Uintatherium
Name:
Uintatherium
(Uinta beast - after the Uinta Mountains).
Phonetic: Win-tah-fee-ree-um.
Named By: Joseph Leidy - 1872.
Synonyms: Dinoceras, Ditetrodon,
Elachoceras, Octotomus, Tinoceras, Uintamastix, Uintatherium
atrox, U. alticeps, U. furcatus, U. latifrons, U.
leidianum, U. princeps, U. pressicornis, U. robustum?,
U. segne, U. vagans.
Classification: Chordata, Mammalia, Dinocerata,
Uintatheriidae.
Species: U. anceps (type), U.
insperatus, U. robustum?.
Diet: Herbivore.
Size: 4 meters long.
Known locations: China, Henan Province - Lushi
Formation. USA - California, Texas, Utah, Wyoming.
Time period: Ypresian to Bartonian of the Eocene.
Fossil representation: Many specimens.
Imagine
a
rhinoceros with several smaller horns on top of its head and forward
teeth similar to a sabre-toothed cat and you have a rough idea to what
Uintatherium looked like. Although first named by
Joseph Leidy in
1872, Uintatherium would become involved in the
‘bone wars’, a
well-publicised feud between the palaeontologists Othniel Charles Marsh
and Edward Drinker Cope. These two palaeontologists were constantly
trying to outdo one another in terms of discoveries and the naming of
new prehistoric animals, but often each would end up with the remains
of the same type of animal, but each would give it their own name of
choice and refuse to acknowledge the validity of the others name.
As
far as Uintatherium is
concerned Leidy was the first to name it, but both Marsh and Cope
came into possession of further remains and subsequently provided their
own names. Because both Marsh and Cope were both blinded by their
desire to outdo one another, neither recognised the reality that they
had described a creature that had already been named. As time
progressed however, the true realisation of this mess was found by
the wider palaeontological community, and Marsh’s and Cope’s names
today exist only as synonyms to Uintatherium. One
further element of
confusion however is that a lot of species have been assigned to the
Uintatherium genus in the past, partly because of
this. Even
further study has since found these species only represent a single
species and while some of these are still very occasionally mentioned
as recently as the early twenty-first century, only the type species
of U. anceps is universally recognised by all. U. robustum is sometimes mentioned as valid, and an
additional species, U. insperatus, is known from
China.
Although
Uintatherium is
quite well known in terms of fossils, there continues to be
uncertainty as to which mammals it is more closely related to. In
terms of form Uintatherium is similar to a rhino,
but it is not
considered to be related because other primitive rhinos of the early
and mid-Eocene were typically very small and different to the rhinos we
know today. A recurring theory that is not widely accepted however is
that Uintatherium, as well as the other
dinoceratans, is related to
the Anagaloidea group of mammals which are thought to be the ancestors
of the lagomorphs (rabbits, hares) and rodents (mice,
rats). Most however today consider Uintatherium
to be an
ungulate, or hoofed mammal, but exactly how it fits in to other
ungulates is still not certain. Uintatherium will
continue to be
studied in the future, and possibly further discoveries of similar
animals may yet help to provide further information for
palaeontologists to work from.
The
most instantly
recognisable features of Uintatherium are the three
pairs of horns that
project upwards from on top of its head. The first pair were on the
tip of the snout, the second between the eyes and the nostrils, and
the third almost on the back of the skull. Palaeontologists are
confident in ascertaining that these horns were for display in
attracting mates as they are only present on the males. A further
suggestion has been made that the horns may have been used in contests
between two males in a similar manner to how male deer use their
antlers. It is certainly feasible since a larger number of smaller
horns would be more capable of locking with an opposing animal, and a
mature and proven individual with possibly slightly larger horns would
have an advantage over a younger and less well developed individual.
A
further sign of sexual
dimorphism are the enlarged upper canine teeth which appear to have
been larger in the males, something that has led some to the
conclusion that Uintatherium males may have bitten
each other in
dominance contests, although it’s possible that it could have been
additional display. In life these enlarged teeth are thought to have
been used in feeding, either for rooting up buried plant parts, or
perhaps even for pulling out large amounts of aquatic plants. The
other teeth in the mouth were relatively small and not suited for
processing tough vegetation, something which implies that
Uintatherium had to specialise in eating soft
vegetation that could
have been eaten without extensive processing in the mouth.
One
interesting feature about
Uintatherium is that it had a concave skull, which
means that it
dipped inwards instead of outwards like in most other animals.
Combined with the thick walls of the skull, this would have reduced
the cranial cavity that resulted in a smaller brain size. By today’s
standards of mammalian intelligence, Uintatherium
didn’t even come
close, and was probably restricted to certain set patterns of
behaviour. However Uintatherium like other
animals would only need to
be intelligent enough to adapt to its environment, and with a
temporal range of approximately fifteen million years, it was more
successful than many other animals in this.
As
the Eocene period
progressed, 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.
Further reading
- The problem of the Uintatherium molars. -
Bulletin of the American
Museum of Natural History ; v. 48, article 18. - Horace Elmer Wood -
1923.
- A Skull of Uintatherium from Henan - Vertebrata
Palasiatica XIX (3):
208–214. - Yongsheng Tong & Wang Jingwen - 1981.
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