When Dinosaurs Ruled the Earth (titled When Dinosaurs Ruled the World in the U.K.[5]) is a 1970 British prehistoric dinosaur film written and directed by Val Guest and starring Victoria Vetri. It was produced by Aida Young. The production company was Hammer Films. The third in Hammer's "Cave Girl" series, preceded by One Million Years B.C. (1966) and Prehistoric Women (1967), it was followed by Creatures the World Forgot (1971).[6]