One fateful night they are summoned by an unknown alien intelligence who tells them that mankind is losing its empathy, and, to teach them a lesson about life, death, and the fall of species, said alien intelligence transports the kids to Earth's past and leaves them right in the Mesozoic era, the time when dinosaurs were the supreme rulers of the Earth. Here, the trio has a series of adventures and misadventures, like befriending a baby Triceratops, trying to escape from a dangerous Tyrannosaurus rex, witnessing the Cretaceous extinction and rise of the mammals, and discovering why it is important for humans to protect Earth before it's too late.
As mentioned above, the film is very poorly-known, and only a few home releases are known. It can be watched for free online, but is usually found in a foreign language, like Spanish.
- Alas, Poor Villain: The Tyrannosaurus eventually gets speared to death by the cavemen, though this becomes sorrowful considering it's the Last of Its Kind.
- All Animals Are Dogs: The Triceratops hatchlings utter puppy-like squeals and coos.
- Anachronism Stew: Despite being set in the Cretaceous, dinosaurs and other reptiles from the Triassic and Jurassic periods appear as well. The most jarring example is the cameo of the pelycosaurian synapsid Edaphosaurus, which was already extinct by the time the earliest dinosaurs showed up. And then there's the Ice Age occurring right at the beginning of the Cenozoic era, rather than millions of years later in the Pleistocene.
- An Aesop: A green one, to be exact. Mankind must learn to take good care of Earth and use its natural resources with balance, for no species lasts forever.
- Art Shift: The film starts with live-action scenes of modern Japan with anime-drawn pictures of dinosaurs constantly popping up, then switches to animation. At the end, there's a showcase of dinosaur skeletons exposed in museums to symbolize their ultimate downfall.
- Big Bad: The Tyrannosaurus that constantly harasses the group.
- Cargo Cult: The primitive cavemen worship the Tyrannosaurus as a deity and make offerings of human sacrifices to it. It takes Chobi standing up to it to finally convince them to try fighting back against the T. rex. It's not unlike O-D-O from the prehistoric chapter of Live A Live.
- Dub Name Change: The Triceratops hatchling befriended by the kids is named "Zhu" in both the original and most dubbed releases, but the Mexican Spanish version changes his name to "Papapulis" and the English version calls him "Babypuss".
- Dumb Dinos: Averted, which is commendable as the anime was made recently after the Dinosaur Renaissance had set off. Zhu the Triceratops shows awareness of his surroundings and deliberately sacrifices himself to keep the Tyrannosaurus away from the humans. Unfortunately, the main Tyrannosaurus villain also has signs of intelligence despite being a bloodthirsty predator, as it chases after the heroes out of vengeance. The other dinosaurs don't seem to be particularly dumb (they even, quite humorously, react painfully to a battle between two male Pachycephalosaurus).
- Expy: Remi bears a strong resemblance to Francoise Arnoul from Cyborg 009.
- Eye Scream: Chobi throws a sharpened stick into the Tyrannosaurus's left eye, gouging it out. At the end of the film, as the cavemen spear the T. rex to death, one of the spears strikes and destroys his only remaining eye.
- Family-Unfriendly Violence: This is a very graphic animated film, considering its target audience. The Tyrannosaurus gets gored repeatedly, and several other dinosaurs, including babies, fall to his appetite.
- Headbutting Pachy: A pair of of pachycephalosaurus are shown to be headbutting each other so hard that it not only gets the attention of other dinosaurs, but scares them too. Not the Tyrannosaurus rex though, he came for dinner.
- Heroic Sacrifice: The friendly Triceratops pushes the T. rex over a cliff, deliberately plummeting down with it, to keep him away from the humans.
- Last of His Kind: The Tyrannosaurus is this by the end.
- Mama Bear: The mother Triceratops fights the Tyrannosaurus for attacking her last remaining young. Sadly, she doesn't win.
- Non-Human Sidekick: The baby Triceratops Chobi befriends, imprinting on them as its parents. Its brothers and sisters did the same, but the Tyrannosaurus has other ideas...
- Ptero Soarer: The Pteranodon in this movie are bipedal and have teeth, though they at least feed on fish and pick them up with their beaks. The Rhamphorhynchus, however, are relatively accurate for the time.
- Seldom-Seen Species: Eusthenopteron, Eryops, Placochelys, Clidastes, Edaphosaurus, Scolosaurus, Henodus, Acanthopholis, Deltatheridium, Pliohippus, Australopithecus, Homo habilis, Homo erectus, Moeritherium, and Tetralophodon make appearances in the film. Character sheets show there were plans to include Ornithosuchus, coelacanths, and Nothosaurus.
- Stock Dinosaurs: The film features ammonites, trilobites, Dunkleosteus, Meganeura, Tylosaurus, Elasmosaurus, Pteranodon, Ornitholestes, Triceratops, Tyrannosaurus rex, Rhamphorhynchus, Plesiosaurus, Brontosaurus, Stegosaurus, Ankylosaurusnote , Corythosaurus, Brachiosaurus, Protoceratops, Iguanodon, Edmontosaurus/Trachodon, Pachycephalosaurus, Camptosaurusnote , Struthiomimus, Gorgosaurus, Smilodon, and woolly mammoths. Cut animals include Archelon, Allosaurus, and Ichthyosaurus, although Ichthyosaurus does appear in one of the anime-drawn pictures of prehistoric animals in the opening.
- Super-Persistent Predator: The T. rex shows up everywhere the trio go, even somehow travelling through time all the way to the Stone Age. It's actually pursuing them to get revenge, as they had taken out its eye and their Triceratops friend nearly killed it.
- Twinkle in the Eye: The Tyrannosaurus does this frequently.
- Tyrannosaurus rex: The film's main antagonist.