Researchers analyzed fossils and DNA to get a big-picture view of sloth evolution and determine what drove their immense size ...

An analysis of the sloth family tree suggests three different groups of the animals evolved to gigantic sizes in response to ...

Ground sloths varied widely in size, from the truly massive Megatherium—which could rip foliage off the tops of trees with its prehensile tongue and acted as a sort of ecological stand in for ...