Walking with Prehistoric Beasts

For 160 million years dinosaurs have ruled the world, while mammals have lived in their shadow. Then a meteor crashes into the Earth wiping out the dinosaurs. 15 million years on, the world has changed. The sea level has risen and the temperature has reached an all time high. No animal has risen to take the place of the dinosaurs. Birds, reptiles, mammals and insects live together waiting to establish a new order. The film is about a Leptictidium, a highly successful mammal typical of this time.

The mass extinction event that saw the demise of the dinosaurs was almost as devastating in the seas. The oceans were emptied of almost all large animals and carnivorous creatures, leaving them ripe for exploitation by new predators. 30 million years after the dinosaurs, the top of the ocean food chain is now occupied by an early whale: Basilosaurus. As on land, it's the mammals that have replaced the giant reptiles as the ultimate marine predators and none can now match the Basilosaurus.

For over 40 million years forests have dominated the world. They have been the cradle of evolution for the mammals, but the world is changing. The forests are punctuated by open plains. With the constraints of living in the forest lifted, evolution has produced the largest land mammal that ever lived. She is an Indricothere and is about to give birth. After carrying her young inside her womb for two years, the moment has come to bring her calf into the world.

Ethiopia is a staggering landscape with huge plateaus shaped by tumbling waterfalls and rivers. It is a world of grassy savannahs and broken forests. Ancylotherium are a common sight amongst zebra, wildebeest and gazelles, as are the Deinotherium - a giant type of elephant with inward facing tusks. Among the trees lives the most remarkable species of all. A species of ape has evolved that spends more time on the ground and also shows signs of early humankind. This ape can walk on two legs.

For years, South America was separate from the rest of the world. The animals that evolved were unlike those found elsewhere on Earth. South America was characterized by giant "terror birds" like Phorusrhacos, Macrauchenia - a camel-like animal - and herbivores such as the Doedicurus. But 2.5 million years ago, a land bridge connected North and South America and allowed North American predators to invade. Among them was Smilodon, the largest saber-tooth cats ever, and the new top predator.

Northern Europe is a scene of grassy plenty, where many animals spend the brief Ice Age summer gorging on vegetation. Among them are the mammoths. This program follows one particular herd. Like all mammoth herds, this one is populated mostly by females - males leave the herd in adolescence. There is a 12 year-old adolescent and a 6 month old calf. The eldest member of the herd is the matriarch. It is she who makes sure they get through the necessary migration safely.