Parasaurolophus

Parasaurolophus is one of the most recognisable duck-billed dinosaurs, known from Late Cretaceous rocks across western North America. Reaching about ten metres in length and weighing up to four tonnes, it was a massive animal built to browse both low shrubs and tree canopies. Its defining characteristic is the long, backward-curving crest that projected up to nearly two metres from the back of the skull. Computed tomography scans reveal internal air passages winding from the nostrils up to the crest tip and back down to the throat, allowing the dinosaur to produce low-frequency honks or bellows that could carry over long distances. Parasaurolophus walked primarily on all fours when feeding, but could rise on its powerful hindlimbs to flee predators such as gorgosaurs.

Its backward-sweeping tubular crest contained complex hollow airways that functioned as a low-frequency acoustic resonator.

Where and when

Parasaurolophus lived in the Late Cretaceous, from 76.5 to 73 million years ago (Campanian age). Its remains come from Canada and United States, in the Dinosaur Park Formation.

The numbers

Length 10 m (estimates run from 9.5 to 11 m). Mass about 3.2 t. Hip height about 3.2 m. That is 5.9 human-lengths, or 0.89 of a double-decker bus. These are estimates from near-complete skeleton; fields marked estimated by the site are length, mass, hip height.

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