Parasaurolophus. One of the most famous and recognizable members of the hadrosaurid family. It is known for the long crest that grows on its head. This crest is hollow and connected to the nostrils, allowing it to function as a resonator. Therefore, scientists speculate that the sounds produced by Parasaurolophus may have vaguely resembled a trombone. This dinosaur was huge, but not the largest in the family, reaching 9-10 meters in length and weighing 3-5 tons