A shipload of passengers aboard a spacecraft are forced to crash land on a primitive planet. In fact, it very much resembles earth from 100 million years ago, complete with an assortment of stop-motion-animation dinosaurs. They crash in a lake, one of the women is eaten by a small mososaur and so they continue to find a safer place to make camp, encountering stegosaurs, horned dinosaurs and eventually a mean T-Rex that they have to kill. Along the way most of them perish, primarily as dinosaur food.
This is an extremely ambitious movie for the time in which it was created. The acting is pretty stiff, along the lines of a film student short, but the locations and effects more than make up for this. Highly recommended.