by Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on exciting discoveries, scientific advances and more.
A previously unknown relative of the most iconic dinosaur, Tyrannosaurus rex, has been newly identified, according to a study published Thursday. The revelation offers a new clue that could help paleontologists solve another step in the evolutionary chain that ended with the giant predatory tyrannosaur, T. rex.
Known as Tyrannosaurus mcraeensis, the creature probably roamed the Earth up to 7 million years before T. rex evolved. The bones were dated to between 72 million and 73 million years old during the late Campanian Maastrichtian Period.
But the bones of Tyrannosaurus mcraeensis were discovered decades before the creature officially received its scientific name. About one quarter of his fossilized skull was found during the 1980s and early 90s in what is now Elephant Butte, New Mexico. Because of the size of the specimens, the New Mexico Museum of Natural History & Science originally categorized the bones as T. rex, which grew up to 39 feet (12 meters) long and weighed 10 tons.
T. rex vs its relative
There were two major differences between T. rex and T. mcraeensis.
“The lower jaw in Tyrannosaurus rex is quite strong. Our jaw is obviously large and toothy, but it’s narrower than what we usually see in Tyrannosaurus rex,” said Anthony R. Fiorillo, co-author of the study published Thursday in the journal Scientific Reports. T. rex’s strong jaw meant it could “do whatever it wanted. A narrower jaw means, even with the big teeth, he would have less bite force.”
The other major difference was that, unlike T. rex, T. mcraeensis did not have a prominent ridge over its eyes. Scientists believe T. rex’s ridge was used to help attract others, like antlers on deer or elk, said Fiorillo, who is executive director of the New Mexico Museum of Natural History and Science in Albuquerque. In T. mcraeensis, the ridge is much more relaxed.
Why go big?
Giant tyrannosaurs probably evolved as an evolutionary adaptation to the availability of large herbivores, the authors wrote. However, according to the study, why giant plant-eating dinosaurs evolved is still a mystery.
Fiorillo emphasized that this is currently a “highly speculative” idea, but added that, unlike the picky tyrannosaur found in the Arctic — called Nanuqsaurus hoglundi — there probably weren’t large changes in temperature and light in the American south. North due to T. mcraeensis. it was able to continue to grow. Arctic conditions may have played a role in the very small size of N. hoglundi, but other tyrannosaurids from the same period were generally much smaller than T. mcraeensis.
The research team will now return to the rock formation where the specimen was found to see if they can find more bones.
“Then, because it’s so big, we have to change some of our investigation to try to understand the paleontology and the environment that this animal lived in so that we can begin to understand what about New Mexico was so special this animal’s adaptation. that life was going to get bigger,” Fiorillo said.
Tyrannosaurus slot
When the lower jaw was first found, there weren’t many T. rex specimens out there, Fiorillo said.
The identity of T. mcraeensis was revealed decades later thanks to Sebastian G. Dalman, first author of the study who is an associate researcher at the museum as well as a paleontology consultant to the Springfield Science Museum in Massachusetts.
While studying the bones starting in 2013, Dalman was the first to suggest that they might be “something different,” Fiorillo said.
As the largest apex predator of its time, T. rex has had considerable attention from the paleontological community, both professional and amateur, for many years. According to Fiorillo, the ferocious giant’s interest and huge roles in popular movies such as “King Kong” and “Jurassic Park” have attracted the interest of scientists and amateur fossil hunters alike.
“And that improved our sample size,” he said. “That set the table for when Sebastian started looking at our specimen and saying, ‘Hey, these are not the same as the famous Tyrannosaurus rex specimens from places like Montana.'”
For more CNN news and newsletters create an account at CNN.com
