Uintatherium robustum 1872

Uintatherium (1) was the largest, most spectacular, and most bizarre animal discovered in the Eocene deposits near Fort Bridger, Wyoming. It's remains were a focal point in the bitter "bone wars" between Marsh and Cope. The dispute surrounding Uintatherium generated a rash of namings and publications by the two rivals as well as two publications by Leidy.

Uintatherium was discovered by Dr. Corson and Dr. Carter during Leidy's first visit to the Fort Bridger area in mid-July 1872 (2). After searching for fossils one day they returned to camp and showed Leidy their finds, which include a cranial fragment of a large skull, fragments from the upper and lower jaws (including some teeth), a nearly entire humerus (upper front leg bone) and fragments of other leg bones. A day earlier, the party had discovered a 9 inch fragment of a large fang. A letter describing the fragments, which Leidy named Uintatherium robustum, and the fang, named Uintamastix atrox, was soon sent to Philadelphia and read at a meeting of The Academy of Natural Sciences in late July. The publication date was set at August 1, 1872.

Meanwhile, both Marsh and Cope had also been combing the Fort Bridger area for fossils. Marsh presented a series of reports from late August to late September 1872 regarding four separate species of large mammals (Dinoceras mirabilis, D. lacustris, Tinoceras anceps, and T. grandis), while Cope reported his discovery of Loxolophodon cornutus (later renamed by Cope to Eobasileus cornutus) via a telegram during mid-August 1872. Both Marsh and Cope had more complete fossils that did Leidy. (3)

By the time he wrote his 1873 monograph on the Extinct Vertebrate Fauna of the Western Territories, Leidy had a chance to examine the nearly complete skull of Cope's Eobasileus (4), review Marsh's publications on Dinoceras and Tinoceras (5), and more closely examine his own fossils. The result was more than 20 pages of detailed descriptions of his fossil material and a discussion on the fossils described by Cope and Marsh.

Leidy quickly realized that the fang he named Uintamastix atrox, was in fact a tusk from Uintatherium. Leidy also concluded that Marsh's Dinoceras was the same animal as his Uintatherium robustum, while Cope's Eobasileus was a distinct, but closely related species. He suspected that Marsh's Tinoceras was also the same as Uintatherium, but felt he didn't have enough information to reach a firm conclusion. (6).

He knew that Uintatherium was unlike any known animal. The molars suggested that it was related to odd-toed ungulates such as the tapir, but this conclusion was contradicted by the paired horns on its skull. The structures of its vertebrae and massive limbs suggested that it was related to elephants, but its teeth did not. He tenatively regarded the animal as being most closely related to elephants, but stated that that determination would have to be made by Marsh, who had far more and far better specimens at his disposal (7).

Today, scientists are still puzzled by Uintatherium and its relatives, which are all known as uintatheres. They first appeared near the end of the Paleocene and became extinct by the end of the Eocene. They left no decendents and their relationship to earlier forms are still debated. They were once believed to have been restricted to North America, but additional species from East Asia were discovered in the 1980s. Uintatherium robustum was approximately 5 ft high (1.6 m) at the shoulders and 13 feet (4 m) long. It probably weighed more that 2 tons. It had three pairs of bony knobs on its skull and massive, elephant-like legs. Males have a pair of nearly 1 ft long (30 cm) tusks. It was an herbivore, or plant eater.

Websites:

• Joe Tucciarone's reconstruction of Uintatherium:
  www.joetucciarone.com/uint.html

Notes:

• Etymology:
  Uintatherium (you-IN-tah-THEER-ee-um) = uinta-beast (named after the Uintah Mountains in Utah)
  robustum (row-BUST-um) = robust [go back]
• Dr. James Van Allen Carter and Dr. Joseph K. Corson lived at Fort Bridger. Both were friends of Leidy and had sent him fossils for several years prior to Leidy's 1872 visit. For more information go to Leidy's Fossil Collectors. [go back]
• Leidy was able to examine Cope's Eobasilis skull while it was exhibited during a meeting of The Academy of Natural Sciences. [go back]
• Leidy usually had fewer, less complete, and more damaged fossils than did either Cope or Marsh. This was largely a result of the differences in collecting methods the three scientists employed. For more information, check out the page on fossil collecting. [go back]
• Marsh's 1872 reports on Tinoceras were short notices containing only a few sentences. His 1872 publication on Dinoceras included a brief but informative description of the skull and molars. Marsh also published additional descriptions of Dinoceras in 1873, as well as an illustration of its skull in 1873. [go back]
• For years, Marsh and Cope viciously contested the validity of each others' findings on these animals. Significantly, both failed to credit Leidy —or even mention him— except when they were denouncing each other's findings. Leidy's conclusions regarding the names of these animals were largely confirmed several decades later by Henry Osborn and William B. Scott. [go back]
• Marsh had by far the most extensive and most complete fossils of uintatheres. In 1887, he published a 237 page monograph entitled Dinocerata: a Monograph on an Extinct Order of Gigantic Mammals. It was a major contribution filled with detailed descriptions, numerous illustrations and reconstructions featuring nearly complete skeletons. Although virtually all of Marsh's species were later determined to be Leidy's Uintatherium robustum, the extent and quality of the information presented has prompted some modern experts to recognize Marsh's contribution by retaining his name for this group of extraordinary animals, Dinocerata. [go back]