Set in the prehistoric past when humans and dinosaurs lived together (yes, I know!) and the moon had not yet formed (yes, I know, I know!) a small tribe is struggling to survive by giving a sacrifice of a blonde woman to their god, the sun, in return for protection from the giant lizards and other creatures that prey on them.
Cavegirl Sanna (Victoria Vetri), one of the sacrificial offerings, finds herself on her own when a freak storm interrupts the ceremony. As she searches for a safe haven she encounters hostility from rival tribes and lots of huge and deadly dinosaurs.
Sanna ends up with another tribe who are suspicious of her; all except Tara (Robin Hawdon), a hunky cave chap who takes a shine to the new arrival. However, Ayak (Imogen Hassall) is jealous and does her best to get the rest of them to gang up on Sanna, which results in our heroine making a break for it.
But Tara does not forget her and goes searching while she ventures out alone, almost getting eaten by a large, carnivorous plant for her trouble.
Sanna’s love story ends up almost displaced by an adoption plot where after she wakes up in a large eggshell and a mother dinosaur thinks that she’s her offspring (and Sanna gets to frolic with a baby dino in endearingly ridiculous sequences).
She also displays a talent for fishing, at one point diving into a pool and surfacing with a fish in her teeth.
When Dinosaurs Ruled the Earth is utterly unhistorical, with the Moon being formed at the same time as the dinosaurs who share the planet with humans, but as fantasy goes it’s amusing enough for a film where you have no idea what the actors are saying for the whole time.
The other selling point had been Ray Harryhausen’s stop motion effects that brought the creatures to life, but he was not available for the follow-up, When Dinosaurs Ruled the Earth, so Jim Danforth was brought in.
Also not returning was Welch, so an alternative was brought to the table: former Playboy Playmate of the Year Vetri, who was guaranteed to look her best in that cavegirl attire.
Although the film was completed in 1968, Danforth’s special effects weren’t ready and the film premiered in 1970.