See text Dinocerata (from the Greek δεινός (deinós), "terrible", and κέρας (kéras), "horn") or Uintatheria,[1] also known as uintatheres, is an extinct order of large herbivorous hoofed mammals with horns and protuberant canine teeth, known from the Paleocene and Eocene of Asia and North America.

With body masses ranging up to 4,500 kilograms (9,900 lb) they represent some of the earliest known large mammals.

[2] Over the course of their evolution, dinoceratans underwent a great increase in body size, from a weight of 175 kilograms (386 lb) in the earliest species to a weight of up to 4,500 kilograms (9,900 lb) in the largest species, co-inciding with the development of fully graviportal limbs with a digitigrade posture.

[2] The oldest and most primitive members of the group, such as Prodinoceras, appeared virtually simultaneously during the late Paleocene in North America and Asia, indicating connection between the two landmasses, with uintatheres continuing to exchange between the landmasses during the Eocene, as suggested by the presence of Uintatherium in both North America and China.

A 2015 phylogenetic study recovered Dinocerata as part of Laurasiatheria, closely related to ungulates and "condylarths", with Dinocerata placed as the sister group to the South American native ungulate group Xenungulata.