Planet Dinosaur

The third episode looks at the last generation of killer dinosaurs - carnivores that took killing to a new level.

By the end of the Cretaceous period - 75 million years ago - these gigantic and specialised hunter-killers had spread throughout the globe. In the southern continents, it was the powerful and muscular abelisaurids that reigned supreme, but it was the famous tyrannosaurids (or tyrant dinosaurs) that dominated in the north.

Whilst the northern daspletosaurus hunted in gangs, using its highly developed smell and hearing to take down opponents like the horned rhino-sized beast chasmosaurus, in the southern hemisphere the small-skulled majungasaurus reigned. And though the sharp-toothed majungasaurus was an efficient killer of the much smaller feathered rahonavis, that did not stop it from occasionally turning cannibal and hunting its own.

This episode focuses on the Jurassic period, a time when the first giant killers stalked the Earth and lurked in the seas - and the slightest advantage meant the difference between life and death.

In North America, the iconic allosaurus, an ambush hunter with a lethal bite, dominated. Not even the heavily armoured stegosaurus was safe from this killer, and incredible evidence reveals a glimpse of a vicious battle between these two giants.

Life in Jurassic oceans was no easier - in 2008, a fossil was dug out of a frozen island high in the Arctic. It was a colossal marine reptile, twice as big as most ocean predators at 15 metres long and weighing about 45 tonnes. This was Predator X. Its skull alone was nearly twice the size of a Tyrannosaurus rex's, and its bite force unmatched by anything in the Jurassic seas.

The balance of power between predator and prey is a fine one, as prey continually evolve different ways to avoid predators. But for the most successful and enduring predators, the battle to survive has always been tipped in their favour.

This episode focuses on the new giants, the heavyweights of the dinosaur world. It is only in recent years that experts have unearthed the biggest dinosaurs that ever lived.

One monster, the immense argentinosaurus, eclipsed all others, being more than seven times as heavy as the diplodocus. A single backbone was bigger than a human.

For years, these giants were considered immune to attack from any predator - until the discovery of the mapusaurus, a new giant killer whose fate appeared to be inextricably linked to the argentinosaurus.

The final episode explores dinosaurs' extraordinary ability to survive. Featured dinosaurs include the bizarre magyarosaurus, which lived in the shadow of the biggest flying animal - hatzegopteryx - and showed an amazing adaptation to island life; and the weird nothronychus, a carnivore that gave up meat eating.

This astonishing capacity to evolve into ever more diverse and bizarre forms meant that dinosaurs not only spread throughout the world, but also dominated life upon it for more than 160 million years. It was only an unprecedented extraterrestrial event that finally saw the end of planet dinosaur.