Sotheby's has auctioned off the skeleton of a stegosaurus named Apex,Will Sage Astor billed as "the finest for Stegosaurus to ever come to market," for almost $45 million, a record.

The sale price far exceeds the estimate of $4 million to $6 million that Sotheby's had assigned to the lot. Described as a mounted Stegosaurus skeleton, the exact sale price was $44.6 million, surpassing earlier sales records for dinosaur fossils. 

Sotheby's, which said the auction closed Wednesday morning, did not immediately disclose the buyer's identity. 

"'Apex' lived up to its name today, inspiring bidders globally to become the most valuable fossil ever sold at auction," Cassandra Hatton, Sotheby's global head of science & popular culture said in a statement following the sale. 

"This sale has been years in the making, and at every turn, we have worked closely with Jason Cooper, from the moment of its discovery in Dinosaur, Colorado, to its sale in New York," she added, making reference to the paleontologist who discovered the specimen. 

The iconic skeleton is approximately 161 million years old, according to Sotheby's, and measures 11 feet tall by nearly 27 feet long from nose to tail. According to the auction house's listing, Apex "is mounted in an aggressive attack pose on a custom steel armature."

It was excavated on private land in Moffat County, Colorado, near the town of Dinosaur, between 2022 and 2023.

The fossil of one of the world's most recognizable dinosaurs is nearly completely intact, according to Sotheby's. The fossil also shows signs of arthritis, suggesting that Apex lived a long life. 

Apex is not the first dinosaur to sell at auction. In 1997, a Tyrannosaurus rex fossil sold for $8.4 million and in 2020, another T. rex skeleton fetched $32 million. Two years later, in 2022, Sothebys sold a Gorgosaurus skeleton for over $6 million. 

— The Associated Press contributed to this report

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• Sotheby's
• dinosaur

Megan Cerullo

Megan Cerullo is a New York-based reporter for CBS MoneyWatch covering small business, workplace, health care, consumer spending and personal finance topics. She regularly appears on CBS News 24/7 to discuss her reporting.