In the vast plains of ancient South America, millions of years ago, a menacing shadow loomed over the grasslands. It wasn't a ...

This world is ancient. Scientists believe the world is billions of years old — with the exact number believed to be 4.5 billion years old. In that time, there have been many creatures roaming Earth.

There are plenty of terrifying animals alive today — grizzly bears, condors, boa constrictors, great white sharks and giant hornets, to name just a handful. But there are also some very scary ...

In the vast plains of ancient South America, millions of years ago, a menacing shadow loomed over the grasslands. It wasn’t a dinosaur or a mammalian predator, but a colossal bird that dominated the ...