Sloths weren’t always slow-moving, furry tree-dwellers. Their prehistoric ancestors were huge – up to 4 tons – and when startled, they brandished immense claws.
For a long time, scientists believed the first humans to arrive in the Americas soon killed off these giant ground sloths through hunting, along with many other massive animals like mastodons, saber-toothed cats and dire wolves that once roamed North and South America.
