The study suggests that Tyrannosaurus Rex may have been three different species

A new study suggests that the most famous dinosaur of all time likely corresponded to at least three different species, which were neatly distinguished from each other in terms of anatomy, when they lived and possibly in behaviour.

The hypothesis, proposed by three American researchers, can disentangle the classification of the famous dinosaur rexand create two other species: T. emperor and T. regina.

It is no coincidence that all scientific names are variations of “rex” or “re” in Latin – “regina” means “queen” and “emperor”, of course, “emperador” in the Portuguese ancestral language.

The analysis underlying the “triple personality” From tyrannosaurs It just appeared in the scientific journal Evolutionary Biology. The study was coordinated by independent researcher Gregory Poole and also signed by Scott Pearsons and Jay Van Raalty, of the College of Charleston, South Carolina.

about 12 meters, dinosaur rex It lived between 68 million and 66 million years ago in a wide area of ​​what is now North America. Both the wide geographical distribution and the duration of the animal’s existence open up the possibility of speciation events, that is, the formation of new species of tyrannosaurs from a common ancestor.

Ball and colleagues analyzed this possibility by considering the already known variation in the fossils of T. rex, one of the best-studied species of dinosaur with relatively abundant skeletons. It is known, for example, that there are forms that are more slender (that is, with relatively lighter bones) and other, more powerful forms of the animal. In addition, there are differences in teething.

Some animals have a single tooth called an incisor (by analogy with a mammalian incisor) on each side of the jaw, while others have two incisors.

The scientists’ goal was to assess how these differences compared to the diversity of other dinosaurs, both in relative terms (being larger or smaller than the differences that separate other species) and over time.

This type of analysis will also help in estimating whether T. rex variance can only correspond to normal inter-individual differences (such as between tall and short humans, for example) or whether it can be linked to sexual dimorphism, i.e. differences between males. and female.

Gregory Poole and colleagues worked with 37 specimens classified as T. rex, with which it was possible to analyze the strength of the femurs (femur) of 24 animals. Of these, only 12 had teeth and bones.

One key finding is that the variance in bone strength is up to 30%, which exceeds what you see in related dinosaurs classified together.

Older forms are more robust and tend to have two incisors, while newer forms include both strong and agile animals with only one incisor.

This led researchers to suggest that the oldest strong form, with two incisors, would be called a single T. incisor.

Was there a difference in habits between the trio? For Paul, one possibility is the difference in prey, with the more powerful animals specialized in attacking the powerful herbivores Triceratops, which resembled a rhinoceros shaped like a dinosaur.

“It appears that at the end of the Cretaceous period, the strong T. rex and T. rex. [herbívoros com bico semelhante ao de patos] “We have skeletons, including injuries to the tail, that suggest this possibility,” the researcher said. paper.

For paleontologist Raphael Delcourt, who specializes in the evolution of big dinosaurs Carnivore and postdoctoral researcher at the University of the South Pacific in Ribeirão Preto, the new research brings interesting discussions, but the data presented is still far from sufficient to establish the “triple section” of T. rex.

“You have to look at these samples more carefully and go beyond the strength of the femur and the differences in growth,” he says.

“In any case, the analyzes are important to draw attention to the ecological niche occupied by tyrannosaurs, which may have varied during their evolutionary history and during the development of individuals throughout life, with smaller and smaller animals capturing different prey than adults, for example.”