Sotheby’s opened live bidding on a collection of fossils July 14, with the centerpiece being a rare 67-million-year-old Tyrannosaurus rex skeleton named Gus. Auction house officials expect the specimen to fetch up to $30 million.
Gus is billed as one of the largest, most complete T. rex specimens ever found. Discovered on a ranch in South Dakota, it comprises 183 fossil bone elements — roughly 61 percent complete by bone count, according to Sotheby’s. The missing bones have been replaced with replicas, and the whole thing is mounted in a custom steel armature posed as if hunting.
The trend of selling major dinosaur skeletons at auction in the U.S. started in earnest in 1997, when Sotheby’s auctioned Sue — the most complete T. rex on record — for about $8.4 million. That sale prompted new legal rules for fossil ownership.
Before Sue, there were no clear rules about fossil ownership. Court cases that followed established that whoever owns the land also owns the fossils, said Cassandra Hatton of Sotheby’s. The market has boomed ever since.
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But while Sue ended up at the Field Museum in Chicago, many recent high-profile fossils have gone to private collectors. Tech entrepreneur Dan O’Dowd owns a T. rex called Samson. A 2025 study found that more T. rex fossils are now in private hands than in public trusts.
In 2024, the auction house sold a Stegosaurus named Apex to hedge fund billionaire Ken Griffin for $44.6 million — a record. Last year, the only known juvenile Ceratosaurus went to an anonymous buyer for $30.5 million. Museums simply can’t compete at those prices.
Paleontologists see this as a growing problem.
Private collectors who buy fossils as luxury assets effectively remove them from science. Even if a collector loans a fossil to a museum — as Griffin did with his Stegosaurus at the American Museum of Natural History — such temporary arrangements violate a core principle of paleontology: scientific reproducibility, which requires that researchers have permanent access to the same specimens.
Established scientific journals won’t publish studies on specimens that aren’t held in a publicly accessible museum, said Stuart Sumida, a paleontologist at California State University, San Bernardino.
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The auction house describes holes in Gus’s jaw and elsewhere as tyrannosaurid bite marks — signs of a fight or scavenging. But the paleontologist disputes that. Puncture marks from teeth are irregular and cause splintered fractures, he said.
The holes on Gus are perfectly round and smooth-edged, more consistent with infections. “It’s much sexier to say they’re puncture wounds, but this isn’t how puncture wounds look,” he said. “T. rex probably just had really bad breath.”
When asked about the origin of the bite-mark claim, Hatton replied that the bite marks are “very clear” and include lateral bites. She did not specify who conducted that analysis. The description in the auction catalog offers no supporting evidence for the interpretation.
This kind of marketing is part of a broader pattern, paleontologists argue. Auction houses sometimes play fast with science to make fossils more appealing to untrained buyers. The central problem, however, remains access: once a fossil enters a private collection, it’s lost to the scientific community forever — unless the owner chooses to donate it.
It’s a familiar dynamic in other fields, too. Rare artifacts, manuscripts, and even genetic sequences have gone through similar tensions between private ownership and public stewardship. The difference with fossils is that they are irreplaceable. A painting can be copied. A fossil is a one-of-a-kind record of deep time.
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The Society of Vertebrate Paleontology, led by Sumida and Kristi Curry Rogers of Macalester College, is trying a new approach. Instead of fighting the sales, they are working to set up the society as a liaison between private collectors and museums. The goal is to persuade buyers to donate fossils immediately after purchase, rather than keeping them as trophies.
“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 said.
The society is in talks with some collectors and museums, though Sumida declined to share specifics.
He said they don’t yet have a plan for Gus’s buyer, but they might develop one depending on who purchases the fossil. Thomas Holtz, a tyrannosaur specialist at the University of Maryland, said of Gus: “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. Let us hope that whoever acquires it keeps this in mind.”
