Although it sounds like a grade-B science fiction movie, fossils show that our ancestors once hunted and fought giant ground sloths. For the first time, scientists have uncovered fossilized footprints ...

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. For a ...

Ancient sloths lived in trees, on mountains, in deserts, in boreal forests and on open savannas. Some grew as large as elephants. Illustration by Diego Barletta The largest sloth of all time was the ...