Study: 2.5 billion T. rex roamed Earth, but not all at once
By SETH BORENSTEIN (AP) — One Tyrannosaurus rex seems scary enough. Now picture 2.5 billion of them. That’s how many of the fierce dinosaur king probably roamed Earth over the course of a couple million years, a new study finds. Using calculations based on body size, sexual maturity and the creatures' energy needs, a team at the University of California, Berkeley figured out just how many T. rex lived