New discoveries from the Sinokannemeyeria-Shansisuchus Assemblage Zone: 2. A new species of Nothogomphodon (Therapsida: Therocephalia) from the Ermaying Formation of Shanxi, China.

LIU, J.; ABDALA, F.

Vertebrata Palasiatica

Chinese Academy of Science

Año: 2015 vol. 53 p. 123 - 132

1000-3118

A new therocephalian specimen collected from the upper part of the ErmayingFormation of Liulin, Shanxi, China is named as Nothogomphodon sanjiaoensis sp. nov. Thisnew species is differentiated from the type species Nothogomphodon danilovi by the followingcharacters: dentary lower margin uneven; canine base is ovate rather than rounded; distinctdiastema present between canine and first postcanine; absence of accessory cutting cuspson posterior border of the postcanines. Nothogomphodon has a postcanine morphology thatresembles that of sectorial toothed basal cynodonts, which is the only evidence of therocephalianshaving developed this kind of complex sectorial dentition. Faunal analysis between the RussianEryosuchus fauna and the Chinese Sinokannemeyeria-Shansisuchus Assemblage indicates thatonly Nothogomphodon is common to both faunas, whereas there is no common genus sharedbetween the Chinese Ermaying and Karamayi formations. Therocephalians were present at amoderate level of diversity in Middle Triassic faunas from Laurasia, whereas nonmammaliaformcynodonts are only represented by two taxa. Conversely, in Gondwana cynodonts experiencedan explosion in diversity in the Middle Triassic with the evolution of Gomphodontia, whiletherocephalians were scarcely represented in faunas of this age.