Last February, a shockwave swept through paleontology: researchers detected in the fossils of the T. rex three different animal species instead of one. They also immediately suggested new names. They baptized an older species Tyrannosaurus Imperator: the emperor. This was followed by a heavily built variant, T. rex (king), and a slimmer one, T. regina (queen). Time to adjust museum signs worldwide?
Not so quickly, other paleontologists responded immediately. In Evolutionary Biology, the same journal that published the original study, some of them now refute the arguments at length. They make it clear that much is still unclear about even the most famous dinosaurs: studying animals from tens of millions of years ago on the basis of little more than dry bones is not easy.
thighs
That there would have been three types is based in large part on differences in the thickness of the femurs and the ratio between the width of the second and third teeth. But according to the new research, these differences aren’t clear enough to speak of multiple species.
For example, they analyzed the bones of more than a hundred species of birds to see whether the variation in the dinosaurs’ thigh bones is really that remarkable. Within some bird species, this variation was found to be three times greater than that of T. rex. Also, teeth in the dinosaur jaws were broken or missing in several cases, which can distort the measurements.
The researchers further point out that some specimens cannot be counted as one of the new proposed species because they have properties of several at the same time. In addition, fossils of less than 40 individuals have been analysed, which, given the subtle differences, is too few to speak of multiple species, they write.
Other species
Charles Marshall, a paleontologist at the University of California and not involved in either study, believes that the bottom of the three-species thesis has been completely eroded. He believes that clearer differences between the skeletons must first be demonstrated.
Philip Currie, a paleontologist at the University of Albert in Canada, also finds the counterarguments convincing. However, it still gnaws that one T. rex was clearly built differently than the other, he emails. However, there are also other possible explanations for this, such as differences between males and females, or subspecies that lived in other places. “I’m not sure we could ever prove there was more than one species.”
A finding of several related T. rexes together, buried at the same time by a landslide, for example, could provide the answer. “It’s not impossible, because we’ve already found places where other tyrannosaurs (Albertosaurus, Daspletosaurus, Tarbosaurus) have died en masse,” Currie said. What he thinks is needed anyway: more bones and more research. “I don’t see this debate ending anytime soon.”
Most Advanced Carnivores
And to think this is far from the only discussion raging around the T. rex. After all, were they the formidable hunters from the movies, or did they mainly eat carrion in reality? And did they live alone, or did they sometimes travel in groups? ‘T. rex is not only the most famous dinosaur, but also one of the most advanced carnivores to ever terrorize the land,” said Currie. “That’s why we remain fascinated by this animal and continue to research it.”