Gliridae and Eomyidae (Rodentia) of the Miocene Tagay fauna (Olkhon Island, Lake Baikal, Eastern Siberia).

The s mall mammals Myomiminae indet. (Gliridae), Leptodontomys cf . gansus Zheng and Li, 1982 (Eomyidae) and the new species Keramidomys sibiricus nov. spec . (Eomyidae) are described. They were collected from six layers of the middle to upper part of the Tagay-1 section on Olkhon Island. The glirid Myomiminae indet. is represented by only a few isolated teeth, the small eomyid Leptodontomys cf . gansus by a mandible with two teeth, and the second small eomyid Keramidomys sibiricus nov. spec . by several isolated teeth and a mandible. The ancestral tooth characteristics of Keramidomys sibiricus nov. spec . indicate an early evolutionary stage of Keramidomys in Asia. The suggested age of the assemblage is Early/Middle Miocene transition.