The Pteranodon family goes under the sea again, to ride the Dinosaur Train Submarine - this time they go to meet Shoshana Shonisaurus, an enormous marine reptile that's something between a dolphin and a whale. Since Shoshana loves to dive down very deep, Shiny has a problem with following her down to the bottom of the sea. Shoshana kindly helps Shiny get over her fear of diving deep. When Buddy expresses his feelings about being adopted to Tiny and Mrs. Pteranodon, they tell him that he will always be a part of the Pteranodon family. Mom takes Buddy and Tiny to meet another adopted dinosaur kid named Sonny Sauroposeidon, a huge tall creature, now a part of tiny Mikey Microraptor's family. Buddy and Sonny bond over being adopted and knowing that they are both in adoptive families that are different species but still love and appreciate them.
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