EARLY AND MIDDLE JURASSIC MARINE GASTROPODS FROM THE NEUQUÉN BASIN, ARGENTINA

Systematic knowledge of Early and Middle Jurassic marine gastropods from Argentina has been supplied during the last decade through several contributions. The present paper describes a new marine gastropod fauna for the Jurassic of the Neuquén Basin, represented by four major taxa such as Patellogastropoda, Vetigastropoda, Caenogastropoda and Heterobranchia, including 14 new species of the genera Scurriopsis (Hennocquia), Eucyclus, Pleurotomaria, Laevitomaria, Obornella, Crossostoma, Palaeorissoina, Euconactaeon, Striactaeonina and Sulcoactaeon; members of Ambercyclus and Rhabdocolpus are also described from the studied area. Most of these taxa are first reported in the Jurassic of Argentina, extending their palaeobiogeographical distribution in South America at that time. Particularly, the genera Obornella, Palaeorissoina, and Euconactaeon also extend their chronostratigraphic distribution in the Jurassic marine deposits of the Neuquén Basin, from the late Hettangian (Palaeorissoina) and late Pliensbachian (Obornella) to the Aalenian–Bajocian (Euconactaeon). The new fossils described here expand the known diversity of the marine gastropod faunas in the Jurassic of Argentina and contribute to the paleontological knowledge of the group in the Mesozoic of the Southern Hemisphere.