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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 Dinosaurs.
That's one of the most infamous

carnivorous T. rex. And just
behind are the bison of that

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
1,000 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
four-and-a-half-billion-year

history of our planet.

All right, I'm gonna get down
here between you. For ten

years, a paleontologist 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 Tannis 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, Tannis

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. Paleontologist
Robert De Palma wants to find out

more. I think anybody who
has 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 anymore?

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
floodplains intercut by river

channels and covered with
horsetails, ferns and trees. Back

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

Tannis lies in the north-eastern
corner of the Hell Creek formation.

Instead of today's dusty prairies,
there were sandy riverbanks.

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 Tannis.

He and his team have been
digging here since 2012. So,

somewhere from between
there and down here is where that

came from. What did they come
from up above? What? Oh, yeah,

yeah, yeah. OK. And what
they found is unexpected. Here

we've got this freshwater
environment of the Hell Creek

formation and this shocking
red-green colour is 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. 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-P-G boundary.
Your mum-um. Oh, dear. Really?

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

Look at that. That's me.
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'd

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 mudflow,
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

Tannis 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
would bring this time period to

life in a way no-one
has ever done before.

Robert digs at Tannis 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.

Paleontologists Dr David
Burnham and Lauren

Gucci have been digging
with Robert for years.

The Oh, wow. 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, the
scales are preserved. They're

like doing a frequent dissection.
Oh, my God. The biology of

Tannis. Oh, the scale. Look,
the wrinkles continue down that

way. They're nice and wet
so far. The scales are getting

smaller in that direction.
How big are they there? I got

one with the projection over
here. What? Oh, little... Yeah,

there's the protuberance right
there. I've only seen that on

one other specimen in my
life. This is the closest thing to

getting a touch of 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 paleontologists
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.

Marks on the fossil also show
us that this one was badly scarred.

Triceratops were plant eaters.

Other fossils tell us that they
had sharp beaks and hundreds

of teeth that enabled them
to shred tough plants, such as

these cycads.

Almost all adult triceratops
fossils, including Roberts,

have been found on their
own. So it's possible that the

adults were solitary, like
modern-day male rhinos.

So they were probably
territorial, chasing rivals away.

And perhaps marking
their territories.

If you weigh more than an African elephant,
there's not much that can bother you.

Except, perhaps,
a little mammal.

Robert found these jawbones
in the fossilised burrow at

Tannis. The shape of this
tiny bone and tooth means it's

most likely come from
what's known as a pediomyid,

an early mammal,
and a type of marsupial.

Robert also discovered
fossilised nuts and seeds in the

burrow. So we have an idea
about what it might have eaten.

Robert's finds are adding to
our knowledge of the complex

world at the very end of the
Late Cretaceous. And it's not

just the fossilised creatures. If you walk
on damp sand, you'll leave a trace behind.

A footprint. The same was
true 66 million years ago. And

very, very occasionally, such
traces were preserved. And

that's exactly what
happened here at Tannis.

You know, we won't foil
the back side. Right, we'll just

plaster it on. Robert has
discovered a number of footprints.

Yeah, let's see. Looks
like a good print. Yeah.

Their shape gives him a clue as
to what might have made them.

If he's right, they were
made by a winged creature

that might well have
liked a small mammal...

for lunch.

The footprints are long and
narrow with four toe prints. Two

are slightly longer than the
others. And that suggests they

were made by... a pterosaur.

Pterosaurs are not
dinosaurs. But flying reptiles

on a different branch
of the evolutionary tree.

Male pterosaurs usually had
crests, while females didn't.

So crests may have been
used in courtship displays.

And we have an indication of
where females laid their eggs.

Because evidence suggests
one pterosaur laid hers in the

soft, sandy banks
of the river at Tannis.

And this is a fossilised egg
of a pterosaur that Robert

found there. The only one ever
discovered in North America.

If you look at it with the
naked eye, all you see is a

jumble of lines. But if you
examine it with the latest

technology, you can find out
a wealth of information. From

the chemistry of the bones,
to the composition of the shell.

And that, in turn, can tell us a lot about
how these incredible creatures lived.

Robert has been given access
to the Diamond Light Source

Synchrotron in Oxfordshire.
It's a very powerful research

tool that acts like
a giant microscope.

By accelerating electrons in
this huge ring, the synchrotron

creates beams of light many
times brighter than the sun.

Robert and paleobiologist Dr
Victoria Edgerton now want to

turn that beam onto the egg
fossil to discover more about

its chemical make-up. We're
pretty much left with the egg

of a pterosaur. We're not
lined up on the skeleton, but we

might have to move the
stage a little bit to get to the

right part. Sure. Meanwhile,
Robert can reveal the creature

inside.

And this... Who made this
wonderful thing? I got replicas of

the bones from inside that
egg, and I restored the remainder

and put together what the
skeleton would have looked like

when it hatched. That's how
big the creature would have been

outside the egg, if it had
hatched. So, this is the baby.

How big was it going to grow
out? These very long neck

vertebrae here are what really
gave part of the story away

to us, because those long
bones match very, very closely

with the Asdarkid pterosaurs.
That is the giant pterosaurs.

Oh, they were the whoppers,
weren't they? I mean, what, 25

feet? Some of them. This
probably had a wingspan maybe 15

feet, five metres. Well, it
looks as though it could take

off, really. It's easy to
picture something like that just

hatching out of the egg and
fluttering out almost like a

little bat.

They've scanned the
egg here and in America.

Victoria has the results.
So, what have you learnt from

this cyclophon image? What
we have here is a chemical map of

calcium directly within the
bones of this animal. That tells

us that these bones were
already hardened. So, it might be

ready to fly not long after it
hatches. OK. Can you see any

sign of the shell? And what
sort of shell was it? We can.

What I can show you is we
can see the rim of the egg in

sulphur. Does that tell you
whether it was a hard shell or a

soft shell? We have been
looking at this. We can see folding

occurring and this unusual
undulation. If it were a hard

egg, we would expect
splintered bits and broken bits, just

like a chicken egg. This
helps to tell us that it was soft.

So, it was perhaps like a
turtle. Absolutely. That's not the

case, is it, with dinosaurs?
Many dinosaurs then had hard

-shelled eggs. Yes. So, this
is a new discovery about those

dark-skinned pterosaurs.
Absolutely. This is something that

we are confirming for the
first time. Huh. Those flying

pterosaurs had eggs like
turtles. Yes, much more reptilian

-like than bird-like. And that
can potentially tell us more

about the environment in
which these eggs were laid. How

interesting. Yeah.

Creatures that lay soft eggs tend
to bury them in order to protect them.

So, female pterosaurs probably look
for places like canes to lay their eggs.

Because the sandy soil
here is just soft enough for the

hatchling to dig itself out.
Now, the pterosaur just has to

make sure that
the hole... is perfect.

Grr!

Grr!

Grr! Success. But it's
not over yet. Pterosaurs

had two ovaries and
they laid their eggs in pairs.

Here, on the sandbank,
sandwiched between the river and

these glorious trees, life at
Tannis seemed to be thriving.

Whoops. Never a dull moment.
But all that was about to change.

The chain of events that
led to the extinction of the

dinosaurs began in the
distant past, deep in space.

Most scientists think
it all started in a ring of

dust, rocks and debris
known as the Asteroid Belt.

It's usually an
uneventful place.

But it's thought that
many, many millions of

years ago, a rock was
bumped into a new orbit.

And diverted on to a collision
course with planet Earth.

Robert is building a vivid
picture of late Cretaceous life

at Tannis. And the team have
found a way to find out some

more well-preserved footprints.
So these are animals that

were actually walking in the
water? These guys would have

been essentially on a mushy
riverbank going down to drink

at some point. Animals tend
to congregate around the rivers.

This print is 30 centimetres
long. So I think this is from

a type of dinosaur that we
call a duck-billed dinosaur. And

they would have been very
common in the Cretaceous. They

ate the plants in the area
and they got very large, 30 feet

long. And there are more.
This track, you see all the toes

are very well-preserved.
You even see a nail print at the

tips of the toes. So the little toenails
dug into the mud. I love this one.

This is Robert's prize
footprint. It has three toes. And

it's longer than it is wide.
So it's very likely to be a

carnivorous dinosaur. It's
so well-preserved that you can

see the mark left by its
sharp claw there. Hell Creek is

well-known for one carnivore
in particular, T. rex. This

footprint is too small
for an adult T. rex. But it's

possible that it was
made by a young one.

Robert also found this at
Tannis, the crown of a tooth. Its

shape and its serrated edge
are indications that it comes

from an adult T. rex.

contarien

Bite marks found on T.
rex bones show that they ate

other T -Rexes. And a youngster
would make an easy catch.

But not this time.

Very few footprints are
preserved as fossils in Hell Creek.

So if you find several in one
place, as Robert has done,

it's a reasonable assumption that there
would have been many more nearby.

And that supports the idea
that dinosaurs and pterosaurs

were thriving at Tannis
shortly before the impact.

And if they were thriving...

they must have been reproducing.

Fossils from dinosaurs
similar to T-Rex show they

may have laid around
20 eggs in a circular nest.

It's possible that,
like crocodiles, they

partly covered their
eggs to keep them warm.

For one T-Rex, a misfortune

and one T-Rex, a disaster was looming. But
for all dinosaurs, a disaster was looming.

It was approaching.

Its journey would take it through the
orbit of our neighbouring planet, Mars.

Had the two collided, a catastrophe
on Earth would have been avoided.

But it was not to be. And
Earth's fate was sealed.

As Robert's dig continues,
his vision of what happened at

Tannis is finally starting to
come together. It seems the

sandbank was full of life.
T-Rex, Triceratops, little

mammals, alongside the
footprints of other dinosaurs and

pterosaurs, all in a very small
area. See the scales? I do.

Oh, my God. That excites me,
just looking at it. Then Robert

finds something
truly remarkable.

See the cracks already forming?
Look at that. So we're going

to have to really monitor
that before we glue it. Because

this is getting vulnerable now.
An almost complete creature.

To get this block
out, we're freezing it.

Robert is about to
attempt something tricky.

Steady. Let's go. To get
the fossil out in one piece,

they're trying to freeze it
using liquid nitrogen at almost

200 degrees below zero.

Watch the footing. Lorne,
I'm worried about brittleness

here. Sure. Get that hammer.
Give this a couple of whacks

with the hammer. OK. Move
over five centimetres. Good.

It's cracked loose. Yep.
OK, it's loose. So we have to

get this out in one piece.
One, two, three. Yee-haw! Total

success. Total success.
This is a technique used in

archaeology for digging up
human remains. We've got enough

time to work with the fossil and not
damage it. And I couldn't be happier.

And the creature
Robert found... a turtle.

This is the fossil. Now it's
been cleaned up. It's lying on

its side. Here's the outline
of its shell. The shape of the

shell and the scorched edges here
tell us that this was a bayonet turtle.

Robert's bayonet turtle
looks very similar to modern

cooter turtles and lived in
the same sort of freshwater

environment.

For a turtle, tennis
would have been ideal.

It would have been
warm, shallow water...

...plenty to eat...

...and lots of safe places in which to
warm up in the late Cotacean sunshine.

The turtle fossil Robert found
is almost complete. This is

the underside. And this brown
material up here is fossilised

wood. It's the end of a stick
that passes right through its

body and comes out just here.
So the evidence points towards

this turtle having been impaled.

A violent end to one of the
many creatures found in the

crumbly rock layer at Tannis.
When I look at the animals and

plants preserved in the
sediments of Tannis and the

footprints beneath it, I
see a picture of a vibrant

ecosystem, many different
dinosaurs, and a thriving, thriving place.

After ten years of digging,
there is now enough evidence to

piece together much of the
story of Tannis and the creatures

which lived here.

Robert has found so many
fossils, it looks as if even at

the very end of the late
Cotaceus, Tannis was bursting with

life. Full of the giant
reptiles that had dominated

the planet for more
than 150 million years.

It's impossible to know how much
longer their reign would have continued.

Because all this
was about to end.

The asteroid hit...

...in what is now the
Yucatan Peninsula in Mexico.

It's called the Chicxulub
asteroid after the

town nearest to the
centre of its crater.

Any living thing within 900 miles of
the impact... ..was destroyed by the blast.

But what effect did the impact have
on Tannis nearly 2,000 miles away?

To find out, Robert is
looking for clues that might

link Tannis to the actual
day the asteroid hit.

We've got some wood and
pressed up against this, and all

intertangled, we've got the
carcasses of fish. OK. That's a

beautifully preserved tail,
so that fish is going to be

absolutely fine. Absolutely
gorgeous. So part of the detail

work that we're doing right
now is going in and checking out

all the individual elements in
this mass death layer. Some

of the evidence he's found so far has
been hidden inside the fish themselves.

In more ways than one, it
literally is an operation of a

Cretaceous fish, so we're
performing surgery on this thing.

Robert needs to open this
fish's skull. And very carefully,

we want to separate this
from the rest of the fish. OK.

There we go. Opening up the
fish. Got a nice ant that made a

home in there. And beautiful.
Look at that. OK, here we have

the gill bars of the fish.
Those are the bars that hold the

filaments of the gills. And
between the gill bars, all of

these clusters of round
objects, those are the

ejectospherules. Ejectospherules
are tiny balls that were

once molten rock. They could
be evidence of what Robert

suspects, that creatures
here died on the day of the

asteroid strike. Those
ejectospherules last saw the light of

day when they were flying
through the air 66 billion years

ago.

After a large asteroid
impact, a mix of vaporised

and molten rock is
propelled into space.

There it cools, solidifying
into tiny glass droplets. Some

carry on deeper into space.
But what is the result? Most are

pulled back to Earth by gravity.

After a major asteroid hit,
trillions of ejectospherules

would fall from the sky.
Then, over millions of years,

pressure and chemical
reactions in the ground would turn

most of them to clay. They'd
look something like this. So,

finding spherules in the
gills of a fish, as Robert has

done at TANIS, suggests the
fish sucked them in while the

spherules were still
falling. So, these creatures

could have died at the
time of an asteroid impact.

Once Robert begins to look
for ejectospherules, he finds

more and more and realises
the thick crumbly layer of rock

at TANIS is full of them.

I mean, this stuff is... Oh, my
God, look at that one. These

things are just gorgeous.
Ejectospherules like this give us

a fingerprint of where they
came from. If these spherules

were connected to the
Chicxulub impact, then the whole

crumbly layer could be full of
evidence of what happened on

the day the asteroid hit.
That's a good one. Oh, is that a

droplet right there? To see if
that's the case, Robert needs

to find a spherule that hasn't
turned to clay. Oh, my God,

that's a beautiful droplet.
OK. The small pieces of orange

material that Robert and
Lauren are digging up may be able

to help. There, amber. If there
was anything flying through

the air at that time, this
is where it's going to get

caught.

The amber they're collecting
was once sticky resin oozing

out of a late, cretaceous
tree trunk. It's a way for the

tree to protect itself, like
a scab forming on a cut.

Anything covered by the resin would
be frozen in an amber time capsule.

If they find a spherule
preserved in amber, it could be

analysed to see if it comes
from the Chicxulub asteroid

impact. The spherule is a
very important part of the

asteroid's history. So,
during this batch, we were

incredibly lucky that we
came across two completely

unaltered spherules. This
spherule could be something

amazing. Evidence preserved well
enough to analyse for chemical clues.

If so, it could link
tennis directly with the

Chicxulub impact and the
last day of the dinosaurs.

It's a very important part
of the asteroid's history. To

investigate, Robert is joined
at the Diamond Light Source by

Professor of Natural
History, Phil Manning, of the

University of Manchester.
They've already run initial tests

on the spherules in America.
What have you found out so far?

These little glass spherules,
these globs of molten material

from the impact site, have
a chemical signal that ties it

with where they came from.
Because when an asteroid hits, it

melts the ground that it
hits, but also that glass has a

little bit of contamination
from the asteroid itself. And

that gives you a unique
geochemical fingerprint. We can see

once we've scanned it and
looking at spherules from other

sites in North Dakota, we
can get a baseline for what the

ejector should look like when
it's related to the Chicxulub

crater. You can see each
element here and the ratios of

those elements. And when
we look at tennis, it's a match. I

mean, it perfectly overlays.
So I think this is powerful

evidence supporting that
tennis and Chicxulub are linked.

And what do these findings
mean for the rest of the fossils

that you're finding in
tennis? This data is key for the

entire site because once you
have that link and you know

what impact affected tennis,
then you essentially know that

every object in that site, all
the animals and the plants

and everything buried in those
sediments, are linked to the

last day of the Cretaceous.
And the synchrotron here

in the UK reveals something
even more remarkable.

So this is showing a beautiful
synchrotron scan of a half

of one spherule. The glass is
a good geochemical fingerprint

and we've got calcium, some
iron, we've got strontium. But

when we look at the entire
thing, we see something quite

unexpected. That's your
entire spherule. What's this? In

this, we've got a little bit
of a nugget. There is a little

particle right there. So
we scan it and that's a lot of

iron in there. Over here, we've
got chromium, a big peak in

chromium. Over here, we've
got a big peak in nickel. And the

abundances of iron, nickel
and chromium all together, that

matches what you would
expect to see in a meteoric body.

That does not match what you
would normally have down here.

So this is extraterrestrial
material. If you were to sort

of grind up and stuff into a
spherule, a piece of meteorite,

that's what it's going to look
like. This could be a piece

of the Cheechaloobe asteroid.
The piece of the bullet that

killed the dinosaurs? No.

Robert could have found a
fragment of the asteroid itself

in Tannis. Physical
evidence linking this site to the

Cheechaloobe impact. But
Tannis is almost 2,000 miles away

from where the asteroid hit.
So exactly how did it cause the

creature's deaths?

To answer that question, Robert is
searching in the mass death layer.

Right here, we've got this
intertangled mass of fish.

There's one fish here,
another sturgeon goes this way,

underneath the body of a
paddlefish. There's another

sturgeon that goes this
way, underneath this log, and

continues out the other
side. And his head hit that

log and has deflected
downward at a 90-degree angle.

Robert uncovered a tangled
mass of fossilised creatures and

logs surrounded by spherules
and crushed together in what's

known as a log jam. He has a
theory that the creatures were

swept to their death in some
kind of turbulent surge of

water and quickly entombed in
sediment, which is why they're

so well-preserved. But what
could have caused the wave?

One theory is a tsunami.

The asteroid hit at sea.
Recent studies show

it may have caused the
wave almost a mile high.

The height of the wave would
have gradually reduced as it

spread across the oceans.
In the late Cretaceous, North

America was divided by a
narrow sea that's been called the

Western Interior Seaway. The
tsunami could have travelled up

this towards Tannis.

But the wave was so high
that it was almost impossible But

there's a big question about
the tsunami idea. The timing.

Oh, which fish is that? It's
a new contact. If a tsunami

killed the fish, it would
have to have hit while ejector

spherules were falling. Because
spherules were found in the

fish's gills. So, how long
after impact did the spherules

arrive at Tannis? Pretend
this ball of foil is a piece of

ejector coming out of the
crater. It would then go on an arc

path, ballistic trajectory,
out of the crater and to

wherever it lands, in this
case, Tannis. If we know the

distance between myself and
the landing site and if we know

the size of that ball, we can
accurately calculate how long

it would take to get there.

The result is surprising.
Robert and his team calculated

that these ejector spherules
landed at Tannis between 13

minutes and two
hours after the impact.

If a wave killed the fish, it must also
have reached Tannis within two hours.

Data from recent tsunamis show
even a small amount of damage

but a powerful one would
take much longer than that to

travel almost 2,000 miles
from the impact site to Tannis.

So, if it wasn't a tsunami,
what could have caused a surge

of water at Tannis?

Professor Stein Bondovic
is an expert in tsunamis.

The fjords in Norway are
very special. We have tall

mountains surrounding
bodies of water, so the water is

usually very calm. In 2011,
something very strange happened.

The water in the field began
to move violently. The height

of the water increased by
one and a half metres, like a

maelstrom with turbulent
water. Someone said that the fjord

was boiling. News
started to roll in. There'd

been an earthquake
5,000 miles away in Japan.

A journalist from the local
newspaper called me and he said

that people were observing
waves here in the fjords. I got a

video clip of the waves. I saw
immediately that they looked

like a tsunami wave. So, later
in the afternoon, you can see

that the fjord is perfectly
calm. But at the beach here, you

could see that the water is
sloshing back and forth. And no

-one had ever seen anything like it.
Some people got very upset and afraid.

A magnitude 9 earthquake had devastated
the north-east of Japan around Fukushima.

But how did that affect a
fjord so far away? So, no-one in

Norway could feel the
earthquake. But I could see that the

time matched the arrival of
the waves here in the fjord.

Eventually, Stein and his team
realised that this might have

something to do with seismic
waves, shock waves that pass

quickly through the earth
during an earthquake. So, it took

only 12 minutes before the
first signal of the earthquake in

Japan reached all the way here
to western Norway. So, it was

the seismic waves that caused
the earthquake. The waves that

caused the normally calm
water in the fjord to slosh

turbulently back and
forth. Just thinking of that,

scientifically, it's fantastic.

Could something similar have
happened in Tannis? The large

weather currents can be through
the orange waves. Trying to

find out is geophysicist,
Professor Mark Richards, who's

been studying the site at
Tannis for several years. He's

working with Robert to discover what
could have caused a surge of water here.

A tsunami can't get here in
less than a minimum of 12 hours.

But seismic waves travelling
from the Yucatan impact site to

North Dakota can
arrive here fairly quickly.

In the late Cretaceous, the
western interior seaway that

divided North America could
have been connected to Tannis

through a sea wave.
It's a system of rivers.

If you have a very large
body of water, like the western

interior seaway, and you can
shake it back and forth, you

can generate a large water wave
coming up this river at Tannis.

So, seismic waves from the
impact could have caused surges

of water in the Tannis River
system. Seismic waves get here

quickly enough, coming up
the Tannis River, inundating this

area, arriving at the same
time these spherules are still

falling out of the air.

The mystery of the wave and
the thick layer of crumbly rock

has been solved. Seismic
waves travelling through the earth

could have caused powerful
surges of water at Tannis.

Possibly carrying mud
and marine creatures like

ammonites from the
western interior seaway.

Dumping them on the
Tannis sandbank and burying

everything at the same
time as spherules fell.

Over millions of years, the
mud would turn into the layer of

crumbly rock. And that's the
beauty of Tannis. What you're

seeing is a deposit that is
literally recording the last,

say, 45 minutes to an hour
and a half of the Cretaceous.

If the extinction of the
dinosaurs was a crime, the

detectives solving it would
have plenty of evidence. They

would see that the asteroid
was in the right place at the

right time. They would see
that no dinosaurs survived after

the hit. They would have a
piece of the murder weapon, a

fragment of the asteroid. But
they would be missing one very

important thing. A body.

No-one has ever found the
fossil of a dinosaur that was

killed by the effects of the
asteroid impact. But Robert did

find part of a triceratops in
the crumbly layer at Tannis.

So could that be the remains
of a dinosaur that died on that

day? I'm still dubious about
the horn. I kind of want to

keep the horn in the jacket.
I think if you took it off, at

least take this section and
see what's going on under here.

To find out, the team needs
to establish cause of death,

which can be difficult when
you only have a piece of skin

and a horn to go on. This is
the horn after they'd cleaned

it up. The team is particularly
interested in these lines

here. And they found that the
fractures go right through the

horn. So rather than dying
as a result of the impact,

they wondered whether it
had been killed in a fight.

But when they looked at the
fractures in more detail, they

found signs of new bone
growth here. An indication that the

bone had started to heal.
So it looked as though the

triceratops survived the
event that broke its horn.

Could this triceratops have
survived until the day of the

impact? The team found
evidence, including sagging in the

skin, which suggested that
there was decay underneath. That

means its body had started to
rot before it was entombed and

preserved by the surge.
So it seems that this dinosaur

didn't die as a result of the
asteroid impact. Perhaps in

the months before the
impact, the broken horn put

the triceratops at a
disadvantage over its rivals.

And that might have
led to starvation.

ROCK MUSIC PLAYS Robert
has still not found direct evidence

of a dinosaur that was killed
by the asteroid. We've got all

these bones on the ground
right now, But the one thing that

we would just dream of
finding is that one dinosaur that

died on the day of the impact.

And the weather isn't
helping his search.

Oh.

That theropod's print is
toasted. Yeah, it was in a low

corner. It's full of mud and
water. The problem is it's wet.

Look, see, if we're not
careful, we're going to lose the

print. And that's the biggest
theropod print we've got. I

see some areas that could
use glue right now, too.

The team is racing to excavate
the footprints, along with

dozens of fish fossils tangled
together in a log jam before

storms wash them away. We're
up against the clock here. The

stuff that could be exposed
right now is going to get ruined

by the rain.

But then Robert comes
across something that looks very

unusual. That's my god. What
is going on right there? Are we

sure this isn't a crocodilian?
That's not a crocodilian. No.

I'm going to try this piece
right here. I'll go in from the

top and then twist up and
it separates on, right on that

line. Oh. That's skin right
there. That's actually scaly

skin. No, no, no, no, no.
Look, look, look. Look at that

pattern right there. Have you
ever seen elongated scales

like that before, Dave?
Scudalates and birds. Just careful.

Oh, my god. That's changing
again. Oh, my god. We're seeing

it for the first time in 66 million years.
I think we've got ourselves a dinosaur.

A dinosaur fossil. And
unlike the triceratops, this is

located in the log jam, the
mass death layer, surrounded by

the fish with
spherules in their gills.

This is the most incredible
thing that we could possibly

imagine here, the best-case
scenario. We're excavating this

mass death layer of fish
from the surge sent up by the

impact, and we've got dinosaur
remains. The one thing that

we would always want to
find at this site, and here we've

got it. This is unreal. I cannot
process this in my brain. I

am absolutely blown away
by this. Just my heart is literally

pumping out of my chest.
Wondering what is behind there,

just a couple of centimetres back in the
outcrop. What is waiting for us back there?

The team keeps digging. The
scales get big again over on

this side. So this could be
a rib cage. It could be laying

against ribs that are curved.
There's something here. That's

hard. That's bone right
next to the skin. But that's an

articular surface right there. So this
is either a hip or a shoulder element.

After hours of
painstaking work...

And we can go from the
thigh of the animal. There's the

knee, and then you've got
the little calf muscles of the

dinosaur over there bulging
out, and you go down to the

ankle bones. And these are
the toes of the feet. We've got

nails at the tips of the toes.
It's a beautifully preserved

leg, all articulated, covered
with skin. The complete leg of

a dinosaur. In my wildest
dreams, I never expected to find a

dinosaur leg in this deposit.
I mean, and then it's got skin

and tissue. It does look
just like a drumstick. It looks

like a Thanksgiving turkey
just laid out in the ground. And

this weird scale pattern on
the thigh of the animal, which

we've never seen in a dinosaur
before. Well, Thesiosaurus

don't have any form of
defence, so they have to have

camouflage or something.
That's a good point. So this could

have been some sort of
camouflage marking. Robert thinks he

has found the body in question.
A dinosaur that might itself

have witnessed the
cataclysmic impact.

Dinosaur fossils are not
known from the last years of the

Cretaceous, and it was unclear
whether they were already

extinct or in decline or what was
going on, so they were just sort of absent.

And this answers that question,
were dinosaurs still there

then? Well, yes, this one
likely died in that search.

For such big claims,
Robert needs verification.

He's brought the dinosaur
leg to London to get a second

opinion. And then here are the
pads of the toes. You can see

all those beautiful scales
lined up. From Professor Paul

Barrett, an expert in
Ornithischian dinosaurs from the

Natural History Museum. So
what do you think this might be?

When we look at the leg, it
has claws, like the claws we see

in small, agile, bipedal,
running dinosaurs that are plant

eaters. We can rule out
things like triceratops, partly just

because it's not big and
stocky. And the proportions of

those legs are also different
from some of the other plant

eaters we see, in that they
have this rather long ankle and

shin compared with its thigh
bone. So as we narrow those

possibilities down,
what we're left with,

probably, is an animal
called a thesilosaur.

Thesilosaurs lived next to
rivers where there was plenty

of rich vegetation to feed
on. They had leaf-shaped teeth

common amongst
herbivores and claws on their

short front limbs.
Excellent for digging.

They were also known
as the thesilosaurs.

But how did Robert's thesilosaur
die? Could it have been

killed by another dinosaur?
It's a possibility. This is a

relatively agile animal. And
that turn of speed would have

been its primary defence
against the large predators living

alongside it. So,

to escape a hungry
T. rex, a thesilosaurs'

first line of defence
would have been to run.

But it may have had
another defensive trick.

Living next to rivers, it's possible
thesilosaurs were able to swim.

It doesn't seem to me like
there is any evidence that this

animal was predated. None
of the obvious tooth marks or

leftover bits of carnivore
teeth to suggest it's been

eaten. So, how do you
think it died? It didn't have any

particularly nasty diseases
when it died. As we can see,

the bones look OK. So, this
is an animal that was probably

living and healthy at the
time that this happened to it.

Could this be a victim of
the meteor strike? I think it's

entirely possible. This is
actually a shoulder bone. And

this bone in the living animal
would actually be way over

here. And similarly, this little
bone here would have been

from about maybe a third of
the way along the tail, maybe

halfway down. So, somehow,
these two bones have been

telescoped together. So, maybe
this animal has been tumbled

around. We've ruled out a
lot of other possible causes of

death for this animal. So, it
could well be that this is an

animal that was there, being
tumbled around in its death

throes in that river as a
result of the asteroid impact.

Well, it is exactly analogous
to those human bodies found

in Pompeii. It's very
similar in terms of that quick

entombment. Yes. And it's
almost as evocative. That's

absolutely true. You've got
literally the blink of an eye at

the end of the Cretaceous
snapped up into

history, and there it is
ready to be dug up. Wow.

After years of investigation,
Robert has found out a great

deal about the creatures which
lived at Tannis. And he knows

that many of them were alive
on that fateful day when the

asteroid devastated our
planet. But how exactly did they

die? Robert's findings show
that Tannis was a very dangerous

place to be. These kinds of
findings now allow us to tell

the story of that day and
finally answer that question.

One of the most important
days in Earth's history

probably started much like
any other late spring morning.

We know the season because
Robert found fossils of young

fish that died at the size
they reach at that time of year.

This agrees with evidence
already found by other scientists.

Perhaps this day that
would end with so much

death began with something
different. A new life.

No-one can be certain of the
exact timings of the day when

the asteroid collided with
our planet. But it's estimated

that within just 40 minutes of
the impact, the consequences

for the creatures of Tannis
would have been profound. The

asteroid collided with our
planet Based on Robert's finds

and the latest evidence from
other scientists, this is how

the catastrophe
might have unfolded.

The asteroid is around seven
miles across, bigger than Mount

Everest, and travelling at
close to 45,000 miles an hour.

The impact causes an explosion bigger
than a billion Hiroshima atomic bombs.

At Tannis, almost 2,000 miles
away, it's completely silent.

But at the impact site,

the asteroid vaporises.
More than three trillion tonnes

of rock are ejected into
space in a blast of superheated

violence.

Winds higher than 600
miles an hour. A colossal

earthquake, followed by a
ring of massive tsunamis.

All the while, the creatures at
Tannis go about their business.

Just like any other day.

The evidence suggests that
baby pterosaurs emerged from

the egg, ready to fend for
themselves. And that includes...

flying? Well, almost.

Elsewhere, as the devastation
spreads out across North

America towards Tannis,
dinosaurs and creatures of all

shapes and sizes are
obliterated by the blast.

The Tannis is the
largest planet in the world.

At Tannis, for a few
more precious minutes, life

carries on as usual.
But the clock is ticking.

The blast from the impact never reaches
Tannis. But seismic shockwaves do.

They are far more powerful than
any earthquake ever recorded.

The Thessalosaur might
head for a place of safety.

But seismic waves are
now slowly shaking the

whole region, causing
water to slosh and churn.

At Tannis, the Tannis is the
largest planet in the world.

Strange currents in the
river give a hint of what is still

to come.

Next, it begins to rain. Ejectors
ferules are falling back to Earth.

As the ferules begin their fall,
friction heats them until they're red hot.

Then the heat transfers to the air.
Temperatures rise with every second.

As the heat builds, the creatures
of Tannis are fighting for their lives.

And then, as seismic waves continue
to slowly rock the whole region...

a violent surge wave, 10 metres from Earth,
rises high, rushes up the Tannis River.

Surviving the turbulence of the surge is
a challenge even for the best swimmers.

Then, the powerful
rocking of the river system

slowly begins to draw the
water back the way it came.

Swimming may have saved the Thessalosaur
in the past, but not this time.

A large, robust animal like a
T-Rex might have survived the surge.

As might a hard-shelled
reptile. But there is much more to

come as billions of tonnes of
superheated ferules continue

to fall, the atmosphere
gets even hotter,

igniting dead leaves
and sparking wildfires.

Earthquakes. Fire. Devastation.

Little would survive
for long... on land...

or in the air.

As the air reaches the
temperature of an industrial oven,

those that live deep underground
may have a better chance.

As the slow sloshing of
the river system continues...

another powerful surge hits.

TANIS There is no
escaping the destruction.

For many of the creatures of
Tannis, Their stories end under water.

In less than two hours, the
world has changed forever.

The mud the surge waves
leave behind will gradually turn

into the thick layer of crumbly
rock entombing the creatures

which died here.

Until 66 million years later,
when they're finally unearthed.

Robert's finds have helped
us understand in remarkable

detail what happened at
Tannis in the minutes after the

asteroid impact. But what
about the rest of the world?

The impact triggered catastrophic
events such as earthquakes

all over the planet. And
as ferials continued to fall,

wildfires may have
sprung up around the globe.

As that horrific day drew to a close, many
of the world's dinosaurs were already dead.

Research shows that the
angle at which the asteroid hit

and the sulfur-rich rocks at
the impact site amplified the

devastation. Billions
of tons of sulfur were

ejected into the atmosphere,
blocking the sunlight.

Without light, most plants died
and food became scarce. As

the weeks and months passed,
any dinosaur left alive would

have died of hunger.

In the oceans, it was the
same. Nearly all of the world's

plankton disappeared,
leading to the starvation of most

marine creatures. It's thought
that the nuclear winter that

followed caused a global
temperature drop of at least 25

degrees centigrade. The
fossil record tells us that this

huge change in climate marked
the disappearance of three

-quarters of all species,
including the dinosaurs. The

planet was in semi-darkness
for around a decade, as dust and

soot slowly fell to Earth. But then came
something wonderful. A new beginning.

Once the dust cleared from the
atmosphere and the sunlight returned,

plant life was gradually
restored. Led by ferns, the spores

of which had lain dormant
deep underground. And the world

began to turn green once more.
But what about the animals?

Back at Tannis, Robert has
unearthed something that could

have helped save some of the
creatures from the devastating

fires. We saw a little thing
poking out, so we kind of

followed it back. And I'm so
glad that we did, because what

we have here is a fossil
burrow from an animal 66 million

years ago. The only animals
that would have been around back

then that would likely build a
burrow like this would be the

small mammals, roughly
ferret-sized, and also some reptiles.

If it is from a mammal, this
is sort of a window into the

lifestyle of some of our oldest
ancestors out here. This guy

would have burrowed sideways
right into the riverbank. We

actually have some scratch
marks on there from the interior

when they were digging it,
going back, and he would have

lived back here and sought
shelter from the dinosaurs,

because they just did
not want to get eaten.

Burrows are part of the reason
that mammals survived the

great extinction. During the
nuclear winter, a burrow would

have provided warmth,
protection, and a place to store food.

Mammals that survived were
resourceful omnivores, and

insects would have been
a plentiful source of food.

And they had another
advantage. Their size.

If conditions are right, many
animal species get larger

as they evolve over millions
of years. Take T. rex as an

example. This is a cast of
the lower jaw of a predecessor

called Gorgosaurus, which
lived 72 million years ago.

Whereas this is the cast of
the lower jaw of a T. rex, which

lived five million years
later. Look at the difference in

size. But the bigger the
creature, the more energy they

need to stay alive. So when
catastrophe strikes and food is

scarce, the largest tend to die
out, whilst the smallest often survive.

That's one of the reasons why
many of the smaller mammals

lived through the great
darkness. And they weren't alone.

Robert's fossil turtle may have been
unlucky, but many others survived.

As did crocodiles, snakes, and
many fish species. And as for

the dinosaurs, did the
impact really kill them all? Well,

this beautiful fossilised
feather isn't from a bird, but

from a predatory dinosaur. So
we have to be careful when we

say that dinosaurs are extinct,
because what we call birds

originally evolved from the
smallest feathered dinosaurs. So

to be correct, we should say all
non-avian dinosaurs are extinct.

Robert's finds have given us
a better idea than ever before

about what happened on the
day that led to the extinction of

the largest beasts
ever to walk the Earth.

Dinosaurs were perhaps some
of nature's most extraordinary

creatures, dominating the
planet for over 150 million years

before they became extinct.

But extinction comes in
different forms, and many of

the amazing creatures and
plants alive today are also

threatened. It's possible that
humanity is having as big an

impact on the world as the
asteroid that ended the age of

the dinosaurs. As human
beings, we are unique in our ability

to learn from the distant past.
Now we must use that ability

wisely, and do our very
best to protect the millions

of species for whom,
alongside us, this planet is home.

NASA Jet Propulsion Laboratory,
California Institute of Technology