Phylogenetic Systematics of [guanine Lizards 



141 



FIG. 52. Geographic distribution oi Dipsosaurus (modified from Stebbins, 1966). 



94-A. Caudal scales in adjacent verticils approximately equal in size, smooth or keeled 

 but not spinous. 



95- A. Body laterally compressed or roughly cylindrical. 



Dipsosaurus Hallowell 1 854 



Type species (by monotypy): Crotaphytus dorsalis Baird and Girard 1852. 



Etymology: (Greek) Dipsa, thirst(y), + sauros, lizard. Dipsosaurus was first known 

 from the "Colorado Desert" of western North America, as Hallowell (1854:92) described it 

 "a country without water." 



Definition: The most recent common ancestor of the populations of Recent 

 Dipsosaurus dorsalis and all of its descendants. 



Distribution: Deserts of the southwestern United States in southeastern California, 

 southern Nevada, southwestern Utah, and western Arizona, southward into Mexico 

 through western Sonora and northwestern Sinaloa and into Baja California to its southern 

 end, including various islands in the Gulf of California (Fig. 52). 



