On the postcanine dentition of Pascualgnathus polansku Bonaparte (Cynodontia, Traversodontidae) from the Middle Triassic of Argentina

The dental morphology of Pascualgnathus polanskii Bonaparte (Therapsidi Eucynodonti Tratversodontidie) from the Middle Triassic Rio Seco de la Quebridi Formation (Puesto Viejo Group Argentina) is described and comp tied with that of other basal traversodontid cynodonts Albeit Pascialgnathus is frequently used in phylogenetic analyses neither a del tiled description nor drawings of its postcanines have been published so tar The upper poste mines of Pascualgnathus ire transversely wide rectangular in occlusal view with a lingual cusp connected to the transverse ridge which is located in the center of the crown and one main labial cusp followed by one posterior labial both forming the labial margin The lower poste mines mostly worn out in the known specimens are quadringular until pc6 and then they we rectangular with the major axis anteroposteriorly oriented They have it ill mesial border possibly constituted by one labial and one linguial cusp and a transverse ridge After comparisons the number of cusps in the sectorial labial border of the upper gomphodont teeth frequently used in phylogenetic analyses would not necessary implies real homologies For example poste mine morphologies with one or more cusps anterior to the main labial cusp would not be homologous to morphologies with one or main cusps posterior to the main labial cusp while resulting in similar count of labial cusps (C) 2010 Elsevier Masson SAS All lights reserved