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Africa was another big
continent were new mammals began to evolve. In fact, the elephant
first evolved in Africa; they spread to the continents only later.
One of the first mammals to evolve in Africa was a herbivore called
the Arsinoitherium. It looked like the rhinoceros and had two horns
side by side on its nose. These mammals lived nearly forty million
years ago.
The mammals of South
America remained cut off from the rest of the world for millions of
years. They, therefore, evolved into different kinds of unusual
creatures. Most of the marsupials from the region looked like the
opossum that we know today, feeding on smaller animals and on fruit.
Some of the prehistoric mammals included the fierce Thylacosmilus
that preyed on rare herbivores and the Thoatherium.
The Thylacosmilus had
long teeth that looked like daggers and which could stab through the
thickest hide. This was nature’s way of providing food to the
Thylacosmilus of South America, where some herbivores had very thick
coats and which the carnivores found difficult to tear apart. The
Thoatherium was like a horse in size. It had hoofs on its feet that
were even better suited for running on hard ground than those of a
horse.
The strangest of the
South American herbivores were the sloths. They could hang upside
down from the branches of trees. Though sloths are still alive
today, some of them gradually took to remaining on the ground,
moving awkwardly. These creatures, however, still maintain the long
curved claws that their ancestors had. The Megatherium was a ground
sloth that grew into a huge creature measuring six meters in length.
It weighed almost as much as an elephant and moved slowly. It had
sharp claws that it used to defend itself.
When South America
became connected with North America, nearly five million years ago,
some of the mammals from North America moved to the southern
continent. Used to the colder climate of the Northern Hemisphere,
these mammals were fierce and hardy. Many of the South American
mammals became extinct around this time. Some of them, such as the
opossum and the armadillo, moved to North America and they are still
surviving today. The Megatherium was one of the mammals that spread
into North America, but it became extinct a few thousand years ago. |
