Original subtitles

Nigel Marven.

A time-traveling zoologist,

and a man who has had his fair share of close scrapes with dinosaurs.

But the Earth has witnessed more terrible monsters than these.

What Nigel is about to learn about prehistory

is that no matter how bad things get on land,

the one thing you should never, ever do is get in the water.

In this adventure, Nigel will travel back and forth through prehistory

to visit seven different time zones and dive in the seven deadliest seas ever.

Each sea he visits will be more dangerous than the last.

With bigger, nastier predators.

Creatures it's hard to believe once lived on this planet.

And of course, he's saving the worst...

..till last.

Nigel's first stop in this perilous navigation through time

is a period called the Ordovician.

To get back there from the 21st century,

you have to go unbelievably far back in time.

Back before the Ice Age.

Before the first humans.

Before even the dinosaurs.

The Ordovician is a mind-boggling 450 million years ago,

so far back that plants have yet to evolve.

It's a world ruled by creepy-crawlies, and fantastically unsuited to humankind.

The atmosphere at this time, it's atrocious.

Much less oxygen and much more carbon dioxide than I'm used to.

Without this special air mix, I'd really feel sick and get bad headaches.

Just look around and you can see why the atmosphere is so different.

There's no life at all on the land.

There's no insects in the air, there's not even worms in the ground.

And most crucially of all, there's no plants.

There's not a speck of green.

The carbon dioxide in the atmosphere is not absorbed by them,

and they're not boosting the atmosphere with oxygen.

But it's a different story out there in the sea.

There's been life there for hundreds of millions of years.

And you can take it from me, evolution has produced some real monsters.

And now it was time to find one.

First, some bait. In the Ordovician, that's the easy bit.

With no land animals to scavenge the beach,

anything the sea spits up just lies here rotting.

An armor-plated fish.

Now, into shallow water,

to flush out an unpleasant little critter that I was going to be seeing a lot of.

A sea scorpion. One of the most grotesque of predators.

Look at that, look at the tail curling.

That's how they get their name,

but there's no venom in there, like their namesakes on the land.

You've got to be careful of those formidable pincers.

The scorpion gave me a graphic demonstration

of just how formidable its claws are.

It literally shredded the bait at my feet before moving on to bigger prey.

Argh!

Are you all right, Nigel?

Slashed my leg.

That's another scar for the collection.

As I found out, those sea scorpions are pretty fearsome.

But there's much bigger sea monsters - sea scorpions are not the top predators.

But to see the real big ones, I need a little more than a fish on a stick.

I'm gonna try with this. Looks like a giant woodlouse.

It's a Trilobite.

There's no relatives of this in the 21st century,

and there's up to 15,000 species.

They range in size from a millimeter in length to this big one.

This is about as big as they get, and I need one like this,

because I'm gonna use this like a fisherman with a fly,

and I'm going to try to attract a much bigger catch.

And all I need to do is to insert this camera into the carcass.

Now, if you're squeamish look away now,

'cause what I've got to do is pop out the eye of this Trilobite.

Here we go. Ugh!

There's so many surprises here.

The sun's setting, the evening's come and it's been so quick the day's flown by.

That's 'cause I forgot, in Ordovician times the Earth's spinning much faster

and that means that it's a 21-hour day, not 24 hours,

so a watch like this is useless here.

Look at that. It's gonna be dark very soon and we can't do anything more today.

Anything you do, you try to...

I'm hoping to dive with a sea monster. There's a special air mix in here.

If I breathed Ordovician air at pressure under the water, I'd become unconscious,

so this is crucial for me.

I also need this. This is a bit before its time.

It's a bite-proof shark suit and sharks haven't evolved yet,

but I'm hoping this will protect me from those vicious sea scorpions.

The bigger predators would be in deep water,

so I ventured out into the middle of the bay.

Doesn't look very appetizing,

but for the predators around here, this should be a tasty snack.

And I'm hoping that camera is gonna catch the moment

when a monstrous predator tries to snaffle this up.

There's something - something approaching.

It's a sea scorpion. They obviously like Trilobites.

Let go!

It was late afternoon before I got a decent bite.

There's something interesting there, and it is much bigger than a sea scorpion.

It's taken the camera. That's the end of the Trilobite cam.

I have got to see what that is.

I don't know what's happened here,

but if I follow the line I should be able to find the predator.

The camera's not at the end, which means the predator isn't far away.

This is intriguing.

I don't know what's going on. why they're all gathering.

But first there was one sea scorpion, then another, then another, then another.

Now they are all around me, a carpet of them moving along the sea floor.

They're whizzing past my head, they're all heading in one direction.

And there it is. It's an Orthocone!

That is the biggest predator that the world has seen up until this time.

He's sensed me here.

Hear my heart hammering.

I don't want to be grabbed by those tentacles,

but those simple eyes, they should shun the light.

So all I can do is start flashing my light,

and maybe that will discourage him.

And now he's gone. I can't...see where he is.

There's still the sea scorpions there.

Ah!

There's the Orthocone, and it's spotted one of the sea scorpions.

They're dragged to the mouth, where there's a beak.

I can actually hear it under the water,

hear the crunching as the sea scorpions are crushed by the beak.

These Orthocones probably spend a lot of time in deep water.

Light doesn't penetrate well down there,

so the eyes don't work well and they rely on another sense.

They will actually smell out their prey and then crush them to bits.

The Orthocone, that really is the top predator of Ordovician times.

It's not swimming very fast.

I can catch up.

Oh, yes!

Right up to the tip of the shell, it's a wonderful texture.

I am hitching a ride on the back of an Orthocone.

Hey!

As it got gloomier, I realized the Orthocone was dragging me deeper.

Time to get off.

Thanks, Orthocone, thanks for the ride.

Ah!

Argh!

This is what they were doing.

I saw them in the shallows, moving to the shore.

This is a mass spawning.

It's a full moon at the moment, this is the highest tide.

They're laying their eggs in the sand,

and when the next high tide comes, in a month,

the young larvae will hatch and be taken back out to sea.

Some of these sea scorpions are gonna stay here until the eggs hatch.

Fossils have been found with baby sea scorpions in the stomachs of big ones.

They wait here and feed on the babies as they hatch on the next high tide.

The Ordovician, then, isn't exactly a picnic.

Anywhere the air gives you a headache and you can't swim without chain mail

probably isn't going to take off as a holiday destinationI

But prehistory has worse still to offer.

The next deadly sea is the Triassic.

To get there, Nigel has to travel halfway back to the 21st century,

to 230 million years BC.

It's a time when reptiles are taking over the oceans

and the first dinosaurs are only just appearing.

(SCREECHES)

The Triassic is a crucial time for marine life.

Something new's happened.

The fish or mammals are not the most ferocious animals out there.

This sea is dominated by a group that used to just live on the land - reptiles.

Reptiles dominate everywhere right now.

Winged reptiles, the Pterosaurs, rule the skies.

And the future lords of the land, the dinosaurs, have just evolved.

But they're not much to look at yet.

Of course, I was here to explore life in the sea,

home to the largest Triassic reptiles of them all.

(HOWLING)

Fortunately, sea reptiles are easy to spot,

because they have to come up for air.

My first sighting was a Nothosaur.

The Nothosaurs could be nippy.

but there's bigger reptiles that could kill a person.

This is my insurance, an electric prod. If they come close, it should deter them.

There's not just one Nothosaur, there's a pair of them.

They're inquisitive, coming closer and closer, they're so curious.

I'm the first human that they've seen.

You don't know how they're gonna react.

I'm glad I've got this electric prod in case they become just too inquisitive.

But at the moment they're just curious, circling around me.

They've got a mouthful of teeth like razors - interlocking.

They seem to be the perfect fish trap,

and they certainly move fast enough to catch the fish that are around here.

Ha hah! Wow!

There's one coming close. I'm gonna try something.

Like with alligators, there is only one safe way to hold a Nothosaur,

and that's round the jaws.

Wa-hey!

A prehistoric ride with a Nothosaur.

They can close those jaws with tremendous force,

but the muscles that open them are really weak.

But Nothosaurs, like all sea reptiles, have to go up to the surface to breath.

I can't hold him for too long.

I'm gonna let him go now.

Go on, boy, off you go.

Hiding here, this isn't dangerous,

but it's surely one of the most preposterous reptiles ever.

Tanystropheus.

Great long neck, great long tail, there's hardly any body at all.

That long neck is perfect for an ambush predator.

What it probably does is sweep that neck through the water,

sweep it through a shoal of fish.

Ah!

(BAYING)

Dropped its tail.

Like when I was a little kid catching lizards.

They do this as well, and this is an insurance policy.

If they're attacked,

the predator's distracted by the tail and the creature can escape.

He'll grow the tail again and it shouldn't do him much harm.

He's swimming perfectly.

Golly, this tail, it's spasming so much.

I can hardly hold onto it.

Wow! Where did that come from?

I think it's a Cymbospondylus.

One of that great group of marine reptiles, the Ichthyosaurs.

He's a primitive member of the group.

They'll evolve into a whole variety of forms.

They'll be around for about another hundred million years.

But he's coming a bit too close.

And that slow movement, that's deceiving.

With one lash of that tail, they can have really great bursts of speed.

My heart's hammering. That lunge was a warning shot.

That's really upped the ante on this dive.

I need the electric prod now.

And he's coming again!

He's coming in again, and I'm gonna use it.

What a spectacular reptile!

Two seas down, five to go.

The next encounter takes Nigel back deeper into the past,

to meet the armored fish of the Devonian,

predators that are quite literally as hard as nails.

I use the time map to get my head round where I've been.

These spans of time are immense.

My first adventure, I went all the way back in time 450 million years ago,

to ride an Orthocone and tussle with sea scorpions.

My second dive was 230 million years before the present day.

That was with those bizarre sea reptiles.

We're now here, 360 million years ago.

Welcome to the age of giant armored fish.

Unbelievable!

- How was the dive, Mike? - Oh, outstanding.

It came so close!

I'll get this in the machine.

Mike did a reconnaissance dive, just to see what was around.

From what he says, we've struck gold on the first dive.

Exactly what we came here for.

Ah, look at that. That's it. Can't be anything else. A Dunkleosteus.

Well done, Mike!

- What was it like? That's a Leviathan. - My heart was in my mouth.

- It just took my breath away. - That thing is over 30 feet long.

Four or five tonnes, as much as two or three elephants.

Let's pause it, have a look at this.

What a fearsome head! This shows the classic features of Dunkleosteus.

Armor plating on the front of the body, up to two inches thick.

Those aren't teeth. Those are extensions of the jaw bones.

They're for shearing through prey. It has to punch through other armored fish.

Those jaws are backed up by powerful muscles at the back of the neck there.

And this is exciting, it's gonna be my turn next.

We're gonna find out how powerful those jaws actually are.

Our plan was to hand-feed a Dunkleosteus and my job was to get the bait.

Meanwhile, the crew was building a cage for my protection.

But why was it round?

In the same way that a dog can't bite a beach ball,

we hoped the jaws of the Dunkleosteus would slide off these bars.

This could be good. It's a big tug.

Fortunately, there's plenty of life in the sea in the Devonian.

On land, there are no creatures bigger than a centipede.

This is a placoderm.

It's Greek for ''armor plating''. You can see why.

This is in the same family as Dunkleosteus,

and for a naturalist, this is a privilege.

These fish were only around for 50 million years.

There's nothing like this around in the 21st century.

I've a bet on with the crew that the Dunkleosteus will slice through the bait,

if it's actually wrapped in chain mail.

This is where you feel at your most vulnerable,

swimming into the cage with a great chunk of bait.

I'm in now.

It will take a few minutes for the trail of the smell to bring in the predators.

And fingers crossed, we'll be able to see Dunkleosteus.

Look what's arrived.

This must be the most preposterous shark ever.

Look at that fin on the back.

Scientists call it the ironing board shark, and you can see why.

Must be a male; only the males had that bizarre dorsal fin.

Probably to help mating, probably to display to females,

maybe used in courtship battles between males.

And these are some of the first sharks ever to evolve.

And this is great for me, I am such a shark fan.

But that is surreal.

He's been spooked by something.

Here's a Dunkleosteus.

He must have smelled the bait. This is what we came for.

And it's coming straight towards us.

See that really thick protective armor on the head there, over two inches thick.

The first third of the body is covered with that.

These fish have got these massive jaws with big sharp shears sticking out.

They slice them together, just like scissors working.

The action of slicing them together keeps them sharp,

and with that they can cut through anything.

Let's see if I can win my bet.

Come on!

This is no fisherman's tale.

This is a real monster.

This is getting a little scary now.

This is getting serious. He really ran at the cage then.

He's coming again and he's fast!