Misty, the skeleton of a brontosaurus-like dinosaur uncovered in Wyoming four years ago, sold at auction Wednesday for 400,000 euros, or just under $550,000, The Guardian reported. As is typical for auction purchases of this size, the buyer has so far remained anonymous, according to the BBC.

The mostly intact, 14-foot high, 55-foot long diplodacus fossil was famously found by the sons of Raimund Albersdörfer, a "slightly harassed German paleontologist," according to The Guardian. The two boys ran to their father with news of a bone too large to carry.

Her name comes from the fossil-rich region where she was discovered, Mystery quarry, in 2009. Nine weeks of painstaking excavation later, she was brought to a conservation lab and eventually to master dinosaur builder Aart Walen, who mounted and prepared her for the auction, according to The Guardian.

The remains of diplodacus dinosaurs, which lived in western North America around 150 million years ago, are extremely rare and difficult to excavate, according to Errol Fuller, who curated the dinosaur's sale at Summers Place Auctions on Wednesday.

"There are probably about six of these in the great museums of the world, including in Pittsburg and Washington," Errol said. "You are talking about a very rare item indeed. Even if you were lucky enough to find one in the first place, the digging out and the preparation then involved is an enormous undertaking."

"The rock that it was embedded in would have been extremely hard to break away from the bones, and you couldn't go at it with a sledgehammer because the bones were vulnerable to breaking," he added.

Misty was the top prize at Summers in what was believed to be the largest fossil sale in British history, The Guardian reported. Also up for auction were the fossilized leg of a dodo bird (extinct bird species), a card game between taxonomically preserved squirrels, and the displayable body of a giant tortoise believed to be 245 years old upon its death.