Sloths appear to have life figured out, and once the details are revealed, being envious makes sense. These tree-dwelling ...

In the tree, going clockwise from left: extinct West Indian sloth (Acratocnus), extant three-toed sloth or ai (Bradypus), and extant two-toed sloth or unau (Choloepus). From left to right on the ...

Sloths once roamed the Americas, ranging from tiny, cat-sized animals that lived in trees all the way up to massive ground sloths that may have weighed up to six tons. The only species we know and ...