Rescued from the collections: the presence of the African cynodont Aleodon (Cynodontia, Probainognathia) in the Triassic of southern Brazil, hidden for over 30 years

AGUSTIN MARTINELLI; KAMMERER, CHRISTIAN F.; MELO, TOMAZ P.; PAES NETO, VOLTAIRE D.; ANA MARIA RIBEIRO; ATILA DA ROSA; CESAR SCHULTZ; MARINA BENTO SOARES

Jornada; Paleo RS 2016; 2016

Aleodon is a basal probainognathian cynodont with an unusual postcanine dentition, including transversely-expanded postcanines similar to those of gomphodont cynognathians. This genus was first discovered in the Manda Formation of Tanzania and subsequently reported from the upper Omingonde Formation of Namibia. In this contribution we report the first occurrence of this enigmatic African cynodont in the Middle?early Late Triassic of several localities from Rio Grande do Sul, southern Brazil. The record from Brazil is based upon multiple specimens of different ontogenetic stages, including three that were previously referred to the sectorial-toothed probainognathian Chiniquodon theotonicus and two classified as Traversodontidae indet. The first Aleodon specimen from Brazil was recognized on the basis of a tooth-bearing maxilla displayed at the Museu Padre Daniel Cargnin in Mata. Additional specimens of Aleodon were recognized following a careful search of paleontological collections from the Dinodontosaurus Assemblage Zone and further preparation of known cynodont specimens. The discovery of Aleodon in Brazil strengths biostratigraphic correlation with African deposits in Tanzania and Namibia. Faunal overlap with the Namibian record is especially extensive, and includes the cynodonts Luangwa, Chiniquodon, and the dicynodont Stahleckeria potens in addition to Aleodon. Moreover, the re-identification of several previously-described Brazilian ?Chiniquodon? specimens as Aleodon raises new questions about the taxonomy of basal probainognathians and bears on biostratigraphic problems among Middle to Late Triassic basins across Pangaea.