In the vast tapestry of prehistoric life, certain creatures stand out for their sheer size and fascinating adaptations. Among these is the Megatherium, a genus of giant ground sloths that once roamed ...

SAO PAULO — Sloths weren’t always slow-moving, furry tree-dwellers. Their prehistoric ancestors were huge — up to 4 tons (3.6 metric tons) — and when startled, they brandished immense claws.