Huge tunnels under southern Brazil and northern Argentina were potentially made by giant, Ice Age sloths for refuge and rest ...

Scientists from several countries have determined that mosasaurs, Cretaceous-era marine reptiles, once thrived in freshwater ...

And it was huge. The ancestor of today’s 20-foot great white shark was thought to be about 26 feet long, the authors of a ...

In the animal kingdom, the creatures with the biggest hearts – relative to their size – are often the tiniest among us.