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AMERICAN MUSEUM Novitates PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, N.Y. 10024 Number 3045, 24 pp., 13 figures, 1 table July 27, 1992

Estesia mongoliensis, a New Fossil Varanoid from the Late Cretaceous Barun Goyot Formation of Mongolia1

MARK A. NORELL,2 MALCOLM C. McKENNA,3 AND MICHAEL J. NOVACEK3

ABSTRACT A new lizard from the Late Cretaceous Barun minotus and Saniwa. Although the phylogenetic Goyot Formation was collected during the 1990 relationships among these taxa are uncertain, pre- joint Mongolian American paleontological expe- liminary analysis suggests that the new taxon is dition to the Gobi Desert, Mongolia. This lizard the sister group to Lanthanotus and Varanus. Fur- is referable to a clade containing the extant genera ther, it displays the unusual feature oflongitudinal Lanthanotus, Heloderma, and Varanus, as well as grooves on the teeth, identical to the grooves used several poorly known extinct taxa including Cher- for venom conduction in Heloderma.

INTRODUCTION One of the great Mesozoic and Tertiary worowska and Dovchin, 1968). Among these fossil-producing regions in the world is the are Cretaceous mammals and exquisitely Gobi Desert ofMongolia. Since their discov- preserved dinosaurs. Often overlooked, re- ery by field parties ofthe American Museum mains of lizards are among the most numer- in 1923, the Mesozoic beds from this region ous fossils encountered at some localities. have produced spectacular skeletons offossil Mongolian lizard fossils have been de- vertebrates (see Andrews, 1932; Kielan-Ja- scribed by Gilmore (1943) (from specimens

' This is contribution no. 1 of the Mongolian-American Museum Paleontological Project. 2 Assistant Curator, Department of Vertebrate Paleontology, American Museum of Natural History. 3 Curator, Department of Vertebrate Paleontology, American Museum of Natural History. Copyright © American Museum of Natural History 1992 ISSN 0003-0082 / Price $3.80 2 AMERICAN MUSEUM NOVITATES NO. 3045

Fig. 1. The type skull of Estesia mongoliensis. collected by the American Museum Central comparative description of this new taxon Asiatic expeditions) and Borsuk-Bialynicka and place it in a phylogenetic context. Com- (1984) and Sulimski (1972, 1975, 1978) (from ments regarding its explicit phylogenetic re- specimens collected by the Polish-Mongolian lationships are preliminary until a detailed expeditions). Here, we describe a new fossil reanalysis of the relationships among living lizard collected in June 1990, near Khulsan and fossil anguimorphs is accomplished. In in the Barun Goyot Formation by a field party the following discussion, nomenclatural ter- from the Mongolian Academy ofSciences and minology follows Pregill et al. (1986), where the American Museum of Natural History the varanoids include descendants ofthe last (fig. 1). This specimen, a nearly complete common ancestor of Heloderma, Lanthan- skull, displays features that may aid in de- otus, and Varanus, and Varanidae is restrict- ciphering the relationships among angui- ed to the descendants of the last common morph lizards. ancestor of Lanthanotus and Varanus. The Such complete specimens of fossil lizards morphological terminology follows Oelrich are generally rare. Where they exist, phylo- (1956) and Mertens (1942). genetic study is often hampered by a lack of detailed knowledge of extant taxa, making both determination ofcharacter polarity and INSTITUTIONAL ABBREVIATIONS the choice of appropriate outgroup taxa dif- AMNH American Museum of Natural His- ficult. Among lizards phylogenetically affili- tory ated with the taxon described herein (the Va- RE Collection of Richard Etheridge ranoidea), significant progress in resolving MAN Collection of Mark Norell relationships has been accomplished (Riep- MAS Mongolian Academy of Sciences pel, 1980; Gauthier, 1982; and Pregill et al., 1986). Nonetheless, much more work, in- LOCALITY, GEOLOGIC SETTING, AND cluding development of a phylogeny within HISTORICAL BACKGROUND the Varanidae, a detailed analysis ofSaniwa, and a comprehensive review of "necrosau- In 1990, after an absence ofnearly 60 years, rids" is needed. the American Museum of Natural History Our purpose is to provide a diagnosis and resumed exploration in outer Mongolia 1992 NORELL ET AL.: ESTESIA MONGOLIENSIS 3

Mongolian People's Republic Expedition Routes Mongolian - American

Roy Chapman Andrews - - - - Mongolian- Polish.

Fig. 2. Map of Mongolia, showing routes of American Museum Central Asiatic Expedition, the Polish-Mongolian Expedition, and the Mongolian-American Museum Expedition of 1990.

(Mongolian People's Republic until 1991; complete, but badly weathered ankylosaurid now simply Mongolia), in collaboration with skeleton, and several skulls of small lizards. the Mongolian Academy of Sciences. A re- The specimen was collected in the Barun connaissance of south-central Mongolia was Goyot Formation (Gradzinski and Jerzykie- undertaken in the early summer of 1990 (fig. wicz, 1972; Efremov, 1950, 1954, 1955). Ex- 2). During this reconnaissance, the field party posures at the locality are orange pink to light composed of Dr. Demberelyin Dashzeveg of brown, cross bedded and poorly indurated the Mongolian Academy ofSciences, and Mal- sands, with occasional small pebbles. These colm McKenna, Mark Norell, and Michael beds have been considered Late Cretaceous, Novacek of the American Museum of Nat- middle Campanian in age, based on multi- ural History visited the locality of Khulsan, tuberculates (Kielan-Jaworowska, 1974). explored in 1965 by the Polish-Mongolian "Comparative studies of dinosaurs and Expeditions, although fossils were not found mammals" (Gradzinski et al., 1977) suggest there until 1970 (fig. 3). The Khulsan locality that the Barun Goyot Formation is younger yielded a well-preserved skull and mandibles than the Djadokhta Formation at the Flam- and part of a front leg of a large varanoid ing Cliffs locality (Berkey in Granger and lizard in addition to specimens of other liz- Gregory, 1923). Lillegraven and McKenna ards and dinosaurs. The varanoid specimen (1986), however, argued that "the Djadokhta lay in a steep cliff face about 3 km down- and Barun Goyot formations are approxi- stream from the 1971 Polish-Mongolian Ex- mately equivalent in age, respectively, to the pedition's Khulsan camp (Gradzinski and older and younger parts of the North Amer- Jerzykiewicz, 1972). Also recovered at this ican Judithian." These authors stress that de- site were associations ofdinosaur eggs, a skel- termination ofabsolute ages and faunal stages eton of Protoceratops, the skull of a nearly is tenuous. Correlation based on higher taxa 4 AMERICAN MUSEUM NOVITATES NO. 3045

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Fig. 3. Map ofthe general region of Khulsan showing the locality where the specimen was collected. Modified from Gradzinski and Jerzykiewicz (1972). 1992 NORELL ET AL.: ESTESIA MONGOLIENSIS 5 of dinosaurs and mammals is difficult, no from the border of the suborbital fenestra radiometric or magnetostratigraphic evi- (Pregill et al., 1986). Can be differentiated dence is available, and the beds do not in- from all other varanoids by the following tertongue with any known fossiliferous ma- combination of derived characters: venom rine sediments (Lillegraven and McKenna, grooves on the teeth, and a lack of cranial 1986). osteoderms. Estesia mongoliensis is unique among squamates in possessing an extensive SYSTEMATIC PALEONTOLOGY convex surface medial to the posterior ridge on the posterior surface of the quadrate. REPTILIA COMPARATIVE DESCRIPTION OF HOLOTYPE: SAURIA The skull is a well-preserved cranium of an adult individual. There is no trace of free or LEPIDOSAURIA fused osteoderms accompanying the speci- SCLEROGLOSSA men. The roof of the skull, especially the parietal and the frontals, may have been sculp- ANGUIMORPHA tured, or the crenulated surface may be an VARANOIDEA effect of weathering. The lateral surfaces of the maxillae and the dentaries are smooth as Estesia mongoliensis, new taxon4 in Varanus. Figures 4-7 The right side of the skull is badly weath- HOLOTYPE: M 3/14; a skull and mandibles. ered and only a few elements remain. The ETYMOLOGY: Estes (proper name), and posterior region (i.e., braincase) is crushed; mongoliensis, geographic location, after however, the left side ofthe skull and the left Richard Estes in honor of his timeless con- mandible are nearly complete. Lateral sur- tributions to the study of fossil lizards. faces of the skull and dentaries are smooth, LOCALITY OF HOLOTYPE: Lizard Hill, Khul- whereas the skull roof is covered with fine san. South Gobi Aimak, Mongolia. striations, somewhat like those found in large 43029'19"N, 101°08'44"E (fig. 1). 4741' MSL. adult Varanus. The occipital region ofEstesia DATE COLLECTED: June 1990, by M. C. Mc- mongoliensis is crushed and the fragmentary Kenna, M. A. Norell, and M. J. Novacek occipital condyle has been rotated into the (AMNH), and D. Dashzeveg (MAS). braincase. DIAGNOSIS OF NEW TAXON: Referable to the Varanoidea on the basis of the following OPENINGS OF THE SKULL derived characters: nasal and maxillary bones Large, protracted nares are characteristic with or no contact, little large subolfactory ofEstesia mongoliensis and other varanoids. processes of the frontal, a lack dental re- of The nares reach posteriorly almost to the an- sorption pits, sharply pointed plicidentine terior margin of the orbits. Reminiscent of teeth, a long vomer with narrow palatal the Varanidae is the large circular orbit. The shelves, and a short, wide palatine that contacts the ectopterygoid to exclude the maxilla supratemporal fenestrae are small. On the palatal surface, the suborbital fenestra is short and elliptical. The exochoanal fenestra is long 4Following Queiroz and Gauthier (1990 and ms.) and thin, extending posteriorly to the back higher taxonomic categories are not recognized. Besides of the tooth row. other difficulties discussed in these papers, recognition The pyriform recess is nar- of taxonomic categories implies a sort of equivalence row anteriorly and extends to the level ofthe between categories ofsame rank. This extension includes fourth posterior maxillary tooth. the categories included in the Linnean binomial. The binomial Estesia mongoliensis, therefore, should not be CRANIAL BONES considered a strict Linnean binomial composed of a species (E. mongoliensis) in the genus Estesia. Rather, Es- The premaxilla is composed of a dentig- tesia mongoliensis is a two-part taxonomic name. Ifthis erous maxillary process, a nasal arch, and a is troublesome to some readers, the name Estesia mon- vomerine process. Anteriorly the premaxilla goliensis can be considered equivalent to a Linnean bi- is thin dorsoventrally. In fact, it is so thin nomial, however, the senior author makes no such claim. that there is no flat anteriorly directed surface 6 AMERICAN MUSEUM NOVITATES NO. 3045

2cm

Fig. 4. Dorsal view of Estesia mongoliensis. For abbreviations see Appendix 1. dorsal to the tooth row and ventral to the narial branches ofthe maxillary arteries (Oel- floor of the narial chamber. The premaxilla rich, 1956). is not pierced anteriorly by medial ethmoidal Ventrally, the vomerine process is short, foramina, a condition also seen in Heloderma as in Heloderma and Lanthanotus; thus the and some Varanus (e.g., Varanus gouldi). The premaxilla is wider than long. A reflected nasal process is long and tapers posteriorly, winglike incisive process lies along the mid- contacting the nasal arch between the paired line posteroventrally. As in Lanthanotus, nasal elements. The nasal process is trian- Heloderma, and some Varanus, the premax- gular in cross section, with ventrally directed illary-maxillary aperture (between the max- apex. Whether the nasal arch of the premaxilla and the premaxilla) and the premaxillary illa contacts the frontal beneath the nasals foramen (lateral to the incisive process) are cannot be determined. Posterolateral to the absent. Both of these are found in Varanus base of the nasal process lie small foramina (fig. 8B). The dentigerous process bears po- for the medial ethmoidal nerves and the sub- sitions for nine teeth. 1992 NORELL ET AL.: ESTESIA MONGOLIENSIS 7

angle of the naris. Therefore, a nasal-maxillary contact, ifpresent, was not extensive and lay at the posterior angle ofthe naris. In Helo- derma this condition is sometimes variable on opposite sides of the same specimen. The septomaxilla of Estesia mongoliensis, as in Varanus, is elaborate. The bone lies on top of the vomers and contacts the septo- maxillary branch of the maxilla anteriorly. Dorsally the septomaxilla contacts the premaxillary branch of the nasal on the inter- narial bar. The dorsal surface of the septomaxilla is elaborated with a series of crests, the largest of which is a median ridge that lies on the medial edge ofthe bone. A prominent boss lies anteriorly, dorsal to a ventral concavity. Along the median edge, a canal runs along the long axis of the bone. The prefrontal is very large. Dorsally it may form the posterior angle ofthe naris, excluding the maxilla from contact with the nasal. Above the orbit the prefrontal forms the anterior two-thirds of the orbital border, contacting the postorbital-postfrontal compound bone above the orbit as in Heloderma and Lanthanotus. The dorsal surface is somewhat concave laterally, forming a supraciliary ridge that runs anteriorly onto the rostrum. The anterior wall of the orbit is formed by the palatine process of the prefrontal. The palatine process also forms the anterior part of the subolfactory process (fig. 9). Ventrally the prefrontal contacts the palatine. The orbi- tonasal fenestra was apparently very small. 2cm Palpebrals are not preserved on the holotype ofEstesia mongoliensis. In Varanus the Fig. 4-(Continued). palpebral lies in a large prefrontal fossa between the lacrimal and the prefrontal on the anterodorsal orbital rim. The presence of a The nasal is long and thin, contacting the similar fossa in Estesia mongoliensis suggests frontal posteriorly and the nasal process of that large palpebral bones may have been the premaxilla anteriorly. The nasal process present. of the premaxilla enters an anterior notch The frontal is paired and parallel-sided, between the nasal bones; the nasal forms the with a posterolateral postorbital process. Lat- posteromedial border of the nares. Posteri- erally the frontal is excluded from the supra- orly, lateral to the midline on the intemarial orbital rim by contact of the prefrontal and bar, the nasal thins and overhangs the narial the postorbital. The anterior articulation of chamber. The nasals are not fused into a sin- the frontal with the nasal is not preserved. gle element along the midline as in Varanus Ventrally, a large subolfactory process is and adult Lanthanotus. Posteriorly the nasals present; however, unlike in varanids and he- are divided by an anterior process ofthe fron- lodermatids, the processes fail to meet either tal. The frontonasal suture is posterolaterally anteriorly or posteriorly to form an osseous transverse. This suture ends at the posterior subolfactory canal. Instead the subolfactory 8 AMERICAN MUSEUM NOVITATES NO. 3045

2cm

Fig. 5. Palatal view of Estesia mongoliensis. For abbreviations see Appendix 1. processes are intermediate between the more on the lateral surface ofthe parietal. The post- primitive anguid condition of subolfactory orbital ramus is short and tapers laterally. It processes that do not approach each other, contacts the anterior surface of the jugal's and the derived condition seen in the Varan- postorbital process. The supraorbital ramus oidea (fig. 9). is very broad and extends above the orbit to In Estesia, as in other varanoids, the post- contact the prefrontal. Posteriorly, the su- orbital and postfrontal form a single bone. pratemporal and parietal rami form a wide, This compound bone has four rami: an an- gently laterally concave dorsal surface before terior supraorbital ramus that contacts the they separate. The supratemporal ramus is prefrontal above the orbit, a lateral postor- wide and longer than the parietal ramus, ex- bital ramus that meets the jugal to form a tending about one-third the length ofthe su- postorbital bar, a supratemporal ramus that, pratemporal fenestra. Posteromedially the with the squamosal, forms the supratemporal supratemporal ramus is very thin and over- arcade, and a short parietal ramus that lies hangs the supratemporal fenestra. The lateral 1 992 NORELL ET AL.: ESTESIA MONGOLIENSIS 9

pm 1983) and Heloderma. Laterally, the parietal is concave; the temporal musculature attached to a concave surface on the lateral side of the bone. Posteriorly, a long supratemporal process forms the posterior border of the supratemporal fenestra. Near its posterior end the supraorbital process is hook shaped and lies in a groove in the supratemporal. The posterior end ofthe supraorbital process forms a small knob. The supratemporal of Estesia lies on the lateral surface of the supratemporal process of the parietal. The supratemporal is almost as broad as the supratemporal process of the parietal and extends anteriorly almost to the margin of the posterior part of the parietal table. The supratemporal is not visible in dorsal view; it fails to reach the dorsal margin ofthe parietal and the supratemporal process ofthe parietal is ventrally oriented where the supratemporal overlaps it. Posteriorly the supratemporal underlies the ventral surface of the parietal's supratemporal process and is also exposed slightly on the supraoccipital process' medial surface. Here, the supratemporal is wedged between the parietal and the paroccipital process of the exoccipital. Lat- erally, the supratemporal is wedged between the squamosal and the posterior part of the parietal's supratemporal process. Ventrally the supratemporal isolates the supraorbital process of the parietal from the quadrate's cephalic condyle. In lateral view the maxilla of Estesia is 2cm triangular. The bone forms most of the floor Fig. 5-(Continued). of the olfactory chamber and borders the anterolateral and lateral margins of the naris. The narial margins are rounded and smooth. surface of the supratemporal ramus is con- Anteriorly the maxilla contacts the premax- tacted by the squamosal. How much of the illa and is dorsoventrally thin. The anterior lateral surface ofthe postorbital contacted the floor of the narial chamber is flat. Just pos- squamosal cannot be determined because of terior to the premaxillary narial arch, in the poor preservation. The parietal ramus abuts narial chamber, a medial process ofthe max- the anterolateral margin of the parietal and illa forms the posterior wall of the maxillo- forms the anterior angle ofthe supratemporal premaxillary aperture. Posteriorly this fenestra. process is elevated and contacts the septo- The parietal is hourglass shaped, with an maxilla. This elevated area continues later- extensive parietal table. Anteriorly it contacts ally as a small ridge posterior to which arises the frontals. A pineal foramen is absent, al- a single anterior inferior alveolar foramen. though a pineal fossa is present posteriorly The nasal process emanates from the bone just anterior to the angle ofthe supratemporal posteriorly. It contacts the prefrontal, the lac- processes, more or less in the same position rimal, and the jugal in a dorsoventral diag- as it is in Telmasaurus grangeri (see Estes, onal suture. A row of large mental foramina 10 AMERICAN MUSEUM NOVITATES NO. 3045

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Fig. 6. Left lateral view of Estesia mongoliensis. For abbreviations see Appendix 1. lie dorsal to the tooth row and posteriorly the maxilla anterolaterally, and the jugal ven- maxilla overhangs the tooth row. On the pal- trally. The posterior margin of the lacrimal atal surface the maxilla contacts the premax- forms the anterior rim and wall of the orbit illa and vomer anteriorly and the ectopter- and bears a pronounced posterior spine as in ygoid and palatine posteriorly, and forms the living Varanus. In Varanus, Lanthanotus, and lateral margin of the long and thin extra- Saniwa the lacrimal is perforated by a pair choanal fenestra. Lateral to the tooth row the ofposterior lacrimal foramina (Gabe and St. maxilla forms a wide palatal shelfthat tapers Girons, 1976). In Varanus the larger dorsal posteriorly. Anteriorly, just posterior to the foramen lies on the margin of the lacrimal premaxillary contact, the maxilla and the vo- and the prefrontal, whereas the ventral fo- mer border the incisive foramen. Eleven tooth ramen, usually smaller, is completely en- positions were present on the maxilla. closed by the bone. In Lanthanotus the fo- The lacrimals are trapezoidal and contact ramina are equal in size and lie entirely within the prefrontal dorsally and medially, the the lacrimal (contra Rieppel, 1980). Estesia 1992 NORELL ET AL.: ESTESIA MONGOLIENSIS I I

thanotus and Heloderma. The jugal apparently did not form any of the supratemporal arcade, yet on the lateral surface of the postorbital it may have contacted the postorbital process of the squamosal. The squamosal ofEstesia is a thick, heavy bone that, as in Varanidae, forms most ofthe supratemporal arcade. Anteriorly it contacts the lateral surface of the postorbital-postfrontal in a groove along that bone's lateral edge. Posteriorly the bone is much heavier than in Varanus, although it is similarly hooked and contacts the dorsal surface ofthe quadrate. The quadrate ofEstesia is very large. Nei- ther the articular nor cephalic condyles are preserved. A large outer conch (absent in Varanus) forms the tympanic crest. The anterior surface of the quadrate is extensive; wider ventrally than dorsally. A median longitudinal (dorsoventral) depression and a lateral reflected edge form an undulating surface. The posterior crests divide the posterior surface medially. Lateral to the posterior crest lies a large concave depression that tapers ventrally to the articular condyle. Medial to the posterior crest, the posterior surface of the quadrate forms an extensive convex surface. The vomer is long and thin and articulates with the palatine at the level of the last max- E 0 illary tooth. The vomers are medially conflu- c0J ent for about half of their length; they lack the lateral processes of Lanthanotus. As in Varanus, small crests are present posteriorly Fig. 6-(Continued). on the ventral surface; however, the vomers are keeled for their entire length, lacking the ventral surface found in other varanoids. mongoliensis displays the primitive condi- Where the vomers meet anteriorly a deep fos- tion of a lacrimal that is perforated along the sa is present. On the anterior wall ofthis fossa suture with the prefrontal by a single slitlike lies a pair of vomerine foramina. Anteriorly lacrimal foramen (fig. 10). the vomer meets the incisive process of the The jugal forms the entire ventral and pos- premaxilla. A small vomeronasal foramen is terior orbital border. In lateral view it is dor- present between the vomer and the maxilla, soventrally concave, wide anteriorly, and ta- lateral to which lie the lacrimal crests that pered posteriorly. This lateral concavity forms are similar to those found in Varanus. Lat- an everted rim on the anteroventral orbital erally the vomer forms the medial border of border. Inside the orbit, the jugal is broad the exochoanal foramen. The dorsal surface and contacts the ectopterygoid medially. On of the vomer is hidden inside the cranium. its ventral surface is a large fossa, also present The palatines are longer than wide as in in Heloderma. Posterodorsally thejugal thins other varanoids. The palatine is "Y"-shaped and contacts the postorbital-postfrontal to with anterior vomerine and maxillary pro- form a complete postorbital bar as in Lan- cesses and a posterior pterygoid process. Dor- 12 AMERICAN MUSEUM NOVITATES NO. 3045

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.,i, *_ sft 't " .;'i; t' s- .- '.''5^ f;} ,., .,, iF -., '.t I.,, o.FtX 1% "-;val. .,* X M<-'e E **i c1JC\, g ds, { _ ,t '.. 4 Fig. 7. Dorsal and labial view of Estesia mongoliensis. For abbreviations see Appendix 1. sally the ascending prefrontal process con- is perforated by a conspicuous infraorbital tacts the prefrontal, and the lacrimal andjugal foramen. dorsolaterally. The maxillary process extends The pterygoid is "Y"-shaped with large anteriorly to the level of the second tooth, transverse and palatine processes anteriorly, unlike in Heloderma where the entire tooth and a long thin quadrate process posteriorly. row lies anterior to the palatine. As in He- The ectopterygoid process is ventrally con- loderma and in juvenile Varanus and Lan- cave, with an elevated lateral margin forming thanotus, the vomerine process is shorter than a ridge similar to the condition in Heloderma. the maxillary process. Between the maxillary Dorsally the pterygoid overlies the ectopter- and vomerine process a small ventral fossa ygoid, as in Heloderma, but not as in Varanus is formed by a shelf of bone overhanging the where the pterygoid lies in a notch of the crux, ventral to contact with the lacrimal. ectopterygoid anteriorly. The ectopterygoid The dorsal surface forms the anteroventral process fails to reach the ectopterygoid-jugal floor of the orbit. Anteriorly, immediately contact, as it does in Heloderma. The trans- ventral to contact with the lacrimal on the verse process extends further anteriorly than anteroventral wall ofthe orbit, the pterygoid the ectopterygoid process. A large, rugose, 1992 NORELL ET AL.: ESTESIA MONGOLIENSIS 13

C D terygoid forks into a short, heavy, ventral pterygoid process and a long, thin, dorsal process. The ectopterygoid process of the pterygoid articulates into this fork and a large palatine process covers most of its surface. The bones of the braincase are very fragmented and most are not preserved. Those present are featureless because of crushing and distortion. Nevertheless, fragments ofthe basioccipital, the exoccipital, and the opis- thotic are preserved in a jumbled mass inside of the braincase area.

MANDIBLE The better preserved left mandible is fragmentary ventrolingually. The retroarticular process is fragmented posteriorly. The right dentary is only preserved anteriorly. The mandible is long, thin, and smooth (fig. 7). The entire lower jaw is curved, especially far anteriorly and just anterior to the articular fossa. Both ventral surfaces are se- verely weathered. The lateral surface of the dentary is smooth and contains a row offour large mental foramina. Lateral to the tooth row, a thin lamina of bone forms a shallow dental parapet. Posterior to the tooth row, *the dentary is robust, dorsoventrally concave, and long relative to that of other varanoids, being three-fourths as long as the tooth-bearing segment ofthe dentary. A small coronoid process fills a groove on the anterior Fig. 7-(Continued). margin of the coronoid. This process is developed to the same degree as in Varanus but not so large as in Heloderma. The loose con- elevated platform is prominent ventrally. nection between the dentary and the poste- There is no evidence that pterygoid teeth were rior elements and the groove on the anterior present in life. The quadrate process is long, coronoid margin suggests that kinesis along thin, and tapers posteriorly. It is ventrally this margin was possible. oriented and its medial surface is dorsoven- Only a small fragment of the left splenial trally concave. The dorsal surface ofthe pter- is preserved and no features of interest are ygoid is not visible except anteriorly as a con- apparent. The coronoid is a large element vex floor of the orbit. situated dorsal to the surangular. Anterior to The ectopterygoid is robust, as in Heloder- the low coronoid eminence lies a short den- ma, with anterior maxillary and palatine pro- tary process. Labially the dentary process is cesses. The palatine process abuts the pala- not extensive dorsoventrally; however, on the tine, excluding the maxilla from participation lingual surface the dentary process is exten- in the suborbital fenestra. However, unlike sive and platelike with a tongue that underlies Heloderma, the anterior palatine process does the splenial. Lingually just ventral to the cor- not extend anteriorly between the maxilla and onoid eminence is a large excavated area. the palatine. Anterolaterally, a large maxil- Posteriorly this area is bordered dorsally by lary process is present. Posteriorly the ectop- the extensive surangular process of the cor- 14 AMERICAN MUSEUM NOVITATES NO. 3045

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Fig. 8. Palatal views of (A) Heloderma suspectum (MAN 9), (B) Varanus komodoensis (AMNH 37912), and (C) Lanthanotus borneensis (RE 1445). onoid. Laterally, a vertical ridge runs ven- In squamates generally the articular forms trally from the coronoid eminence, posterior the articular fossa and is the bony ossification to which lies the triangular lateral exposure of the posterior end of Meckel's cartilage. In of the surangular process. Estesia mongoliensis the articular is appar- The angular is extremely fragmented, rep- ently not present. Because the mandible was resented only by splinters of bone. The sur- found in articulation with the quadrate, it is angular forms most of the lateral and pos- reasonable to believe that this element is in teroventral surface ofthe mandible posterior fact lacking rather than an artifact of pres- to the coronoid. The surangular is large and ervation. curved, and the posterior part of the mandible is arch shaped. A large posterior surangular foramen pierces the surangular an- TEETH terolateral to the articular fossa and emerges The teeth of Estesia mongoliensis are typ- medially in the mandibular fossa. An anterior ical of varanoids in being plicidentine, and surangular foramen is not present. recurved with sharp points (Pregill et al., The prearticular is exposed on the lingual 1986). The tooth bases are expanded and surface of the mandible; in lingual aspect it tooth replacement occurs from the back; con- forms much of the posteroventral surface of sequently resorption pits are not present. The the mandible. It is robust dorsally and forms ventromedial surface of each tooth is perfo- the lateral medial border of the mandibular rated by a small nutrient foramen. As in fossa. Posteriorly it forms the flat and thin Heloderma, the premaxillary teeth (of which (although crushed) retroarticular process. there are nine) are markedly smaller than the 1992 NORELL ET AL.: ESTESIA MONGOLIENSIS 15 A B

Fig. 9. The subolfactory processes of (A) Elgaria multicarinatus (MAN 7), (B) Estesia mongoliensis, (C) Varanus salvator (MAN 48), (D) Lanthanotus borneensis (RE 1445), and (E) Heloderma suspectum (MAN 9).

cheek teeth. The maxillary and dentary teeth lated to the transmission of venom with the are widely spaced. There are positions for saliva. Pregill et al. (1986) were cautious in nine maxillary teeth. The left dentary con- suggesting that this groove was used as a ven- tains five tooth positions; the right dentary om-conducting structure in taxa closely re- is incomplete but has four teeth. As in Helo- lated to Heloderma, because, obviously, this derma, the largest teeth in the dentary tooth cannot be observed in fossil taxa. However, row occur in the middle of the tooth row the correlation is impressive and it is possible (positions 3 and 4), giving the tooth row an that Estesia mongoliensis shared with Helo- arched aspect [compare fig. 8 in Pregill et al. derma the ability to conduct salival venom (1986) with fig. 1 1 here]. through its grooved teeth. The most interesting feature of the teeth is the presence ofdeep longitudinal grooves that run the entire length of each tooth on both DISCUSSION the anterior and posterior tooth surfaces (fig. Estesia mongoliensis displays a suite of 1 1). These grooves are also present in extant primitive and derived characters that invite Heloderma and its close helodermatid rela- comparison with other anguimorphs. Yet it tives. For instance, in Paraderma bogerti "an is difficult to evaluate these similarities in a incipient groove is present on the antero- phylogenetic context until a detailed analysis medial margin near the base" ofthe best pre- of additional taxa is completed. These taxa served tooth (Pregill et al., 1986). In extant include the purported varanines from the Heloderma these grooves are functionally re- Cretaceous of Mongolia Telmasaurus gran- 16 AMERICAN MUSEUM NOVITATES NO. 3045

geri and Saniwides mongoliensis, the Creta- ceous Mongolian putative lanthanotine Chermonotus longifrons, the "necrosaurids" Gobiderma pulchrum, Proplatynota longiros- trata, and Parviderma, and the poorly studied ,4t1,° prfA North American taxon Saniwa. The marine "platynotan" lizards (e.g., mosasaurs and ai- gialosaurs) also need be considered. Never- theless, an initial approximation of the phylogenetic position ofEstesia mongoliensis can OF be attempted. The analyses of the Varanoidea by Pregill et al. (1986) considered 80 characters. These characters include skeletal features, charac- Re- B D/PLF ters of the soft anatomy, and behavior. prf sults oftheir analysis indicate that Lanthano- tus is the sister group to a monophyletic Varaninae. These taxa compose the Varani- pi dae, whose sister group is the Helodermati- dae, represented by the fossil taxa Parader- ma, Lowesaurus, and Eurheloderma and the OF extant taxon Heloderma. This phylogeny is similar to the one proposed by McDowell and Bogert (1954) and Rieppel (1980) for this subset of anguimorph taxa. C PLF The characters of Pregill et al. (1986) were scored for the holotype of Estesia mongo- prf liensis. These characters are listed in appendix 1 and a matrix showing their distribution pi within the group is provided in table 1. Again, because our analysis is considered preliminary, no modifications to the codings or char- IOF acter descriptions ofPregill et al. (1986) were included in this paper. Characters were an- alyzed using David Swofford's PAUP 3.OL for the Macintosh. The exhaustive search op- trees were ex- D tion indicated that all possible DPLF amined. Characters were polarized using the prf polarities of Pregill et al. (1986). These polarities were enforced by using the ancestor VPLF function (all zero) to root the tree. Until a detailed analysis of additional taxa can be p1 completed Pregill et al.'s (1986) diagnoses for clades within the Varanoidea and classifica- tion are not modified. The analysis yielded a unique tree of 71 Fig. 10. The anterior orbital wall in (A) Estesia steps. This tree (fig. 12A) indicated the basic mongoliensis, (B) Lanthanotus borneensis (RE of et al. (1986), Rieppel 1445), (C) Heloderma suspectum (MAN 9), and topology Pregill (D) Varanus komodoensis (AMNH 37912). The (1980), and McDowell and Bogert (1954) in posterior lacrimal foramen is primitively single in advocating a sister-group relationship be- Estesia mongoliensis and Heloderma suspectum. tween Lanthanotus and Varanus (the Varani- The derived paired condition is seen in Varanus dae), with helodermatids as their sister group and Lanthanotus borneensis. (the Varanoidea). Estesia mongoliensis is the 1 992 NORELL ET AL.: ESTESIA MONGOLIENSIS 17

5mm

st.~~~~~~~~~~~~~~~A

5mm

Fig. 11. The mandibular teeth of (A, B) Estesia mongoliensis and (C) Heloderma suspectum (MAN 9). Notice the enlarged medial teeth and the well-developed grooves. Possibly these grooves functioned as a poison delivery system. sister group of the Varanidae. Four derived (fig. 1 2B), 3 steps longer than the shortest tree characters (characters 4, 5, 18, and 48) that and a retention index of 0.653. This tree in- could be scored in Estesia mongoliensis sup- dicates a sister-group relationship between port this grouping. All ofthese characters are helodermatids and Estesia mongoliensis. Two optimization independent. That is, the same characters (numbers 30 and 14) that can be characters support this node no matter what scored for Estesia mongoliensis unambigu- optimization criterion is implemented. These ously support the Estesia + helodermatid characters include the derived conditions of grouping. These characters are the insertion nasal and maxillary bones that fail to contact, of the temporal musculature on the ventral a nasal process of the maxilla that rises from surface of the parietal and presence of well- the posterior aspect of the maxillary, a nar- defined "venom" grooves on the teeth. Such row supratemporal process of the parietal, grooves are widespread among helodermat- and no osteoderms fused to the skull. ids and lizards of necrosaurian grade. They The next closest tree has a length of74 steps are most developed in extant Heloderma; cl-o-- o 0 0 No .--t- 4--cK-

N IC c-o- - - cb~ --K -b c-o vot- o-- cK. £

- o h o^c-. -- co.- K (ON O--eNOOo_ - .__ - 0 00 0C) o - - o --q 0 -- t

nnks-D en _0 s~~~~~~~~~~~~~~r C- b-

t 1° ., 0 - 0 I-1--0--1 Qa@txo--- Y 1 6 - ix !- : Q :~~~~~~~~~~~~~~~~~~~tnCl- ^ oo -

t : E,;$:°x 0 ef~~~~~~~~~~~~~~~~~~~~~~>0 - 00--0-C'.~~~~~~~~t-o cK I - - -0Io--0s -I1 1--- ~~~00 -~~~~~i0 ~~~~~~~ 0 - 00 0 000 -~~~~~~~~~~~~~l- LL) C'

N ~~~~~~~~~~~~Nr ~~N0

0 --4-4 ci --

-.4-4~~~~ ~ ~ ~ ~ ~ ~ ~~~~~~~c- -

C:0-C ---C: -4

c o~~----~ ~ ~ ~ ~ c0-

0 0 Itt~~~~~~~ 00~

*~~~ ~ ~ ~ ~ ~ ~ * - ~~~CS*q > >~~~- 1992 NORELL ET AL.: ESTESIA MONGOLIENSIS 19

NECROSAURIDAE *

A HELODERMA 0 00

a,- N LANTHANOTUS

l_ VARANIDAE N r- Nr- ESTESIA

Im' c- __t " :.. _ _t I NECROSAURIDAE *

C-- I -__ .

'l -O__ - B HELODERMA I _ I_l cl. .-_ - _b.- ESTESIA

St LANTHANOTUS

m VARANIDAE >1. d- - cl. Fig. 12. (A) Minimum length tree for the data presented in table 1, (B) next shortest tree for the data presented in table 1.

however, they are also well developed in fossil relatives. The presence of venom grooves in Estesia mongoliensis is curious and, if the phylogeny in figure 1 2A is corroborated, one C4,@ _ _ possible optimization ofthis character is that "venom grooves" are primitive for the Va- ranoidea. A difficulty with the minimum length tree is that Necrosauridae*, considered a basic

0 '0 taxon by Pregill et al. (1986), is not demon- 0 r. strably monophyletic (Estes, 1983; Estes et I~ ~3 '0 Hd o 'rt -zO- al., 1988). The asterisk following Necrosaur- idae* is an indication that there is no evidence for or against monophyly, viz., a meta- taxon of Donoghue (1985) and Gauthier et al. (1 988a). Ifnecrosaurs are paraphyletic relative to other varanoids, local character polarities within higher varanoids will be mod- 20 AMERICAN MUSEUM NOVITATES NO. 3045

Fig. 13. A reconstruction of Estesia mongoliensis preying on a nest of Protoceratops. ified. For example, in the minimum length tesia mongoliensis synapomorphy of osteo- tree described above (fig. 12A), a synapo- derm loss. Until a hypothesis of monophyly morphy uniting Estesia mongoliensis with for Necrosauridae* can be demonstrated or Varanidae is the lack of osteoderms fused to this grouping is abandoned due to paraphyly, the skull. Both conditions occur in the Nec- an interim solution to this difficulty is to prune rosauridae*; however, if Necrosauridae* is Necrosauridae* from the analysis. The re- paraphyletic, character polarity at this level sultant minimum length tree (exclusive of may be modified and osteoderms present in Necrosauridae*) is 17 steps shorter (length helodermatids may be deemed apomor- 54) than that in figure 1 2A and has a retention phic -thus invalidating the Varanidae + Es- index of 0.677. Eliminating Necrosauridae* 1 992 NORELL ET AL.: ESTESIA MONGOLIENSIS 21 from the analysis has no effect on tree to- manuscript and their comments are appre- pology or on the character evidence for an ciated. Estesia mongoliensis + Varanidae clade.

CONCLUSIONS REFERENCES The presence of an additional varanoid in Andrews, R. C. the Cretaceous of Mongolia is yet another 1932. The new conquest ofCentral Asia. New York: Am. Mus. Nat. Hist. indicator ofthe extensive Mesozoic radiation Borsuk-Bialynicka, M. ofthis group in northern Asia. Such high var- 1984. Anguimorphs and related lizards from anoid diversity in a single region is unpar- the Late Cretaceous ofthe Gobi Desert, alleled today. Extant varanoids are active, Mongolia. Results of the Polish Mon- highly visual, carnivorous lizards that often golian Paleontological Expeditions Part prey on small or juvenile animals and often 10. Palaeontol. Polonica 46: 5-105. raid the nests of birds (Pregill et al., 1986). Donoghue, M. J. In the immediate vicinity ofthe type locality 1985. A critique ofthe biological species con- ofEstesia mongoliensis, several aggregations cept and recommendations for a phy- (nests?) of small to logenetic alternative. Bryologist 88: 172- medium sized dinosaurs 181. were found. Estesia mongoliensis, like its Efremov, I. A. modern relatives, probably also preyed on 1950. Tafonomia i geologicheska letopis. Tr. similar organisms; it is interesting that other Paleontol. Inst. Akad. Nauk SSSR 24: Cretaceous varanoids (i.e., Saniwa) from the 178 pp. Judith River, Montana, have also been found 1954. Paleontologicheskie issledovania v in the direct proximity of dinosaur nests. Mongolsky Narodnoy Respublike Although the environmental reconstruc- (predvaritelnye rezultaty ekspediciy tion in figure 13 is tantalizing, the discovery 1946, 1948 i 1949 gg.). Tr. Mongol. ofEstesia mongoliensis is probably more im- Kom. Akad. Nauk SSSR 59: 3-22. portant because it will aid in deciphering re- 1955. Zakhoronenie dinozavrov v Nemegetu (Yuzhnaya Gobi, MNR). Vopr. Geol. lationships among higher anguimorph liz- Azii 2: 789-809. ards. By adding a new, excellently preserved Estes, R. taxon with unique character combinations 1983. Sauria Terrestria, Amphisbaenia. near the base of the varanid-helodermatid Handbuch der Palaoherpetologie, Part radiation, the phylogenetic position of frag- 1OA: 249 pp. Stuttgart: Gustav Fischer mentary, derived, and enigmatic taxa may be Verlag. resolved (Gauthier et al., 1988b). Estes, R., K. de Queiroz, and J. Gauthier 1988. Phylogenetic relationships within squa- mata. In R. Estes and G. Pregill (eds.), ACKNOWLEDGMENTS Phylogenetic relationships of the lizard families, pp. 119-282. Stanford Univ. We thank the Mongolian Academy of Sci- Press: Stanford, CA. ences for their help in organizing our collab- Gabe, M., and H. St. Girons oration. Official clearance for travel was ac- 1976. Contribution a la morphologie compa- quired with the help ofTjoran Achitsaikhan, ree des fosses nasales et de leurs annexes Mongolian representative to the United chez les lepidosauriens. Mem. Mus. Natl. Nations. The staff of the Institute of Verte- Hist. Nat., Paris, ser. A, 98: 1-106. brate Paleontology and Paleoanthropology Gauthier, J. A. provided gracious hospitality during our stay 1982. Fossil xenosaurid and anguid lizards in Beijing. Barbara Werscheck and Julie Tur- from the early Eocene Wasatch For- ner assisted in logistical preparation for the mation, southeast Wyoming, and a re- vision ofthe Anguioidea. Contrib. Geol., expedition. The figures were skillfully pre- Univ. Wyoming 21: 7-54. pared by Lorraine Meeker, Chester Tarka, Gauthier, J. A., R. Estes, and K. de Queiroz Mick Ellison, and Ed Heck. Darrel Frost, Greg 1988a. A phylogenetic analysis of Lepidosau- Pregill, and Olivier Rieppel carefully read the romorpha. In R. Estes and G. Pregill 22 AMERICAN MUSEUM NOVITATES NO. 3045

(eds.), Phylogenetic relationships of the pectinata (Iguanidae). Misc. Publ., Mus. lizard families, pp. 15-98. Stanford Zool., Univ. Michigan 94: 122 pp. Univ. Press: Stanford, CA. Pregill, G. K., J. A. Gauthier, and H. G. Greene Gauthier, J., A. G. Kluge, and T. Rowe 1986. The evolution of helodermatid squa- 1988b. Amniote phylogeny and the importance mates, with description of a new taxon of fossils. Cladistics 1988(4): 105-209. and an overview of Varanoidea. Trans. Gilmore, C. W. San Diego Soc. Nat. Hist. 21(11): 167- 1943. Fossil lizards of Mongolia. Bull. Am. 202. Mus. Nat. Hist. 81: 361-384. Queiroz, K. de, and J. Gauthier Gradzinski, R., and T. Jerzykiewicz 1990. Phylogeny as a central principle in tax- 1972. Additional geographical and geological onomy: phylogenetic definitions oftax- data from the Polish-Mongolian Pale- on names. Syst. Zool. 39(4): 307-322. ontological Expeditions. Results of the MS. Principles of phylogenetic taxonomy: Polish-Mongolian Palaeontological Ex- reorganizing the taxonomic system peditions Part 4. Palaeontol. Polonica around the central tenet ofcommon de- 27: 17-30. scent. Gradzinski, R., Z. Kielan-Jaworowska, and T. Rieppel, 0. Maryanska 1980. The phylogeny of anguinomorph liz- 1977. Upper Cretaceous Djadokhta, Barun ards. Basel: Birkhiiuser Verlag. Goyot and Nemegt formations ofMon- Sulimski, A. golia, including remarks on previous 1972. Adamisaurus magnidentatus n. gen., n. subdivisions. Acta Geol. Polonica 27(3): sp. (Sauria) from the Upper Cretaceous 281-318. of Mongolia. Palaeontol. Polonica 27: Granger, W., and W. K. Gregory 43-56. 1923. Protoceratops andrewsi, a pre-ceratop- 1975. Macrocephalosauridae and Polygly- sian dinosaur from Mongolia. Am. Mus. phanodontidae (Sauria) from the Late Novitates 225: 20 pp. Cretaceous of Mongolia. Results of the Kielan-Jaworowska, Z. Polish Mongolian Paleontological Ex- 1974. Multituberculate succession in the Late peditions Part 6. Palaeontol. Polonica Cretaceous of the Gobi Desert. Results 33: 25-102. ofthe Polish Mongolian Paleontological 1978. New data on the genusAdamisaurus Su- Expeditions Part 5. Palaeontol. Polon- limski 1972 (Sauria) from the upper ica 30: 23-44. Cretaceous of Mongolia. Results of the Kielan-Jaworowska, Z., and N. Dovchin Polish Mongolian Paleontological Ex- 1968. Narrative of the Polish Mongolian Pa- peditions Part 8. Palaeontol. Polonica leontological Expeditions 1963-1965. 38: 43-56. Results of the Polish Mongolian Pale- ontological Expeditions Part 1. Pa- laeontol. Polonica 19: 7-30. APPENDIX 1 Lillegraven, J. A., and M. C. McKenna Anatomical Abbreviations Used in Figures 1986. Fossil mammals from the "Mesaverde" Formation (Late Cretaceous, Judithian) AJO aperture for Jacobson's organ of the Bighorn and Wind River Basins, av vomerine aperture Wyoming, with definitions of Late Cre- DPLF dorsal posterior lacrimal foramen taceous North American Land-Mam- ec ectopterygoid mal "Ages." Am. Mus. Novitates 2840: EF exochoanal fenestra 68 pp. eo exoccipital McDowell, S. B., and C. M. Bogert f frontal 1954. The systematic position ofLanthanotus IOF interorbital foramen and the affinities of anguinomorphan J jugal lizards. Bull. Am. Mus. Nat. Hist. 105: lacrimal 1-141. m maxilla Mertens, R. MPA maxillo-premaxillary aperture 1942. Die Familie der Warane (Varanidae). n nasal Dritter Teil: Taxonomie. Abh. Senck- p parietal enb. Naturforsch. Ges. 466: 235-391. p1 palatine Oelrich, T. M. PLF posterior lacrimal foramen 1956. The anatomy ofthe head of Ctenosaura 1992 NORELL ET AL.: ESTESIA MONGOLIENSIS 23

APPENDIX 1-(Continued) APPENDIX 2-(Continued) pm premaxilla 20. Quadrate with large outer conch (0), or conch re- po postorbital + postfrontal duced (1). pr prootic 21. Muzzle tapered, narrowing anteriorly (0), or blunt prf prefrontal and rounded (1). 22. Posterior lacrimal foramen single (0), or double (1). pt pterygoid 23. Premaxillary teeth large (0), or abruptly smaller than q quadrate maxillary teeth (1). SF suborbital fenestra 24. Plicidentine teeth absent (0), or present (1). sm septomaxilla 25. Teeth bluntly pointed (0), or sharply pointed, tren- st supratemporal chent, recurved, and widely spaced (1). sq squamosal 26. Successional replacement teeth in resorption pits (0), v vomer or replacement teeth develop posteriorly, no re- VPLF ventral posterior lacrimal foramen sorption pits present (1). vpm ventral process of maxilla 27. Maxillary tooth row extends posteriad of orbit (0), or is entirely antorbital (1). 28. Maxillary teeth number 13 or more (0), or less than 13 (1). 29. Maxillary teeth greater than 9 (0), or less than/equal 9 (1). APPENDIX 2 30. Venom groove absent (0), or present (1). Character Summary of the Varanoidea, Scored on 31. Vomer short (0), or nearly twice the length of pal- Estesia mongoliensis in Table 1. From Pregill et atine (1). al., 1986 32. Palatal shelves of vomer wide (0), or narrow (1). 33. Palatine longer than wide (0), or equally wide as long (1). Skull characters 34. Palatine teeth present (0), or absent (1). 1. Nasal bones paired (0), or fused (1). 35. Pterygoid teeth present (0), or absent (1). 2. Nasal and prefrontal bones in broad contact (0), or 36. Ectopterygoid does not contact palatine anteriorly with little or no contact (1). (0), or does to exclude maxilla from suborbital fe- 3. Nasal and maxillary bones in broad contact (0), or nestra (1). with little or no contact (1). 37. Dentary and surangular overlap considerably (0), or 4. Nasals and maxillary bones in narrow contact (0), very little (1). or not in contact (1). 38. Coronoid and surangular processes of dentary well 5. Nasal process of maxilla rises from the middle (0), developed (0), or processes reduced (1). or posterior (1) aspect of maxillary. 39. Surangular tapered anteriorly (0), or blunt and ex- 6. Frontal more or less parallel-sided (0), or trapezoidal panded anterodorsally (1). (1). 40. Surangular extends well beyond coronoid eminence 7. Subolfactory processes offrontals short, not in con- (0), or does not (1). tact ventromedially (0), or well developed and close- 41. Intramandibular septum (IMS) without posteroven- ly opposed or contacting ventromedially (1). tral notch (0), or notched (1). 8. Subolfactory processes offrontals do not descend to 42. Splenial extends posterior ofcoronoid eminence (0), contact each other anteromedially (0), or do so (1). or does not (1). 9. Subolfactory processes of frontal do not descend to 43. Splenial-dentary suture firm (0), or loose, with much approach or contact each other posteromedially (0), connective tissue between the two bones (1). or do so (1). 44. Splenial does not move with dentary (0), or does 10. Prefrontal does not (0), or does closely approach or (1). contact postfrontal above orbit (1). 45. Coronoid without long anterolateral and antero- 11. Parietal foramen present (0), or absent (1). medial processes (0), or processes present (1). 12. Postorbital present (0), or absent (1). 46. Head scales large and plate-like (0), or partly or 13. Squamosal large, extending to postorbital (0), or small completely fragmented (1). and reduced (1). 47. Osteoderms thin, plate-like (0), or rounded and thick 14. Temporal musculature inserts ventrally (0), or dor- (1). sally (1) on parietal table. 48. Osteoderms fused to skull (0), or not (1). 15. Supraoccipital not in broad contact with parietal (0), or with broad contact (1). 16. Hypoglossal foramen not enlarged (0), or enlarged Axial characters (confluent with vagal foramen) (1). 49. Number of cervical vertebrae eight (0), or nine (1). 17. Carotid duct present (0), or absent (1). 50. Vertebral centra long and neural spines broad (0), 18. Supratemporal process of parietal broad in dorsal or centra short and neural spines narrow and tall aspect (0), or narrow (1). (1). 19. Supratemporal bone does not reach level of apex of 51. Number ofpresacral vertebrae fewer than 30 (0), or parietal notch (0), or does (1). more (1). 24 AMERICAN MUSEUM NOVITATES NO. 3045

APPENDIX 2-(Continued) APPENDIX 2-(Continued) 52. Caudal vertebrae autotomic (0), or not (1). is at least partly deep to M. genioglossus medialis 53. Peduncles on cervical and caudal vertebrae short (1). (0), or long (1). 66. M. genioglossus lateralis single (0), or subdivided 54. Caudal chevrons and cervical hypapophyses (= in- into separate bundles (1). tercenta) contact centrum condyle (0), or on centrum 67. Insertion of M. levator pterygoidii extends poste- only (1). riorly beyond columellar fossa of pterygoid (0), or does not (1). Appendicular characters 68. Anterior head of M. pseudotemporalis profundus 55. Epicoracoid contacts suprascapula and mesoscapula not enlarged (0), or enlarged (1). (0), or not (1). 69. Bodenaponeurosis with broad base (0), or narrow 56. Anterior coracoid emargination present (0), or ab- base attached only to caudomesial edge ofcoronoid sent (1). (1). 57. Posterior coracoid emargination absent (0), or present (1). Other characters 58. Clavicle loop-shaped medially (0), or gracile and not expanded (1). 70. Hemipenis without paired horns as extensions of 59. Interclavicle with long anterior process (0), or pro- main retractor muscles (0), or with them (1). cess short or absent (1). 71. Foretongue not deeply cleft (0), or deeply cleft (not 60. Mesosternum present (0), or absent (1). less than 20% of length) (1). 61. Rib attachments on sternum more than three pairs 72. Foretongue cleft for 20% of length or less (0), or not or three or fewer pairs (1). less than 40% of length (1). (0), 73. Gland of Gabe absent (0), or present (1). Myological characters 74. Calyciform duodenal cells simple (0), or sero-mu- 62. M. episterno-cleido-mastoideus does not reach pa- cous type (1). rietal (0), or has extensive insertion on parietal (1). 75. Cochlear duct not robust (0), or robust and broad, 63. M. constrictor colli does not cover 1st ceratobran- limbus elongate and heavy (1). chials (0), or does (1). 76. Ulnar nerve superficial (0), or deep (1) in forearm. 64. Origin of MAME profundus from supratemporal 77. Second epibranchial present (0), or absent (1). and parietal (0), or supratemporal only (1). 78. Ossified palpebrals present (0), or absent (1). 65. Insertion of M. geniomyoideus is completely su- 79. Scleral ossicles 14 (0), or fewer (1). perficial to M. genioglossus medialis (0), or insertion 80. Lacrimal duct single (0), or double (1).

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