A Carnotaurus attacks a herd of dinosaurs during the late Cretaceous period, leading to the destruction of an Iguanodon nest. However, one egg miraculously survives and is carried away by an Oviraptor. The egg's journey doesn't end there; it is subsequently picked up by a Pteranodon and eventually lands on a distant island. There, it is found by a group of lemurs who witness the hatching of the Iguanodon, deciding to raise it as their own and naming it Aladar.

Years pass, and Aladar grows into a strong and compassionate adult, living peacefully among his lemur family. Their tranquility is shattered when a devastating meteor shower strikes, decimating their island and forcing Aladar and his lemur family to flee in search of safety. On their journey, they encounter a diverse group of dinosaurs also struggling to survive. Among them is a herd led by the stubborn and traditional Kron and his lieutenant Bruton, who believe only the strongest should survive. Alongside them are Neera, Kron's compassionate sister, and Baylene, an elderly Brachiosaurus. As water and food become scarce, Aladar's innovative ideas and kind-hearted nature challenge the herd's survival-of-the-fittest mentality, encouraging them to work together as they attempt to find a new, safe haven.