The story:
When a warrior encounters a giant ???dragon?? in a taboo swamp, his grandfather cannot investigate the matter, but asks the Phantom for advice. After entering the swamp to verify the fantastic claim, the Phantom is baffled to see that a stegosaurus has survived the Ice Age and hatched in the jungle.

When several efforts to imprison "Stegy" prove fruitless, the Phantom reverts to a more trusted method of his: taming the animal, which is easier said than done, as is the gargantuan task of persuading palaeontologists, museum directors and even newspaper editors that such an ???extinct?? animal exists.