Original subtitles

Somewhere on the edge of a Jurassic forest,

a mother dinosaur is laying her eggs

(Deep grunting)

She is a 25-tonne Diplodocus

Each football-sized object

is carefully placed in a deep trench

Tenderly, she buries her clutch

and then abandons them

Out on the fern plains, the rest of her gigantic herd grazes

She is one of a family of dinosaurs called the sauropods

that dominate this period in Earth's history

They are the largest animals

that will ever walk the planet

This is the Jurassic period,

and the giant continent of Pangaea

that stretched from pole to pole is now breaking up

It is much wetter than the earlier Triassic period

and where there were once deserts,

there are now vast forests of conifer trees

It is 70 million years since dinosaurs first appeared on Earth

and in this greener world,

they have evolved into a myriad of different forms

Three months ago, a mother Diplodocus laid 100 eggs

in this clearing in the forest

Now they are hatching,

but there are signs they have been discovered by an egg thief

The culprit is an Ornitholestes - a two-metre long carnivore,

closely related to dinosaurs that will evolve into birds

Normally, he hunts small lizards and mammals in the forest

This is an extra treat

(Squawks)

Only 10 metres away from the carnivore,

the forest floor moves

(Squeaks)

(Squawks)

Right under the predator's gaze,

a baby Diplodocus, or sauropodlet, has hatched

Her brothers and sisters are also struggling free

from their buried eggs beneath the surface

And there is safety in numbers

The Ornitholestes is too busy eating to chase more sauropodlets

He has had his fill

A little female rests for an instant

and then, along with the other survivors,

heads for the deep forest as fast as she can

(Cheeping and squawking)

Their mother laid them at the edge of the forest

because she was too big to go deeper

But the sauropodlets need the cover of the deep forest

For the next few months, their only chance for survival

is to remain hidden from predators amongst the vegetation

Between the trunks of huge redwood trees,

the forest floor is covered in a dense layer of ferns

Beneath these,

the sauropodlets start their lifelong obsession with eating

Newly hatched, they only weigh a few kilograms,

but they must grow by one tonne a year until adults -

an astonishing 2-3kg a day

(Distant roaring)

However, the forest is not a perfect sanctuary

When faced with danger, the sauropodlets lie very still

and depend on their camouflage for protection

It may have worked this time,

but very often, the sharp-eyed predator gets his meal

Not all of the landscape is covered in forest

There are vast open fern prairies,

and this is where the titans of the Jurassic roam

Dinsoaurs like Stegosaurus,

with its distinctive row of spinal plates

(Rumbling growl)

These prairies are kept clear of trees

by the constant grazing of such giant herbivores,

and none have a larger impact on this environment

than the biggest dinosaurs of all- the sauropods

There are many different types

of these gigantic, long-necked creatures

These are Diplodocus - the longest of them all

For protection, they move in herds of 30 or more

Some older ones are over 40 metres long

They use their very strong but stiff necks

to graze over large areas with little effort

To balance their necks,

they have long tails with whip-like ends,

that are used for communication between members of the herd

Such a huge herd moving attracts an array of smaller animals

As they eat the vegetation, insects swarm around them,

and insect hunters, like these damselflies,

use the dinosaurs as gigantic feeding platforms

There is even a tiny flying reptile, or pterosaur,

called Anurognathus

that specialises in life amongst these giants

These pterosaurs feed on insects,

and spend their entire lives hanging onto the Diplodocus

They fight, feed and breed

on creatures that are 150,000 times heavier than they are

Each Diplodocus drops over a tonne of dung every day

This attracts yet more insects

especially the dung beetles

Millions of years from now, descendants of these beetles

will clear elephant dung off the African grasslands,

but their peculiar lifestyle started here

in the Jurassic with the dinosaurs

The herd of giants moves on,

carrying its own unique habitat with it

After the rain, the redwoods steam in tropical temperatures

and a dinosaur's dawn chorus fills the air

(Bellows and screeches)

A year has passed since the sauropodlets fled into the forest,

and deep in a canyon, the little female grazes

She is already over 3m long

She feeds with other yearlings,

sticking together in a creche for safety

They are here because the canyon walls drip with moisture,

creating a thick layer of moss and fern

But the canyon runs down to the prairie

and all this greenery attracts larger dinosaurs

A seven-tonne male Stegosaurus

He too is a herbivore, but very dangerous

The large plates are primarily there for display

It's the metre-long spikes on his tail that are lethal

These he can wield with devastating effect,

despite having a very small brain for his size

The creche moves down the canyon,

away from the Stegosaurus

But two Allosaurus have been drawn here -

by the smell of prey

(Low growling)

(Squeaks)

(Roaring)

(Snarling)

The Stegosaurus flushes blood into his plates,

creating a frightening display of colour

(Roars)

Confused and intimidated by the herbivore's display,

the Allosaurus backs down

Sauropodlets are small prey for the Allosaurus

These are the lions of the Jurassic -

the top predators of their age

The creche once again seek the sanctuary of the ferns,

even though, weighing half a tonne now,

they are not as well hidden as they used to be

As they grow, their teeth become more like the adults'

These are perfect for stripping ferns of their leaves

Nearby, the vast skeleton of a Diplodocus lies where it fell

Such huge, weight-bearing bones

are too large for any forest creature to remove

The female sauropodlet can have little idea

that in ten years, she will be almost as large

But the creche realise they are too near the edge of the forest,

and retreat into its green depths

Elsewhere, an adult Diplodocus herd is clearing forest

This is how they have shaped the landscape around them

Vast areas of prairies and open forests are kept that way

because sauropods flatten trees in search of food

The Diplodocus are after the ferns that grow between the trees

Their teeth are more suited to soft green leaves

than woody branches

One of the reasons these creatures are so massive

is because it allows them to have a hugely long gut

that can digest the toughest Jurassic vegetation

Whole leaves pass into their guts

where stones the dinosaurs have swallowed

help grind their food down,

so that bacteria ferment it and release nutrients

It is a process that produces a lot of excess gas

(Phwrrrrrt!)

While the gut digests,

the body is free to continue its remorseless search for food

(Squawking)

In the forest, an Anurognathus is hunting

but not for insects

He is looking for a host

He finds it in an immature Diplodocus

This is the female sauropodlet that hatched five years ago

She is now 12 metres long and weighs over 5 tonnes

She has started to develop

the spines and long whip tail of adulthood

Old predators in the forest are no longer a threat

Ornithalestes displays his long quills

in a futile gesture of aggression

(Grating squawks)

The Diplodocus have remained in a creche,

but they're getting too large for the forest

Food is short and the trees restrict them

Soon they must join the adults on the plains

There is more room by the banks of a river

that runs through the forest,

but nature is about to take charge of these dinosaurs' future

Drifting through the trees comes the scent of woodsmoke

It is a smell that terrifies every forest dinosaur

There is a huge forest fire to the south

The Diplodocus flee,

but to support their weight,

they always need three legs on the ground

So, despite the danger, they can only manage to amble

(Low howling)

The blaze, however, moves faster

and that night, a huge firestorm hits the area

(Distant howling)

Above the sound of the blaze

come the panicked cries of trapped dinosaurs

These Jurassic fires are rare, but can be devastating

Morning light reveals the bodies of forest-dwelling dinosaurs

that have perished in the flames

Three members of the creche have survived

They have been driven out onto the prairies

This is exposed territory for them

They are not large enough to repel an attack from an adult Allosaurus

To the young Diplodocus, the other dinosaurs here are unfamiliar

and huge

This is Brachiosaurus - a 13-metre high sauropod

that specialises in grazing on the tree tops

His kind can effortlessly harvest cones and fresh leaves

no other dinosaur can reach, and they have grown enormous

These adults weigh over 70 tonnes,

making them the largest land animals that have ever existed

The juvenile Diplodocus do not have the same size advantages

and urgently need the protection of an adult herd

(Wailing)

Across a conifer heathland

come the plaintive calls of the young sauropods

It is a cry adult animals are programmed to react to

There are only two youngsters now

and they need help

(Growling)

A herd of gigantic adults responds to their calls

One elderly female sizes up the two newcomers

She accepts them

They fall into line behind an adult, safe at last

The herd is at full strength

It contains a range of members - from 12-metre long adolescents

to adults three times their size

It is the mating season, and for the first time,

the female that hatched ten years ago

is old enough and large enough to reproduce

The males have started to display

They rock back on their tails to impress potential mates

Occasionally, fights break out

With creatures this size,

the forces at work during these confrontations are colossal-

enough to shatter ribs and shake the ground

(Growling and bellowing)

The victor wins the right to mate

Our female is approached by a young male

She responds to his calls first by stamping

and then generating very low frequency mating calls

This infrasound is too low for most animals to hear

He picks these signals up through the ground,

and responds by walking close to her, rubbing his body down hers

She shows she is receptive

Mating is a dangerous activity for the female

She'll carry at least an extra 10 tonnes on her back

As she has grown older,

the vertebrae over her hips have become fused and reinforced

to help her cope with this ordeal

After a few days, the Diplodocus have calmed

The female feeds on the edge of the herd,

but is not large enough to be immune from attack,

and she is unaware she is being watched

An Allosaurus knows she is vulnerable

The predators wait for her to become distanced from the herd

(Roars)

Saved by the huge tail of a larger Diplodocus

She rejoins the herd with deep wounds on her side,

but she will recover

Diplodocus can live for 100 years,

and above a certain size,

they have no natural predators

Sauropods dominate the late Jurassic

It'll be millions of years before new dinosaur herbivores

evolve to replace them

With their passing, life will never again be this large

Eventually, the mighty sauropods went into decline

Their lowland prairies became flooded

because the sea levels began to rise

This created vast inland seas

In the next programme,

we will meet the giant carnivores that patrolled them

Repair and Synchronization by Easy Subtitles Synchronizer 1.0.0.0