(AP) — A new study concludes that 2.5 billion Tyrannosaurus rex prowled North America.
Thursday's study said they didn't all roam Earth at once. That's over a couple million years or so. And at any one moment, maybe 20,000 or so were alive.
The study figures out the T. rex population based on its size, how much it had to eat and its sexual maturity.
It’s a first-of-its-kind estimate, though it comes with a huge margin of error. Scientists say if there were much fewer T. rex, we may never have known they existed.
Only about 100 or so T. rex fossils have been found.
