The Cranial Osteology of Gerrhonotiform Lizards

The osteocranium of the gerrhonotiform lizards is described in detail with the aim of clarifying their generic status and providing osteological information for further comparative studies of the higher taxa of the Anguidae. No consistent osteological differences exist in the skulls of the three groups sometimes identified as Elgaria, Barisia, and Gerrhonotus. Variations are noted, but none are diagnos- tically characteristic of any one particular group. Taxonomic use of the oviparous-viviparous criterion of lizard relationships is discussed; this criterion is, by itself, of doubtful taxonomic importance. The findings of the present study do not permit reevaluation of the generic status of the gerrhonotiform lizards on an osteological basis. It is suggested that the absence of osteocranial distinctions is due to the unusual stability of the osteocranium of the gerrhonotiform lizards.