A NEW EARLY DANIAN GASTROPOD ASSEMBLAGE FROM NORTHERN PATAGONIA, RIO NEGRO PROVINCE, ARGENTINA

A new early Danian gastropod assemblage contained in the Roca Formation of Rio Negro Province was analyzed. Eleven species are described and illustrated, the new genus Rocalaria is created, and six new species are recognized: Gyroscala daniana, Heteroterma carmeloi, Microfulgur concheyroae, Sulcobuccinum prominentum, Cidarina lenzaniyeuensis, and Rocalaria alani. The present research includes the first mention of Sulcobuccinum d'Orbigny, 1850, Priscoficus Conrad, 1866, Cavoscala Whitfield, 1892, Microfulgur Finlay and Marwick, 1937, and Cidarina Dall, 1909, for the Danian of Southern South America; the new record of Austrophaera Furque and Camacho, 1949, Fusinus Rafinesque, 1815 and Heteroterma Gabb, 1869 in northern Patagonia; and the oldest Paleogene record for the genus Gyroscala de Boury, 1887. The presence of the study assemblage in northern Patagonia indicates a more complex paleobiogeographic pattern for the area than previously thought, as shown by the record of endemic genera, cosmopolitan taxa, elements with Tethyan/Indo-Pacific affinities, and genera related with Wangaloan faunas of the Paleocene of New Zealand.