The relationship between characters and ecology can provide adaptive responses. These adaptations are the result of selective pressures acting on organisms as well as the type of prey consumed or the environment in which they find themselves. Therefore, organisms that exhibit certain morphology traits that allow them to exploit available resources. Sceloporus is a highly diverse group of lizards in North America besides living in diverse habitats, they make an excellent model for testing adaptive and evolutionary hypotheses. The aim of this study was to assess whether there are morphological differences in the heads of some species of Sceloporus and determine whether the morphology emerges as an adaptive response to the type of prey, or habitat use. Eight morphometric variables of the head of 20 different species of this genus were found and collected throughout Mexico. Data on diet and habitat use were obtained from literature and correlated with morphological analysis of this study. The results indicate a clear difference between species for five of the eight variables measures, including top of the head, nose, jaw, mandibular symphysis and retro articular process was observed. Furthermore, it was found that the width and height of the head, is related to the type of prey lizards consumed, and only the top of the head, is correlated with habitat use. Based on these results, it is proposed that the morphology of the heads of lizards analyzed, is being shaped by the type of prey consumed, and not the environment, such as observed in other lizards.

KEY WORDS: Morphology; Head; Adaptation; Sceloporus; Diet; Habitat use.