Andy travels back 220 million years to the time of placerias, a giant hippo-like reptile that roamed the earth alongside dinosaurs. His mission is to make a clay model of the head of a placerias to replace the one that broke back at the museum. Along the way he comes face-to-face with a hungry coelophysis, one of the earliest known dinosaurs, with placerias on the menu for lunch. The question is, will Andy succeed in time before the museum opens?
