A new eutherocephalian (Therapsida, Therocephalia) from the upper Permian Madumabisa Mudstone Formation (Luangwa Basin) of Zambia

ABSTRACT

A new therocephalian therapsid, Ichibengops munyamadziensis, gen. et sp. nov., is described on the basis of two partial skulls from the upper Permian (Wuchiapingian) upper Madumabisa Mudstone Formation of the Luangwa Basin, Zambia. The specimens offer insights into the diversity of therocephalians in a poorly sampled region, preserving unique maxillary structures, dental morphology that is intermediate between basal therocephalians and eutherocephalians, and a maxillovomerine bridge forming an incipient secondary palate. A phylogenetic analysis of 135 craniodental and postcranial characters from 56 therapsid taxa (including 49 therocephalians) recovered I. munyamadziensis as the sister taxon of the Russian Chthonosaurus, with both taxa resolving near the hofmeyriid + whaitsiid + baurioid clade (either as the sister group to this clade or nested near whaitsiids). Ichibengops shares with Chthonosaurus several features, including a ventral maxillary flange in which the upper postcanines are situated (also in Lycosuchus), anteroposteriorly short suborbital vacuities with strongly scalloped anterior borders, a furrowed or ridged surface texture on the palatal surface of the palatine, and a possible maxillovomerine bridge (although this latter structure is incompletely preserved in Chthonosaurus). The new taxon, along with its proposed relationship to Chthonosaurus, adds to a list of sister-group pairs of Wuchiapingian tetrapods in southern Gondwana and Laurasia, indicating that effective, though largely unknown, dispersal routes persisted in Pangea at least through early late Permian times.

http://zoobank.org/urn:lsid:zoobank.org:pub:3C00620E-64B4-4CF0-BFAD-0336AE7C8196

SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

ACKNOWLEDGMENTS

We thank the members of the 2009 expedition for companionship in the field, K. Mwamulowe and R. Smith for finding the specimens, L. Herzog for her excellent job of preparation, and J. Lungmus for helping to prepare photographic figures. In addition, we thank A. Carr and A. Frylinck for access to the Munyamadzi area and NHCC for supporting our research. Sidor laboratory members C. Beightol, B. Peecook, and L. Tsuji provided helpful discussions. R. Irmis provided helpful suggestions for the phylogenetic analysis. We thank editor J. Botha-Brink for handling the manuscript, and referees F. Abdala and C. Kammerer for their helpful reviews. Research on the Permian vertebrate fauna of Zambia has been supported by the National Geographic Society (grant 8571-08 to S. Steyer and 8962-11 to C.A.S.), the Grainger Foundation and Field Museum/IDP Foundation, Inc., African Partners Program (to K.D.A.), and the National Science Foundation (EAR-1337569 to C.A.S.; EAR-1337291 to K.D.A.; EAR-1336986 to Peter Roopnarine). A.K.H. has been supported by the National Science Foundation (DEB-12009018 and DEB-1309040).