Owning a piece of dinosaur history is looking to get especially pricey. This week, a Tyrannosaurus rex skeleton nicknamed “Gus” became the most expensive dinosaur fossil ever sold at auction. On Tuesday, Gus was sold at the NYC-based auction house Sotheby’s for an astounding $50.1 million. The sale, made to a currently unknown buyer, shatters the previous record for a dinosaur auction set just two years ago. Experts worry, however, that the private purchase will prevent further study of this truly unique specimen. Gus the record-breaker Gus was discovered in South Dakota five years ago by the company Theropoda Expeditions on the property of cattle rancher Gary “Gus” Licking. The property was located within the Hell Creek formation, a vast region stretching across Montana, Wyoming, and the Dakotas already known to contain a rich bounty of fossils from the late Cretaceous period right before dinosaurs went extinct. Licking sadly passed away before the dinosaur was fully excavated from the area in 2023, though the T. rex fossil was given the same nickname in his honor. By bone fossil count, Gus is about 61% complete. And though it isn’t the most intact T. rex skeleton ever found, Gus does have some special things going for it. For starters, it’s one of the largest dinosaurs of its kind ever unearthed, measuring 38 feet long and standing 12.5 feet tall, according to Sotheby’s. Its skull alone is 54 inches long. Gus is also notable for containing several gastralia, free-floating bones located in its abdominal wall. Only certain living reptiles, such as crocodiles, have these types of bones today.