Scientists suggest that 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 included three species and not the only tyrannosaurus, based on the disparity of femurs and teeth among dozens. from its fossils.

T. rex, meaning “tyrant lizard king,” has been the only species of the genus Tyrannosaurus that has been recognized since the dinosaur was first described in 1905. The genus is a broader group of related organisms than species.

A team of three researchers led by independent paleontologist and palaeontologist Gregory Ball said Monday that the differences they spotted in examining about thirty tyrannosaurus fossils warrant the identification of two additional species: T. and T. Regina, meaning “tyrant lizard queen”.

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

Tyrannosaurus roamed western North America during the Cretaceous period in the twilight of the age of the dinosaurs before an asteroid hit Mexico’s Yucatan Peninsula 66 million years ago, wiping out the dinosaurs.

Ball and colleagues note differences in the toughness of the femur or femur — some larger, others lightly built — and differences in the number of small teeth at the tip of the lower jaw between the fossils examined.

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“It’s a matter of concern that this would be controversial because of the attractive stature of T. rex, but on the other hand, the study wouldn’t get that much attention otherwise,” said Ball, whose study was published in the journal. evolutionary biology.

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

“Ultimately, to me, this difference is very slight and does not indicate a meaningful biological separation of distinct species that can be identified based on clear, explicit and consistent differences,” said University of Edinburgh paleontologist Steve Brusatte.

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

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

Tyrannosaurus had a massive head and tremendous bite force, walked on strong legs, and had only two fingers weak arms. Perhaps the largest known dinosaur was a specimen called Sue in Chicago’s Field Museum, measuring 40-1/2 feet (12.3 meters) in length and an estimated length of 9 tons. The new study concludes that Sue is not a T. rex but rather a T.

The scale of the differences between the three proposed tyrannosaurus 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 are members of the same genus as Panther, but they have enough differences that they are recognized as separate species.

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

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

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Reporting by Will Dunham; Editing by Rosalba O’Brien

Our criteria: Thomson Reuters Trust Principles.

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