Sloths weren’t always slow-moving, furry tree-dwellers. Their prehistoric ancestors were huge – up to 4 tons – and when startled, they brandished immense claws. For a long time, scientists believed ...

Was Nanotyrannus a bona fide species or just a teenage Tyrannosaurus rex with a lot more growing to do? Scientists have settled that debate.

These findings line up with the fossil record. More than 90 percent of pygmy elephant remains are found within a narrow ...