This little mammal is a scavenger.
Called didelphodon, she is a marsupial
and specializes in raiding abandoned dinosaur nests.
This evening, she could be in luck.
Unfortunately the smell of the nest
blinds her senses to danger.
It is the end of the Cretaceous period
and the continents are taking on their modern forms.
But this ceaseless movement of the Earth's crust
has also produced a surge in volcanic activity
across the globe.
Massive eruptions that have lasted for centuries
have laid waste to landscapes,
and filled the atmosphere with poisonous gases and debris.
This desolate world is still ruled by dinosaurs,
as it has been for 160 million years,
but they are nearing the end of their reign.
Life on Earth is choking to death.
Yet in the last two million years
the dinosaur's most infamous predator has appeared,
tyrannosaurus, a five ton, 13-meter long carnivore,
specifically evolved to kill other giant dinosaurs.
This is a male and he's been drawn to the foot
of this volcano by the smell of food.
The area is full of geothermal springs,
and the air is thick with sulfurous fumes.
But there is another smell mixed in here.
In one small valley there is the stench of death.
Unwittingly the tyrannosaurus has been drawn
into a natural trap.
Volcanic vents here are producing poisonous
carbon monoxide,
and because it is heavier than air,
it has formed a suffocating layer close to the ground.
The giant predator stands above the layer,
but as he puts his head down to feed on one of the corpses,
he begins to feel the effects of the gas himself.
If he topples over now, he will never get up.
Eventually his sheer size is his salvation.
As he stands up with his prize,
his head just clears the gas layer.
There are still islands of greenery between
the barren lava flows.
In the warm, moist climate of the late Cretaceous period
the vegetation has transformed.
Instead of conifers, broad-leafed trees fill the canopy.
Driving this quiet revolution among the plants
is the remarkable evolution of flowers.
Their secret lies in their intimate relationship
with insects.
This is now so close that some flowers
can only be pollinated by insects,
and some insects, like the butterfly,
can only feed on flowers.
And among these new plants the birds are flourishing,
and their calls now form an ever-present chorus.
Millions of years of evolution have also created
intimate relationships among different types of dinosaurs,
especially the delicate balance between predator and prey.
One dinosaur that specializes in defense
is the extraordinary anklylosaurus.
They are evolved to withstand attack
even from giant predators like tyrannosaurus.
At seven tons, ankylosaurus are so heavily armored
that even their eyelids are hardened.
And if that wasn't enough,
they have a formidable club on the end of their tails.
But sadly not even these magnificent creatures
have any defense against the natural forces
that are suffocating their world.
Nearby lies the tyrannosaurus nest.
These are usually closely guarded by a protective mother,
but this nest has now been abandoned,
and a didelphodon has managed to burrow into the side.
Dinosaurs are vulnerable to these mammals
because they all lay their eggs on the ground.
But size helps, and a tyrannosaurus egg
is a challenge for this marsupial.
Soon the age of the mammals will dawn,
and they will grow to massive sizes.
But at 10 kilograms,
this is as big as Cretaceous mammals get.
The tyrannosaurus embryo inside the abandoned egg
is already dead.
The scent is a lure to another didelphodon.
Many dinosaur embryos are not surviving
in this volcanic environment,
because acidic pollution is preventing
their eggshells from forming properly.
The mother is calling for a new mate.
Tyrannosaurus have huge territories
of hundreds of square kilometers.
Her challenge is to attract a wandering male.
She may have to call like this for weeks.
One of the tyrannosaurus' principal sources of prey
are these bulky torosaurus.
In the late Cretaceous, herds of horned herbivores
like these are very common and attract many predators.
It is rutting season and to display,
the males flush blood into their crests
creating vivid patters.
These displays are designed to avoid physical contact.
With one meter-long horns,
fighting can easily result in bad injuries.
The best and the brightest display crest is usually
all that is needed to settle arguments.
Occasionally showing off is not enough
and males resort to brute force.
For this old torosaurus, this was one fight too many.
He will never again challenge for the right to mate.
The mating call of the tyrannosaurus continues
to echo across the volcanic slopes,
and it has been heard.
A male tyrannosaurus has brought down
a young triceratops,
but it is not just to satisfy his hunger.
It is a gift.
Female tyrannosaurus are larger and more aggressive
than the males, and he needs to court her with food
to stop her from attacking him on sight.
The female arrives.
She is weary.
The primary weapon of a tyrannosaurus is its mouth.
It's arms are tiny so it can carry a massive jaw
and remain balanced on its legs.
This jaw can crush bone and tear off
up to 70 kilograms of meat with one bite.
The male keeps his distance.
Later that evening, they mate.
This is the first of many couplings,
as the male stays by the female while she is receptive,
ready to see off any other males that might appear.
Out on the lava flows, a group of anatatiton
wanders between islands of greenery.
These animals are members of the hadrosaur family,
the most common group of dinosaurs in the late Cretaceous.
But their kind has evolved to thrive in lush
lowland swamps, not in an ash wilderness.
Three days have passed.
The triceratops carcass has been stripped
and the female tyrannosaurus is beginning
to tire of her mate.
The male knows better than to stay.
Gliding in from the coast, a magnificent pterosaur,
quetzocoatlus is hunting for food.
This is now a rare sight.
For the last 20 million years,
these flying reptiles have been in decline.
Now these 13-meter giants are the only ones left.
And this is a dangerous place to be.
One ton crocodiles live in the lake,
and one could easily drag the delicate glider to his death.
Driven on to extinction, the skies of the future
belong to the birds that already flourish around him.
Months have passed and the female tyrannosaurus
has built a new nest, camouflaged in the forest.
Mother keeps watch.
For the full two months of the eggs' incubation,
she will not leave her station or even eat.
She knows her nest is a magnet to scavengers
like this dromaeosaur.
His cautious approach is watched by the tyrannosaurus.
She judges exactly when he has got too close.
As the sun sets another threat
comes out to haunt the mother.
With food becoming scarce, the mammals are getting bolder.
She checks the nest to make sure that more
have not burrowed in,
and then returns to her vigil.
The weeks pass, and above the brilliant volcanic sunsets
there are the tell-tale warning signs
of an even more destructive natural disaster.
Showers of shooting stars herald the approach
of a giant comet on a collision course with the Earth.
Far below, the dinosaurs are oblivious.
The torosaurus herd continues to feed.
Nervous of moonlight predators,
younger animals seek protection among the larger adults.
However, using the darkness, a pair of dromaeosaurus
try to unsettle the herd and isolate one of the youngsters.
Safe, but the predators have tasted blood
and will not give up easily.
Morning reveals the results of last night's tussle.
The little torosaurus lost his fight with the predators.
For the herd it is a blow,
too few young are being born in this polluted environment.
A didelphodon is already at the carcass.
These little opportunists are about the only animals
that are thriving.
During their long reign, the dinosaurs
have adapted to many huge changes,
but now they are facing a combination of events
that will spell their doom.
After a long trek across the ash fields,
a group of anatotitan gather around a stagnant pool
to drink and feed.
Huge batteries of chewing teeth
make short work of the vegetation.
Once again the predators make
the water's edge a dangerous place.
The group senses danger and starts to break up.
The mother tyrannosaurus has broken her fast
and she is back with a vengeance.
In the bushes nearby is the reason for her hunger.
Three tyrannosaurus chicks wait,
the only survivors from a clutch of 12.
The moment they hear the kill they start calling for food.
The mother delivers a slab of anatotitan meat.
Only four weeks old and less than a meter high,
competition is intense between the chicks,
and one is already picked on by the other two.
They will remain under their mother's protection
for at least the next two months.
Soon after that she will abandon them,
or worse, view them as food.
It is unlikely the outcast will last that long.
A few days later and the mother rests
in the warm afternoon sun.
Already there is no sign of the smaller runt.
He may well have been killed by his siblings.
Increasingly the bickering pair of chicks
are happy to wander from their mother
to explore their surroundings.
From the undergrowth, a snake watches.
These reptiles have only recently evolved
from the same family as lizards,
but already they specialize in hunting warm-blooded
creatures such as mammals.
To do this they use special sensory pits on their snouts
as a way of detecting the heat signatures of other animals.
The snake does not like what it can see.
While the chicks play they are oblivious
to approaching danger.
The mother is caught completely by surprise.
The ankylosaurus has very little brain
inside its reinforced skull,
so when faced with danger it reacts
automatically and aggressively.
Normally tyrannosaurus would retreat,
but she will not abandon her young.
The blow has cracked the mother's femur,
and ruptured internal organs.
She limps away in agony.
That night the usual evening chorus is joined
by the wimper of a dying giant.
By morning she lies lifeless on the baking ash fields.
The chicks stand expectantly by the colossal
corpse of their mother.
Hours pass and still they wait.
But their fate will now be settled
along with all the other giant dinosaurs
of the Cretaceous.
3,000 kilometers to the south,
the massive comet crashes into Earth.
The light from the impact fades in silence,
then the shockwaves arrive.
Next comes the blast front.
Finally a rain of molten rock starts
to fall out of the darkening sky.
This is the end of the age of the dinosaurs.
The comet struck the Gulf of Mexico
with the force of 10 billion Hiroshima bombs.
In the catastrophic climate changes that followed,
65% of life died out.
It took millions of years for Earth to recover
and when it did, the giant dinosaurs were gone,
never to return.
In their place have emerged other powerful
and beautiful creatures.
And we now know that one small group of dinosaurs
did survive the extinction,
and they are all around us today.
The birds.