Attenborough and the Giant Dinosaur (2016) - full transcript

I'm here in Patagonia in the southern
part of South America because,

a few years ago, a man looking
for one of his lost sheep found

a simply gigantic bone
sticking out of a rock -

a bone that was going
to astonish science.

That first bone led to the
discovery of over 200 others.

They were all huge - so big that they
could only have come from a dinosaur.

And what a dinosaur it
would turn out to be!

One that seems to defy
the laws of nature.

These bones are part of a
skeleton that has remained hidden

and marvellously preserved
for 100 million years.

An international team of
scientists assembled to try



and work out what sort of
dinosaur it belonged to.

It's like a palaeontological
crime scene!

Each bone is an important piece
of evidence that can give us

information as to what the living
creature was actually like.

We'll use the latest
forensic technology,

we'll compare it with how
giant animals live today

and we'll build a full-size skeleton
of this stupendous creature.

And we will try and work out in detail
what it looked like when it was alive.

Absolutely amazing!

Could it really have been the biggest
animal ever to walk the earth?

ATTENBOROUGH AND THE GIANT DINOSAUR

Patagonia in southern Argentina.

Like many detective stories,
this one began by chance.

A shepherd stumbled across the tip of
a huge bone poking out of the ground.



Experts from Patagonia's
premier palaeontological museum

confirmed it was part of a dinosaur.

But they didn't realise at the time what a
truly extraordinary one it would prove to be.

Dinosaurs of many kinds roamed all over these
lands in the southern end of South America

during what's known as
the Cretaceous period,

between 66 and 145 million years ago.

The largest were plant-eaters
known as sauropods.

And the largest of them
were the titanosaurs.

Giant titanosaur bones
are comparatively rare

so very little is known
about these dinosaurs.

This new discovery
could change all that.

Like many people, young and old,
I'm fascinated by dinosaurs,

so the chance to join this investigation
is just too good an opportunity to miss.

Oh, I'd love to have a go!
- I'm sure they'd let you.

Of course, it's the giants in particular
that capture the imagination.

The first sauropods to appear on earth
were comparatively small creatures.

This is the cast of the
thigh bone of one of them.

It's not even as big as my thigh bone.

But after about 20 million years,
some had become pretty big.

This is a thigh bone from
one of those creatures.

But then, after that...

our giant appeared.
This is its thigh bone.

It's the largest ever found.

Coming across such a bone in your
back yard must be quite a shock.

Just ask farm owner Alba Maio.

I don't have many sheep
but I do have dinosaur

We're surprised and shocked.

Apparently it's a unique
specimen of its size.

Before long, a whole team of fossil-hunting
scientists arrives and starts work.

The thighbone proves to be eight feet,
2,4 metres long.

It's preserved in extraordinary detail,
and detail will be

critical to the forensic
examination that will follow.

The research team soon turn
the site into a vast quarry.

It proves to be one of the biggest
dinosaur finds of the century.

Bone after bone emerge from the rocks.

We just found another bone right here.
We weren't expecting it at all.

We just start digging and find it.

Until recently, giant titanosaurs have
only been known from a dozen bones

and our team have already found
more than ten times as many.

Dr Diego Pol is the chief palaeontologist
leading the investigation.

If you really want to know what a really
gigantic dinosaur looked like, this quarry here

has the potential to answer that question
and that's really exciting for us.

It's really impressive. When you stand by
one of these bones, you really feel tiny.

With so much new evidence,
there is a chance of discovering

all kinds of new facts about
the mysterious titanosaurs.

It's like a palaeontological
crime scene.

It's a really unique thing that you will
not find anywhere else in the world.

Patagonia's harsh weather makes
uncovering the fossils exhausting,

but it also endangers the
newly-exposed fossils.

A lot of damage from the rain so we need
to protect the bones that are at risk.

I'm really concerned that
this already has some cracks.

If the bones aren't protected, tiny
details on their surface could be lost.

To protect the bones,
they're covered with, of all things,

wet toilet paper and plaster of Paris.

It's like putting a plaster
cast on a broken leg.

There's a rush to get them back to the museum
to begin examining them in minute detail.

A new road has been specially
built to enable them

to be transported
without too much jolting.

Once at the museum laboratory,
the detailed detective work begins.

It's a chance to start
putting flesh on bones.

Some really big muscle
was going in here.

This animal was so big
that it certainly needed

really powerful muscles and very
strong attachments into the bones.

This is a giant vertebra, one of the bones
of the spine, and it's a very important find.

That's because it's likely
to provide crucial evidence

for identifying the
species of our dinosaur.

Despite weighing up to half a tonne,
these fossils are surprisingly fragile.

It's all rather nerve-racking.

One bone like this has already
cracked in half without warning.

And so this is the
position as it was in life

with the centre of the backbone there,
then this is the crest on the top.

Right, right, and this belongs
to the middle part of the thorax.

Right about here.
- About that. - Yeah, yeah.

Many more weeks of detailed examination

will be needed before the backbones
reveal all their secrets.

Surprisingly, perhaps,
one of the first things

the team was able to deduce about
our titanosaur is its weight.

That's because,
after finding the thigh bone,

they discover another huge bone
from the front leg - a humerus.

By measuring the circumference
of each of these leg bones,

it's possible to estimate how
much weight they could support.

Let's see how much.
We'll measure this.

79.
- 79?

I'm not sure how that
translates to body weight.

Yeah, around 70 tonnes or even more,
probably.

That's really big.
- It's amazing.

That evening, Dr Jose Luis
Carballido checks his calculations.

I've been calculating how
heavy the dinosaur was.

It weighted more than Argentinosaurus!

Until now, Argentinosaurus was
the heaviest known dinosaur.

Ours already looks bigger.

Could this mean it was the largest
animal ever to walk the earth?

Could it also be a new species?

We can't be sure... yet.

The rocks of Patagonia,
so bare of vegetation,

also contain astonishing evidence of
how titanosaurs began their lives.

I've now come nearly 500 miles north

from our Patagonian dinosaur excavation
to a place called Auca Mahuevo.

This is the largest dinosaur
nesting ground yet discovered.

The remains of their eggs and
their nests are wherever I look.

In fact, it's quite difficult for me

to take a step without walking
on a dinosaur eggshell.

Over thousands of years, the wind and
the rain have cleared away the soft rock

that once enclosed these fragments

and they can tell us quite a lot
about how titanosaurs reproduced.

Careful excavation has
shown that these dinosaurs

laid eggs in clutches of
up to 30 or 40 at a time.

They would have looked
rather like these replicas

because they lay on the
surface of the ground,

not covered by soil,
but in a shallow depression.

Sometimes, though, remains of vegetation
have been found in some nests,

which suggests that the dinosaurs might have
used rotting leaves to help with the incubation.

The dinosaur that laid these
eggs here were medium-sized.

Our dinosaur that we're excavating,
probably laid eggs as big as that.

I'm shown around by Dr Luis Chiappe who, with
his team, discovered this remarkable site.

Dinosaur eggs here were
laid on an old river plain.

Then the river flooded and covered the
unhatched eggs, preserving them in mud.

You see, you know, many eggs...
- There.

for kilometres and kilometres.
Here's a nice one.

Oh, that's a huge piece!
- Yup.

And this is the actual surface of the egg?
- Yes.- Astounding.

Do you suppose they could have
been coloured like birds' eggs?

They may. Maybe they were off-white.
We can't tell really. - Yeah.

Well, we can see all the
tiny pores on the surface.

And the texture.
- Yeah. What a beautiful piece.

You must admit it's pretty romantic.

I think it's incredible.
- I think it's absolutely extraordinary

and I must put it back where I found it.
- Thank you.

The fragments could tell us quite a
lot about how the dinosaurs nested.

But some, amazingly,
can do even more than that.

All these examples have
something quite special.

This one is my favourite.
And what you can see

is a very large patch
of baby dinosaur skin.

How wonderful! It's extraordinary.

And this is not just an impression,
this is the mineralised skin. - It is.

Yeah. Astounding.

The eggs were not just
preserving the bones,

they were also preserving
the skin of these babies. - Yeah.

This was just on the surface. I remember
picking this up and brushing it a little bit

and then using my hand lens and
looking at this exact patch of skin

and I realised that
we had found something

that no person had ever seen before.

You are the first human being
ever to see a baby dinosaur's skin. - Yes.

It was just an amazing...
amazing moment.

It must have been very
close to hatching.

It's almost complete, this thing.
- Yes, that's what we believe.

And then a flood...
- Killed them all.

Unfortunately for them, good for us.
- Yes.

Luis Chiappe has dozens of
complete eggs in his museum and

he allows me to examine some of his
most precious specimens for myself.

There are many other remarkable things
in these astonishing time capsules.

This one has got,
perfectly clearly, the limb bones.

Here is a skull.
That's the orbit of the eye,

there's the lower jaw,
there's the snout.

This one also has a skull,

but on the tip of the snout you can
see a little spike which is like the

egg tooth that a bird embryo has to
help it crack itself out of a shell.

And here is a replica
of what the complete,

un-crushed shell must have looked like.

With all these details, it is possible to
imagine how a baby titanosaur entered the world.

To get an idea of how these
youngsters might have lived,

we can compare them with their
closest living relatives - birds.

Rather like baby ostriches,
a young titanosaur

would have been able to
walk soon after hatching.

They may well have gathered
into groups to give some safety

from predators, as young ostriches do.

Microscopic analysis of dinosaur leg
bones show rings, rather like tree rings,

and these indicate that titanosaurs
grew very swiftly early in their lives

and they could have lived for some 50
years, plenty of time to become enormous.

The team now has 150
bones of our titanosaur,

enough to get an idea, not only of its
weight, but also its height and length.

Now, the plan is to build a life-size
reproduction of the complete skeleton.

It's a challenge to find a place
big enough to house an animal that's

four times longer than a London
bus and nearly twice its height.

But Diego thinks he's found one.
It's an old wool warehouse.

One, two, three, four,
five, six, seven...

We have been looking for a place that
is big enough to fit our dinosaur.

This seems to be it.
This is a warehouse that we could use,

not only in terms of the length,
this is 70 metres long,

but also it's very important
in terms of the height.

So we need a place not only long,
but really high.

It really needs a little bit of
decoration, but I think it will do it.

It's going to be awesome!

Putting the skeleton
together will help us

understand the particular
challenges of being such a giant.

So, next, an international team
of skeleton builders arrive

to scan the bones ready to make a
3-D computer model of each of them.

3-D scanning,
accurate to 0.01 of a millimetre,

allows images of the bones to be
placed in a virtual reality world

so that they can now be
examined from all points of view

without needing eight
people to lift them.

One of the mysteries
surrounding our dinosaur is,

how could an animal as big as
it was actually move about?

The computer data allows us to put
our dinosaur leg bones together in 3-D

and then compare the arrangement with
what we know about living animals.

Elephants are the largest
land animal alive today.

They, like titanosaurs,
have to move their massive bodies around

without their bones shattering
under the enormous weight.

I've come to meet Professor John
Hutchinson here at ZSL Whipsnade Zoo.

He's studied elephants for many
years and has joined the team

that's investigating the internal
workings of our titanosaur.

We have about a one-metre long
pressure sensitive mat out there

with several thousand sensors in
it and it's telling us, in very

high resolution, what the pressure
on an elephant's foot is like.

We can see on the
elephant's foot here...

Here she goes... - Yeah! Great.
- That was a perfect one! - Bull's-eye!

The pressure hits the ground, rolls over
and then pushes off with its toenails.

So we can see there some hot colours,
or reds and oranges,

on the toenails of Melvin's
foot indicating high pressure.

And then some cooler colours back towards
the heel pad in the greens and light blue.

That's low pressure. So elephants are supporting
most of their weight on their toenails.

That pressure gets transmitted
up to their toe bones

and then up to their wrists
and ankles and so forth.

John's analysis suggests that our
titanosaur's legs, like those of an elephant,

were placed vertically beneath the
body like strong, massive columns.

This arrangement transmits
the weight to the toes

and then spreads the force, using fatty
pads in the back feet, as shock absorbers.

But our titanosaur had one other adaptation
to help them walk - one that elephants lack.

A clue to this can be seen
on the giant thighbone.

How's it going?
- Good, good.

Ben Garrod specialises in
reconstructing skeletons

and he's joining the team to
look at the bones in detail.

Marks on them show clearly
where the muscles were attached.

That's halfway down the femur,
isn't it, that big lump there... - Yes.

for these massive muscle and,
I guess, tendon attachments?

This lump is where a huge muscle
was attached to the femur.

The other end of this muscle was
connected to bones like these in the tail.

It's this connection that
helped our dinosaur to walk.

They've got so much strength
and so much rigidity up there.

They actually used their tails to
help move, to help their propulsion.

So they had massive muscles and tendons from...
- Help...?

Yes, so the movement of the tail
actually pulled the hind legs

backwards and then raised them forwards.
- I see.

I must try that sometime!

The largest lizard alive today, the
Komodo dragon, has a similar adaptation.

The swing of their tail helps their
back legs move more efficiently.

Of course, our dinosaur was different,

not least because it
weighed over 500 times more.

And that makes John Hutchinson
suspect that it would have

had to deal with another problem -

one also faced by passengers
on long-haul flights.

Pressure in the legs of big
animals is a really big problem.

If blood stays down there too long,
it's going to pool and clot.

Much like airline socks that humans use,
large animals,

again and again,
have evolved very thick elastic skin

around their lower limb that helps
to keep that pressure very high.

Actually, I can empathise. I have to wear
those same kind of stockings to get my blood

back up my long legs!

Time to thank our helpful elephant.
You're a lovely thing. Yes, you...

Oh, you want one! OK, in you go.
Thanks. Thanks, pal.

That's all I've got!

A giant animal like an elephant also needs
a huge heart to pump blood around its body.

And so did our titanosaur.

Its heart must have been immense.

From our new, detailed knowledge
of the skeleton, John Hutchinson

has calculated that it was more
than six feet in circumference.

It probably weighed 230 kilos

and would have had to shift 90
litres of blood with a single beat.

There's one!

And it would have had to repeat
that beat every five seconds.

There it goes again.

Weighing more than three grown men,

it would have been
extraordinarily powerful.

And in order to pump blood
around the body at high pressure

and then into the delicate
lungs at a lower pressure,

it's thought that our titanosaur's
heart had four chambers -

more like that of a bird than a reptile.

So, a powerful heart pumped the
blood to the extremities of the body,

but how did the blood get back?

As in an elephant,
a combination of fatty footpads

and tight skin are thought to have
forced the blood from its legs...

all the way back to its heart.

Toronto, Canada, and the world's
biggest dinosaur-making factory.

The team is building a life-size
skeleton of this vast creature

to be unveiled in Diego's warehouse
in Argentina in six months' time.

First, they have to turn all the information
from the 3-D scans into each individual bone.

State-of-the-art robots
carve moulds from polystyrene

so that the bones can
be cast in fibreglass.

Up until now, the fossil bones
have been the main focus of the dig

but the rock that surrounds the fossils
also holds important information.

The nature of the layers of rock in
which these fossils lie can tell us

a great deal about how they got to be
where they are and how old they are.

Some of these layers are
volcanic ash which must have come

from a volcano erupting every now and
then somewhere in the neighbourhood.

And this ash around the bones can
tell us how old the fossils are.

Scientists worked out
that all these fossils

dated from the Cretaceous
period but better than that,

they dated them precisely
to 101,6 million years old.

By a detailed forensic examination
and comparisons with living creatures,

the team have deduced a great deal
about the life of our titanosaur.

We now know when it lived,
how big it was,

how it moved and what its
young might have looked like.

We've even calculated its heart rate.

In an investigation of this scale,
sometimes the most important

information comes not from the most eye-catching
evidence but from quite tiny details.

Here is something that I really hoped
the excavation was going to find.

It's a tooth.

And it's tiny compared with the size
of the huge animals from which it came.

Teeth can tell you a huge
amount about an animal.

And if you look at the tip,
you can see that it has been

worn into two facets on either side.

And that tells us that this tooth
engaged with the teeth on the other

side in an alternate way like that,
not head-on but one on either side.

So this animal, like a pair of scissors,

just nipped off the vegetation
on which it was feeding.

Enormous though it was, just nipped
off little leaves and here are fossils

of some of the different kinds of
plants on which it might have fed...

cycads, ferns and conifers.

One thing these plants have in common

is that they're all very
fibrous and hard to digest.

To get enough nutrients
from such poor quality foods

our titanosaur would have had
to eat them in vast quantities.

A descendent of one of these plants
still grows in Patagonia today.

200 million years ago when
South America, Australia

and Antarctica were all joined together
to form a supercontinent called Gondwana,

a particular kind of vegetation
was dominant - they were conifers.

They continued to survive
to 100 million years ago

when our titanosaurs were
roaming the land and a few still

survive today. Here in the foothills
of the Andes is one of them.

The monkey puzzle tree called araucaria.

Trees, like araucaria, show that the
dinosaurs must have had another problem.

These conifers, apart from being poor-quality
fodder, can grow to over 130 feet in height.

They would have been out of reach for
many animals but not our titanosaur.

Here, boys, come on.

It's pretty clear why a long neck
is useful for a land-living animal.

It enables it to reach vegetation
which is growing high up

at the top trees that other
ground-based animals couldn't reach

and it must have been much
the same for titanosaur,

except we know from the fossils that
titanosaur's neck was very, very much longer.

And that enabled it to sweep
its head in a great wide arc

and even to reach between two
tree trunks that happened to be

growing close together
to get other vegetation.

What about that?

This enormous reach would have saved
our titanosaur a lot of energy.

It only needed to move its neck to feed,
not its whole body.

But how did it eat enough of this
poor-quality food to survive?

Elephants face a
similar challenge today.

An elephant can collect
and chew about 130 kilos -

that's 300 pounds of
vegetation in a day.

But our titanosaur could have
eaten five times that amount.

It's been estimated that a large
titanosaur would eat enough

plant material to fill
a skip in a single day.

So how did they digest it all?

Elephants solved the
problem by giving their food

long preparatory chews but
titanosaurs didn't bother.

They simply gathered leaves by nipping
them off and then swallowing them whole.

But that in turn would mean
that they needed a bigger

and longer gut to digest
all that unchewed food.

And it might well have taken ten days
for food to pass through their system.

A bigger gut needs a bigger body so
titanosaurs grew bigger and bigger

until they approached the limits
of what their bones could support.

Two years after the dig began,
a strange cargo arrives,

having made a 7,000 mile
journey from Canada.

Dozens of packing cases later and all the
bones are finally in Diego's warehouse.

Assembling the skeleton
can finally begin.

The 3-D data used to make the skeleton has
also been used to create a computer model.

It means I can get a preview of what
the final skeleton will look like.

The first thing is these very,
very lovely legs.

If we turn it around, they are very, very
column-like and this is like elephants

but interestingly this titanosaur
had slightly splayed legs,

at an angle of about five degrees
and this slight change would have

really increased the ability
to take all that extra weight.

You see the splay because of the joint or
because of the shape of the bone? - Both.

You can tell from the shape of
the bone and from where certain

parts of the bones form and how
they sit and then how the bones fit

with one another you can really tell
how it would have sat in real life.

Another thing you can see is a very,
very long neck.

And we just found out that
ours had 15 bones in its neck.

Interestingly, some of them were five
or six times longer than they were wide.

These incredibly long vertebrae and there's lots
of them. - Why does it have such a long tail?

Well, a couple of reasons.
If you've got an animal this big with

a neck this long, the last thing
you want to be is top-heavy.

And CAN research has just shown
that the centre of gravity

in this animal was somewhere right
in the middle of the chest cavity.

So the heavy tail counterbalances
the exceedingly long neck.

But judging from the size of the muscle
attachments, the tail was also immensely strong.

It had huge muscles from around
here right down to about a third

of the way down the tail,
somewhere around here.

So that would be solid flesh?
- Yep, muscle tissue, other tissue,

ligaments, tendons.
- Do you think they might have fought with it?

Possibly. - Thrashing it about?
- It could've been used as a defence mechanism

so you're walking up to that as
a predator, the last thing you

want to be is on the receiving end.
- Don't put me into it!

Yeah.

The long and painstaking examination
of the backbone has now borne fruit

and Ben has got some important news.

This is a vertebrae here from right high up
in the back, right near the shoulder blades.

And the most important thing is
this little ridge that ends in this

big lump and this is only found
in this particular dinosaur

so from that and a few
other physical differences,

we think we have got a brand-new,
exciting species.

So our titanosaur is not only a giant,
it is indeed a new species of dinosaur.

Examining the spinal bones also reveal something
about how it coped with life as a giant.

This is where the spinal
cord would have passed.

So this hole straight through here?
- Mm-hm.

The whole nerve centre,
as it were, - Yep

the cable carrying all the nerves.
- From the base of the tail

right to the skull. - It's very small.
- It is, yeah. - Ours is what?

About thumb width.
- So it's not all that much bigger. - No.

This cord was well over 100 feet long.

It would have taken about a second for a nerve
impulse to go from its tail to its brain.

And what's more,
the spine has revealed another surprise.

It is full of holes,
rather like a Swiss cheese.

The neck bones of titanosaurs
contain so many holes

and spaces that they
weighed around 35% less than

they would have done had
they been made of solid bone.

The leg bones of modern
birds are much the same.

And those spaces serve another
very important function.

They contained air sacs.

These air sacs were
connected with the lungs.

So what was their function
and how did they work?

They occupied much of the chest
and ran along the whole length

of the body along the backbone

to the 17-metre-long neck
and then to the head.

It's thought the balloon-like sacs
had thin but strong membranes.

These sacs acted like bellows,
forcing air into the lungs.

When we breathe in,
air flows down into our lungs,

oxygen is absorbed in exchange
for carbon dioxide which is then

got rid of when we breathe out.

The air sac system is very much more
complex but very much more efficient.

It enabled a titanosaur to
take in oxygen continuously,

not just when breathing in
but also when breathing out.

Our titanosaur wasn't the
only giant living around here.

This was a dangerous world,
where meat-eaters were giants too.

New evidence from the dig site shows that
carnivorous dinosaurs were here as well.

So these are some of the over 80
teeth we found on the dig site.

And you can feel how sharp they are.

Yes, it's serrated, just like a shark's tooth,
in fact. - Absolutely.

They actually belong to a family
known as a shark-toothed dinosaurs.

We can identify the teeth
at the family level.

We know of one species that
belonged to that family,

it's called Tyrannotitan chubutensis.
- Tyrannotitan? - Yeah.

That means a ferocious giant, ferocious beast.
- Exactly. - Good name.

Yeah. - Chubutensis is because
of the area it comes from?

Yes, this is the Chubut province.
- Great.

Tyrannotitan must have been
a ferocious-looking beast.

With large eyes, sharp,
flesh-eating teeth...

and strong legs, it was a fast,
alert, meat-eating dinosaur.

And it was as big as T Rex.
- Really? Not as famous.

Not as famous.
- Tell that to Hollywood.

I have some bones over there
I would like to show you.

So this is one of the tail
vertebrae we found at the dig site.

There's something really interesting
here. You can see this groove?

Well,
this groove was probably a bite mark

made by one of the carnivores.
- By one of these teeth?

Right.
- So it was... What do you mean? Like that?

Exactly. Taking the flesh out of their tail.
- Really? - Yeah.

The tender bits.

They would be too.
- Yeah, absolutely.

Can you determine whether it was
a scavenger or it was a hunter?

We don't know if they were dead,
I mean, they were scavenging

on the carcasses, or if they were
actually hunting and killing them.

Well, it didn't make much
difference to the old dinosaur. - Yes.

In a detective story, to close the case,

you really want to know
how the victim met its end.

If our titanosaur didn't perish in the
jaws of a Tyrannotitan, how did it die?

Clues can be found by the
detailed three-dimensional mapping

of the location of every fossil bone,
small and large.

That shows that the dig site
contains the remains of not just one

but seven different individuals.
All of the new species.

And the first thing to notice is that
they are on three different levels.

That's to say the animals must have come
here on at least three different occasions.

But why should they have done that?

There are several theories
as to why seven bodies

should have all ended up at
this one particular place.

The first is that this was a seasonal
climate and that as the dry season proceeded

this was one of the last
remaining pools of water

and when this went, the sauropods
that happened to be here died here.

The second is that these bodies
were swept down by great rivers

during the rainy season and then where the
land levelled out, so those bodies were dumped.

Analysis of the sediments around the
bones shows that there were rivers

gently flowing across this site
at the time of their death.

There was no shortage of water to drink.

What's more the rivers were not moving
fast enough to shift such huge bodies.

So the corpses weren't washed
here by floodwaters either.

Could there be another reason why they all
died in one place on three different occasions?

We know from layers of ash
around the bones that there were

volcanoes erupting in the neighbourhood

so doubtless there were
areas where the ground was

warmed by volcanic fumes,
just as they are here today.

We also know that dinosaurs regularly
laid their eggs in such places,

doubtless taking advantage of the volcanic
warmth to help incubate their eggs.

So maybe that was the reason why they
kept returning to the same place.

Certainly the excavation of the
dinosaur egg site seems to support this.

Nests like these have been found at four
quite widely separated layers in the rocks,

showing that dinosaurs came back
to this particular site again

and again and again over
a long period of time.

Ash from a volcanic eruption can
sometimes fall in such quantities

that the whole vegetation is
blanketed by it and killed.

So life in the aftermath of a big eruption
can be very difficult for a plant-eater.

Whatever the explanation, individuals
over several generations came

to this one place and died here.

The dig is coming to an end and the team have
assembled a record-breaking number of bones

but they're still hoping to find one
last piece of the puzzle - the skull.

So what number's this, 203?
- Actually this is 223. - 23?

Between the seven individuals?
- Yeah.

Between all the seven
individuals we found here on this site.

If these are neck vertebrae,
could they be leading towards a skull?

Yes, that's what were hoping for. We just
found another neck vertebrae over there.

That would be a great triumph if
you found a skull, wouldn't it?

There are only three titanosaur
skulls known so far. - Really? - Yeah.

So they're very rare.
- And that's because they're very fragile.

They're very delicate bones
and they have

very light sutures
between each of the bones.

OK, well, let's hope you find number four.
- Yeah. - Could be under there.

Could be. We're going for that.
- Wonderful.

Alas, it was not to be.

So I gather you haven't yet found the skull.
- Sadly not.

The only thing we have found
out of the skull is his tooth.

So to complete the skeleton,
the team have to reconstruct one...

Take that piece out of there. - Basing it
on the three skulls of other titanosaur species

to produce one which most suits
the single tooth that we have.

The scientific team has discovered,
collected, cleaned,

scanned and copied 220
bones of our giant.

Soon it'll be possible to put those
copies together to get some idea

of what the living animal
actually looked like.

But the fossil bones themselves
still have many secrets

that are waiting to be revealed.

All the theory can now
be put to the test.

We can finally get the most accurate estimate
of our dinosaur's weight and true size.

It takes two weeks, working day and
night, to fit all the bones together.

God!

Absolutely amazing!

Good gracious!

Well, Diego, are you pleased with it?
- Yes, we are very pleased.

It is been a lot of work, it has
taken 40,000 man-hours to get here

but we're really, really happy with it.

And does it answer some of your
questions about the animal?

Yeah, absolutely.
It answers a lot of questions

but the good thing is it
raises more questions.

So we have a lot of research
to continue on this animal.

It's clear that this thing
still wasn't fully grown.

It's massive, but it still had room to go.
- You mean the structure of the bones looks as

though they were still growing?
- Yeah.

That raises the really big question,
is it the biggest so far discovered?

Well, according to our estimate,
this animal weighed 70 metric tonnes.

70 metric tonnes.
What would that compare with?

That is like 15 African elephants.
- 15 African elephants?

We are now sure that this animal
was 10% larger than Argentinosaurus.

The previous record-holder?
- The previous record-holder. So, yes,

we think we have the largest
dinosaur ever known. - Fantastic!

I can quite believe it.

Congratulations to you.
- Thank you. - Congratulations to he, she or it.

Wonderful!
A marvellous, marvellous thing!

Piecing this complex jigsaw puzzle
together has been a fascinating adventure.

It all started with the discovery
of one enormous thighbone.

And then a team of 40 worked
for over two years to excavate

and put together the near-complete skeleton
of the largest land animal yet discovered.

And so added one further marvel

to the astonishing
history of life on earth.

What a thrill it must have been
to see it when it was alive.