Sloths seem like they should be some of the easiest mammals on Earth to study, but researchers quickly discover the opposite.

Sloths are notoriously difficult to study in the wild. From their hidden lives high in rainforest canopies to their slow movements and remarkable camouflage, here’s how scientists track, study and ...

Today, sloths are slow-moving, tree-dwelling creatures that live in Central and South America and can grow up to 2.5 feet long. Thousands of years ago, however, some sloths walked along the ground, ...