The largest and best stegosaurus fossil ever discovered has sold for $44.6 million at Sotheby’s in New York, making it the most expensive of its kind ever sold at auction.

The rare find, named ‘Apex’ and exceeded estimates by more than 11 times, was discovered on the property of professional fossil hunter Jason Cooper, near the town of Dinosaur (“Dinosaur”) in Moffat County, Colorado, in May 2022.

Apex lived 146 to 161 million years ago in the Late Jurassic Period. It is 3.4 meters tall and 8.2 meters long from the snout to the tip of its tail. It is 30% larger than ‘Sophie’, the most complete stegosaurus specimen to date, which is kept at the Natural History Museum in London.

After the sale, the anonymous buyer emphasized that “the fossil is one of the most important specimens ever found. Apex was born in America and will stay in America!”

Over the past twelve years, Cooper has spotted ten dinosaurs on his land, and Apex was found during a walk for his 45th birthday. The stegosaurus has been carefully cleaned and assembled by him and his team, and research has shown that it was a robust animal with signs of rheumatoid arthritis, suggesting it lived to an advanced age, according to Sotheby’s.

It also showed no signs of collision injuries and its remarkably good condition is due to sandstone, the rock that protected its 319 bones from decay, the Guardian reports.