Prehistoric Planet

Surely, one of the most remarkable animals that has ever existed,

and certainly one of the most famous, is a dinosaur.

Tyrannosaurus rex.

An animal to spark the imagination for all of us.

What kind of an animal was it?

What did it look like? How did it live?

Now, scientific research has answered such questions.

And not just about T. rex,

but the other species that lived alongside it.

And the latest imaging technology enables us to bring them all to life.

Planet Earth, 66 million years ago.

The skies are filled with flying giants.

In the seas, monstrous reptiles patrol the depths.

And on land, dinosaurs of every kind,

all facing the struggle to survive.

We now know so much about a world that was ruled by the dinosaurs.

This is their story.

The forests in South America contain some of the world's tallest trees.

They can grow to a height of over 300 feet.

But there are animal giants here too.

Plant-eating dinosaurs.

These are Austroposeidon.

They're 80 feet long.

And they have colossal appetites.

Their teeth are used not to chew,

but simply to cut.

A herd like this one can consume ten tons of vegetation every day.

They prefer the tender, young leaves that grow on the tips of the branches.

But if they find trees that are even taller than they are,

they're not defeated.

They use their great weight and their 8-inch-thick breastbone

to simply push the trees over.

Success.

But life in the forest is always a battle.

Especially when new space is created.

Plants race to claim the light…

and use every kind of method to gain the upper hand.

The gap in the canopy is soon closed.

Over three-quarters of the world's land is covered by plants and trees.

This prehistoric planet is a green planet.

Many different species of dinosaur live in forests.

Triceratops, one of the biggest in North America.

They can be 26 feet long.

The huge frills on their heads are used for protection when they fight.

But plants have defenses too.

Poisonous toxins.

These are particularly dangerous for youngsters.

This calf weighs only a 50th of the weight of his mother.

And the plant's toxins could make him very sick indeed.

But Triceratops have a way of dealing with such poisons.

They use an antidote.

One source of it lies in a cave to which they pay regular visits.

This youngster, however, has never been in here before.

They have to find their way along a passage

that, over many millennia, has been eroded by an underground river.

They are now beyond the reach of light.

They can't see a thing.

The calf must stick close to his family.

But not too close.

Now, one wrong turn could be disastrous.

At last, the herd reaches the place they need to visit.

This is the antidote: a special clay.

These are known as clay licks, and they're visited time and again.

But someone is missing.

Where is her calf?

Luck was on the youngster's side.

Once he's lined his stomach with clay,

he too will be protected from the poisons in the leaves on which he feeds.

Soon they will all head back to the forest and daylight.

In fact, very little of the sun's light

reaches the floor of these dense forests.

In Patagonia,

the thick vegetation stretches unbroken for hundreds of miles.

But occasionally, there are mysterious clearings, like this one.

It's the work of a two-ton, 12-foot tall Carnotaurus. A male.

Clearing this patch has taken him a long time.

And it needs constant attention if it is to remain tidy.

It's a stage on which he can show off to females.

All is ready, and he announces the fact.

His calls are low-pitched

and travel much farther through the dense vegetation

than higher-pitched ones would do.

At last, a female arrives.

She's bigger than the male and more powerful.

Now, somehow, he must impress her.

And he may only get this one chance.

She watches him carefully.

If he is going to impress her,

he must do so in the most extraordinary way.

He doesn't have huge antlers, nor a spectacular tail.

But he does have a pair of tiny, apparently useless arms.

And each has a ball and socket joint at its base

that enables him to move them independently.

Not today.

How could he have done better? Who knows?

For now, it's back to litter picking.

This is East Asia.

In these mountain forests, autumn arrives early.

This is when many trees produce their fruit.

And amongst the most highly prized are the nuts of the Ginkgo tree.

A bonanza for dinosaurs called Corythoraptors.

Although they have feathers, they're flightless.

These have found a particularly abundant fall of fruit.

But such gatherings can attract unwelcome attention.

Qianzhousaurus, the top predator in these Asiatic forests.

This is a female, over 30 feet long.

If she is to catch a Corythoraptor, she'll have to get close.

There's not much cover here.

But her prey have still not noticed her.

She has failed.