The Parasaurolophus best

With a tail like a crocodile, a bill like a duck, and a crest on it's head that doubled as a wind instrument, Parasaurolophus was certainly one of the famous hadrosaur ever known. This giant plant-eater may have looked like a monster but in fact it traveled in herds of thousands as a defense against savage predatory dinosaurs. It communicated best by producing a low booming sound amplified by passages in it's long skull. The boom may have been used both as a warning sound and during courtship. The males probably had longer crests, as they would have used them in competitive displays to impress mates.