Tom and Jamie discover a prehistoric paradise and decide to explore a cave where they can swim with ichthyosaurs--dolphin-like dinosaurs--but a hungry plesiosaur adds a deadly element to their snorkeling adventure.
Tom and Jamie once again use their secret entrance to the prehistoric world to embark on another grand adventure, but instead they discover a meteorite has set the forest on fire and started a stampede that puts all their dinosaur friends in danger.
Tom and Jamie find a secret entrance to a prehistoric world, where they follow a small set of dinosaur footprints to a baby ankylosaurus that is trapped in a muddy marsh.
Tom and Jamie are thrilled after discovering a secret passage into the prehistoric world, but when a herd of triceratops comes charging, they can either grab a ride on one or get squished.