Abstract
Symplokeomys zaysanicus is a new genus and species of eomyid rodent from the upper part of the Aksyir Formation of the Zaysan Basin, eastern Kazakhstan. The new taxon differs from other eomyids in having a complex pattern of interconnecting lophules within the central basin of its cheek teeth. Other mammals from the Aksyir Formation indicate an Ergilian (late Eocene) age.