A new large gomphodont from the Triassic of South Africa and its implications for Gondwanan biostratigraphy

ABSTRACT

A partial skull (BP/1/7976) of a very large cynodont from the Middle Triassic Cynognathus Assemblage Zone (Cricodon-Ufudocyclops subzone) of South Africa is described. The specimen represents a new gomphodont taxon, Impidens hancoxi, gen. et sp. nov., diagnosed by five sectorial teeth constituting just over half of the length of the upper postcanine tooth row, and enlarged canine and incisor teeth. BP/1/8123, a skull fragment also from the Cricodon-Ufudocyclops subzone, and AMNH FARB 24421, a partial skull from the upper Fremouw Formation of Antarctica, are also referred to the new species. The presence of this taxon in both the upper Fremouw Formation and Cricodon-Ufudocyclops subzone strengthens evidence of biostratigraphic correlation between these units. Impidens hancoxi, with an inferred skull length of up to 460 mm, was a large-bodied and likely omnivorous gomphodont, and may have played the role of apex predator within the tetrapod fauna of the Cricodon-Ufudocyclops subzone.

ACKNOWLEDGMENTS

We thank D. Osborne, owner of the farm Thala on which BP/1/7976 and BP/1/8123 were found, and Eve and Bernhard Howe for helping us arrange access and providing logistical support. We thank all members of the 2014 and 2017 field teams: E. Bordy, D. Cashmore, M. Day, K. Dollman, E. Dunne, M. Ezcurra, P. Godoy, A. Jones, B. McPhee, J. Neenan, P. Viglietti, and R. Sookias. We thank Pepson Mukanela for his preparation work on the specimen. We thank V. Radermacher for assisting us in improving the quality of the illustrations in this paper. Funding for field work was provided by a Marie Curie Career Integration Grant (630123 to R.J.B.), the NRF African Origins Platform (98800 to J.N.C.), and by the Palaeontological Scientific Trust (J.N.C.). C.H. was supported by a Postdoctoral Fellowship from the University Research Committee (URC) of the University of the Witwatersrand and the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET; Beca Pos-doctoral CONICET Legajo 181417). The support of the DST-NRF Centre of Excellence in Palaeosciences (CoE-Pal) towards this research is hereby acknowledged (for their role in funding F.B.T.). Opinions expressed and conclusions arrived at, are those of the author and are not necessarily to be attributed to the CoE. F.B.T. also received funding from The Palaeontological Scientific Trust (PAST), Johannesburg, South Africa.