Therapsids were widely distributed in Pangea in the late Permian. South Africa in Gondwana, and Russia in Laurasia are the principal areas recording tetrapods (including therapsids) of this age. More recent field explorations have increased the importance of Chinese late Permian fossil assemblages. This is clearly reflected in the discovery of several new therocephalians from the Naobaogou Formation in Nei Mongol. Here we report a therocephalian from that unit identified as a new species of the emblematic South African taxon Euchambersia. The new species, E. liuyudongi, is represented by a well-preserved skull and mandible showing a well-developed maxillary fossa and absence of postcanine teeth. This is the third akidnognathid recovered from the Naobaougou Formation, but oddly, the two basal Chinese akidnognathids previously known were recovered from a younger unit of the formation than the derived E. liuyudongi. This is the first time that the same therocephalian genus is recorded in northern and southern continents, making the record of the Naobaougou Formation key to understanding the evolution of late Permian continental faunas in general, and of akidnognathid therocephalians in particular.

The data matrix used for the phylogenetic analysis was originally presented by Liu & Abdala (2020). We introduce some modification deleting and adding some characters, changing wordings of characters and scorings. We add the scores of the new Chinese taxa Euchambersia liuyudongi and of Nothogomphodon sanjiaoensis. Modified, and deleted characters are presented in supplementary information file. The produce the matrix we used Mesquite (Maddison and Maddison, 2021). This matrix was transformed from Mesquite to a TNT matrix and the phylogenetic analysis was produced by TNT (Goloboff and Catalano, 2016).

Mesquite and TNT.