Monster from a Prehistoric Planet is the English dub title for Daikyoju Gappa (Shochiku, 1967).

"Monster" should've been plural since there are three, & there is no prehistoric planet involved since the Gappas come from inside a mountain on a south seas island. The old video tape release title was an improvement for accuracy, Gappa the Triphibian Monsters.

An investor is developing an amusement park that will allow tourists to experience a South Seas tropical paradise without travelling outside of Japan.

He sends explorers by sea into Polynesia to find rare wild animals that can be safely turned loose in his the "natural" zoo park he has planned.

What they bring back instead is a baby Gappa they saw hatch from a giant egg in a cavern by an underground lake of a volcanic island. The natives of this island worshipped these creatures without troubling event, but when modern exploitation inserts itself, expect havoc.

When the parents of the baby gappa rise up out of the subterranean lake, they find their egg hatched but no baby. They set out to destroy the nearby Polynesian village, though they had lived for centuries near this population without injury to one another.

Gappas look a bit like Godzilla hybridized with a chicken. They have parrot beaks & wings, & the male has a big bony crest on his head. They are "triphibioius" because they can live in the sky, under water, or on land.

The parents after trampling the local village unfold their stubby wings, become magically weightless, & fly away over the sea after the scent of their stolen baby, straight for that popular monster-magnet, Japan.

Meanwhile one of the boys from Polynesia, a wee Japanese lad in blackface, tries to convince the investor & the professor (who argue over who owns the baby gappa) to return the baby to its parents before there is trouble.

The boy & also the leading lady apparently have some kind of ability to communicate emotionally with the baby gappa, an element left undeveloped but useful in conveying to child viewers that the gappas aren't really horrible, they're just big.

The gappa parents show up & there are extended scenes of the rubber suit critters stomping on models, including a beautifully constructed model of a medieval castle.

The creatures prove themselves impervious to weapons, & when they're sufficiently annoyed, the plast the army tanks & jet bombers with their heat-ray death-breath.

Finally someone listens to the boy-in-blackface & transports the baby gappa to where the parents have been stomping on stuff. The reunited family hugs one another then flies away back to their island home.

In the film's coda we are provided with lessons & morals about family devotion which the gappas represented. Indeed, the film's leading lady announces she must finally now do the right thing. "I will quit my job, marry an office worker, & wash diapers."

Hard to believe such low grade sci-fi served as theatrical releases rather than Saturday morning live-action substitute for Tobor the Eight Man cartoons. Apart from the questionable moral lesson at the end, however, it's a serviceable kiddy flick.

For more prehistoric survival films, see:
Three films about the Loch Ness Monster

copyright © by Paghat the Ratgirl