Paleontologists from the University of California, Berkeley, set out to place a quantity on how many T. rex lived through the Cretaceous interval — about 65 million to 98 million years in the past — understanding that it would not be a easy activity.

Fossils have lengthy been used to deepen our understanding about extinct creatures equivalent to dinosaurs, however consultants say it may be difficult to make use of these stays to calculate inhabitants density and abundance.

“There is just no information to make the estimate,” defined Charles Marshall, director of the University of California Museum of Paleontology, who was a part of the analysis group. “If you find an Easter egg in your garden, how can you estimate how many Easter eggs that have ever existed? It simply can’t be done. You need information from somewhere else — for example, the density of Easter eggs, the area over which eggs might be found, and for how many years Easter eggs have been placed in gardens.”

“Previously researchers have tried to estimate things like the likely home range size of Tyrannosaurus, and its basic energetic needs, so this is a neat extension of previous work, and it includes lots of updated information on Tyrannosaurus,” mentioned Nizar Ibrahim, paleontologist on the University of Portsmouth (UK) and National Geographic Explorer, who was not a part of the analysis.

“We just have to keep in mind that all of these intriguing studies come with a certain dose of uncertainty — there is just so much we still don’t know about dinosaurs, even a Hollywood star like T. rex,” Ibrahim added in an e-mail.

20,000 T. rex in North America at anybody time

Using the fossil file, density knowledge and knowledge from local weather fashions, the UC Berkeley group calculated that roughly 20,000 grownup T. rex, which lived all through North America, in all probability existed at anybody time. This, the researchers say in a research revealed in the journal Science, implies that some 2.5 billion of the predators lived and died over the roughly 2.5 million years throughout which the dinosaurs lived.

For the primary time, the group additionally calculated the longevity of the dinosaur: Using scientific literature and knowledgeable opinion, they estimated that the seemingly age of sexual maturity for a T. rex was 15.5 years, and its lifespan might attain into the late 20s. The dinosaur’s common grownup physique mass was round 5,200 kilograms (11,464 kilos), and a progress spurt at sexual maturity might ship them to 7,000 kilograms (15,432 kilos).

From these estimates, the group got here to the conclusion that every era of T. rex lasted for round 19 years, with there being one dinosaur for each 100 sq. kilometers (38.6 miles).

Researchers discover a dinosaur preserved sitting on a nest of eggs with fossilized embryos, a firstResearchers discover a dinosaur preserved sitting on a nest of eggs with fossilized embryos, a first

With a standing inhabitants of 20,000 of the dinosaurs, and with some 127,000 generations of the species, there could be 2.5 billion dinosaurs total, the group decided.

The researchers’ strategies “seem to be very informative while also showing the present limits of what can be done with what we now know,” mentioned Jason C. Poole, head fossil preparator at Bighorn Basin Paleontological Institute and a paleontological artist, who was not a part of the research.

“I am sure it will open doors for getting even better focus on the questions of population density and what that means over time,” Poole added in an e-mail. “So really this could help understand things like change in a species over time as it relates to evolution and changing ecosystems.”

The research authors estimate that the inhabitants density of the species equated to three,800 of the carnivorous dinosaurs in an space the dimensions of California — however solely two in an space the dimensions of Washington DC.

T. rex fossils are uncommon

Meanwhile, the outcomes additionally allowed the report authors to find out that solely about 1 in 80 million T. rex are preserved as fossilized stays.

“The great impact of this study may be that it shows just how rare fossils are, in that they only represent a small fraction of the individual organisms that existed not to mention depth of time as in how much happens in a few thousand to a million years,” Poole mentioned.

“In some ways, this has been a paleontological exercise in how much we can know, and how we go about knowing it,” mentioned Marshall, a research coauthor and UC Berkeley professor of integrative biology and of Earth and planetary science, in a press release.

“It’s surprising how much we actually know about these dinosaurs and, from that, how much more we can compute. Our knowledge of T. rex has expanded so greatly in the past few decades thanks to more fossils, more ways of analyzing them and better ways of integrating information over the multiple fossils known,” he mentioned.

Beyond the T. rex

Ibrahim sees different prospects stemming from this research.

“There are a lot of things we don’t know about the physiology, behavior and feeding ecology of Tyrannosaurus, but this study offers an interesting approach to estimating the abundance and preservation rate of dinosaurs, he said.

“I might like to see it utilized to different dinosaurs identified from considerable fossils. Looking at a wider vary of dinosaurs — predators and prey — would possibly allow us to raised evaluate dinosaur-age animal communities to fashionable 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 broadly to the study of dinosaurs.”

NCS’s Kristen Rogers contributed to this story.


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