A distribution of a T. rex skeleton on display in front of the UC Museum of Paleontology at the University of California, Berkeley. The original, an almost complete skeleton excavated in 1990 from the hardlands of eastern Montana, is in the Rock Museum in Bozeman, Montana.
Keegan Houser, UC Berkeley
Humans in our current form have existed for several hundred thousand years, which seems to be an inconceivably long duration compared to the lifespan of a single man. But even more amazing is the fact that, long before we appeared, Tyrannosaurus rex took place more than 10 times more.
Now, a new study is trying to calculate exactly how many frightening and thundering lizards could have stepped on Earth in a few million years. The result: probably about 2.5 billion in total, but the number could reach 42 billion.
This peak number is probably less than half the total number of people who have ever lived, but it is still a lot of huge, hungry prehistoric predators, especially when we consider what is relatively rare to find T. rex fossils for paleontologists. .
“There are about 32 relatively well-preserved post-juvenile rexes in today’s public museums,” Charles Marshall, director of the University of California’s Paleontology Museum, said in a statement. “Of all the post-juvenile adults who have ever lived, this means that 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 missing animals in computer simulations to make, in essence, educated assumptions about their total numbers.
The billions of towering carnivores that live over several million years are still a much lower population density than humans today, of course. The study estimates that the total population of T. rexes at one time was probably about 20,000 adults. Clearly nothing compared to the nearly 8 billion bags of human flesh that hang today.
But Marshall and his colleagues at UC Berkeley estimate a population density of about one dinosaur per 100 square kilometers. This means that, statistically speaking, during the late Cretaceous you could have expected a T. rex to be about 11.3 kilometers from your location. Not exactly a safe environment for many trips.
However, there is a lot of uncertainty in the estimates that Marshall and his team came up with. While the simulation found 2.5 billion T. rexes in total as the best assumption, the correct figure could actually be somewhere in the wide range between 140 and 42 billion.
“In some ways, it’s been a paleontological exercise in how much we can know and how we strive to know it,” Marshall said. “It is surprising how much we actually know about these dinosaurs and, from this, how much more we can calculate. Our knowledge of T. rex has expanded so much in recent decades due to more fossils, more ways to analyze them, and better ways to integrate information on multiple known fossils. ”
The team also provides the computer code used in the research, which it hopes will allow paleontologists to estimate how many other species could be missed in the excavations.
“With these figures, we can begin to estimate how many short-lived, geographically specialized species we may be missing from fossil records,” he said. “This can be a way to start quantifying what we don’t know.”
One thing is certain for at least one person: putting a quantity in the historical number of T. rexes brings certain nightmares into a clearer concentration.