Imagine you could travel back in time
to a time long before man.
Back across 65 million years.
As you travel, you would see huge changes
in the vegetation and the climate.
Even the surface of the earth itself,
would move as mountain ranges
are pushed up by colliding continents.
Now you've reached a remarkable period in earth's history
known as the Cretaceous.
It is a very different world.
The Himalayas do not yet exist
and the Atlantic is only half as wide.
There is no grass.
Only conifer forests and fern prairies.
This is a world ruled by dinosaurs.
Giant reptiles like Tyrannosaurus,
a five-ton predator, stalked the landscape.
In Walking With Dinosaurs,
we will show you how these magnificent creatures live.
How they eat, fight, and reproduce.
And you will witness how the forces of nature
conspire to drive these animals to extinction.
But this series will also take you back much further.
Back to the Jurassic period.
A time when life on earth was at its most spectacular.
The creatures here bathe in a warm, tropical climate.
There are no ice caps at the poles.
Flowers and broad-leaved trees are yet to evolve.
In the air and on the land,
the world is dominated by reptiles
and by far the most common are the dinosaurs.
But they are not the only giants.
Huge Pterosaurs ruled the skies and below them,
massive marine reptiles harvest the rich oceans.
However, first this series will go back even further
to discover where dinosaurs came from.
This is our own earth during the Triassic period.
Here, there are no separate continents.
Just one giant land mass called Pangaea.
It is a harsh place, dominated by deserts.
The Triassic has already seen many different varieties
of ancient reptiles come and go.
But now, out of this dry wilderness
has appeared something revolutionary.
A family of reptiles destined to shape
the course of life on earth
for the next 160 million years,
these are the first dinosaurs
and this is where our story begins.
First light across the western hills
of earth's only continent: Pangaea.
This world has been ruled by one group of giant reptiles
for over 50 million years.
But these ancient creatures have had their day.
All over these lush fern prairies,
a grim evolutionary battle has broken out
among the newer types of reptile
for supremacy of this strange world.
On these Triassic proving grounds,
dinosaurs are still comparatively rare,
but they are beginning to show the first signs
of their future success.
It is the end of the wet season
and the local river is full
but it will not remain this lush
and ahead lies nine months with no rain.
One type of reptile has evolved to thrive in drought.
Dinosaurs like the Coelophysis
can survive on very little water.
She is also light-boned, fast,
and she is beautifully adapted for killing.
Dinosaurs first appeared around 10 million years before
as small predators, but what makes them unique,
is special hips and ankles
that allow them to stand perfectly balanced on two legs.
With lightening fast reactions,
they are built to survive.
A growing chorus of calls
signals the arrival of a huge herd of Placerias.
They are making their way down from the fern scrubland
for their morning drink.
These impressive one-ton beasts
are not related to dinosaurs.
They are a much more ancient type of reptile.
Once, there were many different varieties
of these powerful creatures swaggering across the landscape.
But now, the Placerias are the only ones of their kind
that remain.
They are an endangered species.
Despite their fearsome appearance,
they are actually gently herbivores.
Their tusks are used for digging up roots.
But on two angry males,
these tusks can make lethal weapons.
For the swift Coelophysis, Placerias are prey.
This young female targets the old and weak
in the slow-moving herd.
One day, the descendants of dinosaurs like Coelophysis
will take over this world.
But it is their speed and agility
that gives them the edge in the mid-Triassic.
Further down river is one of the Triassic's
most bizarre animals.
The Cyndont is the missing link
between reptiles and mammals.
As he runs, his backbone moves from side to side
like a reptile's,
but he has hair and lives down a burrow like a mammal.
Deep inside, his mate sleeps on a bed of lichen.
The bond between Cynodonts is extraordinarily strong.
They pair for life.
Like all land reptiles, they lay eggs.
But after hatching,
the young are utterly dependent on their parents
and spend their first three months
feeding from special milk glands on the mother's stomach.
This form of reproduction has evolved to protect their young
from the daylight predators outside.
By day, even the father sticks close
to the safety of the burrow
and carried out domestic chores.
He only hunts at night.
In the not-too-distant future,
small, furry mammals will evolve from reptiles like these.
In the heat of the dry season,
the Placerias herd spreads out over the scrubland to feed.
Suddenly, the warm breeze changes
and there is the scent of fear in the air.
Postosuchus, a merciless ambush predator.
The largest carnivore on earth.
The terrified Placerias flee,
but they are desperately slow
and one of them now carries a mortal wound.
Their tormentor is a distant cousin of the dinosaurs,
evolved from the same reptilian ancestors.
But unlike them, she is too front-heavy
to run on two legs.
Yet the Postosuchus is easily fast enough
to keep pace with the herd.
Eventually, a combination of shock and blood loss
defeats the wounded Placerias.
The carnivore's bite has done its job.
The Placerias is now too weak to fight
and the Postosuchus has an easy meal.
As the weeks of the dry season pass,
only the vegetation around the river remains lush
and this attract exotic hunters from far and wide
like this Peteinosaurus.
She is flying reptile
who has evolved extra-long fingers
to support her delicate wing membranes.
The river's resident flying predators are dragonflies.
Insects like these evolved long before the first reptiles
and over 100 million years ago,
some took to the air and became aerial killers.
But in the Triassic era,
these hunters have become the hunted.
A jaw full of needle-sharp teeth
make short work of the insect.
Peteinosaurus have evolved strong,
light-weight bones for flight,
and like the dinosaurs, they are fast and deadly.
Reptiles are becoming the new masters of the air.
In temperatures of over 40 degrees Centigrade,
the Placerias need lots of water
and these Ancient reptiles
have to spend more time at the river,
but the herd is nervous.
They know this is a good place for an ambush.
The Postosuchus is not hunting.
She has recently eaten her fill
and also needs to come down to the river to drink.
Six meters long,
heavily built with an armored back,
she needs a huge amount of food,
and therefore has to defend a very large territory.
The only creature on the planet she fears
is another Postosuchus.
It is now the middle of the dry season
and months since any rain.
Across the scrubland, smaller rivers are drying out.
In one, a Peteinosaurus risks a cooling bath.
He constantly checks for danger.
The Cynodonts lie secure and cool
through the hottest part of the day,
but no animal here is truly safe.
The female Coelophysis
has picked up the scent of their bedding.
Soon, she is exploring the entrance
and she is not alone.
Clearly, these dinosaurs have not met Cynodonts before.
Nearby, the Placerias search for moist roots
beneath the drying ferns.
The Postosuchus once again needs food.
But her last attack left her with a tusk wound on her thigh.
A severe handicap for such a heavily built creature.
The Placerias herd spots her
before she can set an ambush,
and they mount an aggressive defense.
She will get no food here,
and in such a competitive world,
her wound may yet prove fatal.
Evening, and in the burrow,
the Cynadonts prepare for a night of hunting.
The young are more developed now
and starting to move about the nest,
but they are still vulnerable
and it will be another two months
before they can do without their parents' protection.
The adult male checks the coast is clear.
An inquisitive youngster
follows him to the end of the burrow.
Too late the male responds to his squealing pup.
Once again, he drives the dinosaurs away
but this time, they don't go far.
Nearby, a thirsty male Postosuchus
has invaded the wounded female's territory.
But this withered Triassic landscape
cannot support two giant predators
in one dry valley.
The female is too weak to fight.
After dominating her territory for a decade,
she is driven from her home.
The male uses precious water
to mark his new territory.
Meanwhile, the Coelophysis
are starting to dig the Cynodonts out.
Their situation is becoming desperate
as the dinosaurs will soon expose the nest.
As the sun sets, the pair have only one choice.
It means shattering their unique parental bond.
They eat their own young.
This denies the dinosaurs their food
and gives the Cynodonts the chance of escape.
Under the moonlight,
they seize the moment and abandon the hole.
In the morning, the Coelophysis are back.
They can still smell the Cynodonts
and it will take them some time
to realize that their work is in vain.
The dry season continues.
After her wasted effort at the Cynodont hole,
the female Coelophysis has found something
in the parched riverbed.
It is a lungfish
and the dinosaurs unique, serrated teeth
with make short work of its protective cocoon.
But she is not left alone to eat it for long.
Coelophysis numbers are on the increase
and this leads to confrontations.
The pressure of numbers
also brings other changes in behavior.
Under the merciless sun,
a flock of Coelophysis has united for a kill.
The wounded female Postosuchus
has lost the use of her back legs.
However, her might jaws could still tear a dinosaur apart.
The great carnivore's strength fails.
All the Postosuchus' heavy armor and muscle
are no more than food for the agile little dinosaurs.
Their long snouts and nibbling front teeth
can reach under her thick scale.
They eat her from the inside out.
The rains are late
and now the real test for survival begins.
As vast areas turn into red desert,
the Placerias are driven to migrate
in search of water.
But in this extreme drought,
dinosaurs have a crucial advantage over other reptiles.
When they excrete, they waste very little water.
Nowhere is this advantage more obvious
than down by the shrunken river.
Coelophysis are gathering in huge numbers
and in years of hardship like this,
it is the dinosaurs that win through.
There is little room for any other reptiles here
and without sufficient prey,
the dinosaurs swiftly turn on each other.
Cannibalism is common.
The Triassic is pushing life to its limits.
Night reveals dinosaurs are not the only animals
that have managed to cling on.
The Cynodonts have survived their brush with death
and dug another burrow hidden in some dried ferns.
Once again, the male is hunting in the darkness.
He has caught the only common prey,
a baby Coelophysis.
After nine months of drought,
at last, the rains have arrived.
Soon, the thirsty scrublands are soaking.
Inside her burrow, the female Cynodont
has laid a fresh clutch of eggs.
One day in the distant future,
this strategy of investing in their young
will pay off for their mammalian descendants.
But as mammals evolve over the next 160 million years,
they will only survive as a few small species,
clinging on at the edge of a world
dominated by dinosaurs.
Outside, that future is already arriving.
The female Coelophysis has survived the drought,
along with many of her kind.
But they have also been joined
by another type of dinosaur.
A huge herd of Plateosaurus has been drawn
to the swollen river.
It is hard to believe that these four-legged beasts
are related to Coelophysis,
but these are plant-eating dinosaurs.
Their size is the key to their success
and at four tons, they are simply too big to be threatened.
This is the shape of things to come.
The age of the dinosaurs has dawned.
20 million years later,
a massive extinction wiped out thousands of species
of reptile,
but the dinosaurs went from strength to strength.
Carnivores grew to enormous sizes,
but their prey got even bigger.
In the next program,
we meed the giants of the Jurassic.