Prehistoric Planet

Surely one of the most remarkable animals that had 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 southern shores of the great inland sea

that splits North America.

And the tracks of the land's top predator.

A Tyrannosaurus rex taking a swim.

Hollow, air-filled bones and powerful hind limbs

make T. rex very effective swimmers.

This is an adult male with his young family.

His offspring are now just old enough to follow him on a journey

to one of the many offshore islands that fringe this coast.

It's a short enough crossing, but it can still be a dangerous one.

A mosasaur.

A giant marine lizard over twice the size of a tyrannosaur

and weighing over 15 tons.

It's the largest predator on the planet.

Turtles are normally on a mosasaur's menu.

But this brood would make a welcome snack.

An adult T. rex, even in water,

could still defend itself very effectively.

But the young must stay close.

Tyrannosaurus rex often lose at least two-thirds

of their original brood of 15 or so in the first year.

Now there are only four.

The island offers safety and the promise of food.

Giant two-ton turtles are here to nest.

But this is the one that has drawn him here.

It's dead, and the tyrannosaur has smelled its rotting body.

If he can just get to the underbelly,

he will have over 2,000 pounds of easy meat.

T. rex has the most powerful jaws in nature.

And can bite with the force of over five tons.

The young are keen for a taste, but he's not sharing it.

It's time for them to learn to hunt for themselves.

The beach, however, doesn't look very promising.

But as the evening approaches, things start to change.

Baby turtles are beginning to hatch from the sand and rush down to the sea.

The young T. rex have been brought to an ideal training ground.

Hatchling turtles are the perfect size for a novice to tackle.

It pays for any hunter to be inquisitive.

There's a lot to learn.

And there's enough food here to satisfy both parent and young.

And if all else fails,

you can always steal supper from someone else.

Across the globe,

these shallow coastal seas cover an area of 25 million square miles.

Far more than even the largest continent.

That, combined with the richness of the waters,

makes them very important habitat.

Wherever land meets sea,

nutrients rise from the deep, fueling an abundance of life.

It's especially rich here in the North Atlantic,

where huge shoals of fish come close to the shore.

One kind of animal thrives in such places and forms immense colonies.

Flying reptiles. Pterosaurs.

Here, on the beaches of North Africa, there are seven different species of them.

They come here to feed, to rest, and to raise their young.

Tethydraco are well-adapted to spend time on the ground

and not only make their nests here but stay to protect their brood.

And their young certainly need protection.

The dagger beak of Phosphatodraco.

A nine-foot-tall predator that stalks through these colonies,

looking for a chance to snatch an unguarded hatchling.

But some types of pterosaurs are less well-adapted to life on land.

They have a slightly different nesting strategy.

They make their nests where they will attract less attention from predators.

Isolated cliffs like this are ideal.

Pterosaur eggs are leathery and can easily dry out,

so they need to be covered.

Beneath this pile of seaweed, something is stirring.

A tiny Alcione hatchling, just a few inches high

and weighing less than two ounces.

Their mothers left the eggs here about two months ago.

Calling to each other synchronizes hatching.

There is safety in numbers.

Their first instinct is to climb.

Hatchlings from hundreds of nests gather on the cliff-top

to prepare for their first flight.

But their wings are still unformed.

The bones of the long finger that supports their wing membrane

must first straighten and lock together, and that will take some hours.

But they can't stay here for long.

Their bones are extremely light, up to 90% air,

and that makes the effort needed to take off much easier.

Even so, test flights are essential.

There will only be one chance to get it right

when the time comes to launch.

The cliff edge creates updrafts, and they can help.

So, it pays to gather there facing into the prevailing winds

and towards the mainland.

But no one seems quite ready to take the plunge.

Until, at last, one youngster sets them all on their way.

They're not heading for the beach and its colony.

They need to get to the mist forest that lies beyond.

Barbaridactylus.

Powerful, predatory pterosaurs that normally catch fish.

But the hatchlings are too good to miss.

One way to take evasive action is to simply fold their wings and drop.

But losing height will make it harder for them to reach the forests.

A crash landing in the colony.

It's no place for a hatchling on its own.

A lucky survivor from the first wave of hatchlings…

still heading in the right direction.

Sanctuary.

Of the hatchlings that left the stack, few get as far as this.

But for them,

this forest offers all the shelter and food that a young pterosaur needs.

For the next five years, this will be their home.

Then, they will be large enough to join the adults,

catching fish out on the open ocean.

Some marine animals that spend all their lives fishing out at sea

must occasionally visit the coast for a very particular purpose.

In the waters off the drowned continent of Zealandia,

a long journey is coming to an end.

These are tuarangisaurs,

a type of huge marine reptile nearly 30 feet long.

This female is accompanied by her calf, about six months old.