152 million years ago, Late Jurassic (Colorado)Filming location: California State Parks, Chile, Tasmania, New Zealand

This episode follows the life of a young female herbivorous sauropod Diplodocus beginning at the moment when her mother lays a clutch of eggs at the edge of a conifer forest. Months later, some of the eggs hatch and the young sauropods are preyed upon by Ornitholestes. After hatching, the young female and her siblings retreat to the safety of the denser trees. As they grow, they face many dangers, including repeated predation by Ornitholestes and Allosaurus. Even the herbivorous Stegosaurus accidentally kills one of her siblings while swinging its tail.

In parallel, adult herds of Diplodocus are depicted as titanic eating machines that use their massive weight to topple trees in order to get at the leaves of cycads in between trunks. The Diplodocus are also shown to host their own small mobile habitats that include damselflies, Anurognathus and dung beetles.

Close to adulthood, the creche of five-year-old Diplodocus grow to 13 meters and are nearly all killed by a huge forest fire (made worse by a firestorm in the night). In the end only three, then two, survivors including the female make it onto the open plains, where they encounter several Brachiosaurus · , before finding an adult Diplodocus herd and safety. Years later, the protagonist female mates, but not long afterwards is attacked by a bull Allosaurus. She is saved when another Diplodocus strikes the Allosaurus with its tail. She rejoins the herd but with a deep wound. In the end it is commented that her kind will only get bigger and that when the sauropods die out, life will never again be this large. In the DVD release, most of the narration from the original broadcast is missing.

Animals Diplodocus · Allosaurus · Ornitholestes · Stegosaurus · Brachiosaurus · Anurognathus · Dryosaurus · Othnielia · Dung Beetle

127 million years ago, Early Cretaceous (Brazil, North America, Europe and Cantabria)
Filming location: New Zealand, Tasmania

The story begins with a male Tropeognathus (identified simply as Ornithocheirus) dead on a beach. It then goes back six months to Brazil, where the Tropeognathus, resting among a colony of breeding Tapejara flies off for Cantabria where he too must mate. He flies past amigrating column of iguanodont Dakotadon and a Polacanthus (all herbivorous dinosaurs). He reaches the southern tip of North America, where he is forced to shelter from a storm. To pass the time, he grooms himself, expelling his body of Saurophthirus fleas while his beak's display crest begins to show color changes in readiness for mating. He then sets off across the Atlantic(which was then only 300 kilometers wide) and after a whole day on the wing, reaches the westernmost of the European islands. He does not rest there however, as a pack ofUtahraptors are hunting Iguanodon - one attack fails, but another assault succeeds and a young Utahraptor is bullied off the carcass by the adults after trying its luck. The Tropeognathus flies to the outskirts of a forest to rest, but is driven away by Iberomesornis birds. Flying on, he reaches Cantabria, but due to the delays and his exhaustion he cannot reach the center of the many grounded male Tropeognathus and consequently he does not mate. After days under the sun trying to attract a mate, the protagonist Tropeognathus dies from heat exhaustion and starvation alongside others who also lost out. Nature however is seldom wasteful, their corpses are yielded as food by the next generation.

Animals Tropeognathus (identified as Ornithocheirus) · Utahraptor · Dakotadon (identified as North American Iguanodon) ·Iguanodon · Tapejara · Polacanthus · Iberomesornis (identified as bird) · Plesiopleurodon (unidentified) · Saurophthirus · unidentified crested Pterosaurs · Fish