Known as one of the greatest predators in history, the Tyrannosaurus rex was a prehistoric dinosaur that lived 65 million years ago. The dinosaur lived for around one and a half million years, according to paleontologist Luis Alcalá, who also serves as the director of the Granada Science Park. And it is perhaps one of the most well-known extinct animals in the world. Numerous investigations have been conducted in this regard, including the identification of new relatives and the finding of the pace at which it walked, which was comparable to that of humans. He has acted in and starred in a slew of blockbusters, including Jurassic Park, and his name has even been given to a musical group in honor of his achievements. The Tyrannosaurus rex was thought to be the only species in the genus Tyrannosaurus until recently. However, an analysis published last Tuesday in the journal Evolutionary Biology raises the idea that the remains discovered of these animals actually serve three separate species rather of just one, as previously thought. Tyrannosaurus imperator and Tyrannosaurus regina are probable new species names proposed by the writers, who have even given them scientific names. This classification is the result of an examination of the physical distinctions in the femur, other bones, and dental structures among the individuals who were discovered in the study.

A total of 38 specimens' bone and dental remains were studied in this study. Twenty-four of them were used to compare femur robustness, which was measured by measuring the length and circumference of the bone, which allowed them to determine the strength of the bone. The femurs showed a great deal of variation, with some being robust and others being graceful. In several circumstances, the difference in robustness was really large, and they discovered that some were even twice as robust as graceful in some cases. As a result, they ruled out the possibility that the difference was due to gender. The researchers also believe it is not tied to growth because strong femurs were detected in juvenile specimens and some gracile ones in mature specimens, indicating that it is not related to growth. The researchers also checked for one or two slender incisor teeth on either side of the front ends of the jaws by measuring the diameter of the base of each tooth or the space between each tooth's gums and comparing the results. Single incisor teeth are associated with increased gracefulness in those who possess them. Only 12 of the total number of fossils evaluated possessed femur measurements and dental remnants, according to the researchers.

A fundamental aspect, according to paleontologist and professor emeritus at the Autonomous University of Madrid José Luis Sanz, is the number of individuals analyzed: "This number is insufficient to be statistically significant," he says. "There are other factors that must be taken into consideration." Until we have a larger number of specimens, I would not be bold enough to assign a name to them or declare that they are separate species." Alcalá, on the other hand, believes that they were appointed too soon and argues that, while they may be correct, the evidence they have provided to support their position is "extremely weak."

Tyrannosaurus imperator bones discovered in the lower and middle strata of the soil have been linked to the dinosaur. They are distinguished by their more powerful femurs and the presence of two front teeth in most cases. Possibly, as they argue, this is owing to the fact that they have retained it from their forefathers and foremothers. Tyrannosaurus regina, on the other hand, is associated with fossils found in the top and maybe middle layers of the sediment, and has thinner and hence more gracile femurs, as well as a single incisor tooth, suggesting that it lived in the upper and possibly middle layers of the sediment. Tyrannosaurus rex specimens with more robust femurs and one incisor tooth were found in the higher layer and potentially in the center of the silt, confirming the existence of the previously known Tyrannosaurus rex. As one of the investigation's authors, Gregory Paul, an independent researcher and illustrator who has worked to establish the appearance of Mesozoic creatures in documentaries and films such as Jurassic Park and who has contributed to the discovery of the species, claims that only a quarter of the specimens found correspond to this species.

The research, according to him, began as a result of a discussion given by John Scannella, a member of the Vertebrate Paleontology Society, in which he discussed triceratops, which was one of the Tyrannosaurus's prey. At the time, it was being debated whether or not this predator, like these, would have evolved into a new species. A second reason for his interest in this dinosaur was to instigate a taxonomic investigation into it because he believed that a kind of "garbage" was being created as a result of the specimens being thrown into Tyrannosaurus rex without first undergoing an anatomical and stratigraphic examination of them. As Paul contends, the fossils discovered demonstrate that T. rexit was not a single species that remained the same throughout its existence, but rather a group of species that evolved in line with Darwinian theory. 66 million years ago, the Cretaceous period came to an end, and these animals were living at the time.

Despite the fact that they do not rule out that the observed variation is due to abnormal sexual dimorphism or extreme individual variations, the authors suggest that the diversity in resilience is significantly greater than that observed in giant dinosaur species. A table with points in support of and against the investigation, Sanz notes, is "greatly appreciated" at the conclusion of the investigation, which he describes as "quite thoughtful." According to him, the only difficulty is that some of the difficulties, such as the tiny sample size, are "one of the most serious," as the researchers themselves acknowledge.