As seen by little Dip (that's short for diplodocus), a large silver round thing lands in Dinosaur Valley, lots of little two-legged things come out of it (""Welcome to our first stop on the Back Into Time Tour,"" says one), and while the others go off to look at plants, one of them, a Harold thing, takes out a little square thing that lights up like the moon and watches some very tiny moving things inside of it. The Harold thing calls the light-like-the-moon thing a World Series, and in it the tiny moving Giant things are throwing rocks and hitting them with sticks. Well, that gives Dip the idea of throwing rocks too, grasping them in his mouth and winding up with his neck. He teaches his parents to do the same--and guess what happens when the terrible Tyrannosaurus Rex comes roaring along? It's the sort of humor you find on the Saturday morning light-like-the-moon thing, with only Simont's agile rock-throwing dinosaurs to compensate for TV's special effects.