It is one of the largest and most complete skeletons ever found, Sotheby's said.July 14, 2026, 11:19 AMBidding is set to begin Tuesday for Gus, a 67-million-year-old T. rex skeleton, in what is expected to become the most valuable dinosaur ever put up for auction, according to Sotheby's.The auction for Gus is set to begin at $19 million and could reach $20-30 million, according to the auction house. According to Sotheby's, Gus is one of the most complete T. rex skeletons ever discovered. The skeleton is roughly 61% complete by bone elements and 75-80% complete by bone mass. One hundred and eighty-three fossil bone elements make up the dinosaur.In addition to it being one of the most complete, it is one of the largest T. rex skeletons ever found, Sotheby's said. The dinosaur stands about 12.5 feet tall and approximately 38 feet long. Gus the Tyrannosaurus Rex skeleton at Sotheby's auction house in New York City, July 1, 2026.Jordan Tovin/ReutersGus's skull is well-preserved, with 82% of its bones represented, Sotheby's said. Gus was discovered in 2021 in Harding County, South Dakota, in the northwest corner of the state. It was excavated over the course of five years, according to the auction house. Popular ReadsThe skeleton was transported to New York and went on display for public viewing at the Breuer building from July 1-14 before the auction. "This is our longest-term project ever," Cassandra Hatton, vice chairman and worldwide head of science and natural history at Sotheby's, said in a press video. "From the day that the first bone was discovered, we've been going back and forth to South Dakota to oversee this whole process, and finally, we're about to bring it to the public."Gus was named for Gary Licking, the rancher whose land the skeleton was found on. Licking died away before the completion of the project, according to Sotheby's. Sotheby's natural history auction includes numerous other fossils and items up for sale. It began at 10 a.m. on Tuesday.