A clan of lemurs including Plio, Yar, Zini and Suri are seen living on Lemur Island. When a dinosaur egg falls on the island, all the lemurs scatter in a frenzy. As the other lemurs gather around the fallen egg, Zini tries to get closer, but his father Yar stops him, telling him it's not safe. After the egg cracks, Yar's daughter Plio opens the shell and is happy to see a baby Iguanodon. After some protesting from Yar, he allows Pilo to raise the hatchling, whom she names Aladar.
Years later on Lemur Island, Aladar has grown up a vegetarian dinosaur, thanks to Plio's care. Shortly after a mating ritual takes place, Suri climbs up a tree to see a gentle meteor shower that had began to fall out of the sky, which ominously increases and lands in the sea miles away. The meteor shower increases until an even brighter object grabs everyone's attention. They all look up to see a large asteroid falling from the sky towards Earth. The massive object plummets from the sky and into the sea miles offshore. Creating a bright flash and a massive mushroom cloud, the island is then struck by two violent shock waves that blast everyone down. Moments after that, fragments from the now-vaporized space rock begin to spread out in all directions from the impact area. A massive cloud of fire made from the vaporized material also spreads out towards the island, which is soon bombarded by many of these small fragments.
Aladar promptly flees and takes Plio, Yar, Suri and Zini on his back. Aladar races away towards the other side of the island as fragments rain down around him. Aladar makes it to the other side of the island. But at this time, the cloud of fire strikes the other side of the island. He turns around to see the massive cloud of fire barreling towards him. He quickly jumps into the sea as the cloud passes over. Aladar and his lemur family swim to the mainland, only to find out that it was also devastated by the asteroid. They all turn back to the island to see that it has been completely destroyed, the flames from the island illuminating it in an orange glow. Suri goes up to the edge of the mainland and calls out to the island, trying to hear if anyone on the island survived, but she gets no response. Suri weeps as she realizes that everyone on the island is gone, and Aladar bellows a similar mournful roar. Pilo comforts her daughter until Aladar tells them that they cannot stay where they are. With that, they all climb onto Aladar, who looks one last time at the island that was once his and his family's home, before turning around and walking off.