While riding the Dinosaur Train with Buddy and Mom, Tiny gets the idea to gather all the dinosaurs in the "Dinosaurs A to Z" song for a picnic at Troodon Town. The Conductor agrees, and as the Train starts picking up dinosaurs, Tiny, Buddy, Shiny and Don help keep track of how many of the different species have come on board. They learn about classification and organize the dinosaurs by their species, features, and size. When all 26 dinosaurs finally come on board, the Train has more extra cars than it ever has -- and they need an additional engine to help pull it! Once they arrive at Troodon Town for the picnic, Tiny leads the 26 different "A to Z" dinosaurs in a fun, rousing, and historic singing of the "Dinosaurs A to Z" song!