Original subtitles

This is the story

of the largest mass murder in world history.

(dramatic orchestral music)

In the known universe, for all we know.

And these unassuming rocks are the most powerful pieces

of forensic evidence the planet has ever seen.

They convict, beyond a reasonable doubt,

the killer of almost all life on Earth;

(dinosaur roaring)

96% of everything in the oceans,

70% or more of everything on land,

at a time full of bizarre and wondrous creatures.

Sometimes, a whole bunch of things go away all at once.

That's what we call a mass extinction,

and mass extinctions beg questions.

It's called the Permian Extinction,

or the Great Dying, and it's by far the worst

of the five major mass extinctions in our fossil record.

Everything seems to die out

in a very, very short period of time.

And only recently

have scientists found the smoking gun,

a really smoky smoking gun

that brought it all crashing down.

The story of life on Earth

is an epic saga of evolution and extinction.

Turn back the clock several hundred million years

and we find many bizarre lifeforms

thriving beneath vast ancient seas.

But massive shifts in the Earth's crust

and a series of mysterious catastrophes soon produce

the first two of five major mass extinction events

that wipe out more than 75% of all life on our planet.

By the start of the Permian Period,

another massive change is taking shape,

one that will finally allow life to thrive on land.

In the Permian, the continents have all come together

to form this gigantic supercontinent called Pangaea.

You could basically walk from Cape Town

to Beijing to Boston.

Initially, most of the magic

in the Permian isn't on land.

Pangaea is surrounded by a single super-ocean.

Panthalassa.

And though much of its depths remain a mystery,

where the Continental Shelf creates shallows,

fossils reveal a world where life runs riot.

Reefs have finally recovered

from the previous mass extinction

that ended in the Devonian Period.

Coral and sponges are flourishing,

as are nautilus-type creatures called ammonites.

You would've just loved scuba diving in the Permian.

There's corals, there's cephalopods,

you still have trilobites

that had evolved back 540 millions years ago.

The lobed finned fish

that gave rise to us land-lovers have disappeared,

from the seas at least.

They've walked onto land

and into an amphibious lifestyle, like dactylic.

But new uni fish, rays and sharks, thrive.

One almost unbelievable creature, the Helicoprion,

swims in search of prey,

a shark with a circular saw of a mouth.

It basically had this whorl of teeth

mounted in its lower jaw,

and it would slam into its upper jaw

and it was a slicing mechanism.

It swam around in the sea and just chopped stuff in half

and then came back and ate it.

One of the latest saw blade fossils found,

called a tooth whorl,

points to a creature that grew to 40 feet.

It may be devoid of sea monsters,

but on land, the cool dry continent of Pangaea

breeds life of its own.

All the continents are together, right?

And so, what happens is that,

in the coastal part of the world, you have these swamps.

And in the middle of Pangaea,

because it's so far from the sea, it becomes quite dry.

And so, reptiles are favored

because they seal in their body fluids,

they lay their eggs on land, they bury them.

It'll be 100 million years

before the first true mammals appear.

But their surprisingly reptilian-like ancestors,

like these pelycosaurs with their flamboyant sails,

have already begun to strut their stuff.

What you've got are animals that look like a big iguana

with a great big sail on its back.

It's likely that these sails were for

either impressing the other sex or for moderating heat.

Placid plant-eaters like dicynodons

rip through vegetation across Pangaea with bony beaks.

They come in dozens of species,

from the size of rats to rhinos.

No doubt, many are on the meal plan

for some of the day's largest predators,

like the world's first saber-toothed carnivore,

the voracious gorgonopsid,

and titanophoneus, or titanic murderer,

at 15 feet long, one of the largest predators of its day.

And so, you had a food chain there,

plants, herbivores, predators, all living in the Permian

in relatively warm conditions on the globe at that time.

Like their prey,

these monsters were incredibly successful,

until they weren't.

(somber orchestral music)

250 million years ago

is the major, major mass extinction of all time,

when you lose about 96% of the species of life on land,

in the sea, animals, plants, forests.

Everything seems to die out, again,

in a very, very short period of time.

The evidence for the Great Dying is rock-solid.

The fossil-rich layers of the Permian,

chock full of ammonites, snails, and clams,

end abruptly some 250 million years ago.

Above for millions of years lie black blank shale,

a sign of empty, dead oceans.

The cause of the dying has been a bit more controversial.

And some people think that there was an impact

of an asteroid or comet at that time.

Some people think that it was volcanic eruptions

that caused the climate to change.

Other people think that it might be more mundane things

like sea level changing.

Then, beginning in around 2008,

things started to come into clearer focus

in a place called the Siberian Traps in modern-day Russia.

That's where our infamous rocks come in,

the result of perhaps the most devastating

volcanic event ever,

where over 700,000 cubic miles of lava

flowed from the center of the Earth,

enough to fill the Grand Canyon seven times.

Tremendous amounts of lava

coming out of fissures and cracks in the Earth

and spreading across a very wide area,

forming this huge plateau thousands of feet thick,

one lava flow on top of another

and maybe in as short as 100,000 years

or even less than that.

Scientists already knew

that these massive eruptions

occurred around the time of the Great Dying,

but have only recently pinpointed the dates.

It's interesting, we know the time

of the extinction event very, very accurately

because there are volcanic ash layers

right at the time of the mass extinction.

Those have been dated very, very carefully,

252 million years ago.

And the date of the Siberian basalts

turns out to be 252 million years.

So, could it just be a coincidence

that the biggest mass extinction

happened at the same time as this huge outpouring of lava,

which doesn't happen for tens of millions of years

between the events.

I think it's too good to just be a coincidence.

It's more like a smoking gun.

Smoking gun, that one's easy.

There's no evidence for any other trigger

for this mass extinction.

The dates line up,

the volume of volcanic rock lines up with something.

If you have that much volcanic rock coming out,

there's gonna be a problem.

And the rocks themselves

also hold clues as to just how bad it was.

Trapped inside are bubbles of gas from the eruption,

traces of the trillions of tons of carbon dioxide

that got belched out of the molten heart of the Earth

and into the atmosphere.

If you put more carbon dioxide in the atmosphere,

it's a greenhouse gas, it warms the atmosphere,

but it also causes the seas to become more acidic.

And that is gonna make it very difficult

for a creature that depends on calcite to make their shell,

because that will dissolve in low-pH systems.

(dramatic orchestral music)

It was a complete horror show.

90% of all life, wiped out,

merely a factory reset for the Earth.

The world was not a pleasant place at that time, no, no.

So, there were a lotta losers

in the Permian-Triassic Extinction.

I mean, basically, a lot of our friends

that had been with us for the entire Paleozoic,

things like trilobites, the last trilobite goes.

Lots of these earlier marine organisms,

they've survived through much of the earlier extinctions,

can't make it through.

But as always, life finds a way.

Lots of major groups still survived.

Cephalopods, reptiles, certain fishes and trees

all managed to survive the Great Dying,

and the world that they inherit is a very different place.

It is a bad time,

but thank goodness for the Permian Extinction,

'cause otherwise we wouldn't be here.

I don't think we'd be able to compete

with some of the things

that were happily living there before hand.

In the next era, the Triassic,

reptiles will expand their dominion

to rule the air, sea, and land,

along with the first true mammals.

(soaring orchestral music)

And for that, we should all be very grateful.

(dramatic orchestral music)