Sir David Attenborough presents this landmark documentary which brings to life, in unprecedented detail, the lost world of the very last days of the dinosaurs. Searching in the hills of North Dakota, palaeontologist Robert DePalma makes an incredible discovery in a prehistoric graveyard known as Tanis - fossilised creatures, astonishingly well preserved like the bodies found at Pompeii.
Whilst DePalma hunts for the evidence that can shed light on the final days of the dinosaurs, state-of-the-art VFX transports Sir David back in time to the Late Cretaceous to witness the creatures who lived at Tanis at the end of the Age of Dinosaurs. Meanwhile, cutting edge scanning techniques reveal fossilised secrets that could change our understanding of the dinosaurs' extinction once and for all.

A Tyrannosaurus and two Quetzalcoatlus fight over an Alamosaurus carcass. A shoal of Sphenodiscus are ambushed by a Globidens, intent on surplus killing them. At an evaporating lake, juvenile Pectinodon hunt flies while their father hunts Styginetta. Male Triceratops fight and display for the right to mate. A female Nanuqsaurus hunts Ornithomimus to feed herself and her offpsring.

In the last episode, Austroposeidon level trees in search of fresh foliage. A herd of Triceratops journey through a cave to find an underground clay lick. A male Carnotaurus sets the stage for an extravagant display. A female Qianzhousaurus uses an autumn storm to her advantage while hunting Corythoraptor.
A family of Edmontosaurus evade a forest fire, while an Atrociraptor and Ankylosaur reap its rewards. Juvenile Therizinosaurus attempt to climb up to a bee nest. Hatzegopteryx hunts Zalmoxes, and patrols the dense undergrowth and seaspray-battered coastline.

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.