A new symmetrodont mammal of the family Tinodontidae, Yermakia domitor gen. et sp. nov., from the Early Cretaceous Shestakovo locality (Kemerovo Region, Western Siberia) is described. This is the first record of "symmetrodonts" in Russia. Yermakia is characterized by a strongly deflected dentary, with a dorsally turned incisor region, a short mandibular symphysis, an anteriorly narrowing and posteriorly widening Meckel's groove, a well-pronounced pterygoid crest, a small pterygoid fossa, a laterally curved pterygoid flange, a gently sloping coronoid process of the dentary, four small lower incisors, a small double-rooted canine, a variably developed diastema between the canine and P₁, double-rooted P₁-P₃ lacking cusp b, and the trigonid angle increasing from 102° in M₁ and M₂ to 139° in M₄. The new symmetrodont from Shestakovo is intermediate in evolutionary development between Tinodon from the Late Jurassic of North America and Gobiotheriodon from the Early Cretaceous of Mongolia.