Category: Dinosaur

Uintatherium was a large, rhinoceros-like plant-eating mammal that lived during the Eocene epoch roughly 40 million years ago. The most striking feature of these beasts were the six bony knobs on their unusual skulls.



Genera and Species

Kingdom - Animalia

Phylum – Chordata

Class – Mammalia

Order – Dinocerata

Family – Uintatheriidae

Genus – Uintatherium

Species – U. anceps, U. insperatus

Name Meaning – “Beast of Uinta (Mountains)”


Uintatherium was very large animal, and was largely similar to the rhino of today, although they were not closely related. However, Uintatherium possessed many features not found in rhinos, including clawed feet and bony knobs on its skull instead of horns. These knobs were known as ossicones. Uintatheres also possess large upper canine teeth that protruded like tusks, though the rest of their teeth were quite small and were more like rabbit’s teeth than those of other modern day large herbivores. The structure of their snouts is a subject of debate among paleontologists. Some originally believed they may have had an elephant-like trunk, though now most scientists favor the idea that they possessed a fleshy lip like a hippopotamus or rhinoceros. The structure of their lower jaw also suggests they may have had long, prehensile tongues like the modern giraffe.


Height – 5.6 ft. (1.7 meters)

Length – 13 ft. (4 meters)

Weight – 4400 lbs. (2 metric tons)


Uintatheres were typically the largest creatures on land for much of their existence, and probably had little to fear from predators. The largest animals that could pose a threat were likely Hyaenodonts, who did not grow much larger than wolves in areas the Uintatherium called home. Their skull knobs and tusks were most likely used in combat between males over potential mates, rather than to protect them from other animals.

The Uintatherium may have had a fermentation chamber in its stomach to help it digest its food, similar to a cow. Its small teeth likely could not chew its food enough to allow it to fully digest. Some paleontologists believe its behavior may have been similar to hippopotamuses, and may have spent much of its time in an aquatic environment.

History of Discovery

The relationship between Uintatheres and other mammalian groups is not well understood. They share characteristics with many other mammal orders, but no direct link has been established. They lived until the late Eocene epoch and when their jungle habitats began to disappear, so did Uintatherium.

The first Uintatherium fossils were discovered in the thick of the “Bone Wars” between early paleontologists Othniel Marsh, Edward Drinker Cope, and Joseph Leidy. All were exploring the same area and when each discovered numerous Uintatherium skulls, they all attempted to claim bragging rights over being the first to name and describe them. Thus, there are many obsolete synonyms including Dinoceras, Tinoceras, and Loxolophodon. Leidy was the first to get his find published, which is why Uintatherium is the currently accepted name for the genus.


  1. The Princeton Field Guide to Prehistoric Mammals, Donald R. Prothero, 2017.

  2. https://en.wikipedia.org/wiki/Uintatherium