Late Cretaceous dinosaur (about 75 million years ago), Parasaurolophus could measure up to 32 feet tall and weigh more than 2 tons! This large, flat-billed herbivore is known for its long bony crest surmounting its head. This impressive ridge could be up to 6 feet long and probably had several functions. Hollow and connected to the nose, it seems that it allows the Parasaurolophus to emit sounds and thus communicate with its congeners. Another hypothesis is that this ridge also served to regulate the temperature or played a role of seduction during the period of love.