The largest and most complete stegosaurus fossil ever discovered sold for $44.6m at Sotheby’s in New York on Wednesday to become the most valuable fossil sold at auction. The dinosaur remains, nicknamed “Apex”, exceeded its pre-sale low estimate by more than 11 times. It was discovered on privately owned land in Moffat County, Colorado, fittingly near the town of Dinosaur, by commercial palaeontologist Jason Cooper at his property in 2022. “Apex” measures 3.4 metres (11ft) tall and 8.2 metres (27ft) long from nose to tail, more than 30% larger than “Sophie”, the previously most intact stegosaurus specimen, which was on display in London’s Natural History Museum. It was sold to an anonymous buyer who intends to explore loaning the specimen to a US institution. After the sale, the buyer remarked: “Apex was born in America and is going to stay in America!” Cassandra Hatton, Sotheby’s global head of science and popular culture, said: “‘Apex’ lived up to its name today, inspiring bidders globally to become the most valuable fossil ever sold at auction. “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. “I am thrilled that such an important specimen has now taken its place in history, 150m years since it roamed the planet. This remarkable result underscores our unwavering commitment to preserving these ancient treasures.” “Apex” ranks high among the most complete skeletons ever found, with 254 fossil bone elements of an approximate total of 319. The skeleton belonged to a large, robust adult and there was evidence of rheumatoid arthritis, indicating that it lived to an advanced age, according to Sotheby’s. The specimen showed no signs of combat-related injuries or evidence of postmortem scavenging. It was preserved in hard sandstone, which protected the bones from being distorted. “Apex” was the star attraction of Sotheby’s natural history auction, with other lots including meteorites, minerals, gogottes and, for the first time, paleolithic tools. The auction made $45.8m (£35.2m) overall, the highest ever total for a natural history auction.