An occupation of a T. rex skeleton outside the UC Museum of Paleontology at the University of California, Berkeley. The original, an almost complete skeleton excavated in 1990 from the badlands of eastern Montana, is in the Museum of the Rockies in Bozeman, Montana.
Keegan Houser, UC Berkeley
Humans in our current form have been around for hundreds of thousands of years, which seems like an unimaginable long term compared to the lifespan of a single human. But even more surprising is the fact that Tyrannosaurus rex was going on for more than ten times as long long before we emerged.
Now a new study is trying to calculate exactly how many of the frightening, thundering lizards may have bumped over the Earth in a few million years and pushed them away. The result: probably about 2.5 billion, but the number could actually be as much as 42 billion.
This high number is probably less than half the total number of people who have ever lived, but it is still a large number of hungry, prehistoric predators, especially when we consider what a relatively rare T. rex fossil is. for paleontologists.
“There are about 32 relatively well-preserved, post-juvenile T. rexes in public museums today,” Charles Marshall, director of the Museum of Paleontology Museum of California, said in a statement. “Of all the adults who still lived after youth, that means we have about one in 80 million of them.”
Marshall led the study, published in the latest issue of the journal Science, which fed known data on extinct animals in computer simulations to essentially educate them about their total number.
Billions of high carnivores living over several million years are, of course, still a much lower population density than those of humans. The study estimates that the total population of T. rexes at any given time was probably about 20,000 adults. This is clearly nothing compared to the nearly 8 billion human meat bags hanging around today.
But Marshall and his UC Berkeley colleagues estimate a population density of about one dinosaur per 100 square miles. This means that statistically speaking, during the late Cretaceous period, you could expect a T. rex to be within 11.3 kilometers of your location. Not exactly a safe environment to travel a lot.
However, there are many uncertainties in the estimates that Marshall and his team came up with. While the simulation found 2.5 billion total T. rexes as the best guess, the correct figure could actually be somewhere between 140 million and 42 billion.
“In some ways, it was a paleontological exercise in how much we can know and how we go about knowing it,” Marshall said. “It’s amazing how much we actually know about these dinosaurs, and how much more we can calculate. Our knowledge of T. rex has expanded so strongly over the past few decades thanks to more fossils, more ways to analyze them, and better ways to learn about integrate the multiple fossils. ”
The team also obtained the computer code used in the research, which they hope paleontologists can estimate how many other species could be missed during excavations.
“With these numbers, we can begin to estimate how many short-lived, geographically specialized species we could miss in the fossil record,” he said. “It could be a way to start quantifying what we do not know.”
One thing is for sure for at least one person: putting a quantity to the historical number of T. rexes brings certain nightmares sharper into focus.