| Noun | 1. | Uintatheriidae - an extinct family of Dinocerata mammal family - a family of mammals Dinocerata, order Dinocerata - small order of primitive ungulates of the Paleocene and Eocene genus Uintatherium, Uintatherium - type genus of the Uintatheriidae; extinct large herbivorous ungulates somewhat resembling elephants; from the Eocene in Wyoming |