This is a relatively complete specimen of the left mandible of the giant Creodont from the Late Oligocene site, Meswa Bridge, dated between 22-19 million years. The specimen KNM-ME 20 is associated with various vertebra and limb bone fragments and includes a right maxilla with dentition too.
Hyainailourous evolves larger size towards the end of the late Oligocene perhaps in response to the increasing size of its prey, the Proboscidean anthracotheres.