The story begins in 220 million years BC when ancient reptiles ruled a land dominated by desert. One group of reptiles in particular is about to take over the world.

This is the story of one of the largest animals to walk the Earth - the mighty, long-necked Sauropod. Growing to a size of 30 tonnes, these creatures' constant grazing helped to shape the Jurassic landscape.

149 million years ago, Oxfordshire was almost entirely submerged in an ocean world, ruled not by dinosaurs but by marine reptiles. This is the story of the violent struggle for life here, as hundreds of Ophthalmosaurus come into the shallows to give birth, attracting predators like the Liopleurodon, the biggest of all the carnivores.

The skies of 127 million years ago were dominated by huge flying reptiles, some as large as aeroplanes. We follow an extraordinary journey undertaken by a Pterosaur. Flying for thousands of miles over continents and oceans to reach his breeding grounds, for this ageing giant of the sky, the journey is his last.

100 million years ago Antarctica was covered in trees. For half the year the dinosaurs basked in 24 hour sunshine but the other half was a long winter of freezing twilight. A group of delicate plant-eating dinosaurs called Leaellynasaura struggle to survive these seasons of extremes, and to stay one step ahead of the polar predators.

It is 65 million years ago, and as the Cretaceous period draws to a close, the world is poisoned by massive volcanic activity. A mighty Tyrannosaurus battles to rear her young, but her efforts are in vain. A giant comet heading for Earth is destined to mark the end of the age of the dinosaurs and to transform life on earth forever.