Uintatherium

Uintatherium
Temporal range: Eocene, 52–37Ma
Cast, Museum National d'Histoire Naturelle, Paris
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Dinocerata
Family: Uintatheriidae
Genus: Uintatherium
Leidy, 1872
Species
  • U. anceps
  • U. insperatus Tong & Wang 1981
Synonyms
  • Dinoceras Marsh, 1872
  • Ditetrodon
  • Elachoceras
  • Octotomus
  • Tinoceras
  • Uintamastix

Uintatherium ("Beast of the Uinta Mountains") is an extinct genus of herbivorous mammal that lived during the Eocene epoch; two species are currently recognized, U. anceps from the United States during the Early to Middle Eocene, and U. insperatus of Middle to Late Eocene China.[1] Uintatherium went extinct about 37 million years ago, presumably due to climate change and competition with perissodactyls, such as brontotheres and rhinos.

Description

Restoration

Uintatherium was a large browsing animal. With a length of about 4 m (13 ft), a height of 1.70 m (5.6 ft), and a weight up to 2.25 tons, they were similar to today's rhinoceros both in size and in shape, although they are not closely related.[2] Its legs were robust to sustain the weight of the animal and were equipped with claws.[3] Moreover, unlike the rhinos today , the sternum was made up of segments of Uintatheres horizontal planes, and compressed and vertical segments.[4]

As with other early mammals of the Eocene epoch, Uintatherium didn't exactly excel in the intelligence department, with an unusually small brain compared to the rest of its bulky body.[5]

Skull

Cast of U. anceps skull, Museum National d'Histoire Naturelle of Paris

Its most unusual feature was the skull, which is both large and strongly built, but simultaneously flat and concave: this feature is rare and not regularly characteristic of any other known mammal except in some brontotheres. Its cranial cavity was exceptionally small due the walls of the cranium being exceedingly thick. The weight of the skull was mitigated by numerous sinuses permeating the walls of the cranium, like those in an elephant's skull.

The large upper canine teeth might have served as formidable defensive weapons, and superficially resembled those of saber-toothed cats. Sexually dimorphic, the teeth were larger in males than in females. However, they also might have used them to pluck the aquatic plants from marshes that seem to have comprised their diet.

The skulls of the males bore six prominent knob-like ossicones that grew from the frontal region of the skull. The function of these structures is unknown. They may have been of use in defense and/or sexual display.

Discovery

Skeleton of U. anceps at the National Museum of Nature and Science, Tokyo, Japan

Their fossils are the largest and most impressive of the finds at the excavation of Fort Bridger in Wyoming, and were a focal point of the Bone Wars between Othniel Charles Marsh and Edward Drinker Cope.

Fossils of U. anceps have been found in the Bridger and Wakashie rock formations, in the states of Wyoming and Utah near the Uinta Mountains, which are commemorated in the generic name. An almost intact skull of U. insperatus was found in the lower part of the Lushi Formation of the Lushi Basin in Henan Province, China.[1]

A cast of a Uintatherium skeleton is on display at the Utah Field House of Natural History State Park. The skeleton of Uintatherium is also on display at the Smithsonian National Museum of Natural History in Washington, DC.[6]

Extinction

Restoration of a female and male

As the Eocene period continued, large brontotheres such as Megacerops and primitive rhinos like Metamynodon began to appear on the landscape. In time these similar herbivores seem to have displaced dinoceratans like Uintatherium from their ecological niche, as so far no remains of Uintatherium have been found in late Eocene deposits.[7]

References

  1. ↑ 1.0 1.1 Tong, Yongsheng; Wang Jingwen (July 1981). "A SKULL OF UINTATHERIUM FROM HENAN" (PDF). Vertebrata Palasiatica XIX (3): 208–214.
  2. ↑ http://www.enchantedlearning.com/subjects/mammals/Iceagemammals.shtml
  3. ↑ Joseph Leidy (1873). "Contribution to the extinct vertebrate fauna of the Western Territories". Geological Survey of the Territories 1.
  4. ↑ Restoration of Dinoceras mirabile, de Charles Othniel Marsh
  5. ↑ "Uintatherium". About.com. Retrieved 7 November 2014.
  6. ↑ http://paleobiology.si.edu/geotime/main/htmlversion/evidence/eoc_02.html
  7. ↑ "Uintatherium". Prehistoric Wildlife. Retrieved 7 November 2014.

Further reading

Wikimedia Commons has media related to Fossil Uintatherium.