01x02 - Deserts

[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.

The west of South America

and one of the most desolate places
on this prehistoric planet.

Few animals venture here,

yet it is the stage for one of the most
extraordinary gatherings on Earth.

Dreadnoughtus.

Titanosaurs. Eighty-five feet long
and weighing 40 tons.

These are all males,

and they're many miles
from their rich forest feeding grounds.

They come here for only one reason:
To fight for the chance to mate.

Crowds of females
scrutinize the newly arriving males,

assessing their strength and suitability.

The titanosaurs' immense necks

are supported by
an ultra lightweight air-filled skeleton.

Their hollow neck bones
are connected to a series of bellows

that inflate bizarre gular air sacs.

Those males with the most impressive
displays will attract the most females.

This huge bull, white with dust,

has held the center stage for two weeks.

He weighs nearly 50 tons.

And his display has, so far,

intimidated all challengers.

But this new arrival…

Is not deterred.

Lifting up such a huge body is exhausting.

It's a battle of endurance.

As the conflict intensifies,
each fighter tries to wound the other,

stabbing with sharp dagger-like spikes
on each thumb

and raking the skin with their teeth.

Until, eventually…

The knockout blow.

The old bull's rule is finally over.

The young victor takes his turn
on the center stage.

The price of defeat, for some,
is very high.

Even though some animals
are well adapted to desert conditions,

their survival is often on a knife-edge.

Especially here in Asia,

where, in the height of summer,

temperatures soar
above 60 degrees Celsius…

And water evaporates in an instant.

There are
ferocious-looking reptiles here too.

But this little lizard
is only a few inches long.

Here, getting a meal is never easy.

This immense carcass could be promising.

A dead sauropod.

A potential feast for many.

But, strangely, all is quiet.

Tarbosaurus…

The equivalent, in this desert, of T. Rex.

They keep everyone else away.

But for the lizard,
they might bring an opportunity.

If there is one thing
that attracts flies more than a carcass…

It's a sleeping tarbosaur
that has been feeding on that carcass.

Time to be bold.

A Velociraptor.

Time to be careful.

Because Velociraptors often hunt together.

The tarbosaurs move on.

And now the pterosaurs can come down…

And claim a share of the carcass.

For the little lizard,
the opportunity has gone.

Making the most of fleeting chances
is key to surviving in the desert,

and some dinosaurs manage to do so
very effectively indeed.

Mononykus is a desert specialist.

Like many desert animals,

she must patrol a huge area
if she is to find enough food.

Bare legs help keep her body cool.

Feathers on her body
shield her from the sun's rays,

and they provide her with a super sense.

They form facial discs that help her
detect the faintest of sounds.

Such hypersensitive directional hearing

gives her a mental map
of this hollow log and what lies within.

She now uses the weapon
that gives this hunter its name.

Mononykus, single giant claw.

Just what she needs
to open a termite's nest.

And she has
another special piece of equipment.

A flexible tongue
twice the length of her head.

An excellent protein-packed meal,

if only termites
weren't quite so irritating.

Specialists like Mononykus can thrive
in this arid desert.

But such conditions
don't always stay the same.

On rare occasions,

cooler mountain winds sweep in
and mix with the rising hot air.

A desert storm,
bringing with it welcome rain.

She may never before
have seen the land soaked like this.

It transforms this landscape
in unexpected ways.

Seeds that have been lying dormant
burst into life.

They transform this arid landscape
in a matter of days.

And with the vegetation comes
an abundance of food,

if you know how to catch it.

Enantiornithines, an ancient type of bird.

But perhaps a little too big to tackle.

It can be hard adapting
to such a different and unfamiliar world.

Oh, dear.

Finally, she's got something.

But these new challenges will be brief.

One thing is certain in the desert:

Searing heat and scorched earth
will soon return.

Flowers will be nothing more
than a distant memory.

It's not just the unrelenting power
of the sun

that makes deserts so inhospitable.

So too do winds.

Here in central Asia,
they rip across the landscape,

drying out the land still further
and uprooting vegetation.

Large dinosaurs keep on the move

to try to cope
with these harsh conditions.

These duck-billed dinosaurs
are Barsboldia.

They are long-distance specialists

and can go without water
for an astonishing length of time.

But on rare occasions,
there is an abundance.

When rain does fall,

it can seep into the land
and travel great distances underground.

Until, in some special places,
the water rises to the surface

and creates an oasis.

Open water attracts desert animals
of every kind from many miles away.

Some dwarf everyone else.

The Mongolian titan.

They are colossal.

Weighing over 70 tons,

they are among the biggest animals
to have ever walked the Earth.

A risky place for a tiny Mononykus
to come for a drink.

There may be a crowd,

but if you've got the longest neck
on Earth, you can jump the queue.

Such a gathering attracts attention.

A tarbosaur.

But like everyone else,
the hunter is here just for water.

With so many thirsty mouths
drinking day and night,

the water doesn't last long.

The animals disperse,

and once again, the harsh,
arid conditions return.

Over millions of years,
water has carved some deserts

into spectacular landscapes…

As here in North Africa.

These canyon lands offer some
desert visitors special opportunities.

With a 17-foot wingspan,
Barbaridactylus, a type of pterosaur,

can exploit the thermals
with effortless skill…

And so cover great distances,

despite the fact
that some have enormous head crests.

Every year, males and females
gather at these special places in the sky

in their thousands.

There are no ground predators
on the summits of these isolated plateaus,

so they're safe places on which to land.

Large males select an area
in which to perform their displays

whilst eager young bachelors
circle overhead.

Territory holders warn off
any challengers.

A message that sometimes needs
to be violently reinforced.

But you don't necessarily
have to be a heavyweight to succeed.

There are some males
that don't develop the huge head crest.

They are sneaky males
that look like females

and so, can try to remain unnoticed.

It's a dangerous game to play…

Because the large males
are regularly on patrol.

And they perform their displays.

The sneak has been spotted.

But in fact…

He caught the eye of the large male.

But the sneak pretends
to be a reluctant female…

And rejects the male's advances.

Now, back to the mission in hand…

And time to make his move.

Success.

Large males might seem more attractive,

but the females, it seems,
ensure producing the fittest young

by mating
with as many partners as they can…

Whether they're impressively adorned
or just sneaky.

It's not just extraordinary,
bizarre animals

that live in the deserts
of the prehistoric planet.

There are strange,
otherworldly landscapes too.

Such as here in South America.

This may look like a dusting of snow,

but these great dunes are composed
not of sand, but of gypsum.

Gypsum is a fine, white mineral
that dissolves in water so easily,

it can only exist in solid form
in the driest areas on Earth.

These dunes are so dry
that living here is almost impossible.

Yet some dinosaurs manage to do so.

Secernosaurus, a type of small hadrosaur.

Although they can survive
on a poor-quality diet,

every decade or so
this area dries out so extremely

that almost all the vegetation
shrivels and dies.

With young to care for,
this could be the end of the herd.

But some of the older,
more experienced individuals

may remember other potential sources
of food and water.

And they know that the way to survive
is not to try to leave the desert

but to continue traveling
across its baking dunes.

With high winds and shifting sands,
the desert is always on the move.

And that makes navigation tricky.

The herd prefers to travel at night.

It's not only cooler

but also reveals a map that could
enable an animal to find its way

through the featureless
yet ever-changing desert.

A map in the sky.

Like many migrating animals,

hadrosaurs
can recognize celestial signposts.

By day, the blistering sun
still beats down from overhead.

Even if they can find shade,
this for some could be journey's end.

But there is something else
that may help them.

The deep, rumbling sound of waves
crashing onto the distant shoreline

travels for miles through the dunes.

The sound is so low
that many animals cannot hear it.

But hadrosaurs can, and so are able
to find their way towards the coast.

But this desert still has one more
obstacle that must be overcome.

Giant coastal dunes block their path.

Steep, unstable sand
saps energy with every step.

They have made it.

And their first reward is to lick droplets
of water that condense on their skin

from the fog that forms
where dunes and ocean meet.

And this fog also nourishes
a rich coastal paradise.

This is enough to feed the herd for now,

but once it runs out,
they will be forced to move on…

And once more endure the trials of life

in the deserts of the prehistoric planet.

Next on Prehistoric Planet,

one of the strangest dinosaurs
that has ever lived.

A bizarre, duck-billed giant
feeds in a vast inland swamp.

And as fresh water flows
from source to sea,

it shapes the lives of all it touches.

To discover the science
behind the stories,

go now
to the Prehistoric Planet show page.