The Patagonian Fossil Lizards

Abstract

The squamates constitute a significant part of the present-day South American herpetofauna, being their fossils a crucial evidence for understanding the origin and evolution of the main clades. The fossil record of squamates in Patagonia is still scarce but it represents one of the most prolific of entire South America. An updated systematic review of the available information of Patagonian fossil lizards is summarized in this chapter. The oldest lizards of Patagonia are found as back as the Upper Cretaceous and include materials referred to two of the most diverse extant clades: Iguania and Scincomorpha. Palaeocene and Eocene interestingly do not provide any lizard specimen from this region. The record reappeared in the Late Oligocene with iguanians. A significant increasing of materials is revealed later in the Neogene. Early Miocene lizards include the first appearance of extant species (the iguanids Liolaemus and Pristidactylus, and the teiids Tupinambis and Callopistes). Late Early Miocene deposits provide materials of Pristidactylus and Tupinambis, whereas an indeterminate tupinambine of the Mid-Miocene is the youngest Neogene record of a lizard in Patagonia. Palaeoclimatic changes affected the distributional patterns of lizards in Patagonia, restricting the distribution of Pristidactylus and Tupinambis which, during the Miocene, reached localities southern than at present. The uplift of the austral Andean cordillera would have been decisive for the diversification of Liolaemus and Pristidactylus at both sides the Andes, whereas the trans-Andean teiid Callopistes had a widespread distribution in the past, reaching the Pampean Region and Patagonia, in Argentina.