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Was the “Nanotyrannus” real? Or just a young T. rex? Does it matter?

It seems a little strange to have strong feelings about a dinosaur that probably never existed. And yet, if you want to get dinosaur fans riled, you need not say much more than “Nanotyrannus.”

The specter of so-called “Nanotyrannus” raised its diminutive but fearsome head recently thanks in part to a skeleton that is up for sale for a whopping $20 million. To most, these fossils, and others attributed to “Nanotyrannus,” are nothing more (or less!) than that of an adolescent Tyrannosaurus rex, before they underwent a growth spurt turning them into 9-ton chomp monsters. To others, though, “Nanotyrannus” is a distinct species that lived alongside T. rex in the waning days of the Cretaceous. Dinosaur Balloon Ball

Was the “Nanotyrannus” real? Or just a young T. rex? Does it matter?

Whatever species the bones truly belong to, however, “Nanotyrannus” has become a 68-million-year-old sore spot that’s done more to inflate the asking prices of tyrannosaur fossils put up at auction than inform our understanding of the deep past.

For those who don’t closely follow dinosaur biographies, here’s the basic history. Way back in 1946, paleontologist Charles Gilmore published a paper on a beautiful, strange skull that had been excavated from the Cretaceous-age Lance Formation of Montana. The fossil clearly represented a tyrannosaur—a family of carnivorous dinosaurs with tiny arms—but Gilmore couldn’t find a good fit among the species known at the time. He settled on calling the dinosaur Gorgosaurus lancensis, proposing that it was a new species of Gorgosaurus, a tyrannosaur previously found in Alberta, Canada.

No one really paid much attention to the new dinosaur. Even Gilmore pointed out that experts had been getting a little tyrannosaur-happy, declaring new kinds based on incomplete remains like teeth. But in 1988, paleontologists Robert Bakker, Philip Currie, and Michael Williams described Gilmore’s strange skull anew. The fossil came from the same stomping grounds as T. rex, they noted, and wasn’t really a match for Gorgosaurus either. The small skull appeared to be something new, they argued, with fused skull bones hinting that the dinosaur was an adult despite being less than half the size of T. rex. The skull Gilmore had described decades earlier became “Nanotyrannus lancensis,” the “small tyrant” of the Lance Formation.

I don’t mean to throw scientific shade, but I put “Nanotyrannus” in quotation marks because that’s standard practice for species that have been named but whose categorization as a unique species is considered dubious or invalid or are otherwise obsolete. The consensus among tyrannosaur experts today is that there’s no solid case for “Nanotyrannus.” Despite decades of debate and multiple studies, no one has found a slam-dunk “Nanotyrannus” fossil or been able to identify a telltale trait that truly distinguishes the infamous skull from what we’d expect of a young T. rex. Studies of tyrannosaurs and other dinosaurs found that fused skull bones are not always indicators of adulthood, and other small differences—such as a few more teeth in the jaws of “Nanotyrannus” compared with T. rex—may just vary between individuals and with age. Some fossils once thought to be candidates for “Nanotyrannus,” such as a teenage tyrannosaur nicknamed Jane, have turned out to be that of young T. rexes. Even a new study claiming to validate the existence of “Nanotyrannus” hasn’t swayed the broader paleontological community. Fossils that could in theory be categorized as belonging to a small adult tyrannosaur are best understood as young, gawky-looking T. rexes that behaved differently from adults as they awaited their big growth spurt. (Even dinosaurs had awkward phases.)

It’s worth noting here that for die-hard dinosaur nerds, the stakes are low. Even if someone were to go out to the outcrop tomorrow and find a new specimen that proves that “Nanotyrannus” was a small carnivore distinct from T. rex, such a discovery wouldn’t do all that much to change our view of what life was like in the 2 million years or so before an asteroid-sparked catastrophe would wipe out 75 percent of Earth’s species. Some fossils would get reshuffled, and we’d know that young T. rex likely competed with “Nanotyrannus” for food. Such a discovery would also send paleontologists back to the rock in search of more evidence as to what the juvenile T. rex and young “Nanotyrannus” were really like. It might all make for a fun flurry of news coverage because T. rex drama is the junk food of fossil news (and I realize I’m saying this as someone who’s written about the carnivore more than a few times). But we’ve been through such lumping and splitting with other dinosaur species before—such as the enormous duckbill “Anatotitan” turning out to be the adult Edmontosaurus—and the results were not earthshaking for our concept of the Cretaceous world.

T. rex has a cult of personality that extends far beyond the academic literature; anything related to the dinosaur or its lore gets an outsized amount of interest. The dinosaur is an icon, and so claiming that some T. rex fossils are in fact the bones of a similar but rarer—and contested—species has only reinforced an auction market where the filthy rich are looking for a petrified status symbol. In 2013 private fossil dealers claimed they had uncovered a skeleton that would, once and for all, prove that “Nanotyrannus” was real and placed the fossil up for auction as part of a “dueling dinosaurs” pair. Buzz around the auction speculated that the fossils could go for as much as $9 million, but years after an offer of $5.5 million failed to meet the reserve, the fossils were sold to the North Carolina Museum of Natural Sciences for an undisclosed amount in 2020. The fact that the fossil is being cared for in a museum is a positive, though to date, no actual study of the tyrannosaur has been published.

The tyrannosaur skeleton recently listed for sale at the David Aaron art gallery in London for $20 million is another example of Mesozoic monster marketing. The skeleton has the svelte look of a juvenile T. rex, or, for true believers, represents an elusive “Nanotyrannus.” The gallery lists the skeleton as a juvenile T. rex, but in a description directly references the “Nanotyrannus” debate to stir in a little extra hype around the fossil (whose fate should really be decided by scientists, not the free market).

Whatever you want to call “Chomper”—as the fossil has been nicknamed—it should be in a museum. The dinosaur might not be able to tell us all that much about the past. But as a creature that lived and died at a time when our ancestors were snuffly little bug-eaters, it’s literally priceless, and it should be available to be viewed by the public, not by whomever its eventual ultra-wealthy owner decides to have over for dinner. At the same time, although the gallery might claim that any museum is welcome to pony up $20 million, I’d be pretty pissed off if an institution reinforced the off-the-rails dinosaur market this way. That much money could fund fieldwork for decades or otherwise be put to better use through research, collections management, and outreach rather than being blown on a single skeleton that would then have to be hyped to attract enough visitors to make back the purchase price. All that for a skeleton that in all likelihood will have the big reveal of “Yeah, it’s another young T. rex” after all the headlines and overwrought debate. It’s time to stop this tiny tyrant from causing such big headaches.

Slate is published by The Slate Group, a Graham Holdings Company.

Was the “Nanotyrannus” real? Or just a young T. rex? Does it matter?

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