Stegosaurus skeleton, nicknamed 'Apex,' sells for record $44.6M at Sotheby's auction

A nearly complete stegosaurus skeleton sold at a Sotheby's auction in New York on Wednesday for a record $44.6 million -- the most ever paid for a fossil.

The dinosaur, nicknamed "Apex" -- which lived between 146 and 161 million years ago in the Late Jurassic Period -- was originally expected to sell for between $4 million and $6 million, according to the auction house.

Sotheby's has said Apex is the "most complete and best-preserved Stegosaurus specimen of its size ever discovered."

The skeleton was discovered on private land in Moffat County, Colorado -- in northwestern Colorado and on the border with Utah and Wyoming -- in May 2022 by commercial paleontologist Jason Cooper, with excavation completed in 2023, according to Sotheby's. The county is an area where many other dinosaur fossils have been discovered and is home to the Dinosaur National Monument.

Apex measures 11 feet tall and 27 feet long from nose to tail. The skeleton consists of 319 bones -- 254 of which are fossils and the remainder being either 3D printed or sculpted. It's unclear if Apex was male or female.

"Judging from the overall size and degree of the bone development it can be determined that the skeleton belonged to a large, robust adult individual, and evidence of arthritis, particularly notable in the fusion of the 4 sacral vertebrae, would indicate that it lived to an advanced age," Sotheby's wrote on its website. "The specimen shows no signs of combat related injuries, or evidence of post-mortem scavenging, and exhibits a number of interesting pathologies."

Apex is not the first dinosaur to sell for millions. One of the largest and best-preserved skeletons of a Tyrannosaurs rex ever discovered -- nicknamed "Sue" -- sold at auction in 1997 for $8.4 million and is now on display at the Field Museum of Natural History in Chicago.

Sue was the most expensive fossil ever sold until another mostly complete Tyrannosaurus rex skeleton, nicknamed "Stan", was sold at auction in October 2020 for $31.8 million. Officials in Abu Dhabi's Department of Culture and Tourism told National Geographic they have the dinosaur and that the skeleton will be displayed in a new natural history museum set to open in 2025.

"'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 and popular culture, said in a statement to ABC News. "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."