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Imagine you could travel back
in time - to a time long before man

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Back across 65 million years

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You would see huge changes
in the vegetation and the climate

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Even the surface of the Earth itself
would move

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as mountain ranges are pushed up
by colliding continents

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You've reached a period in Earth's
history known as the Cretaceous

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It is a very different world

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The Himalayas do not yet exist and
the Atlantic is only half as wide

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There is no grass, only
conifer forests and fern prairies

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This is a world ruled by dinosaurs

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(Fierce roar)

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Giant reptiles like Tyrannosaurus,
a five-tonne predator,

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stalk the land

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In Walking With Dinosaurs,

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we will show you how
these magnificent creatures live -

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how they eat, fight and reproduce

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You will witness
how the forces of nature

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conspire to drive these animals
to extinction

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But this series will also
take you back much further

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To the Jurassic period -
when life on Earth

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was at its most spectacular

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(Low grumbling roar)

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The creatures here
bathe in a warm tropical climate -

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there are no icecaps at the poles

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Flowers and broad-leaved trees
are yet to evolve

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In the air and on the land,
the world is dominated by reptiles,

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and by far the most common
are the dinosaurs

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But they are not the only giants

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Huge pterosaurs rule the skies
and, below them,

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massive marine reptiles
harvest the rich oceans

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However, first, this series
will go back even further,

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to discover where
dinosaurs came from

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This is our own Earth
during the Triassic period

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There are no separate continents,

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just one landmass called Pangaea

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It is a harsh place
dominated by deserts

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The Triassic has already seen

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many different varieties
of ancient reptiles come and go

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But now, out of this dry wilderness,

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has appeared something
revolutionary

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A family of reptiles destined
to shape the course of life on Earth

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for the next 160 million years

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These are the first dinosaurs

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and this is where our story begins

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First light across the western hills

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of Earth's only continent, Pangaea

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This world has been ruled

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by one group of giant reptiles
for over 50 million years

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But these ancient creatures
have had their day

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All over these lush fern prairies,

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an evolutionary battle has broken
out among the newer types of reptile

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for supremacy of this strange world

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On these Triassic proving grounds,
dinosaurs are still rare,

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but they are beginning to show signs
of their future success

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(Small growl)

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It is the end of the wet season
and the local river is full

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But it will not remain this lush,

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and ahead lies nine months
with no rain

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One type of reptile
has evolved to thrive in drought

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Dinosaurs like this Coelophysis
can survive on very little water

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She is also light-boned, fast,
and she is beautifully adapted

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for killing

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Dinosaurs appeared
around 10 million years before,

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as small predators

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What makes them unique
is special hips and ankles

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that allow them to stand
perfectly balanced on two legs

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With lightning-fast reactions,
they are built to survive

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(Loud roar)

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(Trumpeting calls)

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A chorus of calls signals the
arrival of a huge herd of Placerias

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They are making their way down from
the ferns for their morning drink

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These impressive one-tonne beasts
are not related to dinosaurs

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They are a much more ancient
type of reptile

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Once there were many different kinds
of these powerful creatures,

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but now the Placerias are the only
ones of their kind that remain

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They are an endangered species

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Despite their fearsome appearance,
they are actually gentle herbivores

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Their tusks are used
for digging up roots

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(Angry growling)

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But on two angry males,
these tusks can make lethal weapons

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For the swift Coelophysis,
Placerias are prey

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This young female
targets the old and weak

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in the slow-moving herd

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(Growling and trumpeting)

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One day, the descendants
of dinosaurs like Coelophysis

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will take over this world,

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but it is their speed and agility

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that gives them the edge
in the mid-Triassic

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Further downriver is one of
the Triassic's most bizarre animals

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The cynodont is a missing link
between reptiles and mammals

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As he runs, his backbone moves

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from side to side like a reptile's,

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but he has hair and lives
down a burrow, like a mammal

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Deep inside,
his mate sleeps on a bed of lichen

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The bond between cynodonts
is very strong -

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they pair for life

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Like all land reptiles,
they lay eggs,

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but after hatching, the young are
utterly dependent on their parents

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and for the first three months,

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feed from milk glands on the mother

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This form of reproduction
has evolved

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to protect their young
from the daylight predators outside

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By day, even the father sticks close
to the safety of the burrow

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and carries out domestic chores

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He only hunts at night

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In the not too distant future,

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small furry mammals will evolve
from reptiles like these

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In the heat of the dry season,

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the Placerias herd spreads out
over the scrubland to feed

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(Low growling)

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Suddenly the warm breeze changes

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and there is the scent of fear
in the air

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(Vicious growling)

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Postosuchus,
a merciless ambush predator -

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the largest carnivore on Earth

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(Roars)

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The terrified Placerias flee,
but they are desperately slow

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and one of them is mortally wounded

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Their tormentor is
a distant cousin of the dinosaurs,

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but unlike them, she is
too front-heavy to run on two legs

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Yet the Postosuchus is easily fast
enough to keep pace with the herd

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Eventually, a combination
of shock and blood loss

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defeats the wounded Placerias

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The carnivore's bite
has done its job

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The Placerias
is now too weak to fight

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and the Postosuchus
has an easy meal

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As the weeks of the dry season pass,

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only the vegetation
around the river remains lush

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and this attracts exotic hunters
like this Peteinosaurus

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She is a flying reptile
who has evolved extra-long fingers

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to support
her delicate wing membranes

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(Rattling call)

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The river's resident
flying predators are dragonflies

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Insects like these evolved
long before the first reptiles

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Over 100 million years ago,

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some took to the air
and became aerial killers

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But in the Triassic era, these
hunters have become the hunted

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A jaw full of needle-sharp teeth

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makes short work of the insect

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Peteinosaurus have evolved strong,
lightweight bones for flight,

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and like the dinosaurs,
they are fast and deadly

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Reptiles are becoming
the new masters of the air

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In temperatures
of over 40 degrees centigrade,

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the Placerias need lots of water

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and spend more time at the river

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But the herd is nervous

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They know
this is a good place for an ambush

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The Postosuchus is not hunting

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She has recently eaten her fill

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and also needs
to come down to the river to drink

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Six metres long,
heavily built with an armoured back,

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she needs a huge amount of food

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and, therefore, has to defend
a very large territory

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The only creature on the planet
she fears is another Postosuchus

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(Loud, rasping roar)

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It is the middle of the dry season,
months since any rain

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Across the scrubland,
smaller rivers are drying out

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In one, a Peteinosaurus risks
a cooling bath

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He constantly checks for danger

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The cynodonts lie secure and cool

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through the hottest part of the day

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But no animal here is truly safe

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The female Coelophysis has picked up
the scent of their bedding

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Soon she is exploring
the entrance

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and she is not alone

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(Puppy-like growling)

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Clearly these dinosaurs
have not met cynodonts before

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Nearby, the Placerias
search for moist roots

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beneath the drying ferns

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The Postosuchus
once again needs food

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But her last attack left her
with a tusk wound on her thigh -

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a severe handicap
for such a heavily-built creature

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The Placerias herd spots her
before she can set an ambush

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and they mount an aggressive
defence

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(Angry roaring)

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She will get no food here,
and in such a competitive world,

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her wound may yet prove fatal

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Evening, and in the burrow,

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the cynodonts prepare
for a night of hunting

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The young are more developed now

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and starting to move about the nest,

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but they are stillvulnerable

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It'll be two months

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before they can do without
their parents' protection

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The adult male
checks the coast is clear

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An inquisitive youngster follows
him to the end of the burrow

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(Squealing)

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(Cynodont barks)

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Too late, the male responds
to his squealing pup

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Again, he drives the dinosaurs away,

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but this time, they don't go far

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Nearby, a thirsty male Postosuchus

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has invaded
the wounded female's territory

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But this withered
Triassic landscape

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cannot support two giant predators
in one dry valley

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The female is too weak to fight

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00:19:06,497 --> 00:19:09,057
After dominating her territory
for a decade,

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she is driven from her home

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00:19:12,091 --> 00:19:16,884
The male uses precious water
to mark his new territory

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Meanwhile, the Coelophysis are
starting to dig the cynodonts out

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Their situation
is becoming desperate

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00:19:37,582 --> 00:19:41,542
as the dinosaurs
will soon expose the nest

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As the sun sets,
the pair have only one choice

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00:19:56,022 --> 00:19:59,459
It means shattering
their unique parental bond -

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they eat their own young

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00:20:02,542 --> 00:20:05,421
This denies the dinosaurs
their food

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00:20:05,502 --> 00:20:09,382
and gives the cynodonts
the chance of escape

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00:20:17,182 --> 00:20:22,211
Under the moonlight, they seize
the moment and abandon the hole

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00:20:34,982 --> 00:20:38,180
In the morning,
the Coelophysis are back

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00:20:38,262 --> 00:20:41,778
They can smell the cynodonts,
and it will take them time

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00:20:41,862 --> 00:20:44,457
to realise their work is in vain

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00:21:01,497 --> 00:21:03,454
The dry season continues

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00:21:03,537 --> 00:21:05,415
After the cynodont hole,

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00:21:05,497 --> 00:21:10,447
the female Coelophysis has found
something in the parched river bed

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00:21:10,537 --> 00:21:14,497
It is a lungfish,
and the dinosaur's serrated teeth

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will make short work
of its protective cocoon

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00:21:18,617 --> 00:21:22,054
But she is not left alone
to eat it for long

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00:21:30,577 --> 00:21:32,933
Coelophysis numbers are increasing,

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00:21:33,017 --> 00:21:36,533
and this leads to confrontations

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(Vicious squealing)

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00:21:53,977 --> 00:21:58,768
The pressure of numbers also brings
other changes in behaviour

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00:22:03,657 --> 00:22:05,455
Under the merciless sun,

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00:22:05,537 --> 00:22:09,372
a flock of Coelophysis
has united for a kill

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00:22:09,937 --> 00:22:13,931
The wounded female Postosuchus
has lost the use of her back legs

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00:22:14,017 --> 00:22:17,727
However, her mighty jaws
could still tear a dinosaur apart

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00:22:41,222 --> 00:22:43,897
The great carnivore's
strength fails

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00:22:46,222 --> 00:22:49,693
All the Postosuchus's
heavy armour and muscle

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are no more than food
for the agile little dinosaurs

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00:22:53,942 --> 00:22:56,935
Their long snouts and nibbling teeth

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can reach under her thick scales

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They eat her from the inside out

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00:23:27,262 --> 00:23:29,015
The rains are late,

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00:23:29,102 --> 00:23:32,698
and now the real test
for survival begins

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00:23:32,782 --> 00:23:35,741
As vast areas turn into red desert,

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00:23:35,822 --> 00:23:40,613
the Placerias are driven to migrate
in search of water

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00:23:51,582 --> 00:23:54,416
But in this extreme drought,

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00:23:54,502 --> 00:23:59,019
dinosaurs have a crucial advantage
over other reptiles

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00:23:59,102 --> 00:24:03,062
When they excrete,
they waste very little water

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00:24:05,502 --> 00:24:08,301
Nowhere is this advantage more
obvious than by the shrunken river

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Coelophysis are gathering
in huge numbers,

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00:24:13,127 --> 00:24:15,403
and in years of hardship like this,

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00:24:15,487 --> 00:24:18,082
it is the dinosaurs
that win through

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00:24:18,167 --> 00:24:22,446
There is little room for other
reptiles, and without prey,

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00:24:22,527 --> 00:24:25,087
the dinosaurs swiftly
turn on each other

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00:24:27,967 --> 00:24:30,402
Cannibalism is common

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00:24:33,705 --> 00:24:37,665
The Triassic is pushing life
to its limits

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00:24:47,345 --> 00:24:50,861
Night reveals dinosaurs
are not the only animals

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00:24:50,945 --> 00:24:54,063
that have managed to cling on

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00:24:54,145 --> 00:24:57,343
The cynodonts have survived
their brush with death

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00:24:57,425 --> 00:25:01,055
and dug another burrow
hidden in some dried ferns

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00:25:01,145 --> 00:25:05,583
Once again,
the male is hunting in the darkness

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00:25:06,825 --> 00:25:08,782
(Growling, animal squeals)

253
00:25:12,385 --> 00:25:14,980
He has caught
the only common prey -

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00:25:17,305 --> 00:25:19,262
a baby Coelophysis

255
00:25:26,539 --> 00:25:29,455
(Thunder rumbles)

256
00:25:37,339 --> 00:25:39,808
After nine months of drought,

257
00:25:39,899 --> 00:25:42,494
at last the rains have arrived

258
00:26:15,779 --> 00:26:19,216
Soon, the thirsty scrublands
are soaking

259
00:26:33,579 --> 00:26:39,018
In her burrow, the female cynodont
has laid a fresh clutch of eggs

260
00:26:39,099 --> 00:26:43,252
One day in the future, this strategy
of investing in their young

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00:26:43,339 --> 00:26:46,298
will pay off
for their mammalian descendants

262
00:26:46,379 --> 00:26:50,339
But as mammals evolve
over the next 160 million years,

263
00:26:50,419 --> 00:26:53,412
they'll only survive
as a few small species,

264
00:26:53,499 --> 00:26:57,698
clinging on at the edge
of a world dominated by dinosaurs

265
00:27:00,179 --> 00:27:04,173
Outside,
that future is already arriving

266
00:27:06,699 --> 00:27:11,171
The female Coelophysis
has survived the drought,

267
00:27:11,259 --> 00:27:13,694
along with many of her kind

268
00:27:16,219 --> 00:27:21,294
But they have also been joined
by another type of dinosaur

269
00:27:24,259 --> 00:27:26,899
(Low, rumbling call)

270
00:27:34,259 --> 00:27:36,091
A huge herd of Plateosaurus

271
00:27:36,179 --> 00:27:39,138
has been drawn to the swollen river

272
00:27:39,219 --> 00:27:41,176
It is hard to believe that these
beasts are related to Coelophysis,

273
00:27:41,259 --> 00:27:42,932
but these are
plant-eating dinosaurs

274
00:27:49,106 --> 00:27:52,577
Their size is the key
to their success,

275
00:27:52,666 --> 00:27:58,105
and at four tonnes, they are
simply too big to be threatened

276
00:28:01,546 --> 00:28:05,176
This is the shape of things
to come -

277
00:28:05,266 --> 00:28:07,383
the age of the dinosaurs has dawned

278
00:28:35,435 --> 00:28:37,427
20 million years later,

279
00:28:37,515 --> 00:28:40,747
extinction wiped out
thousands of species of reptile,

280
00:28:40,835 --> 00:28:44,272
but the dinosaurs
went from strength to strength

281
00:28:44,355 --> 00:28:49,430
Carnivores grew to enormous sizes,
but their prey got even bigger

282
00:28:49,515 --> 00:28:51,825
In the next programme,

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00:28:51,915 --> 00:28:54,874
we meet the giants of the Jurassic