The first episode looks at how birds first took to the skies in the wake of the insects. It begins in Mexico, where Sir Attenborough observes bats being outmanoeuvred by a red-tailed hawk. Pterosaurs were the birds' forerunners, some 150 million years after dragonflies developed the means of flight, but eventually went extinct together with the dinosaurs. Birds had by then already evolved from early forms like archaeopteryx, the first creature to possess feathers. Its ancestry can be traced through reptiles, and some current species, such as the flying lizard, possibly show paths this evolution may have taken." One of the biggest birds to have ever existed was the terror bird, which proliferated after dinosaurs vanished and stood up to 2.5 metres tall. By comparison, the ostrich, while not closely related, is the largest and heaviest living bird. It was probably the evasion of predators that drove most birds into the air, so their flightless cousins evolved because they had few enemies. Accordingly, such species are more likely to be found on islands, and Sir Attenborough visits New Zealand to observe its great variety, most especially the kiwi. Also depicted is the moa, another huge creature that is now gone. The takahē is extremely rare, and high in the mountains of New Zealand, Sir Attenborough discovers one from a population of only 40 pairs. Finally, another example on the brink of extinction is the kakapo, which at one point numbered only 61 individuals. A male is heard calling — an immensely amplified deep note that can be heard at great distances from its nest.

A team of intrepid palaeontologists recently discovered a lost world of dinosaurs in the unlikeliest of places — deep in the dark, snowy wilds of northern Alaska. Surprisingly, new findings indicates that dinosaurs thrived year-round and raised their young in frigid and dark conditions in the far north of the Arctic Circle.
Rappelling down giant ice cliffs bordering the Colville River, the team wields chainsaws to extract fossils frozen into the permafrost. Newly found dinosaur tracks indicates that a wide variety of species once flourished there, including herds of duck-bills, horned herbivores, pterosaurs, a new type of velociraptor, and northern relatives of T-rex.

Pterosaur hatchlings take flight to leave their island sanctuary, but are targeted by several Shamosuchus. Several Austroraptor hunt garfish and contend for the best fishing spots. A male Beelzebufo attempts to attract a mate, but his endeavor is interrupted by a herd of Rapetosaurus. A male Pachycephalosaurus must put an upstart youngster in his place. Two Tyrannosaurus brothers hunt Edmontosaurus under the cover of darkness.

The fourth episode of the series takes you on an epic journey through time, beginning 252 million years ago, in a world devastated by the greatest mass extinction in history. Discover how, from the ashes of this cataclysm, fungi become the dominant form of life in an almost apocalyptic landscape. Witness the astonishing story of survival and adaptation of the Lystrosaurus, curious ancestors of mammals, who emerge as the unlikely heirs of the Earth and transform into the dominant creatures, only to be eventually dethroned by new giant predators like the Erythrosuchus. The documentary culminates with the impressive era of dinosaurs and how they adapted to a constantly changing world, and the reigns of the plesiosaurs and pterosaurs, rulers of the oceans and the air. Finally, learn how these titans gave way to modern reptiles and current birds, leaving a legacy that endures to this day.
This documentary is a window into the fascinating evolutionary history of our planet, showing the resilience and diversity of life through the ages. Prepare to be amazed, informed, and deeply moved by this spectacular chronicle of life on our planet.