Early Cretaceous mammals of Western Siberia: 2. Tegotheriidae

摘要

New specimens of the tegotheriid docodont Sibirotherium rossicum Maschenko et al., 2003, including a maxillary fragment with two posterior teeth, an isolated upper molar, and mandibular fragments with teeth from the Early Cretaceous Shestakovo locality are described. The dental formula of Sibirotherium is I(1 + ?)C1P(6)M(6?). The upper molars of Sibirotherium, with two main labial and three lingual cusps, are convergently similar to the molars of tribosphenic mammals. In the dentary, the symphysis is short and Meckel's groove is reduced. Sibirotherium is similar in the structure of lower teeth to Tegotherium from the Upper Jurassic of Mongolia; it is the latest known representative of Docodonta.