The little Iguanodon Aladar lives in the late Cretaceous period, having grown up since childhood on a small, idyllic island paradise. Raised by a family of lemurs, Aladar has never seen another of his own kind and has spent his days carefree with his lemur friends. An unexpected meteor shower destroys Aladar's island home, forcing him and his lemur companions to flee to the mainland. At this time, due to the warming atmosphere, water sources are becoming increasingly scarce. Aladar and his friends encounter a herd of dinosaurs migrating in search of a new habitat and join them. Thus, Aladar and his companions embark on this exceptionally arduous journey of migration.