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University of California Publications in Zoology 



B 



FIG. 10. Posterodorsal views of the anterior orbital regions of (A) Brachylophus fasciatus (RE 1888) 

 and (B) Conolophus pallidas (MCZ 19111), showing differences in the contacts of the bones in this region. 

 In A the lacrimal (la) contacts the palatine (pal); in B the prefrontal (prf) contacts the jugal (ju). Scale 

 equals 0.5 cm. 



different contacts may be established: between lacrimal and palatine (Fig. lOA), or 

 between prefrontal and jugal (Fig. lOB). Occasionally all four bones meet at a single point. 

 Because the lacrimal-palatine contact occurs in all outgroups except crotaphytines, this 

 condition appears to be plesiomorphic for iguanines. The apomorphic prefrontal-jugal 

 contact is the common condition in Amblyrhynchus and Conolophus. The plesiomorphic 

 condition is characteristic of most species of all other iguanine genera, although Ctenosaura 

 clarki, Cyclura carinata, C. cornuta, and C. ricordii appear to be characterized by the 

 apomorphic condition. This character is also variable within some iguanine species and 

 occasionally even varies between right and left sides of a specimen thus decreasing its value 

 as a systematic character. 



Frontal (Figs. 5A, 6A, 11, 12). The frontal of postembryonic iguanines is an unpaired 

 median bone that forms the dorsal borders of the orbits. It is sutured anteriorly with the 

 nasals and anterolaterally with the prefrontals. Posteriorly the frontal meets the parietal, 

 forming a transverse suture, and posterolaterally it contacts the postfrontal and variably the 

 postorbital bones. The proportions of the frontal vary within Iguaninae. Generally, the 

 frontal is about as wide (at the frontoparietal suture) as it is long (maximum exposed length 

 dorsally), or is longer than wide. Four iguanines have frontals that are markedly wider 

 than long: Amblyrhynchus (Fig. 11) has the relatively widest frontal of all iguanines, 



