Scientists Have Figured Out How Extinct Giant Ground Sloths Got so Big and Where It All Went Wrong

Why Ancient Sloths Became the Size of Elephants—and Then Vanished

Scientists figured out why this evolutionary strategy didn’t work out.

8,000-pound sloths once roamed North America. Where'd they go?

Giant sloths used to roam all over North America. Over 10 times bigger than today’s sloths, many lived on the ground instead of in the trees and their closest living relatives are actually armadillos and anteaters. The largest of these ancient animals were those in the genus Megatherium–roughly the size of a modern Asian bull elephant and weighed about 8,000 pounds. But how did they grow so large–and why did they shrink down? A new analysis of o…

Giant ground sloths evolved three different times for the same reason

An analysis of the sloth family tree suggests three different groups of the animals evolved to gigantic sizes in response to cold and dry conditions

Scientists have figured out how extinct giant ground sloths got so big and where it all went wrong

Most of us are familiar with sloths, the bear-like animals that hang from trees, live life in the slow lane, take a month to digest a meal and poop just once a week. Their closest living relatives are anteaters and armadillos, and if that seems like an odd pairing, there's a reason why. Today, there are only two sloth species, but historically, there were dozens of them, including one with a bottle-nosed snout that ate ants and another that like…