Patellogastropoda and Vetigastropoda (Mollusca, Gastropoda) from the marine Jurassic of Patagonia, Argentina

Abstract

Gastropod faunas from the Early Jurassic (Late Pliensbachian–Early Toarcian) marine deposits of Chubut Province, Argentina, are described from Lomas Occidentales, Cerro La Trampa and Puesto Currumil localities, representing eight species, three of them new. These are Scurriopsis? sp., Chartronella gradata sp. nov., Calliotropis? sp., Pleurotomaria sp., Leptomaria sp., Hamusina? wahnishae sp. nov., Colpomphalus musacchioi sp. nov. and Jurassiphorus? cf. triadicus Haas. The gastropod assemblage reported here testifies paleobiogeographical connections with other coeval gastropod associations from the western Tethys. However, Chartronella, Hamusina and Jurassiphorus may represent survivors of Triassic associations, considering the ancient seaway from Peru as the most plausible hypothesis for biotic exchange of these faunas during the Late Triassic–Early Jurassic boundary. An abundant and diverse invertebrate fauna such as corals, echinoderms, cephalopods, brachiopods, bivalves and other gastropods found in association with the gastropods described here characterises a shallow marine environment for the gastropod-bearing rocks.http://www.zoobank.org/urn:lsid:zoobank.org:pub:7B8EAFC0-3AC0-4F91-97A5-22AAC6A19909

Keywords::

• Gastropoda
• paleobiogeography
• paleoecology
• Jurassic
• Patagonia

Acknowledgements

The present research is part of a PhD thesis prepared at the Museo Paleontológico Egidio Feruglio (Trelew, Argentina) supervised by Dr Susana Damborenea (Museo de Ciencias Naturales de La Plata) and Dr Alejandra Pagani (Museo Paleontológico Egidio Feruglio, Trelew). The author is deeply grateful for their guidance and help during the preparation of this work. The author especially thanks Susana Damborenea for drawing the stratigraphical sections of Lomas Occidentales, Cerro La Trampa and Puesto Currumil fossiliferous localities and Pablo Puerta, Mariano Caffa and Leandro Canessa (all at Museo Paleontológico Egidio Feruglio, Trelew, Argentina) for their help during field work and, especially, Leandro Canessa for his laboratory work. The author also thanks Jaime Groizard (ALUAR, Pto. Madryn, Argentina) for allowing the access to the SEM. The author is grateful to Museo Paleontológico Egidio Feruglio and to Dr Rubén Cúneo (Museo Paleontológico Egidio Feruglio director) for financing the fieldworks and supplying the necessary equipment to carry out the present research.