2.5 billion T. Rexe traveled to Earth, but not all at once: studying

A Tyrannosaurus rex looks pretty scary. Now imagine 2.5 billion of them. This is how many of the fierce dinosaur kings probably roamed the Earth over several million years, a new study shows.

Using calculations based on the body size, sexual maturity and energy needs of the creatures, a team from the University of California, Berkeley found out how many T. rex lived over 127,000 generations, according to a study in the journal Science. It is a unique number, but only an estimate with a margin of error that is the size of a T. rex.

“It’s a lot of jaws,” said the study’s lead author, Charles Marshall, director of the University of California’s Paleontology Museum. “There are many teeth. There are a lot of claws. ”

The species traveled to North America for about 1.2 million to 3.6 million years, which means that the population density of T. rex was low at all times. There would be about two in one place the size of Washington, DC or 3,800 in California, the study shows.

“Probably a lot of people, I literally did a double take to make sure my eyes weren’t wrong when I first read that 2.5 billion T. rexes have ever lived,” said Macalester College paleobiologist Kristi Curry Rogers, who was not part of the study.

Marshall said the estimate helps scientists calculate the conservation rate of T. rex fossils and highlights how lucky the world is to know about them. About 100 fossils of T. rex have been found – 32 of them with enough material to show that they are adults. If there were 2.5 million T. rex instead of 2.5 billion, we probably never knew it existed, he said.

Marshall’s team calculated the population using a general rule of general biology that says that the larger the animal, the less dense its population is. Then they added estimates of the amount of energy the carnivore T. rex needed to stay alive – somewhere between a Komodo dragon and a lion. The more energy is needed, the less dense the population. They also took into account the fact that T. rex reached sexual maturity somewhere between 14 and 17 years and lived to a maximum of 28 years.

Given the uncertainties about the length of the creature generation, range and how long they traveled, the Berkeley team said the total population could reach 140 million or even 42 billion, with an average of 2.4 billion.

The science of the largest land-dwelling carnivores of all time is important, “but the truth, as I see it, is that this kind of thing is very cool,” said Purdue University professor of geology James Farlow.