Billionaire investor Ken Griffin, founder and CEO of hedge fund Citadel, purchased a late-Jurassic stegosaurus skeleton for $44.6 million at Sotheby’s Wednesday, marking the most valuable fossil ever sold at auction.

The 150 million-year-old stegosaurus named “Apex” measures 11 feet tall and nearly 27 feet long from nose to tail and it is a nearly complete skeleton with 254 fossil bone elements. Apex was only expected to sell for about $6 million.

Griffin won the live auction in New York Wednesday after competing with six other bidders for 15 minutes. He intends to explore loaning the specimen to a U.S. institution, according to people familiar with his plans.

“Apex was born in America and is going to stay in America!” Griffin said after the sale.

Apex shows no signs of combat-related injuries or evidence of post-mortem scavenging, Sotheby’s said. The stegosaurus was excavated on private land in Moffat County, Colorado.

In 2018, Griffin gifted $16.5 million to Chicago’s Field Museum to help fund the display of a touchable cast of the biggest dinosaur ever discovered — a giant, long-necked herbivore from Argentina.

In 2021, he paid $43.2 million for a first-edition copy of the U.S. Constitution, outbidding a group of cryptocurrency investors. He later loaned it to the Crystal Bridges Museum of American Art in Arkansas.