Abstract

A new brachyopid temnospondyl is described from the Early to Middle Triassic Cynognathus Assemblage Zone of the upper Beaufort Group, Karoo Basin of South Africa. Vanastega plurimidens, gen. et sp. nov. is the third brachyopid taxon from the South African Karoo and is distinguished from all other brachyopids mainly through a combination of primitive and derived character states. The position of the nostrils exceptionally close to and anteriorly confluent with the skull margin represents the single known autapomorphy of V. plurimidens. Incorporation of V. plurimidens into a data matrix modified from a recent PAUP-based study of brachyopoids produces a phylogeny in which V. plurimidens is the sister species to Vigilius wellesi from the Anisian of North America. In addition, the Brachyopoidea appear to be phylogenetically closer to the Dvinosauria than to other Triassic temnospondyls, with weak support for the alternative hypothesis, which places the Brachyopoidea closer to typical Triassic stereospondyls. This suggests that brachyopids are derived dvinosaurians, in agreement with earlier hypotheses of brachyopoid interrelationships. Stratigraphie calibration of this phylogeny reveals significant ghost lineages primarily within the Brachyopidae and Chigutisauridae, but also suggests a ghost lineage for the Brachyopoidea back into the Late Permian of southern Africa.