96 University of California Publications in Zoology 



Dipsosaurus. Some Enyalioides possess one or two seemingly nonhomologous large, 

 pointed scales dorsal to the tympanum. Some sceloporines have anterior auriculars fully as 

 large in proportion to their body size as those of Sauromalus; I consider this to be 

 convergent. 



Gular Region. All iguanines possess a transverse gular fold, although it is relatively 

 weakly developed in Amblyrhynchus compared to other iguanines. A midsagittal gular 

 expansion, or dewlap, is variably developed, but in no iguanine is it as highly extensible as 

 in Anolis. A large dewlap is present in male Brachylophus fasciatus (Boulenger, 1885; 

 Gibbons, 1981) and in both sexes of B. vitiensis (Gibbons, 1981), Ctenosaura palearis 

 (Bailey, 1928), and Iguana. It is absent in Amblyrhynchus, Conolophus, most 

 Ctenosaura, Dipsosaurus, and Sauromalus, but is weakly developed in Cyclura 

 (Boulenger, 1885) and Ctenosaura bakeri (Bailey, 1928). The presence of a dewlap is not 

 a simple dichotomy, as evidenced by the intermediate condition in Cyclura and Ctenosaura 

 bakeri; nevertheless, a morphological gap exists between those taxa possessing a large 

 dewlap and those in which it is weakly developed or absent. 



A prominent gular fold occurs in all outgroup taxa used in this study and is, therefore, 

 inferred to be plesiomorphic for iguanines. Although the absence of a dewlap is the most 

 common condition among the outgroups, sufficient variation exists that this condition 

 cannot be inferred to be plesiomorphic for iguanines as long as higher-level relationships 

 remain unresolved. The dewlap is absent in Basiliscus, Laemanctus, crotaphytines, 

 Hoplocercus, Morunasaurus, and oplurines, but it is present in Corytophanes and male 

 Enyalioides (Boulenger, 1885). 



Although a dewlap is developed to varying degrees in different iguanines, only the two 

 species of Iguana possess a gular crest, a midsagittal row of enlarged scales extending 

 below the throat along the edge of the dewlap. Because a gular crest is lacking in all 

 outgroup taxa examined except Corytophanes, its presence in Iguana is inferred to be 

 apomorphic. 



Middorsal Scale Row. A row of scales aligned along the dorsal midline is present in all 

 iguanines except Sauromalus. When present, the scales of the middorsal row are 

 differentiated from the neighboring scales, although the degree of differentiation is highly 

 variable. This variation ranges from the small, rounded knobs that form the row in 

 Dipsosaurus to the tall curved spikes of large Amblyrhynchus and Iguana. In some 

 Cyclura (Schwartz and Carey, 1977) and Ctenosaura (Bailey, 1928), the crest formed by 

 the series of modified middorsal scales is interrupted in the shoulder or the sacral region. 

 The presence of a middorsal scale row in the outgroups is highly variable, making it 

 impossible to determine polarity at this level of analysis. A middorsal scale row is present 

 in most basiliscines, Enyalioides, Morunasaurus annularis, and Chalarodon; it is absent in 

 crotaphytines, Laemanctus serratus, Morunasaurus groi, Hoplocercus, and Oplurus. 



Subdigital Scales of the Pes (Fig. 45). The conspicuous combs on the toes of Cyclura 

 have long been used to diagnose this genus and especially to separate it from Ctenosaura 

 (Barbour and Noble, 1916; Bailey, 1928; Schwartz and Carey, 1977). Similar toe 

 denticulations, however, are known to occur in other iguanines (Gibbons, 1981). These 



