| Director | Eric Leighton, Ralph Zondag |
|---|---|
| Genre | adventure film |
| Runtime | 82 min |
| Country | United States |
| Budget | $127.5 million |
| Box office | $349.8 million |
A Carnotaurus ambushes a herd of dinosaurs and tramples an Iguanodon nest. One surviving Iguanodon egg journeys to a tropical island inhabited by prehistoric lemurs by the flight of a pterosaur. Plio, the daughter of lemur patriarch Yar, names the newly-hatched baby Aladar and raises him alongside her daughter Suri, despite Yar's initial objections.
Years later, an adult Aladar watches the lemurs take part in a mating ritual, where Plio's teenage brother Zini fails to attract a mate. Moments after the ritual ends, a colossal asteroid crashes into the sea, releasing explosive shockwaves and fire clouds that destroy the island. Aladar and Yar's family flee and swim to the mainland, mourning for the loss of all lemurs before moving inland.
While crossing a burnt desert, the group is attacked by a pack of Velociraptor. They escape them by joining a multi-species herd of dinosaur refugees heading to the Nesting Grounds, an oasis left undevastated by the destruction of the asteroid. The herd's callous leader, Iguanodon Kron, forces the family to the back of the line, where they befriend a trio of elderly dinosaurs, Styracosaurus Eema, her pet Euoplocephalus Url, and her friend Brachiosaurus Baylene.
The herd travel for days to the site of a lake, only to find it seemingly dried up. Determined to reach the Nesting Grounds, Kron orders the herd to move on, and let the weakest perish. Realizing water is buried under the dried lake, Aladar digs with Baylene until they reach the water table, saving the herd from dehydration. Kron's sister Neera, impressed by Aladar's compassion, begins to grow closer to him. Kron sees Aladar's increasing popularity as a challenge to his dominance.
Meanwhile, a pair of Carnotaurus are hunting the herd. Kron's lieutenant Bruton and a scout are ambushed, but Bruton escapes injured to warn Kron of the approaching predators. Kron has the herd abandon Aladar, the lemurs, the elderly dinosaurs, and Bruton, hoping they will slow down the pursuers. The group takes shelter in a cave during a rainstorm. The Carnotaurus track the group to the cave and attacks them during the night. Bruton sacrifices himself to cause a cave-in that kills one of the Carnotaurus, forcing the other to retreat.
Venturing deeper into the cave, the group reaches a dead end, causing Aladar to briefly lose hope. Baylene reproaches him for giving up, and uses her strength to smash through the wall, revealing the lush Nesting Grounds on the other side. As they briefly celebrate their new home, Eema notices that a landslide has collapsed the usual entrance into the valley. Aladar rushes to warn Kron, attempting to force the herd to climb the rubble, unaware of the sheer drop on the other side. Seeing the warning as a challenge for the position of herd leader, Kron fights Aladar and nearly kills him, until Neera intervenes by shoving Kron away from Aladar. Exasperated by Kron's cruelty, Neera and the herd turn against Kron by leaving with Aladar, while Kron stays behind to climb the rubble himself.
The surviving Carnotaurus arrives and charges at the herd. Aladar rallies them together to outnumber the Carnotaurus. Sensing easier prey, the Carnotaurus decides to go after the isolated Kron instead. Aladar and Neera rush to his aid, as Kron is mortally wounded. Aladar pushes the Carnotaurus towards the edge of the drop, where the ground gives way, causing the predator to fall to its death. Aladar and Neera mourn for Kron's demise, before leading the herd to the Nesting Grounds. Some time later, a new generation of dinosaurs hatches, among them are Aladar and Neera's children. The lemurs find more of their own kind.