Doraemon the Movie: Nobita and the Knights on Dinosaurs

Synopsis

Doraemon creates a secret hideout for his friends deep inside an underground cavern. During their exploration, Suneo goes missing, and the rest of the group manages to leave the cave without him. Realizing Suneo is gone and finding the entrance blocked, they search for another route back into the cave system, only to end up in a world inhabited by dinosaurs. There, a warrior named Vanho rescues them and claims to have located Suneo. After being reunited, they learn Vanho's true intentions: his people intend to study them as human specimens and eventually conquer the Earth's surface.