Pricey dino. The largest, most complete stegosaurus ever found sold for a record US$44.6 million at auction. The giant, 150-million-year-old fossil, nicknamed Apex, is 3.4 metres tall and 8.2 metres long. The skeleton shows signs of rheumatoid arthritis, which suggests that the animal lived to an advanced age. Apex was sold to an anonymous buyer, who wants to loan the specimen to a US institution.