Phylogenetic Systematics of I guanine Lizards 



31 



mc 



FIG. 12. Ventral views of the frontals of (A) Ctenosaura pectinata (RE 641), (B) Conolophus 

 subcristatus (AMNH 165756), (C) near-hatching Amblyrhynchus cristatus (SDNHM 45157), and (D) adult 

 A. cristatus (RE 1387), showing differences in the morphology of the cristae cranii and the development of 

 crests medial to the cristae cranii. Scale equals 0.5 cm. Abbreviations: cc, crista cranii; fr, frontal; mc, 

 medial crest; prf, prefrontal. 



distinguished from that of all other iguanines and warrants recognition as a character. All 

 outgroups either lack the medial cristae of the frontals or have them only weakly developed. 

 The parietal foramen is a small hole that pierces the dermal skull roof above the anterior 

 portion of the brain. It serves as a window in the skull for the parietal eye, a photosensitive 

 organ (Hamasaki, 1968, 1969). The location of the parietal foramen relative to the frontal 

 and parietal bones is variable within iguanines (Table 2). Because the medial portion of the 



