Scientists Suggest Tyrannosaurus Had Three Species, Not Just ‘Rex’

WASHINGTON (Reuters) – A group of researchers has suggested that dinosaurs, the most famous dinosaur and apex predator, actually comprised three species rather than just one tyrannosaur, based on the disparity of femurs and teeth among dozens . of their fossils.

T. rex, which means “tyrant lizard king”, is the only recognized species of the genus Tyrannosaurus since the dinosaur was first described in 1905. The genus is a larger group of related organisms than species.

A team of three researchers led by paleontologist and independent paleontologist Gregory Ball said on Monday that the differences detected when examining about 30 tyrannosaur fossils justify the identification of two additional species: T. and T. regina, which means “tyrant lizard queen”.

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“After more than a century of putting all specimens into a species without carefully examining the problem, the first and only analysis found that tyrannosaur variation exceeded dinosaur standards and was distributed over time in a way that suggested that Darwinian speciation had taken place from (one species) into two new species before leading to the eventual extinction of the dinosaurs halted evolution,” Paul said.

Tyrannosaurus roamed western North America during the Cretaceous Period, at the twilight of the Age of Dinosaurs, before an asteroid struck Mexico’s Yucatan Peninsula 66 million years ago, wiping out dinosaurs.

Ball and his colleagues note differences in the hardness of the femur or femur – some larger, others lightly built – and differences in the number of small teeth at the end of the lower jaw between the fossils examined.

“It’s concerning that this is controversial because of the attractive stature of T. rex, but on the other hand, the study wouldn’t get as much attention otherwise,” said Ball, whose study was published in the newspaper. evolutionary biology.

Paul was right about the controversy. Some paleontologists who were not part of the study disagreed with its conclusions.

“Ultimately, for me, this difference is very small and does not indicate a significant biological separation of distinct species that can be identified on the basis of clear, explicit and consistent differences,” said the paleontologist of the University of Edinburgh Steve Brusatte.

“It’s hard to identify a species, even for animals today, and these fossils don’t have genetic evidence that can test whether separate groups really exist. Until I see much stronger evidence, they’re still all T. rex to me,” Brusatte added, “I’ll call them.”

Ball did not rule out differences between individuals or differences between male and female tyrannosaurs playing a role, but he described this as unlikely.

Tyrannosaurus had a huge head and enormous bite force, walked on strong legs and had only two fingers on its weak arms. Perhaps the largest known dinosaur was a specimen named Sue at the Field Museum in Chicago, measuring 12.3 meters in length and an estimated length of 9 tons. The new study concludes that Sue is not a T. rex, but a T.

The magnitude of the differences between the three proposed tyrannosaur species, Ball said, is similar to the differences between a lion — scientific name Panthera leo — and a tiger, scientific name Panthera tigris. Lions and tigers belong to the same genus as Panther, but they have enough differences to be recognized as separate species.

Paleontologist Thomas Carr of Carthage College, Wisconsin, awarded in 2020 study difference In T. rex, he found no evidence of multiple species and also disagreed with the new study.

“Perhaps most compelling is the fact that the authors were unable to assign many excellent skulls to any of the three species,” Carr said. “If your types are valid, they must specify more than two attributes: almost every detail – especially in the header – must be different.”

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Reporting by Will Dunham; Edited by Rosalba O’Brien

Our criteria: Thomson Reuters Trust Principles.

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