More than three decades ago in South Dakota, an amateur paleontologist named Stan Sacrison discovered a titan of the ancient Earth: the fossil of a mostly complete, 39-foot-long Tyrannosaurus rex. Nicknamed “Stan” after its discoverer, the beast was excavated in 1992 and has long been housed at the private Black Hills Institute of Geological Research in Hill City, South Dakota. But even if you’ve never been there, chances are good that you’ve seen this particular T. rex. Dozens of high-quality casts of its bones are on display in museums around the world, from Tokyo to Albuquerque, New Mexico.

Now, an auctioneer’s hammer has thrown Stan’s future into question, with the dinosaur bones sold off to the highest—and, so far, anonymous—bidder, stoking