The first record of Purussaurus (Crocodylia, Alligatoridae) in the Late Miocene of Argentina

Abstract

: Herein we report the first record of Purussaurus Barbosa-Rodrigues, 1892 for the Neogene of Argentina. This genus is recorded in Miocene beds of different localities in Colombia, Venezuela, Brazil, and Perú, and includes at least three different species with total body lengths ranging from 8 to 13 m. The material reported here is a partially preserved tooth (MAS-PV 386) found at the locality Toma Vieja (Paraná, Entre Ríos Province, Argentina), in strata informally known as “Conglomerado osífero” or “Mesopotamiense” (Late Miocene) and traditionally regarded as the basal levels of the Ituzaingó Formation. The material corresponds to the apical portion of a conical crown, slightly compressed, lingually curved, and with a subrounded apex. The enamel is ornamented with thin apicobasal ridges that are anastomosed and separated by shallow grooves. These ridges are transversely crossed by shallow lines that give the enamel surface a crackled aspect. The crown has a continuous carina formed by the enamel that runs along the mesial and distal surface of the tooth, which divides the vestibular (or labial side of the tooth) and lingual faces of the crown that are subequal in size. The carina is ornamented with fine enamel wrinkles that are parallel to each other and perpendicular to the mesiodistal carina. This condition, known as pseudoziphodonty, together with the enamel structure and overall shape of the crown, allow referring the specimen MAS-PV 386 to Purussaurus sp. This finding represents the southernmost record of one of the largest predatorial neosuchian crocodylians which inhabited the wetlands that developed during the Late Miocene in South America.