Original subtitles

[narrator] Deep below the ocean 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...

[Gavin] What is that?

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

This is truly nightmare fuel.

Super predators with terrifying adaptations.

[Ron] Structures off their head that look 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...

-I have something! -What you got?

...will scour the darkest depths...

This thing is a monster. It's huge.

...digging for evidence in the unlikeliest places...

That's from a 50-foot shark.

Things really are bigger in Texas.

...to resurrect the strangest, biggest...

Oh!

...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.

[Austin] 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 could look 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.

[Ron] 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 have

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.

[Austin] Oh, we got a shark.

The team has pulled up a four-foot shark,

a survivor of the ancient past.

[Austin] Really cool.

Kitefin sharks are a deepwater 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.

Many of the prehistoric sharks that we see today show

a very elongated, almost snake-like body.

And as sharks continue to evolve, the tail started to

change, and it started to make more of a shape of

the classic fin that we see today.

The kitefin shark is a perfect example of an ancient shark

that is in the middle of evolution.

It's in the middle of this change.

Wow, look at the teeth. They're really sharp, yeah.

So definitely capable of biting and taking big chunks of flesh

out of species.

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 seafloor,

while hunting, as a way to blend

into the ocean from below.

[Austin] 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.

[twangy music plays]

[Kesley] 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? -I'm well!

[Kesley] 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.

[Ron] Welcome to the Texas Permian.

What we call Texas today, and pretty much all of 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 have once been

an ancient seafloor that 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 them.

Over the past few years, fossilized teeth from over

20 different ancient shark species have been discovered

in central Texas.

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.

[Kesley] Using these fossilized teeth, I'm here 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.

You're talking about sharks that would be larger than the truck that

you drove in here on. -[Kesley] 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.

[Kesley] No one thought sharks were that large that long ago.

[Ron] That's roughly a 300-million-year-old fossil, there.

-[Kesley] Oh, my gosh. -[Ron] Teeth are very distinctive.

Early shark teeth usually had multiple cusps.

Each one would have 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 mouth full 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, [indistinct], I'm gonna just 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 seafloor,

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.

[Austin] 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 hotspot for shark activity.

It's wildly unexplored, but teeming with life.

OK, good, good, good, good, good -- nice, easy.

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

OK, do it.

One, two, three.

-All right. -[clapping]

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, not seeing much right now, but it does

seem like we have good connectivity.

OK, OK.

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 100 million years.

Dogfish are preyed on by larger sharks,

so seeing one on the camera this early

is a really good sign.

The seafloor here is just loaded with life.

I'm starting to get, you know, 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 --

it's huge here -- it's a huge fish.

Whoa, this is crazy. Yuuki, come check this out.

I need your help.

I've got something big on the camera.

Holy.

[Yuuki & Austin] Wow.

[Austin] Yuuki, I've got something big on the camera.

In Suruga Bay, Dr. Austin Gallagher is

scanning the seafloor in search of any evidence

of the ancient sharks that still patrol these waters.

[Austin] 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

10 feet long with large blue eyes

that allow it to hunt at depth in low light.

[both] Wow.

That's awesome.

Yeah.

They know it's a predator.

But its most striking feature is its heavily ossified

reinforced skull, making it almost impenetrable.

Wow. It looks very ancient.

It almost looks like... like a dinosaur.

Yeah.

[Austin] 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 that are 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, shearing, 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.

-[Ron] Hey, Chris, how's it going? -Hey, guys.

-[Kesley] How are you? -How are you?

Good to have you guys.

Glad you could come see our bone bed.

-Thanks for having us, yeah. -Absolutely.

-It's amazing. -So, 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 salt water, 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... -[crunching]

...a lot.

-[Ron] Look at the barbs on that thing. -[indistinct]

So, for this species, this head spine would get up to

about 12 inches.

And I'm sure if you look around, you're going to start

seeing more and more of these things all over the place.

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

And we're gonna walk up the hill here.

[Kesley] All right.

[Chris] We're gonna look at the dead shark zone

because that's where the sharks are gonna be getting

bigger and bigger.

[Kesley] 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.

[Ron] 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.

-[Kesley] Hey, Ron, Chris! -[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.

-[Chris] That's a big tooth. -[Ron] That is a big whopping tooth.

[Chris] Wow!

[Kesley] So it's definitely a shark tooth.

-[Ron] That is a huge shark. -[Kesley] Like, how big are we talking?

[Chris] That's a monster tooth.

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

That looks like distant relatives in a modern-day

great white. -[Kesley] Oh, my gosh!

80- to 90-million-year-old Cretoxyrhina.

-A Ginsu shark. -[Kesley] 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...

[crunching]

...who clashed for prey with the Ginsu.

We actually do have specimens of Mosasaurs with

bite marks on them left behind by Cretoxyrhina.

It's 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 predominantly

hunted in the shallow coast.

[lifeguard whistle trills]

[crowd shouting]

[whistle continues trilling]

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

[whistle trilling]

...devouring them in a single bite.

[crowd shouting]

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.

[Dean] We've got just rows of these saw blades, and they actually

carve out chunks of flesh.

It's like seeing a dinosaur, because they swam around at

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.

Let's go.

[Dean] Most people, when we told them we were gonna

try to tag a shark from a submarine,

they thought we were completely nuts.

[indistinct radio chatter]

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.

[indistinct radio chatter]

Roger that.

With Dr. Gavin Naylor at the helm,

the crew is heading into the depths.

-[equipment buzzing] -[indistinct radio chatter]

[Gavin] Oh, this is pretty magical.

Control, on bottom, 524 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? -[Gavin] I think that looks perfect.

[crew] All right.

-Lights out? -Yep.

Now in position, the team turns off the lights,

trying to remain hidden from the prehistoric predators that

patrol the ledge.

[Gavin] So it'd be pretty funny if we get a sixgill

and it pushes us off the cliff.

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

[crew] Oh, here we go. Shark, go.

-[Gavin] Oh, and there's a grouper. -Oh.

[crew] Should I try turning on some other lights?

-[Gavin] Yeah, yeah. -[crew] 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.

[laughing]

-Oh. -[Gavin] What was that?

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

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

-We should be able to -- OK. -[indistinct]

-[indistinct] -- wow. -OK.

-Oh, here's the sixgill. -Whoa.

-OK. OK. OK. -Whoa!

[Gavin speaks indistinctly]

OK. [bleep].

This thing is a monster.

Oh!

[Gavin] That looks like a steep cliff.

Almost 2,000 feet beneath the ocean surface, a team of

scientists is attempting a world's first.

OK. Oh.

Tagging a sixgill shark from a submarine.

-[Gavin] Oh, here's the sixgill. -Whoa.

-OK. OK, OK. -Whoa!

-[crew] Want some white light? -[Gavin] Yes, white light now.

[bleep]!

-Oh! -Wow!

-[crew] Wow, look at that. -[Gavin] I'm not gonna shoot yet.

Shall I -- no, no, no. No, it's a gill.

It's a gill shot.

Belly shot. Look at the size of that thing!

-Oh-ho-ho-ho! -Wow.

-Gosh. -[Gavin] 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.

Whoa.

Feeding on just about anything it comes across.

-Whoa! -Oh, my goodness.

-[laughing] -[Gavin] It doesn't have any claspers at the base.

It's a female!

She's coming back at us.

She's interested in the sub.

Oh.

-Bumping the sub. -[crew] Whoa.

[Gavin] Look at the eye!

-[indistinct] -[Gavin] She's pushing the sub.

[crew] Where did she go?

Oh, look, there she is, there she is.

-[crew] Whoa. -[thwack]

-[Gavin] She's pushing the sub. -[crew] 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 the sub!

Whoa.

Oh, look, look, look, look.

Oh my goodness.

[indistinct]

This is not the same one.

[crew] I think that light might be scaring it away.

-Turn it off? -[Gavin] Yeah, yeah.

-[crew] OK. -[Gavin] Are we armed?

-[crew] We're still armed. You are armed. -[Gavin] OK, great -- OK.

A second, smaller sixgill is slowly approaching the sub.

[Gavin] I'm not gonna take a shot until I'm absolutely sure.

-Let me get some light on. -[crew] Lasers.

-[Gavin] OK, perfect. -[crew] Down light first.

[Gavin] OK, nice.

[crew] Do you want the main lights?

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

It's good.

[crew] Whoa.

[Gavin] OK, not yet, not yet.

That's OK, I'll do that.

This is male.

Come on.

OK...

Ooh!

[water thrashing]

[crew] You got it!

Damn.

Damn is just right.

[laughing]

Good call.

Tag went into a large male.

[cheering]

[Gavin] He's obviously got the hell out of here, because that was not

what he was expecting.

[crew] Nice job not hesitating there, Gavin.

-Thanks. -That was a nice shot, yeah.

[Austin] 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 them.

[Gavin] Look at the size of that thing!

[Austin] 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.

-Ready? -[Austin] 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.

[both] 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.

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.

The second drop is gonna be an area where particles

and dead organic material 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.

Yeah. Yes.

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

-All right, go, go. -Good, good.

[together] One, two, three.

Ooh.

[Austin] All right, guys. Good job, everybody.

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

All right, 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.

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.

But there's still more to uncover in

the mysterious abyss, as a large shadow

emerges from the depths.

Oh, what's that? That's huge!

That's really big!

[thwack]

[both] Oh!

Oh, my God! Wow, that is insane!

[both] Wow!

[Austin] Oh, this is crazy.

Whoa!

Oh, what's that? That's huge.

That's really big.

-[thwack] -[both] Oh!

While conducting research 3,000 feet deep in Suruga Bay,

Austin and Yuuki have come across a giant shark that's

fascinated by their camera.

Look at that mouth. That's awesome.

Yeah.

[Austin] Yeah.

Yep, Pacific sleeper shark.

Huge, monster 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.

-[Yuuki] Some shark? -[Austin] 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.

[Austin] So the feed is still running.

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

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? Come on.

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 going to 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 the 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.

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.

[Ron] Its lower jaw was a circular tooth whorl.

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.

[Austin] 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.

[snarling]

Two 25-foot apex predators.

The buzzsaw's tooth whorl 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.

[Kesley] 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 gonna find evidence of a Megalodon, it might just

be in these waters here.

[adventurous music plays]

[suspenseful tones play]

50 miles off the coast of Texas, Dr. Kesley Banks is

diving in a deep sea oil rig known as Jurassic Park...

...in search of evidence that the Megalodon swam here.

We found a Megalodon tooth.

Down beneath the rig, Kesley 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-sized 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 have

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.

[alarm blaring]

[suspenseful music playing]

-[alarm blaring] -Get to the bridge!

[thud]

[water roaring]

[alarm blaring]

[heavy cracking, rumbling]

[fire crackling]

[Austin] 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.

Might have something!

[Austin] With these missions, we are able to uncover

the apex predators of these ancient oceans.

We got a shark.

In Japan, we uncovered a living fossil.

[both] 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.

[squelching, snarling]

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 a 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 in here, right?

[Kesley] Oh, my gosh.

[Austin] Things you couldn't even 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.

[Gavin] Wow!

That's really big.

[Yuuki speaking]

-[thud] -[both] Oh!

It's amazing to think about how many other insane

prehistoric Jurassic sharks are still out there

yet to be discovered.