The Missing Link

A group of cavemen emerges from the mud and quickly begins scavenging and hunting to survive. After two failed attempts to find food, they resort to cannibalism, killing one of their own for nourishment. This brutal start sets the tone for their harsh early world.

Nine months after the cannibalism incident, a woman gives birth to two boys, Ah and O. The elders favor Ah and treat O with suspicion, eventually abandoning him. The brothers' fragile family dynamics shape the tribe's future.

The elder witnesses a pair of stegosaurus mating and imitates the act with a woman. The group grows attached to Ah while fearing O, who is effectively cast out. O soon befriends Igua, a baby brontosaurus, and they become inseparable.

Igua finds an abandoned egg that hatches into Croak, a baby pterodactyl. O and Croak become friends, and Croak tries to help O become smarter. Their first lesson is flight, but Igua intervenes and separates them.

O looks into a pool and sees his reflection, realizing he is a man, not a brontosaurus. He leaves Igua and embarks on a quest to find his own kind. This marks the start of his lone journey through a dangerous, strange world.

During his travels, O mistakes several creatures for humans, including a wild boar and a giant worm. He wanders through a perilous jungle and nearly falls victim to a menagerie of creatures at night. Eventually, Croak finds him again and they fly away together until Croak crashes, separating them.

Igua finds a nearby lake with other brontosauruses but is shunned because he smells like 'man.' He is crushed by this rejection and resolves to find O again. This sets up the parallel quest back to O.

O meets the workaholic creatures known as the No-Lobes and causes chaos that leads to a pivotal invention: the wheel. His mischief destroys their crops, prompting his expulsion and escalating his search for humanity. The wheel's discovery foreshadows mankind's ingenuity.

A feline seductress named No-Man lures O with her tail and drags him toward her tribe. A newborn distracts the tribe, enabling O and No-Man to escape together, but No-Man's tail is later cut off in a stampede of giant turtles. O escapes into the desert, leaving No-Man behind.

O reunites with Croak while seeking water and encounters a dragon. He helps the dragon by inserting a cork into its anus to trigger a fire-breathing moment, and the dragon grants him water before the hole proves to be a tar pit. The dragon then ferries O to a lake.

O reaches the Arctic and meets a group of Norwegian barbarians who marvel at fire. Their use of fire melts their coats and drains their world; Croak saves him as the group sinks, and O is eaten by a shark but escapes. He continues his search for his human family.

O finally returns to his human family and is recognized, though the elder dies soon after. O takes on a leadership role and vows to teach humanity what he has learned on his travels. Igua finally catches up with O, and the two reconcile.

Ah rises as a leader and shoves O into a fire to demonstrate power. Igua saves him, and O and Igua reconcile their friendship. The internal tension highlights competing visions for the tribe's future.

Ah's faction reshapes the Earth in their image, wiping out the dragon and exterminating the No-Lobes. The dinosaurs drive themselves to extinction by mass suicide, and the feline clan is slaughtered for clothing, save for No-Man who later dumps O. An ant-rocket ends in disaster, and Pangaea splits into continents.

O, Croak, and Igua escape the devastation and settle on a deserted island. O accepts the title of the missing link and reflects on the consequences of his actions. The trio remains together as the world changes around them.