New Material on Small Hyenodons (Hyaenodontinae, Creodonta) from the Paleogene of Mongolia

A new species of Hyaenodontinae is described from a horizontal ramus of the mandible, the smallest Asian species of the subfamily, Hyaenodon pumilus sp. nov. from the upper Eocene of the Ergilin Dzo Formation of southwestern Mongolia. New specimens of H. chunkhtensis Dashzeveg, 1985 are described from the localities Khoer Dzan (Ergilin Dzo Formation, upper Eocene) and Tatal Gol (Shand Gol Formation, upper Oligocene). The specimens of H. chunkhtensis can be divided into two morphotypes.