Eospalax, one of the only two extant genera within the Myospalacinae, has a high species richness. Each species is distinguished by unique cranial and dental morphologies, as well as variations in temporal and spatial distribution. Consequently, Eospalax serves as a reliable indicator for the biochronologic and paleoenvironmental studies of the Quaternary of East Asia. A recent discovery of a complete fossil skull in a conglomerate deposit, a part of the Lower Pleistocene Sanmen Formation, near Jianyucha Town, Zichang County, northern Shaanxi Province, has been subjected to a detailed analysis. The specimens were identified as Eospalax simplicidens, an extinct species of Eospalax, based on dental morphology. The recent discovery of E. simplicidens in Jianyucha offers significant insights into the species’ cranial morphology and contributes to a more comprehensive understanding of its geographical distribution. The distinctive feature of the posterodorsal location of the external acoustic meatus indicates either a plesiomorphy or an evolutionary convergence among E. simplicidens, African root rats (Tachyoryctes), and bamboo rats (Rhizomyini). A skull (IVPP V5398.1) and four upper jaws (V5398.2) from Gongwangling in Lantian, Shaanxi, previously identified as Myospalax fontanieri, is transferred to the species E. lingtaiensis. A skull (IVPP RV35055) from Jingou, Xin’an, Henan, previously identified as E. simplicidens, is transferred to the species E. youngianus. In this study, body mass estimates are made for extinct Eospalax. Both E. lingtaiensis and E. simplicidens are small-sized zokors, with an estimated body mass of less than or approximately 300 g, respectively.
