This is the skull of Parasaurolophus, it was used to emit extremely low frequency sounds. Each individual Parasaurolophus had it’s own call, sort of like a fingerprint. Comunication was a very big part of their lives it allowed them to socialize, warn each other and perform mating rituals. An isolated Para is a dead Para so these social creatures formed herds, where do you think the saying “safety in numbers” came from. A Parasaurolophus skull is extremely complicated with varying parts from cranial crests to the central braincase. It would be far to complicated to explain the entire functionality and theories of the crest (let me know if you want a post explaining it).