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Tapirs possess several conservative physical features, resembling the
earliest perissodactyls in several ways, notably retaining the ancestral
fourth digit on the front feet. Tapirs are forest animals and feed
on softer vegetation - they have not developed the cursorial adaptations
of the equids, nor the high-crowned teeth for grazing on grass. Infant
tapirs possess a striking pattern of white stripes and spots over their bodies,
providing camouflage for their first 5-8 months.
Tapirs have an unusual disjunct distribution - they are the only New World
perissodactyls (three species inhabit Central and South America), but one
species is native to Asia. The fossil record indicates this group evolved
in what is now North America, arising during the early Eocene and spreading
to Asia during the Miocene and to South America during the Pleistocene.
Subsequently, tapirs became extinct across most of North America, probably
due to climate change - southern Mexico is currently the most northern extent
of the range of Baird's tapir (Tapirus bairdii).
The family tree (below) is not fully resolved; while the American tapirs
would logically group together (as shown here), some genetic studies have
clustered the Baird's tapir (Tapirus bairdii) next to the Asian tapir
(Tapirus indicus), away from the other two American species.
The upper lip and nose of tapirs are extended into a short prehensile trunk,
which is one of the most recognizable features of this group.
To accommodate this proboscis, the nasal bones of the skull are short
and project forward. Tapirs retain the full eutherian complement of
teeth: the dental formula is I 3/3, C 1/1, P 4/4, M 3/3 x 2 = 44. |
