Didymoconidae is an enigmatic family of Asian Paleogene eutherian mammals, with its early diversity remaining poorly documented. Here, we report a new genus and species, Erlianoryctes mengi gen. et sp. nov., based on a fragmentary, partial juvenile skull and associated lower dentition recovered from the Arshanto Formation of the Erlian Basin, Nei Mongol, China. The new taxon is characterized by the combination of characters: P3 with a small metacone and prominent protocone; P4 submolariform, with the metacone incompletely separated from the paracone, and a distinct postcingulum present; M1–2 with a prominent postcingulum; and m1–2 with a relatively large and lingually positioned paraconid, and a tricuspid talonid in which the hypoconid, hypoconulid and entoconid are arranged in an arc. Morphological comparisons and phylogenetic analyses indicate that the new species represents a basal didymoconine, bridging Archaeoryctes-like ancestors and derived didymoconines. Additionally, the new specimen reveals a tooth eruption sequence virtually identical to that of later didymoconids, indicating that the tooth eruption pattern, except for the P2/p2, is probably conservative within the family.