Phylogenetic Systematics oflguanine Lizards 35 



comparison has limited value here, because no other iguanids get as large as the largest 

 iguanines; and the basiliscines, moderately large iguanids, have highly modified parietals. 

 Nevertheless, a few observations warrant mention. The lateral parietal crests of 

 Sauromalus never meet, despite the fact that some of its species (5. hispidus and S. varius) 

 attain larger sizes than other iguanines in which the crests do eventually meet (e.g., 

 Brachylophus). In Amblyrhynchus, one of the largest iguanines, the parietal crests do 

 eventually meet, but this occurs at a larger size than in other iguanines, and a Y-shaped roof 

 does not develop. If the complete ontogenetic pathway described above is plesiomorphic 

 for iguanines, then Sauromalus and Amblyrhynchus exhibit derived conditions. Because 

 of the ambiguities involved in this character, however, I omitted it from the phylogenetic 

 analysis. 



A unique feature of the parietal is seen within the genus Ctenosaura. In C. acanthura 

 and C. pectinata, the parietal extends posteriorly, forming a shelf above the braincase (H. 

 M. Smith, 1949, and pers. comm. cited by Ray and Williams, unpublished). This feature 

 suggests that C. acanthura and C. pectinata form a clade within Ctenosaura, and it is used 

 as a systematic character only in an analysis of relationships within that taxon. 



Supratemporals (Figs. 5C, 6A). The supratemporals are small bones that form the 

 major part of the articulation for the dorsal end of the streptostylic quadrates. The posterior 

 end of each supratemporal is wedged between four bones: the quadrate ventrally, the 

 squamosal laterodorsally, the parietal dorsally, and the exoccipital medially. In all 

 iguanines, the posterior end of the supratemporal wraps around the ventral edge of the 

 supratemporal process of the parietal. As it extends anteromedially, the supratemporal 

 becomes confined to the posteromedial surface of the supratemporal process. The greater 

 part of the supratemporal lies on this posteromedial surface. In most other lizards, the 

 supratemporal lies primarily on the anterolateral surface of the supratemporal process of the 

 parietal for its entire length. Sometimes it extends along the ventral edge of the 

 supratemporal process and bears medial and lateral portions of approximately equal size. 

 As far as I am aware, oplurines, Enyalius, and mosasaurs are the only other lizards in 

 which the greater portion of the supratemporal lies on the posteromedial surface of the 

 supratemporal process of the parietal. Therefore, I interpret this condition as an iguanine 

 synapomorphy. 



The anterior extent of the supratemporal varies within Iguaninae. In most, the 

 supratemporal extends forward at least halfway across the posterior temporal fossa. This 

 condition occurs also in basiliscines, crotaphytines, morunasaurs, and oplurines, and is 

 therefore taken to be plesiomorphic for iguanines. The supratemporal of Conolophus has 

 apparently been reduced phylogenetically; it sometimes reaches halfway across the 

 posterior temporal fossa, but generally falls short of this point. 



Maxillae (Figs. 5A,B, 6A, 14). The maxillae are paired bones that bear most of the 

 upper marginal teeth. They are roughly triangular and lie on the anterior sides of the skull, 

 where they meet the premaxilla anteriorly, the nasals and prefrontals dorsally, the lacrimals 

 and jugals posterodorsally, and the ectopterygoid posteriorly. A number of supralabial 

 foramina pierce the maxillae in a row parallel to its ventral border. Compared to the 



