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University of California Publications in Zoology 



B 



FIG. 24. Lateral views of the right mandibles of (A) Conolophus pallidas (RE 1382) and (B) Cyclura 

 cornuta (RE 383), showing differences in the size of the labial process of the coronoid (shaded). Scale 

 equals 1 cm. 



Basiliscines, crotaphytines, morunasaurs, and oplurines have their anterior inferior 

 alveolar foramina either between splenial and dentary or entirely within the splenial. Both 

 conditions are found in all four outgroups. The splenial is relatively larger in most of these 

 outgroups than in any iguanine, which may account for the fact that the foramen of 

 iguanines does not lie entirely within this bone. Because location of the anterior inferior 

 alveolar foramen between splenial and dentary is the only condition that occurs in both 

 ingroup and outgroups, I considered this to be the plesiomorphic condition. The other two 

 positions of the foramen, entirely within the dentary and between coronoid and splenial, 

 were considered to be separate modifications of the plesiomorphic condition. 



Coronoid (Figs. 6B,C, 23, 24). This bone forms a large dorsal process (coronoid 

 eminence) immediately posterior to the tooth row, which serves as the insertion for jaw 

 adductor muscles. It also bears one lateral and two medial ventrally directed processes that 

 straddle the body of the lower jaw. Ahhough absent in many iguanids, the large process of 

 the coronoid that extends over the labial surface of the mandible is present in all iguanines 

 (Fig. 24). This labial extension of the coronoid is most strongly developed in adult 

 Conolophus, in which its ventral border reaches halfway or farther down the mandible and 

 covers the posterolateral end of the dentary (Fig. 24A). In most other iguanines, the labial 

 process of the coronoid is relatively small (Fig. 24B), but in Amblyrhynchus and 

 Brachylophus the size of the process is intermediate between that of Conolophus and those 

 of other iguanines. In both Amblyrhynchus and Conolophus the labial process of the 

 coronoid is relatively small at hatching and increases in size during postembryonic 

 ontogeny. The labial process of the coronoid is very small in basiliscines, crotaphytines, 

 and oplurines. Morunasaurs and other iguanids that possess a large labial process of the 



