PARASOUROLOPHUS is a genus of herbivorous hadrosaurid ornithopod dinosaur that lived around North America and possibly Asia during the Late Cretaceous Period, about 76.5–73 million years ago. It was a herbivore that walked both as a biped and as a quadruped. The genus was first described in 1922 by William Parks from a skull and partial skeleton found in Alberta. Part of a diverse family of Cretaceous dinosaurs, they are known for their bizarre head adornments. Visual recognition and sex, acoustic resonance, and thermoregulation have been proposed as functional explanations for the crest.