A Comparative Study of Cranial Osteology in the North American Sand Lizards, Genus Uma (Reptilia: Iguanidae)

Abstract

An analysis of cranial osteology and dentition in the five species of Uma currently recognized revealed that they differ in 17 of 21 characters investigated. Phenograms constructed from osteological and dentitional data support the recognition of only three of the five nominal species: Uma notata, U. exsul and U. paraphygas. The three species separate into two groups: U. notata in the north, and a southern group consisting of U. exsul and U. paraphygas. Of the two southern species, U. exsul shares more characters with U. notata than does U. paraphygas. The northern and southern groups differ in dentitional patterns and in the bones involved in the formation of the palate. These differences may be due to U. notata having become adapted to eating mostly moderately active, heavily armored prey, and the southern species having become adapted to eating more highly active, moderately armored prey.