Phylogenetic Systematics oflguanine Lizards 61 



premaxillary teeth. Two specimens of Cyclura pinguis have seven and eight premaxillary 

 teeth. I have assumed that C. pinguis actually has a modal number of premaxillary teeth 

 greater than seven and that the bimodal distribution results from sampling error. It is also 

 possible that a phylogenetic transformation has occurred within Cyclura and that the 

 synapomorphic condition applies to a subset of this taxon, or that the ancestral condition 

 was polymorphic. 



Outgroup comparison yields equivocal results conceming the plesiomorphic number of 

 premaxillary teeth in iguanines. Gambelia has the condition found in most iguanines, a 

 mode of seven premaxillary teeth. Other outgroup s have seven or more premaxillary teeth 

 (basiliscines, Enyalioides); more than seven (Morunasaurus); fewer than seven (oplurines, 

 Hoplocercus); or a range from fewer than seven to more than seven (Crotaphytus, mode of 

 six). Because of this ambiguity, I withheld a decision on the primitive number of 

 premaxillary teeth and used the character only at a level less inclusive than all iguanines. 



In most iguanines the premaxillary teeth, as well as the anterior maxillary and dentary 

 teeth, have fewer or smaller cusps than the posterior maxillary and dentary teeth. In 

 Cyclura and most species of Ctenosaura the premaxillary teeth and the dentary teeth with 

 which they occlude lack lateral cusps. At least some of the premaxillary teeth of some 

 specimens have one or more lateral cusps in Brachylophus, Dipsosaurus, and Ctenosaura 

 palearis, although these lateral cusps are relatively small. Amblyrhynchus and Conolophus 

 almost invariably have two large lateral cusps on their premaxillary teeth. The premaxillary 

 teeth of basiliscines, crotaphytines, morunasaurs, and opliuines usually lack lateral cusps, 

 though small ones may occasionally be present. 



Except in large Ctenosaura, in which the anterior maxillary teeth and the dentary teeth 

 occluding with them are enlarged and recurved to form fangs, these teeth differ only 

 slightly from the marginal teeth anterior to them. Moving posteriorly along the marginal 

 tooth rows, the tooth crowns progressively become more laterally compressed, the size of 

 the lateral cusps increases, and in most iguanines additional lateral cusps are added. Part of 

 the progression is reversed abruptly at the posterior ends of the tooth rows. When strongly 

 compressed, the crowns of the teeth are much wider than their bases and overlap their 

 neighbors in a regular pattern: each tooth is twisted about its long axis so that its anterior 

 edge is lingual to and its posterior edge is labial to the crowns of the adjacent teeth. 

 Maximum cuspation is reached about three-fourths of the way back along the tooth row in 

 adults, and here substantial differences exist among taxa (Fig. 30). The maximum number 

 of cusps on the marginal teeth oi Brachylophus, Conolophus, Dipsosaurus, and most 

 Ctenosaura (C. acanthura, C. clarki, C. hemilopha, C. palearis, C. pectinata, and C. 

 similis) is four: two anterior cusps, an apical cusp, and one posterior cusp (Fig. 30A). 

 This crown morphology is seen in both maxillary and dentary teeth. The size and 

 occurrence of the anteriormost cusp, however, is variable, and it may be absent from all 

 teeth in some specimens of some species. 



Greater cuspation is found in Ctenosaura defensor, Cyclura, and Sauromalus (Fig. 

 BOB). The maximum number of cusps per tooth in these taxa ranges from as few as five in 

 Cyclura pinguis and some C. cychlura up to about 10 in C. cornuta and C. nubila. 



