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A rhinoceros is any
of five surviving species of odd-toed ungulate in the family Rhinocerotidae.
All five are native to Africa or Asia. Rhinoceros is also one
of the genera in this family.Several other species became extinct
within geologically recent times, notably the Giant Unicorn and
the Woolly Rhinoceros in Eurasia: the extent to which climate
change or human predation was responsible is debated. Suffice
to say that they had survived many climate changes when modern
man arrived. Rhinoceros-like animals first appeared in the Eocene
as rather slender animals, and by the late Miocene there were
many different species. Most were large. One, Indricotherium weighed
about 30 tons and (so far as is known) was the largest terrestrial
mammal that ever lived. Rhinos became extinct during the Pliocene
in North America, and during the Pleistocene in northern Asia
and Europe.
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The five living
species fall into three tribes. The critically endangered Sumatran
Rhinoceros is the only surviving representative of the most primitive
group, the Dicerorhinini, which emerged in the Miocene (abut 20
million years ago). There are two living Rhinocerotini species,
the endangered Indian Rhinoceros and the critically endangered
Javan Rhinoceros, which diverged from one another about 10 million
years go. The extinct Wooly Rhinoceros of northern Europe and
Asia was also a member of this tribe. The two African species,
the White Rhinoceros and the Black Rhinoceros, diverged during
the early Pliocene (about 5 million years ago) but the Dicerotini
group to which they belong originated in the middle Miocene, about
14 million years ago. Rhinoceros horns are used in traditional
Asian medicine, and for dagger handles in Yemen and Oman. None
of the five rhinoceros species have secure futures: the White
Rhino is perhaps the least endangered, the Javanese Rhino survives
in only tiny numbers (estimated at 60 animals in 2002) and is
one of the two or three most endangered large mammals anywhere
in the world.
Images 1 Through
4 Are Courtesy Of US Fish & Wildlife Service
Images Number 5 Is Courtesy Of Tokyo University
Images Number 6 Of Courtesy Of The U.S.D.A.
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