Sloths weren't always slow-moving, furry tree-dwellers. Their prehistoric ancestors were huge - up to 4 tons (3.6 metric tons ...

For a long time, scientists believed the first humans to arrive in the Americas soon killed off these giant ground sloths through hunting, along with many other massive animals like mastodons ...

Mastodons also resembled now-extinct mammoths with their long upper tusks, but were shorter and stockier. Rex Heuermann, a New York architect, is accused of killing Valerie Mack, who was last seen ...

A historic (or perhaps more accurately, prehistoric) discovery was made just under the surface of a New York homeowner’s lawn ...

A complete mastodon jaw was discovered in the backyard of a home in New York's Hudson Valley, marking the state's first such find in more than a decade, officials announced this week. The Stockton ...