36 University of California Publications in Zoology 



FIG. 14. Lateral view of the skull of Ctenosaura similis (MCZ 21742), showing the dorsal curvature of 

 the premaxillary process of the maxilla (arrow). Scale equals 1 cm. Abbreviations: fr, frontal; ju, jugal; 

 la, lacrimal; mx, maxilla; na, nasal; par, parietal; pmx, premaxilla; prf, prefrontal; ptf, postfrontal; pto, 

 postorbital; q, quadrate. 



supralabial foramina of other iguanines, those of Amblyrhynchus seem to lie slightly higher 

 on the maxillae above a rounded ridge that is not seen in any other iguanine or in any 

 outgroup examined in this study. There is also variation in the relative size of the 

 supralabial foramina within Iguaninae, with large ones being found in some species of 

 Cyclura, especially C. cychlura. This variation is not useful for examining relationships 

 among the basic taxa used in this study, since it occurs in only some Cyclura. 



The maxillae of Ctenosaura are unique in that the premaxillary processes in this genus 

 curve dorsally, so that the premaxilla and the anterior portions of the maxillae are higher 

 than the rest of the upper jaw margin, giving the skull a sneering appearance (Fig. 14). 

 The teeth in this region form large, curved fangs. The dorsal displacement of the anterior 

 end of the tooth row increases allometrically both within and between species of 

 Ctenosaura, being less pronounced in juveniles of large species and in adults and juveniles 

 of small species. In all other iguanines, the entire upper jaw margin lies in a single 

 horizontal plane or is only slightly elevated anteriorly (Fig. 6A). Although no other 

 iguanines nor any of the outgroups exhibit as pronounced a curvature of the premaxillary 

 process of the maxilla as that seen in large Ctenosaura, many taxa are difficult to compare 

 because of their small size and the allometric change seen in this feature. 



Lacrimals (Figs. 5A, 6A, 14). The lacrimals of iguanines are small bones situated at 

 the anterior corner of each orbit. In Amblyrhynchus these bones are relatively small 

 compared to those of other iguanines. Conolophus also has relatively small lacrimals, 

 intermediate in size between those of Amblyrhynchus and the smallest ones seen in other 

 iguanines. All other iguanines have relatively large lacrimals whose size and shape vary 

 among the genera. This variation ranges from the long, curved bones of Brachylophus 



