Revision of the Tanzanian dicynodont Dicynodon huenei (Therapsida: Anomodontia) from the Permian Usili Formation

PeerJ. 2019 Aug 22:7:e7420. doi: 10.7717/peerj.7420. eCollection 2019.

Abstract

A single species of the dicynodontoid dicynodont Dicynodon is currently recognized from the late Permian Usili Formation of Tanzania: Dicynodon huenei Haughton, 1932. Restudy of the known Tanzanian materials of D. huenei demonstrates that they represent two distinct morphotypes, here considered separate taxa. The holotype of D. huenei is not referable to Dicynodon and instead is transferred to the genus Daptocephalus (but retained as a valid species, Daptocephalus huenei comb. nov.). A number of published dicynodontoid specimens from the Usili Formation, however, are referable to Dicynodon, and are here recognized as a new species (Dicynodon angielczyki sp. nov.) Dicynodon angielczyki can be distinguished from its South African congener Dicynodon lacerticeps by the presence of an expansion of the squamosal and jugal beneath the postorbital bar and a curved, posterolateral expansion of the squamosal behind the temporal fenestra. Inclusion of Dicynodon angielczyki and D. huenei in a phylogenetic analysis supports their referral to Dicynodon and Daptocephalus (respectively). These results indicate higher basinal endemism in large late Permian dicynodonts than previously thought, a sharp contrast to the cosmopolitanism in the group in the earliest Triassic.

Keywords: Africa; Biogeography; Dicynodontia; Permian; Synapsida; Tanzania.

Grants and funding

This work was supported by a grant from the Deutsche Forschungsgemeinschaft (KA 4133-1/1) and from the SYNTHESYS Project (http://www.synthesys.info/), which is financed by European Community Research Infrastructure Action under the FP7 Integrating Activities Programme. There was no additional external funding received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.