When watching movies like Jurassic Park, Night at the Museum, or other movies involving dinosaurs, one dinosaur that’s always included is the famous T-Rex. Hearing the name means that we can easily picture the large head and body with tiny arms. However, new studies show that there is more to the creature than we previously knew.
In a controversial study published in Evolutionary Biology, based on deeper examinations of related specimens, researchers are proposing that the T-Rex was one of three species: T. Rex, T. Regina, and T. Imperator. Researchers took samples of 37 specimens into closer examination, noting variations in femur, the bone of the thigh or upper hind limb, size and dentistry, along with the layers in which dinosaurs are found, and discovered that these three species are found in lower layers.

However, this research alone isn’t enough to convince all paleontologists.

Steve Brusatte of the University of Edinburgh disagrees with the newfound discoveries, telling the Guardian, “I understand the temptation to divide T. Rex into different species, because there is some variation in the fossil bones that we have, but ultimately, to me, this variation is very minor and not indicative of meaningful biological separation of distinct species that can be defined based on clear, explicit, consistent differences.”

A paleontologist at Carthage College in Kenosha, Thomas Carr, disagrees with the new claim as well, given that he previously studied variations in 1,850 different features in T. Rex specimens and found no evidence claiming that the species should be divided. He believes that the new research only provides subtle differences that shouldn’t conclude the division of the species, but only shows minor differences in the individual creatures. “It’s just shades of gray and shapes in the clouds,” Carr analogizes to Michael Greshko of National Geographic.

The definition of a species and how it applies to each individual creature has been debated between paleontologists, the actual definition being a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. It has been claimed by the study’s author that due to lack of research, the T. Rex is the only species in the genus, defined as a principal taxonomic category that ranks above species and below family, of the Tyrannosaurus.
However, considering its over 2 million years of existence, it is entirely possible that the T. Rex branched into different species. Paul Sereno, a paleontologist of the University of Chicago, agrees with this statement.

For years, we’ve believed the T. Rex, translating to the tyrant lizard king, to be the single dinosaur that reigned the prehistoric world. Are people today ready to accept a huge new discovery that could alter this current belief?
“It’s difficult to believe that one species could [have lasted] millions of years across that expansive territory, with the amazing amount of herbivores that were out there to be eaten,” says Sereno.