During South America's time as an isolated
island continent through much of the
Tertiary Period, many types of ungulates,
known as meridiungulates, evolved there.
They resembled various hoofed mammals in
other regions, such as horses, camels, pigs
and wild cattle. The litopterns, or 'simple
ankles', were mostly like camels and
horses, and showed the same trend to
fewer toes per foot, usually the odd
number of three or one. However, there
were differences from true horses in the
foot and ankle bones and, particularly, in
the paired lower leg bones, of radius/ulna
and tibia/fibula, which did not fuse as in
horses. Macrauchenia's-nostrils were high on
its skull, suggesting it may have had a trunk.
During South America's time as an isolated island continent through much of the Tertiary Period, many types of ungulates, known as meridiungulates, evolved there. They resembled various hoofed mammals in other regions, such as horses, camels, pigs and wild cattle. The litopterns, or 'simple ankles', were mostly like camels and horses, and showed the same trend to fewer toes per foot, usually the odd number of three or one. However, there were differences from true horses in the foot and ankle bones and, particularly, in the paired lower leg bones, of radius/ulna and tibia/fibula, which did not fuse as in horses. Macrauchenia's-nostrils were high on its skull, suggesting it may have had a trunk.
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