64 University of California Publications in Zoology 



basiliscines) and are directed posteroventrally; the tips of these teeth may also curve 

 posteriorly. In most iguanines, the number of pterygoid teeth increases ontogenetically, 

 though this increase is less conspicuous in species with small maximum numbers of 

 pterygoid teeth. 



Pterygoid teeth are present in all four outgroups examined and lie in a single row close 

 to the ventromedial edge of each pterygoid, next to the pyriform recess. The posterior end 

 of the row may be displaced slightly laterally. This plesiomorphic condition is retained in 

 Brachylophus, and is also seen in some Cyclura and Sauromalus as an individual variant. 

 A modification of this condition seems to have occurred by lateral displacement of the 

 posterior end of the tooth row toward the base of the transverse process of the pterygoid, 

 with an accompanying tendency for this posterior portion of the tooth row to double 

 ontogenetically. Beneath the posterior end of the tooth row a bony mound may be raised. 

 An ontogenetic transformation from the presumed plesiomorphic condition mirrors the 

 hypothesized phylogenetic transformation of terminal morphologies based on outgroup 

 comparison. This apomorphic condition is seen in adult Ctenosaura and in some Cyclura 

 and Sauromalus. 



Two independent phylogenetic transformations appear to have been derived from the 

 apomorphic condition described above. The first, seen in Iguana, results ontogenetically 

 and presumably was derived phylogenetically from an increase in the number of pterygoid 

 teeth and a more extensive doubUng of the tooth row late in ontogeny. The second, seen in 

 Amblyrhynchus, apparently resulted from loss of the anterior portion of the tooth row; the 

 remaining teeth are located in a short, laterally displaced patch, even in juveniles. 



Pterygoid teeth are usually absent in Conolophus and Dipsosaurus (occasionally absent 

 in individual specimens of Sauromalus), but their absence in these two taxa appears to 

 represent separate derivations from different antecedent conditions. In the rare specimens 

 oi Dipsosaurus that have pterygoid teeth, these teeth are present in a single row near the 

 medial edge of the bone, suggesting derivation from the plesiomorphic condition. This 

 inference is complicated by the small size of Dipsosaurus combined with the large size at 

 which lateral displacement of the row occurs in taxa that exhibit this derived condition. 

 When pterygoid teeth are present in Conolophus they are located laterally, near the base of 

 the transverse process. This suggests that lateral displacement of the posterior end of the 

 tooth row (an apomorphic condition) preceded tooth loss; the reduction of the anterior end 

 of the tooth row seen in Amblyrhynchus is a likely intermediate state. 



Figure 31 is a hypothetical character phylogeny for the iguanine pterygoid tooth patch. 

 The three most speciose iguanine genera, Ctenosaura, Cyclura, and Sauromalus, exhibit 

 much variation in their pterygoid teeth. They are all considered to exhibit one of the two 

 initial modifications of the plesiomorphic condition in the diagram, although this treatment 

 ignores much of the actual variation. Because of the complexity of this character, it is 

 necessary to subdivide it into three characters so that coding will accurately reflect the 

 hypothesized phylogenetic transformations. 



The number of teeth on a single pterygoid is highly variable among iguanine taxa; 

 however, allometric increase in this feature makes intertaxic comparison difficult among 



