Dinosaurs - The Final Day with David Attenborough

66 million years ago,

Planet Earth was very different from today.

Back then, one of our closest ancestors might have looked

something like this little furry creature.

The rulers of the land were giant reptiles.

Dinosaurs.

That's one of the most infamous,

a carnivorous T-rex.

And just behind are the bison of their time,

a common plant-eater, Edmontosaurus.

But what happened to them all?

66 million years ago,

an asteroid hit the Earth,

and scientists think that it was this collision

that wiped out the dinosaurs.

But no-one has ever found direct evidence of that.

In fact, no-one has ever found the fossil of a dinosaur

that died within a thousand years of the impact.

However, a remarkable dig site promises to change that.

It's in the Hell Creek formation

in the American Midwest.

These badlands are rich in prehistoric remains…

…from triceratops…

…to pterosaurs.

And here, one patch of land

about the size of a football pitch

is yielding a collection of astonishing fossils.

The precise location is a closely guarded secret,

because this place may hold evidence…

…of one of the most dramatic events

in all the 4 ½ billion-year history of our planet.

Right, let me get down here between you.

For ten years, a palaeontologist and his team

have been trying to find out exactly what happened here.

You're at the edge of your seat every moment,

trying to dig this stuff up.

It's like trying to defuse a nuclear weapon

while you're in a rainstorm.

He's named the site Tanis,

and believes it could be a mass graveyard

of creatures that were killed

in the catastrophic asteroid strike.

A site that could reveal not only how the last dinosaurs lived,

but how they died.

If the dig team is right, Tanis could be a place

where the remains of a long-lost world

are frozen in time.

A place that gives us, for the first time,

an unprecedented window…

…into the lives of the very last dinosaurs…

…and a minute-by-minute picture of what happened

on the day the asteroid hit.

This landscape is full of fossils dating from the Late Cretaceous,

the period which began around 100 million years ago

and ended 66 million years ago,

when the dinosaurs vanished.

Palaeontologist Robert DePalma wants to find out more.

I think anybody who's ever liked dinosaurs in the past,

or still does, has thought at one point or another,

"Well, what happened to them?

"Why are they not here any more?"

So many different theories are out there,

and nobody has a tight answer to that question.

Judging from fossil evidence,

this is what Hell Creek looked like in the Late Cretaceous.

There were low-lying, marshy flood plains,

intercut by river channels and covered with horsetails,

ferns and trees.

Back then, it was warm and wet here all year round.

Tanis lies in the north-eastern corner

of the Hell Creek formation.

Instead of today's dusty prairies,

there were sandy river banks.

Instead of rocky cliffs, there were forests.

And instead of the life we know today…

…well, Robert is hoping to find out more

about what that was like.

A sandbank lying between a river and a forest

would one day become what Robert now calls Tanis.

He and his team have been digging here since 2012.

So somewhere from between there

and down here is where that came from.

It's come from up above. Hey, look at this.

What? Look.

Oh, yeah, yeah, yeah. OK.

And what they found is unexpected.

Here we've got this freshwater environment

of the Hell Creek formation,

and these shocking red, green colours

coming from the shells of ammonites, a marine organism,

kind of like a coiled snail in appearance.

So we've got this marine organism that's been thrown up

into this freshwater environment,

and they do not belong here.

How they got here is a mystery.

OK…

And there's more.

I'm just going to go ahead and plane down some of this rock.

Sitting just above the ammonites

is something that many dinosaur hunters

are desperate to find.

So this orange layer right here is composed 100%

of impact-related debris that is enriched in iridium.

Iridium is an element that's rare in the Earth's crust,

but it's common in asteroids.

The layer it's in is called the K-Pg boundary.

Dear Momma…

Oh, dear. Really? Yeah.

It's made up of dust and debris from a huge asteroid impact.

Look at that. That's amazing.

Yeah, yeah, yeah, yeah, yeah. That's what we want.

OK. So it's coming from this area here.

So somewhere within that region is where these pieces are coming from.

The boundary separates the age of the dinosaurs

from the age of mammals,

so the rocks here come from about the time

that the dinosaurs became extinct.

No rattlesnakes.

What makes the site even more exciting

is the rock layer right beneath the boundary

where Robert found the ammonites.

The rock here is really not quite rocky,

as you would expect dinosaur bones and things to be encased -

you expect really, really hard rocks and jackhammers

and things like this, but it's very, very crumbly

and it just falls apart in your hands.

As well as being crumbly throughout,

this layer of rock is also around a metre thick,

which, along with other unusual features, makes

Robert think that something very strange must have happened here.

Maybe a flood or a mud flow,

burying anything within it in an instant.

Oh, there's a beautiful… Look at that one - beautiful.

This could mean that anything he finds in this layer

would have been quickly entombed,

like the bodies in the volcanic ash of Pompeii.

Robert knows from the geology

that anything he finds at Tanis will be tantalisingly close

to the end of the age of the dinosaurs

and could be so well preserved

that it could reveal new evidence

that will bring this time period to life

in a way no-one has ever done before.

Robert digs at Tanis each summer,

the only time the weather allows him to do so.

Come on down, check out this lens over here.

In order to understand how the impact affected life on Earth,

you really need to get a very clear picture

of what the world was like right before.

That is a critical part of the story.

Palaeontologists Dr David Burnham

and Loren Gurche have been digging with Robert for years.

Oh, wow!

See… see the brown? Yep.

That might be a tubercle right there.

And it seems today is their lucky day.

Oh, my God! Look at that! Look at that.

Look, the scales are preserved!

Holy crap! Like doing a freaking dissection.

Oh, my God. Biology of Tanis.

Oh, the scale…

Look, look - the wrinkles continue down that way.

Mine's all nice and wet so far.

The scales are getting smaller in that direction.

How big are they there?

I got a… I got one with the projection over here.

What? Oh!

Yeah. Oh.

Yeah, there's the protuberance right there.

I've only seen that on one other specimen, in life. Yep.

This is the closest thing to getting to touch

a living, breathing dinosaur.

It is.

They found something extraordinary.

It is so exceedingly rare -

a piece of triceratops skin in the Hell Creek formation.

It may look like an impression in the rock,

but this is skin that has been fossilised

and, over millions of years, has turned to stone.

Triceratops bones are relatively common finds in Hell Creek,

but skin in such condition as this is very rare indeed.

The size and the patterning of the scales,

together with the age and location of the rocks

where it was found, strongly suggests

that this is from a triceratops.

The brown colour contains traces of organic material.

So it might even be possible from this

to work out which pigments were in it.

Finding and studying

such well-preserved fossils as this

helps palaeontologists build

a much more detailed picture of how these creatures lived.

Combining this information

with insights from scientists around the world

makes it possible to speculate

about what life in the Late Cretaceous

might have been like.

We know from bones

that adult triceratops could reach nine metres in length

and three metres in height.