Tyrannosaurus Rex is probably the most well-known dinosaur. Since its discovery just a little over a hundred years ago, it has been appearing in books, in movies, and on TV as a powerful villain in the dinosaur world. The name "tyrannosaurus rex" actually means "king of the cruel rulers."  That's a pretty difficult name to live up to though, especially when later discoveries showed us even bigger meat-eating dinosaurs.

The biggest of these meat-eaters currently known is the spinosaurus, which lived in and around North Africa millions of years before the first tyrannosaurus existed. Tyrannosaurus rex grew to about 45 feet long. Spinosaurus was up to 60 feet long! That's about two school buses in length!

So, the tyrannosaur wasn't the biggest or meanest. Dinosaurs probably weren't really mean, though. They just needed to eat to stay healthy.  Some animals eat plants, and others eat other animals. Some animals, like people, eat both!