The Pteranodon family sends Buddy on the Dinosaur Train so he can join Annie, Deloris, and Boris Tyrannosaurus for a week on their migration, traveling with the T. rex pack as they follow a herd of giant sauropods across the plains of Laramidia. As Buddy travels with Annie's family, he gets to experience being a T. rex more than he's ever done. During the migration, Buddy deals with several `firsts': being away from home alone for the first time, being with another family, being on the move every day, and being homesick. Buddy and Annie bond more as they make it through the week. By the end of the week, Buddy is more adapted and glad that he experienced T. rex life a little more than he's ever done before. But he's really happy to come back to his adopted family, and has a new appreciation for them. / When Mrs. Pteranodon overhears Buddy telling his siblings what a great time he had on migration, she gets the idea to create a Pretend Migration for the kids. Tiny, Shiny, Don, and Buddy must use their senses and follow the clues to their surprise dinner at the Big Pond!