Until the end of the last ice age, American cheetahs, enormous armadillo-like creatures and giant sloths called North America home. But it's long puzzled scientists why these animals and other megafauna — creatures heavier than 100 pounds (45 kilograms) — went extinct about 10,000 years ago.
Rapid warming periods called interstadials and, to a lesser degree, ice-age people who hunted animals are responsible for the disappearance of the continent's megafauna, according to a study published in 2015 in the journal Science. Other studies have placed more blame on humans, and some researchers say many factors are to blame.
