A Tyrannosaurus rex (T-Rex) skeleton nicknamed “Gus” sold for $50.1 million at a Sotheby’s auction in New York on Tuesday, becoming the most expensive dinosaur fossil ever sold.

The specimen is one of the world’s most complete T-Rex skeletons, consisting of 183 fossilised bones. It was discovered in 2021 on a ranch in South Dakota.

“Gus” lived during the Maastrichtian Age, approximately 66–72 million years ago, a period characterised by a warm climate, high sea levels and vast coastal plains that were frequently flooded.

The skeleton measures 11.6 metres (38 feet) in length, making it one of the largest T-Rex specimens ever discovered. It is approximately 63% complete.

The auction, won by an anonymous buyer, highlights the growing market for dinosaur fossils—a trend criticised by some palaeontologists, who regret that scientifically important specimens are ending up in private collections.

“The United States is the only country in the world where fossils of this kind are considered private property,” Cassandra Hatton, Sotheby’s Head of Science and Natural History, told Agence France-Presse (AFP) before the auction.

The previous auction record for a dinosaur fossil was held by “Apex,” a Stegosaurus skeleton purchased for $44.6 million in 2024 by billionaire Ken Griffin.