A new middle Eocene bunodont artiodactyl from the Erlian Basin (Nei Mongol, China)

A new genus and species of middle size bunodont artiodactyl (Mammalia), Erlianhyus primitivus, is established based on a partial maxilla with P3–M3 from the lower middle Eocene Irdin Manha Formation, Erlian Basin, Nei Mongol, China. Erlianhyus is characterised by a low tooth crown, bunodont cusps, a protocone smaller and lower than the paracone on P4, a large metaconule, reduced paraconule, no hypocone and styles on M1–3, and weak crista between the main cones on the upper cheek teeth. Erlianhyus is more similar in dental morphology to the Asian Myanmarius, Myaingtherium and Siamotherium rather than to other artiodactyls. Our cladistics analysis shows that Erlianhyus is positioned outside of the anthracotheriid-suoid-dichobunoid clade and is located more basally within the Artiodactyla, so now it is not referred to any known family or superfamily in artiodactyls.