A fossil discovered in 2017 in Montana by a team of researchers would actually be a new species of tyrannosaurus according to a study published on November 25 in the specialized journal PeerJ. This discovery would thus make it possible to make links between several species of tyrannosaurus, in particular with the famous T-Rex.
Contrary to what one might think, the T-Rex is not the only specimen of tyrannosaurus who existed. And it is not a discovery of 2017 that will say the opposite. Indeed, that year, a team of American paleontologists unearthed a small piece of bone in Montana (United States), which turned out to be the middle part of a nostril of a tyrannosaur. Of the excavations Subsequently carried out in 2020 and 2021 uncovered a skull and part of the skeleton which would date from around 76.5 million years ago, belonging to the Cretaceous period. According to a study published on 25 November in the specialist journal PeerJit is a species belonging to a line of tyrannosaurids – a family of dinosaurs – of the genus Daspletosaurus, which scientists have named Daspletosaurus wilsoni.
An Ancestor of the T-Rex?
According to the researchers, this species was the descendant of Daspletosaurus torosus and the predecessor of Daspletosaurus horneri, which probably emerged between 77 and 75 million years ago, relays Live Science magazine. By studying the anatomy of this new species, the researchers confirmed the idea that the Daspletosaurus lineage would be the ancestors of the famous Tyrannosaurus Rex, more commonly known as T.Rex. “The three species of daspletosaurus belong to the family Tyrannosauridae, which comprises nine genera, including Tyrannosaurus,” explains Live Science.
A fuzzy genealogy
Until this new discovery, the Tyrannosauridae lineage remained difficult to disentangle, which made it difficult “to determine the exact evolutionary relationships between the different species”, relays Live Science. “Many researchers disagree on whether tyrannosaurids represent a single lineage evolving in place, or several closely related species that are not descended from each other,” write the study co-authors.
But precisely, the many specific traits that Daspletosaurus wilsoni shares with older tyrannosaurs, suggest that it “could be a good candidate to be a species of transition between D. torosus and D. horneri”. The three species would then have arrived one after the other as “consecutive ladder-like steps in a single evolutionary lineage”, rather than branching off from each other as “evolutionary cousins” explain the researchers in their study.
Daspletosaurus wilsoni would therefore be a “halfway point” or a “missing link” between older and younger tyrannosaur species.
If these species evolved one after another, the scientists suggest that the rest of the tyrannosaurids, including T. rex, “may also have emerged in a similar linear fashion.” Research continues to try to confirm this idea.
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