Highly imaginative, well acted and taking itself very seriously, this unjustly unpopular Sci-fi stars teenage (lol) Robert Vaughn as the unnamed Symbol Maker's son (also giving the film it's dreadful title) questioning the law and custom of his primitive tribe, a group of suspiciously modern cave-dwellers in California... well it was shot there anyway. Protected by his well meaning father (Leslie Bradley giving an excellent performance), he must survive against the power-hungry Black-bearded One (Frank De Kova, giving probably the best performance).
To let you down, the film promises giant dinosaurs and weird alien-like monsters... which you kind of get once or twice. If anything, the biggest threat from beyond is a bunch of doggies.
Also, I'm not certain if some of the animal cruelty is real (the bit with the monster fight). Gah...
Besides that (and that's a big THAT), stick around for the ending for a great twist, which I won't spoil for you.
By the way, producer/director Roger Corman wanted to call the film "Land of the Prehistoric Women".