When fossil hunters unearthed the remains of a dinosaur in the hills of eastern Montana five years ago, they brought with them several key features of a Tyrannosaurus rex: a pair of giant legs for walking, a pair of much smaller arms for tearing apart prey and a long tail stretching behind it.
But unlike an adult T. rex, which would be the size of a city bus, this dinosaur was more the size of a pickup truck.
The specimen, now on sale for $20 million in a London art gallery, raises a question that has come to obsess paleontologists: Is it simply a young T. rex that died before reaching maturity, or does it represent a different model but related species of dinosaur known as Nanotyrannus?
The dispute has produced reams of scientific research and decades of debate, polarizing paleontologists along the way. Now, with dinosaur fossils increasingly fetching eye-popping prices at auctions, the once-esoteric dispute has begun to ripple through auction houses and galleries, where some see the T. rex name as a valuable trademark which can more easily obtain high prices.
“It’s ultimately a pretty trivial question about the taxonomy and classification of a very particular type of dinosaur,” said Steve Brusatte, a paleontologist at the University of Edinburgh. “However, this is T. rex, and the debate always gets a little more fierce when the king of the dinosaurs is involved.”
On the Internet, juvenile T. rex vs. Nanotyrannus have become something of a meme, providing fuel for jokes on niche social media channels. (“I won’t believe in Nanotyrannus until he shows up at my door and eats me,” a paleontology student with the nickname “TheDinoBuff” joked recently on the social media site X.)
The gallery selling the specimen discovered in Montana, known as Chomper, faced a choice. Call it a juvenile T. rex? Label it as Nanotyrannus? Or embrace the ambiguity of an unresolved scientific debate?
The David Aaron gallery in London called it a “rare juvenile Tyrannosaurus rex skeleton”. He cited an influential 2020 paper on the topic led by Holly N. Woodward, who used an analysis of growth rings within bone samples from two disputed specimens – estimated to be similar in size to Chomper – to argue who were young people growing up. splash.
Salomon Aaron, the gallery’s director, said paleontologists had recommended classifying the skeleton as a juvenile T. rex, and questioned whether both labels were necessarily more profitable.
“I don’t think it had any impact on the price because either way this is a beautifully complete, beautifully preserved and extremely rare example,” Aaron said.
But Pete Larson, a fossil expert known for his involvement in the excavation of two of the world’s most famous T. rexes – Sue and Stan – said he believed Chomper was Nanotyrannus. The specimen appeared in a 2020 episode of the Discovery Channel documentary series “Dino Hunters,” in which Larson pointed to the size of the hand bones and apparent fusion of the nasal bones as evidence that it was not a T juvenile rex.
“There’s a group of scientists who say it’s a juvenile T. rex and there’s a group of scientists who say it’s a Nanotyrannus,” Larson said, in an interview, of the choice in front of the gallery . “So they will choose the one who earns the most.”
Another specimen sure to shape the debate in the coming months is a paleontological marvel known as the Dueling Dinosaurs, a remarkably well-preserved Tyrannosaurus fossil that was discovered alongside the remains of a Triceratops, giving the impression that the animals might have been dead. while they fight each other.
The Dueling Dinosaurs specimen — which was discovered by a team led by Clayton Phipps, the same fossil hunter who excavated Chomper — has remained out of reach of researchers for years, holed up in storage during a court battle over who owned. But after the legal issues were resolved, the North Carolina Museum of Natural Sciences acquired it in 2020. This spring, the museum plans to open an exhibit where the public can tour the Dueling Dinosaurs while paleontologists are actively studying It.
One of the questions they will study is how exactly to classify Tyrannosaurus.
“We have to solve what, in my career, has been one of the most complex questions to address, because you have to distinguish so many variables,” said Lindsay Zanno, head of the museum’s paleontology department, listing growth, sex and fossilization . process as examples. “This is why it has perplexed the scientific community for years.”
The origin of the paleontological debate dates back to 1942, when an expedition from the Cleveland Museum of Natural History unearthed a 22-inch dinosaur skull in Montana. It was originally identified as a Gorgosaurus, but in the 1960s a new analysis argued that it belonged to a juvenile T. rex.
The debate has raged ever since. Even for non-scientists, there are clear differences between that specimen’s skull and those of adult T. rexes: the smaller skull has a thinner snout and thinner, more blade-like teeth. In the late 1980s, research led by paleontologist Robert T. Bakker argued that those differences, among many others, indicated that the specimen was a new species. He named it Nanotyrannus lancensis.
But about a decade later, paleontologist Thomas Carr made the most detailed argument yet that the 1942 specimen was actually a juvenile T. rex, attributing the differences to its immaturity. “Every bone in the skeleton of these animals changes as it grows,” said Carr, who has studied the question for more than 20 years.
Since the turn of the century, the debate has been revived by the discovery of new specimens, including a 21-foot-long one called Jane. One of the specimens in Woodward’s study was unearthed in Montana in the early 2000s and is on display in Rockford, Illinois, at the Burpee Museum of Natural History.
In the latest foray into the debate, Nick Longrich, a paleontologist at the University of Bath, has argued that Nanotyrannus is a distinct species, countering Woodward’s key conclusion about Jane and another specimen in a preprint of a paper that caused a stir among his colleagues at the October meeting of the Society of Vertebrate Paleontology.
“It’s almost become religious,” Longrich said of the passions stirred in the debate, describing it as “one of the ways you signal group identity” in paleontological circles.
But science, of course, is based on evidence, and many paleontologists believe that more needs to be done to end this dispute. This is where some become concerned about the growing market for dinosaur fossils at auction houses and art galleries.
Academic paleontologists see the surge in dinosaur prices – following the sale of T. rex Stan in 2020 for $32 million – as a growing crisis in their field, fearing that important specimens could end up beyond the reach of researchers.
Aaron, of the London gallery, said he hopes Chomper goes to a museum where scientists can study him, but there is no guarantee.
“We need more specimens to solve the mystery,” said David Evans, a paleontologist at the Royal Ontario Museum. “And this is exactly the kind of sample scientists need.”
Kirsten Noyes contributed to the research.