The Pteranodon Family, with the Conductor, have raced on land a few times and in the air against Thurston Troodon, but have never raced in the water! So, after Thurston shows up in his own souped-up, "state-of-the-art" submarine, the challenge is on! Buddy, Tiny, and Mrs. Pteranodon are with Mr. Conductor in the Dinosaur Train Submarine, racing across the great Western Interior Sea against Thurston, Shiny, Don, and Mr. Pteranodon! On the way, they meet a new species of marine reptile, Leo the Liopleuridon, who helps Thurston a little too much in the race. / but he doesn't have wings like his siblings do! For 4 seasons, Buddy has run along while his siblings fly, although sometimes they carry him. When Shiny complains that Buddy is getting too big to carry around Pteranodon Terrace, Buddy feels sad for a little while, then decides to do something about it - build himself his own set of wings! Our Pteranodon kids love this, and they get to work designing and engineering, starting with funny homemade versions, a try-and-fail sequence with some hilarious crashes and some success, leading up to a cool, Leonardo-esque set of mechanical wings. The wings work! Buddy can fly with his siblings, and they have a triumphant flying session. But in the end, Buddy misses being carried. "Who am I kidding? I'm not a Pteranodon! I'm a T. rex who really loves to fly!" Buddy goes happily back to the status quo. And even better, he knows what to do with his mechanical wings - he gives them to the Pteranodon kid with a stunted wing. We end with them all flying together, the neighbor kid joyfully flying Buddy's mechanical wings.