Long before humans appeared on the planet, dinosaurs ruled the earth. On a little off-coast island, a clan of lemurs finds a dinosaur egg, hatching. Since there are no parents, the lemurs take care of the newborn, Aladar. Years later, a medium meteor goes down close to the island and the shockwave forces its inhabitants to flee to the continent. There, Aladar and his family meet other dinosaurs for the first time as well as real dangers. The destruction caused by the meteor here has also forced a herd of different herbivores to move to a remote valley that can provide food and protection against the carnivorous predators following after. Since Aladar grew up with a different understanding of the ways of the world, his way of helping others first isn't accepted within the herd, but soon it is proven that reason may be better than panic.