Scientists defend T. rex as only species of mighty Tyrannosaurus

By Will Dunham

WASHINGTON (Reuters) – T. rex nonetheless reigns because the king of dinosaurs, in keeping with scientists who on Monday argued towards a contentious speculation superior this yr that the mighty meat-eater Tyrannosaurus must be acknowledged as three species and never only one.

Seven paleontologists in analysis https://hyperlink.springer.com/article/10.1007/s11692-022-09573-1 printed on Monday mentioned a research from March provided inadequate proof to point out that there have been three Tyrannosaurus species primarily based on fossils of the world’s most-famous dinosaur, citing improper statistical strategies, restricted comparative samples and defective measurements.

T. rex has been the only species of the genus Tyrannosaurus acknowledged for the reason that dinosaur was first described in 1905. A genus is a broader grouping of associated organisms than a species.

Three different researchers mentioned within the earlier research https://hyperlink.springer.com/article/10.1007/s11692-022-09561-5 printed in the identical journal that three species must be acknowledged primarily based on variation within the thickness of thighbones and within the form of the decrease entrance tooth amongst about three dozen Tyrannosaurus specimens.

“The proof must be convincing, and to abruptly divide such an iconic animal like T. rex, which has been recognized for over 100 years, into totally different species requires a excessive burden of proof. It’s true that there’s variation within the dimension and form of T. rex bones, however in our new research we present that this variation is minimal,” mentioned College of Edinburgh paleontologist Steve Brusatte, a co-author of the brand new research printed within the journal Evolutionary Biology.

Tyrannosaurus, a part of a bunch known as theropods that included all of the carnivorous dinosaurs, had a large head and large chunk energy, walked on two robust legs, and had puny arms with simply two fingers.

The brand new research checked out intra-species variation in thighbone thickness in 4 different meat-eating dinosaurs and 112 species of dwelling birds, descendants of small feathered theropods, discovering that Tyrannosaurus variations had been unexceptional.

“It’s regular for any species to be variable in dimension and form. Simply take a look at the vary of top and waistlines and toothy grins in individuals at this time, all of whom are members of a single species. So the variations between the bones and tooth of T. rex are so minor that they don’t help the division of T. rex into a number of species,” Brusatte mentioned.

Tyrannosaurus roamed western North America throughout the Cretaceous Interval on the twilight of the dinosaur age earlier than an asteroid struck Mexico’s Yucatan Peninsula 66 million years in the past, dooming the dinosaurs.

“Tyrannosaurus rex stays the one true king of the dinosaurs. It’s the solely species of big apex predator dinosaur that lived on the finish of the Cretaceous in North America,” Brusatte added.

Along with the species T. rex, that means “tyrant lizard king,” Baltimore-based unbiased paleontologist and paleoartist Gregory Paul and two colleagues proposed two extra species: T. imperator, that means “tyrant lizard emperor,” and T. regina, that means “tyrant lizard queen.”

Paul criticized the brand new work as unexpectedly achieved and “not a correct scientific research.”

“It comes throughout as paleopropaganda that seems to be structured to defend T. rex, quite than significantly discover the probabilities that fossil specimens of the genus Tyrannosaurus contained the multiple species that the genus actually did,” Paul mentioned.

“There’s something about beloved T. rex that causes individuals to turn out to be agitated to a level not seen with different paleotaxa (historic organisms). Had our paper been in regards to the species of, say, the additionally gigantic Argentinian theropod Giganotosaurus there very probably wouldn’t have been a lot fuss and hassle,” Paul added.

Maybe the largest-known Tyrannosaurus is a specimen named Sue on the Discipline Museum in Chicago, at 40-1/2 ft (12.3 meters) lengthy.

“We’re open-minded that there could also be a number of species of Tyrannosaurus,” Brusatte mentioned. “We simply want extra and higher fossils. The variety of fossils of their dataset is so small that it is laborious to search out any constant technique to divide Tyrannosaurus into a number of species primarily based on clear, easy-to-define, constant variations.”

(Reporting by Will Dunham; Modifying by Lisa Shumaker)