Abstract:
Four new taxa of the subfamily Brachyericinae, Exallerix manahan sp. nov. (Lower Oligocene of Mongolia), Synexallerix otus gen. et sp. nov. (Lower Miocene of eastern Kazakhstan), Postexallerix securis gen. et sp. nov. (Lower Miocene of Mongolia), and P. mustelidens sp. nov. (Middle Miocene of Mongolia) are described. E. manahan is similar in size and dental structure to Late Oligocene Metexallerix gaolanshanensis Qiu et Gu, 1988 from China; therefore, the latter species is transferred to the genus Exallerix, and Metexallerix is regarded as a junior synonym of Exallerix. "Metexallerix" junggarensis Bi, 1999 from the Lower Miocene of China is considered to be the type species of Synexallerix. The genus Synexallerix is proposed to be very similar to the ancestor of Miocene North American Brachyerix and Metechinus. The genus Postexallerix comprises the latest and most specialized Asian Brachyericinae characterized by a very narrow and long trigonid of M 1 and by a strongly reduced M 2. Phylogenetic relationships and adaptations of the Brachyericinae are discussed.
