An updated biosystematic approach to the leiosaurid genus <i>Pristidactylus</i>

Abstract

A general discussion of the intra- and intergeneric biological relationships of the leiosaurid genus <i>Pristidactylus</i> has been carried out. Its cis-trans cordilleran species groups are reported and compared, also in agreement with results of the very recent molecular and morphological research by Frost <i>et al.</i> (2001). The new family Leiosauridae, including <i>Enyalius, Diplolaemus, Leiosaurus</i> and <i>Pristidactylus</i>, is taken into account, and ancient evolutionary relationships of the last named genus are considered. Present specific characters of Chilean, but mainly of Argentinian <i>Pristidactylus</i> taxa, are analyzed and compared. They are likely adaptive features from ancestral times of their common preglacial origin. Critical comments on the now postulated primitive position of the terrestrial forms instead of the formerly accepted arboreal forms as plesiomorphic evolutionary stage are presented as well.