1
Once upon a time, dinosaurs
ruled the world.
But 66 million years ago...
they vanished, virtually overnight.
So what precisely happened in the
minutes, the days, the weeks
that wiped out three-quarters of
the animal species on the planet?
Many scientists now believe it
was the impact of an asteroid
that caused their extinction.
But nobody has been able to prove it...
until now.
Evolutionary biologist Ben
Garrod and I have been granted
exclusive access to a
multi-million-pound drilling mission
into the exact point
where the asteroid hit.
This really is one of the most
impressive science laboratories
I've ever seen.
Could the team's findings
about the asteroid
finally solve the ultimate
dinosaur mystery?
This is an absolutely amazing event -
mountains the size of the
Himalayas were formed in seconds.
With Ben at the impact site,
I will be traveling across the world
to look for evidence of
the events that followed.
That is a bit of fossilized bone,
and they're everywhere,
scattered across this hillside.
It's just extraordinary.
Armed with astonishing new revelations...
Right here, we have the smoking
gun, and here, we have the bodies.
We may finally be
able to paint a picture
of the demise of the dinosaurs.
I'm off the coast of Mexico right now
and this thing you can see behind me
is a specially adapted drilling platform.
Now, there's an international
team of scientists on board
who are drilling far beneath
the seabed where we are now
to look for evidence to see why
and how the dinosaurs died.
This is the exact spot of
a huge asteroid strike
that happened at precisely the same
time the dinosaurs were wiped out.
This is Earth, 66 million years ago.
Here's the asteroid.
It's nine miles across
the size of a city.
And here's the first surprising thing -
the speed of it.
It may not look that fast at this scale,
but it was traveling an
unbelievable 40,000 miles an hour.
Seen from the ground,
it would have gone from a
mere dot in the sky to impact
in a matter of seconds.
The asteroid smashed into a shallow sea
north of modern-day Mexico,
exactly where the team
is starting to drill.
The theory goes that this impact
set off a chain reaction of events
that killed the dinosaurs.
But here's the heart of the mystery...
When you compare the size of
the asteroid and the Earth,
well, the asteroid is comparatively small.
It's like a grain of sand
hitting a bowling ball.
So how did this asteroid
cause a mass extinction
all around the globe?
By extracting rock from the impact crater,
the team hopes to find out.
So, I'm not even strapped in, and
I don't especially like heights!
But this is great, this is great.
This multi-million-pound operation
has been decades in the planning
and we're the only film
crew to have access.
Professor Joanna Morgan first
proposed the operation.
It's been a long wait.
I've been excited for, you know,
16 years, so to actually...
For it to be happening
is quite scary.
We've had so much effort between
us to get us to this point
that... that you really
want some lovely results.
Joining her on board to
co-direct operations
is Professor Sean Gulick.
So, this is the ultimate
test of some ideas, right?
We have all these models about
how the extinction happened,
but without some samples from ground zero,
we can't really test them.
This really is one of the most
impressive science laboratories
I've ever seen, and it's an amazing place -
we're going to have a quick look around.
This central area here
is incredibly important.
This is known as Main Street
by the crew and scientists.
Now, these shipping containers
are actually science labs
and, in each one...
is a whole, entire laboratory.
You can see in here huge
amounts of equipment.
This is one of the scanning labs.
But there are still lots
of personal touches.
You can see where all the
different scientists
and the rest of the crew are from.
But my hometown's not on here!
But this is the star of the show.
This huge drill will bore
through 1.5km of solid rock,
taking us back to the
time of the dinosaurs.
This is the drill bit.
Each one of these little nodules
is an industrial diamond.
We've had this one modified
with a higher-speed head
that allows us to core.
Literally collecting a column
of rock three metres at a time
and, as we go further down the borehole,
we go further back in time,
until we actually get to
the moment of the impact,
about 66 million years ago.
As Ben joins the team
drilling down into the rock
for evidence of the asteroid's effects,
I'm traveling the world to
look for clues from fossils.
My first stop, 1,700 miles from the crater,
is New Jersey.
I'm here to see a mass
prehistoric graveyard
unlike anything that's
been unearthed before.
This disused quarry
may be one of the most important
paleontological sites in the world.
I'm here to view an intriguing discovery
that may directly link the mass extinction
to the asteroid impact.
There's something very strange
about this mass extinction.
So many animals died on that day,
and yet, it's virtually impossible
to find casualties of
this devastating event.
But palaeontologists here in New Jersey
think they might have found just that -
evidence of the day the dinosaurs died.
It's such an extraordinary claim,
I want to see exactly
what they've discovered.
'I've arranged to meet
palaeontologist Kenneth Lacovara,
'one of the most experienced -
'and luckiest - fossil
hunters in the world.
'He's going to show me where
the discovery was made,
'in what used to be the seabed.'
We're going back through time.
We are. Now, if you take
one more step, Alice,
you will be in the Cretaceous.
Excellent.
'As we descend into the quarry,
we arrive at layers of sediment
'that were deposited during
the Cretaceous period,
'when dinosaurs ruled the Earth.'
So, down here, we're in
the Cretaceous period.
Here, we're in the Paleogene
period, after the Cretaceous.
'The boundary between the two
periods marks the moment
'that the dinosaurs went
extinct, 66 million years ago.'
So, this is the boundary right here.
No-one in the world has found
an in-place dinosaur fossil
one centimetre above that line.
The team uncovered a dense layer of
fossils right at this boundary line.
It's potentially a unique discovery.
Dinosaurs.
No dinosaurs.
Gosh, that's extraordinary.
'The animals found here are
typical of the late Cretaceous.'
- That's a formidable-looking tooth.
- It is, isn't it? - Yeah.
What's that from?
This is from a mosasaur.
Mosasaur's a giant marine
reptile, an apex predator.
Think of a Komodo dragon
that's as long as a bus,
with paddles for limbs,
a two-meter jaw packed full of these teeth.
We find mosasaurs here below our
bone bed and in the bone bed.
We never find mosasaurs above the bone bed
because they go extinct
along with the dinosaurs.
Ken believes that the
mosasaurs he's found here
may be some of the last that ever lived...
and that they died as part
of the great extinction event.
To understand why,
we have to look at the other fossils
that Ken has found in the quarry.
- This is incredible, Ken!
- HE LAUGHS
Look at all those fossils.
- 25,000 of them.
- SHE GASPS
The way you've laid them out in this
grid, is this as you found them?
These are the places in which
we've found them, yep.
- 170 square metres of them.
- SHE GASPS
It's an astonishing amount of work.
All these fossils occur in a layer
that's no more than ten centimetres thick.
'For Ken, the first clue
that these animals all died
'in a single catastrophic event
'is that the skeletons are largely
intact with no teeth marks on them.'
They weren't transported,
they weren't scavenged,
they died suddenly and
they were buried quickly.
That tells us that this is a
moment in geological time
that's days, weeks, maybe months,
but this is not thousands of years,
this is not hundreds of thousands of years.
This is, essentially,
an instantaneous event.
'A second clue comes from the
surprising mix of species
'that had lived in many
different environments.'
I mean, I can pick out large vertebrates.
Sure. We see the occasional bird here.
There's a tibia from a crocodile.
And that's laying next to a
piece of the outer shell
of a huge sea turtle,
something that would be maybe
a meter-and-a-half across.
'And just a few feet away,
'Ken found another turtle from a
different part of the ocean.'
This is a coastal-living turtle.
You can see how tightly articulated it is.
The shell doesn't flex, so
we know that this turtle
didn't dive deeply in the ocean.
This animal was living around the
coast, in the shallow water.
So, what do you think you've got here?
All this stuff died suddenly,
and was buried all at about the same time,
so that means all the stuff
that comes in from the coast
has to come in suddenly.
And that tells us that there is an
environmental disturbance going on
on the coastline, up-shore from here.
Whatever was the cause,
this calamity that wiped out these animals,
it was happening in the deep water,
it was happening along the coastline,
and it's happening on land.
Ken's theory is controversial,
but if he's right,
this could be the first fossil evidence
of a sudden mass death event at
the end of the Cretaceous...
right at that point in time when
75% of life on Earth is wiped out.
But what caused this mass death event?
Could all these animals have been
killed by the impact of an asteroid
1,700 miles away in the Gulf of Mexico?
Ben is with the scientists who
have been drilling into the seabed
above the asteroid crater.
I'm here, right in the middle
of the drilling platform,
and there's a fresh core about to come out.
We've already drilled through 500
metres of limestone sediment.
Now, we're going to start
to bring up rock core
for the scientists to examine as we
get closer to the impact crater.
This is the first full
core of the expedition,
we're excited to say.
The first full, three-meter-long core,
some light layers.
We're wondering if they're
ashes or something.
We're pretty excited.
This, along with other
core samples like it,
can tell the team so much information
about what was going on at
the time of the impact.
The first thing the team
does with each new core
is find out how old the rock is.
Exactly what's living,
exactly what fossils we find
tell us what age we are.
As soon as the core comes up on deck,
we are given a small crumb of material,
we take it back to the
lab and give an age call
within five minutes of the
core appearing on the deck.
I just got some sweet pictures.
Look at this crystal -
this is the same stuff from the
core catcher under the microscope.
Look at these crystals.
Though it contains valuable information,
this core isn't from the
impact crater itself.
Instead, it's from the
layers of sediment above it.
The team needs to drill a further
130 metres down into the sediment
to get to the crater itself.
The further down they go,
the harder the rock is,
so that means weeks of
24-hours-a-day drilling.
They want to pull core from
an area of the inner crater
called the peak ring,
found only in the largest of super craters.
They're formed when the
massive impact of an asteroid
forces rock to erupt in a central uprising,
which then collapses outwards to
form the distinctive peak ring.
It's these rocks that contain
the clues to what happened
in the moments after impact.
It's been three weeks since the team
started drilling into the seabed
and time and money are running short.
We didn't sample that because
it's in the middle of a core.
The drill is nearly through the
hundreds of metres of limestone
that has built up since
the asteroid struck,
approaching rock layers
from the day of impact.
I mean, look at this on the microscope.
I would say somewhere between
about 64.5 million years ago
and 63.5.
Wow.
- Wow, so this was E4...
- Yup. - ..Which is 53 million.
Now we are 63, so we have 10 million.
Yeah, that sounds like a good estimate,
- so 10 million years in three metres.
- In three metres.
We've been stuck in the
same zone for a while,
going forward very slowly,
and then all of a sudden...
- HE CLICKS HIS FINGERS
- ..boom, big jump in time.
The team are noticing clues
in the latest cores -
something extraordinary.
But as you go down, it's just
more and more and more of it.
It's got this greenish tint.
Yeah, there's one right there.
We've now had four cores
of ever-coarsening sands.
I think the only process on Earth
that can do that is a tsunami.
Tsunamis are huge, turbulent waves
that rip material from the seabed.
When the wave passes,
the material is deposited back on
the ocean floor in size order.
The heaviest, most coarse
sand settles first,
the finer sand on top.
The thicker the deposit,
the bigger the tsunami.
And the fact it's already,
like, 12 metres thick
probably already makes
it one of the largest,
maybe the largest tsunami
deposit ever discovered.
And if it keeps getting thicker
as we go, it will absolutely,
unquestionably, be the largest
tsunami deposit ever discovered.
And, of course, it's right here
in ground zero of the impact.
It's the first major clue of how
the impact of this asteroid
could have caused a deadly chain of events,
starting with the biggest
tsunami in history.
1,700 miles away in New Jersey,
Ken Lacovara has also picked up evidence
of what could have been a tsunami.
After that asteroid hit, it's
just chaos on the continent.
There are tsunami waves lapping
up against the continent.
You're going to have trees
floating down the estuaries.
You're going to have
sediment choking the rivers.
And that's exactly what we see there.
Here in our fossil bed, we get
a mixture of marine organisms
and organisms that came in from the land.
One of our more common fossils is wood.
In the Gulf of Mexico, the
crew are on the verge
of breaking into the
asteroid impact crater,
but, at the worst possible
moment, they've hit a roadblock.
So they just woke me up because there's
a problem with the drilling.
We don't know if it's snapped or
if it just got stuck a little bit.
We don't know, but they
have to bring it back
to the surface to take a look.
As they get nearer the crater,
the rock is getting tougher to penetrate,
and that's causing problems with the drill.
TOOL BUZZES
Getting to the point where
you start pushing the drill
beyond its capacity, and
right now, there's no...
There's no drilling rods, no
bit, no anything in the hole.
While the engineers fix the rig,
the scientists lose valuable drilling time.
Behind me, you'll notice
the rig is not moving.
SPARKS CRACKLE
The pump that allows it to
turn is actually broken.
RUMBLING
We're in a bit of a race against time now.
We're going to struggle
to get to 1,500 metres.
So we're all hopeful -
fingers, toes and so on are crossed -
and we'll see how this goes.
Finally, after a month of drilling,
the team are pulling rock from
the asteroid crater itself.
Already, they're seeing
evidence of the incredible heat
generated by the impact -
rock that has melted.
And look at...
In this part, it is very clear that
we have different kinds of colours,
like this red color.
It goes from green to red...
- I think it's melting the material.
- Melted... - Yeah.
- What about this?
- I think that is a big cluster melt.
That does, too. Look at that.
That looks like the suevite.
And we are now fully into
impact rocks directly,
and it's really easy to
see, because it's granite,
and so you can see these spotted,
leopard-looking big chunks.
So, in effect, you know,
these were formed, you know, on
the days that the dinos died.
Quite heavy, these, aren't they?
Yeah, you really appreciate just...
just how solid this rock is.
How deep have you gone with this so far?
We've got to just 1,330 metres, about that.
So, we were hoping to get 1,500 metres,
but we've got 700 metres
of peak ring materials,
so we're pretty happy.
Why couldn't you get 1,500?
SHE LAUGHS
Cos... cos the budget ran out.
Oh, no!
I'm dying to ask the question
that I wanted to know as a kid -
where's the asteroid?
- Yes, a lot of people think I'm going
to find the asteroid... - Yeah.
And ask me that question a lot.
Something like 95 or more percent
of the asteroid is vaporized.
- Mm-hm. - So, in fact, there's
hardly any asteroid here
beneath the surface.
The asteroid material has been, sort of,
spread all around the globe,
so it's been ejected way above
the Earth's atmosphere,
traveled round the globe,
and landed around the Earth.
After eight weeks, the work here is done.
I don't think it could
have gone much better.
I'll not forget this place.
It's been an amazing expedition,
and I expect we'll have lots more
discoveries to come.
More than 300 rock cores
have been extracted,
which the team hopes will tell the
story of how the dinosaurs died.
Four months and over 5,000 miles later,
the rock cores are now here
at the University of Bremen in Germany,
for the second phase
of this colossal and
unparalleled scientific journey.
I'm inside a huge fridge that's
now home to all the samples that
were taken up from the Gulf of Mexico,
and it's really cold in
here, as you might expect.
Now, this is to stop any
organisms from growing
and contaminating these samples.
This is a test recording. Say something.
Oh. Hello, hello.
Here in Bremen, the research team is
working to find out what happened,
minute by minute, after
the asteroid struck,
and what that meant for the dinosaurs.
OK, this is day two that
we've had the samples,
and I'm going to take you through the...
around the labs
where everybody's started their analysis.
Over here we can see people
looking through microscopes,
looking at thin slides that have
been collected from offshore.
Hi, Philippe. I'm going to film you
while you take a look at this core.
Hey!
Unraveling these cores is a mammoth task.
Over 800 metres of rock has
to be carefully split,
tested and photographed.
But what they're starting to reveal
about the force of the impact
is literally earth-shattering.
This core, from above the crater, is
what typical geology looks like -
layer upon layer of similar-looking rock,
laid down on the seabed very slowly.
This three metres of limestone took
millions of years to accumulate.
But when the asteroid struck...
it was geology at hyper-speed.
The next 600 metres of rock
were deposited in a single day,
leaving a unique and chaotic jumble.
Sean, I mean, how do you make
sense of this incredible place
- that you've got here?
- It is amazing.
This is 150km worth of core,
collected by the International
Ocean Discovery Program
- and all its predecessors back
to the late '60s. - Mm-hm.
But from all these cores,
- the most amazing is the one
we just collected... - Yeah.
- In the Chicxulub impact crater.
- Of course, yeah.
You can see this black,
flowing texture of the rock.
This is actually...
- It looks like it flowed, right?
- Mm. - You can see the textures in it.
This is actually melted basement rock,
melted granite, and it actually
takes amazing pressures to do that,
and amazing pressures to melt the rock.
This is...
So I've got a piece of what
would be considered, sort of,
normal granite, if you will -
the kind that you might
put on your counter-top,
and that's why we use it,
cos it's nice and hard.
- I mean, it... Right?
- Pretty solid.
But this... Yeah, exactly.
This stuff has actually seen
shock of an incredible level,
so think of it as pressure waves
moving down through the granite,
like lots and lots of little earthquakes.
And what it's done to it is,
all the way down at the scale of a crystal,
- is it's actually deformed it...
- Mm-hmm.
So that the final granite...
can be broken.
- It just crumbled up. That's...
that's amazing. - Yeah.
Oh, wow. Just such incredible,
amazing forces at work here.
This whole event, it's... I'm
still finding it difficult.
Well, even as a geophysicist,
where we study this for a living,
it's really hard to wrap our
brains around the enormity of
the pressures involved, and the
enormity of the destruction
- that happens in the middle of an
impact, and so quickly. - Mm-hm.
This all happened in less than ten minutes.
It's becoming clear just
how mind-bogglingly huge
the Yucatan impact really was.
And to help grasp its scale,
Sean is taking a trip to a more
recent impact site in Arizona.
This simple crater here was created
by about a 50-meter, or 150-foot,
asteroid impacting the Earth,
about 50,000 years ago.
It's about a mile across.
It's actually quite small.
It's basically, simply,
a bowl-shaped crater.
Everything above the red line
that you see there is actually
material that used to be buried
that has been flipped up on end,
and is now... or flipped upside-down,
and is now laying as a pile
of broken-up material.
By studying the shape of the crater
and the upheaval of the rock layers,
Sean, Jo and the team can
compare this site to
the Yucatan impact zone,
Even a small asteroid strike like this
would have had dramatic consequences.
So it comes in at something like 26,000mph.
10km away from here, we would
have a fireball reaching,
maybe 20km away from here, a shock wave,
and, say, 40km away from here
are hurricane-force winds,
but that would just have been a bad day
in, today, northern Arizona.
So this is what a 50m-wide
asteroid can do -
it's devastating, but localized.
But what about an asteroid
that is nine miles across
and leaves a crater 120 miles wide?
To understand the effects of that impact,
the team needs to know exactly
how much energy it released.
To do that, they're comparing
rock samples from Yucatan
to data gathered from some of the
largest ever man-made explosions.
This is the Nevada Test Site,
the most bombed place in the world.
The US military have detonated
904 atomic bombs here.
To help us understand how atomic
bombs connect to asteroids,
we've enlisted the help
of physicists Mark Boslough
and David Dearborn.
The blast must have come
all the way through,
and I bet these windows blew out.
Those shards of glass would
be accelerated by 90mph wind.
- Wind, the windows were gone. Yes.
- And they're totally... boom.
This house was part of a test
village called Survival Town,
built to study the effects
of a nuclear blast.
It actually survived a blast
called Apple-2 in May 1965.
EXPLOSION
WIND HOWLS
Most of the damage is
done by the fireball...
and the heat that is generated,
or the blast wave as it goes by...
and the houses that were
in closer didn't survive.
Those of us who work on asteroid impacts,
we naturally started comparing
them to nuclear explosions.
It's a similar phenomenon.
The experimenters had high-speed cameras,
they had gauges that measured the
intensity of the shock wave,
the blast wave in the air.
The tests found that nuclear
explosions are devastating
even at a microscopic level,
causing catastrophic shock
to minerals such as quartz.
The pressure is so high in a shock
wave from a nuclear explosion
that it actually exceeds
the strength of a crystal.
Crystal is made up of a
uniform array of atoms
and that uniformity is completely
disrupted by a strong shock wave,
and that's what shocked quartz is.
In Bremen, Professor Joanna
Morgan is looking at quartz
found in rock cores from
the asteroid impact site.
From nuclear test data, she
knows exactly how much force
it takes to shock quartz.
From this, she can tell how
much force the Yucatan rock
has been subjected to and begin
to calculate the exact amount of
energy released when the asteroid struck.
So this is a piece of shocked
quartz that we recently drilled
from the Chicxulub impact crater.
There's lots of lines here.
Essentially, the more lines
we have on the screen,
different directions, the more
shocked this rock has been.
These are caused by the impact,
by the shock wave that travels
through this piece of quartz.
So we used exactly the same
hydro-codes, they're called,
to model nuclear explosions as we
do to model the impact craters.
We've actually stolen these codes
and applied them to our simulations
of impact crater formation.
What sort of force were
we actually talking about
from the asteroid hitting it?
This event was equivalent to
about 10 billion Hiroshimas,
so, absolutely enormous.
The most dramatic event in
the last 100 million years.
10 billion Hiroshimas combined?
- That's the amount of force
going into this? - Absolutely.
It's incredible, it really is.
Finally, we have hard evidence
of just how powerful the
asteroid strike really was.
10 billion Hiroshimas.
It's a major revelation.
But the truly incredible thing
about this asteroid strike
was that it changed the face
of our planet within seconds.
And now we know that,
we can do something that has
never been done before.
'Create a simulation of exactly
how the impact affected Earth
'and the dinosaurs.'
Here's what the new results tell us
about those crucial initial minutes
after the asteroid struck.
The asteroid, nine miles wide,
smashes into the Yucatan at 40,000mph...
vaporizing instantly.
The impact makes a hole in the earth
20 miles deep and 120 miles across,
turning the surrounding sea to steam
and shattering the earth below.
Rock from deep in the Earth's crust
then rises miles into the air,
forming a tower higher than the Himalayas
that collapses to form a strange
ring of peaks that exists today.
All this in the first ten minutes.
What did this mean for the dinosaurs?
Well, it started an unstoppable
and devastating chain of events.
First, like an enormous nuclear explosion,
a radiation fireball
10,000 degrees centigrade
spreads out from the impact zone.
This searing hot sphere
fries everything within
a 600-mile radius in an instant.
The truly global devastation had
its roots not in the blast,
but in the huge vapor plume
that rose out of the crater
and through the atmosphere.
A red-hot cloud of vaporized
asteroid and rock,
expanding upwards 600 miles,
spreading rapidly outwards to
fill the planet's atmosphere.
Back then, faraway New
Jersey was covered in ocean.
And it too would soon feel
the effects of the impact.
1,700 miles from the site of the impact,
the fireball wouldn't have been visible.
That blazing, towering, swirling cloud
would've been just over the horizon,
but we might have seen a faint glow.
The animals here were safe
from the direct radiation.
Two-and-a-half hours later,
like the sound of heavy
traffic in the distance,
the shock wave, now a sound wave, arrived.
Wind starts to whip up, growing
stronger and stronger until
we're facing into hurricane-force winds.
The blast wave from the impact
surged across the Earth at enormous speed.
Its effects would have been short-lived,
but those few traumatic hours
left an indelible impression in
the earth's geological record.
These are beads of molten rock
that rained down from the skies
and as they cool, they become glass.
And if you melt rock and you cool it fast,
it doesn't have a chance to turn
back into rock, it forms glass.
Glass called spherules.
And we find these little
spherules right here
in this mass death assemblage.
What produces the kind of
energy and heat needed
to form these spherules, then?
Well, when you have an asteroid impact,
it melts the rock and it flies
up through the atmosphere
and these bits of molten rock
rain down on the planet.
'These 66-million-year-old
droplets of molten rock show that
'debris was falling on landscapes
'far away from the impact zone itself.'
Protected by the water, marine
creatures like the mosasaurs
may have been able to survive
these immediate events.
But for the dinosaurs on
land, with nowhere to hide,
this was the beginning of the end.
To show how the effects
might have played out
for dinosaurs on the ground,
we've enlisted palaeontologists
Steve Brusatte and Tom Williamson
to our international team.
They've come to New Mexico,
1,200 miles from the impact zone,
hunting for remains in one of the
richest dinosaur fossil sites
in the world.
- Yeah. OK.
- Whoa.
- Got a bone layer.
- Look at this. Check this out.
A lot of times, we'll just be
walking around in the Badlands,
looking for stuff that's
sticking out of the rock.
That's always the first clue.
This one's really sticking out.
We can tell from the shape of it
that it's part of the
backbone of a dinosaur.
It's a bone from the backbone
of a horned dinosaur.
This is probably Pentaceratops,
which means five-horned face,
two brow horns, a nasal horn and
then a cheek horn on each side.
Triceratops has three horns on its face.
This guy had two more
horns, so five horns total,
so an even gaudier dinosaur.
The ceratopsians, like
Pentaceratops and Triceratops,
were a large group of
plant-eating dinosaurs
that roamed the American landscape
for the 20 million years leading
up to the asteroid impact.
- There it is.
- Pretty good. Look at that. - Not bad.
This whole area here,
honestly, it's littered
with these kind of bones.
These were the cows of the Cretaceous,
they would've been everywhere
on this landscape.
66 million years ago, this area
would've looked very different.
Today, it's known as the San Juan Badlands.
Back then, it wasn't so bad at all.
This whole area was a lush jungle.
Dense vegetation.
Thick forests cut through
by flowing rivers.
When that day started, this whole
area here would've been teeming
with dinosaurs, and then,
about 2,000km or so,
1,200 miles in this direction to
the south-east, the asteroid hit.
And very quickly, the
dinosaurs would've realised
that something was wrong,
because there would've been
an enormous red glowing cloud
that would've filled up
much of the sky here.
The glowing cloud would've looked dramatic,
but this far from the impact zone,
the dinosaurs here would've
been safe... for now.
Now, their cousins down in Texas,
about 1,000 kilometers
closer to the impact site,
they were toast.
They were incinerated, they were vaporized.
By studying the Yucatan rock core,
we know the exact timing
of what happened next.
11 minutes after the impact,
the vapor cloud arrived in New Mexico.
The skies darkened and the
temperature started to rise.
It wasn't really a case
of fire and brimstone
raining down from the heavens.
It was more a case of all of that
stuff heating up the atmosphere
and turning the atmosphere
into a giant radiator.
The heat was so intense that,
over 1,000 miles away from the impact,
many animals would have been roasted alive.
Climate specialist Dr Brian Toon
is the first scientist ever to
theories what happened next.
A devastating global firestorm he's
studied for more than 20 years.
It wasn't falling on you, it was
60km above the ground or so,
and the glowing hot lava was
emitting an amount of energy
that's a few times larger than the sun.
This is not a normal fire.
The fire was started everywhere,
which causes what's called
a mass fire.
Mass fires can be much
hotter than a normal fire.
Well, the leaves on the ground caught fire,
leaves in the trees caught fire...
The underbrush caught fire.
There's winds at hurricane
speeds rushing into the fire,
drawing upward into the rising flames
and they consume everything.
And this vapor quickly
spread across the planet.
Probably only took a few hours
for it to reach the furthest
reaches of the Earth.
Thanks to our new model of what
happened after the impact,
we now know that fires spread
right around the globe.
But were these fires devastating
enough to cause the extinction
of all of the world's
dinosaurs in a single day?
'To find out, I'm traveling
far from the impact site
'to the very tip of South America
'and the remote wilderness of Patagonia.'
Over 4,000 miles away from
where the asteroid hit.
I am all the way down here in Chile.
Now, we tend to think of this asteroid
as being absolutely enormous,
and it was - 14km in diameter -
but in the context of
the size of the Earth,
that's like a grain of sand
impacting on a bowling ball.
And I want to understand
what kind of impact
the asteroid landing here
had on the dinosaurs
right down here at the
toe of South America.
Leading the hunt for clues is
palaeontologist Marcelo Leppe.
He's taking me to look for dinosaur remains
in a mountain valley that's
best accessed on four legs.
Marcelo, can you explain to me how
the geology of this valley works?
Actually, we are passing through time
and we are moving to the
end of the Cretaceous,
to the end of the age of the dinosaurs.
We are, at the moment,
in 80 million years ago,
this is Campanian.
So this is fantastic.
As we ride along the
valley, as we ride north,
we're riding from 80 million
to 66 million years.
Through time.
Getting closer to that extinction event.
We've reached the Valley of the Dinosaurs.
Now I want to see what sort of
dinosaurs lived here and find out
what happened to them in the
hours after the impact.
So, shall we get off and have a look?
- Yeah, let's leave the horses and look.
- Seems like a good idea.
The place is literally full of bones.
As you can see, this sunlight is the best
because the angular light
is reflecting the bones.
- Let's see if we can find a dinosaur,
then. - Yeah, let's... let's see.
Oh, for example, there.
Or here.
Look, just beside you.
- This, here?
- Yes, this is a dinosaur bone.
Oh. That's fantastic.
They're different color.
Greyish, or white.
Yeah, so what's that, then?
Oh, it looks like a vertebrae.
Probably the first one.
OK, so... yeah.
That looks like a facet, it looks
like the surface of a joint
and that would be where the skull sits.
Any ideas what species?
- Yeah, probably a hadrosaur. 99%.
- Really? - Yeah.
- That's your first hadrosaur, yeah?
- Yeah, it is.
'This valley is now a bone
bed, four miles long.'
Yes, that is a bit of fossilized
bone and they're everywhere.
Scattered across this hillside.
It's just extraordinary.
Once, it was home to herds of hadrosaurs.
Plant-eaters up to 30-feet long with
a distinctive duck-billed face.
But did the dinosaurs down in Patagonia
die on the day the asteroid hit?
Thanks to the team in Bremen,
we now know that once the asteroid
struck the Yucatan Peninsula
over 4,000 miles away,
it took 42 minutes for the
superheated cloud of debris
to reach Patagonia.
For much of the planet,
the fires triggered by the burning sky
led to total destruction.
But Marcelo has found evidence
that that may not have been the story here.
Plants that the hadrosaurs used to eat.
This is Nothofagus, the southern beech.
They're all around here, aren't they?
And if you want to see it,
look at that architecture.
And I want to show you also this one.
This is from Las Chinas,
the same valley we were
looking for the hadrosaurs.
Oh, this is fantastic.
- This is what the hadrosaurs
were walking on. - Yeah.
- And if you want to compare it...
- Well, that looks incredibly similar.
Is there actually a relationship
between this fossil leaf
and this living one?
Oh, there is a direct line
from this fossil and this one that
is living today in Patagonia.
So this is fantastic evidence
that, down here in Patagonia,
some spaces did actually make it through.
66 million years ago,
this region was warm, wet
and dense with vegetation
like the southern beech.
A species of plant that survived
the fires on impact day.
And if plants survived,
maybe the dinosaurs here
could have done, too.
Life down here should have been badly hit,
but the fossil evidence,
particularly of plant life,
is telling us a different story -
that the immediate fallout from Chicxulub
in Patagonia was not as bad as predicted.
So perhaps our hadrosaurs
had a stay of execution,
maybe they made it through that first day.
But something...
Something got them in the end.
To determine exactly what did happen
in the days, weeks and months
after the asteroid struck,
the Bremen team are still
hard at work studying rock
samples from the impact crater.
Dr Philippe Claeys thinks he's found
perhaps the most important clue yet.
So, Philippe, when this
asteroid struck Earth,
it had a massive and devastating impact.
But that didn't quite seal the
fate of the dinosaurs, did it?
Probably not. Remember, the
dinosaurs were ideally adapted
to the late Cretaceous environment.
They were the ultimate
animal for the Cretaceous.
What happened here is that
we have an incredible change
in the Earth's system,
basically kills the dinosaur
everywhere on Earth -
in Africa, Antarctica, in the
forests, or in the savanna.
But what made them extinct?
You talk about a global scale, suddenly.
- What went global? What happened?
- What went global is really
the ejection of material from the crater.
- Look at what I have in my pocket
- this is gypsum. - Right, OK.
This was part of Yucatan at the
time of impact. - Yeah. - OK?
And this material here contains sulphate.
And this gypsum affects the
chemistry of the atmosphere.
It changes it drastically.
This area's meant to be
rich in this sort of stuff.
It's supposed to be full of it.
But it's not.
We can look for the remnants of it here.
In the core, it's totally absent,
which means that almost the
entire sequence of gypsum
that was present in the sedimentary target
at the time of impact
went into the atmosphere.
This is a huge discovery.
The presence of gypsum means
the plume of vaporized rock
that spread across the world
was dense with sulphates
that blocked sunlight.
The same thing happened after the
1991 eruption of Mount Pinatubo
in the Philippines.
Sulphates reduced the amount of
sunlight reaching land by 10%,
which caused a drop in global temperatures.
25 years ago, Pinatubo had an
incredible effect on the atmosphere.
It cooled it by very little,
but it had an effect.
- And it stayed for a couple of years.
- Right.
Here, we have an event which is
orders of magnitude more important.
Pinatubo is nothing compared
to the Chicxulub impact.
It is really going global,
no place is protected,
no dinosaur can escape
the consequence of the Chicxulub impact.
This is the gypsum.
- This is what killed the dinosaurs.
- Wow.
This astonishing find is the
final piece of the jigsaw...
allowing us, for the first time,
to model what finally killed the dinosaurs.
It's what happened in the
days after the impact
that made it a global extinction.
Our blue planet turned Grey.
Long after the hot skies cooled,
ash and dust in the atmosphere
almost completely blocked out the sun.
As the lights went out,
global temperatures plunged
more than ten degrees
centigrade within days.
This is where we get to the
great irony of the story.
Because in the end, it wasn't
the size of the asteroid...
the scale of the blast,
or even its global reach
that made dinosaurs extinct.
It was where the impact happened.
Had the asteroid struck
a few moments earlier,
or maybe even a couple of seconds later,
then rather than hitting
shallow coastal waters,
it might have hit deep ocean.
An impact in the nearby
Atlantic or Pacific oceans
would have meant much less vaporized rock,
including the deadly gypsum.
The cloud would have been less dense
and sunlight could have still
reached the planet's surface...
meaning what happened next
might have been avoided.
In this cold, dark world,
food ran out in the oceans within a week,
and shortly after, on land also.
With nothing to eat anywhere on the planet,
the mighty dinosaurs stood
little chance of survival.
In Patagonia, 10% of plant
species went extinct.
The southern beeches would
have shed their leaves,
shutting down for the long winter
that the asteroid set off.
The hadrosaurs were left to starve.
The demise of the dinosaurs
down here in Patagonia
was nowhere near as dramatic as
being obliterated by a blast wave,
or drowned in a tsunami,
or even being caught up in
a colossal forest fire.
But they were doomed, nonetheless.
The dinosaurs as a group were
hugely successful and diverse,
they'd been on the planet for
more than 150 million years.
But this Chicxulub event was more
than just a local phenomenon.
It changed the climate globally,
plunging the world into
a deep, deep winter.
And there was no time to adapt.
So, in some ways,
the dinosaurs that died
instantaneously were the lucky ones.
This sudden climate change may
finally solve the mystery of
what happened in New Jersey.
As the food supply in the oceans dwindled,
shallow water creatures roamed ever deeper.
But eventually, the food would run out.
And all of those animals from
different parts of the oceans died,
coming to rest in a single layer.
It's been an incredible adventure
decades in the planning.
A multi-million-pound
scientific expedition,
weeks of drilling rock samples
from deep inside a super crater,
and months of studying hundreds
of metres of rock samples.
- So, this was E4. - Yep.
- Which is 53 million to 55.
We were just jazzed about
the science, all day long.
Many people have been up for 20 hours
and they were still just
going with enthusiasm,
describing the cores, looking
at the micro-fossils.
It was a heady experience.
All that hard work has
paid off in a big way.
The team has been able to reveal
extraordinary new details,
evidence about how the dinosaurs died.
But perhaps even astonishing than
what killed the dinosaurs...
is what happened after they were gone.
The asteroid and its aftermath
ended the age of the dinosaurs.
But as the cloud started to
clear, months or years later,
the dormant plants came back to life.
And a tiny group of animals came out
of hiding to inherit the Earth.
Creatures that would,
over millions of years,
evolve into a huge range
of different species...
Including us.
On the tip of my finger right here
is a lower tooth of
something called mesodma.
This was a little guy who was
probably about the size of a mouse.
This is one tough little mammal.
One of the very few
species known to survive
through the global devastation.
It's a blade-like tooth.
It was able to feed on things
like insects and seeds,
so it didn't have to
rely on photosynthesis.
Mammals had lived in the shadow of
the dinosaurs for 100 million years.
But now it was their turn.
This chance event that was
the doom of the dinosaurs
was a stroke of luck for
the surviving mammals.
With the dinosaurs gone,
suddenly, the landscape
was empty of competitors
and ripe with possibilities.
Just half a million years after
the extinction of the dinosaurs,
and landscapes around the globe
had filled up with mammals
of all shapes and sizes.
Fast forward another 60
million years or so,
and we have the evolution of an
extraordinary upright walking ape
that contemplates its own existence
and the demise of ancient
creatures they'd never even seen.
Chances are, if it wasn't
for that asteroid,
we wouldn't be here to
tell the story today.