Phylogenetic Systematics oflguanine Lizards 63 



large Cyclura. The maximum number of cusps in mature Iguana, however, is greater than 

 in any Cyclura. 



Amblyrhynchus, Ctenosaura bakeri, and C quinquecarinata are the only iguanines that 

 characteristically have a maximum of only three cusps on their marginal teeth. Tricuspid 

 teeth occur throughout the posterior half of the tooth row in juveniles of at least some 

 iguanine species whose teeth later become four-cusped or polycuspate, and they are 

 common outside of iguanines, occurring in basiliscines (Fig. 30D), crotaphytines, 

 oplurines, and most morunasaurs (some Enyalioides are polycuspate). For these reasons, 

 tricuspid posterior marginal teeth are judged to be plesiomorphic for iguanines. The 

 morphology of the tooth crowns in the outgroups, however, differs strikingly from that of 

 Amblyrhynchus, although it is similar to that of the tricuspid teeth found more anteriorly in 

 the tooth row or earlier in the ontogeny of other iguanines. In the tricuspid teeth of all these 

 taxa, the apical cusp is much larger than each lateral cusp. In Amblyrhynchus, the lateral 

 cusps are very large, each being nearly as large as the apical cusp (Fig. 30E). The 

 posterior marginal teeth of Ctenosaura quinquecarinata are similar to those seen in many 

 outgroup taxa. 



Ontogenetic data relating to changes in iguanine tooth crown morphology are few, but 

 what little are available suggest that the adult morphologies of the marginal tooth crowns 

 represent stages in a single transformation series. Tricuspid teeth are judged to be 

 plesiomorphic on the basis of outgroup comparison (see above), and they also occur in the 

 few hatchling specimens examined of those iguanines that, as adults, have four-cusped 

 teeth (Conolophus subcristatus, Ctenosaura hemilopha, C. pectinata, C. similis), 

 polycuspate teeth (Cyclura carinata, C. cornuta, C. nubila), and serrate teeth {Iguana 

 iguana) as adults. Although I have never observed the replacement of four-cusped teeth by 

 polycuspate or serrate teeth, both Sauromalus and Cyclura (which are polycuspate as 

 adults) normally possess four-cusped teeth in some portion of the tooth row. Thus, all 

 iguanine tooth crown morphologies appear to be part of a single transformation series, with 

 tricuspid teeth in the terminal stage at its plesiomorphic pole. I also propose that 

 ontogenetic transformation to polycuspate teeth is a modification of a transformation to 

 four-cusped teeth, and that ontogenetic transformation to serrate teeth is a modification of 

 one to polycuspate teeth. 



Judging from the high numbers of replacement teeth in Amblyrhynchus, these animals 

 probably replace their teeth at higher rates than other iguanines and the members of the four 

 noniguanine outgroups examined in this study. Presumably related to the high numbers of 

 replacement teeth in Amblyrhynchus is a relatively wide alveolar margin on the bones 

 bearing the marginal teeth. 



Palatal Teeth (Fig. 31). Palatal teeth in iguanids may be present on the pterygoids and 

 palatines but never on the vomers. All iguanines lack palatine teeth, which are present 

 (though not invariably) in crotaphytines and oplurines among the outgroups examined. At 

 least some specimens of all iguanine species examined in this study have pterygoid teeth, 

 the number and position of which vary considerably among genera. The pterygoid teeth 

 generally lack lateral cusps (in contrast with the tricuspid pterygoid teeth of some 



