The southernmost fossil record of Squamates

Abstract

Squamates form a substantial part of the present-day South American herpetofauna, and their fossils constitute an indispensable evidence for understanding the origin and evolution of the main taxa. Squamates are relatively common in Miocene localities of Patagonia, especially in levels of the late early Miocene Santa Cruz Formation. In this contribution, remains of the three species of the extinct iguanid Erichosaurus Ameghino 1899 (E. diminutus, E. bombimaxilla and E. debilis) are redescribed, and new squamate specimens are reported for first time. The genus Erichosaurus is considered invalid. Erichosaurus debilis, E. diminutus and a new specimen are recognized as indeterminate species of the extant polichrotine Pristidactylus, whereas E. bombimaxilla remains as an indeterminate iguanid. Snakes are represented by an indeterminate colubrid. All these specimens, together with a tupinambine teiid previously described for the same formation, represent the southernmost fossil record of squamates in South America and indicate the occurrence of the iguanid Pristidactylus, the teiid Tupinambis and the colubrid snakes south to their present distribution as back as during the early Miocene.