Of all the dinosaurs in history, Parasaurolophus must have had one of the most distinctive-looking heads. The crest of this 33-foot long duck-billed dinosaur measured almost six feet in length and was made of a strong but hollow tube filled with nasal passages. These nasal passages connected from the creature's nostrils back to the very tip of the crest.
When scientists first discovered Parasaurolophus, it was thought that the crest was used as a kind of snorkel, but that could not have been farther from the truth since the tip of the crest didn't have an opening in it! There are plenty of other theories for how Parasaurolophus might have used this oddly shaped crest. It could have been used like a trumpet, making sounds to warn others of danger or to attract mates. These dinosaurs, which traveled in herds through the jungles of North America, had very good eyesight and may have used their unique headgear as a form of identification.