FIRST CALLOVIAN PLESIOSAURS FROM THE NEUQUEN BASIN, ARGENTINA

Abstract

The first Callovian Elasmosauridae, Cryptoclididae and Pliosauridae (Reptilia: Plesiosauria) have been discovered in the Eastern South Pacific. Isolated bones of cf. Muraenosaurus, ef. Cryptoclidus and a pliosaurid were found in Chacaico Sur, Neuquén Basin (Argentina). Both, Muraenosaurus Seeley and Cryptoclidus Seeley are common in the Oxford Clay (Callovian) of England. The presence of similar forms in the Eastern South Pacific, that possibly may belong to the same genera, suggests biogeographical links with the European Tethys. The Callovian seas of Chacaico Sur area probably were rich in macroinvertebrates and fishes -and perhaps other reptiles- to support such a variety of predatory marine reptiles. The general environment was a shallow marine platform that constituted part of a deltaic system dominated by basinal processes. In the fossiliferous section, sedimentation occurred in high energy environment, associated with tidal currents and storm events, that favoured the dismembering and accumulation of isolated bones.