Original subtitles

- Deep below the ocean's surface... -OK, do it.

...lies the remnants of a forgotten past.

It's like going in a time machine. This is a marine biologist's dream.

- Before the age of dinosaurs... -What is that?

...the seas were ruled by monster prehistoric sharks.

This is truly nightmare fuel.

Super predators with terrifying adaptations.

Structures off their head that looked like anvils,

head spines, scissoring jaws.

These sharks were like nothing seen today.

Formidable predator that you did not want to get in front of.

Now teams of scientists from around the world...

-Might have something. -What you got?

...will scour the darkest depths...

This thing is a monster. It's huge.

...digging for evidence in unlikeliest places.

-That's from a 50-foot shark. -Things really are bigger in Texas.

To resurrect the strangest, biggest...

...and most fearsome...

...Jurassic sharks.

Sharks are among the oldest living marine species on the planet.

Sharks are older than trees themselves.

They've been ruling the oceans for hundreds of millions of years.

Before dinosaurs controlled the land and air,

the oceans were full of prehistoric predatorial nightmares.

We're talking about sharks that were larger than white sharks.

Massive hyper-predatory sharks with a lot of weird body styles.

But not all of these sharks survived for long.

Deadlier predators or mass extinctions

mean that these predators only reigned for a small era

before the next one came along.

In the shadow of Mount Fuji, Japan,

marine biologist Austin Gallagher is spearheading an expedition

to an ancient canyon thousands of feet below the surface.

Suruga Bay is the deepest bay in Japan

and it is the perfect location to study ancient sharks.

It's like going in a time machine.

Once an ancient marine battleground,

Suruga Bay is filled with bizarre creatures

and survivors of that forgotten era.

It's home to species like the frilled shark,

ghost shark and the goblin shark.

Species that used to swim alongside these Jurassic sharks.

These living fossil sharks are the last links

between the present and the past.

Living fossil is a species that exists today

that shows traits of a much more ancient early design.

Traits that were common millions of years ago.

Finding these living fossil sharks will help us better understand

what this ancient battleground looked like,

allowing us to bring these extinct Jurassic sharks

through animation like never before.

I think that this bay was home

to some of the most insane-looking super predators

that ever lived in the oceans,

like the scissor-tooth and the buzzsaw shark.

Two absolute killing machines,

the scissor-tooth and buzzsaw sharks were 25-foot monsters

with nightmarish jaw adaptations

that have baffled scientists for generations.

Nothing like that exists today.

Completely bizarre and unfamiliar to us in the modern world.

There's so little that's known about these prehistoric sharks.

So we're looking for living shark species

that would've swam alongside them

that can prove they were here and tell us more about them.

Austin is setting out with his research partner

and deep-sea expert Yuuki Watanabe.

-We've got a shark. -Kitefin shark!

The team has pulled up a four-foot shark,

a survivor of the ancient past.

Really cool.

Kitefin sharks are deep-water shark species

that have adapted to living at depth.

But I've never seen a live specimen up close.

So this is just an amazing shark.

Yeah, look at this tail.

It's elongated and it looks like a kite,

and this is why this shark is called kitefin shark.

Many of the prehistoric sharks that we see today

show a very elongated, almost snake-like body.

And as sharks continued to evolve and the tail started to change

and it started to make more of a shape

of a classic fin that we see today.

The kitefin shark is a perfect example of an ancient shark

that is in the middle of evolution, in the middle of this change.

-Look at the teeth. Really sharp. -Yeah. Those teeth are sharp.

So definitely capable of biting

and taking big chunks of flesh out of species.

I'm always interested by the eyes of this shark.

Green, big and like a jewel.

Adaptations are key

for the long-term survival of any species.

Their eyes has a different ratio of rods and cones

that gives them the advantage of seeing in pitch black.

The kitefin's eyes aren't their only deep-sea adaptation.

It is also the largest known shark to exhibit bioluminescence,

which researchers believe it uses

to see on the sea floor while hunting

as a way to blend into the ocean from below.

All right, let's get it back in the water.

As we explore deeper waters,

I'm really hoping we see sharks with even stranger adaptations,

which will teach us so much more about these Jurassic sharks

and help us bring them back to life.

Halfway around the world,

marine biologist Kesley Banks

is searching for extinct super predators

in an unexpected location.

We're in the middle of Texas, about 600 miles from the Gulf.

When people think of Central Texas, this is what they think about.

But what they don't think about

is this was actually the bottom of the ocean at one point.

The land now known as Texas has dramatically changed

over hundreds of millions of years.

Once the Western Interior Seaway,

a body of water that divided the continental US,

Texas has seen multiple eras of oceanic super predators,

some of which left evidence of their existence.

-Hey, Ron. How are you? -Hey, how are you doing? I'm well.

I'm here to meet with my friend Ron. He's a paleontologist.

So if anyone has the answer to what ruled the prehistoric sea, it's him.

Welcome to the Texas perineum.

What we call Texas today,

and pretty much all over the Earth's land masses,

have been slowly shifting around

ever since they first formed over four billion years ago.

All of this sedimentary rock here

would've once been an ancient sea floor.

It was teeming with prehistoric life.

This land is brimming with reminders of the ocean that once was

and all of the amazing creatures that lived in it.

So the water's gone, but the sharks are still here.

The sharks are still here. If you know where to look for 'em.

Over the past few years,

fossilized teeth from over 20 different ancient shark species

have been discovered in Central Texas.

These seem, morphologically, like modern-day sharks.

This one kind of looks like a...

-a very large mako tooth. -I'll take your word for it.

I've not encountered a mako shark before, but I'm sure you have.

I have. Like, I would... If you were to put this in my hand,

in size, you know, that's very similar to a mako tooth.

-Does it actually look like that? -They do. They're very pointed.

That's not a mako, but this one is around...

80 to 90 million years in age.

-And it's from Central Texas. -That's impressive.

We've had a selection of things. Turns out there were a lot.

There's quite a bit of diversity, different kinds of fossil sharks

preserved in these rocks in Texas.

We find them throughout the rocks across this region.

What's neat is all these rocks, they still preserve these remains.

You can go out and dig them up today and find a remarkable diversity.

For instance, we'll even find

some of these rarely preserved bones of the skull.

Unlike a lot of other sharks, they actually mineralized

some of the bones of their skulls and jaws.

Usually shark skeletons are terribly preserved.

You don't usually find them.

-And this is the jaw? -That is a left lower jaw.

-A left lower jaw. -Actually flip it.

There we go.

That's the jaw joint in the back.

-Oh, cool. -Yeah. So there you go.

-Exactly. -Perfect.

One of these fossil sharks...

A lot of these specimens are anywhere from 300 million

to, say, 270 million years in age.

This was a golden age of sharks.

This was a time when sharks

reached their maximum diversity and abundance.

They started adapting to all sorts of different opportunities

and evolving different body structures, new kinds of teeth,

new kinds of swimming, new kinds of tails.

And the most successful designs make it through

and the rest would go extinct.

Using these fossilized teeth,

I'm trying to find the largest and the baddest shark

that ruled the waters of Texas 300 million years ago.

At its time, the largest predatory animal on the planet

would be the Texas super shark.

We're talking about sharks that would be larger

-than the truck you drove in here on. -Oh, my gosh.

Reaching up to 30 feet long,

the Texas super shark was larger than modern-day white sharks.

It was a savage killing machine

that ruled the oceans 300 million years ago.

Discovered in 2015,

it dramatically changed our understanding

of ancient predators of the area.

No-one thought sharks were that large that long ago.

That's roughly a 300-million-year-old fossil.

-Oh, my gosh. -Teeth are very distinctive.

Early shark teeth usually had multiple cusps.

Each one would've been a batch of points

to slam down on and hold slippery prey.

Even with defense mechanisms,

smaller sharks were no match for the super shark.

That thing had a mouthful of needles.

Great for piercing prey, holding it, ripping it to shreds back in the day.

With its four dorsal fins and streamlined body,

the Texas super shark could easily outmaneuver smaller sharks

in the shallows.

And with a set of massive jaws,

it could cut through its prey in a single bite.

The Texas super shark is believed

to have battled the scissor-tooth for prey during its reign,

controlling the shallow feeding grounds.

Predators like the scissor-tooth would have used deeper waters

to avoid large predators like the Texas super shark,

thriving in deep sea canyons like Suruga Bay.

All right, Shigeto, I'm going to turn it on.

-So this will be A. -A.

Austin is preparing to explore the bay

with a deep-sea camera system.

This is a pressurized housing

that allows the camera inside to be protected

while we film at depth.

The amazing thing about Suruga Bay

is that a lot of what's down there is a mystery.

We could really see anything.

This setup is completely untethered,

so when we put it over the side of the boat, that's it.

It will sink to the bottom of the sea floor

and it allows us to access areas that otherwise we wouldn't be able to

and that's gonna be huge for this investigation.

The team is targeting an area in the bay over 2,000 feet deep,

dead center in what researchers call the twilight zone.

And it's good to go.

Twilight zone is a part of the ocean that goes from 600 to 3,000 feet deep

that is completely dark.

This is the zone at which light disappears

and it's also the area that is a hot spot for shark activity.

It's wildly unexplored, but teeming with life.

OK, good, good, good. Nice, Yuuki.

I'm ready to get this camera wet. Let's go.

OK, do it. Two. Three.

All right. All right. Let's go, let's go.

All right, so, we've got the live feed in the water.

I'm really excited to see.

Despite its depth, the camera is able to wirelessly connect

to the monitor on the boat,

giving Austin a front row view of the ocean floor.

All right.

Now almost half a mile deep,

Austin is looking for any indications

of the bay's ancient sea life.

It's pitch black. I'm not seeing much right now.

But it does seem like we have good connectivity.

OK, OK. We've got something coming in here.

That looks like some sort of dogfish. Beautiful specimen.

Dogfish are a relatively smaller group of sharks

that have been around for about a hundred million years.

Dogfish are preyed on by larger sharks.

So seeing one on the camera this early is a really good sign.

Wow.

So, this is amazing.

This is the largest crustacean on planet Earth.

The Japanese spider crab.

This one's huge.

It's actually known to be almost ten feet long

in total arm length when it's kind of spread out.

These are huge. They move a lot over the sea floor.

Kind of like the isopods, scavenging for what prey items

and dead things are kind of on the bottom there.

One of Suruga Bay's most famous deep-sea dwellers,

the Japanese spider crab is known for its massive size.

With its incredibly long legs,

it can reach up to ten feet in length.

Look at those claws.

So, to get that big you have to have a lot of food.

So there's clearly a food source down there

for bigger predators.

The sea floor here is just loaded with life.

I'm starting to get a little bit of an understanding here.

There seems like there's a decent prey base

down at the bottom here, which is really great.

Oh, what's this?

I think we have something huge here.

This is a huge fish.

Whoa, this is crazy.

Yuuki, we've got something big on the camera.

In Suruga Bay,

Dr Austin Gallagher is scanning the sea floor

in search of any evidence of the ancient sharks

that still patrol these waters.

Wow. That's a Yokozuna slickhead.

The Yokozuna slickhead has probably been around for millions of years,

but only discovered a few years ago.

It is so wild to me that we're still discovering

all these large predators today.

Named for the highest rank

a Japanese sumo wrestler can achieve,

the Yokozuna slickhead is ten feet long with large blue eyes

that allow it to hunt at depth in low light.

-Wow. -Wow.

Oh, my. That's awesome.

-They scare the other fish away. -They know it's a predator.

But its most striking feature

is its heavily ossified reinforced skull,

making it almost impenetrable.

It looks very ancient. It almost looks like...

-like a dinosaur. -Yeah.

Looking at the body plan of this species, it is ancient

and it reminds me of prehistoric monster fish.

The beast is similar to the ocean's first apex predator,

swimming 400 million years ago.

The Dunkleosteus, also known as the Dunk,

was the stuff of nightmares.

It was the top predator. These things were 30 feet in length,

notable for having armor plates over the head and parts of the body.

Besides its armored head, the Dunk had sharp plates for teeth

that could easily crunch through bone.

Instead of true teeth,

their jaws actually formed large sheering scissoring blades

to slice and dice their prey.

Everything was on the menu.

Doing this type of research when Dunkleosteus was in the water

would have been a very different situation.

Fishermen certainly would have had a different experience.

If alive today,

the Dunk's teeth would easily be able to snap through metal.

And with its immense size and strength,

it would have the power to take down ships.

After the Dunk's extinction,

the Texas super shark became the ocean's top predator.

And once this behemoth went extinct,

its disappearance allowed

for a new breed of super sharks to evolve.

Back in Texas, marine biologist Kesley Banks

and paleontologist Ron Tykoski are searching the dig site

for remains of another prehistoric predator

that could have been even more ferocious.

-Hey, Chris. How's it going? -Hey, guys.

-How are you? -How are you?

Good to have you. Glad you could come see our bone dig.

-Yeah. -Absolutely. Amazing.

You guys are standing in one of the best bone beds in the entire world.

We've got a site that's full of sharks.

This fossil bed may hold tooth remains of a predator

that rose to dominance after the Texas super shark.

One of the most exciting things about this fossil bed

is the ecosystem is so well preserved

that we actually do see lots of bits and pieces of sharks.

And so we see things like the Orthacanthus teeth,

and the head spines, so the venomous spines.

A small eel-like shark,

the Orthacanthus swam through both fresh and saltwater,

feeding on crustaceans with its barbed teeth

while using its poisonous head spine to fend off predators.

If you were a bigger shark and you came and bit down on this one's head,

you got a spine in the roof of the mouth that probably hurt a lot.

Look at the barbs on that thing.

So, for this species, this head spine would get up to about 12 inches.

I'm sure if you look around

you'll start seeing more and more of these things.

So, here's some brushes for you guys and a pick

-and we're going to walk up the hill. -All right.

We're going to look at this dead shark zone

because that's where the sharks are gonna be getting bigger and bigger.

This area is home to so many ancient shark species.

I'm hoping to find evidence of these giant super predators

to find out who really ruled the prehistoric seas.

This is how high-tech fossil prospecting is.

You keep your eye to the ground. Nothing terribly high-tech.

Looking for bits and pieces of bone

and things that are eroding out, like that.

And you just keep your eyes open

for things that Mother Nature has already exposed.

Right now we're just looking to see if something has started

to kind of poke through this top layer of sediment.

Hey, Ron, Chris.

-Yep? -Might have something.

What you got?

I'm not sure.

But it doesn't look like the rocks that are around it.

Something's eroding out there. Start digging it up.

-That's a big tooth. -That is a big whopping tooth.

Wow.

-So, it's definitely a shark tooth. -That is a huge shark tooth.

-How big are we talking? -That's a monster tooth.

That's from a 30 to 50-foot shark.

That looks like distant relatives

-of a modern-day great white. -Oh, my gosh.

80 to 90-million-year-old Cretoxyrhina.

-The Ginsu shark. -That's awesome.

100 million years ago,

the Ginsu shark, nicknamed for its knife-like teeth,

was one of the most formidable predators to ever swim the oceans.

Cretoxyrhina lived in the age of big marine lizards called mosasaurs.

The mosasaur, a prehistoric reptile with the body of a crocodile,

clashed for prey with the Ginsu.

We actually do have specimens of mosasaurs with bite marks on them

left behind by Cretoxyrhina.

Absolutely incredible to find an 80 to 90-million-year-old shark

this far away from the ocean.

If this shark was alive today, it would decimate the Gulf Coast.

Imagine something that big hunting in shallow water.

Although it was enormous,

the Ginsu predominately hunted in the shallow coast.

Using both its size and speed, it preyed on smaller sharks...

...devouring them in a single bite.

As the seaway over Texas shrank,

the Ginsu struggled to survive in a new environment.

But one of its prey, the sixgill shark,

survived by taking refuge deep in the newly formed Caribbean Sea.

-Safety check. -Safety check.

Recently, a team of marine biologists

launched an investigation there

in a 2,000-foot abyss dubbed the Tongue of the Ocean.

The favorite hunting ground of these living fossils.

The sixgill sharks are huge predators in the deep ocean,

getting sizes up to 14, 15 feet long.

Got just rows of these saw blades.

They actually carve out chunks of flesh.

It's like seeing a dinosaur 'cause they swam around the same time

and they haven't changed much in a few hundred million years.

There's so little that's known about these prehistoric sharks

because they live so deep in the ocean.

-Here we go. -Most people, when we told them

we were gonna try to tag a shark from a submarine,

-thought we were completely nuts. - Good to launch.

No one has ever tagged a sixgill or any other shark at this depth.

Doing so could dramatically change shark research

and allow scientists to see how these prehistoric predators thrived

and staved off extinction through migration.

- Good to launch. -Roger that.

With Dr Gavin Naylor at the helm, the crew is heading into the depths.

I can see it.

It looks like a little crinoid.

I am really excited.

I'm a little bit apprehensive

because I realize that I'm going down to depth

to see a 16-foot mysterious animal.

Between 200 and 1,000 meters deep or so,

the dominant large predatory shark is a bluntnose sixgill shark.

They're enormous. Their jaws open really wide.

Their teeth are huge saws, basically.

They're a pretty formidable predator in their environment.

Control, control, we're at one-zero-zero meters, descending on.

Wow, this is pretty magical.

Control on bottom, five-two-four meters.

That looks like a steep cliff, like a ridge.

It is a ridge.

1,700 feet beneath the surface,

they reach the edge of an ancient abyss.

-How about here? -I think that looks perfect.

-All right. Lights out? -Yeah.

Now in position,

the team turns off the lights, trying to remain hidden

from the prehistoric predators that patrol the ledge.

So, it'd be pretty funny if we get a sixgill

-and it pushes us off the cliff. -Right.

I think something's down here. What is that?

-Oh, here we go. Shark. -Here we go.

And there's a grouper.

Should I try turning on some other lights?

-Yeah, yeah. -Whoa, that's a big grouper.

Goliath groupers can weigh in at up to 800 pounds,

with a lineage that dates back millions of years.

Oh. Whoa, what was that?

-He's right here. -Oh, he's here?

He's right here. You should be able to see him.

-We should be able to see him. -OK.

-We are armed for gun one. -OK.

Oh, here we go. A sixgill. OK, OK, OK.

-Some white light? -Yes, white light now. OK.

----.

-Wow, look at that. -I'm not gonna shoot yet. Shall I...?

No, no. That's a gill. That's a gill shot.

No, no, he's... Belly shot. Look at the size of that thing.

-Oh, my God. -It's huge. This thing is a monster.

Reaching up to 18 feet in length and 1,300 pounds...

Wow!

...the sixgill is a massive voracious predator...

...feeding on just about anything it comes across.

Oh, my goodness.

Doesn't have any claspers at the base. It's a female!

She's coming back at us. She's interested in the sub.

Bumping the sub. Look at the eye.

-She's pushing the sub. -The whole sub.

Where did she go?

Oh, look. Here she is. Here she is.

She's pushing the whole sub.

She's gonna knock us off the damn cliff.

Look at it.

The head is three feet wide. That is an enormous animal.

Look at the width of that thing.

That's bigger than most white sharks.

It's bigger than this sub.

Oh, look, look, look, look, look.

Oh, my goodness. We've got a visitor.

This is not the same one.

I think that light might be scaring her away.

-You want me to turn it off? -Yeah, yeah, switch it off.

-OK. Are we armed? -Still armed.

-You are armed. -OK, great. OK.

A second, smaller sixgill is slowly approaching the sub.

I'm not going to take a shot until I'm absolutely sure.

-Can we get some lights on? -Lasers.

-OK. Perfect. -Dome light first.

OK, nice.

Do you want the main lights?

No, no. It's good. It's good. Yeah, it's good.

OK, not yet. Not yet.

Too close to the head. I can't do that.

This is... male. Come on.

OK.

You got him.

Aim is right.

Good draw.

Tag went into a large male.

Roger.

He's obviously got the hell out of here

'cause that was not what he was expecting.

Nice job not hesitating there, Gavin.

That's the money shot.

Being able to tag a sixgill shark at depth

is a really big achievement for science.

It gives us the chance to study them without disturbing.

Look at the size of that thing.

Tagging helps us understand

the behavior and the ecology of shark species.

Where they go, what depths they prefer,

and what their migrations look like during the year.

This gives us insights into how prehistoric sharks

may have survived while others did not.

While the sixgills' migration away from the ancient Texas sea

helped it survive,

the surviving prehistoric sharks of Suruga Bay

relied on the deep sea trenches to stave off extinction.

I believe that here in Suruga Bay

there are more prehistoric sharks to uncover

that can teach us about apex predators that once lived here.

Austin and his team are searching for the living fossil sharks

that can help paint a picture of the extinct super predators

that once swam here.

Yeah, that's good.

First drop we learned a lot.

We had a great view of the Yokozuna slickhead,

one of the rarest and oldest fish in the bay.

-Wow. -Wow.

Now we're going deeper to try and find

some of the bay's weirdest and craziest sharks.

Sharks that were prey to some of the biggest Jurassic sharks.

Just like the scissor-tooth and the buzzsaw shark,

two of the wildest and deadliest sharks to ever live,

both of which Austin believes prowled Suruga Bay.

If we can find evidence of these living fossils,

we know that they hunted in the area.

We are rigged up for this second location.

Yeah, this is nice construction.

Put a lot of bait on there. Ready to go explore this new environment.

We're gonna go a little bit deeper. Around 3,000 feet.

Second drop is going to be an area

where particles and dead organic materials sink

and that creates more habitat for consumers, scavengers,

and, of course, big sharks.

Layered with organic debris,

the deeper drop location is a deep-sea graveyard,

home to the remains of ancient sharks long extinct.

But the decomposed material creates a feeding ground

for some of the largest and strangest sharks in the area

that have survived.

I'm very excited.

-Hopefully we get big monster sharks. -Yes.

So, let's get this loaded and let's put it in.

Good. Good.

One, two, three.

All right, guys. Good job, everybody.

That was great. Thank you, guys. Thank you.

All right. The feed is still working.

That's good because we are considerably deeper here.

Perfect view of the sea floor here.

It's pitch black. Not seeing much right now.

Hold on a second. Is that what I think it is?

Wow. I've never seen one of these before.

This is a chimaera, also known as a ghost shark.

The ghost shark is actually the most ancient vertebrate

that exists today on the planet.

Living deep beneath the surface,

the ghost shark evolved 400 million years ago.

Nothing else like it exists in the waters today.

With more of a shark-like front but a tail resembling a fish's,

it provides a snapshot into prehistoric evolution.

It's really interesting because, also known as a chimaera,

which is sort of this hybrid, you know, amalgamation

of a lot of different species.

Ghost sharks are really rare, which is why they earn this name.

So to be able to see a ghost shark here in Suruga Bay

would prove that this area was an ancient battleground.

From Greek mythology, the chimaera is a monster

with a lion's head, goat's body, and a serpent's tail.

A patchwork creature just like the ghost shark.

If you look at its body, it's totally wild.

It has wings for pectoral fins and it can have a really long tail

and a transparent-like body.

And it's called a ghost shark because it almost disappears

from the fossil record.

To be able to see a ghost shark here, incredible.

One of the most ancient creatures to ever exist.

3,000 feet below us right now.

Somehow these animals have continued to persist.

It's just so cool.

When you see the ghost shark,

you wonder, how did this thing survive?

It's relatively small

and it can fit into a lot of different crevices

and canyons in the deep ocean and hide from larger predators.

But when that species emerges, you get this incredible view

of what life looked like hundreds of millions of years ago.

And it was swimming with some of the wildest Jurassic sharks.

Sharks like the scissor-tooth shark.

The scissor-tooth shark had a conveyor belt

with two rows of teeth that it would use to hunt prey at high speeds.

There's still more to uncover in the mysterious abyss,

as a large shadow emerges from the depths.

Oh, that's... What's that? That's huge. That's really big.

-It hit the camera. -Oh, my God.

Wow, that is insane.

-Wow. -Wow.

OK. This is crazy. Whoa.

-Look at that mouth. That's awesome. -It tried to eat camera system.

-Yeah. -It's a monster. Real monster.

-It's huge. -Yes.

-So, it must be a sleeper shark. -Yeah. Pacific sleeper shark.

They are really monster.

Huge monstrous shark.

Look at those teeth.

Sleeper sharks are unreal.

They are one of the largest predators in the deep ocean.

They are voracious predators

and they're known to eat pretty much anything.

Wow. It has this massive wound right on the belly.

-Some sharks? -Something really big.

That bite is huge.

Probably came from another shark. Maybe another sleeper.

You can see on the wound the shape of the jaw.

Another species clearly attempted to eat and kill this sleeper shark,

and it was unsuccessful.

This one clearly came out on top or just got away.

But Austin is still hoping to uncover

some of the strangest sharks of the bay.

So, the feed is still running.

I see the bait. It's a little bit murky.

OK, I see some shadows in the back.

OK, I see a big shape moving by.

OK, OK. We've got something coming in here.

What is this? It's long.

What is that?

Oh, my God. That's amazing. This is a frilled shark.

And that is as close to a Jurassic type shark

that we're gonna get.

A true alien shark of the deep.

The frilled shark has a six-foot-long eel-like body

and gets its name from its ruffled gill slits.

And because it lives so deep in the ocean,

it's very rarely seen by humans.

Seeing a frilled shark is a highlight of this expedition.

There's probably less than 100 people on the planet

that have seen a frilled shark, so this is a huge find.

Wow. And the mouth is just unbelievable.

The frilled shark has rows of trident-shaped teeth

not inside the mouth but on the outside of its jaw.

A trait it shares with the scissor-tooth

and its distant cousin the buzzsaw shark.

Perhaps the weirdest shark in the ocean, ever.

The buzzsaw had a bizarre jaw adaptation.

Its lower jaw was a circular tooth whirl.

So when it would open its jaws, it would bite something,

pull it into its mouth, and slice and dice it.

Talk about nightmare fuel.

But when facing off against the scissor-tooth,

only one could come out on top.

The buzzsaw shark and the scissor-tooth

were both swimming together

when evolution was trying to figure out

which adaptations would be needed to make a true super shark.

Two 25-foot apex predators.

The buzzsaw's tooth whirl could cause serious damage.

But it wouldn't come close to the two rows of teeth

the scissor-tooth used to eviscerate its prey.

So, this looks like an animal

that shouldn't exist on planet Earth today.

But here in the deep waters of Suruga Bay, we have them.

This proves that Suruga Bay was an ancient battleground

for these large Jurassic sharks,

dominated by the scissor-tooth.

But even the apex predators of Suruga Bay

would have been no match

for the largest super shark to ever live.

Back in Texas, Kesley is headed from land to the seas

to hunt for evidence of the megalodon.

Finding ancient sharks in the middle of Texas,

where there's no modern-day ocean, was so incredible.

But I've heard evidence of megalodon remains here in the Gulf.

And I'm here to see if they actually terrorized these waters.

The most famous monster prehistoric shark, the meg,

was a coastal predator who terrorized the Gulf

20 million years ago.

Bigger than a school bus,

its jaw span was wide enough to swallow a car whole.

And its bite force was unheard of.

Eight times stronger than a modern great white's,

making it a killing machine.

So, we're diving at this rig called Jurassic Park.

Dubbed Jurassic Park by local fishermen,

this abandoned rig is known to be a treasure trove of fossils.

That's because the oil beneath the ocean

is formed by the remains of ancient marine life.

So, this will be prime habitat to find these ancient shark teeth,

while also potentially encountering modern-day sharks.

Kesley will dive over 60 feet to the bottom of the rig

to search for evidence that megalodons swam here.

If I'm going to find evidence of a megalodon,

it might just be in these waters here.

This is topside. Kesley, how's your visibility?

Super murky.

Hard to see.

The rig is beautiful, though.

Definitely seeing a lot of prey.

But the water is pretty cloudy.

I'm gonna go deeper and hope it's calmer.

- Definitely clearer down here. - Copy that.

There is so much life down here.

I'm going to check out the sea floor.

Some of the things down here have been

here for hundreds of millions of years.

Let's see what fossils we can find.

I got something here!

Bringing it up to get a better look.

Copy that.

We found a megalodon tooth.

Down beneath the rig,

Kelsey uncovered what she believes to be the tip of a tooth

belonging to the largest shark known to man.

I could only have hoped to find a meg tooth.

The fact that I actually found one on this dive is incredible.

The megalodon had teeth that were seven inches long,

much larger than any of the other fossilized shark teeth

we've seen on this expedition.

You compare megalodon to the other super-size sharks,

there's no comparison.

There simply hasn't been anything bigger.

You're talking about a massive, big-toothed hyper-predatory shark

that can bite through a whale.

No comparison.

If the meg were around today,

working on this rig would've been even more dangerous than it is.

If megalodons swam in our oceans today,

engineering a rig to withstand it would have been a losing battle.

Even the strongest steel would be no match for its bite.

Get to the bridge!

Everyone knows about the meg,

but there were so many exciting species that existed before it.

There's so little that's known about these prehistoric sharks.

So it's up to us, as researchers, to try and piece those parts together.

I have something!

With these missions, we were able to uncover

the apex predators of these ancient oceans.

We've got a shark.

In Japan we uncovered a living fossil.

-Wow. -Wow.

Helped us better understand

the scissor-tooth shark fed on prey in these canyons.

We're here in Texas.

We saw how the Ginsu's teeth evolved to be super lethal.

There's hundreds of millions of years of shark history on the planet.

What is clear is, as time went on,

each geologic era had their super shark.

The first was the Texas super shark.

The Ginsu shark came next.

And with its sharp pointed teeth,

it was an even bigger killing machine.

But at the end of the day,

nothing compared to the size of the meg.

Megalodon was the true ruler of the Jurassic sharks.

Scientists are discovering new species all the time.

Sharks larger than the truck you drove here on.

-Oh, my gosh. -Things we couldn't imagine existed.

This is 3,000 feet below us.

And as technology continues to advance,

we're getting this incredible view of these ancient sea beds.

Wow!

-That's really big. -They are really monster.

It's amazing to think about

how many other insane prehistoric Jurassic sharks

are still out there, yet to be discovered.

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