Life on Our Planet (2023) s01e04 Episode Script

Chapter 4: In Cold Blood

[wind whistling]
[Morgan Freeman] 252 million years ago
and our planet is dying.
[haunting music playing]
The biggest extinction event in history
has left the world barren
and deathly silent.
[music intensifies]
But this is the story of the few
[snorts, panting]
that survived.
[music fades]
[rousing music playing]
[rousing music continues]
[wind howling]
[rousing music intensifies]
[music fades]
The start of the Triassic Period
and the rivers of fire
are gradually subsiding.
In their wake,
cooling lava covers an area
half the size of the United States
[wind whistling]
in a crust up to three kilometers deep.
[melancholic music playing]
Volcanic gases have caused
global temperatures to soar.
Forests and reefs
have been annihilated.
Hundreds of millions of years
of evolution,
Yet here,
hidden in the blackened landscape
lies opportunity.
For there is one particular life-form
that thrives on dead organic matter.
With the world an apocalyptic graveyard,
fungi were in their element.
And for a few thousand years
these simple organisms
became the dominant life-form on Earth.
But not every survivor
of the Permian extinction
relied on death for their success.
One lowly creature
found itself perfectly placed
to take over the world.
[breathes gently]
an ancient ancestor of the mammal.
This curious, pig-sized creature
was used to burrowing underground
and seeking refuge in caves,
a way of life that saved it
when other animals were dying.
Once hapless underdogs,
they are now one of the few
lucky survivors of Armageddon.
With most vegetation destroyed
by the extinction,
finding food is hard.
But Lystrosaurus are resilient
and able to forage over large areas.
[stirring music playing]
They're constantly on the move,
searching for roots, tubers,
and small pockets of regrowth.
[snuffling, grunting]
But they weren't
the only animal survivors.
Life in many forms
found a way.
Lystrosaurus's simple
but adaptable lifestyle
would reap astonishing rewards.
Facing little competition
and no large predators,
the volcanic eruptions turned it
from a bottom-of-the-food-chain burrower
[snuffling, bellowing]
to the animal that inherited the Earth.
[uplifting music playing]
In the years following
the mass extinction,
they made up three-quarters
of all vertebrate life on land,
something no other animal has ever done.
But their dominance couldn't last,
for another survivor
of the mass extinction
was on the ascent
thanks to huge changes
to the very structure of our planet.
[music ends]
For tens of millions of years,
the Earth's continents
had been converging,
creating a vast ocean
on one side of the world
and a single immense land mass
on the other,
the supercontinent of Pangaea.
[intriguing music playing]
The drying that started in a previous era
is now compounded by searing heat.
[wind whistling]
Temperatures spike to 60 degrees Celsius.
Sandstorms scour the interior.
Dunes rise over a kilometer high
gradually forming the largest
and most hostile desert
the planet has ever seen.
[music fades]
Yet on the margins
of this barren and lifeless landscape,
another group of survivors
was on the rise.
And they still dominate our deserts today.
[pensive music playing]
This is the Atacama in South America.
It's been a desert here
since the Triassic Period.
Some parts have gone decades
without a drop of rain,
yet one type of animal thrives here.
They're reptiles, supremely adapted
to this dry environment.
They have tough, scaly skin
so they don't shrivel in the baking sun.
Instead, the sun fuels them
heating their cold blood
so they can reach racing speeds.
But even desert reptiles
need to quench their thirst.
Water seeping up through the ground.
Unfortunately, these water holes
are almost as salty as the Dead Sea.
[flies buzz]
Drinking this would be a death sentence
so these lizards get their water
from an unexpected source,
an animal whose ancestors
also survived Armageddon.
Insects were hit hard
in the mass extinction,
but some made it through.
Today, these brine flies
are salt specialists,
desalinating the water,
and in the process, making themselves
into perfect little water bottles
for lizards.
The challenge is catching them.
[playful music playing]
But just when it thinks it's cracked it,
trouble on the horizon.
These prime fly-catching spots
are in high demand
[tense music playing]
and the locals do not like to share.
[energetic music playing]
[music ends]
A stalemate,
but on another lizard's territory.
[energetic music resumes]
- [water splashing]
- [music ends]
[peaceful music playing]
[flies buzzing]
The thirsty lizard seizes the moment
making the most of their distraction
no matter how brief.
The ultimate desert dwellers,
lizards are tough and resilient,
just like their ancient ancestors.
But back in the Triassic,
it was much larger reptiles
who would change the course of history.
In the four million years
since the Permian extinction
Lystrosaurus have dominated.
They emerged into an almost empty world
and have been reaping the rewards.
Life is good.
[carefree music playing]
- [adult purrs]
- [juvenile grunts]
[playful calling]
But these mammal ancestors
have had little competition or predators,
until now.
[sinister music playing]
With the planet recovering,
some reptiles have grown
to epic proportions.
This is an Erythrosuchid.
Nearly three meters long,
it's the biggest predator of its time.
Herds of Lystrosaurus are an easy target.
[grunting, snarling]
[tense music playing]
They have no defense
against this new type of reptile
or even awareness of the threat it poses.
Like a fox in a chicken coop,
an Erythrosuchid
can kill more than it needs.
- [faint cry]
- [snarling]
Lystrosaurus was the unwitting dodo
- [snarls]
- [squeals]
of its age.
A combination
of predators and competition
saw Lystrosaurus go
from total domination of the planet
to extinction.
[mournful music playing]
The mammals had lost their crown.
was the age of reptiles.
Today, there are more
than 10,000 species of reptile
although they are not all as terrifying
as their ancestors.
As the Earth has changed
[uplifting music playing]
reptiles have had to adapt
to an ever more crowded world.
And the tough, scaly skin
that allowed them to conquer
the deserts of Pangaea,
continues to be the secret
of their success.
For some, their skin has allowed them
to become masters of disguise.
[uplifting music continues]
But skin can also be used
to scare off an attacker.
Even then, there are times
when more drastic measures are called for.
[music ends]
It may have escaped the bird,
but lizards aren't known
for their swimming prowess.
Yet the anole lizard of Costa Rica
has an extraordinary survival technique.
As it exhales, it creates a bubble
that sticks to its water-repellent skin
forming its very own diving bell
and allowing it to stay hidden underwater
for up to 15 minutes.
Today's reptiles are such experts
at living in the margins,
it's hard to imagine
they once dominated our planet.
[birds tweeting]
[tense ambient music playing]
But there's a series of islands
in Indonesia
that offer a glimpse
into that very distant past.
For here, lizards still rule.
Recently hatched and already curious
this youngster is starting life
in a lizard paradise.
The only issue she has
[ominous music playing]
is her relatives.
For this is a baby Komodo dragon
and Komodos are cannibals
smelling the air with their forked tongue
to find their prey.
For the world's largest lizards
baby dragons make perfect snacks.
Luckily for her,
a nest of buried Komodo eggs
offers an easier meal.
But it won't satisfy this monster
for long.
It'll be seven or eight years
of hiding in trees
before she's big enough
to stand up for herself.
Too heavy to climb,
the adult goes in search
of something more accessible.
[fly buzzes]
A thick layer of mud
can't disguise this animal's scent.
[snorts, grunts]
Water buffalo are ever vigilant
wary of their reptilian overlords.
But buffalo calves
are not as savvy as their parents.
[suspenseful music playing]
[calf bleats]
[buffalo grunting]
[snorting, grunting]
[dramatic music playing]
- [snorting]
- [grunting]
The dragon has lost its kill,
but only temporarily.
Venom from a gland in its jaw
prevents the blood of its prey
from clotting,
leading to a dangerous drop
in blood pressure.
[somber music playing]
The result
is inevitable.
This is an echo of what life was like
back in the Triassic.
Mammals must fight for their lives,
while reptiles dominate
with a confident swagger.
But perhaps the most remarkable chapter
of that early era of reptile supremacy
was when some of them
turned their back on the land
and returned to the ocean.
[music fades]
[peaceful music playing]
Whether pushed here through competition
or enticed by opportunity
turtles went back
to the seas their ancestors left,
and today inhabit
all but the coldest oceans.
Yet once a year, adult females
must still return to dry land
to lay their eggs.
Here, on the edge
of the Great Barrier Reef
they come together in their thousands.
Aggregations like this
have been one
of nature's greatest spectacles
for millions of years.
[music swells]
There's a good reason for this gathering.
Safety in numbers.
[music fades]
Turtles first evolved
back in the Triassic.
But by the time they'd conquered the seas,
the ocean was home to deadly predators.
At eight meters long,
this is a plesiosaur.
[tense music playing]
It, too, is a reptile,
but one that spends
its entire life at sea.
[tense music builds]
[music fades]
As the plesiosaur can only eat so much,
gathering in huge numbers like this
allows many more turtles to survive.
All that remains
is to haul themselves up onto the beach
where they were born
and find the perfect spot
to lay their eggs.
[poignant music playing]
Almost two months later,
and the females' efforts are rewarded.
But each one
now has its own gauntlet to run
as they instinctively head
towards the ocean.
[ominous music playing]
[dramatic music playing]
Long before the existence of birds,
this group of ancient reptiles
made a huge evolutionary step.
They took to the wing
and became masters of the air.
Totally defenseless
this hatchling's only chance
is to carry on
ignoring the near misses,
and hoping that the pterosaurs
will be spoiled for choice.
Every lucky escape
brings it closer to the water's edge.
Yet even those that reach the oceans
aren't safe.
Only by getting to deeper water
can it avoid the pterosaurs
and escape into the blue.
[stirring music playing]
Reptiles once ruled the skies
and the waves.
But despite their supremacy,
Pterosaurs and plesiosaurs
would both go extinct in time.
[stirring music continues]
[music fades]
Yet one of the ruling reptiles
from this era has survived.
They're such perfect stealth hunters
that even after 200 million years
little has bettered them.
Oblivious to the danger
wildebeest come to quench their thirst.
[tense ambient music playing]
[crocodile snarls]
[buffalo bellowing]
But it doesn't matter.
The Nile crocodile knows
the wildebeest will return
just as they always have.
To avoid detection,
the crocodile silently submerges
holding its breath
for up to an hour.
Crocodiles can slow their heart rate
to just two beats a minute
almost completely shutting down
in a way the reptiles perfected
millions of years ago.
[tense music playing]
Yet in the moment it launches its attack
it goes from inertia
to explosive energy
in just a fraction of a second
generating enough speed and power
to launch its five-meter-long body
out of the water
all on an empty stomach
and a single breath.
It's a technique
as successful for crocodiles now
as it was for their prehistoric ancestors.
Today's crocodiles
dominate the waters they live in
but they are not
the widespread predators they once were.
For back in the Triassic,
the forces of nature
would send the story of life
in a completely new direction.
Sustained volcanic eruptions
caused another period of global warming.
[wind whistling]
As sea temperatures rose,
they supercharged oceanic evaporation.
[thunder cracking]
In northern Pangaea, moisture-laden winds
hit a 3,000-meter-high ridge
creating megamonsoonal weather systems.
And it started to rain
on a biblical scale.
[epic music playing]
[thunder cracking]
Across the planet, storms raged.
The downpours lasted
more than a million years
turning the dry deserts of early Pangaea
into a distant memory.
In the far north, torrents flowed
from high in the mountains.
[epic music intensifies]
[music fades]
Surface water rewrote the landscape
carrying with it nutrient-rich silt.
The waterways soon covered
more than 1.6 million square kilometers
an area the size of Alaska,
creating the largest delta
in Earth's history.
These fertile waterways
became the lifeblood of a new world
the fuel for evolution.
Conifers rose to the fore.
And for the first time
since the Permian extinction
our planet returned
to a forested land of giants.
[rousing music playing]
Many ancient reptiles
failed to adapt to this new landscape.
But one group embraced
this change in plant life
and would soon rise
to take over the world.
[tranquil music playing]
The youngsters start life
much like other reptiles.
They hatch from eggs
they have scaly skin
and they are left to fend for themselves
from the moment they enter the world.
[intriguing music playing]
But there are differences.
They have a much more efficient
breathing system
that continuously pumps blood
across their lungs
allowing them to run
without having to stop
to catch their breath.
[purrs, chirps]
Their legs extend beneath their body
rather than to the side
so they can walk upright.
This allows tiny hatchlings
to grow into adults
that are 50 times their size.
[soft thud]
They're part of the reptile family tree,
but are their own unique branch.
[majestic music playing]
Early giants, like Plateosaurus,
can reach the new taller food sources.
Their stomachs can digest
the tough conifer needles
and their sheer volume
helps them maintain
a higher body temperature
day and night.
It's a winning formula
that will herald a new age.
[music intensifies, then ends]
The Jurassic.
[stirring music playing]
This new dynasty would rule
for more than 150 million years.
[stirring music continues]
A reign that would see the rise
of some of the most iconic creatures
to ever walk the Earth.
Welcome to the age of dinosaurs.
[epic instrumental music playing]
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