The Day the Dinosaurs Died Page #2

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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.

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