Even though we have a lot of knowledge about the T. rex that existed millions of years ago, scientists are still puzzled as to how the renowned predator came to be. It's possible that researchers have uncovered the final piece with a recent finding.
T. Rex roaring on a deserted land. (Credit: DM7/Shutterstock)
The Tyrannosaurus Rex is probably the most well-known dinosaur to date. This mega-beast had teeth as long as your forearm, a bite force to match, and was also the biggest predator in its habitat. For at least 2 million years, it could consume prey as large as a school bus. It was still standing when an asteroid ravaged the earth at the end of the dinosaur era. Even still, despite how much we do know about T. rex, we know comparatively little about its evolutionary background.
Daspletosaurus, a rare species of theropod discovered in Montana, is thought to have later developed into T. rex, according to researchers. And in a further investigation that was revealed in a PeerJ article from November 2022, scientists discovered a third Daspletosaurus species called Daspletosaurus wilsoni that, in addition to the two previous known species, may aid in bridging the gap.
D. wilsoni, which lived 76 million years ago, "displays a unique combination of ancestral and derived characteristics" that indicate it was an intermediate species before T. rex.
"We named a species that fits into the genus Daspletosaurus that forms a halfway point between the two other species (D. torosus and D. horneri)," explains Elas Warshaw, study author and research associate at the Badlands Dinosaur Museum in Dickinson, North Dakota.
Looking Back at T. Rex
D. wilsoni, like T. rex, would have been the biggest predator in the region, feasting on enormous herbivores with horns and duck bills like Brachylophosaurus and Centrosaurus. The planet would have also seemed differently than it does today.
According to Warshaw, the Western Interior Sea, a swallow-sized inland sea, spanned much of North America and Montana 76 million years ago. When the dinosaur was alive, the region where the scientists discovered D. wilsoni would have been coastal. He says, "I would liken it to a modern Louisiana with dinosaurs."
According to researchers, D. wilsoni was a precursor of T. rex, which emerged 10 million years later and evolved into a larger dinosaur with slenderer horns. This study and a significant portion of Warshaw's research demonstrate that Daspletosaurus did not become extinct but instead developed into T. rex.
However, Warshaw notes that there is still much we do not know due to a lack of research. The oldest T. rex and the final Daspletosaurus are separated by several million years.
Mind the Gap of Evolution
While we're still not there, Scott Persons, head curator of the Mace Brown Museum of Natural History in Charleston, South Carolina, who was not involved in the study, argues that we are moving in the right direction. This study demonstrates a crucial connection.
According to Persons, "the interesting thing about this study is that they have this new definable species of Daspletosaurus that falls right in the middle of the two previously known species - both because it appears at a middle point in time and in terms of its evolutionary relationships." The species possesses a mix of recent and historical characteristics that further demonstrate its ambiguous status.
Additionally, this finding is significantly more important to Warshaw and the Badlands Dinosaur Museum team than simply identifying a new species since it demonstrates how dinosaurs evolved. Anagenesis is a theory that suggests one species developed into another.
The research team is demonstrating that many dinosaurs did not become extinct before the Chicxulub crater 66 million years ago; rather, "their replacements are descendants that evolved into one another," according to Warshaw. This would apply to a lot more animals than only the most well-known mega-predator in the planet.
