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

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

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Tyrannosaurus rex.

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An animal to spark the imagination
for all of us.

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What kind of an animal was it?

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What did it look like? How did it live?

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Now, scientific research has answered
such questions.

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And not just about T. rex,

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but the other species
that lived alongside it.

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

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Planet Earth, 66 million years ago.

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The skies are filled with flying giants.

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In the seas,
monstrous reptiles patrol the depths.

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And on land, dinosaurs of every kind,

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all facing the struggle to survive.

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

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This is their story.

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The west of South America

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

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Few animals venture here,

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

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Dreadnoughtus.

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

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These are all males,

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

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

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Crowds of females
scrutinize the newly arriving males,

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assessing their strength and suitability.

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The titanosaurs' immense necks

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are supported by
an ultralightweight air-filled skeleton.

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Their hollow neck bones
are connected to a series of bellows

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that inflate bizarre gular air sacs.

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

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This huge bull, white with dust,

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has held the center stage for two weeks.

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He weighs nearly 50 tons.

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And his display has, so far,

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intimidated all challengers.

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But this new arrival…

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is not deterred.

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Lifting up such a huge body is exhausting.

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It's a battle of endurance.

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

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stabbing with sharp dagger-like spikes
on each thumb

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and raking the skin with their teeth.

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Until, eventually…

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the knockout blow.

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The old bull's rule is finally over.

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The young victor takes his turn
on the center stage.

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

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Even though some animals
are well adapted to desert conditions,

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their survival is often on a knife-edge.

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Especially here in Asia,

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where, in the height of summer,

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temperatures soar
above 60 degrees Celsius…

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and water evaporates in an instant.

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There are
ferocious-looking reptiles here too.

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But this little lizard
is only a few inches long.

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Here, getting a meal is never easy.

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This immense carcass could be promising.

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A dead sauropod.

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A potential feast for many.

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But, strangely, all is quiet.

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Tarbosaurus…

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the equivalent, in this desert, of T. rex.

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They keep everyone else away.

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But for the lizard,
they might bring an opportunity.

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

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

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Time to be bold.

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A Velociraptor.

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Time to be careful.

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Because Velociraptors often hunt together.

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The tarbosaurs move on.

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And now the pterosaurs can come down…

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and claim a share of the carcass.

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For the little lizard,
the opportunity has gone.

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

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and some dinosaurs manage to do so
very effectively indeed.

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Mononykus is a desert specialist.

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Like many desert animals,

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

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Bare legs help keep her body cool.

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

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and they provide her with a super sense.

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

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Such hypersensitive directional hearing

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

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

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Mononykus, single giant claw.

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

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And she has
another special piece of equipment.

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A flexible tongue
twice the length of her head.

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An excellent protein-packed meal,

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if only termites
weren't quite so irritating.

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Specialists like Mononykus can thrive
in this arid desert.

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But such conditions
don't always stay the same.

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On rare occasions,

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

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A desert storm,
bringing with it welcome rain.

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

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It transforms this landscape
in unexpected ways.

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Seeds that have been lying dormant
burst into life.

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They transform this arid landscape
in a matter of days.

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And with the vegetation comes
an abundance of food,

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if you know how to catch it.

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Enantiornithines, an ancient type of bird.

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But perhaps a little too big to tackle.

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

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Oh, dear.

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Finally, she's got something.

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But these new challenges will be brief.

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One thing is certain in the desert:

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Searing heat and scorched earth
will soon return.

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Flowers will be nothing more
than a distant memory.

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It's not just the unrelenting power
of the sun

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that makes deserts so inhospitable.

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So too do winds.

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Here in central Asia,
they rip across the landscape,

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drying out the land still further
and uprooting vegetation.

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Large dinosaurs keep on the move

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to try to cope
with these harsh conditions.

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These duck-billed dinosaurs
are Barsboldia.

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They are long-distance specialists

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

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But on rare occasions,
there is an abundance.

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When rain does fall,

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

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

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and creates an oasis.

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

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Some dwarf everyone else.

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The Mongolian titan.

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They are colossal.

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Weighing over 70 tons,

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

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

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There may be a crowd,

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

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Such a gathering attracts attention.

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A tarbosaur.

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

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With so many thirsty mouths
drinking day and night,

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the water doesn't last long.

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The animals disperse,

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and once again, the harsh,
arid conditions return.

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Over millions of years,
water has carved some deserts

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into spectacular landscapes…

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as here in North Africa.

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These canyon lands offer some
desert visitors special opportunities.

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

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can exploit the thermals
with effortless skill…

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and so cover great distances,

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despite the fact
that some have enormous head crests.

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

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in their thousands.

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

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so they're safe places on which to land.

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Large males select an area
in which to perform their displays

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whilst eager young bachelors
circle overhead.

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Territory holders warn off
any challengers.

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A message that sometimes needs
to be violently reinforced.

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

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

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They are sneaky males
that look like females

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and so, can try to remain unnoticed.

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It's a dangerous game to play…

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because the large males
are regularly on patrol.

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And they perform their displays.

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The sneak has been spotted.

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But in fact…

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he caught the eye of the large male.

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But the sneak pretends
to be a reluctant female…

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and rejects the male's advances.

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Now, back to the mission in hand…

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and time to make his move.

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Success.

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Large males might seem more attractive,

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

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by mating
with as many partners as they can…

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whether they're impressively adorned
or just sneaky.

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It's not just extraordinary,
bizarre animals

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that live in the deserts
of the prehistoric planet.

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There are strange,
otherworldly landscapes too.

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Such as here in South America.

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This may look like a dusting of snow,

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

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

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

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

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Yet some dinosaurs manage to do so.

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Secernosaurus, a type of small hadrosaur.

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Although they can survive
on a poor-quality diet,

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every decade or so
this area dries out so extremely

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that almost all the vegetation
shrivels and dies.

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

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00:33:12,326 --> 00:33:15,829
But some of the older,
more experienced individuals

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may remember other potential sources
of food and water.

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

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but to continue traveling
across its baking dunes.

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

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00:33:44,983 --> 00:33:47,110
And that makes navigation tricky.

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The herd prefers to travel at night.

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00:34:30,654 --> 00:34:32,197
It's not only cooler

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

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through the featureless
yet ever-changing desert.

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00:34:42,291 --> 00:34:45,210
A map in the sky.

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00:34:48,172 --> 00:34:50,132
Like many migrating animals,

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hadrosaurs
can recognize celestial signposts.

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00:35:00,475 --> 00:35:04,563
By day, the blistering sun
still beats down from overhead.

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

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00:35:28,003 --> 00:35:30,881
But there is something else
that may help them.

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00:35:35,928 --> 00:35:40,140
The deep, rumbling sound of waves
crashing onto the distant shoreline

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travels for miles through the dunes.

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00:35:44,978 --> 00:35:49,274
The sound is so low
that many animals cannot hear it.

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00:35:49,358 --> 00:35:54,696
But hadrosaurs can, and so are able
to find their way towards the coast.

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00:35:57,115 --> 00:36:01,787
But this desert still has one more
obstacle that must be overcome.

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00:36:03,580 --> 00:36:07,376
Giant coastal dunes block their path.

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Steep, unstable sand
saps energy with every step.

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They have made it.

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00:37:32,794 --> 00:37:38,383
And their first reward is to lick droplets
of water that condense on their skin

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from the fog that forms
where dunes and ocean meet.

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00:37:53,232 --> 00:37:57,986
And this fog also nourishes
a rich coastal paradise.

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This is enough to feed the herd for now,

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00:38:14,253 --> 00:38:18,090
but once it runs out,
they will be forced to move on…

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00:38:22,219 --> 00:38:25,222
and once more endure the trials of life

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in the deserts of the prehistoric planet.

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Next on Prehistoric Planet,

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one of the strangest dinosaurs
that has ever lived.

230
00:38:41,154 --> 00:38:46,159
A bizarre, duck-billed giant
feeds in a vast inland swamp.

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00:38:48,078 --> 00:38:50,497
And as fresh water flows
from source to sea,

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00:38:50,581 --> 00:38:53,834
it shapes the lives of all it touches.

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00:38:55,127 --> 00:38:58,213
To discover the science
behind the stories,

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00:38:58,297 --> 00:39:02,718
go now
to the Prehistoric Planet show page.