Creatures the World Forgot (1971)

As the first nomadic tribes wander across the vast wilderness of the infant planet they confront hostilities created by the harsh environment and each other. After a massive volcanic eruption a tribal chief is killed and his two sons fight for supremacy, not only for the leadership of the tribe but also for the love of a beautiful young woman. The age-old battlegrounds of rivalry, envy and passion are explored in this tale of prehistoric adventure.