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Paleontologists have discovered the remains of a never-before-seen tyrannosaurus that may have been a direct ancestor of the dinosaur king tyrannosaurus rex. The new species could help settle a big debate about T. rexof the evolutionary line.
new species, Daspletosaurus wilsoni, has a unique arrangement of spiked hornets around its eyes. Tyrannosaurus was identified from parts of a fossilized skull and skeletal fragments, including a rib and toe bone, which date to around 76.5 million years ago during the Cretaceous period (145 to 66 million years ago). Paleontologists from the Badlands Dinosaur Museum in North Dakota discovered the fossils from the Judith River Formation in northeastern Montana between 2017 and 2021, according to a new study published Nov. 25 in the journal Paleontology and evolutionary science (opens in a new tab).
The team first stumbled upon the fossils after crew member Jack Wilson noticed a small piece of flat bone protruding from the bottom of a cliff, which later turned out to be part of the dinosauris the nostril. Excavating the bones, however, proved extremely difficult as they were buried under 26 feet (8 meters) of solid rock. Researchers had to carefully chisel large sections of the cliff with jackhammers before they could even begin digging out the individual bones.
The specimen, designated BDM 107, was playfully nicknamed “Sisyphus” in recognition of the enormous effort required to remove the surrounding rock. (Sisyphus is a figure in Greek mythology who, after cheating death twice, was forced by Hades, the god of death, to repeatedly roll a rock down a mountain for eternity.)
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Researchers think that D.wilson was the descendant of Daspletosaurus torosus and the predecessor of Daspletosaurus horneri, which probably emerged between 77 and 75 million years ago. The anatomy of the found beast supports the idea that the Daspletosaurus the lineage is ancestral to the powerful T. rex. The three species of daspletosaurs belong to the family Tyrannosauridae, which comprises nine genera, including Tyrannosaurus. (Genre Daspletosaurus is Greek for “creepy lizard”.)
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Until now, the Tyrannosauridae lineage has been difficult to disentangle, making it difficult to determine exactly evolutionary relationships between individual species.
“Many researchers disagree on whether tyrannosaurids represent a single lineage evolving in place, or several closely related species not descended from each other,” wrote co-authors and paleontologist Elías Warshaw and Denver Fowler in an article. statement (opens in a new tab). This was not helped by the lack of high-quality specimens to examine, they added.
But the discovery of D.wilson suggests that the three daspletosaurs came one after another, as “consecutive ladder-like steps in a single evolutionary lineage”, rather than separating from each other as “evolutionary cousins”, wrote Researchers.
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D.wilson is a good candidate to be a species of transition between D. torosus and D. horneri because it shares a number of traits with older tyrannosaurs, such as having a prominent set of horns around the eye, as well as traits seen in younger species, such as enlarged air pockets in the skull , according to the press release.
“In this way, D.wilson is an ‘intermediate point’ or ‘missing link’ between older and younger tyrannosaur species,” the researchers wrote.
Since these species could have evolved one after another, the team suggests that the rest of the tyrannosaurids, including T. rex, could also have emerged in a similar linear fashion. The researchers are currently planning a new study to explore this idea, according to the statement.
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