Osteological and Mylogical Comparisons of the Head and Thorax

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Brigham Young University Science Bulletin, Biological Series

Volume 11 | Number 1 Article 1

6-1970 Osteological and mylogical comparisons of the head and thorax regions of Cnemidophorus tigris septentrionalis Burger and Ameiva undulata parva Barbour and Nobel (Family Teiidae) Don Lowell Fisher

Wilmer W. Tanner

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Recommended Citation Fisher, Don Lowell and Tanner, Wilmer W. (1970) "Osteological and mylogical comparisons of the head and thorax regions of Cnemidophorus tigris septentrionalis Burger and Ameiva undulata parva Barbour and Nobel (Family Teiidae)," Brigham Young University Science Bulletin, Biological Series: Vol. 11 : No. 1 , Article 1. Available at: https://scholarsarchive.byu.edu/byuscib/vol11/iss1/1

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^ AUG 1 8 1970 HARVARD UISUVERSITYi Brigham Young UniversWy

Science Bulletin

OSTEOLOGICAL AND MYLOGICAL COMPARISONS OF THE HEAD AND THORAX REGIONS OF CNEM/DOPHORUS TIGRIS SEPTENTRIONALIS BURGER AND AMEIVA UNDULATA PARVA BARBOUR AND NOBLE

(FAMILY TEIIDAE)

'^ Don Lowell Fisher and Wilmer W. Tanner ^

BIOLOGICAL SERIES — VOLUME XI, NUMBER 1

JUNE 1970 BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN BIOLOGICAL SERIES

Editor: Stanley L. Welsh, Department of Botany, Brigham Young University, Provo, Utah

Members of the Editorial Board:

Stanley L. Welsh, Chairman of the Board

Tipton, Veknon J. Zoology Febbon L. Anderson, Zoology

Beck, Microbiology J. V. Joseph R. Muedock, Botany Wilmer W. Tanner, Zoology

Ex officio Members:

A. LesterLes' Allen, Dean, College of Biological and Agricultural SciencesSci

Ernest L. Olson, Chairman, University Pubhcations

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OSTEOLOGICAL AND MYLOGICAL COMPARISONS OF THE HEAD AND THORAX REGIONS OF CNEMIDOPHORUS TIGRIS SEPTENTRIONALIS BURGER AND AMEIVA UNDULATA PARVA BARBOUR AND NOBLE (FAMILY TEIIDAE)

Don Lowell Fisher and Wilmer W. Tanner

BIOLOGICAL SERIES — VOLUME XI, NUMBER 1 JUNE 1970 .

TABLE OF CONTENTS

Page

INTRODUCTION 1 METHODS AND MATERIALS 2 OSTEOLOGY 3

General Description of the Si

Description of Skull Elements 4 Lower Jaw '3

Foramina of the Skull and Lower Jaw 16 Teeth 17

Wrist 19 MYOLOGY 19 DISCUSSION 30 CONCLUSIONS AND SUMMARY 37 LITERATURE CITED 39

LIST OF ILLUSTRATIONS

Figure Page

1 Ameiva undulata pan'a. Dorsal view of skull (6.2X) 5

2. Ameiva undulata pan'a. Ventral view of skull (6.2X) 6

3. Ameiva undulata panm. Lateral view of skull. (6.2X) 7

4. Cnemidohponis tigris septentrionalis. Dorsal view of skull. (8.4X) 8

5. Cnemidophoms tigris septentrionalis. Ventral view of skull. (8.4X) 9

6. Cnemidophoms tigris septentrionalis. Lateral view of skull. (8.4X) 10

7. Ameiva undulata parva. Lower Jaw. A. Lateral view. B. Medial view. C. Dorsal view. (4.9X) teeth diagramatic, see Fig. 9 14

8. Cnemidophoms tigris septentrionalis. Lower Jaw. A. Lateral view. B. Medial view. C. Dorsal view. (7.5X) teeth diagramatic, see Fig. 9 15

9. Ameiva undulata pan'a. Teeth. A. Maxillary teeth. (7 .OX). B. Dentary teeth. (5.8X). Cnemidophoms tigris septentrionalis C. Maxillary teeth. (II.OX). D. Dentary teeth. (9.7X). E. Pterygoid teeth. (20X) 18

10. Ameiva undulata pan'a. Musculature dorsal view. A. Superficial depth. B. First depth. (2.9X) 20

11. Ameiva undulata pan'a. Musculature dorsal view. A. Second depth. B. Third depth. (2.9X) 21

12. Ameiva undulata pan'a. Musculature dorsal view. A. Fourth Depth. B. Fifth depth. (2.9X) 22

13. Ameiva undulata parva. Musculature ventral view. A. Superficial depth. B. First depth. (2.9X) 23 14. Ameiva undulata parva. Musculature ventral view. A. Second depth. B. Third depth. (2.9 X) 24

15. Ameiva undulata pan'a. Musculature ventral view. A. Fourth depth. B. Fifth depth. (2.9X) 25

16. Ameiva undulata parva. Musculature lateral view. First depth. (2.9X) 26

17. Ameiva undulata parva. Musculature lateral view. Second depth. (2.9X) 27

18. Ameiva undulata pan'a. Musculature lateral view. Third depth. (2.9X) 28

19. Ameiva undulata parva. Musculature latural view. Fourth depth. (2.9X) 29

20. Ameiva undulata pan'a. Musculature lateral view. Fifth depth. (2.9X) 30 ,

INTRODUCTION

There has long been a need for a comparative on the Pacific slopes from the Isthmus of Tehaun- study of the osteological and myological structures of tepec in Oaxaca south to Costa Rica.

the reptilian family Teiidae. This present study is Cnemidophonis tigris septentrionalis was estab-

organized to increase our understanding of the ana- lished by Burger in 1950. The type is CNHM 38217 tomical features of the head and thorax regions of and the type locality is Una, Garfield County, Colo- two large genera of this large and diversified family. rado. The range extends over the Colorado Plateau The two genera discussed are Cnemidophonis and (Maslin, 1959b) and includes the northern half of A meiva. Arizona, the northwestern quarter of New Mexico,

Although the entire family is in need of a compar- the southeastern half of Utah, and the southwestern ative study, these two genera were chosen because quarter of Colorado (Burger, 1950). they are, according to Burt (1931b), closely allied A synopsis of the genus Cnemidophonis was first and also because a number of study specimens were completed by E.D. Cope (1892b) wherein he made a available. The study is limited to the head and thora.x most memorable statement to all individuals who regions inasmuch as this area, according to Patten further attempt to resolve the phylogenetic relation- (1951), seems to be the most plastic region of the ships within this genus. He considered the discrimina- body as far as adaptive radiation is concerned. We are tion of the species within Cnemidophonis the most aware that other regions of the vertebrate body are difficult problem in herpetology. also plastic in some groups; however, we believe that A later work by Burt (1931b) using Ecology, in this family the thorax region is of special signifi- scutellation, and distribution has helped in unrav- cance to the study of the phylogenetic development elling some of the problems of the phylogenetic of genera within this family. relationships within the genus Cnemidophonis. Other Studies dealing with taxonomy, physiology, ecol- large and comprehensive works on groups within the ogy and general anatomy of the two genera have been genus Cnemidophonis also have been recently com- made by various workers. Those reports which are pleted. These include a report by Zweifel (1959) on pertinent to this study are cited below. the distribution and variation of the sacki group, a An extensive taxonomic study of the genus systematic study of the deppei group (Duellman and Cnemidophonis was made by Burt (1931b) with com- Wellman, 1960), and a systematic study of the plete synonymy of the various species and subspecies sexlineatus group (Duellman and Zweifel, 1962). to that date. A revision of the g^nus Ameiva was com- These works all analyze such characters as scutella- pleted by Barbour and Noble (1915). Smith and tion, coloration, dorsal patterns, size, and distri- Laufe (1946) in their summary of the Mexican lizards bution. of the genus A meiva dealt with the taxonomy of the The systematic relationships of the gtnns Ameiva

genus. It will not be necessary, therefore, to give a have also been explored by Barbour and Noble detailed account in this report of the taxonomy (1915), who published an extensive work on the which has been completed to date. We can thus phylogeny and provided a description of the species confine ourselves more to the comparative anatomical and subspecies included in the genus. The relation- aspects of the two genera. ships of the Ameiva undiilata group were suggested The family Teiidae was established by Gray by Stuart (1942). In this study he includes a diagnosis (1825), and today consists of about 40 genera (Smith of each species as well as a key to the species. and Taylor, 1950). The genus /l/?!e(Va was established A summary of the Mexican species of the genus by Meyer (1795) with Lacerta americana Seba = Ameiva was published by Smith and Laufe (1946). Ameiva ameiva (Linnaeus) being the genotype. Ac- Their report is informative, extensive, includes a his- cording to Smith and Taylor (1950), there are 13 torical summary and an analysis of characters by species and 28 subspecies in the genus. means of scutellation. A phylogeny, a key to the The genus Cnemidophonis was established by Mexican Ameiva, and an account of the subspecies is

Wagler (1830). The genotype is Seps murimis also included. Laurenti. There are about 18 species of Cnemi- Some of the factors relating to behavior and evolu- dophorus with about 47 subspecies (Smith and tion have also been reported. A thorough study for its Taylor, 1950). Since 1950 only a few new species and time by Gadow (1906) on evolution was based on the subspecies have been described in each genus. Mexican species of Cnemidophonis. His report helps Ameiva undiilata parva was established by Barbour us to realize the great variety possible in a genus

and Noble (1915). The type is MCZ 5831 (with Van which has evolved in a land filled with the diversity of

Patten as the collector) and the type locality is listed bionomic conditions found in Mexico. Other studies as Guatemala; however, this was later restricted by include those by Broom (1925), Maslin (1959a, 1961

Smith and Laufe (1946) to Mazatenango. The range is 1966), Zweifel (1962), Beargie and McCoy (1964),

1 BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN

Pennock (1965), Licht (1966), Lowe and Goldberg (1960) presented the tooth replacement phenomena (1966), McCoy (1966), and Taylor and Medica in lower vertebrates. (1966). The myology of the family Teiidae has been Much of the literature available on the family studied only to a limited extent. Camp (1923) and Teiidae deals with old and new collecting localities Poglayen-Neuwall (1954) included work on Tupinam- and taxonomy. Some such papers are those by Gray bis, with a few references to the deep skull muscul-

(1825), Boulenger (1884, 1899), Nopcsa ( 1928), Burt ature oi Ameiva. No comparative or descriptive study (1929, 1931a, 1931c), Beebe (1945), Smith and of the myology of Cnemidophorus or Ameiva has yet Burger (1949), Burger (1950), Smith and Taylor appeared. Perhaps the most extensive treatment of

(1950), Maslin, Beidleman and Lowe (1958), Maslin vertebrate cranial muscles is the work of Edgeworth (1963), Peters (1964), Zweifel (1965), and Stebbins (1935).

(1966). The position of the family Teiidae is unique in its Fossil teeids have been reported by Brattstrom phylogeny among the other saurians. This was ob- (1954), Etheridge (I960). Gehlbach (1965), and served by Stokely (1950) in his report on the occur- Romer(1966). ence of an intermedium in certain lizards. He found A number of anatomical works are of importance the intermedium present in several species of Cnemi- to those working in herpetology in the areas of oste- dophonis, but absent in Ameiva ameiva praesignis. ology and myology. Among these are Boulenger Camp (1923) considered the presence of this wrist (1891), Cope (1892a), Howes (1902), Bradley bone an indication of an older position in phylogeny. (1903), Broom (1903), Huntington (1903), Kingsley The apparent differences within the family Teiidae on (1905), Kesteven (1919), Camp (1923), Reese this structure warrant a more detailed investigation. (1923), Romer (1924), Sinsitsin (1928), Edgeworth There is reason to believe that further osteological (1931), Broom (1935), Davis (1936), Howell (1936), and myological studies of the family Teiidae should Gnanamuthu (1937), Dubois (1942, 1943), George include comparisons with members of the family (1948), Adams (1953), Poglayen-Neuwall (1954), Lacertidae. The work of Uzzell (1959) and others Snyder (1954), Oelrich (1956), Romer (1956), Hofer suggest a parallelism that may be fruitful in (I960), Jollie (1960), Robison and Tanner (1962), phylogeny as well as anatomy.

Avery and Tanner (1964), and Romer (1964, 1966). The purpose of this paper, therefore, is to present Althougli most of the anatomical works men- a report on the anterior osteology and myology of a tioned above do not consider extensively the family species of the genus Ameiva and to compare it with a Teiidae, some are of special importance to a study of species of the closely allied genus Cnemidophorus. It this family. Camp (1923) compares anatomically the may thereby be possible to develop other criteria to families of reptiles and emphasized the genus be used in determining the phylogenetic relationships Tupinambis as a member of the family Teiidae. Two between Cnemidophorus and Ameiva within the other works of osteological import for the genus family Teiidae. Tupinambis are those by Reese (1923) and Hofer We are grateful to Dr. Bertrand F. Harrison for his (I960). To date, only one work has been published suggestions in preparing the manuscript and to Mr. on the complete cranial osteology oi Cnemidophorus, Lee F. Braithwaite for his aid in the preparation of on C. sexlineatus and C. giilaris by Dubois (1943). A the illustrations. Dr. Robert T. Swenson and the major osteological report on Ameiva has not appeared X-ray technicians at the Utah Valley Hospital pre- to date. Taylor (1940) was one of the first to estab- pared the X-ray photographs of the wrist elements. lish the presence of pterygoid teeth in Cnemi- We extend our thanks to the above and others who dophonis. His study included nine species. Edmunds have aided us in this project.

MATERIALS AND METHODS The specimens of C. t. septentrionalis were collected from southeastern Utah. Five came from

Cnemidophorus tigris septentrionalis Burger and North Wash near Hog Spring (BYU 31903-07); two Ameiva undulata parva Barbour and Noble are the from Star Spring (BYU 31908-09); one from Bullfrog principal species and subspecies used in this study. In Basin (BYU 31910); three from North Wash along

the body of the text they will be designated as C. t. highway U95 between Star Spring and Hanksville

septentrionalis and A. u. parva respectively. Speci- (BYU 31911-13) and nine from Snow's Canyon, west mens of Cnemidophorus tigris tigris Baird and Girard of Saint George, Utah (BYU 31914-22).

and Cnemidophorus tigris gracilis Biard and Girard The specimens of C. t. tigris were collected in were also dissected for comparative purposes. western Utah. Six specimens came from Lake Moun- BIOLOGICAL SERIES. VOL. 1 1 , NO. 1 OSTEOLOGICAL AND MYLOGICAL COMPARISONS

tain west of Utah Lake (BYU 31923-28), and one in pencil using a micrometer eyepiece for exactness. from Milford, Utah (BYU 3 1929). The drawings were then enlarged by use of an opaque

The specimens of C. t. gracilis Baird and Girard projector and inked using a L 4 Koh-I-Noor drawing examined were taken 1 1 miles east of Bowie, Cochise pen. Stippling and line-shading methods described by Co., Airzona (BYU 13555-61). Zweifel (1965) were adopted, using a #00 A. u. parva were collected at Finca Tinajas, Koh-I-Noor drawing pen. Lettering was made with Panzos, Alta Verapaz, Guatemala (BYU 14389, Prestype futura demi 18 and 36 point. 14895-96, 14398, 14444, 14448-51, and 14453). Photographs of all work accomplished were made The specimens used for X-ray analysis of the wrist for comparison purposes using an Exacta camera with elements were the following: C. t. septenthonalis an f22 aperture at 1/25 of a second and a double rings used to (BYU 31904); C. t. gracilis (BYU 13560); C. t. caniis flash attachment. Expansion were

VanDenburgh and Slevin (BYU 301 59); C. t. aethiops obtain a 4;1 ratio enlargement. Kodak plus-X ASA

Cope (BYU 30196); C. t. tigris Baird and Girard 1 25 pan film was used.

(BYU 30552); C s. communus Cope (BYU 24017);

C. s. gularis Baird and Girard (BYU 12876); C. d. deppei Wiegmann (BYU 22541); C. /. lineatissisimus OSTEOLOGY

Cope (BYU 24018); C. /. lemniscatus (Linnaeus)

(BYU 22599); C. exsanguis Lowe (BYU 14158);/4. ;/. An extensive study of all the skeletal elements of Iiartwegi Smith (BYU 22523); A. u. sinistra Smith the body is not the primary purpose of this report. and Laufe (BYU 24013); A. u. parva (BYU 14398) The discussion, therefore, is limited to the skull, wrist and A. auberi Cocteau (BYU 30326). bones, and a comparison of the teeth. In each case, a Radiographs were taken with an X-ray machine full description oi A. u. parva is given under each ele- using eleven milliamps at one and one-half seconds ment using two skulls to determine all structures and with a medium KVP. X-ray negatives were then en- listed as "^4". This is followed by only the com- larged in a slide projector and examined. parative differences noted in skulls of C. t. septentri- Skulls were cleaned by various methods. One onalis under each element and listed as "C". Two

specimen of A. u. parva (BYU 144451, snout-vent skulls each of C. t. tigris and C. t. gracilis were also length 100 mm.) was skinned and placed in 35 per- examined for comparative purposes. If not otherwise cent ammonium hydroxide for two months, boiled stated, items not listed in "C" are essentially the same

for two hours and then cleaned by hand. It was then as those in "/I". treated with Clorox bleach at full strength for 15 minutes with excellent results. Another specimen of General Description of the Skull

A. u. parva (BYU 14450, snout-vent 86 mm.) as well

as two C. t. septentrionalis (BYU 31924 and 31926, A. Generally, the skull can be considered heavily

snout-vent length both 84 mm), and two C. t. gracilis ossified for members of the family Teiidae having the (BYU 13559 and 13561, snout-vent length 70 and 71 dorsal surface rather rugose with prominent indenta- mm. respectively) were skinned, hand cleaned of tions present indicating positioning of overlying muscle tissue and then boiled for two hours. The scutellation. Prominent dorsolateral orbital fenestrae skulls were then soaked in Clorox bleach at full dominate the middle portion of the skull. Posteriorly, strength for 35 minutes with adequate results. Care two prominent fenestrae are present: a posterodorsal must be taken not to leave a skull too long in the supratemporal fenestra and a posteroventral infra- bleach solution. If not properly attended, temporal fenestra separated by a temporal arch com- disarticulation occurs after a certain length of time posed of the fused postorbital-postfrontal and the depending on the size and thickness of the skull squamosal bones. Such a condition is termed diapsid

bones. and is typeical of the condition seen in the fossil

Myological studies were made on C. t. septentrion- ancestors of modern lizards (Romer, 1966). alis (BYU 31906-8, 31910, 31024 and 31925 with The foramina of the ventral surface anteriorly are snouth-vent lengths of 77, 84, 74, 92, 84 mm. re- those for the vomeronasal organs of Jacobson fol-

spectively) and A. u. parva (BYU 14396, 14444, lowed by the elongate internal nares. The floor of the 14448-9 and 14453 with snout-vent lengths of 111, orbit in the central portion of the skull is opened by 108, 91, 75, and 127 mm. respectively). All the infraorbital foramen. specimens were carefully skinned and muscles The occipital portion of the skull forms a posterior dissected using small pieces of a new razor blade held union for dorsal and ventral segments to enclose the securely in an x-acto knife handle. All specimens brain. The occipital bones are highly fused and rel- studied had been preserved in 10 percent formalin. atively difficult to differentiate. The brain case is

All drawings were made on Clearprint "fade-out" composed of ventral projections of the parietal, paper. The specimens were examined under a anterior projections of the supraoccipital, exoccipital, 10X-40X binocular dissecting scope and then drawn and the basioccipital. The foramen magnum poster- BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN

ocentrally is bordered by the supraoccipital dorsally, A. Posteriorly, it articulates with the anterolateral the basioccipital ventrally and the exoccipitals later- projection of the pterygoids. A prominent ectop- ally. The occipital condyle is tripartite and is located terygoid process is noted as a ventral projection. Lat- on the posterior end of the basioccipital and the erally, articulation is with the maxilla, jugal, and medioventral projections of the exoccipitals. pterygoids, but a complete separation of jugal from The large quadrate bones of the posterolateral the pterygoid or separation of maxilla from the jugal portion of the ventral surface are loosely attached to is made. Anteriorly, articulation is with the palatine the occipital processes and thus appear to allow for bones. The medial border forms the lateral margin of greater expansion of the lower jaw. the infraorbital foramen. Dorsally, it forms the

C. Generally, the skull is ligliter, that is the bones posterolateral floor of the orbit. are thinner and the dorsal surface is relatively gla- C. The ectopterygoid process is pronounced and a brous. There is little indication of indentations for separation of it from the pterygoid is complete, thus scutellation on the dorsal surface. The anteromedial forming a small anterior border of the infratemporal border of the orbit is cartilaginous and the occipital fenestra.

skull is not higlily fused, permitting portion of the Epipterygoid.— paired bones (Fig. 3 and 6) most elements to be more easily distinguished. A. This pillar-shaped bone forms the anterolateral More specifically, the differences between the two wall of the brain case. Articulation is with the genera are considered with each of the individual pterygoid ventrally by means of a small depression skull elements. and dorsally with an anteroventral projection of the

parietal. A prominent lateral ridge is visible for its entire length. Description of Skull Elements C. Relatively little difference is noted.

All elements, for the sake of clarity, are discussed Exoccipital. -paired bones (Fig. 1, 2, 3, 4, 5, and 6) in alphabetical order. Only bones are paired are which A. The limits of this bone are difficult to deter- indicated as such. mine as there has been an extensive amount of fusion. Articulation sutures with the opisthotic were not Basioccipital. (Fig. 2, 3, 5, and 6) located. The opisthotic, therefore, has been included is partially fused into the occipital A. This bone in this description. Jollie (1960) concurred that su- complex. It forms the posteroventral border of the tures were not observable and Dubois (1943) called a articulate foramen magnum and extends anteriorly to part of this bone the otoccipital in Cnemidophoms. with the basisphenoid. It is bounded laterally by the An extreme posterior projection of the exoccipital exoccipitals and forms the floor of the brain case forms the lateral portion of the occipital condyle. having fused anterolatterally with a pair of processes Medially, it forms the posterolateral wall of the brain Posteriorly, of strongly from the basisphenoid. a pair case. A large posterolateral paroccipital process ex- developed basioccipital tuberosities can be seen which tends to articulate with the tabular, parietal and extend ventrally and slightly laterally. A slight quadrate. Ventral to the paroccipital process a por- median ridge extends along the suture line between tion of the membranous labyrinth is housed. The the basioccipital and the exoccipitals. sutures separating the exoccipital from the prootic C. The bone is thin on the ventral surface and the are not definite, but appear to be along the anterior suture lines between it and the exoccipital are prom- margin of the paroccipital process. No young spec- inent. imens were available in the collection to determine if

this is but a function of age. The suture for articula-

Basisphenoid. (fig. 2, 3, 5, and 6) tion with the supraoccipital is lightly marked by a A. This is the main bone of the floor of the posterodorsolateral ridge extending from the foramen cranium. It is bordered posteriorly by the basiocci- magnum anteriorly to the base of the parietal. Several pital and anteriorly forms a forward projection which formaina can also be noted on the posterolateral walls proceeds along the base of the brain called the rostral which include the foramen rotundum, two small parasphenoid which we considered a separate ele- hypoglossal foramina and the posterior border of the ment. Ventrally, articulation is with the pterygoid fenesta ovalis. bone by means of two ventral foot-shaped basi- C. The paroccipital process articulates by means pterygoid processes. Lateral extensions form an irreg- of a small cartilaginous projection with the post- ular suture with the basioccipitals. The dorsomedial eromedial portion of the squamosal bone as well as portion forms the sella turcica. articulating with the tabular, parietal, and quadrate. C. Relatively little difference is noted. The suture lines for articulation with both the prootic and the supraoccipital bones are more distinct. The

Ectopterygoid. -paired bones (Fig. 1, 2, 3, 4, 5, and ridges denoting position of the semicircular canals are 6) not as definite. BIOLOGICAL SERIES. VOL. 1 1 , NO. 1 OSTEOLOGICAL AND MYLOGICAL COMPARISONS

PM. SM. EXN N.

Skull Bones PAL Palatine Foramina of the Skull BO Basioccipital PAR Parietal BS Basisphenoid PF Prefrontal EXN External nares EC Ectopterygoid PM Premaxilla IN Internal nares Infraorbital foramen EO Exoccipital PO.-POF. . Postorbital-postfrontal lOF EP Epipterygoid PR Prootic ITF Infratemporal fenestra FR Frontal PT Pterygoid NF Nasal foramen JU Jugal QU Quadrate OR Orbital fenestra LA Lacrimal RPS Rostral Parasphenoid SLF Supralabial foramen M Maxilla S Squamosal STF Supratemporal fenestra N Nasal SM Septomaxilla VOJ Vomero-nasal organs of OSP Os Palpabrae VO Vomer Jacobson foramen

Fig. 1. Ameiva undulata parva. Dorsal view of skull. (6.2X) BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN

PM,

Skull Bones PAL Palatine Foramina of the Skull PAR Parietal BO Basioccipital PF Prefrontal EXN External nares BS Basisphenoid PM Premaxilla IN Internal nares

EC Ectopterygoid PO.-POF. . Postorbital-postfrontal lOF Infraorbital foramen EO Exoccipital PR Prootic ITF Infratemporal fenestra EP Epipterygoid PT Pterygoid NF Nasal foramen FR Frontal QU Quadrate OR Orbital fenestra JU Jugal RPS Rostral parasphenoid SLF Supralabial foramen LA Lacrimal S Squamosal STF Supratemporal fenestra M Maxilla SM Septomaxilla VOJ Vomero-nasal organs of N Nasal VO Vomer Jacobson foramen OSP Os Palpabrae

Fig. 2. Ameiva iindiilata parva. Ventral view of skull. (6.2X) MYLOGICAL COMPARISONS BIOLOGICAL SERIES. VOL. 1 1, NO. I OSTEOLOGICAL AND

Foramina of the Skull Skull Bones PAL Palatine PAR Parietal External nares Basioccipital PF Prefrontal EXN BO Internal nares BS Basisphenoid PM Premaxilla IN Postorbital-postfrontal lOF Infraorbital foramen EC Ectopterygoid PO.-POF. . ITF Infratemporal fenestra EO Exoccipital PR Prootic Nasal foramen EP Epipterygoid PT Pterygoid NF Orbital fenestra FR Frontal QU Quadrate OR SLF Supralabial foramen JU Jugal RPS Rostral parasphenoid STF Supratemporal fenestra LA Lacrimal S Squamosal VOJ Vomero-nasal organs of M Maxilla SM Septomaxilla Jacobson foramen N Nasal VO Vomer OSP Os Palpabrae

of skull. (6. 2X) Fig. 3. /4me!Va i(/7rfw/ara pane Lateral view BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN

Skull Bones PAL Palatine Foramina of the Skull PAR Parietal BO Basioccipital PF Prefrontal EXN External nares BS Basisphenoid PM Premaxilla IN Internal nares EC Ectopterygoid PO.-POF. . Postorbital-postfrontal lOF Infraorbital foramen EO Exoccipital PR Prootic ITF Infratemporal fenestra EP Epiptsrygoid PT Pterygoid NF Nasal foramen FR Frontal QU Quadrate OR Orbital fenestra JU Jugal RPS Rostral parasphenoid SLF Supralabial foramen LA Lacrimal S Squamosal STF Supratemporal fenestra M Maxilla SM Septomaxilla VOJ Vomero-nasal organs of N Nasal VO Vomer Jacobson foramen OSP Os Palpabrae

Fig. 4. Cnemidophorus tigris septentrionalis. Dorsal view of skull. (8.4X) BIOLOGICAL SERIES. VOL. 11, NO. 1 OSTEOLOGICAL AND MYLOGICAL COMPARISONS

POF.

Skull Bones PAL Palatine Foramina of the Skull PAR Parietal BO Basioccipital PF Prefrontal EXN External nares BS Basisphenoid PM Premaxilla IN Internal nares EC Ectopterygoid PO.-POF. . Postorbital-postfrontal lOF Infraorbital foramen EO Exoccipital PR Prootic ITF Infratemporal fenestra EP Epipterygoid PT Pterygoid NF Nasal foramen FR Frontal QU Quadrate OR Orbital fenestra JU Jugal RPS Rostral parasphenoid SLF Supralabial foramen LA Lacrimal S Squamosal STF Supratemporal fenestra M Maxilla SM Septomaxilla VOJ Vomero-nasal organs of N Nasal VO Vomer Jacobson foramen OSP Os Palpabrae

Fig. 5. Cnemidophorus tigris septentrionalis. Ventral view of skull. (8.4X) BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN PM.

Skull Bones PAL Palatine Foramina of the Skull PAR Parietal BO Basioccipital PF Prefrontal EXN External nares BS Basisphenoid PM Premaxilla IN Internal nares EC Ectopterygoid PO.-POF. . Postorbital-postfrontal lOF Infraorbital foramen EO Exoccipital PR Prootic ITF Infratemporal fenestra EP Epipterygoid PT Pterygoid NF Nasal foramen FR Frontal QU Quadrate OR Orbital fenestra JU Jugal RPS Rostral parasphenoid SLF Supralabial foramen LA Lacrimal S Squamosal STF Supratemporal fenestra M Maxilla SM Septomaxilla VOJ Vomero-nasal organs of N Nasal VO Vomer Jacobson foramen OSP Os Palpabrae

Fig. 6. Cnemidophorus tigris septentrionalis. Lateral view of skull.(8.4X) BIOLOGICAL SERIES. VOL. , NO. 1 OSTEOLOGICAL AND MYLOGICAL COMPARISONS 11

C. The middle portion is much narrower with the iorly by the posterior projection of the premaxilla. entire infraorbital foramina appearing visible in a Posterolaterally, articulation is with the prefrontal, dorsal view. The ventral portion of the frontal is being separated from it on the extreme posterior deeply grooved, with prominent anterior arches margin by the lateral process of the frontal. Ventrally noted. Of the three anterior processes, the lateral two the dorsal surface of the nasal canal is formed and the are slightly longer than the central median process. dorsal surface is perforated by several irregularly spaced nasal foramina.

Frontal. (Fig. 1 and 3) C. The central union of the two nasals is much

A. The dorsal surface of this bone is very rugose, longer and the nasal foramina seemingly are more possessing deep indentations for overlying scuteila- regularly placed as well as having a larger posterior tion. The posterior margin is buttressed by the border where the external nares are formed. parietal and posterolaterally articulation occurs with the anterior projections of the postorbital-post- Os palpebrae.— paired bones (Fig. 1 and 3) frontal. The ventral surface is convex medially, A. This is a small triangular ossified bone in the tending to flatten posteriorly when seen in cross sec- anterodorsal border of the orbit which articulates tion. When viewed dorsally, the middle portion entirely with the prefrontal. appears to extend laterally to cover the medial C. The OS palpebrae is not present as an ossified borders of the infraorbital foramina. Laterally, the structure. dorsal margin of the orbit is formed. In the anterior aspect, three processes are produced of which the Palatine.— paired bones (Fig. 2 and 5) A. middle is the longest and inserts between the two The palatine articulates posteriorly with the nasal bones. The lateral processes insert between the pterygoid and anteriorly with the ectopterygoid and nasals and the prefrontals. Ventrally, the anterior maxilla. The anterior-most articulation is with the portion is arched into ventral columns to allow vomer and then a central union is formed beneath passage for the olfactory tracts. No pineal foramen is two strong ridges of the primary palate with the other present. palatine. A strongly developed depression marks the

dorsal and lateral surfaces of the nasal canal and internal nares. The medial border of the palatine canal Jugal. -paired bones (Fig. 1 , 2, 3, 4, 5, and 6) A. A long curved bone forming the ventrolateral is also formed. margin of the orbit and the anterior margin of the C. The anterior medial processes are also joined infratemporal fenestra. Articulation posteriorly is beneath two strong ridges of the primary palate con- with the ventral surface of the postorbital-postfrontal trary to the findings of Dubois (1943). and ventrally a small projection articulates with the pterygoid posteriorly and the ectopterygoid anter- Parietal. (Fig. 1,3,4, and 6) iorly. The anterior-most border articulates with the A. The parietal is a rugose bone with deep inden- lacrimal dorsally and the maxilla ventrally. A small tations indicating overlying scutellation and is spur is noted on the posterior margin of its ventral roughly rectangular in shape. Two large posterior pro- surface. jections form the parietal arch and articulates with

C. Ventrally, articulation is completely with the the tabular, squamosal, and the paroccipital processes ectopterygoid and not with a portion of the ptery- of the exoccipital. Anterolaterally, articulation is goid. No spur is noted on the posterior margin of the with tiie postorbital-postfrontal and the remainder of ventral surface. the anterior border buttresses the frontal. Large ventrolateral flanges deflect downward to enclose the Lacrimal.— paired bones (Fig. 3, 4, and 6) posterodorsal portion of the brain and articulate with A. Found in the anteroventral portion of the the supraoccipital, exoccipital, and the epipterygoid. orbit, this bone articulates posteriorly with the jugal, Ventrally, there is no central ridge, but the posterior ventrally with the maxilla and dorsally with the pre- central margin contains a deep indentation which frontal. In the anteromedial aspect the lacrimal duct may hold a remnant of the synotic tectum of the is found, but no part of the palatine canal is formed. chondrocranium.

C The dorsal-most portion of the palatine canal is C. A small median ridge is present on the ventral formed by the lacrimal. aspect of this bone which may partially fill the area of the central fissure of the brain. The dorsal surface

Nasal. -paired bones (Fig. 1,3,4, and 6) is only lightly rugose posteriorly with the anterior A. The nasals form the anterodorsal portion of portion essentially glabrous. the rostrum and enter the extreme posterior border of the external nares. Posteriorly, separation is by the Postorbital-postfrontal.— paired bones (Fig. 1, 2, 3, 4, central process of the frontal. They then meet in the 5 , and 6) center for a short distance only to be separated anter- A. The postorbital and postfrontal of most 12 BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN

saurians appear to have fused into one bone, althougli the positioning of the semicircular canals is more dif- there is a hght fusion line marked on the dorsal ficult to determine because the external ridges are less median surface. This bone divides the orbit from the pronounced in the bone. supratemporal fenestra and also has a posterior projection which forms part of the temporal arch divid- Pterygoid. -paired bones (Fig. 1,2,3, 4, 5, and 6) ing the supratemporal fenestra from the infra- A. A "Y" shaped bone on the ventral surface of temporal fenestra. Dorsally, articulation is anteriorly the skull, the pterygoid articulates posteriorly with with the frontal and posteriorly with the parietal. the quadrate and anteriorly with the palatine medi-

Ventrally, articulation is anteriorly with the jugal and ally and the ectopterygoid laterally The central por- posteriorly with the squamosal. A small flange is tion forms the posterior border of the infraorbital observable in the anterior central position. foramen. Ventrally, articulation is with the basi- C. The postorbital and postfrontal are completely pterygoid process which fits into an oblique groove fused with no evidence of suture lines. No small on the ventral surface; on the dorsal surface directly flange is observable in the anterior central position. opposite the basipterygoid process, the epipterygoid articulates in a small depression. The posteromedial

Prefrontal. -paired bones (Fig. 1, 3, 4, and 6) margin is expanded into a knifelike ridge extending A. The prefrontal lies anterolateral to the frontal horizontally to the posterior end. Teeth are not and articulates with its posterodorsal surface Anter- present on the anteromedial portion. The lateral omedially. articulation is with the nasals and laterally border, along most of its length, forms the medial with the maxilla. Posterodorsally, articulation is with edge of the infratemporal fenestra. The rostral para- the OS palpebrae. A small posteroventral projection sphenoid rises dorsally between the pterygoids. contacts the lacrimal and ventrally this projection C. The anteromedial margin contains five then articulates with the palatine. The posteroventrol- pterygoid teeth. (Dubois, 1943, reported three on the ateral aspect forms a portion of the lacrimal duct. pterygoid of C. sexlineatus.) The posteromedial C. A small posteroventrolateral projection forms margin is less expanded and the central gap between the dorsal portion of the palatine canal. There is no the two pterygoids is wider at the posterior margins. OS palpebrae to articulate with the posterodorsal border. Quadrate. -paired bones (Fig. 1, 2, 3, 4, 5, and 6) A. The quadrate articulates with the articular of

Premaxilla. (Fig. 1 , 2, 3, 4, 5, and 6) the lower jaw. The articulation is on cartilaginous A. The anterior-most bone of the skull, the pre- pads thus allowing for greater jaw expansion. In the maxilla, inserts dorsally between the nasals for a short medial area, articulation is with the pterygoid posteri- distance posteriorly. Medially it is broad and ventrally orly and anteriorly with the squamosal, tabular and articulation is with the vomer and with the maxilla paroccipital process of the exoccipital. The lateral ventrolaterally. The dorsolateral margins form the border is expanded into a slightly recurved tympanic medial border of the external nares and the nasal crest and the medial border also forms a small crest canal. The ventral surface bears 10 peglike pleurodont for loose articulation with the prootic. The union of teeth. the posterior margins of these two crests forms the C. The posterior projection extends a shorter dis- seat of the middle ear. tance between the nasals. On the ventral surface, 8 C. The tympanic crest is not as greatly expanded peglike pleurodont teeth are borne. Medially the bone laterally, but is highly recurved, thus forming an is rather narrow and less massive than in A. anterior tympanic recess.

Prootic. -paired bones (Fig. 3 and 6) Parasphenoid. (Fig. 2, 3, 5, and 6)

A. The position of the prootic is highly indeter- A. This is a long pointed foil-like projection pro- minate since most of the suture lines are indefinite. ceeding anterodorsally from a fused position with the This bone forms part of the posteroventrolateral wall basisphenoid, between the two pterygoids, and rests of the brain case and encloses the area of the anterior beneath the lower surface of the brain. The para- semicircular canal. Posteriorly, the anterior border of sphenoid is considered a separate element from the

the fenestra ovalis is formed and anteroventrally a basisphenoid as its identity has been established well developed ridge then proceeds to the base of the embryologically, structurally, and paleontologically basipterygoid process. Dorsally and anteriorly artic- (Dubois, 1943). ulation is with the parietal and posteriorly with the C. Relatively little difference is noted. supraoccipital and exoccipitals. Ventrally and posteriorly the basioccipital and anteriorly the basisphenoid Septomaxilla. Fig. 3 and 6)

meet. The central portion is dominated by a lateral A. The septomaxilla is a thin plate extending flange anterior to the fenestra ovalis. from the vomer posterolaterally to the ventral margin C. The suture lines are more readily definable, but of the maxilla with a small projection extending BIOLOGICAL SERIES. VOL. 11, NO. 1 OSTEOLOGICAL AND MYLOGICAL COMPARISONS 13 anteriorly into the nasal canal. angular, articular, coronoid, dentary, splenial and

C. Relatively little difference is noted. surangular. The articular makes almost a right angle with the angular, the anterior end of each ramus has a

Squamosal.— paired bones (Fig. 1, 2, 3, 4, 5, and 6) distinct lateral tortion (Fig. 7c), and the ventral sur- A. The squamosal is a relatively simple bone face is rugose. The dentary of each ramus bears a flared posteriorly to articulate with the parietal, tab- single row of pleurodont teeth, whereas the remaining ular, and narrowly with the quadrate. It forms the bones are edentate. The prearticular is fused to the posterior half of the temporal arch separating the articular in the adult and will not by considered in supratemporal fenestra from the infratemporal this report as a separate element of the ramus. fenestra and articulates anteriorly with the postorbit- C. The articular and the angular are essentially in al-postfrontal a straight line. No lateral torsion is seen in the

C. Relatively little difference is noted. anterior end of the ramus (Fig. 8c). The ventral sur-

face of the ramus is essentially glabrous.

Supraoccipital. (Fig. 1 and 4) A. Posteriorly, the supraoccipital forms the dorsal Angular. (Fig. 7 and 8) margin of the foramen magnum and anteriorly artic- A. The angular is positioned at the posteroventral ulates with the parietal. Centrally, a ridge divides the angle of the lower jaw. It articulates at almost right bone into left and riglit halves. The lateral sutures angles dorsomedially with the articular. Dorsolateral with the exoccipital and the prootic are not distinct articulation is with the surangular. The element then except for a small ridge which proceeds anterodors- extends forward where anterolateral articulation is ally from the paroccipital process of the exoccipital with the dentary and anteromedical articulation is dividing the supraoccipital from the prootic. The with the splenial. One small foramen, the angular posterior end of the anterior semicircular canal and foramen, is located on the medial surface. the medial end of the posterior semicircular canal C. The articulation of the angular and the artic- enter anteriorly and unite. ular is essentially a straight line.

C. The central ridge is not sharp,' but the suture lines for the exoccipital and prootic are definable Articular. (Fig. 7 and 8) A. This is the posterior-most bone of the ramus. Tabular. -paired bones (Fig. 1,3,4, and 6) Fusion with the prearticular is so complete that sep- A. Posteriorly, the tabular inserts between the arate elements are not detectable in the adult. The squamosal, quadrate, paroccipital process of the ex- articulating surface for the quadrate on the anter- occipital and the posterior end of the parietal. Anter- odorsal margin is somewhat fused with the surangular iorly, a small projection is sent forward along the so that suture lines are determined only with diffi- ventral margin of the parietal arch for a short dis- culty. The retroarticular process of the posterior edge tance. is winglike and extends medially in the horizontal

C. Relatively little difference is noted. plane. Posteriorly, articulation is with the sur-angular dorsally and the angular ventrally. The element then Prevomer. -paired bones (Fig. 2 and 5) extends forward along the medial surface to meet the A. Medially, the prevomers exist as paired ele- ventromedial surface of the coronoid. There is artic- ments of the central anteroventral surface of the ulation with the extreme posterior extension of the skull, joining the palatine posteriorly and anteriorly dentary and also the splenial. The inner aspect forms the maxilla and premaxilla on the ventral surface and the posteromedial border of the large mandibular the septomaxilla on the dorsal surface. Small foramina foramen. on the anterolateral edge mark the position of the C. The suture line between this bone and the vomeronasal organs of Jacobson and connect them surangular is more distinct. The retroarticular process with the nasal canal. Posterolaterally, the medial extends in a ventrally projecting oblique plane. border of the nasal canal and external nares is formed. A small medial groove beginning centrally Coronoid. (Fig. 7 and 8) and proceeding posteriorly holds the beginning of A. The coronoid is the central bone of the ramus, what appears to be a cartilaginous support for the articulating posteriorly with the articular medially rostral parasphenoid. and the surangular laterally and forming posterocen-

C. Relatively little difference is noted. trally and the anterior border of the mandibular foramen. Anteriorly, articulation is with the splenial Lower Jaw and the dentary. On the medial surface an arch over a small posterior extension of the dentary is formed

A. The lower jaw is united arteriorly by a mental as well as a large coronoid process dorsally. symphysis and posteriorly articulates with the quad- C. The coronoid process is much sharper and rate. Each ramus is composed of six bones: the possesses a small posteriorly directed hook. 14 BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN

AR.

^^°'°«---iinti';TiVftv'i-.-^^^

I i I

I MAP ! I A- SF. SP.

Foramina of the Lower Jaw Lower Jaw Bones

AF Angular foramen A Angular Articular A. Lateral view. MAF Mandibular foramen AR CP Coronoid B. Medial view. MF Mental foramen Dentary C. Dorsal view. SAF Surangural foramen D SF Splenial foramen SA Surangular SP Splenial

Fig. 7. Ameiva undulata parva. Lower Jaw. (4.9X) BIOLOGICAL SERIES. VOL. 1 1 , NO. 1 OSTEOLOGICAL AND MYLOGICAL COMPARISONS 15 CO.

I -di

I I

I MAF. SP. D. Lower Jaw Bones Foramina of the Lower Jaw A Angular AF Angular foramen AR" Articular foramen CP Coronoid A. Lateral view. MAF Mandibular SA Surangular Medial view. MF Mental foramen B. D Dentary C. Dorsal view. SF Splenial foramen SAF Surangular foramen SP Splenial

Fig. 8. Cnemidophonis tigris septentrionalis. Lower Jaw. (7.5X) 16 BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN

Dentary. (Fig. 7 and 8) C. No difference.

A. The dentary is the tooth-bearing bone and comprises the entire anterior half of each ramus. External nares. (Fig. 1 , 3, 4, and 6)

Union is made anteriorly by means of a mandibular A. The external naris is surrounded by the pre-

symphysis with the dentary of the other ramus. Artic- maxilla, nasal, and maxilla and is found at the

ulation is medially with the splenial. dorsally with the anterior end of the rostrum. coronoid. posteriorly with the angular and postero- C. No difference. dorsally by means of a projection with the surangular. A dorsal projection proceeds posteriorly beneath Foramen magnum. (Not Figured)

the anterior process of the coronoid and unites under A. The foramen magnum is the posterior-most

the coronoid arch with the articular. On the dorsal foramen of the skull. It is bounded by the supraoc- surface, there are 23 to 24 pleurodont teeth. Beneath cipital, occipitals, and basioccipital. The lower border the splenial on the medial surface, the Sulcus Carti- forms a tripartite occipital condyle composed of a laginis Meckelii is found with a small Meckel's groove medial projection from each exoccipital and ventrally proceeding anterior to this sulcus to the mandibular from a posterior projection of the basioccipital. symphsis. On the anterolateral surface, approximately C. No difference. six irregularly placed mental foramina are located. C. The Meckel's groove proceeding anterior from Fenestra ovalis. (Not figured) the Sulcus Cartilaginis Meckelii to the mandibular A. The fenestra ovalis is formed by the prootic

symphysis is more ventrally placed and there are eight and exoccipital bones and lies anterior to the pa- fairly evenly spaced mental foramina found along the roccipital process. lateral surface. C. No difference.

Splenial. (Fig. 7 and 8) Fenestra Rotundum. (Not figured) A. The splenial is found entirely on the medial A. The fenestra rotundum is formed by the surface of the ramus and articulates anteriorly with prootic and exoccipital and lies ventral to the fenestra its Posteriorly, the dentary along most of length. ovalis. articulation proceeds from dorsal to ventral with the C. No difference. coronoid, articular, and angular. One large foramen and one or perhaps two small splenial foramena are Hypoglossal foramen. (Not figured) evident. This bone covers the area of the Sulcus Carti- A. The hypoglossal foramen is found on the post- laginis Meckelii. eroventral side of the skull lateral to the occipital C. Relatively little difference is noted. condyles and entirely within the exoccipital. C. No difference. Surangular. (Fig. 7 and 8) A. The surangular forms the posterolateral wall of the ramus and articulates anteriorly from dorsal to Internal nares. (Fig. 2 and 5) ventral with the coronoid, dentary, and angular. The A. The internal nares are in the anteroventral surangular then proceeds along the ventral surface to the face of the skull and are surrounded by the maxilla,

posterior end where articulation is with the articular. palatine, and vomer. They form directly posterior to There are one large and two to six small surangular the vomeronasal organs of Jacobson. foramina found along the upper half of the bone. The C. No difference. surangular forms the lateral wall of the mandibular foramen. Infraorbital foramen. (Fig. 1 ,3, 4. and 6) C. There are only two foramina, one large and one A. The infraorbital foramen is surrounded by the small, located in the surangular. palatine, ectopterygoid, and pterygoid and lie on the anteroventral surface of the skull posterior to the Foramina of the Skull and Lower Jaw internal nares. C. No difference. In all cases, the foramina are considered comparatively in alphabetical order and positioning of

margining elements is from anterior to posterior, Infratemporal fenestra. (Fig. 3 and 6)

from dorsal to ventral, or lateral to medial as the case A. This is the large fenestra of the posterolateral applies. margin of the skull. The edges are formed by the jugal, postorbital-postfrontal, squamosal, pterygoid, Angular Foramen. (Fig. 7 and 8) and quadrate bones.

A. The angular foramen is located entirely within C. The ectopterygoid bone enters the anterolat- the angular. eral margin. BIOLOGICAL SERIES. VOL. 11, NO. 1 OSTEOLOGICAL AND MYLOGICAL COMPARISONS 17

Lacrimal foramen. (Not figured) supralabial scales.

A. The lacrimal foramen is formed from the C. The foramina are usually irregularly spaced and lacrimal and prefrontal to allow passage of the number four or five on each side. lacrimal canal. C. No difference. Supratemporal fenestra. (Fig. 1,2,4, and 5) A. This is the large posterodorsal fenestra of the Mandibular foramen. (Fig. 7 and 8) skull and is formed by the squamosal, parietal and

A. This is the large foramen of the posterodorsal tabular.

surface of each ramus. It is formed from the coronoid, surangular, and articular. C. No difference. C. No difference. Vomeronasal foramina. (Fig. 2 and 5) Mental foramina. (Fig. 7 and 8) A. The vomeronasal foramina are small, usually A. There are six irregularly spaced foramina of the three in number, and lie on the anteroventral surface lateral surface of each dentary bone. of the skull on each side of the midline. Housed in C. There are usually eight regularly spaced the vomer and bordered by the maxilla, they serve for foramina on each dentary bone. olfaction entrants by the tongue to the vomeronasal organs located within the nasal canal. Nasal foramina. (Fig. 8) C. No difference. A. Usually, 0-1 foramen are found in the anterior Teeth end of the nasal. C. Usually, -2 foramina are contained in the Dentary teeth. (Fig. 9a and 9c) nasal bone. A. The teeth are of pleurodont type with succession occurring throughout life by receiving re- Orbital fenestra. (Fig. 1, 2, 3, 4. 5, and 6) placement teeth which project into the base of the A. The orbital fenestra is located dorsally in the hollow, thinwalled old tooth. There are 22-23 teeth central portion of the skull and is formed by the pre- with the first 5 containing no accessory cusps. Begin- frontal, OS palpebrae, frontal, postorbital-postfontal, ning about tooth 6. there is a small anterior accessory lacrimal, and jugal. cusp and, about tooth 9, a posterior accessory cusp. C. No OS palpebrae is found on the anteriomedial Both of these accessory cusps continue posteriorly to border. the last tooth. C. The teeth also number 22-23, but only the first Palatine canal. (Not figured) 4 are peglike (without accessory cusps). Beginning A. Located ventral to the lacrimal foramen, this with tooth 5, a small anterior accessory cusp occurs canal is formed by the lacrimal, palatine maxilla, and and at tooth 20, the posterior accessory cusp is pterygoid. A small arch exists internally which added. appears to belong entirely to the maxilla. (Definite determination necessitates sectioning.) Maxillary and Premaxillary teeth. (Fig. 9b and 9d) lateral projection of the prefrontal enters the C. A A. The teeth of the premaxilla and maxilla are of margin of the canal. the same type as those of the dentary. Only the lateral four of the premaxilla are figured. The premaxilla Splenial foramina. (Fig. 7 and 8) bears 10 peglike teeth, the maxilla 18-21 teeth. The A. Located entirely within the splenial are two first maxillary tooth is peglike, but the second (6 in large small. foramina, one and one the figure) has an anterior accessory cusp. The third C. There are three foramina, one large and usually (7 in the figure) contains a posterior accessory cusp all within the splenial two small, and both cusps are retained posteriorly to the last tooth (23 in the figure). Surangular foramina. (Fig. 7 and 8) C. There are 8 peglike teeth on the premaxilla. A. Several foramina occur along the dorsal por- The first tooth of the maxilla (5 in the figure) bears usually consist of tion of the surangular bones. These an anterior accessory cusp and the sixteenth (20 in 2-6 foramina. one large and small the figure) adds a posterior accessory cusp. The last and one small C. Normally only one large foramen tooth (22 in the figure) may or may not possess the foramen are found in the surangular. posterior accessory cusp.

Supralabial Foramina. (Fig. 3 and 6) Pterygoid teeth. (Fig. 93) A. The supralabial foramina consist of approxima- A. No pterygoid teeth were found. tely six small regularly spaced foramina on the lateral C. There are five small peglike teeth occurring margin of the maxilla, positioned directly beneath the medially in the central portion of the pterygoid. BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN 18

30 13

A. Dentary teeth. (7.0X) B. Maxillary and Premaxillary teeth. (5.8X) Cnemidophorus tigris septentrionalis. Teeth. C. Dentary teeth. (11. OX) D. Maxillary and Premaxillary teeth. (9.7X) E. Pterygoid teeth. (20.0X)

Fig. 9. Ameiva undulata panm. Teeth. BIOLOGICAL SERIES. VOL. 11, NO. 1 OSTEOLOGICAL AND MYLOGICAL COMPARISONS 19

Wrist Muscles are named in alphabetical order rather

than by groupings into body areas in order to facil- The wrist of most teiids seems to consist of 8 or 9 itate cross-reference with the figures. Comparative carpal bones including carpals 1-5, a radiale, a prox- descriptions are listed the same as in the osteology imal central, an ulnare, and an intermedium which section with A. indicating the five specimens of may or may not be present. Each of the separate ele- Ameiva undiilata parva and "C." representing the six

ments is fully described by Avery and Tanner (1964), specimens of Cnemidophonis tigris septentrionalis

so the discussion is here limited to the highly variable observed. member of the carpal elements for the family Teiidae — the intermedium. M. Adductor Mandibulae Externus Medius. (Fig. 10, Stokely (1950) indicated that although this bone 16, and 17) Poglayen-Neuwall ( 1954). is highly characteristic of the lower tetrapods, partic- A. The fibers of this muscle originate from the ularly the amphibians, extinct reptiles and turtles, its medial surface of the squamosal, the posterolateral presence is highly variable in several saurian families. parietal projection, the dorsolateral beveled surface of One of these is the family Teiidae. He found the in- the parietal, and from the anterior and dorsal surfaces termedium absent in Cnemidophonis perplexiis, C. of the quadrate. The fibers extend anteroventrally melanostethus, Ameiva ameiva praesignis, Bachia in- with the dorsal ones more anteriorly directed. The termedia, and Opliiognomon abendwthi: but present insertion is along the dorsomedial surface of the sur- in Cnemidophonis gidaris. C. hyperythnis beldingi. angular and the posterior surface of the coronoid. and C. t. tessellatns. This extended the list of Camp The body of the muscle fills the supratemporal (1923) for the family Teiidae which included an fenestra and lies immediately medial to the adductor intermedium in Tupinambis nigropunctatus, Tejits mandibularis externus superficialis and dorsolateral to teguixin and Ameiva vulgaris. the adductor mandibularis externus profundus from Because of the apparent differences within the which it is only faintly separable. genus Ameiva and the genus Cnemidophonis, those C. Little difference is noted. specimens of these two genera accessioned in the Ver- tebrate Natural History Museum at Brigham Young Adductor Mandibulae Externus Profundus. (Fig. University were X-rayed and the radiographs carefully M. 17 and 18) Poglayen-Neuwall (1954). studied by means of a slide projector with the fol- A. The muscle originates from almost the entire lowing results obtained for the specific individual posteromedial border of the posterolateral projection specimens studied: 1. Intermedium present in C. c. of the parietal, from the paroccipital process of the communus, C. biirti. C. sexlineatiis, A. ii. parva, A. u. exoccipital and from the dorsolateral surface of the hartwegi, and A. u. sinistra. 2. Intermedium absent posterior process of the prootic. The muscle then in C. t. tigris, C. t. septentrionalis, C. gitlaris, and A. turns ventrally to enter the infratemporal fenestra auberi. 3. The presence of the intermedium is ques- and insert on the posterior surface of the coronoid. tionable in C. t. gracilis, C. t. caniis, C. t. aethiops, C. The muscle mass is not clearly separable from the exsanguis, C. d. deppei, C. I. lineatissimiis, C. hyper- adductor mandibularis externus medius in the dorso- ythrus, and C. lemniscatus. lateral position.

C. Little difference is noted. MYOLOGY M. Adductor Mandibularis Externus Superficialis. The determination of muscles and the naming of (Fig. 10, 16, 17) Poglayen-Neuwall (1954). them according to priority is difficult in the reptiles A. The origin is from the ventral surfaces of the because of extreme variability as well as a lack of postorbital-post frontal, squamosal, a portion of the agreement upon homologies. For the most part, jugal and from the dorsal and anterior surface of the names were here chosen which were of the oldest tympanic crest. The fibers of the muscle then extend origin as long as the muscle fit the general description anteroventrally to insert along the depressed lateral of the original author. Wliere this was not possible, surface of the surangular with the more anterior descriptive terminology for naming was applied. The fibers inserting on the lateral and posterolateral sur- deep skull musculature is not described here because faces of the coronoid and the lateral surface of the Poglayen-Neuwall (1954) has a very detailed account angular. The body of the muscle fills the greater of greater accuracy than was possible with the tech- portion of the infratemporal fenestra with the medial nique used in this report. These muscles include the portion scarcely distinguishable from the adductor levator bulbi dorsalis, levator bulbi ventralis, levator mandibulae externus medius. pterygoidei, protractor pterygoidei, pseudotemporalis C. Little difference is noted. profundus, and pseudotemporalis superficialis (Po- M. Adductor Mandibulae Posterior. (Fig. 17 and 18) glayen-Neuwall, 1954: Figs. 16, 9B). Poglayen-Neuwall (1954). 20 BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN

ADD. MAND. EXT SUPER.

ADD. MAND. EXT. MED.

PTERYGOMAND.

CERVICOMAND. DEPRESSOR MAND.

CONST. COLLI

DEITOIDEUS

LATISSIMUS DORSI

OBL. ABDOMINUS EXT INTERCOSTALIS EXT

A. Superficial deptli. B. First depth.

Fig. 10. Ameiva undulata parva. Musculature dorsal view. (2. 9X) BIOLOGICAL SERIES. VOL. 1 1 , NO. 1 OSTEOLOGICAL AND MYLOGICAL COMPARISONS 21

ADD. MAND. EXT. MED.

ADD. MAND. EXT. PRO.

PTERYGOMAND.

STYLOGLOSSUS

HYOGLOSSUS SPINALIS CAPITUS

STERNOCIEIDOMAST.

lONGISSIMUS LEV. SCAPULAE PRO LEV. SCAPULAE SUPER

DELTOIDEUS SERRATUS VENT. I DORSALIS SCAPULAE

SERRATUS DORSALIS

SERRATUS VENT. II

SERRATUS VENT. SUPER

OBL. ABDOMINUS EXT.

INTERCOSTALIS EXT.

A. Second depth. B. Third depth.

Fig. 11. Ameiva undulata parva. Musculature dorsal view. (2. 9X) UNIVERSITY SCIENCE BULLETIN 22 BRIGHAM YOUNG

SPINALIS CAPITUS L0NGISSIMU5

HYOGIOSSUS CERATOHYOIDEUS

M. ESOPHAGUS

IIIOCOSTAIIS SERRATUS DORSALIS

STERNOCORACOID. INF.

STERNOCORACOID SUP.

PROSCAPULOHUWERAIIS

INTERCOSTALIS INT INTERCOSTALIS EXT.

A. Fourth depth. B. Fifth depth.

Fig. 12. Ameiva undulata parva. Musculature dorsal view. (2.9X) BIOLOGICAL SERIES. VOL. 1 1 , NO. 1 OSTEOLOGICAL AND MYLOGICAL COMPARISONS 23

STYLOGIOSSUS

MYLOHYOIOEUS ANT.

MYIOHYOIDEUS POST.

GENIOHYOID

PTERYGOMAND CERVICOMAND.

OMOHYOIDEU5

CONST, coil STERNOHYOIDEUS

STERNOCLEIDOMAST

DEITIODEUS

CORACOHUMERAUS

PECTORAIIS

oil. ABDOMINIS EXT

A. Superficial depth. B. First depth.

Fig. 13. Ameiva undulata parva. Musculature ventral view. (2.9X) 24 BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN

MAND HYOIOEUS I

MAND. HYOIDEUS I! STYLOGLOSSUS

STYLOGLOSSUS

MAND. HYOIDEUS III PTERYGOMAND.

PTERY60MAND

M. ESOPHAGUS

OMOHYOIDEUS

STERNOHYOIOEUS

STERNOCLEIDOMAST. STERNOTHYROIDEUS

LEV. SCAPULAE SUPER

LEV SCAPULAE SUPER. LEV. SCAPULAE PRO LEV SCAPULAE PRO. STERNOCORACOID INF.

OELTOIOEUS

CORACOHUMERALIS

BICEPS

SCAPUIOTRI

SERRATUS VENT. SUPER

NTERC0STALI5 EXT OBL. ABDOMINUS EXT

A. Second depth. B. Third depth.

Fig. 14. Ameiva iindulata parva. Musculature ventral view. (2. 9X) BIOLOGICAL SERIES. VOL. 11, NO. 1 OSTEOLOGICAL AND MYLOGICAL COMPARISONS 25

HYOOIOSSUS

M. LARYNX

CERAT0HY0IDEU5

M. ESOPHAGUS

IIIOCOSTAIIS LONGIS COLLI

LONGIS COIL

STERNOCORACOID. INF.

PROSCAPULOHUMERALIS

INTERCOSTAIIS EXT. INTERCOSTALIS INT.

A. Fourth depth. B. Fifth depth.

Fig. 15. Ameiva undulata parva. Musculature ventral view. (2. 9X) 26 BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN

ADO. MAND. EXT. SUPER

ADD. MAND. EXT. MED.

SUPRALABIAl LI6.

PTERYOOMAND.

DEPRESSOR MAND.

GENIOHYOID

LEV. SCAPULAE SUPER.

STERNOCIEIDOMAST. LEV. SCAPULAE PROF.

OMOHYOID

OORSALIS SCAPULAE

TRAPEZIUS

DEITOIDEUS

BICEPS

HUMEROTRICEPS LAT.

lATISSIMUS DORSI SCAPULOTRICEPS

OBL. ABDOMINUS EXT.

First depth.

Fig. 16. Ameiva undulata parva. Musculature lateral view. (2.9X) BIOLOGICAL SERIES. VOL. 1 1 , NO. 1 OSTEOLOGICAL AND MYLOGICAL COMPARISONS 27

ADD. MANO. EXT. PRO. ADD. MAND. EXT. SUPER.

ADD. MANO. EXT MED. ADD. MANO. POST.

PTERYGOMAND. STYLOGLOSSUS

HYOGIOSSUS STERNOTHYROIDEUS OMOHYOIDEUS SPINALIS CAPITUS STERNOCIEIDOMAST LONOISSIMUS STERNOCORACOID INF.

LEV. SCAPULAE PRO.

DELTOIDEUS LEV. SCAPULAE SUPER.

DORSAIIS SCAPULAE

BICEPS

HUMEROTRICEPS lAT.

SERRATUS VENT SUPER

SCAPULOTRI.

OBL. ABDOMINUS EXT. INTERCOSTALIS EXT.

Second depth.

Fig. 17. Ameiva undulata parx'a. Musculature lateral view. (2.9X) 28 BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN

ADD. MANO. EXT. PRO.

ADD. MAND. POST.

PTERYGOMAND.

SPINALIS CAPITUS

OENIOHYOIDEUS lONOISSIMUS

ILOCOSTAIIS STERNOTHYROIDEUS

M. ESOPHAOUS

LEV. SCAPULAE SUPER.

LEV. SCAPULAE PRO.

SCAPULOTRICEPS

INTERCOSTALIS EXT.

Third depth.

Fig. 18. Ameiva undulata parra. Musculature lateral view. f2.9X) BIOLOGICAL SERIES. VOL. 1 1 , NO. 1 OSTEOLOGICAL AND MYLOGICAL COMPARISONS 29

M. ESOPHAGUS

SPINALIS CAPITUS

ILIOCOSTALIS HYOGIOSSUS lONcis com

lONGISSIMUS

SERRATUS DORSALIS

STERNOCORACOID. INF.

PROSCAPULOHUERALIS

TRANS. THORACIS

INTERCOSTAIIS INT.

INTERCOSTAIIS EXT.

Fourth depth.

Fig. 19. Ameiva undulata parva. Musculature lateral view. (2.9X) 30 BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN

lONGISSIMUS

LONGIS COLLI ^

LIOCOSTALIS

STERNOCORACOID. SUP. TRANS. THORACIS

INTERCOSTALIS INT

Fifth depth.

Fig. 20. Ameiva undulata parva. Musculature lateral view. (2.9X) BIOLOGICAL SERIES. VOL. I 1 , NO. I OSTEOLOGICAL AND MYLOGICAL COMPARISONS 31

A. Some of the fibers of this muscle arise from A. This is a short muscle arising from the anterior the lateral and medial surfaces of an aponeurosis margin of the scapulae slightly dorsal to the biceps which extends along the medial crest of the quadrate, brachii and inserting mostly under cover of the del- whereas the other fibers originate from the posterior toideus and the pectoralis on the proximal end of the process of the prootic. The fibers all pass antro- humerus. ventrally and insert on the dorsal surface of the artic- C. Little difference is noted. ular. The body of the muscle is thin and lies lateral to the tympanic cavity and medial to the mandible and M. Dehoideus. (Fig. 10, 13, 14, 16, and 17) Howell the adductor mandibularis externus. (1936).

C. Little difference is noted. A. The origin of the deltoideus is at the inner M. Biceps Brachii. (Fig. 10. 11, 13, 14, 16, 17, and margin of the ventral two-thirds of the clavicle with 18) Howell (1936). fibers fusing at the insertion with those of the dorsalis A. The fibers of this muscle arise near the scapulae and attaching upon the lateral portion of the proximal head of the humerus on the posterior edge proximal end of the humerus. of the scapulae, form a long, broad tendon, and pass C. Little difference is noted. along the ventral surface of the humerus to insert on the proximal head of the radius. M. Depressor Mandibulae. (Fig. 10, 16, and 18) Po-

C. Little difference is noted. glayen-Neuwall (1954). A. The depressor mandibulae originates on the middorsal fascia in the area of the cervical vertebrae M. Ceratohyoideus. (Fig. 12 and 15) Gnanamuthu 1-5 and inserts on the posterior end of the retro- (1937). articular process of the articular. The body of the A. This is a thin muscle which proceeds between muscle lies on the lateral surfaces of the cervical ceratobranchial I and ceratobranchial 2. Dorsally, it region and borders the auditory meatus anteriorly contacts the oral membrane and lies dorsal to the and in this area is superficial to some of the posterior hyoglossus. fibers of the adductor mandibularis externus medius C. Little difference is noted. and posterior border of the tympanum. Posteriorly, it M. Cervicomandibularis. (Fig. 10 and 13) Camp passes superficial to the anterior fibers of the trap- (1923). ezius and the sternocleidomastoideus. The cervico- A. The fibers of this muscle extend from the mid- mandibularis and constrictor colli overlie most of the dorsal fascia to the midventral raphe proceeding pos- body of the muscle. terior to the external auditory meatus and superficial C. Little difference is noted. to the pterygomandibularis and the majority of throat muscles. It lies just internal to the skin, and M. Dorsalis Scapulae. (Fig. 10, 11, 16, 17, and 18) posteriorly the muscle is separated from the con- Howell (1936). strictor colli by a narrow area of aponeurosis lacking A. The dorsalis scapulae originates along an muscle fibers. oblique line extending from a point near the dorso- C. The division between the cervicomandibularis caudal portion of the suprascapula to the clavicle. and the constrictor colli dorsally is less distinct with Origin is both from the dorsal portion of the clavicle an anteroventral extension proceeding almost to the and the dorsal margin of the girdle. The insertion is center of the dentary and covers most of the genio- fused with that of the deltoid and attachment is upon hyoid and some of the mylohyoideus complex. the lateral portion of the proximal end of the

humerus. The body of the muscle is deep to the trapezius superficial to the serratus ventralis M. Constrictor Colli. (Fig. 10 and 13) Camp (1923) and compex and the proscapulohumeralis. part of the origin is A. The muscle is the most superficial of the cer- A vical and thorax region, arising from the superficial covered by the latissimus dorsi. dorsolateral fascia of the neck and passing ventrally C. Little difference is noted.

to insert on the extensive ventral raphe. It is internal M. Genioglossus. (Not figured) Camp (1923). only to the connective tissue of the skin and a few A. This is a small muscle originating deep to the

scattered fat pads. It is superficial to the depressor insertion of the mylohyoideus anterior on the medial mandibulae and the sternocleidomastoid dorsally and surface of the dentary. It inserts into the ventral

ventrally it overlies the sternohyoideus, omohyoideus anterolateral portion of the tongue.

and a portion of the deltoideus. C. Little difference is noted.

C. The extent of the constrictor colli is more dif-

ficult to determine dorsally as it is somewhat fused M. Geniohyoideus. (Fig. 13, 16, and 18) Camp with the cervicomandibularis. (1923). A. The origin of the geniohyoideus is along the M. Coracohumeralis. (Fig. 13 and 14) Howell (1936). anterior margin of ceratobranchial 2 of the hyoid 32 BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN apparatus and inserting in five slips along the medial abdominus externus, the serratus complex and the surface of the dentary. The medial edge is continuous levator scapulae complex. It is superficial to the inter- with most of the processus etoglossus which is the costalis internus and transversus thoracis. medial anterior projection of the hyoid apparatus C. Little difference is noted.

(Fig. 15). The body of the muscle is superficial to the mandibulohyoideus complex, a greater portion of the M. Intercostalis Internus. (Fig. 12, 15, 19, and 20) ventral surface of the pterygomandibularis, the sty- Smith (1960). loglossus and hyoglossus. It is deep to the mylohy- A. The origin of the intercostalis internus is on oideus complex and the cervicomandibularis. the ribs with the fibers extending ventrally and C. The insertion is by three slips with the anterior slightly anteriorly to insert on the next anterior rib or portion continuously in contact with the posterior the sternal portion of the same rib. It is deep to the one-third of the processus etoglossus. intercostalis externus and superficial to the transversus thoracis.

M. Humerotriceps Lateralis. (Fig. 10, 11, 13, 14, 16, C. Little difference is noted. and 17) Howell (1936). A. A muscle of the laterocentral surface of the M. Laryngi. (Fig. 15 and 20) Smith (1960). humerus, the humerotriceps lateralis has its origin on A. Muscles of the larynx are small and complex the head of the humerus with fibers running distally with complete dissection difficult with the technique to insert on the olecranon process of the ulna. used in this report. They are here considered as one

C. No difference is noted. group of muscles surrounding the laryngeal cartilages. Homologies within the vertebrates need to be deter- M. Humerotriceps Medialis. (Not figured) Howell mined before the individual muscles of the larynx will (1936) be of significance.

A. This is a muscle of the mediocentral surface of C. Little difference is noted. the humerus with its origin on the medial side of the humeral head and extending along the entire shaft of M. Latissimus dorsi. (Fig. 10 and 16) Howell (1936). the humerus to insert on the olecranon process of the A. The latissimus dorsi originates in the thoracic ulna. region of the middorsal fascia with its anterior fibers

C. No difference is noted. running posteroventrally and its posterior ones anteroventrally to insert near the origin of the scapulotri- M. Hyoglossus. (Fig. 11, 12, 14, 15, 17, 19) Oelrich ceps of the brachium onto the proximal end of the

(1956). humerus. It is a sheetlike muscle which covers an ex- A. The hyoglossus originates on the posterior por- tensive portion of the lateral body surface, having anter- tion of ceratobranchial 2 of the hyoid apparatus and odorsal fibers deep to the trapezius while the remain- forms the body of the tongue. It is a thick broad mus- ing ones are deep only to the skin. It is superficial to cle lying lateral to the ceratobranchial 2 and medial the serratus ventralis superficialis and a portion of the to the mandibulohyoideus HI and the pterygomandi- dorsalis scapulae. bularis and is deep to the mandibulohyoideus I and C. Little difference is noted.

II, the styloglossus and the geniohyoideus. It is superficial to the ceratohyoideus and the esophagus. M. Levator Scapulae Profundus. (Fig. II, 14, 16, 17, C. Little difference is noted. and 18) Howell (1936). A. This muscle originates from the transverse M. Iliocostahs. (Fig. 12, 15, 18, 19, and 20) George process of the atlas and inserts on the ventral one-

(1948). third of the anterior border of the suprascapulae. It is A. The iliocostalis takes a multiple origin from the a ventral partner to the levator scapulae superficialis ilium and fascia of the longissimus with some inser- and lies in approximately the same position with relation on the anterior ribs. The anterior insertions, tion to the surrounding muscles. however, are on the atlas vertebra and the occipital C. Little difference is noted. region of the skull. The body of the muscle lies ventrolateral to the longissimus and dorsal to the longus M. Levator Scapulae Superficialis. (Fig. 10. 11, 14, colli. 16, 17, and 18) Howell (1936).

C. Little difference is noted. A. The muscle originates by means of a tendon in common with the levator scapulae profundus from M. Intercostalis Externus. (Fig. 11, 12, 14, 15, 17, the transverse process of the atlas and extends poster- 18, and 19) Smith (1960). odorsally to insert on the dorsal two-thirds of the

A. The fibers of the intercostalis externus origi- anterior border of the suprascapula. It is a broad, nate on the ribs and extend posteriorly to insert on fan-shaped muscle which lies dorsal to the levator the next posterior rib. It is deep to the obliquus scapulae profundus and superficial to the axial mus- BIOLOGICAL SERIES. VOL. 11, NO. 1 OSTEOLOGICAL AND MYLOGICAL COMPARISONS 33 culature and the posterodorsal fibers of the iliocost- hyoideus at its posterior end. ahs. The body of this muscle is deep to the constric- C. Little difference is noted. tor colli, the trapezius and the posterior portion of the depressor mandibulae. M. Mylohyoideus Anterior. (Fig. 13) Camp (1923).

C. Little difference is noted. A. The mylohyoideus anterior is a small strip of muscle extending anterolaterally on the ventral surface of the throat, originating on the midventral M. LongusCoUil.(Fig. 15, 19, and 20) Smith (1960). raphe and inserting between the genioglossus and the A. This is the most ventral of the deep neck mus- geniohyoid onto the medial surface of the dentary. cles originating on the centra of the first thoracic ver- C. This is the most prominent portion of the tebrae and inserting on the lower portion of the cen- mylohyoideus and makes a definite division between tra of each of the cervicle vertebrae. the genioglossus and the geniohyoid. C. Little difference is noted.

M. Mylohyoideus Posterior. (Fig. 13) (Camp 1923)

M. Longissimus. (Fig. 11. 12, 17, 18, 19, and 20) A. The mylohyoideus posterior originates on the George (1948). midventral raphe just posterior to the mylohyoideus A. The longissimus originates from the ilium, sac- anterior and immediately breaks into 9 separate divisions prominent and 5 minor) which insert rum, and the neural arches; from these it proceeds (4 by anteriorly to insert on part of the neural arches of the interdigitation with slips of the geniohyoideus. The divisions is anterior vertebrae and on part of the skull at the junc- most posterior of the partially covered by tion between the parietal, supraoccipital, and a small the cervicomandibularis. portion of the paroccipital process of the exoccipital. C. The muscle has only 5 divisions (3 major and 2 minor), all rather small and indistinct. C. Little difference is noted.

M. Obliquus Abdominis Externus. (Fig. 1, 14, 16, and M. Mandibulohyoideus I. (Fig. 14) Oelrich (1956) 17) George (1948). A. This is a slightly triangular muscle originating on the central portion of the dentary and extending A. The origin of this muscle is by separate heads from aponeurotic tendons of the lateral and posterior two-thirds the length of the ramus to insert on the surfaces of the second through eighth ribs near their ceratohyal. It lies medial to the mandibulohyoideus dorsal articulations. The fibers then extend postero- 11, extending deep to the cervicomandibularis and ventrally to insert along the lateral border of the superficial to the styloglossus, hyoglossus, and mandibulohyoideus in. abdominal musculature. The muscles of the abdominal region are highly fused to the ventral scutellation C. Little difference is noted. and thus difficult to detach. The body of the muscle

is a thin, extensive sheet which covers most of the

M. Mandibulohyoideus IL (Fig. 14) Oelrich (1956). lateral surface of the body and is deep only to the

A. This is a short pointed muscle which originates trapezius and the latissimus dorsi. on a posterior portion of the dentary and inserts on C. Little difference is noted. the anterior portion of the ceratohyal. It lies lateral to the mandibulohyoideus 1 and medial to the man- M. Omohyoideus. (Fig. 13, 14, 16, and 17) Gnana- dibulohyoideus in, running deep to the cervicoman- muthu(1937). dibularis and superficial to the tongue, styloglossus A. This is a thick muscle of the ventrolateral sur- and the hyoglossus. The body of the muscle is face of the neck, having its origin on the anterior bor- approximately the same width as the mandibulohy- der of the scapula and then proceeding anteroven- oideus I. trally to insert on the proximal end of the basihyal

C. The muscle is much reduced in width to about and along ceratobranchial 2. It is deep to the poste- one-half that of the mandibulohyoideus I. rior portion of the cervicomandibularis and the anterior portion of the constrictor colli, superficial to the M. Mandibulohyoideus 111. (Fig. 14) Oelrich (1956). anterior portion of the sternothyroideus and a small

A. This is a flat sheet of muscle originating on the portion of the esophagus, and lies lateral to the stern- posterior-most portion of the dentary and a small ohyoideus. portion of the angular with its insertion on the cerat- C. The muscle is much broader, covering the obranchial 1. It extends almost parallel to the man- sternohyoideus to an area midway between the hyoid dibular ramus across the mass of the apparatus and the sternum. pterygomandibularis and is more or less attached to it by connective tissues. The body of the muscle is deep M. Pectoralis. (Fig. 13) Camp (1923). to the mandibulohyoideus and geniohyoideus, but is A. The pectoralis is an extensive superficial mus- superficial to the styloglossus, hyoglossus and cerato- cle of the sternal region, originating from the inner 34 BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN angle of the clavicle, the interclavicle, the sternum what dorsal to the ventral slips. and the midventral raphe and inserting on the proxi- C. Little difference is noted. mal end of the humerus. It is superficial to the sternum, some of the sternal ribs and the coracoid and is M. Serratus Ventralis I. (Fig. 1 1) Howell (1936). deep only to the skin of the chest region. A. The serratus ventralis I originates centrally C. Little difference is noted. slightly beneath the serratus dorsalis on the first two ribs and inserts on the anteromedial border of the

M. Proscapulohumeralis. (Fig. 12, 15, and 19) Howell scapula. The body of the muscle is deep to the sub- (1936). scapularis and supervicial to the intercostalis A. The proscapulohumeralis originates on the externus. fibers anteroventral margin of the scapula with pro- C. Little difference is noted. ceeding ventrally which immediately join those of the coracohumeralis of the same layer. Toward the inser- M. Serratus Ventralis II. (Fig. II and 18) Howell tion, the latter muscle passes over a small ligament (1936). while the former passes beneath it to insert upon the A. This muscle originates immediately ventral to humerus between the medial and lateral heads of the the last slip of the serratus dorsalis and its origin is humerotriceps. It lies superficial to the sternocora- centrally on the posteromedial portion of the scapula coideus superior and deep to the deltoideus. and is immediately ventrolateral to the serratus ven- C. Little difference is noted. tralis I.

C. Little difference is noted. M. Pterygomandibularis. (Fig. 10, 11, 13, 14, 16, 17 and 18)Oelrich(1956). Serratus Ventralis Superficialis. (Fig. 10, 14, and A. This is the largest muscle of the lateral surface M. of the skull, originating on the pterygoid along the 17) Howell (1936). margin of the infraorbital foramen by means of a A. The muscle originates by means of several slips large tendon attached to the ectopterygoid process. from the first two ribs, then proceeds anterodorsally The fibers extend posteriorly and posterodorsally to to insert on the posterior border of the scapula. The cover the ventral and lateral surfaces of the angular body of the muscle is deep to the latissimus dorsi and and surangular they then continue posteriorly along superficial to serratus ventralis I and II as well as the condyle of the quadrate and insert on the angular intercostalis externus. process of the articular. It is deep to the cervicoman- C. Little difference is noted. dibularis dorsally and the mandibulohyoideus III ventrally and lies superficial to the esophagus. M. Spinalis Capitus. (Fig. 11, 12, 17, 18, and 19) C. The muscle is not as bulky, but otherwise little George (1 948). difference is noted. A. This is the large anterior epaxial muscle originating in common with the spinalis cervicis and in- M. Scapulotriceps. (Fig. 11, 13, 14, 16, 17, and 18) serting on the posterior margin of the parietal. It is Howell (1936). deep only to the middorsal fascia and the dorsal por- A. The origin of the scapulotriceps is on the scap- tion of the cervicomandibularis and is superficial to ula near the glenoid fossa. The fibers then loop the longissimus, iliocostalis and longus colli. around the insertion of the latissimus dorsi and pro- C. Little difference is noted. ceed distally to sinert on the olecranon process of the ulna. M. Sternocleidomastoideus. (Fig. II, 13, 14, 16, and C. Little difference is noted. 17) Howell (1936). A. Sometimes called the episternocleidomastoid

M. Serratus Dorsalis. (Fig. 11, 12, 18, and 19) Howell (Robison and Tanner, 1962), it is a thick, ribbonlike (1936). muscle obliquely crossing the lateral surface of the A. This muscle consists of three ribbonlike slips of cervical region, originating by a superficial aponeuro- muscle which partially overlap one another in such a sis from the posterior cranial region along the way that they appear serratuslike from a dorsal view extreme posterolateral margin of the parietal and the when the suprascapula is pried away from the lizard's parietal process and inserting along the dorsal margin body (as in Fig. 1 IB). It arises by fasciculae from the of the clavicle with a small slip attaching to the ante- lateral surfaces of the three cervical ribs and then rior portion of the sternum. Anterodorsally, it is deep passes slightly dorsolaterally to insert separately, but to the depressor mandibularis; otherwise, it lies super- slightly overlapping one another, along the medial ficial to the sternothyroideus, levator scapulae pro- surface of the suprascapula near its dorsal border. fundus and superficialis, and the deep epaxial mascul-

Althougli the muscle is partially continuous with the ature. serratus ventralis complex, it lies medial and some- C Little difference is noted. BIOLOGICAL SERIES. VOL. 11, NO. 1 OSTEOLOGICAL AND MYLOGICAL COMPARISONS 35

M. Sternocoracoideus Inferior. (Fig. II, 12, 14, 15, M. Subscapularis. (Not figured) Howell (1936). 17, 18, and 19) Howell( 1936). A. The subscapularis arises from the base of the

A. This is a somewhat confusing muscle which medial side of the suprascapula and the adjoining por- arises from the ventral surface of the sternum and tion of the scapula; its fibers converge to a tendinous proceeds anteriorly over the end of the clavicle and insertion upon the retractor process of the humerus.

inserts on the ventral coracoid end of the scapula thus It is deep only to the scapula, but is superficial to the covering the clavicle almost entirely. serratus ventralis complex as well as a portion of the

C. Little difference is noted. serratus dorsalis.

C. Little difference is noted. M. Sternocoracoideus Superior. (Fig. 15 and 20) Howell (1936). Supralabial Ligament. (Fig. 16) New Name.

A. The sternocoracoideus superior is an internal A. This is a strong superficial ligament of the sternal muscle originating from most of the dorsal lateral surface extending beneath the supralabial surface of the sternum and inserting by a broad thin scales of the skin from the rostral area to insert on

tendon on the ventral portion of the scapula, appear- the anteroventral margin of the quadrate. It is deep ing to insert on the clavicle. only to the fascia of the skin and is superficial to the

C. Little difference is noted. pterygomandibularis.

C. Little difference is noted. M. Sternohyoideus. (Fig. 13 and 14) Camp (1923).

A. The sternohyoideus is a relatively broad, flat M. Transversus Thoracis. (Fig. 19 and 20) Smith muscle of the ventral surface of the neck region. It (I960' originates on the sternum and inserts on portions of A. In contact with the peritoneal membrane inter- the basihyal and anterior section of ceratobranchial 2. nally, the transversus thoracis arises by means of It lies medial to the omohyoideus anteriorly and the fascia from the pelvis to the neck region and lies, for sternocleidomastoideus posteriorly. It is deep to 'the the most part, between the second thoracic vertebra posterior portion of the cervicomandibularis and an- and the humerus. Its fibers extend almost vertically terior portion of the constructor colli and lies super- and insert on the inner surfaces of the thoracic ribs, ficial to the esophagus. the lateral border of the sternum, and the dorsal sur- C. Little difference is noted. face of the abdominal musculature. It is deep to all of the thoracic musculature. M. Sternothyroideus. (Fig. 14, 17, and 18) Camp C. Little difference is noted. (1923).

A. This is a large flat muscle extending along the ventrolateral side of the neck, originating in a sheet from the anterior portion of the sternum and insert- M. Trapezius (Fig. 10 and 16) Howell (1936).

ing along most of the posterior length of cerato- A. This is an extensive, superficial muscle located

branchial 2. The body of the muscle lies deep to the on the dorsolateral surface of the cervical and tho- sternocleidomastoideus and the posterior portion of racic regions. It is the most superficial muscle of the

the omohyoideus. It is superficial to the esophagus. area with the exception of the depressor mandibularis

C. Little difference is noted. and the constrictor colli which originate on the middorsal raphe in the area of the lower cervicals and M. Styloglossus. (Fig. 11, 13. 14, and 17) Smith insert on the crest of the anterior margin of the supra- (1960). scapula, the superficial fascia along the clavicle and

A. Although the exact extent of this muscle is the anterior margin of the pectoralis to the origin of

somewhat questionable because of the fascia on its the sternocleidomastoideus. This muscle varies greatly its Posteriorly, it is posterodorsal surface, it appears to originate by in thickness throughout extent. means of a thin sheet of fascia from the posterior considerably developed, this being the major part to region of the cranium and quadrate and inserts on the insert on the suprascapula. However, anteriorly, it mandibular symphysis of the dentaries. It covers the comes to be only one muscle layer in thickness. The hyoglossus and forms a small part of the basal sheath body of the muscle is superficial to the levator scap- which covers the posterior margin of the tongue. ulae superficialis and profundus as well as the dorsal C. The origin appears almost tendinous postero- portion of the dorsalis scapulae. dorsally and anteroventrally no basal sheath is con- C. Little difference is noted. tributed to the tongue. 36 BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN

DISCUSSION

Phylogenetic speculations on reptiles have been orbit. In the lower jaw, there is a slight lateral torsion based upon information derived from three areas: (1) of each ramus, the articular and angular are at almost the fossil record, (2) the geographic distribution, and right angles to each other, and the ventral surface of

(3) the comparative morphology of living genera the dentary is rugose. In C. t. septentrionalis, the (Camp, 1923). The third area has been the main focus skull is comparatively lighter with a relatively glab- of attention in this report. The most reliable hypothe- rous dorsal surface. There is little indication of inden- ses of phylogeny require careful examination of all tation of integumentary scutellation and the anter- potential data; therefore definitive phylogenetic con- omedial border of the orbit is cartilaginous. In the clusions are not justified by this study. Howes (1902) lower jaw, there is no lateral torsion, the articular and discussed the idea that comparative morphology is angular essentially form a straight line, and the the primary practical basis of a working classification. ventral surface of the dentary is relatively glabrous. He further noted that comparisons should be first For further references to variation of the separate made on closely related forms, passing later to larger elements is noted in the general description. Elements and less closely related groups. The present compari- discussed in which a difference is noted include the sons, restricted to Cnemidophorus and Ameiva pro- basioccipital, ectopterygoid, exoccipital, frontal, vide an initial step. The genus Cnemidophorus is a jugal, lacrimal, maxilla, nasal, os palpaerae, palatine, probable offshoot oi Ameiva as speculated by Bar- parietal, postorbital-postfrontal, prefrontal, premax- bour and Noble (1915) and as well by Burt (1931b). illa, prootic, pterygoid, quadrate, supraoccipital, and Camp (1923) listed 34 different paleotelic charac- most of the elements of the lower jaw except the ters of importance in considerations of phylogeny as splenial. determined by comparative morphology. Althougli The most unstable element of osteological import some of these characters are of little significance appears to be the intermedium of the wrist. Romer below the family level, those which are of importance (1956) points out that fusion and sometimes com- to phylogeny of the genera discussed in this report plete loss of some wrist bones is common in lizards. include in the order of significance listed by Camp: With the methods used in this report, an element as (1) fusion of median skull elements, (2) the postor- minute as the intermedium is difficult to locate on bital-postfrontal, (3) the lacrymal, (4) mandibular small specimens and may account for its apparent teeth, (5) palatine teeth, (6) throat masculature, (7) absence in some of the species and subspecies the lower jaw, (8) the os intermedium (9) the epipter- observed. Possession of this element may indicate ygoid, and (10) the shoulder masculature. These are primitiveness, but this is questionable because of its not all of the phylogenetically significant characters variation even between subspecies. The degree of ossi- which have been discussed in such texts as those by fication of this structure and other carpals is probably

Smith (1960) and Romer (1964), but the list may a function of age of the individual. It is recognized lend an index to phylogenetic studies. that a need for using larger series in most of the spe- In the following discussion, osteological variables cies is necessary for a complete study; however, the are treated first, then myological variables. The two data presented seems significant since all of the sets of variables together should provide a more reli- Ameiva uudulata group examined appear to possess able bases for speculation on phylogenetic relation- the element whereas it is seemingly absent in exam- ships than one of them alone. As pointed out by ples of the Cnemidophorus tigris group examined by Nopcsa (1928), osteological characters alone are us. insufficient to distinguish all of the Teiidae from all of the Iguanidae, for example, and it is probable that Teeth. the reverse is also true. The teeth of A. u. parva and C. t. septentrionalis show some similarity of shape and relative size, but Osteology. they differ considerably in the positioning and num- Elements of the skull and lower jaw (as indicated ber of cusps on specific teeth. Perhaps the greatest in fig. 1-8) show considerable variation between the difference noted was the absence of pterygoid teeth members of the two genera described. Considerable in A. u. parva. Camp (1923) suggests that the pres- variation is noted in the general appearance of the ence of these teeth may be of paleotelic significance, skull and lower jaw. In A. u. parx'a, the skull can be but he hastened to add that the absence of such teeth considered heavily ossified with a rugose dorsal may or may not be of significance owing to the likeli- surface; deep indications of indentation for in- hood of dropping out or the migration and develop- tegumentary scutellation are evident and an os pal- ment of cutaneous tooth buds from one bone to pebrae is evident in the anteromedial border of the another in the course of recent phylogeny. BIOLOGICAL SERIES. VOL. 1 1 , NO. 1 OSTEOLOGICAL AND MYLOGICAL COMPARISONS 37

Age is also exhibited by tooth structure of both genera, this could perhaps be used as a tool for inter- genera as the older specimens have some of the pos- pretation of phylogenies and variations. terior accessory cusps well worn or reduced to small The greatest myological variation appears to be swellings. Several of the teeth are also loose or miss- centered around the anterior segments of the ventral ing (replacement) and broken. musculature. In A. u. parva, the mylohyoideus complex interdigitates frequently with the geniohyoideus

by nine separate bundles, whereas in C. t. septentrionalis this complex interdigitates in only five bundles of Myology. rather simple structure. Camp (1923) seems to believe

The problems of myological research are at times that the variation in this musculature is a good indi- rather complex. Huntington (1903), Camp (1923), cator of primitiveness. He pointed out that above the

Romer (1956) and Smith (1960) indicate that the family level a primitive saurian condition is repre- musculature of major groups such as orders and sented by eight or more interdigitation bundles of classes is rather plastic and variable and are, thus, these two muscle groups. rather difficult to interpret. At the family level, how- Other myological variations iox A. ii. parva include ever, myology appears to be a sufficiently stable char- a distinct division of the cervicomandibularis by the acter to be of phylogenetic use. Tanner ( 1952) indi- constrictor colli, a mandibulohyoideus II which is the cated that in Mexican and Central American groups same width as the mandibulohyoideus I, and an omo- of the salamander family Plethodontidae the musucla- hyoideus which is rather narrow and located ventro-

ture is consistent enough to define genera. This con- laterally in the neck region. In C. t. septentrionalis, clusion has been further supported by Wake (1966) there is a dorsal fusion of the cervicomandibularis on the osteology of the plethodontid salamanders and with the constrictor colli, the mandibulohyoideus II by work in reptilian myology by Robison and Tanner is only one-half the width of the mandibulohyoideus

(1962), and Avery and Tanner (1964). The two gen- I, and the omohyoideus is relatively broad, extending era of the family Teiidae examined in this report ventrally to the midcentral region of the neck. seem to support this conclusion. Of the forty-nine The differences in configuration of these muscles

muscles dissected in A. u. pan'a and compared in C. t. may indicate that the variability is not suited for septentrionalis. only six differed significantly phylogenetic comparisons between these two genera, between the two genera as far as configuration, or they may support the distinction of the two gen- origin, insertion, or size was concerned. Because of era. Further study of the entire family would be nec- the relative stability of the myology within these two essary before definitive conclusions could be reached.

CONCLUSIONS AND SUMMARY

The anterior osteological elements of the skull, fusion of elements and exact suturing is diffi- lower jaw, and wrist along with the anterior myologi- cult to distinguish. In C. , the occipital elements cal characters discussed and figured in this report sug- are easily distinguished. gest that A. II. pan'a and C. t. septentrionalis are members of distinct groups which can be differenti- 2. Skull elements. ated by internal morphologic characters. Although Those elements of greatest difference and comparisons were restricted to highly geographically significance are noted in the sections titled separated individuals of the same family, their general descriptions and discussion. The elements in- body form and structure appear to be similar. clude the ectopterygoid. exoccipital, frontal, A great number of anatomical structures are jugal, OS palpebrae, postorbital-postfrontal, pre- shared in common, but the significant differences maxilla, and the quadrate. between them include:

3. Lower jaw elements.

1 . General skull appearance. Those elements of greatest difference and

The skull of C. is generally lighter, that is significance are noted in the sections titled the bones are thinner, than in A. and with a descriptions and discussion. The elements larger portion relatively glabrous on the dorsal include the angular, articular, and dentary.

surface with little indication of integumentary scutellation. The most notable differences are 4. Foramina of the skull and lower jaw.

found in the occipital region of .4. where much The foramina of significant difference 38 BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN

between the two genera are noted in the sec- plex interdigitates frequently with the geniohy- tions titled description and discussion. These oideus in A. u. parva. Nine separate bundles include the infratemporal fenestra, mental for- were found in the species studied. Camp (1923) amina, nasal foramina, palatine canals, splenial stated that above the family level in suarians, foramina, surangular foramina, and the supra- eight or more bundles was a valid indicator of labial foramina. primitiveness. The other muscles of generic variation include the m. cervicomandibularis, m.

5. The teeth of the maxilla, dentary, and ptery- constructor colli, m. mandibulohyoideus II, m. goid. omphyoideus, m. styloglossus and the associ- The teeth are mostly peglike with the first ated basal tongue sheath. accessory cusp of the dentary appearing on tooth 5 in C. and tooth 6 in A. There are eight The anatomical differences existing in the sheath

peglike teeth on the premaxilla of C. and ten associated with the tongue of^. u. parva is of special

on the premaxilla of A. The greater number is a significance. A basal sheath is connected to the probable indicator of greater antiquity. In the tongue sheath and extends for attachment to cranial maxilla a posterior accessory cusp is found on and mandibular bones. This establishes a real anatom-

the second tooth ofy4. and the sixteenth of C ical basis for the tongue sheath character now used by Perhaps the most significant point is that five some to separate these genera. Further exploration of peglike teeth occur on the pterygoid of C and species in these genera should be made to determine

none were found on A. the stability of the character. This is particularly true in view of the comments made by Burt (1931b) con- 6. The intermedium wrist element. cerning this structure, which, based on his findings, An intermedium was found to be present in may be an inadequate character to separate these gen- the manus of C. communis, C. gularis, C. burti, era.

C. sexlineatus, A. u. pan>a, A. it. hartwegi, and It is evident from the findings that specialization

A. u. sinistra. It is either absent or questionably has occurred not only intergenerically but intragener-

present in C. t. tigris, C. t. septentrionalis, C. t. ically, and care must be taken to distinguish the two

gracilis, C. t. caniis, C. t. aethiops, C. gularis, C. levels of variation. Clearly the presence or absence of

exsanguis, C. d. deppei, C. d. lineatissisimus, C. the intermedium is of little significance intergener- h. hyperythrus, C. o. lemniscatus, and A. ically, but may be of importance intragenerically. The

auberi. It is evident from the above distribution presence or absence of the pterygoid teeth may also

that the presence or absence of the interme- fit this category, but with our present understanding dium may not be of paleotelic significance at of its paleotelic significance within this family it is the generic level, but may be at the specific impractical to draw a conclusion. Barbour and Noble level. It may also be intraspecifically variable. (1915) and Burt (1931b) concluded from their study of external morphology that Ameiva is a more primi- 7. The musculature. tive genus than Cnemid phonis. Our observations of The greatest myological variation appears to osteological and myological structures which are be centered around the anterior segment of the seemingly of paleotelic significance also support this ventral musculature. The mylohyoideus com- conclusion.

It is to be noted that the terminology of this muscle has not been determined in the literature. The name of a similarly placed mammalian muscle is temporarily adopted until complete homologies can be determined. 39

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of western Mexico related to Cnemidophonis sacki. Bui- Novitates. 2235 : 1-49. INFORMATION FOR CONTRIBUTORS

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