Counting T. Rexes
April 23, 2021
More than 2 billion Tyrannosaurus rexes walked the Earth. That’s according to a new study published in the journal Science.
The reptiles were not all alive at the same time. They were around for about 1 million to 4 million years, about 70 million years ago. There may have been about 20,000 adult T. rexes at any one time.
Only about a hundred T. rex fossils have been found. Researchers arrived at the number 2 billion by looking at key facts about T. rex, including its average body size and energy needs.
Experts were surprised by the estimate. Charles Marshall is a biology professor at the University of California, Berkeley. He’s also the study’s lead author. “That’s a lot of jaws,” he says. “That’s a lot of teeth. That’s a lot of claws.”