The kids are turning their classroom into Dinosaur Land for Parents Night, as they are studying dinosaurs. Ms Frizzle then gets a letter from an old high school friend who is now a paleontologist and she decides to take the class on a trip to the dig. When she discovers that they are missing the bones of some Maiasaurs, she turns the bus into a time machine to travel back to the age of dinosaurs to find the bones. The class sees dinosaurs and learns the name of the different periods of the era and other information.
- This book is the first time Ms. Frizzle's first name is mentioned.
- This the first appearance of Keesha and Carlos in the book series, the TV series debuting the same year this book was released.
- The book seems to feature a predestination paradox. In the present, the palaeontologists find Maiasaura bones, but have difficulty finding their nests. An astute reader will notice that the Maiasaurs were apparently separated from their nests because of the Troodon pack the class inadvertently led to their nesting grounds.
The episode's main aim was to show that dinosaurs weren't all terrifying monsters, like movies often make them out to be. The only period seen is the Cretaceous Period (all periods are visited in the book), which was obviously due to time constraints. In this episode, the kids visit Ms. Frizzle's old friend, Dr. Carmina Skeledon at a dinosaur dig, as opposed to Jeff in the book. Dr. Skeledon lets Arnold see a fossilized dinosaur egg that Ms. Frizzle finds as the kids are leaving, and he still has it when they go back in time. The kids watch as they entered the Ice Age and finally end in the Cretaceous. Having gone back "67 million years, give or take a month or two", as Ms. Frizzle tells them, the kids are frightened away by the appearance of large, long necked dinosaurs called Alamosaurus.
They separated and scattered, Arnold running to Phoebe and Liz. He trips on a rock, and the egg went flying, Liz catching it in time. Arnold lets Phoebe see the egg, but an Ornithomimus steals it from her. Arnold runs after the dinosaur, yelling "That egg doesn't belong to you! Come to think of it...it doesn't belong to me either!" Phoebe runs after him, Liz quickly running to tell Ms. Frizzle.
The rest of the class and Ms. Frizzle re-group, Liz explaining that Arnold and Phoebe ran off. Carlos, being paranoid about getting eaten by dinosaurs exclaims, "I knew this would happen! The dinos did them in!" The class hides out on a river bank, looking out for Arnold and Phoebe, and Ralphie spots them. They cross a herd of Parasaurolophus and land in a Maiasaura nest. The class continues on their way, only to find themselves with a Triceratops herd in a field. A pack of carnivorous Troodon chase a baby Triceratops, and the smaller Troodon are scared off by the larger Triceratops.
Meanwhile, Arnold and Phoebe chase the Ornithomimus. It sniffs the air, and it drops the egg when it realizes a sleeping Tyrannosaurus is near by. Arnold and Phoebe are unaware, and as they look, Arnold finds the egg near a large "rock". Phoebe helps him pull it free saying, "Something tells me we shouldn't be here". As Arnold asks, "Like what?", they wake the T-Rex and Phoebe exclaims, "Like that!" The two run as the T-Rex chases them, and they find themselves in the same field as the class. Arnold trips into a mud puddle, losing the egg, and he hides under the bus as Phoebe runs back on. Ms. Frizzle grows Arnold as the T-Rex attacks the bus, and he scares it away, the class learning that the carnivore only wanted "an easy meal without a fight". In the future at the dig site they find a fossilized foot print of giant Arnold's sneaker. "Possibly from a sneakersaurus".
- Dinosaurs featured:
*Alamosaurus : Plants *Parasaurolophus : Plants *Maiasaura : Plants *Triceratops : Plants *Ornithomimus : Meat (Meat and plants in real life) *Troodon : Meat *Tyrannosaurus : Meat
- First and only time travel field trip
- Arnold acts courageously, rather than being unsteady and cowardly.
- Phoebe does not say "At my old school..." Instead she somewhat uses Arnold's catchphrase and says, "It's a good thing you didn't stay home today, Arnold!"
- The dinosaur egg Arnold takes back in time is "unfossilized." Logically, since Ms. Frizzle and the kids weren't "unborn," the egg should have stayed fossilized.
- In the Parasaurolophus scene, the "screen" behind the crest of the dinosaur changed color. The is NO evidence to back this up. Also, they stood bipedally, were they only walked like that when in danger.
- The Troodon were shown walking flat-footed.
- The Troodon was shown without a sickle claw.
- Dr. Skeledon was played by Rita Moreno, with whom Tomlin shared the role of Violet Newstead from Nine to Five. Tomlin played Newstead in the original movie while Moreno played her in the subsequent TV series.
- Ornithomimus is more likely to be an omnivore than a true carnivore.
- Throughout the episode, the egg is shown being tossed around wildly at different points. Dinosaurs didn't turn their eggs like birds, for the embryo inside would have died.
- Tyrannosaurus was not the biggest meat-eater, either Giganotosaurus or Spinosaurus was the largest meat-eating dinosaur. (The biggest meat-eater of all time was a pliosaur named Liopleurodon).
Ms. Frizzle is missing some photographs from her photo album of her last trip to the age of dinosaurs. As usual, the user has to find replacements. There are seven different places, including "Triassic Arizona", "Triassic Argentina", "Jurassic Colorado", "Jurassic Tethys Sea", "Jurassic Tanzania", "Cretaceous Alberta", and "Cretaceous Mongolia".
Unlike the book, the Bus transforms into three different dinosaurs, some sort of prosauropod for the Triassic Period, Stegosaurus for the Jurassic Period, and Pteranodon for the Cretaceous Period.
This game has very elaborate CGI forms for the bus. Although the classroom location song has changed in the following games, the game's classroom location song is the same as The Magic School Bus Explores Inside the Earth, but had added more rhythm in between. The classroom theme song in this game was re-used in the following game, The Magic School Bus Explores the Rainforest.