Before they were killed off by a meteor that hit Earth 66 million years ago, some 20,000 adults of the iconic ferocious dinosaur predator — Tyrannosaurus rex — roamed North America at any given time, researchers have calculated. Charles Marshall, a professor of integrative biology at the University of California, Berkeley, US, who led the research, said the work started with him wondering, when he held a T. rex fossil, how rare was that? So, for Tyrannosaurus rex, they had to not only plug in the weight of the dinosaur — which is about six tonnes, give or take a few — but also derive other numbers in the law. Dinosaurs are no longer thought to be cold-blooded like modern-day lizards, but they were probably not as warm-blooded as mammals. “But I can tell you what a good minimum is and what a good maximum is.”The calculations yielded a most likely standing population of 20,000 Tyrannosaurus rex adults.

Source: The Telegraph April 25, 2021 19:41 UTC