They Were 8,000-Pound Sloths With Claws and Armor – Then Humans Showed Up

Long before they became tree-hugging symbols of chill, sloths were 8,000-pound giants that roamed deserts, dug caves into cliffs, and even swam like manatees. Scientists have now pieced together the epic story of their evolution, using ancient DNA and hundreds of fossils to explain how sloths once grew to mammoth proportions—bigger than most cars—and why [...]