Parasaurolophus

Parasaurolophus is instantly recognizable by the dramatic curved crest sweeping back from its head — in adults it could reach over 1.8 meters long. For a long time, scientists proposed all kinds of uses for it: a snorkel for swimming, an enhanced sense of smell, or even a weapon. The answer turned out to be far more interesting.

The crest is hollow, containing a complex network of nasal passages that loop from the nostrils up through the crest and back down to the lungs. By computer modeling these passages, scientists have been able to digitally 'play' a Parasaurolophus — and the sound is a deep, resonant trombone-like call, somewhere between a foghorn and a didgeridoo. It likely used this call for long-distance communication across the floodplains of Late Cretaceous North America.

Parasaurolophus was a hadrosaur — a 'duck-billed dinosaur' — and hadrosaurs were among the most successful dinosaur groups of the Late Cretaceous. They had sophisticated dental batteries: hundreds of small teeth tightly packed into a surface that constantly replaced itself, perfectly adapted for grinding tough vegetation.

Like other hadrosaurs, Parasaurolophus could move on two legs or four, switching between gaits depending on speed and terrain. It was social, living in herds, and may have cared for its young — evidence from closely related hadrosaurs suggests some degree of parental behavior.