New Early Jurassic gastropods from west−central Patagonia, Argentina

A new gastropod fauna is reported from Chubut province of west−central Patagonia. Members of Trochoidea, Pseudo− melanoidea, Campaniloidea, and Nerinoidea are recorded from the Early Jurassic (Late Pliensbachian–Early Toarcian) of Mulanguińeu Formation. The gastropod fauna consists of two new species: the pseudomelaniid Pseudomelania feruglioi sp. nov. and the protorculid Anulifera chubutensis sp. nov. Other members of the association are Pseudomelania sp.; the ampulloispirids Globularia cf. catanlilensis, Globularia sp., and Naricopsina? sp.; the nerineids Nerinea? sp. 1 and Nerinea? sp. 2; the trochids Lithotrochus humblodtii, Lithotrochus cf. rothi, and two indeterminable trochids species. An analysis of diversity was made considering all gastropod fauna recovered so far from five fossiliferous localities sam− pled in west−central Patagonia. The preliminary results of this study suggests that the Jurassic marine sequences of west central Chubut province are dominated by gastropods of Eucyclidae, Pseudomelaniidae, Procerithiidae, and Ampul− linidae groups. However, the rarefaction curves of particular marine gastropod faunas in the Jurassic of Patagonia are still far from saturation requiring further collecting effort