A dinosaur from the Upper Cretaceous period (approximately 75 million years ago), the Parasaurolophus could measure up to 10 m and weigh more than 2 tonnes! This large herbivore with a flat snout is known for the long bony crest on its head. This impressive crest could measure up to 1.80 m in length and probably served several purposes. Hollow and connected to the nose, it appears that it enabled the Parasaurolophus to emit sounds and thereby to communicate with its congeners. Another theory is that this crest was also used to regulate the animal’s temperature.