A new trirachodontid cynodont from the lower levels of the Burgersdorp Formation (Lower Triassic) of the Beaufort Group, South Africa and the cladistic relationships of Gondwanan gomphodonts

Authors: ABDALA, F.; NEVELING, J.¹; WELMAN, J.²

Source: Zoological Journal of the Linnean Society, Volume 147, Number 3, July 2006 , pp. 383-413(31)

Publisher: Wiley-Blackwell

Abstract:

We describe a new trirachodontid cynodont from the base of the Burgersdorp Formation (Subzone A fauna of the Cynognathus Assemblage Zone), of the South African Karoo Basin. Langbergia modisei gen. et sp. nov. is characterized by circular to ovoid in outline upper postcanines and the absence of a maxillary platform lateral to the postcanine series. Apart from the new taxon, we recognize two other species of this family in the Cynognathus Assemblage Zone: Trirachodon berryi and Cricodon metabolus, the latter also represented in the Tanzanian Manda Formation. A phylogenetic analysis of gomphodont cynodonts was conducted using a data matrix of 43 craniodental characters and 18 terminals. Trirachodontidae appears as a monophyletic assemblage, with Langbergia appearing as the sister taxon of Cricodon. The monophyly of trirachodontids is weakly supported, however, with one extra step breaking it. Traversodontid cynodont relationships were also inspected and compared with a recent phylogeny proposed for this group. Considering the resulting phylogeny and the sudden appearance and diversification of Cynognathia representatives, the origin of basal Cynognathia (i.e. Cynognathus, Diademodon, and trirachodontids) is suggested to predate their first appearance in the fossil record. © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society, 2006, 147, 383-413.

Keywords: Early/Middle Triassic; Gondwana; phylogeny; Trirachodontidae

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1096-3642.2006.00224.x

Affiliations: 1: Council for Geosciences, Private Bag X112, Pretoria 0001, South Africa 2: Department of Zoology, Free State University, PO Box 339, Bloemfontein, South Africa

Publication date: 2006-07-01

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