Planet Dinosaur

This is one of the most awesome dinosaurs ever discovered.

Meet Spinosaurus,

a truly amazing predator that lived 95 million years ago.

In the dinosaur world, this is the Terminator,

at a stunning 17 metres in length and 12 tonnes in weight.

Spinosaurus is one of the largest predators

to have ever walked the planet.

It lived in North Africa.

Here, it's roaming a swamp,

but this hunter's favourite prey lived elsewhere.

HISS

Spinosaurus's meal of choice was fish, not meat.

This is a dinosaur that loved to hunt in water.

Standing in the river shallows, Spinosaurus plays a waiting game.

It's on the lookout for one of these.

Onchopristis, a giant eight-metre long swordfish.

There's enough fresh sushi there for a whole Japanese restaurant.

You can find this kind of hunting going on in the wild today.

This grizzly bear loves a bit of raw fish too.

He and his mates know that thousands of juicy salmon are swimming

up river, and they're waiting for a meal to come their way.

And their super-quick reactions mean they can catch this fish in mid-air.

But how do we know that Spinosaurus was as partial to fish

as that grizzly bear?

By looking at the evidence, that's how.

These are the tooth sockets in a Spinosaurus's jaw.

It was found in 2005 in North Africa.

Stuck in one of the sockets is a tiny piece of backbone

from another creature.

This spino clearly didn't brush his teeth before he went to bed!

That bone fragment was from a swordfish, possibly Onchopristis.

These juicy fish were one of Spinosaurus's favourite foods.

And, a bit like a bored angler,

Spino would spend hours waiting for these tasty river treats to swim by.

Here was a beast that loved poking its snout into a fast-flowing river.

And Spinosaurus's way of catching fish is really clever.

Its secret lies in that snout.

It has lots of small holes in it that are very similar

to those of a crocodile.

In a crocodile, these snout holes contain special sensors.

These help the croc to feel small changes of pressure

caused by other creatures disturbing the water nearby.

That signal is one of the ways it zeroes in on prey.

And dinosaur experts believe that the Spinosaurus had sensors

like the crocodile, an amazing ability that meant

it could strike at these onchopristis

without even seeing them.

Take a look at this amazing creature.

A flying monster, its name is Hatzegopteryx.

This is a kind of prehistoric flying reptile called a pterosaur

and it's one of the largest flying creatures ever known.

This mind-blowingly massive beast

patrolled the skies 65 million years ago.

At that time, Europe was made up of lots of islands, one of which

was called Hatzeg, which is how this monster gets its name.

And it really is a monster.

Hatzegopteryx was over five metres tall

and had an enormous ten metre wide wingspan.

That's as big as this modern jet fighter.

Hatzegopteryx was an incredible flying machine.

But it preferred to hunt on the ground.

It could gobble up these much smaller herbivores with ease.

Usually, long-necked sauropods, like these magyarosaurs,

were the biggest beasts in the dinosaur world.

Here, though, they're dwarfed by Hatzegopteryx.

How do we know that a flying reptile could actually get this big?

By taking a look at the evidence, that's how.

These are the fossilised footprints of a pterosaur,

very like Hatzegopteryx.

Discovered in 2002, they measure a massive 35 centimetres across,

proving that these creatures could be huge.

Imagine, if the hatzegopteryx were around today,

it would be three times bigger than the world's largest flying bird,

the wandering albatross.

And when it landed on the ground, it would be as tall as a giraffe.

Take a look at this condor from South America.

This bird glides a bit like Hatze.

A condor's wings take advantage of warm air currents called thermals.

They help it stay in the air for hours on end.

Dinosaur experts believe pterosaurs like Hatzegopteryx

could do the same.

If you thought Tyrannosaurus rex was an impressive dinosaur,

take a look at this prehistoric predator.

This is Carcharodontosaurus.

ROAR

Its name means "shark-toothed lizard".

This monster grew up to 13 metres long.

An adult weighed a hefty seven tonnes.

It ruled the roost in North Africa 95 million years ago.

ROAR

Carcharodontosaurus was a carnivore,

and a whole ton heavier than T-Rex.

How much meat do you think a killer of this size ate each day?

The amazing answer is that a full-grown carcharodontosaurus

needed to eat a whopping 60 kilograms of meat every day

just to survive.

That's like having 480 hamburgers every day.

Now, the carcharodontosaurus liked to hunt

by creeping up slowly on its prey.

But amazingly, for such a large beast,

we've recently discovered that it could really move it too.

Watch this.

Over short distances, this hunter's explosively powerful legs

could get it running up to 20 miles an hour.

That meant it could catch lighter prey like this ouranosaurus.

So, where would you have found one of these ruthless killers?

Most of the 95 million-year-old carcharodontosaurus bones

have been found in various sites across North Africa.

Life for these big killers was a constant battle. For food...

For territory...

For dominance over other carcharodontosaurs.

ROAR

But how can we tell this kind of head-to-head battle went on?

By closely looking at the evidence, that's how.

This is a recently discovered lower jaw bone.

It came from a meat-eating dinosaur.

It's big, nearly half a metre long, and the exciting bit?

Two bite marks.

The size and shape of the tooth marks show that another dinosaur

of the same species had sunk its teeth into this jaw.

For a carcharodontosaur to dominate its patch,

it first had to see off rival carcharodontosaurs.

And that's often the way it still goes in the wild.

This frilled lizard from Australia has found a good feeding area

with lots of tasty insects.

So when another male lizard of the same size enters its patch,

battle commences.

HISSING

And goes on for a long time.

ROAR!

But when two seven-tonne carcharodontosaurs went at it,

I wonder what kind of destruction that would cause.

Well, with the help of some power tools and a chunk of steel,

I'm about to find out.

It's hard to imagine the damage

these carcharodontosauruses would've caused

if they start throwing their weight around.

But to get an idea, we've built a carcharodontosaurus foot.

It's been very specifically shaped to match the fossilised footprints

that have been found from the real thing.

It's made of steel, not flesh and bone,

but hopefully it's going to be strong enough for the task ahead.

You see, I want to attach this to something that can provide

the power and weight that would've been there

with a real carcharodontosaurus.

Rich!

'And this big digger is it.

'A huge hydraulic excavator.

'35 tonnes of steel on caterpillar tracks.'

Rich the driver assures me that this enormous excavator

can get my carcharodontosaurus foot to step down

with the seven tonnes of force

that the real thing would have applied with every stride.

Want to grab the back end? This is heavy, to say the least.

Ah! Cheers.

Thing is, first job is to attach it to this digger.

That's attached.

Now, let's see what kind of impact a dinosaur like this would have had.

I need something else made of steel

for my carcharodontosaurus foot to tread on.

So, I've got myself a scrap car.

Now, obviously, they didn't have those 95 million years ago,

but it's here to represent the unfortunate dinosaurs

that may have got in the path of the mighty carcharodontosaurus.

Right, Rich, can you give this a big, seven-tonne stamp?

Erm...

It didn't really stand a chance.

And I think that's probably what a lot of dinosaurs

that hung around North Africa 95 million years ago felt.

Because weight is a massive advantage

in the battle for dominance.

And the carcharodontosaurus carried a lot of weight.

And this one's angry.

'I'm not sure that that's the kind of thing covered by car insurance.'

Meet Nothronychus.

A strange-looking dinosaur with a potbelly.

It lived in swampy jungles like this 92 million years ago.

Because it walked upright on two legs,

Nothronychus has the classic look of a meat-eating dinosaur.

But it's actually a vegetarian.

It's one of a weird group of dinosaurs called theriznosaurs.

Twice as tall as an adult human, it had a lengthy neck

and powerful legs.

It used its very long, curved claws to pull down branches,

to get nice, juicy leaves to eat.

In fact, its name means "sloth-like claws".

And here's why.

Northro's claws are very like those of this bizarre-looking creature -

the sloth.

This gentle, tree-dwelling mammal lives in South America.

It uses its claws to grab

and eat leaves in a very similar way to how we think Nothronychus did.

Unlike sloths, though, Nothronychus had to be ready to defend itself

against some dangerous predators.

In these same swamps is an eight-metre-long tyrannosaur.

A fearsome carnivore from the same family of dinosaurs

as the famous T-rex.

And this tyrannosaur fancies some nothronychus for dinner.

And it's at times like this

that those claws become weapons of self-defence,

making these potbellied beasts a match for the mighty tyrannosaurs.

Nothronychus is just as powerful

and aggressive as these killers.

And that's because they're actually close relatives.

So, if they look like a carnivore and they fight like a carnivore,

how can we be sure that they were actually herbivores?

By taking a look at the evidence, that's how.

In 2001, the bones of a dinosaur very like Nothronychus

were discovered in the USA.

Amongst them were fossil teeth.

Their shape showed they were designed for eating leaves,

not meat.

Nothronychus, just like these tyrannosaurs,

started off as a meat-eating dinosaur.

But over hundreds of thousands of years,

Nothronychus changed its eating habits.

It still looked like a carnivore, with its upright stance,

but now it lived off plants.

'Let's find out more about the Nothronychus diet

'in the Dinosaur Workshop.'

It doesn't matter whether you're a bunch of hungry tyrannosaurs,

a nothronychus, or me, a human being. You've got to eat to survive.

Now, for a human being like me,

every day I'm going to consume something like this.

Rice, pasta, egg, fruit and vegetables.

It's got add up to enough energy for me to do what I need to do.

But what would a one-tonne dinosaur have to eat?

Now, remember,

Nothronychus is descended from a long line of big carnivores

and they ate meat. Lots of it.

A typical one-tonne meat-eater would be getting through

around about ten kilos of flesh every single day.

So, that's like this lot and, probably, my leg into the bargain.

Now, that may look like an awful lot to consume

until you remember Nothronychus is trying to get

this amount of energy just by eating plant matter.

And vegetation just isn't as energy-dense as meat.

You've got to roughly eat five times as much to get what you need.

So, every day, a nothronychus would be trying to get through that.

And probably that. And probably that. And maybe that too.

It is an absolute stack of vegetation to chomp your way through

every single day.

Which is probably why Nothronychus was renowned

for its large potbelly.

It had an awful lot to fit in. But why would it bother?

Well, by eating vegetables, it didn't have to compete

with all the large carnivores eating meat.

Easy, tiger.

This is Argentinosaurus.

A massive, plant-eating dinosaur

that lived 95 million years ago in South America.

They were huge. But their babies were tiny,

weighing only five kilograms.

That's about the same as a one-month-old human child.

But fully-grown Argentinosaurs could weigh as much as 75,000 kilos.

That's heavier than the combined weight

of all the children in a typical primary school.

This dinosaur is the largest creature

known to have walked our planet.

Being so big meant that any other dinosaur that got too close

to Argentinosaurus could be in real danger.

It's almost impossible

to comprehend the size of these enormous creatures.

Maybe this argentinosaurus leg bone could help you get an idea.

It weighs half a tonne.

It's one of many found in Argentina in 1993.

Just that single lower leg bone, which would be the shinbone

for a human, is, incredibly, taller than an average 13-year-old.

Or, to put it another way,

a fully-grown argentinosaur weighed as much as ten elephants.

Meet Epidexipteryx.

A very strange-looking, pigeon-sized creature

that you would have found in lush forests like this

154 million years ago.

This dinosaur lived in Asia.

It was small, only half a metre long

from its head to the tip of its tail.

And it had a bird-like skeleton,

covered in feathers.

Epidexipteryxs were dinosaurs like no others.

Everything about them is weird.

The tongue-twisting name, the long tail feathers,

sticky-out teeth,

and, especially, those spindly fingers.

Those fingers, though, are for more than just climbing trees.

Watch this.

That third finger on both its clawed hands

is much longer than all the others.

It's a tool Epidex uses in a very clever way.

For getting at food hidden inside the tree.

Amazingly, there is actually an animal today

that uses the very same weird method for getting its dinner.

This is an aye-aye.

It's a small mammal that lives in Madagascar off the coast of Africa.

Just like Epidex, it has a very long third finger.

It taps on the tree and listens.

When it hears something inside, it scrapes away at the bark,

hoping to get some juicy insects to eat.

'Time for me to turn myself into a very strange creature.'

Ha-ha!

Epidexipteryx had probably the weirdest set of hands

I've ever seen.

It kind of had these two shorter talons

and then this one ludicrously long finger.

Its way of life was to climb trees and eat grubs.

Now, what I want to do is get an idea

of what that would have been like,

and the strengths and weaknesses of the features it had evolved.

So, I'm going to set off as a normal person

to live the life of an epidexipteryx.

Got myself a jungle, here,

hopefully there's some food in there somewhere.

I'm going to see if I can find it.

When it comes to climbing, our hands are actually pretty good.

We've got sort of short, stubby, strong fingers that can grip

and move our way up through trees pretty effectively.

But what about foraging for food?

If I wanted to find maybe a big, fat, tasty grub to eat,

what are my hands like then?

Ha-ha. In here. I see some food.

There's a little grub in this log.

The problem is, our strong, stubby fingers haven't got the length

to get into little nooks and crannies to pull grubs out.

What I need is a new set of hands.

On with my epidexipteryx gloves.

Argh.

What I find, climbing as an epidexipteryx,

I've got to climb in a different way.

Because I've only got three fingers, I've got to use my feet more

cos, even with my fingers,

only two of them are any good for gripping.

This third one feels like a positive disadvantage on the climbing front.

But I'm getting used to it.

Now, I'm going to get up here, towards where the food is.

Now, now I can see this big fella coming into its own.

Cos that little nest of grubs are now all within reach.

Oh, got it. Come on. Look at that!

Now, I really am beginning to enjoy life as an epidexipteryx.

There are so many strange things about Epidexipteryx,

aren't there?

I mean, how can we be sure that a dinosaur like this really existed?

By taking a look at the evidence, that's how.

This extraordinary fossil was discovered recently in China.

It shows a whole epidexipteryx. Its bird-like appearance is clear.

As are its odd-looking teeth on its skull.

You can even see the long tail feathers.

Epidexipteryx was about the size of a pigeon.

But a pigeon's feathers help it to fly.

The feathers on this dinosaur were for display.

In other words, showing off.

This is one of the strangest dinosaurs

to have walked our planet.

Meet Gigantoraptor.

A breathtaking creature,

with a body like a huge, overgrown ostrich,

and a head with a fearsome, parrot-like beak.

It's the largest feathered animal ever discovered.

Gigantoraptor was one-and-a-half tonnes in weight

and a massive eight metres long.

It had vicious, dagger-like claws,

and lived 80 million years ago.

Gigantoraptors were to be found in Asia,

roughly where you'd find Mongolia today.

They come from a family of dinosaurs known as oviraptorids.

But Gigantoraptor was by far and away

the biggest member of this strange family.

How do we know such an odd creature ever existed?

By taking a look at the evidence, that's how.

This is the Gobi Desert in Mongolia, Asia.

In 2007, the bones of a gigantoraptor were discovered here.

They were huge. 35 times bigger than any other of its close relatives.

It's their sheer size that's incredible.

It looks a bit like an ostrich.

But it would need four ostriches standing on top each other

to match the height of a gigantoraptor.

We know that gigantoraptors had feathers

because they've been found on the fossils

of other closely-related dinosaurs.

But Gigantoraptor's feathers weren't for flying -

nor were they for keeping warm.

These were feathers for display - especially for attracting a mate.

Here, a male and female gigantoraptor

are doing a kind of dance.

It's a bit like showing off your best dance moves

at the school disco.

Now, if that sounds just too far-fetched,

take a look at these grebes.

Just like the gigantoraptors,

they're carrying out what's called a courtship dance.

They move in time, display their feathers

and copy each other's movements.

The aim is to find and, hopefully, attract a mate.

Gigantoraptor's similarity to birds really stands out

but there's more to this resemblance than feathers and beaks.

That's because they laid eggs.

This is how all dinosaurs gave birth.

What's special about Gigantoraptor is that it stayed with its eggs,

protecting them.

Here, a pair of gigantoraptors defend their nest

against an attack from this predator - Alectrosaurus.

Danger over.

The mother gigantoraptor settles back down on her nest.

'Meanwhile, in the Dinosaur Workshop,

-'I'm

-hatching

-a very

-egg-citing

-plan.

'Yeah, er, sorry.'

There is one thing that all dinosaurs have in common.

They lay eggs.

And, in the case of the gigantoraptor,

eggs like I have never seen before.

To show you how odd they are, let's first look at more familiar eggs.

That's a chicken's egg. We all know what these are like.

They're three centimetres long. We have them for breakfast.

This is an ostrich egg.

This is the biggest egg that's laid on the planet in modern times.

It's a pretty good size and it comes from a pretty good-sized bird.

And this is a genuine dinosaur egg.

Or, at least, a fossil of one.

This would have been laid in muddy ground about 70 million years ago.

And, over that time, the mud has turned into rock

and the egg has turned into a fossil.

And this is our gigantoraptor egg. I say "ours" because we've made it.

But we've made it very carefully,

to be the right size, shape and strength

to match fossilised gigantoraptor eggs that were recently found.

These eggs took about 80 days to hatch.

Now, that is a long time

for it to be exposed to potential predators.

So, they would have to have been made pretty strong. How strong?

Let's find out.

Naturally, my fellow dino engineers, Andy and Jim,

are filling my gigantoraptor egg with white and yolk.

This is my egg-strength testing machine.

Gigantoraptor egg is up there.

Whatever weight gets loaded on here gets felt by the egg up there.

When this weight here gets too much for that egg...

First...

These bags weigh 25 kilos.

And the egg doesn't care about that.

Looks like I might have to get involved, here.

Not in my best T-shirt.

I'm 75 kilos.

100 kilos

on our gigantoraptor egg.

More weight.

That's 125 kilos.

Now, dinosaur experts did reckon that these eggs

would probably have taken that,

but they weren't sat underneath the egg at the time. More weight?

'This gigantoraptor egg is living up to its tough reputation.'

That's 150 kilos.

CRACK

LAUGHTER

Argh!

Argh!

Right. Well, that's a nice piece of science,

cos that egg pretty much fitted

with what the dinosaur experts reckoned the Gigantoraptor egg

would have taken.

We're going to look at the bite strength

of three very powerful dinosaurs.

Allosaurus.

Majungasaurus.

And Daspletosaurus.

All of them are big predators with terrifying jaws.

Just imagine them clamped tight round your leg.

How much force do you think it would take to prise them back open?

'Let's find out in the Planet Dinosaur Files Workshop.'

Now, obviously,

a dinosaur's jaws are what's really scary about these beasts.

But I want to know is just how powerful those jaws are.

To do that, I've built my own dinosaur jaws.

My first set of experimental jaws are going to recreate

the bite of an allosaurus,

a muscle-bound, meat-eating dinosaur that lived 150 million years ago,

roughly where the USA is today.

This is my allosaurus.

And this is what's driving the bite of the allosaurus.

It works off compressed air, like this.

I'm using air to force my jaw shut

by squeezing it into this rubber tube at high pressure.

At the moment, I've got it set to what dinosaur experts reckon

is the muscle strength in an allosaurus's jaw.

Now, I figure a good test to see how powerful a bite these fellas had

is to stuff something in its jaws,

get them to clamp down with full biting strength

and then see what it takes to wrestle the jaws back open.

Chris, do want to give that full allosaurus strength?

Right, it's now clamped down on my trusty broom. Can I get it back?

No.

It turns out there's no way...

an 11-stone bloke...

..can get the jaws of an allosaurus open once it's bitten down.

What about two blokes?

Obviously, out in the wild, that would be a very dangerous manoeuvre.

Right, see if we can get this open. Oh, my life!

It's not easy.

That is an incredibly powerful bite,

but two full-grown blokes

can just about wrestle open the jaw of a full-grown allosaurus.

Here's another powerful prehistoric carnivore.

This is Majungasaurus,

a scavenging predator that lived 70 million years ago

on the island of Madagascar, off the east coast of Africa.

Although it was big, weighing well over a tonne,

Majungasaurus was actually smaller than Allosaurus.

So, how does it compare in jaw power?

'Back to the dinosaur workshop.'

Time to test out the majungasaurus jaws.

Now, I've got the same powerful artificial muscle as before,

but I've slightly reduced the head size.

These animals were a little bit smaller than the allosaurus,

but they had a powerful reputation.

Jaws are set to majungasaurus strength.

Although ordinarily a vicious meat-eater,

it's time the majungasaurus had one of its five a day.

I think it quite likes them!

What will it take to prise open the mouth of a majungasaurus?

-Ready?

-Yeah.

It's slightly mad just how hard that bite is.

There's absolutely no way that both of us are getting that open.

I think this needs something a bit more than human.

'Where manpower fails, maybe van power will succeed?'

Are you good? Start taking that away.

Have you got any more?

Yes, you've got it!

Well, there we go.

The majungasaurus - too much for a man,

about right for a man and a van.

Time to ratchet up the power factor with my third and final dinosaur.

Meet Daspletosaurus.

This intimidating beast lived 75 million years ago

in what today is Canada.

Adult daspletosaurs could be up to nine metres long

and three tonnes in weight.

That's bigger than Allosaurus and Majungasaurus put together.

So, how will the jaws of this hefty hunter

compare with our other two predators?

This is my daspletosaurus.

Even in dinosaur terms, these things were veritable monsters.

They were like the granddaddy of T-rex.

Now, as you can see,

it's a much, much bigger animal

than either the allosaurus or the majungasaurus.

In order for us to replicate that bite force with our model,

we had to take the whole rig right up to maximum.

Chris, do you want to power it up?

That's a concrete brick wedged in our daspletosaur jaws.

Right. That's down pretty hard.

So, what will it take to force open the jaws of a daspletosaurus?

-Jim, shall we try by hand?

-OK, ready?

Right, it's kind of obvious that this thing

is well beyond the means of human power.

But the van's not doing the trick either.

That's pretty shocking,

because we went to great lengths to build this to accurately reflect

what experts think these dinosaurs were capable of.

Headline news -

you can't even open the jaw of a daspletosaurus with a van.

I think we need some professional help.

What I've got is a daspletosaurus biting down at full power.

And you're sure your little dinosaur

-is going to be more powerful than my big dinosaur?

-I'd imagine so.

What do you normally use those for?

It's a hydraulic spreader, mainly used for car crashes,

so we can rescue people stuck in cars.

To get these in here,

-I'm going to have to do a bit of dentistry, aren't I?

-I'd say so.

Cleanliness is important in dentistry.

Don't worry, big fella, this shouldn't hurt at all.

Stay being brave!

Sparky, can you do a job for us?

OK. Fire it up.

So, will these jaws finally meet their match?

'It's taken that super-powerful fireman's gadget,

'capable of shifting the weight of two double-decker buses,

'to get those jaws open.'

I'm seriously impressed.

I don't want to hold you up from fighting fires.

-Thank you ever so much.

-Cheers.

Looks like we've finally overcome the daspletosaurus.

It appears as though normal people can't do it -

if Daspletosaurus bites down on something,

better call the fire service.

'Down at my local swimming pool,

'we're going to look at the swimming technique

'of three prehistoric predators.'

Kimmerosaurus.

Sarchosuchus.

And Predator X.

First up is Kimmerosaurus.

This sea beast roamed our oceans 150 million years ago

at a time when the whole continent of Europe was covered in water.

Kimmerosaurus was a type of prehistoric sea creature

called a plesiosaur.

It was six metres long - the length of a killer whale -

and this ocean predator liked to hunt sharks.

Kimmerosaurus lived millions of years ago,

but it swam in a way familiar to creatures in our oceans today.

These sea-lions have four fins,

like Kimmerosaurus.

And, a very similar swimming technique.

And look at these penguins.

We all know those stubby wings don't get them airborne,

but once they go underwater, it's almost like they're flying.

Look how nippy they are.

'Now, let's head to the swimming pool to find out more about

'how Kimmerosaurus moved through the water.'

So, how good was a kimmerosaur's swimming technique?

Well, I'm going to try and find out in this swimming pool.

I can swim backstroke, front crawl and things like that,

but I haven't got the equipment to swim like a kimmerosaurus.

So, we've built this.

It may look a bit big and bulky, but actually,

it's only about half the size of the real thing.

And a kimmerosaurus didn't swim front crawl, like that.

The kimmerosaurus used wings.

What they used to do was sort of flap these wings in the water

to propel themselves at great speed underwater.

Jim and I, the muscles of the kimmerosaurus,

can't spend much time underwater because of our lungs,

but we can operate these wings.

-Ready, Jim?

-Yeah.

-Let's go.

We're timing how long it takes our kimmerosaurus swimming model

to get down this 25-metre pool.

Just how good are those underwater wings?

That's pretty astonishing.

Just these four flapping fins have managed to get

well over a quarter of a tonne of boat and rider

down a swimming pool in less than 45 seconds.

Obviously, a real kimmerosaur would be a lot smoother,

because they swam under the water.

They didn't have a big, bulky boat with them.

I think it is a very effective swimming technique.

Our next prehistoric swimmer is this terrifying river beast.

Meet the king of the crocodiles, Sarchosuchus.

Its name means "flesh crocodile"

and it lived 95 million years ago in North Africa.

An enormous 12 metres long -

that's the length of a whole railway carriage.

Heavier than a fully-grown elephant,

weighing an astonishing eight tonnes.

Twice the size of any crocodile in the world today.

This is a super crocodile.

Sarchosuchus, like all crocodiles,

was perfectly adapted to living in water.

True, crocodiles do have to come to the surface to breathe,

but they've evolved to be able to spend

staggering lengths of time underwater.

If they're not moving, they can spend several hours

beneath the surface without needing to come up for air.

They also have a special way of swimming that's different to

sea lions or Kimmerosaurus, the plesiosaur we've already met.

A crocodile's body and tail moves in a sideways action,

making a kind of S shape through the water.

'Let's find out just how effective that method was in practice.'

OK, now let's see how quick it is swimming like a sarchosuchus.

First, I need a very long tail.

Next, I want to make myself look as frightening and sleek as possible.

And finally, to be a top predator,

you need to be able to see underwater.

That's it. Sarchosuchus.

Sarchosuchus swims in a very different style to Kimmerosaurus.

How will it compare for speed?

That is astonishingly quick.

That is twice the speed of a kimmerosaurus and the thing is,

once you get one of these big crocodile tails on,

you can feel the power in the water.

You can use every muscle in your body to propel yourself along

and that's why the sarchosuchus must have been

one of the most feared predators in prehistoric waters.

Here is our final aquatic contender.

Recently discovered,

it's so fearsome that even its name is terrifying.

This is Predator X,

a truly enormous monster.

More than 15 metres long and a massive 45 tonnes.

Nearly five times the weight of the largest known killer whale.

It had jaws more powerful than any dinosaur.

Predator X lived 150 million years ago

in the same seas as Kimmerosaurus

and it's likely that Kimmerosaurus

was top of the menu for this ocean monster.

Now, often in the water, smaller can seem faster.

And as Predator X is three times bigger than Kimmerosaurus,

you might think that Kimmerosaurus

would be able to outswim this huge hunter.

Let's find out if that really is the case.

Time to bring a bit of Predator X to the local swimming pool.

Now, in swimming style, he's pretty much the same as Kimmerosaurus -

four large fins flying through the water.

Significant difference - he's much, much bigger.

There's the little old Kimmerosaurus one,

here's the big Predator X one.

Whereas Kimmerosaurus was about the size of a killer whale,

this thing, in real life,

would have been about the size of this swimming pool.

So, how will our Predator X get on?

'Once we get those massive fins into a rhythm,

'Predator X eats up the water.'

Just over 30 seconds. This thing's quick.

It's not quite as quick as Sarchosuchus,

which was very swift off the mark,

but noticeably faster than Kimmerosaurus.

The fact is, the way it felt here,

Jim and I just don't have the power for water wings this big.

And the difference is,

real-life Predator X was a veritable monster.

It was like a 45-tonne torpedo and it had all the strength

it needed to drive its massive wings through the water,

giving it the ability to devour just about anything it wanted.

This is the island of Madagascar off the coast of Africa,

70 million years ago.

A family of scavenging majungasaurs, a mother and two youngsters,

are feeding off a carcass.

Suddenly, another big meat-eating dinosaur arrives on the scene.

Another majungasaurus.

It's a male, and he wants to muscle in on this feast.

Our majungasaur mum has her kids to think of. They need food.

But this male is greedy. He wants all that meat for himself.

He won't even let the youngster have the scraps.

Now, take a look at this fossil.

This is the tail bone of a majungasaurus,

discovered on Madagascar in 2003.

Take a very close look. There are some revealing marks on it.

What do you think those marks are, and how might they have got there?

Here's one possible answer.

They came from the teeth of another majungasaurus,

caused maybe during a fight between two of these dinosaurs

that has left the scars of battle.

But things aren't always what they seem.

Dinosaur experts discovered these were bite marks -

another majungasaur's bite marks.

But this didn't look like a fight between two angry predators.

This was one majungasaur eating the other.

So it seems that majungasaurs could be cannibals.

When the female majungasaur finally finishes off the male,

it doesn't go back to that carcass.

Instead, it starts eating the body of the male majungasaur.

If that seems shocking, maybe unbelievable,

then just take a look at our world today.

These insects are praying mantises. A male and a female.

They're mating.

But then the female starts eating the male's head.

Mantises, just like majungasaurs, can turn into cannibals

when they're hungry.

Meet Spinosaurus, a huge dinosaur.

17 metres long and 12 tonnes in weight.

This incredible predator lived 95 million years ago in North Africa.

You would typically find this dinosaur

standing in the shallows of a river.

Here, our spinosaurus has got its eyes on something in the water.

Now, take a look at this piece of bone evidence.

These are the tooth sockets in a spinosaurus's jaw.

It was found in 2005 in North Africa.

Stuck in one of the sockets

is a tiny piece of backbone from another creature.

How do you think that fragment of bone got into Spino's jaw,

and what type of creature might that bone have come from?

Well, here are four possible prehistoric suspects.

They're all creatures that lived in water.

There's Kimmerosaurus, Predator X,

Sarcosuchus and Onchopristis.

Which one is it?

Let's look at our suspects.

Well, both Kimmerosaurus and Predator X

lived 55 million years before Spinosaurus was around.

They're also sea creatures,

and Spino was a dinosaur that hunted in rivers, not oceans.

So, that rules them out.

And then there's Sarcosuchus, a giant prehistoric crocodile.

This reptile lived at the same time as Spinosaurus

and around the same North African rivers, but Sarcosuchus

was another massive predator,

too big for even Spinosaurus to take on.

That leaves just this creature.

Onchopristis, an eight metre-long sawfish.

It was a prehistoric river fish

that lived at the same time as Spinosaurus.

Spino, as we know, was a dinosaur that spent a lot of time by rivers.

Standing in the shallows, it would play a waiting game.

Usually, it would be on the lookout for one of these, onchopristis.

Palaeontologists, dinosaur experts,

are convinced this kind of creature provides our answer.

That mystery bone fragment came from a sawfish like onchopristis.

These juicy fish were one of Spinosaurus's favourite foods.

And a bit like a bored angler, Spino would spend hours

waiting for these tasty river treats to swim by.

Here was a beast that loved poking its snout into a fast-flowing river.

When it grabbed an onchopristis in its jaws,

it's easy to see how a piece

of the sawfish's backbone could get stuck in Spino's tooth socket.

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