Paleontologists at the University of California, Berkeley, tried to give a number of how many T. rex lived during the Cretaceous – about 65 million to 98 million years ago – knowing that this would not be an easy task.
Fossils have long been used to deepen our understanding of extinct creatures such as dinosaurs, but experts believe that it may be difficult to use these remains to calculate population density and abundance.
“There is simply no information to make the estimate,” explained Charles Marshall, director of the Museum of Paleontology Museum of California, which was part of the research team. “If you find an Easter egg in your garden, how can you estimate how many Easter eggs have already existed? It simply cannot be done. You need information from somewhere else – for example the density of Easter eggs, the area to which eggs go. can be found, and how many years have Easter eggs been laid in gardens. ‘
“Previously, researchers have tried to estimate things like the probable size of Tyrannosaurus’ home range and its basic energy needs. So it’s a neat extension of previous work, and it contains a lot of updated information about Tyrannosaurus,” said Nizar Ibrahim, paleontologist at the University of Portsmouth (UK) and National Geographic Explorer, who were not part of the research.
“We just have to keep in mind that all these interesting studies have a certain amount of uncertainty – there is just so much we don’t know about dinosaurs yet, even a Hollywood star like T. rex,” Ibrahim added. n e-mail.
20,000 T. rex at any one time in North America
The UC Berkeley team used the fossil record, density data and climate model data to calculate that about 20,000 adult T. rex, which lived throughout North America, probably always existed. This is what the researchers say in a study published in the journal Science, meaning that about 2.5 billion of the predators lived and died during the approximately 2.5 million years in which the dinosaurs lived.
For the first time, the team also calculated the lifespan of the dinosaur: Using scientific literature and expert advice, they estimated that the probable age of sexual maturity for a T. rex was 15.5 years and that the lifespan up to the late 20s could stretch. The dinosaur’s average body weight for adults was about 5,200 kg (11,464 pounds), and a growth storm on sexual maturity could send them up to 7,000 kg (15,432 pounds).
From these estimates, the team concluded that each generation of T. rex lasted about 19 years, with one dinosaur for every 100 square kilometers.
With a permanent population of 20,000 of the dinosaurs, and with approximately 127,000 generations of the species, there would be 2.5 billion dinosaurs, the team determined.
The researchers’ methods’ appear to be very informative, while also showing the current limits of what can be done with what we now know, ‘said Jason C. Poole, chief fossil preparer at Bighorn Basin Paleontological Institute and a paleontological artist. part of the study.
“I’m sure it will open doors to concentrate even better on the issues of population density and what it means over time,” Poole added in an email. “It can therefore help to understand things like change in a species over time, as it is related to evolution and changing ecosystems.”
The study authors estimate that the population density of the species is equal to 3,800 of the carnivorous dinosaurs in an area as large as California – but only two in an area as large as Washington DC.
T. rex fossils are rare
Meanwhile, the results also enabled the authors of the report to determine that only about 1 in 80 million T. rex are preserved as fossilized remains.
“The great impact of this study may be that it shows how rare fossils are, in that they represent only a small fraction of the individual organisms that existed, not to mention the depth of time, just as in ‘ a few thousand to a million years, ‘Poole said.
“In some ways, it was a paleontological exercise in how much we can know and how we go about knowing it,” said Marshall, co-author of the study and UC Berkeley professor of integrative biology, and of Earth. and planetary science, said in a statement. .
“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 them. to integrate the multiple fossils, ‘he said.
Outside the T. rex
Ibrahim sees other possibilities arising from this study.
“There are many things we do not know about the physiology, behavior and nutritional ecology of Tyrannosaurus, but this study offers an interesting approach to estimating the quantity and conservation rate of dinosaurs,” he said.
“I would like to see it applied to other dinosaurs known from abundant fossils. If we look at a wider variety of dinosaurs – predators and prey – it could enable us to better compare animal communities of dinosaurs to modern ones. .
“But we are just scratching the surface, and even with this intriguing study, there is still a long way to go before we can confidently apply such approaches more widely to the study of dinosaurs.”