A redescription of Kunpania scopulusa, a bidentalian dicynodont (Therapsida, Anomodontia) from the ?Guadalupian of northwestern China

ABSTRACT

Permian dicynodonts were discovered in strata exposed on the flanks of the Bogda Mountains (Xinjiang, China) in 1928. Nearly all known specimens were collected in the Guodikeng Formation (= upper Wutonggou low-order cycle); the single exception is the holotype of Kunpania scopulusa, which originated in the underlying Quanzijie Formation. The Quanzijie Formation is generally considered Capitanian in age, which would make Kunpania one of the oldest known bidentalian dicynodonts, but the type of K. scopulusa has received little attention. Here we redescribe K. scopulusa and investigate its phylogenetic relationships. Kunpania scopulusa is a valid species diagnosed by the absence of anterior palatal ridges; a robust crista oesophagea; a prominent lateral dentary shelf; a posteriorly curving projection on the angular; and a large, triangular attachment area for M. latissimus dorsi on the humerus. Our phylogenetic analysis recovered K. scopulusa as a stemward member of Dicynodontoidea and the sister taxon of the South African species Sintocephalus alticeps. Depending on the precise age of the uppermost Quanzijie Formation, three scenarios describe the potential phylogenetic implications of K. scopulusa: (1) bidentalian dicynodonts diversified before the end-Guadalupian extinction, with little of their early history preserved; (2) the main diversifications of cryptodont and dicynodontoid bidentalians occurred in the aftermath of the end-Guadalupian extinction, with K. scopulusa representing the latter; (3) K. scopulusa is a contemporary of other mid–late Wuchiapingian dicynodontoids and the initial radiation of Dicynodontoidea is not preserved in the known fossil record.

ACKNOWLEDGMENTS

We thank H.-L. Fu for undertaking additional preparation of IVPP V 4695. J. Lungmus provided assistance during collections visits. Photos in Fig. 1E–G were taken by C. Kammerer. Funding for this research was provided by NSF EAR-1714829 (to K.D.A.), NSF EAR-1714749 (to W.Y.), and Strategic Priority Research Program of CAS (XDB26000000) and NSFC 41661134047 (to J.L.). We thank the two anonymous reviewers for helpful comments that improved the quality of the manuscript.