Phylogenetic Systematics oflguanine Lizards 39 



dorsomedially with the supratemporal, and ventromedially with the pterygoid. The 

 quadrate is bowed forward, and its lateral edge, the tympanic crest, supports the anterior 

 edge of the external tympanic membrane. In small species and juveniles of larger species, 

 the quadrates tilt backwards with their articular condyles lying anterior to the transverse 

 plane at the posterior end of the occipital condyle. During ontogeny the articular condyles 

 move posteriorly, eventually coming to lie posterior to the occipital condyle and giving the 

 quadrates a forward tilt. A related change occurs in the pterygoids, which must elongate 

 posteriorly as the articular condyles move backwards if they are to remain connected to the 

 quadrates. Variation in the relationship of the squamosal to the quadrate has been described 

 above. 



PALATE 



The iguanine palate (Fig. 5B) consists of four pairs of dermal bones that form the floor of 

 the skull proper and the roof of the mouth: vomers, palatines, pterygoids, and 

 ectopterygoids. 



Vomers (Fig. 5B). The vomers are the anteriormost bones of the palatal complex. 

 They are paired elements lying on either side of the midline and articulating with the 

 maxillae and premaxilla anteriorly, the septomaxillae dorsally, and the palatines posteriorly. 

 The shape of the vomers differs both among iguanine genera and among iguanines and 

 various outgroups; however, I was unable to partition this variation into character states 

 and to assess its polarity. 



Palatines (Figs. 5B, 16, 17, 18). Just posterior to the vomers lie the paired palatines, 

 which form the major portion of the palate. These bones also make up the anterior floor of 

 the orbits and the posterior floor of the nasal capsules. Each palatine has three processes: 

 the vomerine process anteriorly, the maxillary process laterally, and the pterygoid process 

 posteriorly. 



In Brachylophus, Ctenosaura, Cyclura, Dipsosaurus, Iguana, and Sauromalus, as well 

 as in basiliscines, crotaphytines, oplurines and morunasaurs, the vomerine process of the 

 palatine bears a low ridge that extends longitudinally along its dorsomedial edge (Fig. 

 16A). This ridge bends laterally at the posterior end of the nasal capsule. In place of the 

 low ridge, Amblyrhynchus and Conolophus have a high crest and thus greater bony 

 separation of the nasal capsules (Fig. 16B). 



Behind the maxillary process, the palatine forms the medial border of the suborbital 

 fenestra (inferior orbital foramen of Oelrich, 1956). In this region, the palatines of some 

 Sauromalus differ from those of all other iguanines and all outgroups examined in this 

 study in that their lateral borders are fringed along the anterior margins of the suborbital 

 fenestrae. I have observed this feature in several species of Sauromalus, but its presence 

 always appears to be variable. 



The infraorbital foramen, which transmits the superior alveolar nerve and artery 

 (Oelrich, 1956), pierces the anterior orbital wall in the region of the maxillary process of 

 the palatine. The exact position of the foramen relative to this process varies within 



