Name:
Homalodotherium
(Even toothed beast).
Phonetic: Ho-mal-o-do-fee-ree-um.
Named By: Thomas Henry Huxley - 1870.
Classification: Chordata, Mammalia,
Notoungulata, Toxodonta, Homalodotheriidae.
Species: H.
cunninghami.
Diet: Herbivore.
Size: 2 meters long.
Known locations: South America.
Time period: Early-mid Miocene.
Fossil representation: Several specimens.
Although
a
notoungulate, Homalodotherium actually seems to
have been the South
American equivalent of the North American chalicotheres (mammals such
as Chalicotherium
and Tylocephalonyx.
This idea is based around the
observations that the fore limbs are digitigrade with specially
well-developed muscles and ranges of motion while the rear limbs are
plantigrade and better suited for support. Together these suggest
that while Homalodotherium was almost certainly
quadrupedal when
walking, it could probably support its weight on just its hind
quarters while using the fore limbs to reach into the tree canopy.
Additional
support for this
browsing lifestyle comes from the fact that Homalodotherium
had claws
instead of hooves like most other notoungulates, features that could
be used to hook around branches to pull them down. The nasal bones
are also located high and back of the snout rather than on the tip,
something that may indicate the presence of a short proboscis like a
trunk, or perhaps a prehensile lip. Again either adaptation would
give Homalodotherium an advantage when feeding from
trees.
If
the above theory about the
feeding strategy of Homalodotherium is true then it
also means that it
anticipated the large ground sloths such as Megatherium
and
Nothrotheriops
that appeared much later. This similarity with ground
sloths and chalicotheres is yet another case of how a South American
mammal had developed similar adaptations to a near identical lifestyle
despite South America being isolated from the rest of the world at the
time.