Late Triassic Segment (220 Million Years Ago): The program starts in the Late Triassic, near modern-day New York City. The narrator explains how the Permian mass extinction led to new forms of life, including, eventually, the dinosaurs. The camera tracks a Coelophysis through the woods. The program decipts Coelophysis as preying mainly on small animals, such as insects and Icarosaurus. It encounters other, larger non-dinosaurs such as Rutiodon, Traversodon, and Desmatosuchus. Nevertheless, the quick Coelophysis is a very successful inhabitant of this world. Early Jurassic Segment (190 Million Years Ago): The program moves on to the Early Jurassic of Pennsylvania, showing a pack of Syntarsus. These dinosaurs, closely related to Coelophysis, are hunting for the primitive herbivorous dinosaur Anchisaurus, only to be driven away by a Dilophosaurus, which kills and eats the Anchisaurus. Late Jurassic Segment (150 Million Years Ago): The show skips to the Late Jurassic, where a pterosaur soars while a Ceratosaurus chases a Dryosaurus and its two young. The Ceratosaurus catches one of the juveniles, while the other Dryosaurus escape to the cover of a herd of Camarasaurus, feeding on the sauropods\' conifer tree scraps that fall to the ground. The Ceratosaurus disturbs a Stegosaurus and gets whipped by its tail. Two Stegosaurus eventually mate. As the rainy season comes, a herd of Apatosaurus arrive, followed by a hungry Allosaurus. The Allosaurus cannot get past the Apatosaurus\'s whipping tails, but it manages to catch and eat the Ceratosaurus, still pursuing the Dryosaurus. Later, as the Apatosaurus leave the area, one Apatosaurus stumbles. Disabled, it is an easy meal for a small group of Allosaurus.

Middle Cretaceous Segment (90 Million Years Ago): The program then shows a New Mexico forest of the Middle Cretaceous. Some coelurosaurs scamper through the forest, among frilled and feathered dinosaurs. One lone dromaeosaur [3] tries to attack a Nothronychus, only to be slashed by its long claws. An old male Zuniceratops is attacked by the pack of dromaeosaurs and is fatally wounded. Just as it is time to finish off the old Zuniceratops, a forest fire springs up, and most of the dinosaurs escape in all directions. However, the feasting dromaeosaurs are too distracted and become trapped in the fire. Late Cretaceous Segment (65 Million Years Ago): The program explains that dinosaurs similar to Zuniceratops evolved into the famous Triceratops. In the Late Cretaceous, Anatotitan and Triceratops graze, while ornithomimids peck at small animals in the grasses. Quetzalcoatlus soar overhead, looking for carcasses. A young Tyrannosaurus arrives on the scene, and the Triceratops form a defensive circle. Unable to get past the horns of the Triceratops, the Tyrannosaurus attacks a Quetzalcoatlus, which flies away from the potential danger. The next day, the young Tyrannosaurus and its siblings are taught by their mother to hunt. They target an Anatotitan, with the young scaring it into the mother\'s trap. The Tyrannosaurus kill the Anatotitan, but before they can eat, an asteroid slams into earth, rendering all dinosaurs extinct. Out of the ashes, several Purgatorius emerge, and the narrator explains that small mammals such as these will eventually evolve into humans.