A new small hyaenodon (Hyaenodonta: Hyaenodontinae) from the Eocene Lingbao Basin, Henan Province, China.

In this article, the discovery of Hyaenodon lingbaoensis, a new species of small Hyaenodontinae, is reported from the Middle Eocene Chuankou Formation in the Lingbao Basin of Henan province, China. The specimen is represented by a partial maxilla which preserves two deciduous premolars (DP3, DP4) and one molar (M1). The taxon can be assigned to Hyaenodon based on a "T-shaped" DP3; a small and low protocone on DP3-M1; and a buccolingually compressed and long metastylar blade on DP4-M1. The new taxon represents a basal Hyaenodon because it is more pleiomorphic than later members in having a M1 with a more developed paraconule and metaconule, a more enlarged protocone and less fused paracone and metacone. This finding casts new light on the early evolution of Hyaenodon and supports its Asian origin. Additionally, its deciduous and permanent premolars are described and new evidence regarding their replacement patterns of Asian Hyaenodon is provided.