‘Awesome’ never-before-seen tyrannosaurus may be the ‘missing link’ in T. rex evolution
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Paleontologists have discovered the remains of a never-before-seen tyrannosaurus, which may have been a direct ancestor of the king of the dinosaurs T-Rex. The newly discovered species may help resolve a major debate T. rexthe evolutionary line of.
The newly discovered species, Daspletosaurus wilsoni, has a unique arrangement of spiked horns around its eyes. The tyrannosaurus was identified from parts of a fossilized skull and skeletal fragments, including a rib and a toe bone, which date to about 76.5 million years ago during the Cretaceous period (145 million to 66 million years ago). Paleontologists at the Badlands Dinosaur Museum in North Dakota discovered the fossils in 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 new tab).
The team initially came across the fossils after crew member Jack Wilson spotted a small, flat piece of bone sticking out of the bottom of a rock, which later turned out to be part of dinosaurnostril. Excavating the bones proved extremely challenging, however, as they were buried under 26 feet (8 meters) of solid rock. The researchers had to painstakingly carve out large sections of the rock with impact hammers before they could even begin to excavate the individual bones.
The specimen, designated BDM 107, was playfully named “Sisyphus” in recognition of the enormous effort required to remove the surrounding rock. (Sisyphus is a figure from Greek mythology who, after cheating death twice, was forced by Hades, the god of death, to repeatedly roll a boulder up a mountain for eternity.)
Connected: T. rex and its close relatives were warm-blooded like modern birds
Researchers believe that D. Wilson was a descendant of Daspletosaurus torosus and the predecessor of Daspletosaurus horneri, which probably appeared between 77 and 75 million years ago. The anatomy of the newly discovered beast supports the idea that Daspletosaurus lineage is the progenitor of the mighty T. rex. All three species of daspletosaurs belong to the Tyrannosauridae family, which includes nine genera, including Tyrannosaurus. (The genus Daspletosaurus is Greek for “terrible lizard”.)
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Until now, the lineage of Tyrannosauridae has been elusive, making it difficult to pinpoint the exact one evolutionary relationships between individual species.
“Many researchers disagree whether tyrannosaurids represent a single lineage that evolved locally or several closely related species that did not derive from each other,” write study co-authors and paleontologists Elias Warshaw and Denver Fowler statement (opens in new tab). This is not helped by the lack of high-quality study samples, they added.
But the discovery of D. Wilson suggests that the three Daspletosaurs came one after the other, as “successive ladder-like steps in an evolutionary line,” rather than branching off from each other as “evolutionary cousins,” the researchers wrote.
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D. Wilson is a good candidate for a transitional species between D. torosus and D. horneri as it shares a number of traits with more ancient 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 statement.
“Thus, D. Wilson is a ‘halfway point’ or ‘missing link’ between older and younger tyrannosaur species,” the researchers wrote.
Given that these species could have evolved one after the other, the team hypothesizes that the remaining tyrannosaurids, incl. T. rex, can also appear in a similar linear fashion. The researchers are currently planning a new study to investigate this idea, according to the statement.
