Cranial anatomy and phylogenetic position of Suminia getmanovi, a basal anomodont (Amniota: Therapsida) from the Late Permian of Eastern Europe

Abstract

Suminia getmanovi, a recently discovered basal anomodont from the Late Permian of Russia, is characterized by robust, «leaf-shaped» teeth, and a masticatory architecture that is similar to that of the highly diverse and cosmopolitan group of Permo-Triassic herbivores, Dicynodontia (Anomodontia). Based on new material, the skull is reconstructed in three dimensions and described in detail. A cladistic analysis of the basal anomodonts, Patranomodon,Galeops , Otsheria, Ulemica, and Suminia, using 37 cranial characters, resulted in a single most parsimonious tree, in which Suminia is united with the Russian taxa, Ulemica and Otsheria. This clade, diagnosed by four unambiguous characters, is designated as Venyukovioidea. The South African anomodont, Galeops, appears as the sister taxon to Dicynodontia. Patranomodon is the most basal anomodont. The cladistic analysis suggests that a «dicynodont-type» masticatory architecture, with an expanded adductor musculature and sliding jaw articulation, may have originated prior to the advent of the (Venyukovioidea+(Galeops+Dicynodontia)) clade.