Saurolophus
Saurolophus had a 5 inch (13 cm) long bony spike extending up from its forehead. There is speculation that this spike was attached to a flap of skin that covered the nostrils and could be blown up for displays and noise-making. Many Saurolophus fossils have been found, including one with fossilized skin impressions, in Alberta, Canada and Mongolia, China.