Forget the sale of the century. The auction house Sotheby’s has geared up for the sale of the epoch. On July 14 it opened live bidding on assorted fossils, but the pièce de résistance is lot 20, a rare 67-million-year-old Tyrannosaurus rex skeleton.

The specimen—dubbed Gus—is billed as one of the largest, most complete T. rexes ever found. Gus is expected to fetch up to $30 million and will go to the highest bidder, whether public museum or private collector. The latter have played an increasingly prominent role in buying fossils, with auction houses, according to paleontologists, contributing to the trend by building hype. But when private collectors swoop in and buy fossils at auction as luxury assets, those pieces of history are effectively lost to science.

By nearly all accounts, Gus is a big deal. In its description, Sotheby’s boasts that the specimen, which was discovered on a ranch in South Dakota, comprises “an incredible 183 fossil bone elements” making it “approximately 61% complete by bone count.” The fossil remains have been mounted in a custom steel armature along with replicas of the missing bones. The result is a reconstructed skeleton posed as if in hot pursuit, its mouth full of dagger teeth ready to tear into prey.

“It does seem to be a spectacular specimen,” says Thomas Holtz, a tyrannosaur specialist at the University of Maryland. The completeness of the skeleton and the high quality of the bone make Gus “scientifically significant,” he says.

Gus is the latest major dinosaur fossil to go up for sale at auction in the US. That trend began in earnest in 1997 when Sotheby’s auctioned Sue, the most complete T. rex on record. That specimen sold for roughly $8.4 million—the most money ever paid for a fossil at auction at the time.

“Before Sue was sold, there were no laws about who owned fossils. There was no value truly ascribed to them,” says Cassandra Hatton, vice chairman and head of the science and natural history department at Sotheby’s. In many other countries the state owns the fossils. But court cases around Sue clarified that in the US, whoever owns the land also owns whatever fossils are on it, Hatton explains. The market has been booming ever since.

But whereas Sue went to a scientific institution—the Field Museum in Chicago—in recent years ultrarich individuals have been snapping up dinosaur fossils at auctions for their private collections, prompting paleontologists to be concerned about the fate of rare specimens. Tech entrepreneur Dan O’Dowd owns a T. rex called Samson. And he’s not the only private collector to own a tyrant lizard king. A study published in 2025 found that there are more fossils of T. rex in private collections than there are in public trusts.

It’s not just T. rex that’s ending up in personal coffers. In 2024, Sotheby’s sold a Stegosaurus named Apex to hedge fund billionaire Ken Griffin for the record-setting sum of $44.6 million. And last year the auction house sold the only known juvenile Ceratosaurus in the world to an anonymous buyer for $30.5 million. These examples highlight another trend: As prices soar, museums simply cannot compete at auction.

Credit: Courtesy of Matthew Sherman/Sotheby’s

Auction houses say the sales help science by rescuing fossils from the erosion that occurs when they are exposed to the elements, and by helping to get them expertly excavated, prepared, and assessed.

“If a fossil is not excavated, it’s lost to everyone,” Hatton says.

Paleontologists counter that the incentive to sell specimens to the highest bidder and appeal to high-net-worth collectors actively undermines science every step of the way. That begins at excavation, with commercial outfits that take the fossils out of the ground but fail to exhaustively document the geological context in which a fossil was found, which is essential for understanding the age of the organism, how it died, and the ecosystem it inhabited. Mounting the bones for artistic display makes them impossible to study using modern techniques such as computed tomographic imaging, which can reveal hidden features of fossils noninvasively.

Paleontologists also argue that the auction firms play it fast and loose with science to market the fossils in a way that may make them more appealing to untrained buyers. In the case of Gus, Sotheby’s describes holes in the jaw and elsewhere on the specimen as tyrannosaurid bite marks—signs that Gus might have battled with or been scavenged by his own kind. The description does not offer any evidence to support this interpretation of the holes, nor does it mention alternative explanations for such damage.

It’s a dramatic story, but it’s probably wrong, according to Stuart Sumida, a paleontologist at California State University, San Bernardino. Puncture marks are irregularly shaped and have splintered fractures around the edges. The holes on Gus’ bones, in contrast, are perfectly round and smooth-edged. Holes like these are common on tyrannosaur bones and have been previously hypothesized to be the result of infections. “It’s much sexier to say they’re puncture wounds, but this isn’t how puncture wounds look,” Sumida says of the hole in Gus’ jaw. “T. rex probably just had really bad breath.”

When asked by WIRED about the origin of the bite-mark claim, Hatton replied, “The bite marks are very clear, and are not all straight punctures but lateral bites where you can clearly see the shape of the tooth. You can also tell from the edges of the hole whether the break is clean, or if the hole is gradual (which would be more likely the result of a parasitic or other infection that gradually and evenly eats the bone).” She did not indicate where this analysis came from.

But the central issue with auctioning fossils, researchers contend, is that when specimens end up in private hands, they become unavailable for scientific study. Even if a private collector loans a fossil out for display or study at a museum, as happened last year when the American Museum of Natural History in New York City secured a four-year loan of Griffin’s Stegosaurus, such an arrangement violates a central tenet of paleontology: Scientific reproducibility requires that researchers other than those conducting the original examination have access to those same fossils in perpetuity.

That approach allows paleontologists to validate findings, test new hypotheses, and build knowledge of the past. To ensure access, fossils must be held in public repositories on a permanent basis. So vital is this covenant that established scientific journals won’t publish a study on a specimen that isn’t in the custody of a publicly accessible museum, Sumida explains.

Everything scientists have been able to piece together from fossils about prehistory—from the origin of multicellular life to the dawn of humankind—rests on this system.

“A scientifically important fossil isn’t just a static object; it’s a permanent source of data that future generations of scientists will study with tools that haven’t even been invented yet—but only if the fossil remains in the public trust,” says Kristi Curry Rogers, a paleontologist at Macalester College. “Think about all the cool discoveries that have been made in the last 50 years about dinosaur diets, body temperatures, coloration, reproduction, vocalization, neurobiology—none of these discoveries would have been possible if the fossils had disappeared into private collections.”

Sales of fossils to private individuals in the US won’t stop, Sumida acknowledges. So he and Rogers are taking a different tack to help keep important fossils in science’s fold. In their respective roles as president and vice president of the Society of Vertebrate Paleontology, they are working to set up the society to act as a liaison between private collectors and museums. Their goal is to persuade private collectors to donate the fossils they buy to science museums right after the gavel falls rather than keeping them as trophy acquisitions.

“When it comes to these public auctions of our shared history, the best outcome is when those with the means to acquire an extraordinary fossil choose to immediately place it in the public trust, where everyone benefits,” Rogers says.

Private buyers can avoid the bad PR that comes from opposition to these sales by making their purchase anonymously, which could hinder efforts to persuade them to engage in philanthropy. But the Society of Vertebrate Paleontology is hoping that if it can convince even just a few known individuals to donate their fossils to science, they, in turn, will influence others to do the same.

The society is in talks with some collectors and museums, though Sumida declined to share specific details. It doesn’t have a plan in place to approach Gus’ buyer, but it might develop one depending on who purchases the fossil.

“A specimen of this quality deserves to be in a museum collection so that not merely the current generation but future researchers (to say nothing of museum-goers) would be able to study and admire it far into the future,” Holtz says of Gus. “Let us hope that whoever acquires it keeps this in mind.”

This story originally appeared at wired.com.