Dawn breaks over a lush Late Cretaceous forest. Mist hangs low across the riverbanks, and from within the fog comes a haunting, resonant call — a deep, echoing note that rolls through the valley. It is the voice of Parasaurolophus, one of the most striking of all herbivores. Its long, curved crest is more than decoration — it is a musical instrument, capable of producing sounds that can travel for miles. In this quiet world, sound is survival. It stands up on its two legs and gives out a broadcast call to the herd.