(Even toothed beast).
Named By: Thomas Henry Huxley - 1870.
Classification: Chordata, Mammalia, Notoungulata, Toxodonta, Homalodotheriidae.
Species: H. segoviae. Possibly also H. cunninghami, H. crassum, H. excursom.
Size: 2 meters long.
Known locations: South America.
Time period: Early-mid Miocene.
Fossil representation: Several specimens.
notoungulate, Homalodotherium actually seems to
have been the South
American equivalent of the North American chalicotheres (mammals such
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
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.