolutionary

Osteology and Relationships of the Lizard Genus_ Phrynosoma (Family

Igua~idae)\'• Guttman (1970) conducted an electrophoretic study of

the hemoglobins of sand lizards and fo~nd that all genera possessed

the same major and minor protein components.

Only portions of the osteology have been adequately treated

and the myology is essentially untouched. There is a great need, for

a comparative study of the osteology and myology of sand lizards. 6

The objectiyes of the study are to: (_1) descr;ibe the skull osteology and branchion1er;i.c myology of sand 1:tzards; (2) identify osteological and niyological characteristics that distinguish the sand lizard groups; and (3) determine more accurately the relationships between groups, No attempt will be made to deal with the species and subspectes except as they relate to the generic phylogeny. MATERIALSAND METHODS

Specimens used were obtained from the Brigham Young University

Life Sciences Museum (BYU), the California Academy of Sciences (CAS), and Strecker Museum at Baylor University. At least four specimens

from each of the four genera, Callisaurus, Cophosaurus, Holbrookia,

and Uma, were used for osteological examinations. The myology of

these sixteen specimens plus four more from each genus was also described. Refer to the following listing: Callisaurus draconoides

gabbi from N.T.S., Nye Co., Nevada: (BYU) 2943, 2967, 3079, 40037;

_f. ~- :inusatatus from Tiburon Island, Sonora, Mexico: (BYU) 30175,

30176, 30178; _g_.j!_. splendidus from Isla Angel de la Guardia, Gulf of

California, Mexico: (BYU) 41112; _g_.5!_. carmenesis from Baja Cali-

fornia del sur, Mex:i,co: (:BYU) 41095, 41231; Cophosaurus texanus

texanus from Chihuahua, Mexico: (BYU) 14339, 15712; f· .!_. scitula

from Sierra Co., New-11exico: (BYU) 30512, 30513, 30515; .f._• .!.·

scitula from ?ima Co., Arizona: (BYU) 34331, 34336; Holbrookia

lacerata from Giaraz Co., Texas: (CAS) 73979; H. maculata approximans

from Colonia Dublan, 11exico: (:BYU) 11370, 17099; R. maculata bunkeri

from Chihuahua, Xexico: (BYU) 15782, 15785, 15788, 15789; H.

propinqua propinqua from Padre Island, Cameron Co., Texas: (CAS)

1618.7; ~ notata inornata from Riverside Co., California: (BYU)

3263, 3266, (CAS). 22824, 22826; U. ~- cowlesi from Sonora, Mexico:

(BW) 30144, 30156; U. scopar~ from San Bernardino Co., California:

(BYU) 11389, (CAS) 42072.

7 8

Skeleta,1 )llaterial ~as prepar;-ed by- careful dissection, Bones were cleaned wtth forceps and dtssecting needles, soaked in Clorox bleach for several minutes to loosen soft tissues, after which further p:;i:.cking and clean;tng was done, Skulls were not allowed to dry but were preserved ;in 70% EtOH; this was to insure that cartilaginous

~keleta,1 elements could be examined. The statistical package for the Social, Sciences (_pPSS)_discri:m;tnant analysis was ut;i:.lized to aid

:tn the j.'

The stat:f;_stical. analysis w;Ul be described later.

Mylogical examinations consisted of careful dissection in which each muscle was separated and its origin and insertion determined. General morphology (shape, relative size and position) of

each muscle was also noted and muscle comparisons are based on both

origin-insertion and muscle morphology. Only the branchiomeric muscles associated with the hyoid arch and jaws are described. OSTEOLOGY

Skull

Bones of sand lizard skulls have been examined in detail and individual ele..t1ents were measured with a Golgau vernier Caliper and a five mill:imeter mini-tool. Forty-three r;ieasurements were taken and all possible ratios have been calculated. Comparisons were made on

the basis of the ratios, as well as shape and position of each bone in relation to other articulating bones. The lower jaw and hyoid have been studied in the same manner.

The skull of sc>.r.d lizards is streptostylic with a freely movable quadrate bone. In mature individuals of the four genera the braincase proper is not ossified in the 2.nterior portion but is membranous and provided with cartilagin:;us rods that add strength to

the membrane and protection to the brain. Eyes are large and only a

thin sheet of cartilage separates them medially; there is no ossifi-

cation of this cartilage seen even in mature individuals.

The Occipital Region

The occipital regio~ consists of thebr;:,.in:::ase (basisphzniod, basioccipital, exoc.::ipitals, supraoccipital, prootic, and the semicircular·canals), foramen magnum (which is enclosed by the basiocc:i.pital, exoccipital, and supraoccipital),. and occipital condyle, wh:i.cb is tripartate in all four genc~ra. Considerable fusion has occured in this area; therefol'.'e, accurate measurements of some of the individual bones is not possible

9 10 and height-vidth mcasu:i:-ements were. taken for the entire region. The width w~s the lateral extensions of the paraoccipital processes; and th_e height was from the floor of the brain case of the suture with the parietcJ:l bone,

Basiocd.pital

The has'5;occipltal (:Plate 2) forms the posterior floor of the brain case, It articulates anteriorly with the basisphe.noid and posteriolaterally with the exoccipitals. The basioccipital joins with the exocc~pitals to form the occipital condyle which forms the ventra.l post ion of the for amen magnum. The sphe:io-occipital tubercles a.re formed by a projection of the basioccipital and the basisphenoid, ·

the prootic also participates.

There are variations in the suture line between the basiocc.ipital and basisphenoid in all four genera. These variations range from distinct to partial fusion and from jagged to relatively smootll and straight,

Bas fspheno id

The basisphenoid (Plate 2) forms the anterior cranial floor and joins the bas;i,occipital posteriorly with a variable suture.

Anteriorly it sends out a thin, narrow process to join the para-

spheno;i.d which projects anteriodorsally between the palatines. An anteriolateral process. the basipterygoid process, connects with the pterygoid, and a posteriolateral process aids in the formation of the spheno-occ.ipital tubercles, The sella turcica is located on the dorsal surface, just posterior to the parasphenoid. 11

Th.e :Length uas considered to be f:i:-om the ectopterygoid p:i;-ocess to the sphenci-occipital tubercle, and the width was the distance between the cctopteryoid processes,

Exoccipital

The 1 2)_ exoccipital (Plate .. 1 occupies a pos;ition lateral to the foramen magnum, A major portion of the exoc.cipital is a lateral process called the paraoccipital process which joins the quadrate, squamosal, tabular, and the parietal wings.

The paraoccipital process is a fusion of the opisthotic with. the exoccipital. The exoccipital also fuses with the prootic bone which forms the lateral wall of the brain case and in conjunc- tion ·with the opisthotic bone forms the otic capsule for the inner ear.

The exoccipital is thin in sand lizards, a needle probe can b_e easily pushed through it to the underlying semicircular canals

·which are seen beneath the bone in a mature skull.

Sutures between the exoccip;ital and supraoccipital are fused and ;i:ndist:i.nct. Fus:i.on also takes place between the exoccipital and basiocc;i.p;i.tal,

Sui?raoc.c:i.pita_l The supraoccipital (Plate llforms the dorsal posterior postion of the brain case. It is fused to the exoccipital and loosely sutured to the parietal, often with fenestrae between these two bones even in -mature skulls. lt lies between the exoccipital and forms the dorsal portion of the foramen-magnum. 12

Pterygoid

The pterygoid (Plate 2) is located on the ventral aspect of the skull. It joins the palatines anteriorly and helps form the oral cavity roof. A process is sent out laterally from the pterygoid to join the ectopterygoid and a slender concave process is sent posteriorly joining the medial ventral portion of the quadrate, This quadrate process is thin and not completely ossified in many specimens examined.

The pterygoid is also connected to the basipterygoid process, and from the junction with this process a very slender bone, the epiperygoid, extends dorsally and is connected to the parietal by a tendon.

The length of the pterygoid was measured from the most anterior part of the suture with the palatine to the poster.tor extension of the quadrate process. The width was taken at the anterior point of union between the pterygoid and the basipterygoid process to the lateral process that joins the ectopterygoid.

Ee topterygo_id The ectopterygoid (Plate 2) is a short slender bone that lies between the pterygoid and maxilla. It forms the posterior border of the infraorbital fossa.

The length of the ectopterygoid was measured from its union with the pterygoid to its union with the maxilla. The width was taken from the length of the suture with the maxilla from the dorsal aspect. 13

Vomer

The anterior medial portion of the oral cavity roof is

formed by the vomers (Plate 2) They are bounded laterally and

posteriorly by the internal nares, Articulations are with the premaxilla anteriorly, maxilla laterally, and palatines posteriorly.

The length is the longitudinal extensions of the bone and width the lateral extension from the mid-point.

Palatine

The palatines (Plate 2) occupy a ventral position in the

skull forming a portion of the oral cavity roof. They connect

posteriorly with the pterygoids and anteriorly with the vomers.

There ;is a lateral connection with the maxilla, and the pair are

separated medially by a fossa containing the parasphenoid process,

They form the anterior border of the infraorbital fossa.

The length is the longitudinal extensions of the bone and

the width is measured from the medial edge to the lateral edge of the

bone at the widest point,

Premaxi.lla

The premaxilla (Plate 1, 2) ·1s a wedge-shaped bone extending

from the anterior tip of the snout posteriorly between the external

nares forming their anterior and part of their medial borders. It

becomes narrower as it continues posterior, and the anterior extensions

of the nasal bones are separated by the premaxilla. It articulates

w;i.th the maxilla anteriorlaterally, nasal posteriorlaterally, and ventrally with the vomer. On the dorsal surface at the anterior end the premaxilla has two conspicuous foramena and bears six to eight teeth ir: the ventral margin.

The length is measured from the tip of the snout to the posterior extension and the width is taken at the anterior end of the bone.

Maxilla

The maxilla (Plate _l, 2) occupies the lateral portion of the snout, and articulates medially with the prernaxilla anterior to the external nares, and articulates medially also with the nasal posterior to the nares. Posteriorly it joins the prefrontal, the jugal, and at its most posterior extension, the maxilla also joins the ectoptc-~·ygoid. From the ventral aspect the maxilla articulates with the vomer and the palatine bears all the teeth except those born by the premaxilla. Callisaurus has 18~24 maxillary teeth on one side, Cophosaurus from 19-21, Holbrookia from 17-20, and Uma from 18-19. Five to eight foramena are found on the lateral surface of the maxilla. The length was measured along the ventral tooth bearing surface, and the width was the vertical distance frora the tooth bearing.surface to the point where the maxilla joins the nasal and pref rontal.

Nasal

The nasal (:Plate 1) forms the posterior border and part of the medial border of the external nare. It articulates with the pre-

maxilla, maxilla, prefrontal 7 and frontal. The premaxilla pushes in 15 between the nasa.ls anteriorly, the frontal pushes in betweeci them posteriorly, but the nasals are not co~pletely separated medially.

The frontal does not reach the premaxilla.

The length was measured from the most anterior extension to the most posterior extension of the bone. The width was from the point where the maxilla, prefrontal, and nasal all meet, to the posterior extent of the premaxilla.

Prefrontal

The prefrontal (Plate 1, 3) is a C-shaped bone which occupies the anterior margin of the orbit. It articulates medially with the frontal and nasal, anteriorly with the nasal and maxilla, and laterally with the jugal. The prefrontal bears a conspicuous process that projects into the orbit. It is formed at the bones most lateral e.~tension. A small hook-like process may extend laterally from this process to meet the jugal in some individt.ials.

The length was measured from the prefrontal's most posterior extension along a straight line to its most lateral extension, The width was considered to be from the orbital pro~ess to the point where the maxilla, nasal, and prefron.tal come together.

Frontal

The frontal (Plate 1) forms part of the cranial roof and fills the area above and between the orbits. It articulates anteriorly with the nasals and prefrontals, posteriorly with the parietal, and laterally wi.th the postorbital bones. At the middle of the posterior margin there is a notch in the frontal bone that aic1s in the formation of the parietal foramen. 16

The length was considered to be the lateral extensions of

the bone along the parietal suture, and the width was from the parietal foramen to the anterior point between the nasal bones.

Jugal

The jugal (Plate 1, 2, 3) is a long, slender bone that forms

the ventral lateral margin of the orbit. The jug al articulates with

the prefrontal at the anterior end, the maxHla along the ventral

lateral side, and finally with the postorbital on the medial side.

The dorsal nargin of the temporal fossa is partially formed by the jugal bone. It touches the squamosal at its most posterior point and also articulates with the ectopterygoid ventromedially. This bone fails to reach the squamosal in one Uma individua.l (CAS 42076),

In Holbrookia and Cophosaurus the jugal comes between the squamosal

and the postorbital.

The length was measured between its longitudlnal extremeties

and the width was the vertical distance from the ventral border of

the orbit to the posterior point of the maxilla.

Parietal

The parietal (Plate 1) is a trapezoid-shaped bone with the

post~rior corners formed into long processes that extend posteriorly,

These processes will he discussed later as the parietal wings. The

parietal articulates with the frontal anteriorly and the lateral

points with the postorbital. There is a variable amount of poorly 17 ossified bone surrounding the parietal foramen which is located near the suture line bet·ween the parietal and the frontal. The parietal also received a tendon from the epipterygoid on its ventrolateral surface, and it forms a fenestrated suture with the supraoccipital posteriorly. The medial and posterior margins of the supratempral fossa are formed by the parietal with its wings. The anterior margin of the parietal hone is considered the length and the distance from the supraoccipital to the parietal foramen and its width.

Parietal Wing

The parietal wings (Plate 1, 3) are processes of bone that extend from the posteriolateral corner of the par.ietal posteriorly, latf>rally and curve ventrally to join the squamosa.l, paraoccipital process and quadrate. They form the posterio1~ border of the supratemporal fossa and also the post-temporal fossa roof. At their most posterior extremity these wings lie between the tabular and paraoccipital process and butt against the quadrate. The parietal wings bear the tabular on their lateral surface.

Postorbital

The postorbital (Plate 1, 2, 3) is a small bone forming

the posterior margin of the orbit and also the a1;terior margins of the supratemporal fossa. At a narrow point it joins medially with the

frontal and parietal and laterally in a broad articulation with the jugal and squamosal. The postorbital bone reaches into the dorsal margin of the temporal fossa between these two bones in one Uma

individual. 18

The length was considered to be the suture length with the jugal and the squamosal and the width was the distance from the frontal-parietal to the jugal-squamosal.

Squamosal

The squamosal (Plate 1, 2, 3) is a small bone in the posteriorlateral portion of the skull. It articulates with the postorbital, and jugal anteriorly, and with the tabular and quadrate posteriorly in a broad articulation.

Its length was considered to be from the posterior end to the anterior end, The width was the dorso-ventral distance at the posterior end.

Quadrate

The quadrate (Plate 3), is a C-shaped bone occupying the posterior and lateral corner of the skull. It articulates with the pterygoid ventrally and with the squamosal, tabular, parietal wing, and paraoccipital process dorsally, The most ventral extension of

the quadrate is the articulating surface for the mandible. The posteriolateral surface forms the auditory cup and a well developed,

laterally projecting flange marks the anterior border of this cup.

The tympanic membrane is attached to the lateral flange of the

quadrate and its posterior attachment is in the connective tissue beneath the anterior edge of the episternocleidomastoideus.

The columella extends laterally from the fenestra ovalis of

the otic capsule to articulate with the posterior surface of the quadrate. An extracolumella extends from this point to the tympanum. 19

The quadrate is proportionately large in Uma and Callisaurus.

In Cophosaurus it is smaller, and in Holbrookia it is the smallest.

The length was considered to be the distance from the suture with the squamosal to the articular condyles. The width was the widest point from the medial side of the bone to the lateral side.

Supratemporal fossa

The supratemporal fossa is an opening in the dorsal surface of the skull bounded by the parietal, squamosal, and postorbital.

It tends to be squarish in shape, but more narrow dorsally than ventrally.

Orbit

Each orbit is a large round opening in the lateral central area of the skull. It is bounded by the frontal medially, prefrontal anteriorly, jugal ventrally and laterally, and postorbital posteriorly.

A process of the prefrontal extends into the anterior portion of the orbit, The septum between the orbits is not ossified and in prepared skulls is usually lost.

Post Temporal fossa

The post temporal fossa is a small opening in the posterior

area of the skull, bounded by the parietal wings dorsally, the para-

occipital process posteriorly and ventrally, and the exoccipital and

supraoccipital medially and ventrally. 20

Temporal fossa

The temporal fossa is a large opening in the posteriolateral portion of the skull, bounded by the following bones: the dorsal arch, composed of the jugal and squamosal; the ventral border, composed of the pterygoid; and the ectopterygoid forms the anterior section. The maxillary bone enters the temporal fossa at the point where the ectopterygoid and jugal joins. The posterior border is formed by the quadrate.

Infraorbital fossa

The infraorbital fossa is an opening found on the ventral surface of the skull. It is bound laterally by the teeth-bearing maxilla, posteriorly by the ectopterygoid, and medially by the pterygoid and palatine bones,

Lower Jaw

The lower jaw (Plate 4, 5) is formed by two rami which unite anteriorly at the mental symphysis, and each extends posteriorly to articulate with the quadrate, Each ramus is composed of six bones: the angular, articular, coronoid, dentary, splenial, and surangular.

The dentary is largest and the only one to bear teeth (21 to 25 on a side). This variation was seen in all sand lizard genera. Measure- ments of the mandibular rami were taken, and the length was from the mental symphysis to the retroarticular process which extends posteriorly from the articulation with the quadrate. The width was considered to be the vertical distance from the dorsal edge of the coronoid process to the ventral edge of the angular. 21

Dentary

The dentary bone (Plate 4, 5) is largest of the lower jaw.

It bears the teeth and is found on both the medial and lateral side.

On the lateral side, it articulates with the angular ventrally, coronoid dorsally, and surangular posteriorly. From the medial aspect, it is seen to articulate with the coronoid dorsally, splenial posteriorly, and angular ventrally.

Its length was measured from the mental symphysis to the posterior extension of the bone on the lateral aspect. The width was the vertical distance of the bone just anterior to the coronoid process.

Articular

The articular (Plate 4, 5) occupies the posterior position on the lower jaw. It bears the articular condyles that meet the quadrate and it has two processes, the angular process and retroarticular process. The angular process is a stout tubercle that extends medially just anterior to the articular condyles. The surangular aids in the formation of this process. The second process, the retroarticular process, extends posteriorly, flattens, and twists horizontally. The articular joins the angular ventrally, surangular and coronoid dorsally, and splenial anteriorly, from the medial aspect.

From the lateral aspect it sutures with the angular and surangular.

The length is considered to be from the anterior extension of the bone to the posterior extension of the retroarticular process, and the width was measured just posterior to the angular process as a vertical distance. 22

Sur angular

The surangular (Plate 4,, 5) is located between the coronoid

and articular. It sutures with the coronoid, angular and articular.

It meets the angular only on the lateral side but articulates with the

other two bones on both lateral and medial sides. Fusion has occurred

in some between the surangular and articular on the lateral side making

exact determinations of the bone's extent difficult. Measurements were therefore taken from the medial side, The length was the distance

from the coronoid to the center of the angular process and the width was the vertical distance from the bone's ventral edge to the mandibles

dorsal edge.

Splenial

The splenial (Plate' 4) is a triangular-shaped bone found on

the medial side of the mandibular ramus, between two posterior exten-

sions of the dentary, ventral to an anterior extension of the coronoid

and articular, and dorsal to the angular. At its anterior extension

the splenial aids in forming the anterior inferior alveolar foramen.

Its length is the bones anterior-posterior extent and the width is

the ventral-dorsal distance.

Angular

The angular (Plate 4, 5) is a small splinter-like bone

found on the ventral edge of the lower jaw. Its posterior lateral

extension is relatively broad, while the anterior medial portion is

thin and narrow. On the medial side it articulates with the dentary, 23 splenial, and articular. On the lateral side the angular articulates with the dentary, surangular, and articular. The horizontal extension of the bone is the length. The widest point on the lateral surface was taken as the width.

Coronoid

The coronoid (Plate .4, 5) is located on the dorsal edge of the mandible. It consists of a coronoid process that projects into the temporal fossa just posterior to the ectopterygoid bone and anterior to the quadrate. It is one of the major points of attachment for the adductor muscle of the jaw. The coronoid articulates with the surangular posteriorly, articular ventrally and dentary anteriorly.

On the medial side it also meets the splenial at the coronoids most anterior projection.

Length was measured from the anterior to the posterior extremities from the medial aspect. Width was measured from the medial aspect and was the vertical distance at the central point of the coronoid process. The shape, size, and ratios of the lower jaw bones do not show significant variation. However, variation is seen .in the size of the entire nandible.

Teeth

Teeth are pleurodont and are borne by the dentary in the lower jaw and the maxilla and premaxilla in the upper jaw. There are no pterygoid teeth in the sand lizards, and the teeth of the sand lizards are without cusps. Some development of cusps is seen in Uma, and this development is only seen in the more posterior teeth. The 24 number of teeth is rather constant among the sand lizards. In the upper jaw, Callisaurus has 18 to 24 teeth, Cophosaurus has 19 to 21,

Holbrookia has 17-20, and Uma has 18 to 19. The lower jaw shows more consistency, with all the groups ranging from 21 to 25 teeth per side.

Hyroid Elements

The hyoids (Plate 6) are basically alike, predominantly cartilaginous and consisting of the: basihyal, glossohyal, hypohyal, ceratohyal, ceratobranchial I, and ceratobranchial II. The basihyal is a central disk. The glossohyal attaches to the basihyal's anterior edge and projects forward into the tongue mass. The hypohyal is paired and each cartilage extends laterally from the basihyal. The ceratohyals are attached to the hypohyal's lateral extent. They curve dorsally around the angle of the jaw extending into connective tissue posterior to the auditory cavity. The ceratobranchials are posterior extensions from the basihyal. The laterial pair (Certobranchial I) attach to the posterior edge of the basihyal and extends posteriolaterally and curve dorsJ.lly to be in close proximity to the ceratohyal in the connective t:issue behind the ear. The ceratobranchial II iE.: found in the midventra.l line extending posterior to the r;lavic~ es except in Holbroo1d a, where they fail to reach that ::ar. They are lor.gest in Callisaurus and UmA, shortest in

Holbrookia and intermeriiate in Cophosaurus, STATJSTICALANALYSIS

Osteology of the skulls was analyzed by taking 43 measurements from each skull and by calculating all possible ratios, Measurements were read into the computer which provided calculations and printed ratios in such a way that comparisons could be made between the lizard · groups. The statistical package for the social sciences (SPSS) discriminant analysis was employed to determine which ratios were of value in distinguishing genera and if the lizards could be classified by using them.

The theory and use of discriminant analysis is described by

Klecka (1975), and a discussion derived from his description follows:

Nine hundred and three ratios per skull were generated and those sufficient to separated one genus from the other three were used

Examples of ratios used in the analysis are presented in tables

1-22. The statistical program provides univariat F~ratios with 3 and 12 degrees of freedom for each variable. Means and standard deviation are also printed. The program forms one or more linear combinations of discriminating variables. These combinations are called discriminant functions and their number depends on the number of groups, in this case, 4, (number of groups-1 = number of discriminant functions) hence there are 3 discriminant functions.

The computer proceeds with the analysis in a stepwise fashion by selecting the single 'best~discriminating variable, and then selects a second one on the basis of its ability to improve the value of the

25 26 discrimination criterion in combination with the first variable,

Third and subsequent variables are similarly selected according to

their ability to contribute to further discrimination, At each step variables previously selected may be removed if found to reduce dis-

crimination when combined with more recently selected variables.

Eventually, either all variables will have been selected or it will be found that remaining variables are no longer able to contribute

to further discrimination. At this point, the stepwise procedure halts and further analysis is performed using only selected variables.

Classification coefficients are generated, and observations are classified according to these coefficients. A plot of the discriminant

score in two dimensions, a territorial map, and finally a classi-

fication based on the preceeding analysis is given.

Because of limitations of the SPSS program, no more than

12 ratios could be entered at a time. Therefore, the ratios were divided into 21 groups and the computer analyzed each group separately resulting in 21 tests. One hundred and sixteen ratios were selected as being capable of aiding in the group discrimination and discriminant score plots indicate how well each genus is discriminated. Care was taken to insure that the 116 ratios selected were all measuring different parameters in order to avoid unknown biases in the results.

An example of two discriminant score plots is given in fig. 23-24.

Each genus is represented by a number: 1 = Callisaurus, 2 = Copho-

saurus, 3 = Holbrookia, and 4 = Uma. An asterisk (the centroid) represents the center for that genus, and the distance between

centroids indicates the degree to which discrimination has been accomplished. Range, mean, and standard deviation of ratios for each 27 genus is presented in Tables III through XXIV along with a plot of the ratios (Figures 1 through 22) which illustrates relative relationships between genera.

These 22 tables and figures arri only examples of the 116 ratios and were selected because they clearly demonstrate the results referred to later.

Statistical results

U.sing the 116 ratios selected in the discriminant analysis, it

:ls pr,ssible to classify th•= four genera. 0£ 21 tests, classificatior. agreed with the present taxanomic system in 17 of them. The first classification error was in test number 7 where a Callisaurus a,_d a

Cophosaurus were both classified as Rolbrooki~. Only three ratios were involved and ,,,11 thri.:~e involved the squamo:;:;;_l width divided by the vomer width, palatine 1 mgth, and palatine ,ddth respectively.

These ratios were eff,:?ctive i:n separating Uma fro,:: the other three, but were net useful in distinguishing between the three. The Uma centroid avc-;;::.-aged4.13 mm away from tlk other three while the distance between th,2 Callis&.urus and Cop:1::tosaurus cent::.·1.1id.swas only O. 90 mm, b,:::tween Callisaurus and Holbrookia was 0.54 m:::, and between

Caphosaurus and Holbrookta w2.s 0.68 mm.

The secor._d class if icat:ion error was in test munber 8. Here a Callisaurus and a Holbrookia were both classified as Cophosaurus.

Four ratios were involved, and each one used the squamosal width divided by the pterygoid width, the epipterygoid width, and the hyoid length and the hyoid width. Whereas Uma was well separated in test number 7, this is not the case in test number 8. The average 28

separation of centroids was 0.87 mm for Uma, 0.73 mm for Callisaurus,

0.55 nun for Cophosaurus, and 0.73 mm for Holbrookia.

The most confused classification was in test number 15. Here one Callisaurus and one Holbrookia were both classified as Cophosaurus one Callisaurus was classified as Uma, one Cophosaurus was classified as Holbrookia, and one Holbrookia was classified as Callisaurus. Two ratios were used, and they were derived from the mandible width divided by the frontal width and the nasal width. Uma is the most distinct in this test, and the separation of centroids shows Uma averaging 4,32 mm from all other centroids, Callisaurus averaging

2.76 mm, Holbrookia 3.18 mm from the other centroids. The individual plot scores, hoever, show considerable variation and there is no discrete grouping to isolate the separate genera.

The last confused classification was test 17. Here four ratios were used which involved the mandible width divided by the palatine length, palatine width, epipterygoid length, and the mandible length. In this classification a Callisaurus and Cophosaurus were both mistaken for Holbrookia. The plot indicates a complete separation

of Uma, but with an overlap of the other three genera. The Uma centroid is 2.31 mm from the others, Callisuarus is·l.90 mm from

Cophosaurus and 1.35 mm from Holbrookia; Cophosaurus is separated from Holbrookia by 0.90 mm.

Over all 21 tests the centroids were separated on the average

of the following distances: Uma was separated from Callisaurus by

2.10 mm, from Cophosaurus by 2.44 mm, and from Holbrookia by 2.67 mm;

Callisaurus was separated from Cophosaurus by 1~19 mm, and from

Holbrookia by 1.58 mm; and Cophosaurus was separated from Holbrookia 29 by 0.92 mm. These centroids are derived from the discriminant functions which in turn are derived from linear combinations of the variables used in each test. The purpose for the discriminant analysis was to

find ratios that would discriminate between the groups, this goal was achieved. It is also desirable to determine how well each group is defined, and if it is significantly different from all other groups.

The SPSS program does not provide this information, but it is possible, by studying the plots, (Figures 1 through 22) to see that

the range of Callisaurus overlaps the range of Holbrookia and/or

Cophosaurus in nearly all ratios plotted. The range for Uma is only

occasionally overlapped by the other genera and it is usually only

Callisauru.s which overlaps Uma.

Uma is therefore the best differentiated by these tests.

The other three genera are close together and although they can be distinquished on the computer, their degree of separation is slight,

This separation is interpreted to indicate variation between species

and not between genera in the case of Cophosaurus, and Holbrookia.

Uma is considered to be a valid genus. 30

Platel- Dorsal view of skull.

A- Callisaurus BYD 3079 B- CoEhosaurus BYD 30518 c- Holbrookia BYU 15783 D- Uma BYU 3266

Key to the symbols used in Plate I. ec- ectopyerygoid fe- fenestra exonarina fm- foramen magnum fr- frontal ju- jugal mx- maxilla na- nasal ob- orbit pal- palatine par- parietal pf- parietal foramen pm- premaxilla pot- postorbital prf- prefrontal pt- pterygoid qu- quadrate stf- supratemporal fossa so- supraoccipital sq- squamosal 31

A ,•.:

B C

D 32

Plate 2. Ventral view of skull.

A- Callisaurus BYU 3079 B- CoEhosaurus BYU 30518 c- Holbrookia BYU 15783 D- Uma BYU 3266

Key to the symbols used in Plate II. bo- basiocc.ipital bp- basipterygoid process bs- basisphenoid co- columella ec- ectopterygoid ju- jugal mx- maxilla pal- palatine po- postorbital pp- parasphenoid process pr- pyriform recess pt- pterygoid qu- quadrate sq- squamosal vo- vomer 33

B C

D 34

Plate ,3-! Lateral view of skull.

A- Callisaurus BYU 3079 B- Co:2hosaurus BYU 30518 c- Holbrookia BYU 15783 D- Uma BYU 3266, CAS 42076 (insert)

Key to the symbols used in Plate III. co- columella ec- ectopterygoid ep- epipterygoid fe- fenestra exonarina fr- frontal ju- jugal mx- maxilla na- nasal ob- orbit pm- premaxilla po- postorbital prf- prefrontal pr- parietal pt- pterygoid qu- quadrate sq- squamosal 35

po- - ep_ ---ob --- _prl - - - -iu - - _no ____ pm ____ fc ---mx

A 36

Plate .4. Lateral view of mandible.

A- Callisaurus BYU 3079 B- Cophosaurus BYU 30518 C- Holbrookia BYU 15783 D- Uma BYU 3266

Key to the symbols used in Plate IV. an- angular ar- articular cor- coronoid de- dentary sr- surangular 37

or sr an de I I I I I I I I I

D 38

Plate 5. Medial view of mandible.

A- Callisaurus B'r.1.J 3079 B- CoEhosaurus BYU 30518 c- Holbrookia BYU 15783 . D- Uma BYU 3266

Key to the symbols used in Plate V. aif- anterior inferior alveolar foramen an- angular anp- angular process ar- articular condyle cor- coronoid de- dentary rap- retroarticular process sp- splenial sr- surangular 39

de CO r an s r anrP ~• ~ap I ajl I I I I I I I I I I I I ' I• I I l

D 40

Plate 6. Ventral view of hyoid.

A- Callisaurus BYU 3079 B- CoEhosaurus BYU 30518 c- Holbrookia BYU 15783 D- Uma BYU 3266

Key to the symbols used in Plate VI. bh- basihyal cb I- ceratobranchial I cb II- ceratobranchial II ch- ceratohyal gh- glossohyal hh- hypohyal 41

------9h

______hh ------_ b h - _- - -

______cbl

______cbll

B I A

D ,~2

Table 1

Ratio of the Skull Length Divided by the Haxillary Length Used in Test 113 of the Discriminant Analysis

Genus Range Mean Standard deviation

Callisaurus 1.8876 to 2.0976 2.0037 0.1073

Cophosaurus 1.8919 to 1. 9872 1. 9403 0.0416

Holbrookia 1.8358 to 2.0755 1.9440 0.1208

Una 1. 7lf51 to 1.8511 1. 7938 0. 0l}86

Total 1.7451 to 2.0976 1. 9205 0.1115

Callisaurus Cophosaurus ,--f= Holbrookia Uma

1.6 1.7 1.8 1. 9 2.0 2.1

Figure 1

Plot of Ratios Presented in Table 1 Table 2

Ratio of the Skull Length Divided by the Squamosal Width Used in Test #5 of the Discriminant Analysis

Genus Range Mean Standard Deviation

Callisaurus 9.6875 to 12.3636 10.8422 1.197 4

Cophosaurus 10.3333 to 13.8889 11. 7222 1.5437

Holbrookia 11. 5000 to 13.7500 12.1583 1.1751

Uma 5.4375 to 7.1379 6.1048 0.7827

Total 5.4375 to 13.8889 10.2069 2. 7175

Callisaurus Cophosaurus Holbrookia Uma

3 4 5 6 7 8 9 10 11 · 12 13 14

Figure 2

Plot of Ratios Presented in Table 2 Table 3

Ratio of the Skull Length Divided by the Quadrate Length Used in Test lf9 of the Discriminant Analysis

Genus Range. Hean Standard Deviation

C:lllisaurus 5.0588 to 5.4400 5.2734 0.1627

Cophosaurus 5.6818 to 7.0000 6.2150 0.6337

Holbrookia 5.0000 to 5.5000 5.2919 0.2102

Uma 4.4500 to 5.0488 4.8140 0.2666

Total 4.4500 to 7.0000 5.3986 0.6203

Callisaurus Cophosaurus + Holbrookia Uma

4.0 4.5 5.0 5.5 6.0 6.5

Figure 3

Plot of Ratios Presented in Table 3 45

Table 4

Ratio of the Skull Length Divided by the Mandible Length Used in Test 1!12 of the Discriminant Analysis

Genus Range Hean Standard Deviation

Callisaurus 0.9711 to 1.0382 1.0092 0.0322

Cophosaurus 1.0448 to 1.0515 1.0485 0.0032

Holbrookia 1.0391 to 1.1165 1.0687 0.0340

Uma 0.9539 to 1.0230 0.9915 0.0284

Total 0.9711 to 1.1165 1.0297 0.0400

Callisaurus er Co:ehosaurus + Holbrookia -+-- · Uma + 0.7 0.8 0.9 1.0 1.1 1.2

Figure 4

Plot of Ratios Presented in Table 4 46

Table 5

Ratio of the Skull Length Divided by the Mandible Width Used in Test #14 of the Discriminant Analysis

Genus Range Mean Standard Deviation

Callisaurus 4.5405 to 5.6667 5.0379 0.4923

Cophosaurus 5.2963 to 5.6000 5.4190 0.1337

Holbrookia 4.7500 to 6. 7647 5.5560 0.9255

Uma 4.0200 to 4.3500 4.1624 0.1373

Total 4.0200 to 6.7647 5. 01~38 0.7361

Callisaurus Cophosaurus Holbrookia Uma + 2 3 4 5 6 7

Figure 5

Plot of Ratios Presented in Table 5 47

Table 6

Ratio of the Skull Length Divided by the Hyoid Length Used in Test #18 of the Discriminant Analysis

Genus Range Mean Standard Deviation

Callisaurus 0.8037 to 1.0709 0.8912 0.1221

Cophosaurus 0.9936 to 1.0853 1. 0478 0.0399

Holbrookia 1.1176 to 1.37 50 1. 2811 0.1138

Uma 0. 7753 to 0.9054 0.8444 0.0557

Total 0.7753 to 1.3750 1.0161 0.1937

Callisaurus Cophosaurus Holbrookia + Uma +

4 5 6 7 8 9 10 11 12 13 14 15

F;i.gure 6

Plot of Ratios Presented in Table 6 Table 7

Ratio of the }is-:illary Length Divided by the Jugal Length Used in Te.st l/4 of the Discrirainant Analysis

Genus Range :Mean Standard Deviation

Callisaurus 0.8542 to 0.9368 0.8914 0.0430

CoEhosaurus 0.9012 to 0.9487 0.9268 0.0195

Holbrookia 0.8382 to 0.9178 0.8715 0.0386

Uma 0.9792 to 1. 0857 1.0401 0.0466

Total 0.8382 to 1.0857 0.9325 0.0756

Callisaurus -=:I Cophosaurus Holbrookia + =t= Uma

0.6 o. 7 0.8 0.9 1.0 1.1

Figure 7

Plot of Ratios Presented in Table 7 49

Table 8

Ratio of the H2...xillary Length Divided by the Quadrate Length Used in Test 114of the Discriminant Analysis

Genus Range Hean Standard Deviation

Callisaurus 2.4118 to 2.7813 2.6379 0.1710

Cophosaurus 2.9200 to 3.7000 3.2061 0.3610

Holbrookia 2.4783 to 2.9130 2.7303 0.20lf7

Uma 2.5500 to 2.7805 2.6826 0.0969

Total 2.4118 to 3.7000 2 .8llf2 0.3129

Callisaurus Co:ehosaurus + Holbrookia rp• + Uma + 0 l 2 3 4 5

Figure 8

Plot of Ratios Presented in Table 8 50

Table 9

Ratio of the Maxillary Length Divided by the Hyoid Length Used in Test #19 of the Discriminant Analysis

Genus Range Mean Standard Deviation

Callisaurus 0.3832 to 0. 5118 0.4448 0.0539

Cophosaurus 0.5000 to 0.5736 0.5405 0.0317

Holbrookia 0.6050 to 0. 7053 0.6589 0.0412

Uma 0.4270 to 0.5135 0.4714 0.0408

Total 0.3832 to 0.7053 0.5289 0.0936

Callisaurus Cophosaurus =i= Holbrookia =t= Uma

0.2 0.3 0.4 0.5 0.6 0.7

Figure 9

Plot of Ratios Presented in Table 9 51

Table 10

Ratio of the Jugal Length Divided by the Squamosal Width Used in Test #6 of the Discriminant Analysis

Genus Range Mean Standard Deviation

Callisaurus 5.4375 to 6.9091 6.0817 0.6713

Cophosaurus 5.6000 to 7. 7778 6.5271 0.9151

Holbrookia 6.7500 to 7.8750 7.1812 0.5250

Uma 3.0000 to 3.6207 3.2646 0.2783

Total 3.0000 to 7.8750 5.7637 1.6468

Callisauru-s Cophosaurus Holbrookia Uma + 2 3 4 5 6 7 8

Figure 10

Figure of Ratios Presented in Table 10 52

Table 11

Ratio of the Jugal Length Divided by the Quadrate Length Used in Test #10 of the Discriminant Analysis

Genus Range Mean Standard Deviation

Callisaurus 2.8235 to 3.0400 2.9581 0.0943

Cophosaurus 3.1818 to 3.9000 3.4554 o. 3271

Holbrookia 2.9565 to 3.2400 3.1301 0.1218

Uma 2.4750 to 2.7429 2.5816 0.1140

Total 2.4750 to 3.9000 3.0313 0.3670

Callisaurus -+ Co:2hosaurus + Holbrookia -+ Uma +

0 1 2 3 4 5

Figure 11

Plot of Ratios Presented in Table 11 53

Table 12

Ratio of the Jugal Length Divided by the Mandible Length Used in Test #10 of the Discriminant Analysis

Genus Range Mean Standard Deviation

Callisaurus 0;5491 to 0.5802 0.5660 0.0164

Cophosaurus 0.5676 to 0.5956 0.5834 0.0119

Holbrookia 0.6117 to 0.6602 0.6321 0.0206

Uma 0.4839 to 0.5690 0.5328 0.0363

Total 0.4839 to 0.6602 0.5786 0.0425

Callisaurus -+ Cophosaurus + Holbrookia + Uma + 1 2 3 4 5 6

Figure 12

Plot of Ratios Pres8nted in Table 12 54

Table 13

Ratio of the Squamosal Length Divided by the Squamosal Width Used in Test Jf7 of the Dif:c.rllllinant Analysis

Genus Range Mean Standard Deviation

Callisaurus 2.0625 to 2.8000 2.5445 0.3331

Cophosaurus 2.2667 to 3.0000 2.5987 0.3134

Holbrookia 2.5000 to 3.0000 2.6875 0.2394

Uma 1.2812 to 1. 7931 1. 5108 0.2116

Total 1.2812 to 3.0000 2.3354 0.5539

Callisaurus =t= Cophosaurus =t= Holbrookia + Uma + 0 1 2 3 4 5

Figure 13

Plot of Ratios Presented in Table 13 55

Table 14

Ratio of the Squamosal Width Divided by the Quadrate Length Used in Test #10 of the Discriminant Analysis

Genus Range Mean Standard Deviation

Callisaurus 0.4688 to 0.5517 0.4901 0.0478

Cophosaurus 0.4091 to 0.6250 0.5385 0.0972

Holbrookia 0.4000 to 0.4800 0.4374 0.0328

1Jma 0.7073 to 0 ..9143 0.7959 0.0876

Total OT4000 to 0.9143 0.5655 0.1560

Ca. I I Co. Ho. =t== Uma

\\ 0.4 0.5 0.6 0.7 0.8 0.9

Figure 14

Plot of Ratios Presented in Table 14 56

Table 15

Ratio of the Squamosal Width Divid~d by the Mandible Length Used in Test 1/13 of the Discrimina-rt Analysis

Genus Range Mean Standard Deviation

Callisaurus 0.0848 to 0.1067 0.0939 0.0105

Cophosaurus 0.0756 to 0.1014 0.0905 0.0111

Holbrookia 0.0777 to 0.0971 0.0885 0.0087

Uma 0,1336 to 0.1839 0.1647 0.0239

Total 0,0756 to 0.1839 0.1094 0.0356

Ca. Co.----'==t==="--- Ho. =I Uma

.07 .09 .11 .13 .15 .17

Figure 15

Plot of Ratios Presented in Table 15 57

Table 16

Ratio of the Squamosal Width Divided by the Hyoid Length Used in Test #20 of the Discriminant Analysis

Genus Range Mean Standard Deviation

Callisaurus 0.0769 to 0.0866 0.0821 0.0047

Cophosaurus 0.0769 to 0.0962 0.0902 0.0090

Holbrookia 0,1000 to 0.1163 0.1056 0.0075

Uma 0.1086 to 0.1561 0.1403 0.0217

Total 0.0769 to 0.1561 0.1046 0.0256

Callisaurus + Co:ehosaurus Holbrookia =t= Uma

.06 .08 ,10 .12 .• 14 ,16

Fignre 16

Plot of Ratios Presented in Table 16 58

Table 17

Ratio of the Quadrate Length Divided by the Quadrate Width Used in Test #11 of the Discriminant Analysis

Genus Range Mean Standard Deviation

Callisaurus 1.2800 to 1. 6667 1.4794 0.1884

Cophosaurus 1.3333 to 1.4706 1.4010 0.0782

Holbrookia 1.4706 to 2.0000 1. 7301 0.2669

Uma 1. 6400 to 1.8421 1. 7451 0.1001

Total 1.2800 to 2.0000 1.5889 0.2214

Callisaurus Cophosaurus =t= Holbrookia Uma

2.0 .1.0 1.2 1,4 1.6 1.8

Figure 17

Plot of Ratios Presented in Table 17 59

Table 18

Ratio of the Quadrate Length Divided by the Mandible Length Used in Test #11 of ths Discriminant Analysis

Genus Range Mean Standard Deviation

Callisaurus 0.1850 to 0.1965 0.1914 0.0049

Cophosaurus 0.1493 to 0.1849 0.1700 0.0173

Holbrookia 0.1942 to 0.2233 0.2067 0.0173

Uma 0.1889 to 0.2299 0.2067 0.0173

Total 0.1493 to 0.2299 0.1926 0.0195

Callisaurus =f= Cophosaurus Holbrookia Uma

.12 .14 .16 .18 ·.20 .22

Figure 18

Plot of Ratios Presented in Table 18 60

Table 19

Ratio of the Quadrate Length Divided by the Hyoid Length Used in Test #11 of the Discriminant Analysis

Genus Range Mean Standard Deviation

Callisaurus 0.1551 to 0.1969 0.1687 0.0191

Cophosaurus 0.1538 to 0.1880 0.1698 0.0180

Holbrookia 0.2101 to 0.2674 0.2424 0.0240

Uma 0.1536 to 0.1951 0.1761 0.0194

Total 0.1536 to 0.2674 0.1893 0.0366

Ca Co--====i::==1--- Ho Um------'===t====----

.16 .18 .20 .22 .24 .26

Figure 19

Plot of Ratios Presented in Table 19 61

Table 20

Ratio of the Mandibh! Length Divided by the Mandible Width Used in Test 1.117 of the Discriminant Analysis

Genus Range Mean Standard Deviation

Callisaurus 4.6757 to 5.4583 4.9849 0.3426

Cophosaurus 5.0370 to 5.3600 5.1686 0.1394

Holbrookia 4.6800 to 6.0588 5.1828 0.6954

Uma 4.0400 to 4.3750 4.2004 0.1820

Total 4.0400 to 6.0588 4 .8842 0.5509

Callisaurus Cophosaurus Holbrookia Uma

4.0 4.4 4.8 5.2 5.6 6.0

Figure 20

Plot of Ratios Presented in Table 20 62

Table 21

Ratio of the Mandible L,2ngth Divided by the Hyoid Length Used in Test #21 of the Discriminant Analysis

Genus Range Mean Standard Deviation

Callisaurus 0.8021 to 1.0315 0.8823 0.1067

Cophosaurus 0.9487 to 1. 0388 0.9993 0.0386

Holbrookia 1.0756 to 1. 2875 1.1981 0.0897

Uma 0.8127 to 0.9099 0.8512 0.0419

Total 0.8021 to 1.2875 0.9827 0.1558

Callisaurus Cophosaurus =t= Holbrookia Uma =t=

0.7 0.8 0.9 1.0 1.1 1. 2

Figure·21

Plot of Ratios Presented tn Table 21 63

Table 22

Ratio of the Hyoid Length Divided by the Jugal Length Used in Test 1119of the Discriminant Analysis

Genus Range Mean Standard Deviation

Callisaurus 0.4486 to 0.5984 0.4998 0.0676

Cophosaurus 0.5385 to 0.6047 0.5832 0.0303

Holbrookia 0.6807 to 0.7907 0.7568 0.0517

Uma 0.3933 to 0.4829 0.4538 0.0421

Total 0.3933 to 0.7907 0.5734 0.1274

Callisaurus Cophosaurus Holbrookia + Uma =i=

.30 .40 .50 .60 .70 .80

Figure 22

Plot of Ratios Presented in Table 22 64

: -- -J.O00 ______-1 .~oo -·-···--·-··O,O ______J,.!IO.CI______J.9_0Q___ _ •------•------•-~------•------♦------•------•------•------~• l.coo 1 1 3,000 ----:------~----

I 'I 2.7.50 I I I I I I I l.~Ov I I 1.soo I I I I I I I I I I 0.75J I I 0.750 I L ___ _ I I I I I 2•3 I ______I ------"j·i_ I 0,0 I I I I 4,______I ___ o.o_ l -----,.1 4* i l I l;,___ .,_1______,1 I I -0.750 I I -C.750 I ····- ! ______I I I I I ______I ______I I I 1-1.50? I I -l.500 I ______! ____ _ I I ! !---~------:------1-z.z5~1 1 -2.;so r. I ··------·----- _it ___ _ I l I ~----- '·------·-··-··-·--·---···-··------·· ---- ______1______1 I I i-J.000 '•------+------•------•------•------•------•------•------•I -3.000 -i.>.s-.:, · - -J.1s0 o.1~c - 2:z.50--·

Figure 23

Plot of Discriminant Sc.ore 1 (horizontal) vs. Discriminant Sc.ore 2 (vertical). * indic:-,tes a Group Centroid From Test 113 65

-1_.000 -1.2so 0.500 2.2~0 ___ ,,.::,oo ♦------•------♦ ------♦ ------·------+------t ------·_ •------♦ ".00<) I I 4,:oo ___ !,______I I I I I I I I I 3.125 I I 3. 12$" '-1------,----I I I I I __ I! ___ _ 2.250 I l 2.2,0 I

I I I -- I 1.175 I I 1.315 I I I I I 1 ----C::'------} o.soo I I 'J. sco l I ----:' I l I 7 I l I -0.; 75 I I -0.375" I • l I I I . I I _____ jI ______I!______

: -1.25, : I -1.2~0 I I I I I 1 I I ------.------'.-2.125 I I -2.125 ; I I ; ------,------··1 . I I r-----i. I ------r-•------I j-J .on I I -J.CCO ------·-.;;z;rzs---·♦------•------♦------•------:..,, J15·------·------♦------♦------1·.11s··------,~uo;------♦------•------•

Figure 24

Plot of Discr:i.rninant Score 1 (hcrizontal) vs. Discri.minant Score 2 (verttcal). * Indicates a Group Centroid From Test //4 MYOLOGY

Terminology used in this section follows that of Robison

and Tanner (1962), Avery and Tanner (1971) and Jenkins and Tanner

(1968).

Muscles of the Throat

The intermandibularis muscles are superficial muscles of

the throat and include the intermandibularis anterior superficialis,

intermandibuJaris anterior profundus, and intermandibularis posterior.

They originate on the mandibular rami, and all insert :ln the ventral midline raphe.

M. Intermandibula:ds anterior superficialis (Plate 7, 11) is

a small muscle which originates on the medial side of the mandibular

ramus, approximately one-fourth the d:i.stance from the mental symphysis

to the angle of the jaw, In Uma it has a distinct fan-shape, the

insertion being two and one-half times wider than the origin. In

Cophosaurus it is only slightly fan-shaped and originates .slightly

anterior and ventral to the intermandibularis a:nterior profundus with

fibers extending posteromedial. The origin in Cophosaurus is ha]f

the width of the insertion. Its origin is the same in Callisaurus,

as it is in Cophosuaurs> but it is not fan-shaped, In Holbrookia it

is not fanshaped and the origin is ventral to the intermandibularis

anterior profundus with its fibers passing posteromedially.

M. Intermandibularis anterior profundus (Plate 7, 11)

originates on the medial side of the mandibular rami) and occupies a

position from approximately one-fourth to one-half the distance from

66 67 the mental symphysis, to the angle of the jaw. It is deep to the intermandibularis anterior superficialis, which is located at its anterior end, and the intennandibularis posterior is at its posterior end. The posterior origin of the muscle interdigitates with the origin of the mandibulohyoideus I.

In Uma the muscle fibers.of the intermandibularis anterior profundus extend medially with only a few fibers at each end fanning out. The origin to insertion ratio in Uma is close to 1. In

Cophosaurus this muscle is distinctly fan-shaped and the origin is two and one-half times the insertion. It is also fan-shaped in

Callisaurus with an origin to insertion ratio of 1.6. More than one- halp of the origin is deep to the mandibulohyoideus I in Holbrookia.

The muscle here is slightly fan-shaped with most fibers slanting posteriorly. The ratio is slightly more than 1.

!!• Mandibulohyoideus _! (Plate 7, 11) originates on the ventral side of the mandibular ramus; its origin is superficial to the intermandibularis anterior profundus, and its most anterior fibers originate at the posterior edge of the intermandibularis anterior superficialis. This muscle is a triangular muscle and inserts on the distal three-fourths of the first ceratobranc:hial of the hyoid apparatus.

The mandibulohyoideus I is deep to the intermandibularis posterior and also the anterior ventral portions of the depressor mandibularis. It interdigitates with these to insert on the lateral side of the articular process of the lower jaw. It is superficial to the genioglossus, hyoglossus, mandibulohyoideus III, and pterygomandibularis muscle, and lies lateral to the mandibulohyoideus II. 68

M, Mandibulohyoideus II (Plate 11) originates in the mid- ventral raphe and inserts on the anterior fourth of the first ceratobranchial of the hyoid apparatus. This is a small narrow muscle that lies medial to the first mandibulohyoideus muscle. The insertions of these two muscles are continuous on the first ceratobranchial.

M. Mandibulohyoideus III (Plate 9, 12) is a small strap like muscle found deep to the lateral edge of the mandibulohyoideus I and lies between the hyoglossus and pterygomandibularis muscle. Its position is lateral to the former and ventromedial to the latter.

This muscle originates anterior to the pterygomandibularis muscle on the ventral surface of the mandibular rami, and inserts on the distal end of the ceratohyal of the hyoid apparatus.

M. Genioglossus (Plate 7, 11) occupies the anterior end of the throat region and is the superficial muscle of the throats anterior quarter. This muscle originates on the ventral side of the ramus from the symphysis to' the anterior edge of the intermandibularis anterior superficialis. The genioglossus overlays the ventral surface of the tongue and inserts by interdigitating through the hyoglossus at the level of the basihyal, and is deep to the intermandibularis and the mandibulohyoideus muscles. Another portion of this muscle extends from the ramus dorsally into the body of the tongue.

~- Hyoglossus (Plate 9, 12) forms the main body of the tongue, and originates on the first ceratobranchial, interdigitates with the genioglossus and passes into the tongue where it inserts. The hyoglossus is deep to the mandibulohyoideus I and II and medial to the pterygomandibularis and mandibulohyoideus III. 69

M. Branchiohyoideus (Plate 13) occupies the space between

the ceratohyal and the first ceratobranchial of the hyoid apparatus.

It has a narrow origin on the ceratohyal and hypohyal and a broad insertion on the certobranchial. This muscle is ventral to the oral membrane.

M. Omohyoideus (Plate 9, 11) originates on the scapula and clavicle and inserts on the distal portion of the first ceratobranchial. Midway between the origin and insertion it is bisected by a myocomma, which binds the muscle fibers together. This myocomma also bisects the sternohyoideus muscle, and the two muscles are bound firmly together by it.

The omohyoideus can be easily separated from the sternohyoideus posterior to the myocomma, but it is difficult to distinguish the two muscles anterior to the myocomma.

The omohyoideus' takes two forms, in Uma and Holbrookia it

has a single head originating on the scapula and clavicle. In Calli-

saurus, Cophosaurns, and some Holbrookia individuals, the omohyoideus

is divided for its entire length, connected only by the myocomma.

The medial portion of ·the omohyoideus cannot be distinguished from the

sternohyoideus anterior to this myocornma in all gen,.=.ra.

M. Sternohyoideus I (Plate 9, ll)originates on the sternum and inserts on the proximal end of the ceratobranchial I and II.

There is a myocomma at its junction with the omohyoideus which unites the two muscles.

The sternohyoideus and omohyoideus are closely related and there is considerable confusion in the literature concerning them.

The position taken here is that those portions that originate on the 70

scapula and clavicle are omohyoideus and those portions that originate

on the sternum are sternohyoideus.

Both muscles are deep to the constrictor colli, and the

episterno-cleidomastoideus is ventral to them. The muscle dorsal

to them is the sternohyoideus II.

Sternohyoideus II (Plate 10, 12) originates on the sternum

and has a broad insertion on the first ceratobranchial. This is a

fan-shaped muscle. It is dorsal to omohyoideus and sternohyoideus I

and is ventral to the oral membrane.

The Neck Muscles

M. Constrictor colli (Plate 7, 11) is the superficial muscle of the neck, originating in the dorsolateral fascia of the neck

and inserting in the ventral raphe of the throat posterior to the

intermandibularis posterior. It is one or two muscle fibers thick,

rather narrow, and the origin is broader than the insertion.

In all four genera the muscle fibers of the constrictor colli reach the mid-throat area, but dorsally they fail to reach the middle

of the neck.

The constrictor colli is widest in Uma. It covers from the posterior edge of the tympanum to the shoulder nearly covering completely the depressor mandibular is. In the other three genera it

is more strap-like, and only fills half the space between the posterior

edge of the tympanum and shoulder, being centered in this area.

M. Depressor mandibularis (Plate 7) originates in the mid- dorsal raphe, along the posterior borders of the parietal bone and parietal wings. The insertion has three slips, one inserts deep to 71

the pterygomandibularis on the articular process of the lower jaw.

Another passes superficially to the pterygomandibularis and the

intermandibularis posterior to insert on the ventrolateral surface of

the mandibular rand by interdigitating at right angles with these muscles. The third slip inserts on both sides of a tendon that

extends dorsally from the articular process. The attachment of this

slip to the articular is superficial to the deep slip mentioned above.

M. Episternocleidomastoideus (Plate 8) is a strap-like muscle that extends from the posterior margins of the skull to the

sternum and clavicle. It is deep to the depressor mandibularis and

superficial to the omohyoideus and sternohyoideus already mentioned,

The posterior fibers of this muscle are continuous with the most anterior fibers of the trapezius.

Its origin in Callisaurus is along the posterior margin of

the parietal bone, parietal wings, and with an almost equal number of

fibers originating in the mid-dorsal raphe. In Cophosuarus very few fibers originage in the raphe. Nearly all of its fibers originate on

the parietal bone and parietal wings in Holbrookia, and in Uroa the

origin is along the parietal wing and mid-dorsal raphe, with very

few fibers reaching the posterior margin of the parietal bone.

The remaining deep muscles of the neck will not be described here.

Temporal Musculature M. Pterygomandibularis (Plate 8, 11) is a large massive muscle located at the angle of the jaw. It originates on the pterygoid

and by a strong tendon to the ectopterygoid. Its fibers extend 72

ventrally to form a sling around the posterior end of the mandibular

ramus. The insertion is on the articular process from the ventro-

lateral margin to the dorsolateral margin and portions of the quadrate

proximal to the condyle.

The adductors of the mandible fill the supratemporal and

infratemporal fenestras. They consist of four muscles: adductor mandibularis externus superficialis, adductor mandibularis externus medius, adductor mandibularis externus profundus, and adductor mandibularis posterior. The origins of these muscles are on the

quadrate, parietal and parietal wings, jugal, squamosal, tabular,

opisthotic, prootic, and exoccipital complex,

This set of muscles are deep to the levator angularis oris, which is a small muscle that stretches in a triangular shape from the

point of the jugal to the midlateral edge of the quadrate and squamosal. There is a stout tendon that is attached at the point of the

jugal and extends to the ventrolateral edge of the quadrate which

appears to be part of the levator angularis oris.

M. Adductor mandibularis externus superficialis (Plate 8)

is deep to the levator angularis oris. It comprises most of the bulk

of the adductor mandibular complex. The fibers of this muscle origin-

ate on the jugal, squamosal, and parietal wing and insert on the

lateral surfaces of the surangular, coronoid, and angular.

M. Adductor mandibularis externus medius (Plate 8) is medial to the superficialis and originates on the parietal and

quadrate. This muscle inserts on the dorsomedial surface of the

surangular and posterior surface of the coronoid. 73

M. Adductor mandibularis posterior (Plate 10) originates

from the anterior edge of the quadrate and part of the prootic, and

inserts on the dorsal surface of the articular. This muscle occupies

the posterior portion of the angle between the quadrate and lower jaw.

The adductor muscles are not distinct from one another and

there is some confusion in the literature concerning the nomenclature

of these muscles.

M. Levator pterygoideus (Plate 10) is a small muscle associ-

ated with the epipterygoid. Its fibers originate on the anterior edge

of the epipterygoid, the descending process of the parietal, and

prootic. The insertion is on the medial and lateral surface of the

pterygoid,

M. Protractor pterygoideus (Plate 10) is another small muscle associated with the epipterygoid. The fibers of this muscle

originate on the posterior edge of the epi.terygoid and prootic. They

insert along the posterior portion of the quadrate process of the

pterygoid. 74

Plate 7. Lateral view of head and neck musculature; superficial depth.

A- Callisaurus BYU 2943 B- Co:ehosaurus BYU 30512 c- Holbrooki.a BYU 15782 D- Uma BYU 3263

Key to the symbols used in Plate VII. am- adductor mandibularis externus medius as- adductor wandibularis externus superficialis au- auditor_y meatus cc- constrictor colli dm- depressor mandibularis ep- episternocleidomastoideus gg- genioglossus iap- intermandibularis anterior profundus ias- intermandibularis anterior superficialis ip- intermandibularis posterior la~ levator angularis oris mh I- mandibulohyoideus I 75

L------'----iP A

D 76

Plate 8. Lateral view of head and neck musculature; first depth.

A- Callisaurus BYU 2943 B- Copkosaurus BYU 30512 C- Holbrookia BYU 15782 D- Uma BYU 3263

Key to the symbols used in Plate VIII. am- adductor mandibularis externus medius as- adductor mandibularis externus superficialis ep- episternocleidomastoideus gg- genioglossus mh I- mandibulohyoideus I oh- omohyoideus pm- pterygouandibularis sh- sternohyoideus II tr- trapezius 77

A ! . '

C B

D 78

Plate 9. Lateral view of head and neck musculature; second depth.

A- Callisaurus BYU 2943 B- Cophosaurus BYU 30512 C- Holbrookia BYU 15782 D- Uma BYU 3263

Key to the symbols used in Plate IX. am- adductor mandibularis externus medius as- adductor mandibularis externus superficialis gg- genioglossus hg- hyoglossus mh III- mandibulohyoideus III oh- omohyoideus pm- pterygomandibularis sh- sternohyoideus II 79

0 80

Plate 10.~. Lateral view of head and neck musculature; third depth.

A- Callisaurus BYU 2943 n- Cophosaurus BYU 30512 C- Holbroolcia BYU 15782 D- Uma BYU 3263

Key to the symbols used in Plate X. ap- adductor mandibularis posterior hg- hyoglossus lp- levator pterygoideus pm- pterygomandibularis pp- protractor pterygoideus sh- sternohyoideus II 81

ap __ -

-- ___ hg

C 8

D 82

Plate 11 Ventral view of throat musculature; superficial layer at left and first depth at right.

A- Callisaurus BYU 2943 B- Cophosaurus BYU 30512 C- Holbrookia BYU 15782 D- Uma BYU 3263

Key to the symbols used in Plate XI. cc- constrictor colli dm- depressor mandibularis ep- episternocleidomastoideus gg- genioglossus iap- intermandibularis anterior profundus ias- intermandibularis anterior superficialis ip- intermandibularis posterior mh I- mandibulohyoideus I mh II- mandibulohyoideus II oh- omohyoideus pm- pterygomandibularis sh I- sternohyoideus I sh II- sternohyoideus II 83

n C·

D 84

Plate 12·- Ventral view of throat musculature; second depth at left and third depth at right.

A- Callisaurus BYU 2943 B- Cophosaurus BYU 30512 C- Holbrookia BYU 15782 D- Uma BYU 3263

Key to the symbols used in Plate XII. gg- genioglossus hg- hyoglossus mh III- mandibulohyoideus III pm- pterygomandibularis sh- sternohyoideus II 85

n C

D 86

Plate 13. Ventral view of throat musculature; fourth depth at left and fifth depth at right.

A- Callisaurus BYU 2943 B- Cophosaurus BYU 30512 C- Holbrookia BYU 15782 D- Uma BYU 3263

Key to the symbols used in Plate XIII. bh- branchiohyoideus hy- hyoid pm- pterygomandibularis 87

D 88

Platel4 Dorsal view of head and neck musculature; superficial depth at left and first depth at right.

A- Callisaurus BYU 2943 B- Cophosaurus BYU 30512 C- Holbrookia BYU 15782 D- Uma BYU 3263

Key to the symbols used in Plate XIV. am- adductor mandibularis externus medius cc- constrictor colli dm- depressor mandibularis ep- episternocleidomastoideus tr- trapezius 89

B C 90

Plate 15 Dorsal view of head and neck musculature; second depth at left and third depth at right.

A- Callisaurus BYU 2943 B- Co2hosaurus BYD 30512 c- Holbrookia BYU 15782 D- Uma BYU 3263

Key to the symbols used in Plate XV. am- adductor mandibularis externus medius as- adductor mandibularis externus superficialis cm- cervicomandibularis lp- levator scapulae profundus ls- levator scapulae superficialis re- rectus capitus anterior sp- spinus dorsi 91

D DISCUSSION

Sand lizards are a closely related group accordiug to Smith

(1946); Norris (1958); Axtell (1958); Etheridge (1964); Clarke (1965).

Smith referred to them as a closely knit group and listed their common characteristics as being: oblique labials, granular dorsal scales, small head ~cales, a gular fold, a peculiar median triangular post- mental, several prominent post labials, much the same habits, sirailar habitat, scoop-shaped heads, flaring labial regions, and a counter- sunk lower jaw. Axtell (1958) listed 22 characters that he felt would describe ancestral sand lizards as follows:

1. Small unequal dorsal head scales, large interparietal.

2. Head high, elongate, keeled supralabilas, blunt snout.

3. Mental scale subject to division.

4. Several rows of enlarged sublabials.

5. Temporal region covered with enlarged scales.

6. Dark iris.

7. Well developed gular fold, with pregular fold.

8. Small granular, keelless dorsal scales of uniform size.

9. Moderately developed lateral derr:ial fold.

10. All sclaes with an opaque color background.

11. Ventral scales flat, keelless, and slightly imbricate.

12. A rather high number of uell developed femoral pores.

13. Enlarged post anal scales present in males.

92 93

14. Tail the sar.:1e length as bccy, keeled dist.illy.

15. Dorsal pattern of distinct, dark, bands or blo~ches.

16. Lateral abdc~inal markings rlark with a colore~ areola.

17. Ventral scales ,:hite with carker chin and gular markings.

18. A dorso-ventrally flatte.r:ed body, well develo?ed limbs.

19. Visible ty::ipa2uCT margined by enlarged auricu:!...e.r scales.

20. Xasal openings dorsal, ",:al·1e 11 for closure

21. No teeth on tte palate.

22. A:!1terior nylohyoid muscle of the throat, dege::erate.

Although Callisaurus is specic.lized, it is siL1il2.r to the

primitive condition in that it exhibits :::2ny of the characteristics ncutioned by Axtell in his description of the p:r.imi t:i.ve £,,ces tor.

Its specializations are se~3 in increased length of tail &nd li~bs,

giving it a sler.c.er body form. Eolbrookia is also similar e:-:ce:;-;t for

the covered tympanum. Body form is not as proportionately slender

ns Callisaurus, nor is the tail as long. The problematic Cci:::osaurus hP-s characteristics of both. Its body fo-r:::i, linbs and tail, 2.pproc..ch

Callisaurus but it has a covered tympan...:.::1 like Holbrookia. c::-,a has developed, to a greater degree, the

Cophcsaurus) occupy generalized habitats, probably similar to primitive habitat occupied by their pr0genitors. 'C=a, on the other hc:::c., is restricted to that of sand ~unes. With o~ly slight exceptio~s this list of characters eight just as ~ell apply to ether scelcporine l~zards. 94

Osteology

Based on comparisons of skulls of Sauromalus (Avery and

Tanner, 1964) and Ctenosaura (Oelrich, 1956), and general accounts of reptile osteology by Williston (1925) and Romer (1956);, Avery and

Tanner indicated that osteological characteristics of iguanid lizard skulls are stable within genera. Studies on Sauromalus (Avery and

Tanner, 1964}, Croto_phytus (Robison and Tanner, 1962), and Ctenosaura

(OeJ.r;i.ch, 1956) portrayed the apparent general stability of osteological characters found in iguanid skulls however, skulls of Calli- saurus, Cophosaurus, Holbrookia, and Uma observed in this study are peculiar to iguanid skulls as portrayed by the above authors in that the lacrimals and postfrontals were absent. This condition was also found in Phrynosoma by Jenkins and Tanner (1968) and in sand lizards by Etheridge (1964).

Deviation by sand lizards from the general iguanid skull, particularly evidenced by the fusion or loss of the lacrimal and postfrontal bones, is evidence supporting the hypothesis that sand lizards are highly specialized among the iguanids.

ln discussing the osteology of Holbrookia, Axtell (1958:24) stated:

"In general tfte osteology of the genera Callisaurus and Ur.!.a corresponds closely with that of Holorookia, so this discourse may apply just as well to the entire sand lizard section of the fam:i,.ly iguanidae."

Development of the covered tympanuu appears to be· related to osteological variations observed. The quadrate, squamosal, para- occj_pital process, and mandible arc all adjacent to the ear, and all

With the loss of the exhibit variations (~lates 1 ' 3 , 4 ' 6) 95 external ear, the quadrate is reduced in sLze, and the paraoccipital process directed forward, the mandible shortened, the squamosal narrowed, and the hyoid also shortened. These modifications of the skull are apparent in earless sand lizards, and less modified in forms having an external ear. Callisaurus and Uma are alike in that the paraoccipital process is directed caudad, the qua.drate proportionately larger, and the ffiandible land and wide (Plates 1, 3, 4, 6). In

Uma the degree of development of these characters was different, in that the squamosal is wide. A ratio of skull length divided by squamosal width shows: (A) Uma ranging from 5.4375 to 7.1379;

(B) Callisaurus from 9. 697 5 to 12 .3636; (C) Cophosaurus from 10. 3333 to 13.8889 and (D) Holbrookia 11.0833 to 13.7500 (from Table 4). The quadrate and mandible length and width are similarly enlarged in Uma when compared to other groups (Tables 3 through 24). These differences are sufficient enough that the computer is able to readily distinguish between them and those same characteristics found in Callisaurus and the earless group.

There is some variation in the position and articulation between the squamosal, jugal, and postorbital; but in all cases, with the exception of Uma, the jugal reaches the squamosal, and in Calli- saurus it edges between the squamosal and postorbital. In Holbrookia and Cophosaurus the degree of encroachment is increased. This may be due to the forward direction taken by the paraoccipital process. Again

Uma is unique in th-'lt the jugal fails to reach the squamosal in some individuals, in which case the postorbital is found wedging between them (Plate 3). 96

Myology

The literature is void of studies dealing directly with

myology of sand lizards. Earle (196la,b,c, 1962), dealt with the

middle ear, and also touched on the myology in the ear region. In

this study, I will deal only with the myology of the head and neck

region. A comparison of the anterior anatomy of sand lizards shows

some observable differences which are discussed and figured.

The intermandibularis muscles show some variations which are

useful in distinguishing each genus from the others. Uma is most

distinct, with its intermandibularis muscle being fanshaped (Plate 11).

This condition is contrasted with that found in Holbrookia where it

is difficult to distinguish one muse.le from the other. The fibers are

all so nearly parallel that the borders of each transverse mandibulae muscle is difficult to discern. Cophosaurus and Callisaurus exhibit

an intermediate condition with some fanning seen, but not to the

extend seen in Uma. Cophosaurus can be distinguished from Callisaurus

in that fibers of the interrnandibularis anterior superficialis extend

posteromedially, and in Cophosaurus a portion of the insertion of the

interrnandibularis anterior profundus is found anterior to the super-

ficialis, a condition not seen in Callisaurus.

The depressor mandibulae also shows some variations. In

the earless lizards there is an expanded anterior edge of this muscle

which partially covers the enclosed tympanum. This muscle emerges

from beneath the constrictor colli to insert upon the mandible with

its most ventral fibers interdigitating at right angles with the inter-

mandibularis posterior. Furthermore, the depressor mandibulae fibers

extend much further along the mandibular ramus than in the other two 97 genera. In Cophosaurus these fibers reach the mandibular ramus with only a few interdigitating with the intermandibularis posterior.

The omohyoideus is also variable in these genera. In the unfolding of the evolutionary development of the omohyoideus a branch of the rectus cervicus originated on the scapula and inserted on the hyoid, In sand lizards there is a complex of muscles that are related to this one. In~ the omohyoideus has a second head that originates on the sternum. This then can be called a sternohyoid, Another muscle (thyrohyoideus Avery 47-1964) arising on the sternum passes deep to this sternohyoid head of the omohyoideus and inserts on the posterodorsal edge of the ceratobranchial I. In sand lizards, it clearly originates on the sternum, and in this study is designated as the sternohyoideus II.

A division of the omohyoideus has occurred in Callisaurus,

Cophosuarus, and two specimens of Holbrookia. (Holbrookia lacerta CAS

73979, and Holbrookia b, approximans BYU 17099). Thus, in sand lizards the muscle may have one to three origins: the most lateral dorsal one is on the scapula, the second on the clavicle, and most medial on the sternum and interclavicle, The omohyoideus also has two insertions, the most lateral division inserts on the distal two-thirds of the ceratobranchial I, and the second and medial heads unite and insert on the proximal third of the ceratobranchial II and basihyal. In

Uma and for the most part in Holbrookia, such division of the omo- hyoi.deus has not occurred, and the insertion is continuous along the ceratobranchial I, the basihyal, and proximal third of the certobranchial U. 98

Phylogeny

Norris (1958) and Axtell (1958) agreed that sand lizards began their radiation in early or middle miocene. This is the time when the

Sierra Madre Occidental range of Mexico was being built by vo.lcanism along the western and southern borders of the Mesa of Central Mexico

(Schuchert, 1935 and Miller, 1942). Axtell indicated that this vol- canism split sand lizards into groups, a Uma-Callisaurus group and a

Holbrookia prototype. Norris also believed the sand lizards were divided at this time but indicated that Uma was isolated from the

Callisaurus-Holbrookia stock. Norris further indicated that Uma was subsequently split by continued mountain building processes in ~he mid-Pliocene giving rise to the exsul group and notata-scoparia stocks.

He also postulated that it was during this same time that the Calli- saurus-Holbrookia stock was divided. Axtell rs concepts are unacceptable in the light of this study. According to Maslin (1952)

"The basic assumption upon which all taxonomic practices rest is that similar organisms are related." If we assume that sand lizards have occupied similar habitats and have been subject to similar environ- ments throughout their recent history, then we can assume that the degree of similarity between groups is an indication of the closeness of their relationship. Maslin (1952) also said that because internal characters are less variable, they are of much greater value in establishing relationships than external characters. The internal characters considered here indicate a closer relationship between

Holbrookia ai:d Cal 1 isaurus, than between Uma and Callisaurus, indicating that Uma was probably the first of the sand lizards to break away from the ancestral line. 99

Clarke (19-65) examined the behavior and external morphology from the standpoint of 20 characters, in 14 of them Cophosaurus was like Callisaurus, in 5 of them Cophosaurus was unique, and in only one

Cophosaurus was like Holbrookia. In discussing these comparisons he states:

"The distinctness of Cophosaurus is evident. It is intermediate in ttany features between Callisaurus and Rolbrookia, with the data indicating a closer affinity to CaJlism.:rus than to Holbrookia. The uniqueness of Cophosaurus is most clearly shown in the distinctness of the push-up pattern.

On the basis of five characters, Clarke would separate

Cophosaurus as a separate genus. These five characters are: (1) placement of the lateral bar: anterior for Callisaurus, posterior for Cophosaurus and central for Holbrookia. (2) body shape: slender for Callisaurus, intermediate for Cophosaurus, and stout for Hol- brookia. (3) roid~le ear: distinct for Callisaurus with an external opening, distinct for Holbrookia without an external opening, and intermediate for Cophosaurus without an external opening. (4) pre- ferred body temperature~ 39.2°c. for Callisaurus, 38.3°c. for

Co phosaurus, and 35. 7-38 .1 °,:::.for Holbrookf.a. (5) p:ish-up pattern: dist:Lnct in all three groups. In four of five characters the cliff- erences are only comparative and do not indicate a clear cut distinction; only in the fifth does Cophosaurus show a real distinctness.

An alternate interpretation of these date would have to con- clude that there is not enough difference to warrant generic status for Cophosaurus, indeed there may not be enough difference to warrant generic status for Holbrookia. The variations described are of the kind and magnitude used in the descriptions of species. Clarke (1965) 100 stated that the push-up pattern is the most distinct feature of

Cophosaurus. Carpenter (1963, 1967) described the same behavior for

Uma, indicating that a genus is capable of supporting greater variation than Clarke has allowed for in Callisaurus, Cophosaurus or Holbrookia.

Guttman (1970b) also commented on Clarke's study, stating:

"A comparison of Callisaurus, Cophosaurus, and Holbrookia (Clarke 1965) indicated the great similarity among these genera. According to Clarke, the uniqueness of Cophosaurus is most clearly shown by its distinctive push-up patt,~rn. A comparison of the display-action patterns of two species of Urosaurus (Carpenter, 1962) or three species of Uma (Carpenter, 1963) indicated to this writer that sufficient intra.generic variation exists to refrain from establishing a genus based on this display pattern."

Guttman was reporting his ele,.'.trophoretic study of sand lizards, in which he analyzed the ~emoglobin components and found that they were all identical. This is highly unusual, especially for different genera. Electrophoretic techniques have been of value in confirming taxo:•.omic relationships. This has been demonstrated by Dessaur et al.

(1962), Dessauer (1966), Gorman and Dessauer (1965), Gorman (1966),

Maldonado and Ortez (1966), and Gut 1:man (1970a and b). The c-:-nclusion

Guttman (1970b) came to, and which supports my conclusions, was that

1:he sand l-i zards are more closely r0lated than their present ta.xonomic status indic 01Les.

Simpson (1%5) states:

"What is deplorable in splitting, is the t,~ndency to raise the ranks of groups without need, that is, without gaining any practical adv.:.ntage. One of the more evident symptoms of this tendency is the appearance of many monot.ypic groups in classific,c;t.ion. ''

The proposal r':!su.lting from this study and date examined fro:r. 0ther studies would elir.:i-'. 11.ate one monotypic genera, plus it would give a 101 better indication of close relationships that are so evident in the sand lizards.

Axtell (l958) believed that the sand lizards evolved under subhumid conditions, not greatly different to the conditions exist- ing today in the sand lizard range. He postulates that it was during the Mid-Pliocene that Holbrookia developed the covered tympanum. He then stated, "The species previously known as Holbrookia texana, but which now appears to belong in the Callisaurus line of evolution has probably developed the covered tympanum independently.'' Axtell' s phylogenetic tree for the sand lizards is presented in Plate 16.

Earl (196la,b,c, and 1962) indicated that Cophosaurus was intermediate between Callisaurus and Holbrookia in ear anatomy, but agreed w;ith Axtell that earlessness evolved twice reporting that related groups have the potentiality to develop identical clines, and under similar environmental conditions these identical clines may develop at different times and places. This concept was discussed by

Maslin (1952), who put forth the idea while discussing morphological criteria of phyletic relationships. Norris (1958) and Clarke (1965) also agreed with Axtell in the idea of separate earless evolution.

The concept of two evolutions for earlessness may be a major barrier to the understanding of sand lizard relationships. Since we lack a fossil record of sand lizards, there is no way of knowing when or how such a character came about. It has been suggested (earl 1961a) that it crune about in response to the burrowing habit, but this is purely speculative as there are many burrowing species that do not have a covered tympanwn, including Uma. A covered tympanum is not unique to "sand lizards", the agamid genus Tympanocryptis in Australia 102

is earless, so are some of the members of Phrynocephalus and Phrynosoma both have eared and earless members. Norris' (1958) idea is acceptable

that Callisaurus and Holbrookia split in the early~Pliocene, with

Holbrookia occupying the table lands of the Mesa of Central Mexico, and Callisaurus, having been isolated from Holbrookia before their radiation to the northern habitat. The habitats of the Chihuahuan desert and Sonoran desert are similar, thus the draconoides and texanus groups would have had an excellent opportunity to parallel each other

sufficiently to account for the external morphologic similarities.

Internal structures are not as accessible to external selective pressures and may then indicate more accurately the true relationships; namely, that the texanus group is more closely related to Holbrookia

than to Callisaurus which it resembles through parallelism.

That earlessness may have evolved twice is possible, and it

is most probable that there were separate evolutions for this character

in the genera T)7E1panocryptis, Phrynocephalus, Phrynosoma, and sand lizards. To theorize that it evolved twice in the sand lizards, is however, a questionable concept. Earless sand lizards are closely related, their geographic ranges overlap, their habitats are similar,

their food requirements similar, similar, the ear anatomy similar, and we lack any evidence from fossil records that they diverged before the earless character arose. Where evidence indicates a close taxonomic relationship, as it does here, the idea of a single evolution for the

earless character is most plausible. It is very unlikely that the same character would evolve twice in the same way in two groups that are as closely related as earless sand lizards. (A proposed phylogenetic tree :is given in Plate 17 .) 103

This data, when added to that of earlier workers, see,--:is to clearly indicate that sand lizards may best be represented by three genera, Um~, Callisaurus, as at present constituted, and Holbrookia, which includes COJ2fl0S aurus as Baird and Girard set it up in 1852.

Characters that separate sand lizard into genera are fer.-, and not well defined, when co:npared to distinctions behre~n other Scelop- l orin2 genera. The relation3hip between Callisain:us and Holb-r-ookia is especially close, with earlessness and body proportions being tne most striking variants. Uma, on the other hand~ appears to be well defined. It is felt that Holbrookia is, therefore a recent derivitive of Callisaurus, evolving earlessness and a toleration for varied habitats in a relatively short time, perhaps since their separation in the late Pliocene.

Sand lizards, particularly the species and subspecies of

Holbrookia, still appear to be in process of rapid geographical differentiation. Large number of similar subspecies, part:icularly in H. maculata, indicates that this group has recently undergone adaptive radiation. If recent geological past has been correctly interpreted by recent paleontological findings (Etheridge, 1961, and

Wells and Jorgensen, 1964), the desert areas of today, exten::ing from Texas to California were very different as recently as 10,000 years ago, indicating that sand lizard adaptations must be re.latively recent.

Evidence fron internal morphology and geographical distribution indicates that earless sand lizards should remain as two closely related groups in the genus Holbrookia. Data from comparative skull and throat anatomy, if used alone, indicates a very close relationship 104 between Callisaurus and Holbro~kia but it is felt that the distinctions, however slight, do indicate that Holbrookia has evolved from

Callisaurus and has achieved sufficient distinctness to be given generic status. It is, therefore, proposed that sand lizards be classified as th2y were before Cophosaurus was split off by Clarke

(1965). This is as follows:

Uma notata Bai.rd Uma ~coparia Cope Urr..a exsul Schmidt Umc1:paraphygas Williams, Chrapling, and Smith Callisaurus draconoides Blainville Ho1.brookia texana Troschell Holbrookia lacerata Cupe Holbrookia macu1ata Girard Holbrookia v:opinqua Baird s.nd Girard 105

Plate· 16. Phylogeny of the sand lizards according to Axtell (1958). 106

DIR ECTIO 1'-1 OF SPECIALIZATION < :,..

0 :, .. D .,. .. 0 ! 0 C ~ C II ! II .. :, - 0 0 :, .. .. 0 C .. 0 .. 0 "0 .. -0 II " E C .. - ..II -0

CAL LI SAUR.US

TYMPANUM TYMPANUM EXPOSED COV~Ri:D

SAND LI.ZARO PROGENITOR 107

Plate 17. Proposed Phylogeny of the Sand Lizards

- 108

< DIRECTION OF SPECIALIZATION .. > 0 0 .. ! :, "'O C ! ! 0 0 .,. 0 .. ..'! C C .. u 0 i.. i 0 0 .. - ..

CALLISAURUS

TYMPANUM TYMPANUM EX POSED > COVERED

SANO LIZARD PROGENITOR LITERATURECITED

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CALLISAURUS, COPHOSAURUS, HOLBROOKIA, AND __UMA , THE "SAND LIZARDS"

Douglas Charles Cox

Department of Zoology

Ph.D. Degree, December 1976

ABSTRACT

A detailed study of the anterior osteology and myology of Callisaurus, Cophosaurus, Holbrookia, and Uma reveals the phylogenetic relationships among the sand lizards. An SPSS dis criminant analysis of osteological characters combined with myological characters indicates that Callisaurus is most primitive, Cophosaurus and Holbrookia are most closely related, and Uma is the most distinct of the sand lizard genera. Because of close relationships between Copnosaurus and Holbrookia it is postulated that earlessness evolved once and Cophosauru� is restorec1 to species status in Holbrookia as Holbrookia texana •