Scientists want to divide Tyrannosaurus rex into three species. not everyone is happy
“Ultimately, to me, this variation is very minor and does not indicate a meaningful biological separation of distinct species that can be defined on the basis of clear, explicit, and consistent differences,” said the paleontologist from the University of Edinburgh, Steve Brusatte.
“It is difficult to define a species, even for animals today, and these fossils have no genetic evidence that can test whether there were really separate populations. Until I see much more evidence solid, they’re still T. rexes to me, and that’s what I’ll call them,” Brusatte added.
Paul did not rule out that differences between individuals or differences between males and females of Tyrannosaurus were at play, but called it unlikely.
Tyrannosaurus had a massive head and enormous bite force, walked on two strong legs, and had puny arms with only two fingers. Perhaps the largest known tyrannosaur is a specimen named Sue at the Field Museum in Chicago, measuring 12.3 meters long and weighing around 8 tons. The new study concluded that Sue is not a T. rex but rather a T. imperator.
The magnitude of the differences between the three proposed Tyrannosaurus species, Paul said, is akin 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, Panthera, but have enough differences to be recognized as separate species.
Paleontologist Thomas Carr of Carthage College in Wisconsin, whose variation study 2020 in T. rex found no evidence of multiple species, also differed with the new study.
“Perhaps most damning is the fact that the authors were unable to refer several excellent skulls to one of the three species,” Carr said. “If their species are valid, then more than two characteristics should identify them: almost every detail – especially in the head – should be different.”