Walking with Beasts

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The last dinosaurs were already living on a sick planet, when their nemesis arrived - from space. A meteor ten kilometres wide slammed into Earth to mark the end of the reign of dinosaurs.

[The footage of storms, then a clear dark sky view]

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This series is about what happened next.

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The dinosaurs might be long gone, but the left the world a vicious legacy. Their direct descendants are the birds.

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At this time in Europe's history, Germany is at the center of much volcanic activity, and this whole forest is riddled with geothermal springs.

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[about the Ambulocetus] Although his ancestors hunted on land, Ambulocetus has evolved to be far more at home in the water. In fact, his descendants will take this to a greater extreme: you are looking at the very earliest form of whale. Ambulocetus in fact means "walking whale".

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[as Gastornis tears of a Propalaeotherium's corpse] This is a world where birds eat horses!

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Today the Leptictidium is the survivor, but ironically the future holds a different outcome for these mammals. The Leptictidium and her kind are destined to become extinct when this hot wet world gets cooler and drier, and the world's forests start to disappear. Ambulocetus is the one with the big future: he is the ancestor of the whales, the most magnificent dynasty of mammals, and mammals are about to take over the world!

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When the dinosaurs disappeared, so too did the gigantic marine reptiles which once terrorized the oceans. For almost twenty-five million years, there was nothing around to eat the sharks. But there are now awesome new monsters of the deep.

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It is the late Eocene, and the world is still a hot one. However it is drier than before, and so where once the land was completely covered in lush rain forest, there are now more open spaces. Freed from the constraints of living in dense forests, some mammals have started to get larger. Here on the scrub plains, big is beautiful.

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Like dinosaurs before them, mammals dominate the planet. But they are about to undergo their severest challenge. The climate change the world has seen so far is mild compared to what is coming.

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[about Basilosaurus] Four times the length of a great white shark, this female weighs sixty tons. Incredible to think then, that their ancestors were tiny, furry, shrew-like animals that lived in trees!

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For the first time in hundreds of millions of years, the sea is freezing at the Poles, throwing ocean currents into turmoil. For a whale that needs on average eighty kilograms of food a day, the slightest change in fish stocks is bad news. She is at the top of a food chain that is about to collapse, and she has just become pregnant.

Narrator:
Against the odds, she and her calf have survived. Sadly, what the have been through is merely the start of the climate chaos to follow. Which will end the Eocene period and cause the largest extinction, since the death of the dinosaurs. As devastating as any meteor, will be the catastrophic disruption of the oceans currents caused by the gradual freezing of Antarctica. Like a giant El Nino, only much, much worse. 20% of living things on earth will die out. Whales as a group will survive, but basilosaurus and her kind will not be among them.

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Out of the darkness emerges a twelve ton giant. She is an Indricothere, and she is about to give birth.

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It is a time called the Oligocene. The world has just been through years of catastrophic climate change, that led to the extinction of one species in five.

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[about the Enteldont] The bully of the plains. These are distant relatives of the pig. Two metres tall, aggressive, built like tanks, but with a brain no bigger than an orange.

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[about the Indricotheres] Not since the dinosaurs has nature got this big!

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Indricotheres are related to rhinos, but their size is in a different league. A fully grown male stands over 7 meters tall, and weighs in at 50 tons, that's equivalent to eight modern rhinos. No other land animal even comes close.

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[about Hyaenodon] Hyaenodon's jaws have a bone-shattering force of over one thousand pounds per square inch. One bite breaks the Chalicothere's neck.

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The dry season is transformed the landscape. It's as if the whole life-blood has drained out of the plains. This is what it means to be a seasonal world - it hasn’t rained for months, there is no greenery left to eat, and there is precious little to drink. Here in Mongolia, mammals have evolved to cope with even these kinds of conditions, but at this time of year they are put under the greatest stress.

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[about the Indricothere calf] He is never again going to have the protection of his mother. The rest of his life, he will spend alone.

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Some animals can show emotion. These unique creatures are reacting to the death of one of their group with what can only be described as grief.

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One reason that our origins begin here in Africa is that it's an ideal habitat for an upright ape. A patchwork of forest and savannah.

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This is the northern end of the Great African Rift Valley: a staggering landscape, created by fractures in the continent. This is the cradle of evolution for mankind!

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[about Australopithecus] A type of ape has evolved that clearly shows the first signs of becoming more human. What makes them closer to us than other apes is not their brains, which are only one third of the size. It's not their skin, which is hairy. It's something they do that other apes just don't: something that will one day lead them to be described as a missing link. These apes walk upright!

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[about Deinotherium] They are as tall as giraffes, but weigh fourteen times as much.

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Apes have a long road to travel yet. Outwardly they are almost human, but their brains are no bigger than a chimpanzee's. It will be at least another two million years, before any ape has a decent conversation.

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Meat is only a small part of the Australopithecus diet, but it will become more important in the future, for more human-like apes. An increase in meat eating will go hand in hand with an increase in brain size. Meat contains nutrients vital for big brains. Intelligent apes will develop special tools to get meat, until eventually they'll make weapons, and won't be scavengers, but predators.

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For forty million years, the plains of South America have been ruled by an awesome group of predators. The aptly named 'Terror Birds'. [after a long pause] But recently all this has changed. A new breed of killer has arrived, one fierce enough to terrorize the Terror Birds. Smilodon, the fabled sabre tooth. The most powerful big cat of all time!

Narrator:
[about Smilodon] There is no such thing as a sabre tooth tiger. The correct name for these beasts is sabre tooth cats, and there have been many different species. The largest, at over 300 kilograms, is this one - Smilodon, which means knife tooth. Originally from North America, they came to South America two million years ago. The balance of life here changed as they took over the role of top predators.

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The short, violent reign of the brothers is over.

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[as the cats creep up on their prey] One false move, and they will have to start all over again.

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[about the Terror Birds] South America is not the only place Terror Birds are doing well. Once the land bridge opened up to North America, they were one of the few creatures to spread north successfully. While these Terror Birds pick over Smilodon's leftovers, their cousins are running riot in Texas and Florida. They only died out just before modern humans appeared.

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[about the Giant Ground Sloth] They might be herbivores, but they will eventually go for carrion to supplement their diet, and when they do, nothing gets in their way.

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Smilodon were very successful predators, and survived up until as recently as ten thousand years ago, but eventually the world around them changed too much. The climate became cooler and drier. The larger prey they specialized in killing disappeared. The sabre tooth world came to an end.

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[about Neanderthal] The Neanderthals are supreme hunters, which is why they have lasted over two hundred and sixty thousand years. But they have a weakness; they do not adapt well to change. As a result of the harsher climate, the arrival of other humans, Neanderthals are fast disappearing. In another two thousand years, they'll be gone altogether.

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This ice age is in fact only one of many. Two and a half million years ago the earth's climate started on a roller coaster of warmer and colder periods. There have been almost 50 ice ages so far, but this is the coldest yet.

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Mammoths will last another twenty-four thousand years. They are superbly adapted for this cold world. But when it gets warm again, the grassy plains they depend on will disappear.

[last line of the series]

Narrator:
We have since built museums to celebrate the past, and spent decades studying prehistoric lives. And if all this has taught us anything, it is this: no species lasts forever.