NEW YORK, NY.- Sotheby’s sold an unusually complete stegosaurus fossil at auction Wednesday for a staggering $44.6 million, toppling the record fossil price that had previously been set by the king of the dinosaur world, Tyrannosaurus rex.

The unexpectedly high price — which was more than 10 times the low estimate — shows that the market for prehistoric specimens is continuing to explode, which concerns paleontologists who fear that scientists could be priced out of the market.

With its trademark back plates and cavernous rib cage, this stegosaurus, which is said to have walked the Earth about 150 million years ago in what is present-day Colorado, was nicknamed Apex because of its exceptional quality. It was the subject of a 15-minute bidding war with seven bidders from around the world on the phone.

The auction house confirmed that the buyer was American but declined to reveal the buyer’s identity, saying the person intended to “explore loaning the specimen to a U.S. institution.”

Four years ago, the commercial fossil market was jolted by the sale of a T. rex skeleton called Stan that fetched a record $31.8 million, setting off a gold rush for dinosaur fossils in the American West and alarm bells for academics who fear that the spiking prices could push fossils out of the reach of museums and universities that wish to study them.

The $44.6 million sale of the stegosaurus fossil, which includes buyer’s fees, eclipsed the record set by Stan, which ended up at a developing natural history museum in Abu Dhabi, the capital of the United Arab Emirates. Apex, which stands 11 feet tall and 27 feet long, is among the largest of its kind.

“I’m amazed at how much it went for,” said Jim Kirkland, the state paleontologist of Utah, who was invited to examine the specimen but declined because he did not want to promote a fossil that could be sold to a private owner.

Kirkland said that from the photographs he saw of the specimen, it could be scientifically valuable because of its completeness. (It contains 254 fossil bone elements out of an approximate total of 319, the auction house said.) He said he hoped that whoever bought it would fully document it and make the data available to researchers. “The whole thing should go through a CT scan,” Kirkland said.

Jason Cooper, a commercial paleontologist, discovered Apex in 2022 when he was walking around his property — which is near the Colorado town of Dinosaur — and found a bit of femur protruding from rock. He and his colleagues excavated it the next year.

Most of the high-profile dinosaurs sold at auction have been T. rexes, the most publicly recognizable and beloved dinosaur species. Sotheby’s sold a T. rex fossil named Sue at auction for $8.4 million in 1997, helping usher in a boom in the market for old bones. But it was the 2020 sale by Christie’s of the T. rex Stan that triggered the most recent flood of fossils in the market.

In 2022, a Deinonychus antirrhopus (the inspiration for the Velociraptors depicted in the film “Jurassic Park”) sold for $12.4 million and a Gorgosaurus fetched $6.1 million. That same year, Sotheby’s sold a single T. rex tooth for more than $100,000.

But there were also signs that sellers were overestimating the value of their offerings in search of another record-bringer like Stan.

Sotheby’s estimated that a T. rex skull it was auctioning in 2022 would fetch between $15 million and $20 million, but it sold for only $6.1 million. Christie’s withdrew a T. rex named Shen with a high estimate of $25 million from a 2022 auction after scientists said data about its completeness was misleading.

Jingmai O’Connor, a paleontologist at the Field Museum in Chicago, was conducting research in Montana when she heard the news of the Apex sale. “$44.6 million for a stegosaurus?” she said. “Sorry, the paleontologists around me are laughing.”

She said it was rare to find such a complete specimen but questioned how much scientific value the fossil might have, given the availability of so many partial skeletons.

“With $44 million to scientists,” she mused, “we could move forward our understanding of dinosaurs by decades.”

This article originally appeared in The New York Times.