After 160 million years of dominating life on Earth the dinosaurs appear as vigorous as ever. Tyrannosaurus rules over plains full of herds of horned and duck-billed dinosaurs. Yet closer study reveals there are hidden stresses and the rich ecosystem hides problems. Volcanic activity is high and disease and sterile eggs common. The central character in the program is a female Tyrannosaur that is trying to raise a new brood of chicks.