Original subtitles

Narrator: A lost world of giants, 60 million years old.

Ruled by a slithery monarch of unbelievable size.

It sounds like fantasy, but it's not.

This world was once here.

Among these seams of coal lies the evidence.

Man: This is a once-in-a-lifetime discovery,

really, this is just amazing.

Narrator: A treasure trove of fossils.

One, a terrifying stealth killer,

straight from our darkest nightmares.

Man: You make a discovery

and you know that it's gonna be something

that everyone knows about.

Narrator: It's the biggest of its kind ever to live.

Man: We're absolutely ecstatic, we were giddy schoolboys.

Narrator: This mighty predator dominated then disappeared.

Now, science is bringing it back.

Man: Wow.

Narrator: This is Titanoboa.

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[Dinosaur roars]

[Explosion]

65 and a half million years ago,

a giant meteorite hits the earth near Mexico.

The rule of the dinosaur is over.

The next 10 million years is one of the most mysterious times

in earth's history,

and in one part, the South American tropics,

the mystery is total.

There is only silence,

until something remarkable happens.

This is Cerrejon.

A grand canyon carved by vast machines,

gouging out 35 million tons of coal every year.

A hole in the earth the size of 8,000 football fields.

But this mine is not just spitting out coal,

it's also an accidental time machine.

Every layer is a slice of earth's history.

In December 2002, a sharp-eyed Colombian geology student,

Fabiany Herrera, spotted something completely unexpected

at the mine...

A fossilized leaf.

It was the first tiny step in an unparalleled scientific quest.

Over the coming decade,

it would reveal a vanished world and a lost time.

Herrera showed the fossilized leaf to his mentor,

an expert in prehistoric plants.

Carlos Jaramillo: He brought the leaf back to the lab

and I realized the amazing opportunity

and potential that this mine had.

Narrator: Carlos Jaramillo eventually got permission

for a team of scientists to dig at Cerrejon.

The results were extraordinary.

The single leaf fossil was only the first clue to the lost world

that emerged after the dinosaurs.

They found the very first bean plants

and fossils showing an explosion of plant families,

like the banana,

the palm,

the avocado,

and even chocolate.

It all added up to a huge and stunning discovery.

Jaramillo: The coal itself is a chunk of rainforest

that is preserved back in time.

Fabiany Herrera: We believe that

this might represent

the birth of modern rainforest

in South America.

Narrator: 60 million years ago, this massive bowl of coal

contained the first recorded tropical rainforest.

This is the new living earth

that emerges after the meteorite destroys the old.

Amid the coal dust, it seems almost impossible to imagine it.

Jaramillo: Today it's a very dry place,

but 60 million years ago, this was a tropical rainforest

with tree birds meandering, big trees and mist.

Narrator: But this is much more

than a story of trees and leaves.

Jaramillo: We want to study the whole ecosystem,

the geology, the plants, and the animals.

Narrator: It is those animals

that will capture the world's imagination,

identified from an amazing variety of clues...

Ribs, shells, and vertebrae, or backbones.

It will need a specialist in animal fossils to decode them.

In 2004, Jon Bloch, an expert in fossil vertebrates

traveled from the university of Florida to Cerrejon

for the first time.

He was astonished.

A whole new ancient world of vertebrates,

animals with backbones that would dominate earth's future,

was opening up.

Jon Bloch: The most exciting observation was that

these were bones from the tropics of South America,

from that 10 million years

following the extinction of the dinosaurs.

And why that was so exciting is that we had no record whatsoever

of vertebrates on land during that time period.

We just had no idea what was here.

Narrator: Cerrejon was becoming a laboratory

for investigating the lost tropical world.

In 2005, Carlos Jaramillo joined

the Smithsonian tropical research institute.

It was able to guarantee this huge endeavor

the long-term backing it would now need.

Jaramillo: Every time we come here,

we are mesmerized with all the new things we found

that we never expected.

Narrator: Jon Bloch and his colleagues begin their search.

It is soon apparent that the lost world teems with animals.

Bloch: Initially, when we started collecting,

especially on this slope,

there was so much bone

that we picked up a lot of things all at once,

it was almost like a salvage kind of operation.

Narrator: It's also clear

that two creatures particularly thrive.

Bloch: This is a piece of a very large turtle here,

and then right next to it,

there's a backbone of a very large crocodile,

beautifully preserved.

Narrator: The sheer scale of the fossils is amazing.

Turtles with shells the size of pool tables,

snub nosed crocodiles as long as an SUV,

and species never seen before.

Bloch: We would pick up things very quickly, wrap them up,

so we could clean them back at the lab and then study them.

Narrator: The turtle and crocodile fossils

were temporarily loaned to the research team

by the Colombian geological survey.

Then, one night at the lab at the university of Florida,

something strange begins to happen.

Grad student Alex Hastings

is sorting yet another box of fossils from Cerrejon.

Alex Hastings: I received the fossils

and was just unpacking them late one night.

All of these were labeled "croc vert."

I get out several crocodile vertebrae.

A couple of vertebrae did not match,

they were very, very distinct, very large,

and I didn't know exactly what they were.

Other than that I knew

that they were definitely not of crocodiles.

Narrator: Another grad student, Jason Bourne,

a reptile specialist, is also working late that night.

Jason Bourne: So I was just coming back from class

and Alex was there,

and he just had a couple of things he wasn't sure about,

and so he said, do you have any ideas what this might be?

And I picked it up

and I just kind of stared at it for a second.

It was, you know, crushed pretty flat.

My eyes got really wide

and I was like, oh, this is a, you know, giant snake.

Hastings: Once we compared that to modern snakes,

it became incredibly clear

that they were definitely snake vertebrae,

and we were able to figure out

that we really had, not only a large snake,

but the largest snake that has been known to science.

Narrator: It hardly seems possible.

The vertebrae indicates a snake

vastly bigger than any snake today.

So big that it stretches the entire length of the lab.

Bourne: Probably this big.

Hastings: That's probably a bit smaller.

We were absolutely ecstatic, it was a very exciting moment,

and for that evening, we were the only people in the world

that knew about it at the time.

It wasn't until the next day

we started bringing in Jon and everybody else.

So for one evening, we're the only people that knew

we had this enormous, massive snake,

and we were very, very excited.

Narrator: Incredible though it is,

it seems two grad students have on their hands

one of the biggest discoveries of the century.

It's like finding t-Rex.

The next morning, a third person, Jon Bloch,

is let in on the secret.

Bourne: I just couldn't wait to get in the next day

and tell Jon what happened.

You know, I just remember saying,

"do you know you have the largest snake in the world?"

And his face just kind of dropped,

and, you know, he was just like, "are you kidding me?"

Bloch: I think, probably,

my reaction was pretty similar to the reaction

that maybe my seven-year-old son would have experienced.

And just complete excitement and awe

that such a huge snake exists.

Narrator: It is a sublime moment

that most scientists can only dream of.

For a few precious hours,

the two young students and their teacher hold a secret

that will open up a whole new chapter in natural history.

Bloch: During the course of your career,

you don't have a lot of moments where you make a discovery,

and you look at it, and you just sort of get that feeling,

you know that you're really not gonna be the only person

that knows about this thing,

that it's gonna be something that everyone knows about.

Narrator: The extraordinary night in the lab

will propel Jon Bloch into an age-old human obsession.

Snakes have always been symbols of threat and danger.

From the serpent in the garden of eden,

to the mythical dragon snakes gave rise to,

they are the beasts humans must fight or be destroyed by.

An animal that strikes awe and terror

into cultures from ancient China to the new world.

There are frighteningly good reasons for these fears.

Around a million people are bitten by venomous snakes

each year.

Up to 90,000 die.

Tens of millions are gripped by snake phobia.

The giant discovered in Cerrejon, though long extinct,

will add an unimaginable new dimension to snake lore.

But the single vertebra is only the start.

The team's investigation will take them away

from the long dead,

into the living world of large snakes.

From there, they will enter a time tunnel

and confront a creature unlike any other.

The scourge of the lost rainforests of South America.

A predator squeezing the life out of its victims.

The snake to beat all snakes.

Man: It tagged you good, look at that, Jesus.

Narrator: It was the fossils unearthed

in the vast coalmine of Cerrejon

that opened up the lost world of 60 million years ago.

But these ancient bones give only a glimpse

of the creatures that live there.

To see the past more clearly,

the team turn their attention to the animals of today.

After the students' discovery in the lab,

the next stop for the investigating scientists

is the collection of modern snake skeletons

at the Florida museum of natural history.

Its biggest specimen is from an anaconda,

the heaviest snake living today.

How will its backbone compare

with the giant vertebra from Cerrejon?

Bloch: We went and got a skeleton of a 17-foot anaconda,

which was the largest anaconda that we had in our collections.

That's a big snake.

The largest piece of the backbone of that snake,

and it was about this big,

compared to the vertebra that we've just unwrapped,

which was about this big.

So, you know, I thought, well, my goodness,

if this is 17 feet, then this thing must be 80 feet.

Narrator: The team is finding itself

swept up in an enduring pursuit...

The quest for the world's longest snake.

One pioneer was the Victorian explorer Percy Fawcett

who claimed to have seen a 60-foot-long anaconda

in the South American rainforest.

But he went missing in the forest

before supplying any evidence

and was never seen again.

In 1912, the former U.S. President Theodore Roosevelt

offered a prize at the Bronx zoo of $1,000

to anyone who could produce a snake

of more than 30 feet in length.

Explorers and collectors scoured the globe,

from Peru to the Congo.

But a 30-foot snake remained tantalizingly elusive.

A species from Asia, the reticulated python,

has come the closest,

measuring up to a staggering 28 and a half feet.

But not one snake has yet been brought forward

that can claim Roosevelt's century-old prize.

Zoos across the world remain on the lookout

for the longest snake.

One of the oldest is the zoological society of London,

where Ian Stephen is the resident snake expert.

Ian Stephen: Whether it's the biggest dinosaur on earth,

you know, the blue whale,

people are always fascinated by big animals.

It's almost every reptile curator's dream,

I think, sort of secretly

to have the biggest snake in the world.

Narrator: But the size of these modern snakes

is nothing compared with that

suggested by the find at Cerrejon.

After the discovery of the giant vertebra,

Jon Bloch contacted Jason head, an expert on extinct snakes,

at the university of Nebraska.

Bloch: We were unwrapping fossils from Cerrejon this morning,

we found something really incredible

that I wanted to show you.

Narrator: By now, more and more huge vertebrae

were being unearthed at Cerrejon.

Jon began by showing one of the smaller examples.

Bloch: I think it's a snake fossil, but it's big.

Yeah, sure.

Narrator: Jason still vividly remembers that video conference.

Jason head: Jon's students had actually realized

that they had a very large snake fossil.

And Jon brought it to the video camera,

and he held it up and said,

"look at this, I think this must be the world's biggest snake."

That's definitely a snake,

and that specimen is about the same size as Gigantophis,

so that's the same size as the largest known snake.

Narrator: Gigantophis, which Jason had recently measured,

was the largest snake so far known to have lived on earth.

36 million years ago,

it preyed on primitive elephants in the swamps of Egypt

and measured a colossal 33 feet.

Jason's world record holder was now under challenge.

Head: The vertebra he showed me was about the same size,

and I was kind of, you know,

it's big, but maybe it's not that big.

Bloch: Okay, yeah, we have others.

I mean, he was impressed, it was a big snake,

but he wasn't really taken aback, he'd seen bigger.

So, at that point, I felt like I hadn't really given him

the correct impression.

Narrator: Jon had a larger vertebra from Cerrejon

up his sleeve.

Head: And he said, "well, hold on, I'll be right back."

Bloch: So I went running out of the room

and grabbed the biggest one I could find

that we had unwrapped.

Head: He came back with a much bigger vertebra.

Bloch: This is bigger.

Head: Seeing him holding this, very excited, in his hand.

That is the world's largest snake, Jon.

I was absolutely surprised.

That's the largest snake I've ever seen.

That's got to be the largest snake in the world, Jon.

If you would have told me that there were snakes that big

in the fossil record, I probably wouldn't have believed you.

Bloch: That was impressive enough.

He said, "Jon, look at your office door."

And I looked over to the office door,

and he said, "if that snake were to come into your office,

it would have to squeeze through the doorway

as it was slithering in."

And that was enough to set the impression completely.

Narrator: By the end of the call,

Jason head was convinced Jon had found something special.

Head: Most of the other fossil snakes we find

are kind of in the vicinity of the largest estimates

of the biggest giant snakes today,

which has kind of suggested, at least to me, previously,

that maybe that was roughly the maximum size snakes could get,

either physiologically or ecologically.

I'm getting a flight ticket and heading down there right now.

Bloch: Okay.

Narrator: At the Florida lab,

Jason's first line of investigation

is into the kind of snake this is.

Is it related to a type already known,

or something completely new?

With only vertebrae to go on,

this is a complex task requiring an expert eye.

Head: In the case of snakes,

figuring out who's related to who

would be easy if we had complete skulls.

But most of the fossil record of snakes

consist of isolated backbones.

Narrator: But snake skulls are extremely fragile

and hard to find.

So Jason has to begin a process

of comparing these isolated backbones

with a huge range of snakes in his database,

both living and dead.

Head: In order to figure out who this animal's related to

and who it was, what we need to do is make comparisons

between subtle changes in the anatomy,

between this animal and other living and fossil snakes.

Narrator: All snakes have one thing in common...

They are a type of lizard that lost their legs

as they developed elongated bodies.

They may look similar to the untrained eye,

but their evolution is highly varied.

Head: Somewhere about 100 million years ago or so,

snakes evolved this elongate, limbless,

or limb-reduced body plan.

And in that body plan or that body form,

they immediately started inhabiting

different environments.

They were burrowers, they were swimmers,

and the body itself, the actual vertebral column

and the ribs and that muscular system,

that becomes the method of locomotion,

that becomes their means of moving around,

that snakelike motion that you see.

Stephen: It seems almost counterintuitive

that an animal should lose its limbs.

And yet the snakes are still with us today

and are actually one of the most successful groups of vertebrates

on the planet.

Narrator: Over their 100 million years, snakes have diversified.

Some families have developed super-toxic venom

with specialized fangs, like cobras, vipers and rattlesnakes.

Others don't use venom at all,

but kill by crushing the life out of their prey...

The constrictors.

From his initial comparison of the Cerrejon vertebra

with the backbones of modern snakes,

Jason soon concludes that it is similar to boas and pythons,

both constrictors.

Head: The group of snakes that it belongs to

are absolutely not venomous.

They, of course, acquire their prey in a very different way,

and that's the kind of iconic constricting behavior

that everyone thinks about when they think about boas

and pythons and anacondas and things like that.

Narrator: To advance their investigation,

the scientists must enter

the extraordinary and highly successful world

of the big constrictors.

How do they hunt, kill, breed, and adapt?

There's one surprising place to find out,

just 500 Miles from the lab.

Jon Bloch heads for the Florida everglades,

now home to one of the biggest snakes in the world.

It can grow to over 20 feet in length,

and it's not native to Florida.

It's the Burmese python.

Jon's guide is a local reptile expert, Shawn Heflick.

Before they go hunting, Jon shows Shawn the vertebra

from the giant snake from Cerrejon.

Bloch: We've got a snake for comparison.

Shawn Heflick: Uh-oh, you got goodies?

Bloch: Yeah.

What we've got here is the cast of the original bone.

This is one of the vertebra.

Heflick: Wait a minute, what?

Bloch: Yeah.

So this is a vertebra, so one piece of the backbone.

Heflick: Get out of here.

Wow.

That is impressive.

This is a modern-sized whale vertebra.

That's insane.

Bloch: And this isn't even the largest bone that we've found.

Heflick: I'm almost speechless,

because that is truly a monstrosity among snakes.

It's hard for me to conceive an animal of that mass and size

having lived on this planet.

Narrator: The snakes in today's everglades

may be 60 million years away from the lost world of Cerrejon,

but now, as then, they're certainly thriving.

Heflick: Seen a lot of pythons in this area right here,

it's got everything they need...

A lot of cover, access to water, a lot of prey.

Narrator: But there's a curious twist.

The Burmese python belongs

in the rainforests of southeast Asia.

It shouldn't be here at all.

In 1992, hurricane Andrew hit Florida.

Among its casualties was an animal warehouse

containing hundreds of Burmese pythons,

destined for the pet trade.

Around 900 escaped.

They flourished in the hot, humid conditions,

devouring everything in their path.

Over the past 19 years,

the number of pythons on the loose

is thought to have risen to 10,000.

Shawn Heflick is licensed by the state of Florida to catch them,

in an effort to keep the population under control.

Nothing is safe from these rampant pythons...

Birds, mammals, reptiles are all easy victims.

Even the top predators, the alligators, are potential prey.

It may be a long distant echo

of how Jon's giant snake once terrorized Cerrejon.

There are other snakes here, too,

like the eastern diamondback, a venomous rattlesnake.

Heflick: Be aware, you're in eastern diamondback territory as well.

Bloch: Okay.

Heflick: We've got some saw grass here, so watch...

Bloch: I see that.

Heflick: ...Watch your face as you pile through.

See, there's a lot of really good cover in here.

They're so hard to spot.

Narrator: Snakes are the snipers of the animal world.

First, find a good place for an ambush.

Modern or ancient, small or giant,

every snake needs somewhere to hide.

Bloch: Every once in a while I hear a little scurrying,

but I'm assuming those are just rodents.

Heflick: Yeah, a lot of rodents in here,

all these rock piles and all this cover.

There could be a 16-foot Burm right there,

unless it moves or you just happen to, you know,

catch a little piece of it,

you'd never know it was there.

Bloch: Sure.

Heflick: It's a needle in the haystack.

Narrator: Camouflage and concealment

are part of the snake's arsenal.

Their prey may move faster,

so they must catch it by the speed of their initial strike.

Heflick: Jon, look over here.

Bloch: Yeah, that's python, no doubt.

Heflick: Over there.

That's a good sized snake.

Bloch: This is not the whole thing, but it's definitely a snake.

That's got me excited now.

Heflick: Oh, now you believe me that there are pythons here.

Bloch: They're here. Okay.

Heflick: See if we can find a live one.

Bloch: Alright.

Heflick: I see, there's the fossil hunter in you,

you're still looking for...

Bloch: Yeah, this is the kind of thing I'm used to looking for.

Heflick: You're still looking for the dead stuff.

I can appreciate that.

Narrator: Like a modern snake,

the Cerrejon monster's forked tongue is a crucial organ,

sensing the world around it.

The fork in the tongue makes its surface area bigger

and more sensitive.

It may help snakes to detect the direction of prey

and other items of interest,

all the while staying hidden in the undergrowth.

Bloch: Oh, something?

Heflick: Like I say,

you'd almost have to step on it, you know.

Bloch: Something moved in there.

Heflick: You hear something?

Bloch: I did.

Heflick: Might be easier to find a 58-million-year-old animal,

doesn't run from you, huh?

Narrator: The search continues.

The everglades national park is 2,300 square Miles

of land and water.

The Burmese pythons have penetrated

deep into these wetlands, by swimming from island to island.

But the snake hunters' persistence

will shortly pay off.

Jon Bloch is about to see first-hand

what constrictors are capable of.

Heflick: Oh, right there, Jon, Jon, Jon.

Bloch: Oh, God, look at that's huge.

That's a big snake.

So you're gonna grab it by the tail?

Heflick: Yeah, we'll walk her back and, oh, yeah.

Bloch: Uh-huh.

Heflick: Not happy.

Now that's the difference between these.

This thing's strong.

That's the difference between these in captivity

and these wild caught ones, is not happy right now.

So the whole game on this, so now she knows...

Oh, that's a bad area.

Narrator: Though the python kills by constriction

and does not inject poison,

it still has a ferocious bite to grab its prey.

Heflick: That's a younger Burmese python.

Bloch: It'll be a second, she'll realize you're back there, huh?

Heflick: She wants to go, go, go,

and she's being restrained.

Narrator: Once the prey is in range,

the snake launches itself like a heat-seeking missile.

Bloch: Oh, yeah.

There we go. Nice.

Heflick: Okay, sweetie.

Bloch: Okay.

Heflick: Switch hands. Yeah.

Bloch: Beautiful.

Heflick: She's not happy. Bloch: No, she's not.

Heflick: Not happy, but if you can do me a favor

and grab that tail?

Bloch: Yeah.

Heflick: She's gonna musk.

No, keep it back, keep it back, keep it back.

[Laughter]

That's what they do as a defense mechanism.

Narrator: The snake sees Jon as a predator.

Its instinctive reaction

is to squirt the contents of its bowels all over him.

Heflick: They're going to musk, they're gonna, you know,

evacuate their bowels on a would-be predator.

Bloch: Okay.

Heflick: And that's enough to get anybody to say,

I don't know if I want to eat this thing or not.

But let's unwind her.

Bloch: Okay.

Heflick: Just here.

Yeah.

Bloch: Oh, she's heavy.

Heflick: She's powerful, isn't she?

Bloch: Yeah.

She also has recurved teeth.

Oh, did she get you?

Heflick: Yeah, just one little Nick and you see, you know,

the teeth are pretty sharp, like hypodermic needles.

Narrator: The ancient snake's recurved teeth

lock on to its prey.

The more the prey struggles, the deeper the teeth go.

Stephen: The bite is really just to secure the prey.

So the snake is gonna obviously strike,

bite the prey item,

and literally get it secure in its jaws and then constrict.

Narrator: 60 million years ago, as today,

the constrictor throws coils around its victim

and crushes it.

Constriction is unique to snakes.

Jon's getting his first view of it.

Heflick: She's got a pretty good lock on my arm.

Bloch: Yeah, I can see that.

Heflick: We need to get her in a bag,

I think my hand might be turning purple.

Stephen: When you're handling snakes,

sometimes they then start constricting your arm.

And it's when they do that, that you actually realize,

wow, these snakes are just incredibly powerful,

a muscle machine, if you like.

Narrator: A constrictor this size

can exert a pressure of 30 pounds per square inch.

On the human chest,

it's equivalent to being crushed by a small car.

As snakes get bigger,

their muscles generate ever more force,

and they can throw more loops around their prey.

Heflick: If I was a prey item,

she would constrict me until she constricted me so much,

there was vasoconstriction constriction, and my heart

would literally almost explode,

because, you know, it just stops it,

and there's so much pressure on your circulatory system,

as well as suffocating you as well,

you know, the prey item gets suffocated.

Narrator: Constriction is so effective

that snakes can take on the largest prey.

In Cerrejon, 60 million years ago,

it would have been a battle of the giants.

Heflick: Magnificent.

I don't know how you don't look at this and not go, "wow."

Bloch: No, it's gorgeous.

Heflick: Truly a gorgeous animal.

Bloch: But this is gonna come out of this habitat.

Heflick: We have to remove it, it doesn't belong here.

Bloch: Well, that can be useful for us, because...

Narrator: Despite Shawn's best efforts,

it's an ongoing battle to keep the pythons in check.

The most effective control so far has been cold winters.

Big snakes need heat to thrive

and are vulnerable to low temperatures,

a phenomenon that may become relevant

in explaining why the giant snakes at Cerrejon died out.

Heflick: Big female.

Narrator: But for now, there are more immediate questions.

The initial evidence suggests

the Cerrejon snake was the biggest that's ever lived.

But precisely how big

and what type?

In the Florida lab, Jason head is narrowing the options

by comparing the Cerrejon fossil

with vertebrae from living snakes.

The final choice comes down to a python

or a group of so-call boid snakes,

that includes boas and anacondas.

Head: If we compare the fossil

with the vertebra of this living python,

what we can see is that

they're actually very similar to each other.

However, there is a key feature of the fossil.

Specifically, these two holes

that we see on either side of the vertebra right here,

that are not present in pythons.

Narrator: Having eliminated pythons,

Jason knows what type of constrictor

the Cerrejon giant must have been.

Head: It actually shared characters

with boa constrictors,

suggesting that they're closely related to each other,

despite being very different in size.

Narrator: The Cerrejon snake was a gigantic relative

of boas and anacondas,

snakes that are still alive in South America today,

though a fraction of the size

of their 60-million-year-old forebear.

Calculating the Cerrejon monster's exact size

requires an ingenious and painstaking set of calculations

from the vertebrae the team had collected back in Cerrejon.

Bloch: In order to tell how large a snake is,

you have to know what part of the body the bone is from

within the vertebral column.

And the reason for that

is because within the same exact skeleton of a snake,

you can have very small ones and very large ones,

depending on where you are in the position.

Narrator: The first question is

how to work out where the fossil vertebra lay

in the giant snake's spinal column.

David Polly of Indiana University in Bloomington

is drafted in to make a mathematical model.

The first clue is the minute changes

in the shape of a snake's vertebrae,

which depend on where they're situated.

David Polly: One of the things about snakes,

even though they look like they're a long tube,

they do different things with their neck

and with their body and with their tail.

Sometimes they strike, and sometimes they're slithering.

So they've got lots of different muscles.

Narrator: It is these muscles that dictate the tiny differences

in each vertebra's shape and proportion.

Polly: As you go from the head of the snake

to the tail of the snake,

you get different lengths of these projections

and different proportions.

Narrator: For his model, David Polly first creates

a mathematical map of the Cerrejon vertebra.

His ultimate aim is to work out

exactly where it fits in the snake's body.

Polly: So what we're looking at here

is a stylized representation of this.

This point here is this point, this point is the top up here,

and these, this down here.

So this represents the shape of this particular vertebra.

Narrator: Then, the shape and gradient

of hundreds of vertebrae in modern boid snakes

from every part of the body are also entered into the model.

Finally, the Cerrejon vertebra is matched against them.

Polly: What we did mathematically

was we took this gradient from one to the other

in all of the snakes

and found where it matched best

as you went from the front to the back.

Bloch: We could then measure the shape on this vertebra

and then with some degree of likelihood,

be able to place it within some position in the body.

It's a fairly simple idea,

but it actually takes quite a bit of work

and took us the greater part of a year to do.

Narrator: With the ancient fossil embedded into the snake map,

it is now possible to reconstruct

the size of the snake.

In the courtyard of the Florida museum,

Jon Bloch and Jason head are ready for the big revelation.

Bloch: Where would this go, do you think, in the body?

Head: So that specimen would be just over halfway

between the head and the tail,

so just about here.

Bloch: Okay.

Narrator: The result is awe inspiring.

The longest modern snake, the reticulated python,

measures 28 feet.

The biggest previous fossil snake, Gigantophis... 33 feet.

The Cerrejon snake smashes the record.

48 feet long,

it is the longest snake in world history.

Bloch: That's a big snake.

Head: This is a huge snake.

Narrator: This is just the first specimen from Cerrejon.

There could be even longer snakes out there.

And further mysteries remain.

How did it live? What did it eat?

What did it really look like?

Above all, how could it possibly have grown so big?

It's time to name it.

To reflect its ancestry, as well as its enormity,

it will be called Titanoboa,

a boa of Titanic proportions.

In honor of the Colombian mine where it was found,

its full name... Titanoboa Cerrejonensis.

With its credentials proved, titanoboa can be launched,

a creature to make headlines and capture the imagination

of the scientific, phobic and expert across the world.

Stephen: Wow, you know, this is an amazing animal.

It's just one of those things that you know

you're not gonna have happen

that many times in your lifetime.

Finally, snakes are on the map.

Bloch: Many people's reaction is just sort of that of horror.

There's a certain fear of snakes that exists out there,

and I think for a lot of people

that's sort of the root of the fascination.

Narrator: To fully comprehend titanoboa,

it needs, somehow, to be seen.

Snakes are not just bones,

there's also flesh on those bones.

At Indiana university, Bloomington,

a snake is coming under a highly expert knife.

Matt Rowe used to be a Sushi chef,

now his skills are unveiling the complete snake.

The meat, a delicacy in many exotic cuisines.

The skin, used for ladies' handbags, belts and boots.

But the most striking thing Matt can reveal

is how much larger a snake becomes

when its bones are fleshed out.

Matt Rowe: Alright.

So this is the vertebra inside of the cross-section here.

It's a little bit difficult to see at this point,

because they're relatively small

in comparison to the size of the cross-section,

and you can see the centrum of the vertebra here.

In our research, in the dissections that we've done,

the size of the vertebra in comparison to the snake

has always surprised me,

in the sense that they are always much smaller

than I would think.

As you can see here,

a small vertebra does not necessarily indicate

a small snake.

Narrator: In some big living snakes,

the ribs are about five inches long.

Scaled up to the Cerrejon giant snake,

the ribs must have been more like two feet long,

with a wall of muscle strong enough to crush a rhinoceros.

To recreate the full glory of titanoboa,

a Canadian model maker, Kevin Hockley,

is drafted into the team.

He's commissioned to build a life-size replica.

His previous life-size creations include two animals

that also once seemed the stuff of myth and fantasy,

but are monstrously alive and well today...

A narwhal and a giant squid.

Titanoboa, though long dead, will overwhelm even them.

Kevin Hockley: It's a huge snake

and bigger than any living snake

and certainly bigger than any snake that I've made to date.

And the other challenge was,

there's only a few actual fossils of the bones,

so we're going by a scientist's speculation

as to what it actually looked like.

Narrator: One key part is missing...

A fossil of Titanoboa's skull.

Kevin is starting his model from the tail end,

in the hope that Jason head and his colleagues will find one.

Head: He's a biologically realistic model.

Narrator: Only with the head in place

will we know exactly how titanoboa looked.

Head: And it gives you both the biology and the fear factor,

the punch, that would get people interested.

Narrator: Back at Cerrejon, the fossil hunters scour the mine

for the skull bones whose fragility

makes them so elusive and rare.

They know a headless snake

will always be a story without an end.

And other mysteries remain...

What did titanoboa eat?

How did it hunt and reproduce?

One place on today's earth can provide some clues.

The flooded grasslands of the Venezuelan llanos.

Here, the average temperature

is more than a sweltering 80 degrees.

Though this is not a rainforest,

the similarity of the animals in these sultry wetlands

makes it almost a mini Cerrejon.

Turtles and caiman flourish,

and alongside them,

an animal with similar habits to titanoboa,

the heaviest snake in the modern world...

The green anaconda.

Jesus Rivas is the leading authority on the anaconda.

He spent 20 years in these wetlands,

studying them close up and what they like to eat,

like this turtle.

Jesus Rivas: Wow, it's a monster!

Narrator: Titanoboa may have been 10 times as heavy,

but Jesus believes the anaconda gives the best possible insight

into its world.

Most boas live in trees,

an unlikely move for titanoboa.

So the anaconda, also one of the boid group of snakes,

offers the best comparison.

Rivas: Titanoboa is an aquatic, tropical snake

that is very related to anaconda.

I can't think of a closer model of standard snakes

to understand what titanoboa was like than living anacondas.

Narrator: Jesus walks these snake-infested swamplands barefoot,

so he can feel reptiles he can't see.

There are leeches, stingrays, caiman, crocs, and piranhas

in his path.

But it's worth it

to get to grips with these magnificent but shy creatures.

Suddenly, Jesus feels a familiar slithery presence underfoot.

Rivas: Got something for ya.

Okay, got you.

Narrator: Jesus has found anacondas

measuring a massive 18 feet.

Rivas: Just like they're three and a half.

Narrator: He knows that dry land is their enemy.

Rivas: Okay.

Narrator: Something that must have also been true

for titanoboa.

Rivas: I don't think titanoboa, being that large,

would have been very easy to crawl through dry land,

maybe for very short time.

Narrator: Titanoboa weighed as much as 20 people.

Movement on land was a constant fight with gravity.

Like the anaconda, its friend was water,

where it becomes effectively weightless and faster.

Today's snake habitat in Venezuela

reinforces the evidence that Titanoboa's kingdom

was a rainforest water world.

Head: And this is a very large,

either a slow-moving river system,

or kind of a backwater of a major river system.

So what we have is a big, wet landscape full of water

with a lot of aquatic snakes in it.

Narrator: On land, Titanoboa's weight is suffocating it.

Sliding into the water, it is coming home.

In this ideal environment,

it becomes the ruling predator,

a lurking killer.

Despite their lack of legs or fins,

snakes are natural swimmers,

faster than humans.

The secret is their flexible spines.

They turn themselves into a fluid "s" shape,

using their whole body to carve through the water.

The anacondas of the Venezuelan llanos

are the nearest living echo of the long lost snake

and the world it dominated.

And to get even closer to their extraordinary discovery,

the scientists must encounter the anaconda face to face.

But they won't give up their secrets without a fight.

Jon Bloch and Jason head,

experts in the prehistoric world,

land in the Venezuelan llanos, close to the equator.

It's oppressively hot and humid.

Hell for humans,

paradise for the biggest snakes on today's earth.

Jon and Jason have come in search of the green anaconda,

which thrives in this steaming swamp.

The anaconda's lifestyle is the closest they can find

to the giant snake, titanoboa,

which flourished in Colombia 60 million years ago

in the lost world of Cerrejon.

Their guide is Jesus Rivas,

the world's leading expert on the green anaconda.

He shows the new arrivals that the best way to find one

is to feel for it with bare feet.

Alarmingly, he can also tell them

that anacondas can be lethal, even for humans.

Rivas: An anaconda is potentially a danger for a person

because of the sheer size.

They're generalist predators.

As long as capacity of killing a person,

definitely can kill a person.

Narrator: Anaconda mainly hunt in water,

where they're hardest to spot.

Just like titanoboa, lurking beneath the surface,

waiting for unsuspecting prey to pass by.

Dead still, heart, a silent murmur,

holding its breath for up to 45 minutes.

Waiting for the perfect prey

until the moment comes.

Head: Oh, you got tagged.

Bloch: It's all right.

He came out of nowhere,

it was like the monster from the deep.

Narrator: Jon has suddenly become the target.

Rivas: Bad girl.

Let it bleed, let it bleed.

Bloch: It hurt, there's no doubt it hurt,

and it's bleeding a lot.

Man: Does it hurt a lot?

Woman: We have band aids, so.

Bloch: Is that normal to puff up like that?

Woman: No.

Man: Probably need to put something over it.

Narrator: Jon will later find out

the anaconda has left two vicious teeth buried in his leg.

It saw him either as potential prey or as a threat.

Rivas: Welcome to the club!

Bloch: Oh, thank you.

[Laughter]

Narrator: To Jesus, it's part of everyday life in snake land.

The anaconda that bit Jon was relatively small fry.

Even the largest anaconda here would be dwarfed by titanoboa.

Bloch: Oh, my God, look.

Narrator: But whatever the difference in size,

they eat the same way.

Rivas: Look how skinny he becomes.

That looks like a Galapagos, like a turtle.

Bloch: So there's an example of an anaconda with a turtle in it,

you think?

Rivas: That's right.

Bloch: That is pretty interesting,

so sideneck turtles, just like we have in Cerrejon.

Narrator: The anaconda has swallowed a meal

wider than its own body.

Man: Oh, look at that.

Rivas: Her tail looks fine.

Bloch: Okay.

Rivas: Not a catcher, sorry, girl.

Look at this, look at the piece, the chunk missing over here.

Come on here, come on here, look at the chunk of flesh.

Narrator: Jesus spots a wound on the anaconda's side.

It was inflicted by the prey.

Rivas: Maybe it's a baby Capybara.

It's expensive for a snake to take a meal.

Bloch: Yeah.

Narrator: On every hunt, a snake risks its life.

It's kill or be killed.

Rivas: Okay, let's move around, let's move away,

leave her address her meal, we don't want her to lose it.

Narrator: The anaconda wants some privacy and safety

to digest its catch.

These snakes don't stop at turtles.

They also prey here on caiman, a type of crocodile.

Snakes have always been willing to take on the largest prey,

both now and 60 million years ago.

Is any animal safe from titanoboa

in Cerrejon's lost world?

Even the half ton blunt-nosed crocodile is at risk...

...unable to escape the giant snake's recurved teeth.

Crushed by coils of muscle,

delivering 400 pounds per square inch of pressure.

Each time the crocodile's chest moves,

titanoboa tightens its grip.

Inducing unconsciousness,

then cutting off its victim's blood...

...until death.

There's movement in the water.

Rivas: That's what we're here for.

[Indistinct] What do you have?

Bloch: Oh!

[Laughter]

Narrator: This anaconda's big enough to crush a human.

Rivas: Woo!

She wants to give me a kiss, look at that.

Or is it Jon you like?

Narrator: Four human adults struggle

to resist the massive, twisting force of the snake's muscles.

Rivas: She is...

Bloch: Strong.

Narrator: Holding it behind the head

is the only way to make it safe...

Rivas: Why won't you hold his ears?

Narrator: ...As head movement controls the body's twisting.

This snake is big, powerful and hungry.

Rivas: Let me do that. Bloch: I've got it.

Rivas: Let me hold the first part.

This girl, this size will feed on anything.

Small crocs, turtles, deer, small children, anything.

[Laughter]

Bloch: So this is probably about the size

of a juvenile titanoboa, maybe about a year old?

[Laughter]

Rivas: How long do you reckon this vertebrates are?

Head: The vertebrae on this animal?

Rivas: Yeah.

Head: Be about that wide.

Narrator: Snakes keep growing throughout their lives.

The bigger ones are the longest lived and the most successful.

Bloch: No, no, no, titanoboa is like that.

Narrator: Given the size of this anaconda,

it seems almost unbelievable

that it's nothing compared with titanoboa.

Head: No, Titanoboa's probably 60, 70 centimeters wide.

This snake looks like she's got a diameter

of about nine, maybe 10 centimeters at the widest point,

which is one-fifth to one-seventh

the width of titanoboa.

Rivas: This is a very skinny snake for her size.

If she were nice and plump,

she would be probably 10 inches across.

Head: Okay.

Rivas: She probably gave birth last year,

for how skinny she is.

And she probably is aiming for a Capybara or a good caiman

or something to make up for the energy lost.

Narrator: This is as close as the scientists can get

in the living snake world of today

to the lost world of titanoboa.

Rivas: Okay.

Let's go home.

Narrator: The habitat and plants may be different,

and this is not a rainforest.

But the similarities in the mix of animals are striking.

Head: If you think about this ecosystem,

how many snakes we found just today

and how many caiman we've seen and how many turtles.

Where we're standing right now, that's basically Cerrejon.

Bloch: It's really an incredible experience

for me to be able to see this habitat like this.

At Cerrejon, we find this big layer with, you know,

all of these skeletons of snakes closely spaced,

and you think, well, how could an ecosystem sustain

that many snakes in such a small place?

And then here we're finding snakes all over the place,

together, giant, huge snakes.

Narrator: The team finds five anacondas in just one day.

Jesus has counted 2,000 of these snakes here.

Bloch: Watch your hands.

Narrator: Cerrejon would probably have been the same.

Not just one or two titanoboa,

but thousands.

Rivas: Go for it.

There you go.

Bloch: Beautiful, look at that.

Narrator: As the trip ends,

Jon Bloch turns snake catcher for the first time.

Head: Gorgeous snake.

Rivas: Your first worry is to protect the head.

Their muscle cladded, all the things protection,

but the head is very sensitive.

So when they feel in danger,

they'll wrap their head around anything.

That's what she was trying to do

to protect her head between her loops,

that's what tangles you up.

Bloch: Got it.

She's got me around the neck.

Do you want to help me there, Jason?

[Laughter]

Thank you.

You're a good friend.

Head: Oh, that's fantastic, look at that.

Narrator: Jon and Jason's work, both in the lab and the field,

is fed back to their model maker Kevin Hockley

thousands of Miles away in Canada.

But to complete his recreation of titanoboa,

he urgently needs a skull.

The team of scientists investigating

the giant prehistoric snake, titanoboa,

return to the coalmine at Cerrejon in Colombia,

the place they first discovered fossils of its vertebrae.

They're in a race against time

to find the one missing piece in their Jigsaw puzzle,

a remnant of Titanoboa's skull.

Soon, the diggers will penetrate beneath the seam of coal

that revealed the lost world of 60 million years ago.

Bloch: The operations at the mine

will eventually destroy this hill completely

and probably this will be our last trip here,

on the LA puente pit that's been so good to us

in terms of collecting.

This is the only place in the world

that we've ever, in fact, found titanoboa, for example.

Narrator: The mine has not just produced titanoboa,

it has revealed a dazzling variety of giant animals.

One of the most remarkable is the freshwater turtle,

discovered by Colombian scientist Edwin Cadena.

He could hardly believe his eyes

when he began scraping away at the first fossil.

Edwin Cadena: So I start working with this screwdriver,

carefully removing all the sediment

that was covering this specimen.

And wow, it was a really, really nice moment

for me to see this almost two-meters-long turtle

coming at the surface.

This is the head of the turtle and this is the shell,

the carapace and the plastron of the turtle.

It was a surprise for me.

Narrator: The final measurement turns out to be

an astonishing eight feet, as big as a dinner table.

The lost water world contains strange species,

like the lungfish, capable of breathing in surface air.

It grew as big as a man.

And there were massive crocodiles.

Hastings: So we have three different types

of crocodile relatives from Colombia,

we have a small-bodied form with a relatively narrow snout,

good for small prey items.

Medium sized, long-snouted form here,

this lower jaw is very good for catching slippery, quick fish.

Here is a blunt-snouted crocodile

with a really short snout,

which is perfectly adapted for really tough foods.

So something like a turtle shell

that needs a lot of force in order to deal with that.

When you have your upper and your lower jaws

coming together like this,

you have to have a really strong tooth

in order to withstand that pressure.

And these blunt, round teeth are perfectly adapted

for taking on tough foods like turtle shells.

Narrator: Pieced together, the crocodile measures 15 feet long.

The team has complete crocodiles and complete turtles.

What they're desperate for is a complete titanoboa.

But there's still no skull.

Finding a skull remnant is almost impossible.

They're fragile shards that have disintegrated

over the millions of years.

To give the team the best possible chance,

Jason head, their expert in extinct snakes,

makes his first visit to Cerrejon.

Head: Now, of course, we don't really have a lot of skulls

for the fossil record of snakes, 'cause they're very light,

and they break apart after the animal has died.

Narrator: Even though they haven't found a skull,

each time they return to the mine,

the team does discover more and more evidence of titanoboa.

One find is extraordinarily intact.

Head: This is a really incredible specimen.

This snake, when it died,

was roughly angled so that the front of the animal was here,

probably coming around

and going all the way around

and then coming back toward the tail here.

Bloch: How big do you think this snake was, about?

Head: We're probably looking at a skull,

based on the relationship

between skull size to body length

in living boas and pythons,

of about this long from the tip of the snout

to the back of the skull.

Bloch: That's the size of a lot of the crocodiles

we get out of here.

Head: That's right.

This is a big animal,

this is the largest animal in the ecosystem.

Narrator: Despite this great spread of ribs and vertebrae,

no skull is found.

Bloch: Finally back here...

Narrator: But the size of this fossil snake raises the question

of why some titanoboa seem to be so much bigger than others.

The answer to that lies here in the Venezuelan llanos.

Jesus Rivas has stumbled on something

that's rare for humans to catch sight of.

Rivas: Right here, this is a small anaconda,

it's a male-sized anaconda.

And it's wrapped around something.

At least one male, could be two, but hard to tell for now.

And the female's body is definitely in that direction.

So then I dig it out.

Yeah, that is the female's body for sure.

And that is a third.

Don't bite me, please.

Narrator: This is a mating ball,

several male anacondas wrapped around a female.

The males are competing to mate with her.

Only one will succeed.

Rivas: He's leaving.

Two boys.

Second boy is here.

There's a third boy.

Narrator: Not surprisingly,

the male anacondas are angry at being pulled off the female.

Rivas: Oh, there you go.

Grab it, grab you, it doesn't matter.

[Laughter]

She was tagged.

The snake tagged her, look. [Laughs]

Oh, beautiful, look.

I need to see the head, which is somewhere here.

Now she's backing up.

Coochie, coochie, coochie.

Okay, got you.

Oh, she's a big one! Woo!

Narrator: This anaconda is 15 feet long,

a huge snake in today's world.

Rivas: Okay.

Narrator: The reason for the snake's size is simple.

She's female.

Rivas: She had four males with her.

You can see the difference in size,

how much smaller the males are.

Narrator: Based on living anacondas,

it is likely that in the lost world of Cerrejon,

the female titanoboa is also bigger and deadlier

than the male.

Males avoid females most of the year for very good reason.

They're in danger of being eaten by them.

But in the mating season,

chemical signals in the water show it's safe to approach.

And then, the fight is among the males.

The wrestling can last for weeks,

as the males try to push each other aside.

Until, finally, one manages to mate.

The pregnant female breaks off,

her young now growing inside her.

She's stored enough food in her body

to survive the seven months of pregnancy.

She won't eat again until she's given birth.

In the autopsy lab at Indiana university, Bloomington,

grad student Beth Reinke shows the huge number of eggs

a female python carries.

Beth Reinke: These are all eggs.

I see 29, 30 right now, 31, 32.

Narrator: In the female titanoboa,

there may be as many as 100 offspring.

After seven months, she's ready to give birth.

Head: The baby snakes are in a little, tiny shell membrane,

they punch through that,

and then they actually leave the mother,

in a way that's very similar to modern birth in most mammals.

Narrator: Titanoboa is likely to give birth in the water,

but may sometimes do so on land.

The babies are already over three feet long at birth,

as big as some modern snake adults.

Their size will be their only protection.

Head: Once the babies hatch,

they're pretty good in terms of taking care of themselves.

They're fully functional, they're able to hunt,

they're able to move around.

All their senses are fully developed.

So they're pretty good to go.

Narrator: Female Titanoboas do not mother their children.

The only attention they pay them

is to eat any that don't survive birth.

After abandoning the newborns,

the mother titanoboa heads off in search of prey

to relieve a hunger grown ferocious

from seven months without food.

The giant fossil at Cerrejon could be one of those females,

but the skull still eludes the searchers.

Head: If we are gonna find one, it should be over here.

Maybe we should think about searching off in this way,

excavating more of the hill.

Bloch: All we can do is look.

Head: That's right, let's do it.

Bloch: Looking for fossils can be a little bit

like searching for a needle in a haystack.

If there's going to be a skull,

it should be over here somewhere.

Narrator: Finally, with time running out

and the ever present threat

of the mine's need to resume digging,

a Colombian grad student strikes gold.

Not one, but three skull bones.

Head: This is a once-in-a-lifetime discovery,

really, this is just amazing.

For somebody who has gone around the world

and picked up vertebrae,

to actually pick up pieces of the skull

is an absolutely unique and unbelievable experience,

it's almost indescribable.

Those three bones include parts of the lower jaw,

and you can see right here,

these are the tooth positions where teeth would have been

when the animal was alive.

And this is actually a bone of the jaw joint.

This is the back of the skull,

and right here is where the lower jaw

actually connects with the upper jaw.

So up here on us.

From these three bones,

we can make inferences about its ecology, where it lived,

what it ate, how it behaved, how it reproduced,

all of the aspects of its life history.

Narrator: The precious skull fragments are carefully packed up

and flown back to the museum for analysis.

They are the clue to exactly how and what titanoboa ate.

Head: Turn that around.

This piece of the jaw of titanoboa

corresponds to that part of the jaw in a living snake.

Bloch: Wow, look at that, yeah, right.

Narrator: Jon and Jason fit the bone fragments

to positions on the skull.

Titanoboa's head begins to take shape.

Bloch: Great, so that would be...

Boy, look at that.

So this jaw would have been,

there would have been a little bit more on the front.

Head: The skull of this animal would be about that long.

Bloch: Fantastic, and we have some other pieces here, too.

Narrator: Even more important

than the huge size of titanoboa's head,

is how wide it can open its mouth.

Its gape determines what it can eat.

Head: They have these very long lower jaws,

with the jaw joint suspended far behind the back of the skull.

So when they open their mouths, this jaw swings down

and gives them a very, very, very wide gape.

Bloch: Okay.

And then it would have swung,

basically, at the back of the jaw.

Head: Exactly.

Bloch: It would have swung down. Boy, look at that.

So how big?

Head: It would have had a gape, probably about like that.

Bloch: At least, right?

Head: Yeah. Bloch: Yeah.

Head: Now also the lower jaws are actually separate,

so that when the lower jaws open, when this swings down,

the lower jaws will actually spread

wide apart from each other.

So titanoboa could have had a gape that wide.

Narrator: Even modern snakes display appetites that defy belief.

In the everglades, a large python once swallowed

an alligator as big as itself.

It didn't end well for either of them.

The snake exploded.

But prey like that was easy meat for titanoboa.

In ancient Cerrejon, there were monster meals

for a monster appetite.

The biggest lungfish, at 10 feet long,

a nice little entree.

The crocodiles, 15 feet long and powerful.

Satisfying as the main course.

Perhaps only one animal would have been too big

for even titanoboa to consume...

The giant adult turtle.

Cadena: They've got really thick shells,

and that means a lot of bone for a snake to get, digest.

So it's really not a good idea for a snake to get something

that is gonna stay in your stomach for so long,

because it has so much bone on it.

So, for the largest turtles at Cerrejon,

they had so many chances to survive,

because the snakes probably preferred to eat crocodiles

or other small animals.

Narrator: Titanoboa's ability to swallow prey

so much bulkier than itself is extraordinary,

and its solution, the same as for all snakes.

Stephen: Once they're sort of sensing that the prey's dead,

and they sort of figure out where the head of the prey is,

and then they start to eat the prey.

Snakes, obviously, are not like people.

They don't have hands

that they can shovel food down their throat.

They've got a left and a right jawbone.

So that degree of flexibility

enables them to eat much larger prey.

So they can almost walk their jawbones across their prey.

And if you imagine a combination of muscle contractions,

their recurved teeth, all help sort of bring that prey

into their mouth and into their throat.

Narrator: Flexible ligaments allow titanoboa

to stretch its jaw wider and wider apart.

Little by little, it maneuvers its jaws over the crocodile,

dragging it into its throat and down into its stomach.

The next challenge is digesting.

Reinke: So this would be whatever the snake last ate.

This is the stomach, and we cut right through

in our cross section, whatever the last prey item was.

So all this brown, gray, hairy area is the prey,

and I'll cut open the stomach some more,

so we can...

...get a better view of him.

There we go.

Here's some ribs.

Rowe: Here's the tail.

Reinke: Oh, yeah.

Narrator: This snake's prey was swallowed whole.

Reinke: Oh, is that the skull?

Rowe: That should be the skull.

That looks to be a rat.

Reinke: Yep.

Narrator: All the meat is stripped from the rat,

even the bones will end up being eaten.

Rowe: Rather large rat.

Reinke: Yeah, very large rat.

I mean, you can see here,

there isn't really that much fat or soft tissue anymore,

it's mostly the bones, the connective tissue,

and a lot of the fur.

But all of it will be broken down along the way.

Everything goes, it's pretty cool.

Narrator: For titanoboa, the kill is the easy part.

The effort of constriction is nothing to what comes next.

For titanoboa now has to digest

half a ton of blunt-nosed crocodile...

Skin, bones, everything.

Its stomach stretches,

and its temperature rises from the energy needed for digestion.

Hydrochloric acid fills the stomach,

slowly dissolving bone and tissue to liquefy it.

It may be its only meal in a year.

With a skull found, titanoboa's model maker Kevin Hockley

can complete his creation.

Shaping the head is the most complex part.

This face has not been seen on earth for 60 million years.

Hockley: I kind of have a visual in my mind

of what the shape it's supposed to be,

and I arrive at that mental image

by going over all my records and material

and try and picture it without all the chunks on there,

and then just start whittling away

all the pieces that don't belong.

Narrator: The model maker is not just conjuring an image of the snake,

he's creating the exact individual

from that initial vertebra,

based on the scientist's years of work.

A real 60-million-year-old creature is coming back to life.

But one overriding mystery remains.

How on earth did it get so big in the first place?

Bloch: Why aren't there snakes that big today?

Why are they so large in the past and not so large today?

What made titanoboa into a giant?

Narrator: What was it about Cerrejon's lost world

that was so different?

Bloch: The first possibility

that we thought quite a bit about,

in terms of why titanoboa would have been so large,

is that maybe what it was eating was larger.

Narrator: Cerrejon was not just a water world of giant snakes,

there were giant crocodiles, turtles and fish,

a food chain of monsters to be eaten by monsters.

And the skull bones of titanoboa

prove that its gape was big enough to eat almost anything.

But why were all these animals so big in the first place?

One answer is emerging... Temperature.

Mammals are warmed by the energy they get from food.

Snakes and other reptiles, which are cold-blooded, are not.

Instead, their body temperature is controlled

by the climate around them.

In Venezuela, Jesus Rivas has been experimenting

with anacondas to show how this works.

Rivas: We need a transmitter.

Woman: Which one is that?

Narrator: He uses a transmitter

to keep record of the snake's body temperature.

Rivas: This is a transmitter we're gonna give her.

It has a temperature sensor encapsulated in the resin.

It's a small thing, it looks a little rough,

but beware that she can swallow a full-grown caiman,

so this is not even a snack.

Come on, girl.

I knew you were going to do that.

Yes, that was.

It's difficult to overcome her muscles

and get it far enough down.

But I think now the transmitter,

I feel it all the way here,

so I think it's deep enough now that it should be okay.

Okay.

Good girl.

Narrator: With the radio transmission,

Jesus can trace his anacondas over years of life.

Man: Look at her.

Get a picture, Roseanne, if you can.

Rivas: Beautiful girl.

That's the best part of working with snakes,

letting them go and seeing them swim away.

Narrator: Jesus' measurements show

the snake's body temperature goes up and down,

in a way that matches with extraordinary precision

the changing temperature of the world they live in.

And it's temperature that determines

how big a snake can grow.

Head: In order for a cold-blooded animal

to reach a certain size,

the bigger they get, the more warmth they need.

So, to get a big snake, what you need are very hot environments.

Narrator: The distribution of snakes in today's world

shows the direct correlation between temperature and size.

In mild climates like Great Britain,

there's nothing bigger than a six-foot grass snake.

In the central United States,

gopher snakes at eight feet are the largest.

And in the heat of the Amazon basin,

there is the anaconda, up to 25 feet long.

In the modern world, that's about the limit.

Head: In cold-blooded animals, the ultimate regulator

is always going to be climate, it's gonna be temperature.

Narrator: Titanoboa's size is evidence

of a hotter temperature, 60 million years ago.

There's further support for a warmer climate,

from a much tinier piece of evidence.

The humble leaf.

A decade ago, fabiany Herrera discovered

the very first leaf fossil

that revealed the lost rainforest

that led to titanoboa.

Ever since, he's been scouring the area around Cerrejon,

comparing present with past.

Herrera: The fossil plants that we're finding on Cerrejon

are extremely similar

to the plants that we see today in modern rainforests

in South or central America.

Some of the plants that we have today,

that are present at Cerrejon 60 million years ago,

are the legume family or the bean family.

We also had the chocolate family, the banana family,

the palm family, the avocado family.

All the ones that you see today

in modern rainforests in South America.

Narrator: A plant's leaves are a way of measuring temperature.

The edge is where a leaf loses vital water.

In hotter climates, it needs that water more than ever.

Leaves with smooth edges lose less water to evaporation

than leaves with jagged edges.

The higher the proportion of smooth-leaved species,

the hotter the climate.

Herrera: What we are finding at Cerrejon

is that even more of the species have the smooth edges,

and that indicates a higher or a hotter temperature

60 million years ago.

Narrator: For Jon Bloch and Jason head,

as they near the end of this part of their journey

into Cerrejon's lost world,

this research on temperature has produced

a fascinating byproduct.

There's a limit to how high a temperature leaves can show.

But they believe that the size of titanoboa may be able to show

how hot the lost world of Cerrejon really was.

Bloch: We use titanoboa as a thermometer

that we dipped into the past to tell the temperature.

It provided us with a new way of telling temperature in the past

that had not been used before.

Narrator: They've calculated that

titanoboa can only have grown so big

at a rainforest temperature 60 million years ago

significantly higher than in the rainforest of today.

Head: Our estimates are basically

between about 29 to somewhere of 33, 34 degrees.

Narrator: That's a range of 84 to 93 Fahrenheit,

average annual temperature.

At times, it must have soared far higher.

It's a piece of research with intriguing implications.

It suggests that 60 million years ago

the rainforest of Cerrejon thrived

at a very high temperature,

which, according to some of today's computer models,

would kill off its plants.

So Cerrejon appears to show that global warming

won't necessarily destroy the rainforest.

But could it lead to much bigger snakes?

Could titanoboa itself make a comeback?

Bloch: It's theoretically possible.

Something like an anaconda, for example,

could become as large as titanoboa

if the temperature on the planet were to become that warm again.

Narrator: The future remains speculation.

The reality of the past is that, in the end,

titanoboa disappeared.

Whether cooling temperatures or something else killed it off

remains the subject of ongoing research.

And soon, the seam of coal at Cerrejon

that allowed it to be rediscovered

will disappear, too,

as the diggers move down to the next layer.

Bloch: So, on one hand, that's sad,

on the other hand, we have a big sample from this slope,

so I think we've done pretty well.

I'm pretty happy that the mine is continuing to work,

because it's going to expose all kinds of new layers,

and I'm ready to see what else is there.

So I say bring it on.

Take out the slope and open up some more,

so we can see what else is there.

Narrator: But before it goes,

there's a last twist from Cerrejon.

The fossils are starting to hint that there was something

in its lost water world to rival even titanoboa.

On this huge turtle shell are the bite marks

of truly enormous teeth.

They don't match titanoboa's dental records.

And this turtle was probably too wide

for even titanoboa to swallow.

They look like croc teeth,

but most of the croc bones so far found

aren't big enough to take on a giant turtle.

This new bone suggests another colossal predator,

nearly as big as titanoboa itself.

But this one, a crocodile.

Hastings: So we have a single vertebra

from a 13-meter individual.

Lengthwise, it would have been a little bit shorter

than a full-grown titanoboa,

but still very closely related

to the other crocodiles of this site,

based on overall morphology and shape.

Here we have a large saltwater crocodile vertebra.

This is from a 14-foot individual,

which is towards the upper bound of saltwater crocodiles.

You have the same basic elements,

this is where it articulates

with the rest of the skeleton here.

The comparison in size is just ridiculous.

This is a duck-billed dinosaur vertebra.

Same element from the body

of roughly an elephant-sized animal,

at least in weight and girth.

We're dealing with a very, very large crocodile

that was roaming around in Cerrejon.

Narrator: At 40 feet,

this is among the biggest crocodiles ever found.

This new crocodile species is on such an epic scale,

it could even give titanoboa a fight for its life.

Any snake, even the largest,

is at its most vulnerable when digesting a big meal.

Bloated by the smaller croc inside her,

titanoboa is a tempting target for a super croc.

But she has an unexpected defense mechanism.

She regurgitates her meal,

to focus all her energy on the enemy.

In the croc's death grip,

she retaliates by throwing coils around it.

Exerting a pressure of 400 pounds per square inch,

this ultimate constrictor squeezes the life

out of her biggest rival in Cerrejon's lost world.

And now, 60 million years later,

it's time for the scientists to meet her face to face.

After five years loan for research,

the Cerrejon fossils will soon be returned to Colombia.

And in their place, a new vision of titanoboa is about to emerge.

Jon Bloch and Jason head,

experts in the prehistoric world titanoboa inhabited,

are finally going to meet their discovery for real.

The life-sized model is ready to view.

Head: We've been talking about

how big this animal was for so long,

and we've marched out how long it would look,

and we've made estimations of its volume and its size,

but now we can actually see

a reconstruction sample filling the space.

Bloch: Yeah.

Head: We can really get a sense of how big this animal was.

Bloch: I hope it'll be scaled correctly,

and it'll give people an opportunity

to really stand next to this thing

and really understand, you know, how much bigger and strange

this snake would have been

than anything that is on the planet today.

Head: Yeah, that's right.

Narrator: If the model passes the scientists' scrutiny,

titanoboa will go on a world tour.

Hockley: Come on, guys.

Head: Okay.

Bloch: Oh, my God.

Wow.

Head: Wow.

Bloch: Look at that.

Holy cow.

Head: Gorgeous.

Bloch: So the coloration

you modeled after an anaconda, kind of?

Hockley: It started to blend.

Jason requested that I treat with boa constrictor patterning

and the anaconda background.

Bloch: Yeah, wow, it's amazing.

Head: It's beautiful.

Hockley: Well, thanks.

Narrator: It's extraordinary to think

that this is the actual creature derived from the single vertebra

that began this journey of discovery.

And there's one last snake secret revealed

in the way hockley has modeled the replica.

Titanoboa probably used gravity

to help move its enormous prey down its throat.

He's captured that in all its grotesque detail,

in this massive model.

Bloch: Wow.

That's incredible.

Yeah, the scale is really amazing.

Head: The scale that it's portrayed at

really brings the tremendous size of this animal home.

It's mind boggling to think of a living snake that large,

moving through an environment.

To really see it in its color,

with the skin and the muscle underneath it

and in this lifelike pose, really for the first time

in the whole time I've been working on titanoboa,

really gives me an appreciation for it as an animal.

Bloch: We're really at the point now where the snake has grown up

and we're giving away what we know,

essentially giving titanoboa to the world.

Narrator: Today, all that's left of titanoboa's lush world

is this barren landscape,

the vast Cerrejon mine.

But it's our window onto a world of super crocodiles

the size of small trucks

and turtles the size of bears.

Here among trees that are now coal,

titanoboa reigns supreme,

queen of the ancient tropical rainforest.

In her domain, she hunts down her prey.

She mates and gives birth.

She fights off other ancient monsters.

Then, one day, her reign is over.

And she disappears...

...for 60 million years.

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