The great Freeze and surviving of the creatures

Following the break up of the supercontinent Pangaea, mammals evolved differently on each landmass. Then, 15 million years ago, an ice cap began to form on Antartica and sea levels fell. This allowed animals to migrate between the different continents. it continued to get cloder until, about 3.25 million years ago, variations in the Earth's orbit were large enough to trigger the first of ice ages.

Adapt or die:

As the polar regions froze, the ice reflected sunlight back into space and the Earth cooled further. When the higher latitudes cooled, equatorial reqions became drier, forming the basis for the savannah grasslands and deserts of today. Though some mammals developed thick layers of fat or fur to keep warm, the changing climate led to the extiction of many species. But one group used its ingenuity to keep warm, clothung itself in the skins of others and lighting fires. These mammals were our own ancestors.