Cranial anatomy of the Late Permian dicynodont Diictodon , and its bearing on aspects of the taxonomy, palaeobiology and phylogenetic relationships of the genus.

摘要

A study of the Late Permian dicynodont Diictodon confirms suggestions that only one species, D. feliceps, can be presently recognized. The genus is characterized by features such as a palatal notch, a large dentary table with a medial cutting blade, and the absence of postcanine teeth.; Numerous anatomical variations exist within Diictodon, but many appear biologically insignificant. However, there is a clear distinction between specimens having canine tusks and those lacking them, as tusked specimens are generally larger and more likely to develop a pineal boss. This probably reflects sexual dimorphism, with the tusked sex almost certainly being the male.; A phylogenetic analysis of dicynodonts indicates that previous analyses are correct in identifying Robertia as the sister-group of Diictodon and Dicynodon and Aulacephalodon as close relatives of Lystrosaurus. However, the results suggest that Endothiodon, rather than Eodicynodon , may be the most basal known dicynodont.