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.

Giant sloths with razor-sharp claws and as large as Asian bull elephants once roamed the Earth, snacking on leaves at the tops of trees with a prehensile tongue. Now, scientists have figured out why ...

A sloth scientist, her tree-climbing BFF, and their dog work to save Costa Rica’s sloth populations. A sloth scientist, her tree-climbing BFF, and their dog work to save Costa Rica’s sloth populations ...

A sloth scientist, her tree-climbing BFF, and their dog work to save Costa Rica’s sloth populations in groundbreaking ways, all while capturing rarely seen wild sloth behaviors and reimagining what it ...