Phylogenetic Systematics oflguanine Lizards 



43 



FIG. 18. Ventral view of the skull oi Iguana delicatissima (MCZ 16157), showing the medial curvature 

 of the pterygoids and concomitant abrupt narrowing of the pyriform recess. Scale equals 1 cm. 

 Abbreviations: pa, palatine; pt, pterygoid; vo, vomer. 



Pterygoids (Figs. 5B,C, 6A, 18). These paired bones are the posteriormost palatal 

 elements. Each pterygoid bears three processes: an anteriorly directed palatine process, an 

 anterolaterally directed transverse process, and a longitudinally compressed and posteriorly 

 directed quadrate process. The ventral surface of the palatine process often bears small 

 teeth. Anterior to the pterygoid notches, where the basipterygoid processes of the 

 basisphenoid articulate with the pterygoids, the medial edges of the pterygoids of most 

 iguanines curve towards the midline, resulting in a sudden narrowing of the pyriform 

 recess (interpterygoid vacuity) (Fig. 18). In contrast, the medial edge of the pterygoids in 

 Brachylophus is relatively straight, and the pyriform recess narrows more gradually from 

 posterior to anterior (Fig. 5B). 



Outgroup comparison suggests that the condition seen in Brachylophus is 

 plesiomorphic. Among the four outgroups, only crotaphytines exhibit the strongly curved 



