ProboscideaFossil range: Late Paleocene - Recent |
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African Elephant |
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Scientific classification |
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Groups |
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Jozaria (extinct) Numidotheriidae (extinct) Barytheriidae (extinct) Phiomiidae (extinct) Deinotheriidae (extinct) Elephantiformes Palaeomastodontidae (extinct) Hemimastodontidae (extinct) Euelephantoidea Choerolophodontidae (extinct) Amebelodontidae (extinct) Gnathabelodontidae (extinct) Gomphotheriidae (extinct) Elephantidae Mammutidae (extinct) Stegodontidae (extinct) |
Proboscidea is an order containing only one
family of living animals, Elephantidae, the elephants, with three living
species (African Bush Elephant, African Forest Elephant, and Asian Elephant)[1].
During the period of the
last ice age there were more, now extinct species, including a number of
species of the elephant-like mammoths and mastodons. Further back in time, in
the late Tertiary, there were many more different types, including the bizarre
"shovel tuskers" like Platybelodon and Amebelodon. The
earliest known proboscidean is Phosphatherium dating from paleocene
deposits of Morocco. From the Eocene, several very primitive proboscideans are
known, including the African Numidotherium, Barytherium, Moeritherium
and the anthracobunidae from the Indo-Pakistanese subcontinent.
Paleontologists know of
about 170 fossil species which they classify as belonging to the Proboscidea
(Gr. proboskis, elephant's trunk, from pro, before, + boskein,
to feed) group. The oldest dates from the early Tertiary period, over 50
million years ago. A discovery in December, 2003 has forced a new estimate of
the age of elephant-like species to around 26 million years. Most of these
early elephants had four short tusks; two on the upper jaw and two on the
lower. Primelephas, the ancestor of mammoths and modern elephants,
appeared in the late Miocene epoch, about 7 million years ago. The evolution of
the elephant-like animals mainly concerned the proportions of the cranium and
jaw and the shape of the tusks and molar teeth.
1.
^ Shoshani,
Jeheskel (November 16, 2005). Wilson, D. E., and Reeder, D. M. (eds): Mammal
Species of the World, 3rd edition,
Johns Hopkins University Press, 90-91. ISBN 0-801-88221-4.
Mastodon |
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Mastodon skeleton |
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Conservation status |
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Pre |
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Scientific classification |
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Mastodons or Mastodonts are members of
the extinct genus Mammut of the order Proboscidea and form the family
Mammutidae; they resembled, but were distinct from, the woolly mammoth which
belongs to the family Elephantidae.
The American mastodon (Mammut
americanum) lived in North America. Mastodons first appeared almost four
million years ago and became extinct about 10,000 years ago, at the same time
as most other Pleistocene megafauna. Though their habitat spanned a large
territory, mastodons were most common in the Ice age spruce forests of Eastern
United States, as well as in warmer lowland environments.[1] Their
remains have been found as far as 300 kilometers offshore in Northeastern
United States, in areas that were dry land during the low sea level stand of
the last ice age.[2] There have been, however, findings of mastodon
fossils in South America and also on the Olympic Peninsula of Washington state.[3]
The tusks of the mastodon
sometimes exceeded five meters in length, and were nearly horizontal, another
contrast with more strongly curved mammoth tusks.[4] Young males had
vestigial lower tusks that were lost in adulthood.[4] The tusks were
probably used to break branches and twigs although some evidence suggests males
may have used them in mating challenges; one tusk is often shorter than the
other, suggesting that, like humans, mastodons may have had laterality.[4]
Examination of fossilized tusks revealed a series of regularly spaced shallow
pits on the underside of the tusks. Microscopic examination showed damage to
the dentin under the pits. It is theorized that the damage was caused when the
males were fighting over mating rights. The curved shape of the tusks would
have forced them downward with each blow, causing damage to the newly forming
ivory at the base of the tusk. The regularity of the damage in the growth
patterns of the tusks indicates that this was an annual occurrence, probably
occurring during the spring and early summer.[5]
The Mastadon is currently
extinct, unless you count the Mastodon Dinozord.
1.
^ Björn Kurtén and Elaine Anderson, Pleistocene
Mammals of North America, (New York: Columbia UP, 1980), p. 344.
2.
^ Kurtén and Anderson, p. 344.
3.
^ Kirk and Daugherty, Archaeology
in Washington, forthcoming from University of Washington Press, April 2007.
4.
^ a
b c
5.
^ Fisher,
D (Oct. 18-21, 2006). "Tusk cementum defects record musth battles in
American mastodons". Sixty-Sixth Annual Meeting of the Society
of Vertebrate Paleontology.
Wikipedia
http://en.wikipedia.org/w/index.php?title=Proboscidea&action=history
http://en.wikipedia.org/w/index.php?title=Mastodon&action=history
http://www.gnu.org/copyleft/fdl.html