The earliest people who lived in North America shared the landscape with huge animals. On any day these hunter-gatherers might encounter a giant, snarling saber-toothed cat ready to pounce, or a group of elephantlike mammoths stripping tree branches. Maybe a herd of giant bison would stampede past.
Obviously, you can’t see any of these ice age megafauna now. They’ve all been extinct for about 12,800 years. Mammoths, mastodons, huge bison, horses, camels, very large ground sloths and giant short-faced bears all died out as the huge continental ice sheets disappeared at the end of the ice age . What happened to them?
Scientists have pointed to various potential causes for the extinctions. Some suggest environmental changes happened faster than the animals could adapt to them. Others posit a catastrophic impact of a fragmented comet. Maybe it was overhunting on the part of humans, or some combination of all these factors.
