Doraemon Movie 08: Nobita to Ryuu no Kishi

Doraemon gives Nobita and his friends an underground hideout, but Suneo disappears inside the vast cave network and the entrance collapses behind them. Searching for another route leads the group into a hidden world inhabited by intelligent dinosaur people.

A knight named Banho helps them reunite with Suneo, yet the underground civilization has its own plans for the surface. Friendship with their rescuers becomes complicated when Nobita and the others learn that humanity itself may stand in the way of those plans.