Secrets of the Dead (2000–…): Season 15, Episode 6 - Graveyard of the Giant Beasts - full transcript

65 million years ago,

a giant meteor struck the earth.

Global temperatures plunged,

and a mass extinction
wiped out the dinosaurs

and changed life
on earth forever.

Little was known about
the world that emerged

after the catastrophe,

but now, a series of
remarkable discoveries...

it's a cute little skull.

Has opened a window
onto the creatures

that sprang up to take
the place of the dinosaurs.



Oh, man, look at that.

A coal mine rich with fossils...

Know what?
the preservation is amazing.

Has revealed creatures
familiar to us,

but colossal in size.

This animal essentially
became dinosaur-sized.

- You ready, bob?
- Ready.

Giant crocodiles
and enormous snakes

living side by side.

So they were probably growing

at about a foot and a half a year,

and they just kept cooking.

What were their
strengths and weaknesses?

This very, very fast maneuver



is on the order of an eye blink.

Let's go and hit it.

Oh, my gosh! Wow!

Scientific analysis will
help put together a picture

of this hostile prehistoric world...

There would be these giant
snakes preying on everything,

all over the place.

To discover the strongest predator

in this land filled with giants.

They themselves are the
only things that they fear.

The gigantic meteorite
that crashed into earth

caused a global catastrophe.

Known as the KT extinction event,

it destroyed an estimated
3/4 of all living species.

Entire ecosystems collapsed,

and the mighty dinosaurs
became extinct.

The land of giants was over,

or so it was thought.

The plant and animal
species that survived

this post-apocalyptic world

were a total mystery

until now.

Today, in Colombia, South America,

the Cerrej?n Mining Company
operates one of the largest

coal mines in the world.

They have trucks the size
of two-story houses

carrying coal cut from deep
within the earth's crust.

But with each layer
they claw away,

the company edges their way
further back in time.

In 2003, they reached
the critical layers

that were laid down more
than 10 million years

after the extinction of the dinosaurs.

What they found was stunning.

Paleontologist professor
Jonathan Bloch

rushed his research team
to Colombia.

John has spent his career
studying this period

in the earth's geological history.

It's known as the Paleocene.

He realized this could be the lost world

he'd been searching for.

John: When you open
that door into the world

58 million years ago where
no one else has looked,

you find things that
no one else has found,

so every time we come
to Cerrej?n is very exciting

because after coming
for well over a decade,

every time we come,
we find something new.

Oh, man,

look at that.

Pretty cool.

The scale is incredible.

I mean, there's so much
exposure of rock here.

Hundreds of fossilized leaves were

scattered in the layer,
indicating the land

during this time was
dramatically different

from the cretaceous
world of the dinosaurs.

John: See that?

Yeah, this is a leaf layer here.

There's a leaf right here.

We see the first evidence of avocado

and ginger and chocolate and beans.

You can see enough
to see that this is part

of a forest that's very warm.

The size of the leaves that we find

in these layers tells
us it's also very wet,

so this is consistent
with a tropical forest.

This is the stuff I was talking about,

and it's up there, too.

The impact of the meteor gave rise

to an entirely new type of rainforest.

John and his team wondered
what animals might have lived

in this swampy, humid environment.

John: We came here to
look for fossil animals,

but when you're going to a place
where no one has found fossils before,

and you know you're taking kind
of a gamble, it can be weeks

before you find anything,
if you find anything.

But within maybe 10 or 15 minutes,

we found the first bones at Cerrej?n.

Oh, check this out.

I don't know. What's that?

What they found was beyond anything

they could have imagined.

- Oh, that's really cool.
- Yep.

The place was rich with
fossils of ancient species,

but there was something
noticeably different about them...

You see that?

Their size.

This was a land of giants.

John: We're lucky to have found this.

This is a big turtle.

Carbonemys cofrinii

was the largest freshwater
turtle of its time.

Today, freshwater turtles rarely
exceed two feet in length,

but this enormous creature was
the size of a family car,

with a skull as large as a football.

More intriguing were
the signs that this giant

may have been small prey
to a much larger predator.

John: The shell of carbonemys,
shows us many things

about its size, but another
really interesting feature

are these puncture marks.

You can see them here, there,
and throughout the shell.

From these puncture marks,
we can see that the turtle

was probably bit many times
throughout its life.

The fact that we can see
so many bite marks

on the carapace might tell us
one of the reasons why

these sideneck turtles would have had

so much thicker shells
than what we see today.

These puncture marks
indicate something

much larger was lurking
in the swamps, with a bite

so powerful, it could pierce
a thick, armored shell.

The scientists quickly found evidence

of the species responsible
for the attacks...

What is this?

But these were juveniles.

It's a cute little skull.

Ah, yeah, look at that.

John: We didn't know
what they were at first.

It became pretty clear
after a day of collecting

that we had fossil
crocodile relatives.

What you're looking at
here are the two eyes,

and then two holes
on the top of the skull.

Didn't make it to maturity.

The mine was crawling
with ancient crocodiles.

Each piece of fossilized
bone was carefully packed

and shipped back
to John's lab in Florida.

- See that?
- Ah, yeah.

There, Dr. Alex Hastings,

a member of John's team,
was racing to catalog

all the finds as they poured
into the lab from Colombia.

Alex: In the beginning,
dozens and dozens

and then hundreds more of
these fossils were coming in,

and getting a chance
to unwrap these things

and kind of start piecing
everything together was great.

The team found different
crocodilian species,

including the culprit responsible
for attacking the turtles.

Alex: This is the short-snouted
one, or the turtle chomper.

Several large turtle shells,
from the Cerrej?n site

that have marks that fit very well

with the teeth of this
individual crocodile.

But the largest croc
they found was a species

called acherontisuchus.

It was no bigger than today's crocs;

a surprise, given how large
the snakes and turtles were.

Alex: Acherontisuchus
could have gotten

to somewhere between 15 and 21 feet.

Now, this is really on the upper
bound of crocodilians today.

Given the extent of the wounds
found on the giant turtle,

there was the suspicion that
somewhere in the Cerrej?n mine,

there lurked an even larger predator.

Crocodiles are as old as the dinosaurs.

The first evolved around
200 million years ago,

at the start of the Jurassic Era,

and 145 million years before
the period John studies.

The largest crocodile that ever lived

was called sarcosuchus.

Up to 40 feet in length,

this 8-ton monster held its own

in the age of the dinosaurs.

So far,

Cerrej?n seemed to suggest
that crocodiles of this size

died out with tyrannosaurus rex.

John's team soon found
another colossal bone,

but was it from a crocodile

or some other giant monster?

John: There were so many bones
to pick up that we didn't always

identify everything properly
that we collected.

Picking up a bone, and I remember
talking to a student about it

at that time, and we looked at it and
we weren't exactly sure what it was.

So I wrapped it up
in our paper and tape

and put a field number on it
and wrote, "crocodile?"

Alex: Late at night, I was just
kind of unraveling these things.

Most of them were crocodilians, but
there were a handful of bones there

that were clearly not any crocodilian.

The whole structure of the
vertebra was completely different.

Alex and a fellow student recognized

that although it was the size
of a crocodile vertebra,

it actually belonged to a snake.

Alex: Not only, you know,
a really big snake,

but being bigger than
any snake we knew of,

and we immediately started
pulling out skeletons of anacondas

and pythons and finding anything
we could about giant snakes,

and every single thing
we were finding

was smaller than what we
were looking at.

This part right here.

Anacondas are the largest
snakes alive today,

but their vertebrae are dwarfed

when placed next to that
of the Cerrej?n monster.

John: We realized that the bones
that we had in our hands were

much larger than anything that
had ever been described before;

in fact, so much larger that,

I had all kinds of wild ideas
right away about how large

that snake would have been,
and so that's when I contacted

the world's expert in calculating
body size in the largest fossil snakes.

That scientist was Dr. Jason Head,

and what he was about to see

would redefine the
concept of the giant snake.

Jason: John video-chatted
me one day and said,

"I have a giant snake. You have
to see this. It's amazing."

And I said, "you know",

"I?ve seen snakes that are

supposed to be giant snakes,
and they never turn out to be

as big as you say they're going to be,
so sure, you know, show me the snake."

And then he came back holding

a giant vertebra and he put
it right up on the camera,

and at that point I got very excited,

and I bought a plane ticket
and went down there.

John: So when I came in the
next morning, I ran into Jason

and he looked at me with
kind of wild eyes and said

"this animal is going to
reset everything we know

about what it truly means
to be a giant snake."

The sheer size of the snake
was hard to comprehend.

Jason: We started to get body size
estimates that were really astounding.

I was really worried that
we were doing the math wrong,

and so we went back and we did
the math over and over again,

and every time, it kept giving us
the same, massive length.

So after a while, I simply
had to accept the fact

that this animal was
almost 50 feet long.

Weighing more than a ton,

this giant snake was 5 times
bigger than the largest alive today.

They named this new python titanoboa.

When they published
their findings in 2009,

the discovery of the snake made
headlines around the world.

Little did they know that
there was another monster

lurking out there,
waiting to be discovered.

Fossils in the coal mines
of Cerrej?n revealed

that giant aquatic reptiles
filled the ecological void

left by the dinosaurs.

What was it about these creatures
that allowed them to thrive?

In the extreme winter that
followed the meteor impact,

global temperatures plummeted.

Turtles, snakes, and crocodiles
were able to scavenge and gorge

on the dead carcasses and then
go for months without food.

Being cold-blooded
gave them an advantage,

allowing them to sit out the disaster.

Eventually, nature found a way
to restore its delicate balance

into a world that was very different

from the one their
ancestors had left behind.

John: It took a while for
that ecosystem to recover

from that extinction event,

and what we see here in this forest

is similar in some ways
to what we find in Cerrej?n.

And as temperatures rose again,

a 43-foot-long snake dominated
the swampy world.

Jason: It probably almost
never left the water.

I think this animal would have had
a hard time breathing on land.

Just hanging around on the bottom,
for the most part, waiting for food.

I think it would be very hard
to have killed titanoboa.

Snakes are not easy to kill,
actually, in general.

They're pretty rugged animals,

they're pretty tough, and
when they're 43 feet long,

they're probably extremely hard to kill.

Our hypothesis going forward
about the ecology of Cerrej?n

is that titanoboa is the apex predator.

For years, scientists believed

titanoboa was the apex predator
of the Cerrej?n swamp,

until Jonathan Bloch called on one
of his top graduate students for help.

Aldo Rinc?n's expert eye scanned
the mine for more huge bones,

and it wasn't long before he found one.

It wasn't a snake bone,
but it was large enough

to have existed during
the era of the dinosaurs.

Yeah, we need to try to get
out of this channel,

there or to where Jason...

Yeah, you're right. It definitely
starts looking better over here.

My first guess, that's, I mean,
it looks like a dinosaur.

Yeah, maybe in some of these
channels or something,

it might stand a chance.

But we knew that there are
no dinosaurs in here, so,

I mean, that was pretty exciting, but at
the same time, it was pretty confusing.

Could it be that Aldo had
unearthed the beast responsible

for attacking the giant turtles?

In Florida, Alex Hastings got a
look at the newly discovered bone

and immediately realized
it belonged to a crocodile

and could rewrite history.

Alex: And it's just amazing
to kind of unravel this thing

and have something that you know
is way larger than anything else,

but it's frustrating because it was
just this kind of tantalizing clue

that there is this massive,
massive crocodilian there.

So, we know at least, at least one

of these guys got to
be really, really big.

Alex suspected this bone was evidence

that giant crocodiles were not
destroyed by the KT event,

but survived into the new era.

First, he needed to know
more about this bone.

Where precisely did it fit
into the crocodile skeleton?

And did it belong to
an adult or a juvenile?

To find out, he headed to
the University of Chicago,

home to America?s only
fossils of sarcosuchus,

the prehistoric crocodile
from the dinosaur era,

still believed to be the
largest to have existed.

The university is also
home to Paul Sereno,

a leading expert on
these prehistoric giants.

Paul: Sarcosuchus is the best known

of the giant crocodilians.

In terms of feet, we're
talking about 40 feet long.

Seeing the fossil for the first time,

professor Sereno
realized the Cerrej?n croc

could be on a scale to
match the sarcosuchus.

Big for a croc. Very big.

It's a great specimen.

It looks like it's
getting close to maturity.

You know, with all the parts,
it would be, I suppose,

about that tall and have
a vertebra about that wide.

Yeah, it definitely
extends quite a bit longer.

I got a 12-foot alligator upstairs
that looks tiny compared to this.

Awesome, yeah. Yeah.

Paul: This giant crocodile
is really fantastic.

It's a window onto a time that we
have very little information about.

So this is really of great interest
that there might be a lineage

that also survived the KT
boundary that we don't know about.

Alex: This is from a dorsal series.

I?m thinking just kind of
little back behind the neck,

somewhere in the, the rib cage area.

Paul: The vertebra from
Colombia is a large croc.

How large? I think we need to determine.

We'll take this to the scanner,
and it'll be interesting to compare.

- Yeah.
- Yeah.

The first step was to
scan the partial bone

to get an accurate picture of the
precise shape of the original vertebra.

The vertebrae vary in size and shape.

By making a direct comparison with bones

from a similar position in the spine,

they can predict the exact size
of the Cerrej?n crocodile.

Alex: The reason we're doing this
is to help us understand better

where in the vertebral column,
where in the backbone,

this one fossil from Colombia fits in.

So it's important to have something
that's very large to compare to

to get a more accurate idea
how big the fossil one was.

The scan also allowed them
to see inside the bone,

where the internal structure and density
would tell them the age of the creature,

whether it belonged to a small
juvenile or a fully grown adult.

- Great. Well, let's get these scanned.
- Yeah.

Alex, voice-over:
Seeing Paul?s reaction to it,

knowing that he's already
very familiar with sarcosuchus,

is kind of confirming that
we know we're definitely

in that really, really big
croc territory.

The early signs suggest this
could be a new giant croc species.

What allowed these creatures to grow

to such a gargantuan size?

Scientists found a clue
not in animal fossils,

but in those left by plants.

Jason: This leaf here has, is what's
called a smooth or complete-margin leaf,

and it's got a very continuous
outer margin to the shape.

And this is a serrated,
or jagged-margin tooth.

There, it's got serrations
almost like a knife.

Most of the fossil leaves in
Cerrej?n were smooth-edged,

allowing them to retain
moisture in a hot environment.

The leaves confirmed Jason?s suspicions

that Cerrej?n was around 4 degrees
hotter than rainforests today.

Jason: It would have been
constantly raining and very wet,

incredibly hot and humid all the time.

Cold-blooded animals like snakes rely

on external factors to
set their body temperature.

In warm environments, they're
able to expend more energy.

In the heat of the swamps,
titanoboa would have been

hunting and eating its way
to its gigantic size.

But what about the ancient crocs?

Dr. Greg Erickson is one of the
world's leading experts in crocodilians.

This aggressive alligator was
culled to protect the public,

but beneath its skin lays a clue
to its ancestor's great size.

Greg: So this is essentially
a very armored animal,

but there's more to these
osteoderms than meets the eye.

What you would see, if we
cleaned the skin off of this,

is something like this,
and this is an osteoderm.

The hard, bony osteoderms

protect the crocodile's
vulnerable back,

but they also contain hidden information
about the growth rate of the animal.

Greg: These animals lay down
annual growth lines in their bones,

and the osteoderms preserve them.

It's pretty much like the
growth rings in a tree.

In the case of giant crocodilians,

it's possible to figure out
how they became giants.

Dr. Erickson carefully
slices off a tiny sliver

from the alligator's osteoderm.

Voila. See how we did.

Erickson, voice-over:
Well, we've got our osteoderm

under a microscope, and lo and behold,

we can see the annual growth lines.

This last growth line was the one
that was laid down just before it died.

Its younger growth lines
are back here,

and they're much broader,
and we would expect that.

That's when an animal's young,

essentially its teenage years
and growing like crazy.

There's 15, maybe even 20
that I can see right there.

These animals usually mature
between 12 and 15 years of age,

and then they start
plateauing their growth.

And you can see how it, how the growth
lines start getting tighter and tighter

towards the periphery, so its
growth was slowing at that point.

This mature alligator
has 15 growth rings,

one for each year before
it reached adulthood.

However, when Greg compares
this to an osteoderm

from the giant croc, sarcosuchus,

there is a striking difference.

Greg: The difference is
this osteoderm has 55 to 60

of these growth bands
packed in there, so,

this animal essentially
became dinosaur-sized

instead of plateauing
at, say, 20 years.

As you might see in American alligator,

these animals plateau their growth
at maybe 40, 45 years of age.

And so they were probably growing
at about a foot and a half a year,

and they just kept cooking.

The secret to crocodilian giantism is

simply prolonging
the timing to maturity.

So it's likely that the
Cerrej?n croc was able

to delay its maturity,
allowing it to grow

to a fearsome size,

but exactly how big?

You want to run those
vertebrae through first?

Alex: All right. Let's do this.

The scan will generate
3-dimensional images

and allow the scientists
to see inside these giant relics

for the very first time.

Paul: Looks like a great scan.
Alex: Yeah.

He beautiful when it's done. Good.

Wow! That's cool.

Paul: You, you've got the form

and the internal
structure of the bone now,

so you can make a comparison.

The shape will confirm
where the bone sat

in the croc's spine, and the
density will help determine

whether it's a fully grown adult

or just a juvenile with a lot
of growing still to do.

- So much detail.
- Yeah.

It's going to be
fantastic to go through.

Now, that could be a preservation
thing in the Cerrej?n one,

so maybe it's just been more in-filled

with sediment in the
fossilization process.

Great to see the CT scan.
The surfaces look fantastic.

There will be a lot of numbers to crunch

to really get the answer
for how big exactly it was.

Yeah, let's see, let's
go through that...

the one, the Cerrej?n specimen.

- This one?
- Yeah.

This new bone suggests

that the prehistoric swamps of Cerrej?n

were a world unlike any other,

a unique environment
filled with reptiles

of an astonishing scale,

and one where a giant
crocodile and colossal snake

both inhabit the same ecosystem.

All the evidence indicates
that whenever snakes

and crocodiles hunt
in the same quarters,

it ends in conflict.

The Florida everglades provide
a wet and humid habitat

where descendants
of the Cerrej?n giants live

and hunt in the same territory,

the indigenous American alligator

and the invasive Burmese python.

Research ecologist Kristen Hart
is charged with capturing

the disruptive pest using a GPS
and radio tracking system.

Kristen, voice-over:
We know for a fact these

Burmese pythons came here
because of the pet trade.

They were, nice pets for people,

then they got really big
really fast and,

they were too much
to handle, so instead of

putting a pet down, they may
have come and released it

in a nice environment
like the everglades.

We're very close to the animal.

Kristen, voice-over: So the
python is a damaging critter

for the everglades because it
does compete with the alligator

as a top consumer in the food chain.

In these ideal conditions,

the snake population has exploded,

leading to a shortage of food

and violent clashes.

Kristen?s radio transmitter's
uncovered evidence

that the two predators
are turning on each other.

We were tracking one
of our radio-tagged pythons

and the signal was clearly
in the alligator

'cause as the alligator started
to move away from us,

the signal got weaker and weaker
as the alligator got further away,

so we know from that instance that the
alligator actually consumed the python.

We have definite evidence
from stomach-content analyses

that pythons do consume alligators.

I don't know of too many other
places where you have crocodilians

and large constrictors
consuming each other.

Today, sightings of hungry pythons

taking on much larger
alligators are not uncommon.

This battle between
a large Burmese python

and a juvenile alligator
was captured on video.

It took the python more than 3 hours

to constrict and eat the alligator.

And this fossil reveals
the same battle raged

millions of years ago.

It's hard to see, but nestling

in the stomach of this fossil snake

is a baby crocodile.

It is clear that in the murky swamps

of the Cerrej?n, the giant
snake and the mega croc

would inevitably
have come into conflict,

but which one would triumph?

By looking at their living relatives,

we can piece together
how these two killers

use their impressive array of weapons.

Snake expert David Penning
demonstrates

one of the snake's formidable tools?

the thermal equivalent of vision.

David: So a snake has
a whole other world

that it sees than what we do.

So not only can they see
something visually,

they can also pick up
the heat signature of it.

This super sense allows some snakes

to see their prey, literally,
in a different light.

David is going to demonstrate how.

David: So today we're going
to try a thermal experiment.

Many boas and pythons have
external pits and nerve endings

in their head that allow them to actually
perceive infrared or thermal energy.

So we're going to use
a snake that has pits.

I?m actually going to cover her so
that she doesn't feel like exploring.

So what we have here are two different
gloves with two different temperatures.

This is a glove filled with hot water,

and this is a glove
filled with cold water.

So we can't see the difference. She can.

She has an infrared sensing system

that can differentiate
between temperatures,

so this snake will be presented
with two gloves that look alike

and are moving similarly but are
very different in temperature.

It's in a low light situation,
so snakes are more likely

going to be relying on their
infrared sensing capacities

to make a choice between
which object to strike at.

We don't have this system. She does.

She's gonna be perceiving
infrared energy we can't.

Chances are it'll make the
decision for the hot glove.

And there she goes, and when
offered these two gloves,

she's orienting towards
and striking at the warm one.

Using its heat sensors,
the snake can detect its prey

without even seeing it.

Then it's only a matter of seconds
before it launches its deadly strike.

David: So in many boas and
pythons, they have heat-sensing pits

in their labial scales
around their lips,

and, what those are, are
extensions of the trigeminal nerve.

The nerve actually comes out and
is in the base of those pits.

So those are free nerve endings
that interpret infrared heat.

They're constantly? you can think
of it almost like a Geiger counter.

They're constantly ticking,
so the snake is experiencing

a nerve impulse? about 13 to 30
times a second, the snake?

the nerves are firing,
but when an infrared image

or a hot object is put in front of it,

it starts to increase, and so it
sends a signal back to the brain

that allows them to see
a thermal image of their prey.

And just like boas today,

titanoboa would have used
the same capabilities to hunt.

This super sense made it
an expert at ambushing prey.

But the croc is equipped with
its own unique tracking device.

Dr. Erickson understands what
makes these carnivorous beings

so skilled at pursuing their quarry.

Greg: The architecture of a
crocodilian head is just amazing

how sophisticated this is,

just a remarkable killing machine.

These killing machines
have an incredible tool?

dome pressure sensors,
thousands of tiny dots

sprinkled around the mouth
that act as built-in radar,

directing the beast toward its target.

Say there was an animal splashing
in the water over there.

The pressure waves from the water
would hit the face of this animal.

It would go down through
the dome pressure sensors,

and basically register
with the brain that,

"hey, there's something
going on over here."

This animal would
make its way over there.

So it's really a
remarkable sensing device.

These sensors allow the crocodile to sit

stealthily beneath the water's surface

before attacking its unsuspecting prey.

Greg: Dome pressure sensors are
features found only in crocodilians.

The architecture of those structures

are completely unique
to the animal kingdom.

These animals, from a sensory
standpoint, they've got it all.

Back in Louisiana,
David Penning is trying

to measure something that has
never been measured before.

He's going to calculate
the strike speed of titanoboa.

David: We don't have a snake
alive today the size of titanoboa.

What we do have are snakes
of different sizes alive today.

We estimate what titanoboa can do based
on what living snakes today can do.

Snakes are incredibly
difficult to see in the wild.

They move slowly toward their prey,

getting as close as
possible before striking.

When they do, as David demonstrates with
a dead mouse, it's with ferocious speed.

David: The strike that we just
saw here by this red-tailed boa

was probably on the order
of 50 to 100 milliseconds.

So this snake starts a strike
and comes in contact with the prey

before the prey even has
the ability to send a signal

saying, "something might be a threat."

Many snakes have the ability to
reach their target before their target

is even aware of the fact
that something just happened.

Like its modern descendants,
titanoboa was a constrictor,

and it would have used the same
tactics to surprise its prey.

David: It was likely striking at prey
from only about a half a meter away.

That's because it's waiting
for prey to get close,

and half a meter is a
considerable distance,

but not when you're something
the size of titanoboa.

Having amassed a comprehensive
data set of size versus speed,

David is now able to speculate how
fast titanoboa could strike its prey.

David: 0.1 to 0.2 seconds.

0.2 seconds is on the order
of an eye blink.

So this is still a
very, very fast maneuver.

These values are within the range
of what we would expect

from smaller snakes, but that
actually makes it more impressive,

considering the size of what this
animal had to move towards a prey item.

Titanoboa accelerated, on average,
150 meters per second squared

during their strikes.

Humans pass out at about
50 meters per second squared.

This incredible speed exerts a force

15 times greater than gravity.

If the human body
accelerated at this speed,

we would almost certainly
suffer brain damage.

So we're talking about impact
pressures similar to what we see

in impacts with bullets shot.

The strike speed of this giant
snake is truly terrifying,

but the giant crocodile
was hardly slow.

The secret behind the crocodile's
attack speed was its muscular tail

that propelled it towards its prey.

Greg: Crocodilians swim sinuously,

moving their tail back and forth,

but if they need burst speed,
they can do it very powerfully.

This massive tail is the secret

to the incredible acceleration
these animals can do.

It's a, you know, this is what
creates the propulsion.

You know, some of them can
leap out of the water.

Most crocodilians can seize prey within
about 2/3 of their total body length.

So the bigger the crocodile,
the more powerful its acceleration,

up to 40 feet per second,

or its full body length
in the blink of an eye,

but stealth is just the beginning.

Once the prey is caught,
the two predators use

very different techniques to kill.

The crocodile's greatest
weapon is its powerful jaws.

How can bite force be estimated

for an animal that lived
58 million years ago?

One of Dr. Erickson?s ongoing
studies is the relationship

between a crocodile's size
and the power of its bite.

He carries out his research at
an alligator sanctuary in Alabama.

Here, well-fed gators are used
to interacting with people.

We'll start with him.

I think he'll give us a good bite.

Greg: Crocodilians have been, you know,
the guardians of the waterland interface

for 85 million years, and
the secrets to their success,

or a lot of it, comes from
their feeding abilities.

Yeah. We're gonna need,
boy, 6, 7, people.

Yep.

It?s routine procedure for these gators

yet still extraordinarily
dangerous for the team.

Think we can make it happen?

Greg: It's gonna take quite a few?

a small army of handlers to get
that animal over to here

so we can test it, so
we'll see how it goes.

Let me get the rope on him,

see what kind of mood he's in.

You got any smaller ones?

We want to get this strap right
at the back of the head,

trying to get the head pinned down

and then, of course,
do the rest of them.

Hey, come here. Up, up, up here.

Up here. Come on.

All right. Now pull it. You got him?

Stay over there.
OK. Got him? All right.

- Get the ropes.
- Get the ropes.

- Get slack.
- Give me some slack. There you go.

Greg: Right. Let him back up a
little bit. Then we'll do it again.

All right. Now get ready.

All right. Cool.

Get right. All right. Let's get him.

All right. Hold?

Yeah. Get on the head.

Got a foot.

But even experienced gator handlers

can be caught off guard
by sheer brute strength.

The last one to go is this?

Oh! Oh, you OK there?

Yep. I?m good. She
caught me off balance.

Greg: What I?ll do is,
I?ll insert this flat plate

into the mouth of the alligator.

As soon as this plate touches the teeth,

the animal is gonna slam it.

It elicits a very, very forceful bit.

As that plate's compressed, it's
gonna give us an electrical readout

that tells us how much force was
involved during that particular bite.

OK. OK. Good boy.

Ready? Come on.

Come on now. There's a good one.

Holy? 2,431 pounds.

Oh!

Wow, awesome. Wow,

over a ton of bite force.

Pretty cool, wasn't it?

That was awesome.

Greg: What these animals do is,
they sink their teeth

into the hide of large game
and get a purchase on it.

Then they work the animal
out into the water,

use their great mass, and just
submerge the animal and drown them.

If that animal starts struggling
and is getting out of the jaws,

they'll reassert their bite again.

The real secret's right
there, those muscles,

the pterygoid muscles, and
you'll see those contract.

This is really the engine
behind this creature.

60% of the bite force
comes from right here.

it's not? that's not the neck.

That's actually jaw muscles that
are billowing out at the back.

I think this mimics, prey that
are struggling in their mouth,

that they want to reassert their bites.

Let's see if it bites again here.

There it is, nice clench.

That was 1,544 pounds,

and that's without slamming the jaws.

That's just from a dead start.

It's like a high-horsepower
engine or something.

It was, "boom!"

It's gonna pop out.

All right.

Greg?s study proves the power

of a crocodile's bite is
proportional to its size.

Wow. Really hammered it.

Greg: He's just being as
cooperative as he's gonna get.

This alligator's 11'6", but it
felt like a 13'5", I?ll tell you.

Like, it gave us a heck of a run.

I liken this to being kind of
like bull riding for scientists.

All right.

Once Alex Hastings gives Greg an accurate
size for the Cerrej?n crocodile...

Good boy.

He will then be able to estimate
the power in the beast's bite...

All right.

But titanoboa was far from defenseless.

As a constrictor, it was able
to exert crushing force.

Just how strong was
our prehistoric giant?

David Penning has spent years studying
the constriction strength of snakes.

Now he's going to apply
the same expert analysis

to estimate titanoboa's crushing power.

David: We are going to be
testing 400 to 500 snakes

to predict what titanoboa could've done.

That's the largest data set on
constriction performance on the planet.

By fixing sensors to the
snake's meal of a dead rabbit,

David will be able to measure
how much pressure

this comparatively small
constrictor can exert.

We are recording.

David: 3 PSI.

3.2. Yeah. She's
dropping off a little bit.

That pressure is in the range necessary

to kill a prey animal
by circulatory arrest.

3.2 pounds per square inch

is more than enough pressure
to kill even larger animals,

but how does that compare to the
pressure titanoboa could apply?

David: She is probably
15 feet and 3 or 4 inches.

So from that length,
if we know that she's 15 feet

and titanoboa could get upwards
into the 30- and 40-foot range

and she squeezes with
a certain pressure?

we know what smaller snakes,
other snakes her size can squeeze?

we can infer what
titanoboa could've done.

Armed with the results
of the constriction tests,

David reveals the unparalleled power

of the snake's gigantic ancestor.

David: Titanoboa likely squeezed
with a constriction pressure

ranging from 50 to 250
pounds per square inch.

That's 250 pounds of pressure exerted

on every inch of contact
with the prey's body,

but when David estimates
the total pressure,

the potential force is truly terrifying.

David: The high end of the estimates,

we're looking at 1.3
million pounds of force.

A tank weighs about 150,000 pounds,

and so we're almost at order of magnitude
greater than the weight of a tank.

That is just, frankly, not survivable.

But David Penning's research
has thrown up another surprise

that casts light on precisely
how titanoboa killed its prey.

It has long been believed that

snakes constrict their
prey until they suffocate,

but David?s latest data suggests
the kill is far more efficient.

By studying the internal
damage to the prey,

David has discovered that an
entirely different phenomenon

kills the animal.

The force of constriction
induces what's called a redout,

what animals experience
when the brain is under

a massive amount of physical pressure.

David: We see these effects in prey,

so not only is their heart
having problems pumping blood,

you now have approximately
half or a third of your blood

above that coil, and pressure's
being pushed here.

That fluid has to go somewhere,
and that somewhere is in your brain.

Applying the equivalent pressure
of several military tanks

floods the animal's brain with blood.

David: It's forcing blood
towards the only exit,

which are the eyes,
the nose, and the mouth.

So when something like a
crocodile is being constricted,

they literally see red
before passing out.

the force exerted by titanoboa

would most likely have induced a
brain hemorrhage in its victims.

David: I?ve checked it several times.

If titanoboa squeezed with
the pressures that we predict,

I don't think there's
any animal on the planet

that would have survived
something like that.

It's absolutely incredible.

At the University of
Chicago, Alex Hastings

finally has the details he needs

to estimate the size and
age of the crocodile fossil.

The first surprise is that the
bone was not from the lower back

near the tail, but is near the neck,

but was it a fully grown adult
or a developing juvenile?

Alex: The CT scans were amazing.

The level of detail is unbelievable.

You kind of see a little more
of a spongy kind of texture

in juvenile bones that you see a much
more solid, firm texture in the adults.

This is another kind
of indicator that fossil

from Cerrej?n is likely
an adult individual.

The Cerrej?n crocodile
was a young adult,

but, more importantly,
it was of a size to match

the croc from the
dinosaur era, sarcosuchus.

Alex: The Cerrej?n croc came out
to be about 8.63 meters,

which is about 28 feet.

That is an enormous croc.

It's bigger than any crocodile
that we have alive today.

This behemoth of the swamps was
almost 30 feet long, 3 feet high,

and weighed 3 tons, proof at last

that the giant crocodilians

did survive the catastrophe
that wiped out the dinosaurs.

These two colossal
reptiles achieved a scale

not seen since the days of the dinosaur.

Can we come up there?

Now that we know
how large the croc was,

Dr. Greg Erickson can finally estimate
the power of its monstrous bite.

It is of a magnitude
equal to that of a T. Rex.

Greg: We're talking about
15,000-pound bite force,

or we're talking about twice what
any living crocodile could do.

About there.

To demonstrate this crushing power,

they will use this skull of an adult cow

to see how it might fare in an attack.

- Well, yeah, pretty sciencey.
- Yeah.

Greg, voice-over: I suspect that
a crocodile that can generate

15,000 pounds of bite force
could pretty much crush

just about any animal it got a hold of.

We've got a cattle skull here,

and we're gonna take a
mechanical loading frame.

This is a device that
engineers use to test

the strength of
structures and materials.

We'll also be taking
the data, and we'll get

a force displacement curve,
and from that, we can see

when the structure started failing.

Oh, it's still hitting.
It's hitting on this side.

We've got to watch it tilting.

They're going to exert 15,000 pounds
of pressure on this cow's skull,

second only to an
elephant's skull in strength.

Greg: Hold it. Yeah. I think it went.

So we're ready to conduct our test.

We'll see what happens.

- You ready, bob?
- Ready.

OK. Let's go and hit it.

Oh, my gosh, wow!

Oh, just blew it up, amazing. Wow.

How much force?

3,000 pounds.

The skull is obliterated
when just a fraction

of the ancient croc's
ferocious power is applied.

I feel like I?m crawling
through the wreckage here.

So that was a demonstration
of just 3,000 pounds of force.

So? imagine 5 times that.

I mean, it? this thing was one
of the ultimate killing machines.

Oh, my gosh, wow!

We now know the croc's bite
force was of a magnitude

not seen since the age of dinosaurs.

Greg: I don't think any animal

in this creature's realm was safe.

I mean, this is a dangerous creature.

Oh, my goodness.

Bob: Yeah. that definitely
broke that thing.

That's bite force.

By studying the attack capabilities
of the smaller descendents

of these prehistoric giants,
we've been able to piece together

the incredible powers
of these fearsome predators.

Juveniles would always be
vulnerable to other species,

but when two adults went head to head,

which would become the apex predator?

Paul: It's a question of who's
gonna have the upper hand.

Would the snake be able
to coil around and/or engulf

the crocodile before
it would have a chance?

With a stranglehold more crushing than
the weight of several military tanks,

titanoboa's size alone might
have given it the advantage...

Jason: There's not a single
animal that could've survived

being constricted by those coils.

But if the crocodile struck first,

a bite force of 15,000
pounds per square inch

would be more than
enough to kill anything.

Oh, my gosh, wow!

Paul: If you are in the territory
of battle of a crocodilian,

you don't stand a chance.

In the end, it isn't how the
creatures kill that settles the debate.

It's how they eat.

Jason: Snakes can't actually
purchase prey with arms,

and they don't chew.

They don't rip their prey apart
and chew pieces of it.

They're basically walking
their body over the prey.

So those lower jaws can swing out,

and there's a big mass of soft
tissue that can actually expand

and create a massive gape.

So for a titanoboa with a skull,
say, about this big,

a gape would've exceeded
two meters in total size,

big enough to swallow any of the
other vertebrates we find at Cerrej?n.

This ability allows this
12-foot Florida python

to consume prey that would have
been too large for other predators,

but there are limits
to what it could digest.

David: The question becomes, could
it have fit it in its stomach,

and from the data that we have today,

the largest prey that something
like titanoboa would have been taking

was 60% of its own body mass.

Would the Cerrej?n croc's size
have ruptured the snake's belly?

It's this detail that
decides the outcome,

for, despite titanoboa's larger size,

the adult croc was
too big for the snake.

Crocodiles, however, do not
need to swallow their prey whole.

They rip it into pieces.

In the 6 years since
its fossil was discovered,

scientists through titanoboa dominated
this little-known era exclusively,

but this land of giants
has a new ruler,

a crocodile with the size
and force to outrank its rival.

Cerrej?n has a new apex predator.

Jason: To find something that amazing

that both tells us so much
about the natural world,

it is a constant reminder to me

of just what we don't know
about the planet.

Jonathan: Who knows
what's still to be found

in these different types
of environment?

I think we're right at the
beginning of understanding.

This program is available on DVD.

or call 1-800-play-PBS.