The dental morphology of Pascualgnathus polanskii Bonaparte (Therapsida, Eucynodontia, Traversodontidae), from the Middle Triassic Rio Seco de la Quebrada Formation (Puesto Viejo Group, Argentina), is described and compared with that of other basal traversodontid cynodonts. Albeit Pascualgnathus is frequently used in phylogenetic analyses, neither a detailed description nor drawings of its postcanines have been published so far. The upper postcanines of Pascualgnathus are 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 postcanines, mostly worn out in the known specimens, are quadrangular until pc6 and then they are rectangular with the major axis anteroposteriorly oriented. They have a tall mesial border, possibly constituted by one labial and one lingual 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, postcanine morphologies with one or more cusps anterior to the main labial cusp would not be homologous to morphologies with one or more cusps posterior to the main labial cusp, while resulting in a similar count of labial cusps.

中文翻译：

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阿根廷中三叠世 Pascualgnathus polanskii Bonaparte (Cynodontia, Traversodontidae) 的犬齿列

描述了来自中三叠世 Rio Seco de la Quebrada 组（Puesto Viejo Group，阿根廷）的 Pascualgnathus polanskii Bonaparte（Therapsida、Eucynodontia、Traversodontidae）的牙齿形态，并与其他基底 traversodontid cynodonts 的牙齿形态进行了比较。尽管 Pascualgnathus 经常用于系统发育分析，但迄今为止，尚未公布其后犬的详细描述或图纸。Pascualgnathus的上后尖牙横向宽，咬合面呈长方形，舌尖与位于牙冠中央的横脊相连，1个主唇尖，1个后唇尖，形成唇缘。下犬齿，在已知标本中大多磨损，在 pc6 之前是四边形，然后它们是长轴前后方向的矩形。它们有一个高的近中缘，可能由一个唇尖和一个舌尖以及一个横脊构成。经过比较，在系统发育分析中经常使用的上角齿类牙齿的扇形唇缘中的牙尖数量不一定意味着真正的同源性。例如，在主唇尖之前具有一个或多个尖的犬后形态将与在主唇尖之后具有一个或多个尖的形态不同源，同时导致类似的唇尖计数。在系统发育分析中经常使用的上角齿类牙齿的唇缘不一定意味着真正的同源性。例如，在主唇尖之前具有一个或多个尖的犬后形态将与在主唇尖之后具有一个或多个尖的形态不同源，同时导致类似的唇尖计数。在系统发育分析中经常使用的上角齿类牙齿的唇缘不一定意味着真正的同源性。例如，在主唇尖之前具有一个或多个尖的犬后形态将与在主唇尖之后具有一个或多个尖的形态不同源，同时导致类似的唇尖计数。