CROMPTODON MAMIFEROIDES GEN. ET SP. NOV., GALESAURIDAE DE LA FORMACION RIO MENDOZA, MENDOZA, ARGENTINA. (THERAPSIDA - CYNODONTIA)

Abstract

Both dentaries with several well preserved postcanines of a new Galesaurid from the Rio Mendoza Formation are described and figured. The postcanine morphology and distribution of the cups is very similar to Thrinaxodon liorhinus but the cingulum is lingually wider. The tooth replacement is of the alternate type, and the characters of the groove for the dental lamina suggest a condition more advanced than in Thrinaxodon. The dentary shows the coronoid, prearticular and angular processes more developed than in Thrinaxodon, and more similar to Tribolodon [rerensis from the Cynognathus Zone. The Therapsids found in association with this new Galesaurid, and the comparisons with the Argentinian Puesto Viejo and Los Chañares assamblages, and with the Cynognathus Zone suggest, on the basis of the available data, an uppermost Lower Triassic age for the Rio Mendoza tetrapods, which means the same age than the Puesto Viejo, but earlier than Los Chañares assamblages.