The pectinoidean genera Delectopecten Stewart, 1930 and Parvamussium Sacco, 1897 in the Danian of Northern Patagonia, Argentina

Abstract

The pectinoidean genera Delectopecten STEWART, 1930 (Family Pectinidae) and Parvamussium SACCO, 1897 (Family Propeamussiidae) are poorly known from Paleocene rocks. The present study provides the first fossil record of Delectopecten in Argentina, with the description of two new species, Delectopecten neuquenensis n. sp. and Parvamussium bayosense n. sp., from the Danian Jagüel and Roca formations of the Neuquen Basin (Río Negro and La Pampa provinces). Parvamussium and Delectopecten have a cosmopolitan distribution at present, mostly inhabiting abyssal and bathyal depths, with the highest species diversity in the tropical Indo-West Pacific Ocean. As with other benthic invertebrate groups restricted to deep water at present, both genera inhabited shallow environments during the early Cenozoic, and it is no surprise that they occur in Paleocene carbonates in the eastern sector of the Neuquen Basin. According to the known record, the earliest occurrence of Delectopecten is in Paleocene rocks of Australia and Patagonia, but this largely reflects the great scarcity of early Cenozoic fossil localities in the Indo-Pacif ic region.