Set 65 million years ago during the late Cretaceous Period, "Dinosaur" follows the adventures of an Iguanodon named Aladar, who is separated from his own species as a hatchling and raised on an island paradise by a clan of Lemurs. When a devastating meteor shower plunges their world into chaos, Aladar and several members of his Lemur family escape to the mainland and join a group of migrating dinosaurs desperately searching for a safe new nesting ground. With water and food in short supply and bloodthirsty predators posing an ever-present danger, the herd faces many life-threatening obstacles during the course of their treacherous trek. Aladar's innovative thinking and compassion for the "misfit" members of the herd brings him into conflict with Kron, the rigid and stone-hearted leader of the group, and his loyal lieutenant Bruton. Winning support from Kron's sister, Neera, Aladar reluctantly challenges the "traditional ways" and shows how being adaptable and working together is the best path for survival.