PARASAUROLOPHUS (PAIR-ah-SORE-ol-OH-fus)

Period: Late Cretaceous

Order, Suborder, Family: Ornithischia, Ornithopoda, Hadrosauridae

Location: North America (Canada, United States)

Length: 33 feet (10 meters)

Parasaurolophus was an interesting-looking dinosaur. While it looked normal from the neck down, it looked almost as if it had a trombone on its head. And in a way, it did.

Parasaurolophus is one of many hadrosaurs from the Late Cretaceous of North America. Its name, which means "like Saurolophus," refers to the resemblance of the crests of these two duckbilled dinosaurs. However, the crest of Saurolophus was solid bone and the crest of Parasaurolophus was hollow. The hollow space within the crest of Parasaurolophus reached the nostrils and looped down to connect to the back of the throat. This crest was the animal's nasal cavity moved on top of its head.

This crest, seen also in other lambeosaurine hadrosaurs, has attracted much attention. At first, paleontologists thought this crest was used underwater, perhaps as a snorkel or a place to store extra air. Other suggestions included extra space to increase the animal's sense of smell or an area used to cool its brain. The function of the crest is now thought to relate to hadrosaur social behavior. Because of their size and shape, crests could have been for display. They may have helped other members of its species identify the animal, and the crest may have shown how old the animal was and its sex.

Also, because, the crest was hollow and connected to the lungs, it would have made a resonating chamber. Sounds would have been made by a vocal organ or voice box and "pushed" through the crest, making a deep honking call. In this way, the animal could have communicated. All lambeosaurines would have used their "voices" to announce themselves, to warn their hatchlings, and to challenge other animals that invaded their territory.