A research paper published yesterday says large ice age mammals may have gone extinct in northern Alaska when grassland turned to peat and rising sea levels covered the Bering Land Bridge.
Alaska and California researchers studied bones of ice age horses, steppe bison and woolly mammoths to determine why they died out.
Lead author Daniel Mann says the Earth’s environment was much more unstable during the ice ages and flipped back and forth every few thousand years.
He says during the times when grasslands were abundant large animals would have been attracted to northern Alaska.
Mann says when the Earth’s large ice sheets collapsed at the end of the last ice age, the melt led sea water to rise, which cut off a migration route back to Asia.