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1996 McGUIRE-SYSTEMATICS OF CROTAPHYTID LIZARDS 19 within Crotaphytus including C. collaris (foramen present in seven of 51), C. grisrneri (three of five), and C. reticulatus (22 of 26). The outgroup taxa are also extremely variable with respect to this feature, preventing its polarization. Phylogenetically useful variation was also observed in the palatine foramina of Phymaturus. In all specimens of Phymatunu examined, the foramina were much larger proportion- ally than those of any other iguanian taxon examined. Pterygoids (Characters 1 8-20; Fig. 2-4, 8, 1 1). - The transverse process of the pterygoid of Crota- phytus bears a sharp vertical crest near its lateral end. This crest is very weak or absent in Garnbelia. A strong vertical crest is present in many iguanian species and its absence may be a synapomorphy for Gambelia. However, this crest appears to be asso- ciated with a more easily definable character of the ectopterygoid and its description is given in the dis- cussion of that element. The transverse processes of Crotaphytus reticulatus and C. dickersonae are more ventrally ex- panded in comparison to the other crotaphytids. This condition is especially extreme in adult male C. dickersonae, which bear a well-developed crest that extends along the ventral edge of the entire transverse process terminating at, or near, the in- terpterygoid vacuity. This crest descends ventrally to a degree seen in no other crotaphytid species. Although it is difficult to compare this feature across a broad range of taxa with very different pterygoid morphologies, a strongly developed crest appears to be present in many corytophanids, chamaeleonids. and polychrotids, as well as within large iguanids. Therefore, this character was left unpolarized. In Garnbelia, the quadrate processes are approximately one-third shorter as a percentage of skull length than they are in Crotaphytus. In Crotaphytus, the posterior part of the skull is clearly longer than that of Gambelia and this is best illustrated by com- paring the posterior extents of the quadrate processes of the pterygoids, the supratemporal processes, and the paraoccipital processes with the posterior extent of the occipital condyle. In adult Cro- taphytus, all three processes project well posterior to the occipital condyle (Weiner and Smith, 1965; Fig. 2, 1 I), while in Garnbelia, they reach a point roughly equidistant with the condyle (Fig. 3,4). This condition is subject to considerable ontogenetic variation, with juveniles of both genera having the three processes extending posteriorly to a point equidistant with the occipital condyle until they reach Fig. 12.-Ventral view of skull of Croraphyrur vestigium (REE 2826, adult male, SVL = 105 mm) showing the extravornerine bones (vertically hatched) present in C. insularis and many C. vesligium. Scale = 5 mm. an SVL of approximately 80-85 mm. At this point in ontogeny, the processes begin to project further posteriorly in Crotaphytus than in Gambelia. The condition observed in adult Crotaphytus appears to be apomorphic and was only observed in large male Basiliscus basiliscus, Pristidactylus (as well as Di- plolaemus and Leiosaurus), Uromastyx acanthinu- rus. U. benti, Lr. rnicrolepis. and Physignathus le- stceurii. This condition may represent an adaptation for more powerful jaw adduction in these lizards. In Crotaphytus and Garnbelia silus, the quadrate processes project posterolaterally at a greater angle (approximately 26-3 1 degrees) than in G. wislizenii and G. copei (approximately 18 degrees). Most of the outgroup taxa appear to be similar to Crota- phytus and G. silus with respect to this feature, although enough variation was observed that the character was leR unpolarized. Ectopterygoids (Character 2 1 ; Fig. 24, I I). -In Crotaphytus, the transverse process of the pterygoid bears a strong vertical crest just medial to its artic- ulation with the ectopterygoid. In Garnbelia, this crest is weakly defined and this appears to be as- sociated with the morphology of the ectopterygoid. The dorsal surface ofthe ectopterygoid is in the form of a sharp transverse edge or ridge that extends to the termination of the medially projecting process.
20 BULLETIN CARNEGIE MUSEUM OF NATURAL HISTORY NO. 32 This ridge bears a posterior projection in Crotaphy- tus that overlaps the strong vertical crest of the transverse process. The ridge does not bear a strong posterior projection in Ga~rzbelia, instead being straight or nearly so. Presence or absence of a posterior projection of this ridge are coded as separate character states. However, there is much variation in the outgroups and this character could not be polarized. The ectopterygoid also bears a strong posterolateral process that is sutured to a similar process of the jugal. Together they form the tubercle that pro- jects posterolaterally just beyond the termination of the maxillary tooth row (see description of jugal above). Parabasisphenoid (Character 22; Fig. 1 1 ).-Pro- jecting anteriorly from the basisphenoid is the long, blade-like parasphenoid process. Although this is a separate osseous element, it is fused with the basisphenoid in postembryonic crotaphytids and, fol- lowing Jollie (1 960:fig. 3), they are here treated as a single element, the parabasisphenoid. The posterior suture of the parabasisphenoid with the basioccipital differs between Gambelia and Cro- taphyrus. In Gambelia, the parabasisphenoid bears long posterolateral processes that extend to the sphenoccipital tubercles. These processes are absent or extend only slightly beyond the transverse plane of the parabasisphenoid-basioccipital suture in most Croraphytus examined (Fig. 1 l), although they may occasionally reach the base of the lateral process of the basioccipital. The posterolateral processes never were observed to reach the sphenoccipital tubercles, although they nearly reached the tubercle in two of 29 C. collaris (LLG 62, REE 2948). The majority of the outgoup taxa have long posterolateral processes of the parabasisphenoid that reach or nearly reach the sphenoccipital tubercles. Exceptions occur within the families Phrynosoma- tidae, Chamaeleonidae, Tropiduridae, and Poly- chrotidae. In Phrynosomatidae, short processes are present in Petrosaurus. Uta, Urosaurtcs graciosus, and Sator grandaerus (but not Sceloportcs, at least those examined here; Appendix l), while in Phg7- nosoma and the sand lizards they are long. There- fore, short processes may be an additional synapomorphy for Petrosaurus plus the Sceloporus group, with a reversal in Sceloporus. Within Chamaeleonidae, short processes are present in Leiolepis belliana, but not Uromastyx or the basal agamines Physignathus lesueurii and Hydro- saurus amboiensis. Within chamaeleonines, Broo- kesia stump$? has short processes, while all of the remaining chamaeleonines examined (Appendix 1) except Chamaeleo kersrenii have long processes. In C. kersrenii, the basioccipital is displaced forward by the exoccipitals such that it does not form the ventral portion of the occipital condyle. As a result, the basioccipital tubercles are found on the exoccipitals rather than the basioccipital. Thus, the ho- mology of the posterolateral processes (or lack there- of) of this species is questionable. In tropidurids, the processes are short in Cten- oblepharys, Liolaemus, and some Lciocephahcs (short in L. barahonensis, L. carinatus, L. lunatus, L. tna- cropus, and L. psammodromus; long in L. green- tvayi, L. melanochlorus, L. personatus, L. schrei- bersi. L. sricrigasrer. and L. vinculum), but long in all of the Stenocercini and Tropidurini examined (Appendix 1) except T. spinulosus and T. tnelano- pleurus, which are nonbasal taxa (Frost, 1992). Within polychrotids, the processes are short in Pristidacrylus, Diplolaemus, Leiosaurus, the anoles, the para-anoles (intraspecifically variable in Uros- trophus vautieri), and some Polychrus acutirostris (but not P. marmorarus), but long in Enyalius. Long posterolateral processes represent the ancestral condition in Hoplocercidae, Opluridae, Cor- ytophanidae, Iguanidae, and Chamaeleonidae, and the polarity of this character is equivocal for Phry- nosomatidae and Tropiduridae (but long processes may be ancestral for Tropiduridae). It is most par- simonious to assume that short posterolateral processes were present in the common ancestor of Po- lychrotidae. Thus, the presence of short posterolateral processes are treated as the derived state within Crotaphytidae. Additional intergeneric variation was also observed in the parabasisphenoid. At the anterodorsal end of the basisphenoid is a depression, the sella turcica, that houses the pituitary gland. In adult Cro- taphytus, the sella turcica usually is elevated such that in lateral view, it is visible above the quadrate process of the pterygoid. In Gambelia, the sella turcica is more depressed and is rarely visible above the quadrate process. However, continuous variation exists in this characteristic and it was omitted from the phylogenetic study. MANDIBLE Denrary (Fig. 13, 14). -In many iguanian lizards, the dentary is tubular anterior to the splenial and
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