(New York, NY) -- A rare dinosaur skeleton is hitting the auction block at Sotheby's on Thursday. The bones of the Gorgosaurus, which is a cousin of the T. Rex, were found in Montana and are estimated to go for up to eight million dollars. It's the first time a complete skeleton of its type has come up for public auction. Experts say the Gorgosaurus, an apex carnivore, roamed the western United States and Canada about 77 million years ago.