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.

Life is at its harshest

in the far north and south of planet Earth.

Dinosaurs, however, have managed to colonize these polar regions.

In the far north of America, this tiny hunter, a dromaeosaur,

has managed to survive three months of near-total darkness.

And now, at last, spring has come.

She has a coat of feathers,

for she's able to generate heat in her body

and needs to retain all she can.

A challenge for all dinosaurs in these cold latitudes.

As she moves quickly over the surface of the snow,

she checks on the places where she has found food in the past.

In this icy world, no opportunity is too small to be ignored.

And to succeed, as usual,

you need good… timing.

Although at this time in Earth's history,

the polar regions are relatively warm,

these lands are, nonetheless, ruled by extreme seasonal change.

When the sun rises for the first time in almost three months,

every animal must be ready to make the most of the daylight

and the warmer days that are to come.

The little dromaeosaurs must work together,

if they are to take on big prey.

And here comes their first chance of the season.

A herd of hadrosaurs.

These duck-billed dinosaurs pass through here every year.

Nomads in search of the fresh vegetation brought by the spring.

They're huge.

The only chance the dromaeosaurs will have is to work as a team.

There's a river ahead, which the herd will have to cross.

And the dromaeosaurs know that some never make it.

As winter slackens its grip, meltwater begins to flow with great power.

The herd must wade through this deep, fast-flowing water.

The leaders try to select the safest crossing.

The herd follow cautiously.

Young keep close to their parents.

Putting a foot wrong here could cost them their life.

The adults, awaiting their turn, grow nervous.

And this bottleneck gives the dromaeosaurs a chance.

Their target will be the young.

Panic begins to spread through the herd.

What should have been an orderly crossing turns to chaos.

Parents and young are separated.

A lucky escape.

The column re-forms and continues its journey.

The dromaeosaurs seem to have missed their chance…

but the river has done their work for them.

There are always casualties.

It's a feast. And more food than these hunters have had all winter.

In the ice world, seasonal opportunity is brief.

Spring is short, and summer will soon be over.

There's a lot to be done before the challenges of winter return.

Downstream, as the rivers broaden and begin to slow,

they start to drop their loads of silt,

and a network of islands appears.

Some animals have already seized the moment

to assemble for the spring rituals.

Spring, at last, has truly arrived.

Dozens of male Ornithomimus are preparing

for the most important moment of their year.

These strange ostrich-like dinosaurs choose the safety of these islands

to scrape out shallow craters, the first stage in making a nest.

When the females arrive,

they will choose to mate with the males who've made the best one.

Late arrivals find that space is already in short supply.

The only space left is on the island's margin.

And finding a place to nest is only just the start.

When eggs are eventually laid,

they will need to be kept warm in a bed of vegetation.

Finding enough nesting material is not easy…

which is why some Ornithomimus resort to thievery.

One advantage of arriving late

is that your neighbors have already done the hard work.

An unguarded nest is too much of a temptation.

In colonies like this, thievery can be so common

that some nesting material, at one time or another,

will have been part of almost every nest on the island.

But robbery is risky.

Caught in the act.

A couple of hadrosaurs wander by.

They will eat leafy branches.

So, you have to be able to defend your property.

It can take several years to perfect nest-building skills.

But success doesn't only rely on experience.

In a crowded colony, there's always another potential victim.

For Ornithomimus, these river islands will provide sanctuary

for both the eggs and the young when they hatch.

Further north, temperatures are lower and conditions are tougher.

Yet that's where these enormous crested hadrosaurs are heading

to take advantage of one site in particular.

One that has something special to offer.

The long necks of these dinosaurs are particularly elegant

and give them their name.

Olorotitan, "Giant Swan."

Their calls are amplified by their head crests, which are hollow.

They're heading for one of the world's largest volcanic regions.

It's a dangerous and hostile place.

But the Olorotitans return to it, year after year…

because the volcanoes keep the ground particularly well-heated.

So, this is where they nest.

The warm volcanic sand serves as an incubator for their eggs.

And a few weeks after the arrival of the herd, the eggs hatch.

Hadrosaurs look after their young with care.

They bring mouthfuls of plants for them to eat.

Each nest may contain over 20 youngsters.

The babies have arrived at a time of brief but rich summer plenty.

Fueled by a sun that for weeks never sets,

horsetails here grow fast

and in sufficient numbers to feed the whole herd.

These plants contain more nutrients than the lushest grass.

And in the long summer days, the hadrosaur babies grow quickly.

They can reach half their adult size in their first year.

Right now, these volcanic wetlands

are the most productive places on the planet.

Both above…

and below the surface of the water.

But that very productivity brings problems for the hadrosaurs.