Dinosaur tells the tale of an ambitious dinosaur named Aladar (voiced by D.B. Sweeney) who is plucked out of his mother's nest and carried off to some unsuspecting primates. As he grows he accepts the frisky primates as his family. Just as the yearly mating ritual begins, Aladar's surroundings are engulfed in a cosmic event forcing Aladar to scoop up his adopted family and flee the safety of their island. Returning to the real world proves a challenge for Aladar and his adopted primate family as they try so hard to fit in with a huge migrating herd.