Anyway, this is a sort of Frank Frazetta inspired At the Earth's Core mashup. It's a book by Edgar Rice Burroughs and a film from the 70s (which the title is a quote from). The pterosaur guys (Mahars) were guys in suits in the film and look nothing like this. Still think the film is great and I have a DVD signed by one of the actors (Caroline Munro). I thought I'd better add a knife in the girl's hand, adds something and makes her look a little less helpless.
