Littlefoot, Tino, Doraemon, Thomas the Tank Engine, Twilight Sparkle, and their friends are constantly being bullied and browbeaten by three teenage dinosaurs: Hyp, a Camptosaurus; Nod, a Gastonia; and Mutt, a Hadrosaurus. However, when a shower of meteorites impacts near the Great Valley and causes a rock slide in the Mysterious Beyond, which blocks the water supply of the Great Valley, Hyp, Nod, and Mutt are no longer the biggest worry of Littlefoot and his friends. The increasing lack of water causes conflicts between the inhabitants of the Great Valley, who have lived in relative peace and harmony until this event.
When the interspecies situation becomes worse and worse, Littlefoot and the others set out to find water, whereby to keep the peace in the Great Valley. They are pursued by Hyp and his cohorts. When Littlefoot and the others find a small lake, the teenagers emerge and claim the waterhole for themselves, demanding that Littlefoot and the others keep silent about their discovery. Unwilling to comply, Littlefoot and the others flee from the bullies and during the following pursuit discover the reason for the blockage of the Great Valley’s water source.
Before they can return and tell the other Valley inhabitants the truth, a lightning strike ignites a wildfire that spreads rapidly through the dried Valley. The dinosaurs barely make it to safety at the edge of the Mysterious Beyond while the fire ravages their home. When the protagonists tell the other dinosaurs of their discovery of the water's being blocked in the Mysterious Beyond by the rock slide, disunity about what to do prevents the adult dinosaurs from doing anything to utilize this knowledge. Hyp, Mutt, and Nod set out into the Mysterious Beyond on their own to get to the water first.
Anticipating the danger to which Hyp and his cohorts have exposed themselves, and recognizing commonality with them, Littlefoot and the others follow them, in order to help if necessary. It becomes necessary when a pool of water Hyp enters turns out to be a dangerous tar pit. Littlefoot and the others pull him out of the tar by combined effort. Soon afterwards, the adult dinosaurs appear in search of their offspring and are united by the understanding that it was the unity of their children that helped them to find water. It is implied during the discussion thereof that Hyp's own experience of harsh treatment by his father is the cause of his harshness toward others, and implied later that being treated kindly improves the temperaments of Hyp and his sidekicks.
Before they are able to take further steps, the herd is attacked by a pack of four Sharpteeth Velociraptors. These carnivores are portrayed as small, vicious antagonists who have a reddish skin with black stripes and act with a bandit-like unity. The following pursuit leads to the bed of the now dry river that flows through the Great Valley and exactly to the spot where a dam of boulders created by the rockslide has blocked the river. During the following encounter between the sharpteeth and the herbivorous dinosaurs, the unity of the children — a group which now includes Hyp and his cronies — proves elemental. Cera's father, Littlefoot's grandfather, and later Hyp's father keep the sharpteeth occupied while Cera and the now placid teenagers succeed in breaking the dam. They all watch as the freed water washes away the sharpteeth (though they manage to survive and land on the opposite bank).
The herbivores return to the Valley, which now has enough water for them, although the fire has destroyed most of the plants on which they feed. Working together, the dinosaurs survive the time until the plants start to grow again by feeding on the last remains of the plants, moving from one verdant area to another and sharing everything they find; a behavior which gives this time its name “The Time of the Great Giving”.
- Doraemon, Noby, Sue, Sneech, Big G, Twilight Sparkle, Applejack, Rarity, Rainbow Dash, Pinkie Pie, Fluttershy, Spike (MLP), The Cutie Mark Crusaders (Apple Bloom, Sweetie Bell, and Scootaloo), Thomas, and Percy guest stars in this film.