Galesaurid cynodonts from the Early Triassic of South Africa: another example of conflicting distribution of characters in non-mammalian cynodonts

ABDALA, F.

SOUTH AFRICAN JOURNAL OF SCIENCE

ACAD SCIENCE SOUTH AFRICA A S S AF

Lugar: Johannesburg; Año: 2003 vol. 99 p. 95 - 96

0038-2353

A series of galesaurid non-mammalian cynodont specimens from the Early Triassic Lystrosaurus Assemblage Zone of the Beaufort Group (Karoo Basin) exhibit a mixture of characters present in different non-mammalian cynodont families. The postcanine crownmorphology, lack of a completely closed osseous palate, and well-developed post-dentary bar, are distinctive galesaurid traits. However, all the specimens display an angulation between the ventral edge of the maxillary zygomatic process and the anteroventralmargin of the jugal, a character previously reported as diagnostic for chiniquodontid cynodonts. In addition, three of the specimens exhibit a posteriorly well-projected postero-dorsal portion of the zygomatic process of the squamosal, delimiting a deep squamosal sulcus. This extended posterior projection of the squamosal, although showing different orientations, was previously recognized in cynognathid, gomphodont and tritylodontidcynodonts. This unusual combination of characters in members of the Galesauridae will most likely increase the level of homoplasy in the phylogeny of non-mammalian cynodonts.