T.rex gains closest relative: Tyrannosaurus mcraeensis – 01/15/2024 – Science

The carnivorous giant Tyrannosaurus rex has just gained an older “cousin”: Tyrannosaurus mcraeensiswhich inhabited Earth between 5 million and 7 million years earlier than its famous relative.

The description of the new species was based on the analysis of a partially complete skull, which had been stored at the New Mexico Museum of Natural History and Science, in the United States, for more than 30 years.

The fossilized remains were initially classified as being from a T.rex, but when analyzing the sample again, a group of paleontologists realized that something was different. Upon studying the specimen in detail, they concluded that it was a new species.

According to scientists, although the dimensions are very similar, the Tyrannosaurus mcraeensis There are several subtle differences in the shape and junction of the skull bones.

Even though pop culture has transformed the Tyrannosaurus rex in one of the most famous dinosaurs in the world, knowledge about the animal’s evolution still has several gaps.

Closest relative yet identified T.rexthe new species could help to better understand the past and evolution of tyrannosaurs.

“I think the big surprise [com a nova espécie] was seeing that these giant tyrannosaurs grew much earlier in time than we thought,” he told Sheet Nick Longrich, researcher at Barth University, in the United Kingdom, and one of the authors of the work, published in the journal Scientific Reports.

The paleontologist explains that the T.rex it was “an enormous animal, very specialized and quite unlike anything that had been seen before in North America.”

Due to the high complexity of the species, the fact that there are few details about the evolutionary path of this giant, which emerged around 67 million years ago, still intrigues scientists.

“It was clear that we were missing a huge part of their story,” says Longrich. “Or rather, we thought we were losing, since the bones [que levaram à descoberta da nova espécie] they were already in a museum, waiting to be identified.”

In recent years, studies into the past of these colossi have generated controversy. In 2022, a controversial article published in the specialized journal Evolutionary Biology proposed dividing the Tyrannosaurus rex in three distinct species of tyrannosaurs: the T.rex (with modifications), the T.regina (queen) and the T. imperator (emperor).

The separation proposal, which would be based on differences in the bones of their legs and teeth, generated heated expressions of opposition in academia, including questioning the taxonomy analysis capabilities of the work and its authors.

Although the article describing the T. mcraeensis is much more robust, some paleontologists are calling for more studies before the hammer is dropped on the new species.

“I hesitate to consider the Tyrannosaurus mcraeensis distinct from Tyrannosaurus rex“, said Jared Voris, from the University of Calgary, Canada, in an interview with New Scientist magazine. The paleontologist considers that many of the anatomical characteristics that supposedly make the new species unique can also be found in specimens of T.rex.

Regardless of the species issue, the date and location attributed to the specimen studied, says Voris, should bring new perspectives to the study of the evolution and geographic dispersion of animals.

There are some hypotheses for where tyrannosaurs appeared. Therefore, the location of the skull’s discovery may provide clues about these origins. The material was found during an excavation in the Hall Lakem Formation in the state of New Mexico, in the southern United States.

“It seems to imply that giant tyrannosaurs evolved to the South, which is curious, because that’s also where we see giant duck-billed dinosaurs, giant horned dinosaurs and huge sauropods. [herbívoros com pescoço longo]”, says Nick Longrich, co-author of the article.

According to him, there are indications of a certain division, with more larger dinosaurs in the South of Laramidia, an island continent that divided the region that is today North America.

“In the Arctic, in Alaska, dinosaurs are relatively small in comparison. Therefore, there seem to be geographic patterns in the gigantism of dinosaurs: with large ones in the South and smaller dinosaurs in the North”, he detailed.

Despite the existing evidence, the researcher says that more studies are still needed to confirm this evidence. “We need to look at this much more closely to know for sure,” he added.