Feature Climate

Why won’t this debate about an ancient cold snap die?

Despite mainstream opposition, a controversial comet impact hypothesis persists

illustration of bison and mammoths

WHERE’D THEY GO? About 13,000 years ago, during the Pleistocene Epoch, bison, mammoths (illustrated) and other large mammals roamed North America. Researchers continue to argue over what caused their extinction.

Victor O. Leshyk

By Carolyn Gramling

- More than 2 years ago

Around 13,000 years ago, Earth was emerging from its last great ice age.