Add Yahoo as a preferred source to see more of our stories on Google. New research finds shocked quartz at key sites, strengthening the case for a comet airburst during Ice Age extinctions. (CREDIT: ...

Almost 13,000 years ago, North America underwent drastic changes at a rapid rate. Mammoths, mastodons, giant ground sloths, and many other large animals went extinct. Around the same time, the Clovis ...