Among the greatest mysteries of the tropical rainforest are the pooping habits of sloths. Really. Those furry, slow-moving tree dwellers almost never descend from the safety of the tree tops—except ...

Videos in India show that sloth bears seem unaware of being stalked by the ferocious felines. When the tigers try to strike, the bears often get the better of them. By Andrew Chapman In North America, ...

Ancient sloths lived in trees, on mountains, in deserts, boreal forests and open savannahs. These differences in habitat are primarily what drove the wide difference in size between sloth species. But ...