A new early Danian gastropod assemblage contained in the Roca Formation of Río 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, PriscoficusConrad, 1866, CavoscalaWhitfield, 1892,, MicrofulgurFinlay and Marwick, 1937, and CidarinaDall, 1909, for the Danian of Southern South America; the new record of AustrophaeraFurque and Camacho, 1949, FusinusRafinesque, 1815 and HeterotermaGabb, 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.

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