Phylogenetic Systematics oflguanine Lizards 83 



most iguanines, the surfaces of the scapulae and suprascapulae form a continuous, laterally 

 convex arc, but in Sauromalus the junction of these surfaces is angular and the 

 suprascapulae are oriented more horizontally than in other iguanines. The condition of the 

 suprascapulae in Sauromalus is presumably related to the depressed body form of these 

 animals, and on the basis of outgroup comparison is almost certainly apomorphic. 



Scapulae, Coracoids, and Epicoracoids (Fig. 40). The scapula and coracoid of each 

 side are closely associated and function as a single unit. Although separated by a suture 

 throughout most of the period of growth, the two bones fuse to form a single 

 scapulacoracoid element near the attainment of maximum size. Prominent features of the 

 scapulocoracoids are the glenoid fossae for the articulation of the humeri, which lie at the 

 junctions between scapulae and coracoids along their posterior edges, coracoid foramina 

 anteroventral to the glenoid fossae, and three or four (rarely two) scapulocoracoid 

 fenestrations on each side of the girdle, the functional significance of which is discussed by 

 Peterson (1973). 



The scapulocoracoid fenestrations pierce the pectoral girdle along the anterior margins 

 of the scapulae and coracoids, between these bones and the cartilagenous epicoracoids 

 (Fig. 40). Following the terminology of Lecuru (1968a), from dorsal to ventral the four 

 pairs of fenestrations are: (1) scapular fenestrae, which lie anterodorsally within the 

 scapulae; (2) scapulocoracoid fenestrae, situated at the junctions between scapulae and 

 coracoids; (3) anterior (primary) coracoid fenestrae, located within the coracoids; and (4) 

 posterior (secondary) coracoid fenestrae, also located within the coracoids but 

 posteroventral to the anterior coracoid fenestrae. All iguanines invariably possess the 

 scapulocoracoid and the anterior coracoid fenestrae; the scapular fenestrae and the posterior 

 coracoid fenestrae may be present or absent. 



Scapular fenestrae are invariably present in all iguanines except Amblyrhynchus and 

 Sauromalus, in which they are small or occasionally absent. Outgroup analysis yields 

 equivocal results concerning the polarity of these character states. Scapular fenestrae are 

 present in crotaphytines, the single Enyalioides oshaughnessyi examined, Chalarodon, and 

 Oplurus cuvieri; they are absent in basiliscines, other morunasaurs, and Oplurus 

 quadrimaculatus (in which the large "scapulocoracoid" fenestrae may be homologous with 

 the scapular plus the scapulocoracoid fenestrae of other oplurines). Because of this 

 ambigiuty, I used the presence or absence of scapular fenestrae as a systematic character 

 only at a level less inclusive than all iguanines. 



The presence of posterior coracoid fenestrae is more variable intragenerically than the 

 presence of scapular fenestrae. Posterior coracoid fenestrae are invariably absent in 

 Brachylophus (Fig. 40A); usually absent in Dipsosaurus; usually present in 

 Amblyrhynchus, Ctenosaura (Fig. 40B), Cyclura, and Sauromalus (Fig. 40C); and 

 invariably present in Conolophus and Iguana. The amount of variability differs among the 

 genera in the third group. Posterior coracoid fenestrae are frequently absent in 

 Amblyrhynchus and Sauromalus, in which all species are variable in the presence of these 

 fenestrae except S. australis and S. slevini, both of which are represented by small samples 

 (n=2). The absence of a posterior coracoid fenestra is rare in Ctenosaura; it has been 



