Accompanied by both professional palaeontologists and amateur enthusiasts, David Attenborough returns to the quarries where he hunted for fossils as a boy, and visits fossil-rich sites all over the world. He looks at the problems associated with reconstructing an animal from a fossil, and explains the huge role now played by animations, computer graphics and articulated models. Dramatic dinosaur finds shed light not only on how these incredible creatures looked, but how they fed, hunted, courted, bred, called to each other and cared for their young. The biggest dinosaur question, of course, remains unanswered - David Attenborough asks why, after dominating the planet for over 160 million years, the dinosaurs became extinct? From landscapes covered in shards of dinosaur egg shell, to sites where animals and plants have been fossilised to give a detailed picture of the whole environment, David Attenborough travels the world opening windows onto worlds and lives that would otherwise be lost for good.