Original subtitles

DAVID ATTENBOROUGH: I'm on the south coast of England

in what is known as the Jurassic Coast.

150 million years ago,

the land was ruled by dinosaurs...

...but the oceans were dominated

by a mysterious sea monster, known as a pliosaur.

Its remains are very rare,

but some have just been discovered

in the cliffs behind me.

This could be one of the largest, best preserved pliosaur skulls,

ever found.

And now, working with scientists,

we can uncover more about this prehistoric giant, than ever before.

What an extraordinary, terrifying thing!

Could this be the greatest Jurassic predator

that ever lived?

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Britain has a wealth

of fossil sites,

but perhaps none are quite so famous as this,

the Jurassic Coast.

I've been collecting fossils since I was a boy,

and I haven't yet got tired of it.

These days, you're supposed to wear glasses for safety.

And, if you would know a locality,

you would begin to recognise the sort of block

that might contain a fossil.

And this rock was split earlier

to make it easier to show you.

And if I can...

..hit it quite hard about there...

HE LAUGHS

What about that?

Is anything more beautiful than that?

Fantastic.

Finding even the smallest fossil

is a thrill, but discovering something much larger

can be an unforgettable moment.

And that is exactly what happened

to a fossil enthusiast,

who was walking along a beach

near Kimmeridge Bay in Dorset one morning.

I just found something quite extraordinary -

it's the jaw of a massive pliosaur.

It's enormous.

It's a massive pliosaur.

It's the best fossil I've ever found.

It must have just come out of the cliff up there somewhere.

Renowned fossil expert Steve Etches was called in,

and he realised immediately

that this find could be hugely significant.

Look! Look at those teeth.

There's a tooth there - look.

Let's have a look at the front.

You can walk along here for hundreds of times

and not find anything,

and then, occasionally, you'll hit the jackpot.

And this certainly is the jackpot.

It's the snout of an enormous pliosaur skull.

And Steve suspects that the rest of the head

might still be embedded in the cliff above.

But he needs to work fast

before the whole thing tumbles into the sea

and is lost for ever.

So he quickly gathers a team of experts,

including fellow fossil-hunter Chris Moore.

It's day one of the dig.

Steve and a team of diggers are up on the cliffs.

They're putting a net down to stop any loose rock

rolling down and hitting us,

and then we'll go down and expose the skull.

DRILL WHIRS

Steve and Chris have worked together for decades.

But this is the biggest challenge

they have ever faced.

The skull is over 12 metres up, from the base of the cliff,

lying upside down in a horizontal position.

It's full length is not yet known,

but Steve believes it could be over 2 metres long.

But how did the fossil end up here?

Well, these rocks were once mud on the seafloor...

..in which the remains of prehistoric marine creatures

were buried.

Over millions of years, the continents shifted,

the seas receded,

and today, as these cliffs erode,

fossilised skeletons are revealed.

The jaw is there, and the idea

is to actually cut this down vertically,

and then we form a platform where the fossil is.

I've known Chris and Steve for many years,

and I can't wait to join them

and find out how they're getting on.

Here, we've got a live feed to them actually digging

halfway up the cliff face.

What's happened so far,

the tip of the snout has already come out and been recovered,

so the rest of it is going into the cliff.

What exactly are they doing there?

At the moment, they're using tinfoil

to try and protect the exposed piece of jaw.

In case something falls on it and breaks it?

Yeah. Yeah, yeah.

And then they're also using superglue to consolidate

the crumbly teeth and parts

that have been weathered over millennia.

And they're hanging by ropes there?

Yes, pretty much in the centre of the cliff.

Dear me! Pretty dangerous stuff, this.

Yeah, yeah, it really is.

After you've worked there for a few hours,

it becomes a bit more natural.

And you concentrate on the actual digging.

You must be pretty sure that there's something there

to put this amount of effort into it, really.

Oh, positive there's something there.

It's beautiful.

It's a beautiful specimen.

Is it? Yeah. Amazing.

But what can this spectacular find reveal

about the lives of these mysterious sea creatures

and the world they inhabited?

In the Late Jurassic,

Europe was an archipelago of islands

much closer to the equator than it is today.

Its seas were warm, shallow and teeming with life,

and, in these waters, underneath my feet,

lurked the ultimate marine predator...the pliosaur.

Unlike dinosaurs that lived on land,

these colossal marine reptiles

spent their whole lives in the ocean.

They're thought to have been around 10m in length...

..that's about the size of a double-decker bus.

They had long, broad flippers,

short, strong necks...

..huge heads

and enormous jaws.

But there's still a lot we don't know

about these great sea monsters,

which is why this new discovery

is so important.

Steve believes that the entire pliosaur

may still be inside the cliff...

..but it's the skull on which he's concentrating.

A skull can reveal more about an animal

than any other part of its skeleton.

Finding a complete specimen is rare,

but it can tell us a great deal

about how the animal lived.

It's quite hot and thirsty work.

Steve and Chris think they will have

about three weeks to dig the fossil out

before the storms of late summer come.

This is a learning curve.

I thought, stupidly,

that it wouldn't be quite as hard as this.

We're probably over a metre in.

There's the skull there, just behind me.

It's up to us now to get it out without any damage.

If the skull is successfully extracted,

it will be taken to the Etches Collection Museum

in Kimmeridge, which was founded by Steve in 2016

and now contains nearly 3,000 fossils

from the Jurassic period.

This was where the pliosaur snout

was brought to be assessed.

And I've come here

to learn what Steve has found out so far.

What an extraordinary and terrifying thing!

Huge teeth. They are. They're massive.

These big, fang-like teeth that come up.

And they interlock. Yes, they do.

So how far do these teeth extend?

They come right up here.

Is that characteristic of this?

Yes, typical pliosaur.

It's trihedral teeth, they're sort of...

They've got two sharp cutting edges

and then a flat face on the inside.

They must have used that to rip apart ichthyosaurs.

Ichthyosaurs, plesiosaurs as well -

we've got evidence in the museum.

Because they've got subtriangular teeth,

when they bite into a bone,

they leave a very distinctive tooth hole.

Well, that's pretty unusual to find teeth in position. It is.

This is the first pliosaur I've ever seen

with actually closed jaws.

It is extraordinary. Mm.

It is quite extraordinary.

And there is another unusual feature

on this snout.

So let me show you the other side. I'll spin it round.

Oh, gosh. There's a lot of stuff here.

Oh, yeah. And these...

These holes here.

Well, I think these are sensory pits,

they're all on the snout.

If you look at them, they go...

See, they strike back in at an angle. Yes.

They're sensory pits for picking up its prey,

I'm pretty sure. Pretty impressive beast.

Astonishing. Mm.

But exactly how did these sensory pits help our pliosaur to hunt?

These days, we have equipment

that can help us answer such a question.

We take the snout to the University of Southampton,

which has some of the most powerful

CT scanners in the UK.

Once the snout has been scanned,

paleobiologist Dr Neil Gostling

is looking for clues about the sensory abilities

of our pliosaur.

So what does this scan tell us?

I've taken the CT data,

and we can rack our way through this stack of images

and we can see all of those internal structures,

which otherwise wouldn't have been revealed to us.

And there were some things which are, I think, quite exciting.

We've got these little structures in red.

And I had to do these, each one, slice by slice,

dot by dot, because there's lots of imperfections and holes in it.

But these are continuous,

and I think these are blood vessels,

little branching blood vessels.

Now, come on. BOTH CHUCKLE

You're really telling me

this block of stone can show blood vessels?

Yes, and what I think we've got here

are actually branches of the trigeminal nerve.

And these are the sensory nerves

in your face that allow you to feel

fingers dancing over your cheeks and what have you.

But if you're in water and you've got these sensory pits,

you can detect changes in pressure.

That's going to give you an advantage

in what might be murky water,

where your eyes aren't working so well.

So you can always be sure

that you're going to catch your next meal.

Fantastic.

Knowing how these senses worked,

we can start to build up a picture

of how our pliosaur hunted.

Its prey...

..ichthyosaurs -

reptiles much the same shape as a modern dolphin

and similarly fast and agile.

The sensory pits found on our pliosaur's snout...

...may have acted like miniature pressure pads,

detecting the turbulence produced by ichthyosaurs

as they swam through deep water.

In effect, our pliosaur was able to stalk its prey

even in the darkest depths, just by using its skin.

There are animals today

that have similar sensory systems.

Crocodiles have over 9,000 pressure receptors,

which are concentrated on their snouts,

each one of which is thought to be ten times more sensitive

than a human fingertip.

Two weeks into the dig,

and the work is proving to be even harder

than anyone was expecting.

Let me throw this big chunk away.

But, at last,

there's a breakthrough.

There's something under there which is huge.

Here, you've got the jaw showing,

and this one's heading back this way.

It's going to be the underneath of the skull.

There's a vertebra there.

There's another vertebra there.

Finding these bones confirms that the entire skull

really is inside the cliff.

It's nice to actually see something.

You feel like you've been rewarded a bit.

What Alex is doing, he is chipping out a loose tooth.

Hang on, that's the crown! Yeah. Oh, that's interesting.

Yeah. Keep going. LAUGHS GIDDILY

This is part of the root and there's a pulp cavity there.

That tooth will be probably about ten inches long.

THUNDER RUMBLES

Oh, the thunder's coming. Oh, look at that.

Just as the dig is revealing further exciting finds...

Go on, guys. Yeah, come on, Chris.

We've got a lot to do. We've got to get you all up.

..conditions become treacherous,

and the rope safety team decides

that it's too dangerous to continue.

Now it's rained, this lithified mudstone

is turned like a slippery clay, it's lethal.

There's certainly no way now, with us stopping now,

that we're going to get it done in those days left.

The weather may be against them,

but finding a pliosaur tooth is a real stroke of luck.

It could also help us understand more

about the type of prey our sea monster could eat.

The teeth of marine predators vary according to their function.

Some are used to shred and slice...

...others to grasp or crush.

So what do we know about the teeth of our pliosaur?

Back in Southampton... MACHINE WHIRS

..the investigation of the pliosaur snout, has revealed something even more intriguing

These teeth are extraordinarily well preserved, aren't they?

Is there new information that we can get from this?

Well, from the CT scan,

if we take it back again so we can expose the teeth,

these are large, pointed teeth,

and these are really well adapted

for grasping slippery fish.

But this is on an order of magnitude larger,

which would have allowed it to eat all sorts of prey

that are swimming around

in the ancient Kimmeridge Bay of the time.

Were the teeth permanent, or were they replaced?

As we move it back through,

we can see that we've got individual teeth

almost all the way along.

However, in one place,

we've got this little tooth here,

and this is a replacement tooth.

The thing that most animals die of

is that their teeth have worn out,

and they can't feed any more.

And, if you are a large predator

and you are catching large prey,

you might lose teeth relatively frequently.

Well, this isn't such an issue if you can replace your teeth

multiple times throughout your life.

Not only were its teeth replaceable,

but they were also shaped differently -

long and sharp towards the front of its jaws,

more hook-like at the back.

This deadly combination meant

that pliosaurs could feed

in a variety of ways,

from grabbing large sharks and squid

to gripping smaller, slippery fish.

METALLIC HAMMERING

Three weeks into the dig, the weather is holding.

And now the biggest question for Steve and Chris

is how to lift the skull off the cliff.

I reckon we take out a big slab.

One piece? Yeah.

Cut it underneath? What, cut underneath?

Yeah. All the way through?

Yeah. I can't see any other way of doing it.

If we do it any other way,

it's going to just crumble up.

What do you think? I think I'm going home and not coming back!

Luckily, for Steve and Chris,

friend and local farmer Rob Vearncombe

has been devising a solution.

He's building a crate, which will be lowered down the cliff,

into which the skull will be manoeuvred

and then hauled up to the top.

The theory is that whatever angle the skids are,

as it comes up the cliff,

the box stays level to protect the fossil

because we're trying to keep the fossil

as level as possible.

The big day finally arrives,

and a local army of helpers is assembled

for this crucial stage of the operation.

And Steve is feeling the pressure.

With the best will in the world,

it looks like it's all going to function,

but the risk is immense. You know, what happens

if it just actually turned on its side?

There's a lot of things that could go wrong,

so it's a risky sort of time.

This is one of the largest and best-preserved

pliosaur skulls ever found.

So the stakes are very high indeed.

When it comes down, we've got to get that aligned

and we've got to get that jaw, that skull inside that box.

And we've got to be really careful

that that sled has got a metal bar

and, as it comes down, it doesn't hit the nose.

No-one's ever done this before, ever.

Extracting a giant skull halfway down a cliff face!

After weeks of back-breaking work,

emotions are running high.

Down! Come on. Quick! Quicker!

This moment's really fraught.

We've got one skid just about glancing the side of the skull,

and we've got to try and pull it out now

to get it over the edge.

Very slowly. Six inches.

One clumsy move,

and the skull could be smashed.

Oh, my... Oh, pull! Pull again.

My hand... That's all right. Missed it! We've done it!

Stop, stop!

It's all pretty stressful.

Every part of this is really, really stressful.

After quite a few hours, we've got it into position.

We haven't knocked the end of the snout off so far,

and it's all ready to go.

But the next stage looks even more risky.

Just retreat from the edge,

and we're going up the ropes now!

Al and Steve are going to go up to the hole

and attach the winch,

and then start the process of slowly dragging it into the box.

Shifting a fossil that weighs over half a tonne...

HE GRUNTS ..is really dangerous.

It's moving. It's very nervous and it's very tense.

So let's see how it goes.

Oh... Go on.

That's good. That's better.

That's... Whoa!

Right, I think slide it straight in.

Steve, is it OK? Has it come off OK?

Well, we're losing a bit of it, but you can't help it, mate.

Go on. Go on.

Now it's on it. There you go.

Right. Off you go.

That's it. Good, that'll do.

That's well in.

RADIO: It's right in the cage now.

Hey, the fossil's in!

Brilliant, mate. We're all cheering here.

Well done. Well done.

Well done, everybody.

Right, well done. Brilliant.

We've overcome a lot of problems to get this far,

and we've done it by the skin of our teeth.

The skull, at last, is in the crate...

RADIO: Take up the slack again.

..but shifting it carelessly, let alone dropping it,

could be disastrous.

Come over a bit.

So there'll be six ropes coming up

to be able to lift it and hold it steady...hopefully.

With the tide coming in and the sun setting,

we couldn't cut it any finer.

OK, right. Whoa! Whoa, whoa, whoa.

Finally, the skull is safe.

Brilliant, Rob.

Well done. Well done.

THEY CLAP

Yeah.

It's amazing.

It's a dream come true. And I'll tell you what,

I don't think anyone would ever believe we could've done it.

Three weeks ago, it was buried in a cliff face.

We found the top food chain predator,

and now we're bringing it back to life.

And this will be one of the best that's ever been found.

Hey! Hurray! Good on you.

Oh! None of that.

Go on. Oh, get off, you little devils!

Oh, dear. Oh, dear.

It's out. The next stage starts.

The skull is transported to Steve's workshop.

The painstaking task of removing the stone from around the skull

so that it can be examined in detail...

..can at last begin.

After the heavy work of the dig,

this stage requires a delicate touch.

First, Steve removes the rocks surrounding the fossil...

DRILL WHIRS

..so that the fragile area of the skull can be strengthened.

Then, using an air abrasion tool,

he starts work to reveal the more intricate details

about the anatomy of this extraordinary animal.

This giant sea monster,

after 150 million years,

finally begins to emerge from the rock.

And I have the privilege of coming to see this whole skull

for the first time.

So here it is.

And it's enormous.

I am meeting Dr Judyth Sassoon,

a palaeontologist, who has studied

pliosaur specimens for decades.

Does it still take your breath away as it takes mine?

It is a most astonishing specimen, David.

I'm very pleased to be part of the work on it.

What insights can Judyth give us

into the life of this ancient monster?

How is it coming along?

What sort of detail can you get from this,

which you never knew before?

Steve Etches has been working on it now for several months

and has made some fabulous progress.

We're seeing, as it's being prepared,

gradually, more and more detail being revealed.

So far, we have some information

about its senses.

Really? Was their eyesight good?

There are indications that, in fact, it could have been.

The eyes themselves were quite important

for this animal.

One of the reasons is the position itself.

The eyes are on the side of the head,

more or less in the middle,

so not too high and not too low.

This important feature of the skull may suggest

how our pliosaur hunted in the open ocean.

The position of the eyes in living animals varies

according to the way in which they hunt.

Dolphins are pursuit predators.

Their eyes are placed on the side of their heads,

which gives them panoramic vision...

..enabling them to attack their prey with great accuracy.

Ambush predators, such as crocodiles,

have eyes higher up on their heads...

..so they can remain just below the surface

with only their eyes above water

and judge when to attack.

Our pliosaur seems to have had

something in between...

..with an eye position that not only enabled it

to pursue prey through the water with accuracy,

but alternatively surprise it by attacking from below.

And there is another remarkable feature,

which could tell us more about where our sea monster may have hunted.

We talked about eyes. There's also another interesting structure,

which is the parietal eye.

In many reptiles, this still exists.

When it is present in terrestrial animals,

it has a full eye structure, like the lateral eyes,

and is light sensitive.

The parietal eye on the top of the head

is something of a puzzle.

It's known as a third eye

and is still found in a few living species.

It apparently helps an animal to regulate its body clock.

The pliosaur's parietal eye is thought to have had a lens,

a cornea and a retina.

Although its exact function is unclear,

it may have enabled our sea monster to gauge

which way was up when swimming at depth,

and potentially navigate deeper hunting grounds.

What other questions would you have wished the skull

to provide answers for?

I've already made some measurements on this animal,

and the proportions do seem to be different

from other pliosaurs that we know.

The skull is quite long-snouted,

but the position of the nose and the eye

and also of the crest

suggest that it is something else, something new.

A new species of pliosaur? Of pliosaur, yes.

A new species? Really? Yes.

I think it could be, yes.

The revelation that our pliosaur could be a new species

is truly exciting.

There are only eight recognised species of pliosaur...

..and this skull is certain to provide new scientific data

on the evolution of these mysterious marine reptiles.

I have to say, you take my breath away.

The detail, which you can deduce,

it is mind-blowing, I think.

And that's what palaeontology is about.

I used to think it was just a question of finding a fossil

and digging it out and saying how nice it was.

You've made it sound rather different.

DAVID CHUCKLES

In recent decades,

huge advances have been made

in our ability to study prehistoric animals.

And we can now investigate the predator power of our pliosaur

in more detail than ever before.

Paleobiologist Dr Andre Rowe is a world-leading expert

in 3D visualisation of fossils.

Using the latest technology,

Andre is carrying out the world's first surface scan

of a pliosaur skull.

So, right now, we're capturing

basically hundreds of thousands of images all at once.

The end result is a really nice-looking 3D model.

I think we'll be able to unlock a lot of mysteries

about what these sea monsters were doing,

and I'm really excited to see where it takes us.

Once the scan has been finalised,

I meet Andre at the University of Bristol

to discuss his findings.

Has he seen anything in the skull's structure

that shows our sea monster

had the power of a truly deadly predator?

There's some massive openings back here along the jawline.

Yeah. And that's good for muscles

to attach and bulge out.

There'd be a muscle running through there.

Yes, we have the pterygoid muscle group,

which is in a lot of big dinosaurs,

and it's integral to having a really strong bite.

And we have hypothesised that this particular pliosaur

is kind of the apex predator

in the Jurassic ecosystems it was living in.

Does the skull give you any information

about what animal its prey might have been?

The animal would have been so massive

that I think it would have been able to prey effectively

on anything that was unfortunate enough

to be in its space.

A popular hypothesis is that

these animals were actually ripping off

the limbs of other animals to disable them from swimming away,

and then kind of going in for a kill.

So this is really a top predator?

Yes. I have very little doubt,

just judging from how massive that skull is.

I don't see what could have possibly hurt it.

What size is that, actually?

So the actual skull itself clocks in

just a little under two metres.

Two metres. Longer than I am.

Yeah. It's quite a big boy. And that's just the skull.

The dimensions of a fossilised skull enable us

to estimate the overall size of an animal when it was alive.

And based on Andre's measurements,

our pliosaur could have been

up to an astounding 12 metres long.

Just from the sheer size of it,

just from looking at this animal and how big those pterygoid muscles

would have been at the back of the jaw,

the animal would have delivered a devastating bite, no doubt.

A powerful bite is vital to the success

of any marine predator.

Scientists are able to estimate

how much force an animal can exert

when biting into its prey.

And great white sharks have one of the strongest bites,

at around 10,000 newtons.

But how do you work out the bite force of a creature

that became extinct millions of years ago?

Professor Emily Rayfield is a world-renowned palaeontologist,

who specialises in skeletal mechanics.

Using the model created by Andre,

Emily has assessed the bite force of our pliosaur.

So this is a 3D print, a model.

It's not full size, though.

It's just over a third of the size of the actual animal.

These large openings are the spaces in the skull,

which would have been filled with jaw-closing muscles.

So you can estimate the force of the bite

from the size of those muscles. Exactly. Yeah.

We can get an estimate of that from here.

We know that muscles of a certain...a certain size,

a certain area, are capable of generating

a certain amount of force.

Saltwater crocodiles have got

the largest ever bite force measured,

and they're up to about 16,000 newtons.

And these? So our pliosaur here,

from the estimations that we've made,

has a bite force that's about twice the size of that,

of the largest saltwater crocodile that's ever been measured.

And it's in the region of around 32,000 newtons.

So this is the most powerful biter

in the sea that ever has been, or that we know of?

That we know of, absolutely. Yes, definitely.

If you're looking at kind of statistics

in terms of car-biting metrics,

I'm pretty sure it could probably bite through a car.

So it's a monster?

Absolutely. BOTH LAUGH

The evidence gathered from the skull so far

suggests that this pliosaur

had the jaws, teeth and senses of a highly successful hunter.

Its long snout, short neck and streamlined skull

enabled it to move easily through the water.

But what else helped our enormous sea monster

to power through the Jurassic seas

fast enough to catch its prey?

Pliosaurs were unique in the natural world,

as they had four almost identical wing-like flippers.

How pliosaurs used their flippers

has been debated by palaeontologists for decades.

But, in recent years, scientists have been able to use

computer modelling to finally solve this mystery,

and it appears that these giant sea monsters

swam in a way that is surprisingly similar

to a very different type of animal -

one that is alive today.

Woo-oy!

Ha!

Penguins may appear somewhat clumsy

as they waddle around on land,

but once they're underwater,

they move very differently.

These are Humboldt penguins, and they're excellent swimmers.

Their streamlined body shape and their oily feathers

enable them to reach astonishing speeds

of up to 30mph.

But a key factor behind penguins' speed

are their flippers, which, underwater, act like propellers,

driving them forward and increasing their speed dramatically.

In slow motion,

you can see that the penguins are using

a lift-based underwater flight movement,

twisting their wings as they flap

and propelling themselves forward on the upstroke

as well as the downstroke.

As strange as it may seem,

it's thought that pliosaurs would have moved

in a very similar way.

But, of course, pliosaurs were enormous,

and most large animals

are relatively slow moving.

So as an apex predator,

how could this huge creature manoeuvre itself fast enough

to catch its prey?

To find out, I've come to the Hydrodynamic Laboratory

at Imperial College London,

where Dr Luke Muscutt is studying

the locomotion of pliosaurs,

using a rather unusual research tool.

How did you first become interested

in the way that pliosaurs swam?

It's the only animal that we know of

that has four large flippers.

So the question is, how did they use them?

The fossils of the pliosaur

show that the flippers were very much like wings.

So what I found was that the hind flipper

can actually operate at a much higher thrust

and at a much higher efficiency,

because it's utilising the wake of the flipper in front of it.

We can see a similar effect

in the flight of migrating birds, such as geese.

When geese are flying in formation,

each bird benefits from the uplift created

by the one in front of it,

so that they fly in a very energy-efficient way.

SQUAWKING

So you can think of the pliosaur as almost two birds,

one flying behind the other,

and the back one is benefiting from the one in front.

That's an extraordinary parallel, yes!

The hind flipper has increases in thrust and efficiency

of up to 40%.

Ah!

So this would have increased the swimming speed

that pliosaurs would have been able to achieve

and increase the number

of different things it could eat.

To take his research to the next level,

Luke has built a robot

to study the swimming pattern of pliosaurs

more accurately than ever before.

So what more information do you think you can get

from this model?

This robot enables me to test the complete animal.

How fast something can move is an absolutely critical part

of what that animal is,

and it tells us what animals it could have eaten,

how far it might have been able to travel...

All sorts of questions come back down

to its locomotion ability.

Have you estimated a speed that this might produce?

Well, I've only finished building this yesterday.

Oh, really? So, so far, I haven't

actually ran the experiments yet.

If you'd like to have a go, you're more than welcome to...

Yes. Oh, show me. So if you just move this joystick

sort of upwards further.

So this is how the pliosaur would have swam.

The flippers move primarily up and down.

It's much more like a bird flies.

Luke and his team set up the robot for a test swim,

and they entrust me with its maiden voyage.

If you'd like to take the control...

There we are. It's off.

I suppose, actually, that's only a model,

but if it was full-sized, it would be going quite fast.

Indeed. You can just imagine it chasing after a smaller ichthyosaur.

Luke's research is so new, it's yet to be published,

but it's helping to provide a new perspective

on these extraordinary animals.

Large marine predators, like orcas,

can swim at great speed through the ocean.

What speed might our pliosaur,

with its four flippers,

have been capable of?

Estimates suggest that they could have accelerated

up to 30mph,

making them one of the fastest animals in the Jurassic seas.

This skull is not only helping us to understand more

about the lives of these giant sea monsters,

but also allows scientists, like Dr Andre Rowe,

to visualise the Jurassic world as never before.

So often, I've been involved in looking at fossil skeletons,

and the skull... Unless the skull is there,

you're really missing an awful lot of information.

We are lucky to find this as the first thing.

Yes, I am very biased,

since I study feeding and teeth,

but I think the majority of information

about an animal you can get from its skull.

Yeah. The brain, the teeth, what it was feeding on,

its maximum body size if you have the whole skull.

It's just a treasure trove of information.

And we're very fortunate to have the whole thing.

One of the reasons why I love the UK is because it's got

such a great collection of marine reptiles.

Delighted to hear it.

I mean, in America, we've got our big tyrannosaurs

and our triceratops, but the UK is great for marine reptiles.

Well, we did discover the dinosaurs.

Yes, the science of palaeontology did originate here.

How would it compare with T-rex?

I imagine it would be pretty comparable.

They were kind of both the respective apex predators

in their ecosystems.

So I have no doubt that this was

sort of like an underwater T-rex, if you will. OK.

Let me ask you the million-dollar question.

In a battle between T-rex and our pliosaur,

who's going to win?

As much as it pains me and brings a tear to my eye to admit it,

I think my T-rex is going to lose this fight.

And then, millions of years later,

an American palaeontologist will envision this scene

and break down into tears. DAVID LAUGHS

Bringing an enormous predator back to life

after 150 million years

is no easy task.

But restoring this giant skull is a labour of love

for Steve and his team.

Almost a year after the skull was discovered,

I returned to Kimmeridge to see how they're getting on.

My goodness.

It is absolutely magnificent.

It's astonishing.

It's bigger than a T-rex.

Is it? Yeah, yeah. What, the skull? Yeah.

Yeah, bigger than any T-rex ever found.

David, now what we've done, since you've come here last,

is we've... I've air penned off all the mudstone

and then air abraded it. Now, the air abrasive machine

cleans out all these little voids,

and you see every little detail,

every suture, where the bone join together,

you can see every detail. That's what we really wanted.

So the teeth here have been basically tumbled on the beach,

and the shingle had worn away all the crowns.

So we're going to do a bit of dentistry on them.

So we've got this tooth, which has been scanned,

and then we're going to increase or decrease it,

and then add all the teeth back in position

to show people what it actually looked like.

You must feel, looking at this...

I mean, I know it was a huge amount of work to get it out.

We never thought we'd get it, to be honest.

I'll be honest with you.

Well, it's certainly a triumph.

Yeah, quite an emotional moment for everyone.

I'm sure. Yeah.

A sensation.

Once the pliosaur's dagger-like teeth are added...

..the picture is finally complete.

Our journey of discovery has shown

that this sea monster was one of the greatest predators

the world has ever seen.

And we can now visualise more accurately than ever

how it may have hunted in the Jurassic seas.

Ichthyosaurs,

swimming in groups along the coast...

..concentrating on hunting their prey...

..unaware that they themselves are being stalked.

On their trail,

our pliosaur uses its highly-tuned senses

to launch an attack.

In the chase, its four flippers,

each two metres long,

drive it through the water at great speed.

Splitting the shoal, it isolates its target.

Our sea monster's primary weapons

are its 90 razor-sharp teeth...

..with which it slices through its victim's flesh.

The impact alone may have been enough to kill.

But with a bite force twice the strength

of any animal living today,

its prey had little chance of survival.

From a chance discovery on a beach one morning

to the painstaking restoration

of such a rare and impressive specimen,

the story of this fossil is one of skill, dedication

and of fascinating scientific discoveries

made along the way.

We've been given a unique insight

into the life of our pliosaur

that swam in the Jurassic seas 150 million years ago,

but we're also reminded

that there is still so much to learn

about these extraordinary prehistoric animals.

And I, for one, will never tire of discovering more.

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