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