01x04 - Ice Worlds

[bunniefuu]

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.

Warm, shallow pools are an excellent
breeding ground

for mosquitoes.

Every year, this paradise
turns into a living hell.

Hadrosaurs have surprisingly thin skin,

and so, have little defense
against bloodsucking insects.

Constant irritation makes it hard to feed,

and they become dangerously weakened.

And babies can lose blood
in life-threatening quantities.

Eventually, the herd is forced to move on
to escape the plague.

If the young can't keep up,
their mothers abandon them.

As they go higher,
stronger winds bring some relief.

But only for those able to walk that far.

Of the hundreds of hadrosaur babies born,
only one in ten survives their first year.

But those that do have a good chance
of reaching adulthood.

By nesting in this volcanic valley,

the parents give their young
the best possible start in life.

Although the short and warm polar summer
is a time of great plenty,

it can also bring perils.

Warm air rises
and becomes charged electrically.

And that creates frequent
and violent lightning storms.

In the north of America,

the lush growth
fueled by constant sunlight

has now been baked tinder-dry.

Most animals flee from the flames.

But for some,
the disaster creates opportunities.

This six-foot-long dinosaur, a troodontid,

is one of the smaller members
of the theropod group.

Its huge eyes give it acute sight,
even in this smoky gloom.

And for its size, its brain is one
of the largest on the planet.

It's the most intelligent, adaptable,
and successful hunter in the Arctic.

At the fire's edge,

troodontids gather to prey on animals
that are trying to escape the flames.

Anything that spreads the fire
creates more opportunities

for the most ingenious arctic hunter
of its time.

Success.

With the short summer over,

the forests that survived the summer fires
start to change color.

It is autumn's final flourish
before the months of darkness begin.

In the Antarctic,
ice clings to the highest mountains

even in the summer months.

But now, with temperatures falling
and the day's shortening,

the polar winter is spreading once more
across the land.

Animals must now prepare for its return.

The southern hemisphere
has its own species of dinosaurs.

These three are young Antarctopelta,
small plant-eating dinosaurs.

They're also one of this world's
most heavily armored animals.

Even so, youngsters are safer together.

This far south,

the plants on which they depend
stop growing for months on end.

As winter approaches,
these juveniles spend more time resting.

Sheltering together conserves heat
and, therefore, energy.

With powerful front limbs,
they can enlarge this winter den.

But each time they return,
they've grown a little bigger.

Their den seems a little smaller,

and the brotherly bond…

…starts to wear a little thin.

For every growing animal,
this is a vulnerable time.

A time when they need to separate

and each take its first tentative steps
to find a territory of its own.

Herds of hadrosaurs
are once again on the move.

With little to eat,
these huge herbivores return

to look for food in warmer lands…

leaving others to endure
the freezing polar winter.

Finding a suitable territory

can take animals far from
the place where their lives began.

It's a search that many will not survive.

A good territory must have a place
in which to shelter.

A cave, perhaps.

Even in the coldest months,

the temperature in most caves
hardly varies.

But he is not the first
to be attracted by this one.

This cave glows.

These are the tiny lures
of fungus gnat larvae

that produce light
to attract their insect prey.

This is the perfect place

for an Antarctopelta to escape
the worst winter weather.

He will be safe
beneath these strange living stars…

while outside, snow begins to fall.

In the coldest months,
the far north of the Arctic can freeze

into a spectacular winter wonderland.

Not all dinosaurs choose to leave
or to seek shelter.

The largest have the strength
to tough it out.

Pachyrhinosaurs.

Two-ton herbivores
with extravagantly armored heads.

They seek refuge in the forest,

stripping the last leaves
from dormant trees

and rooting through ferns
for fallen fruit.

The autumn rut is over,

but less dominant males still try
to push their way up the social hierarchy.

But they've forgotten who's in charge.

This old bull is still a formidable force

and one that few dare to challenge.

Battling males barely have time
to eat or rest.

With food now scarce,
it's hard to rebuild strength,

and injuries take longer to heal.

To make matters worse…

…the Arctic's most powerful predator
is always on the prowl.

Nanuqsaurus.

A smaller relative of T. rex,

it's still just big enough
to tackle a pachyrhinosaur.

For these ancient adversaries,
in these conditions,

the battle will be resolved
not by surprise, but by strategy.

Amongst the trees,
it's hard for the herd to stand as one.

Individuals could be quickly isolated.

The nervous herd makes a tactical retreat
to open ground.

The nanuqsaurs follow.

Out here,
the herd will be able to close ranks

and form an impenetrable wall
of armored heads and muscle.

The blizzard worsens.

It's an uneasy standoff.

These confrontations can last for days.

The herd should be safe
as long as they stick together.

But the nanuqsaurs bide their time…

and occasionally test for weakness.

The blizzard now brings a temporary truce.

But as soon as it's over, battle resumes.

In this test of nerve,

all it takes is for one animal
to break ranks…

and panic quickly spreads.

With the herd on the run,
the predators have a chance.

As the chase goes on,

one tiring bull fails
to keep up with the rest.

Until all he can do is turn
and face his attackers.

One pachyrhinosaur has lost the battle.

But the w*r will go on all winter.

The animals here
now face months of total darkness

before the sun returns and brings relief
to the extraordinary creatures

in the world of ice.

Next on Prehistoric Planet,

a flying giant the size of a giraffe
hunts its prey

amongst the tangled trees
of a prehistoric forest.

And under the canopy on this green planet,

dinosaurs ambush, display,
and even journey underground.

To discover the science
behind the stories,

go now
to the Prehistoric Planet show page.