All language subtitles for T-Rex.An.Evolutionary.Journey.2016.WEBRip.Amazon-English

[narrator]
Seventy million years ago,
the mightiest dinosaur

that ever lived,
roamed the earth.

Its name was Tyrannosaurus Rex.

[roars]

[growls]

It was 13 meters long,
and weighed six tons.

This awesomely creature,
was king, of the dinosaurs.

Much about T-Rex has been
shrouded in mystery.

Now with modern technology, a clear picture is taking shape.

Remarkable physical capabilities
that defy conventional wisdom.

[powerful music]

An advanced brain,
and intellect, for hunting.

We look at their brain
and wonder whether that

enlarged cerebrum may have
actually had the capacity,

to be involved in, sort of
a coordinated

group hunting effort.

[narrator]
In addition, new fossil finds
from around the world,

are revealing the origins
of this enormous predator.

It turns out, that T-Rex's
ancestors were actually small,

and frail.

They weren't, you know,
the big bears, with the big

lions, with the big tigers,
at the top of the food chain.

They were something much
smaller, much weaker.

[narrator]
Somehow Tyrannosaurus

transformed
from small creatures,

threatened by their enemies,
into the most powerful

dinosaurs of them all.

Starting with the very
earliest ancestors,

we'll explore an amazing tale
of evolution.

Siblings on a journey in search of new lands,

they cross paths with
a fearsome carnivore.

Which will reign supreme?

The king of kings,
Tyrannosaurus Rex.

This is a story of 100 million
years of remarkable evolution.

The first Tyrannosaurus fossils were discovered

in the United States,
in the early 20th century.

[soft music]

The dinosaur's monstrous
appearance inspired its name,

Tyrannosaurus Rex.

Tyrant, lizard king, or T-Rex,
for short.

For more than a century,
scientists have been working

to piece together
T-Rex's evolution.

Stephen Brusatte, is one
of the top researchers

in the field.

So everybody in the world,
has heard of T-Rex.

But for a long time, there have
been some big mysteries,

about where T-Rex came from,
how it evolved,

how it got so big.

And these have been mysteries
for many decades.

But finally, over the last
15 years, people all over

the world have been finding
older, smaller, more primitive

Tyrannosaurus, that tell us,
where the big ones came from.

[upbeat music]

[narrator]
Scientists are zeroing in,
on T-Rex's roots.

[growling]

They've determined,
that its earliest ancestors

first emerged far
from North America.

This is the Junggar basin,
in the Xinjiang Uyghur,

autonomous region of China.

Now dry, this landscape was once home to many different types

of dinosaurs.

In recent years, excavations
have unearthed a wide variety

of fossils.

Xu Xing, has led some
of these digs.

Inside a 160 million year old
soil strata,

they found a completely new,
meat eating dinosaur.

A crown like appendage,
on its head inspired its name.

Guanlong, or "crown lizard".

Xu and his team, conducted
a detailed analysis

of the teeth, and bones.

They determined that Guanlong,
was T-Rex's ancestor.

[mysterious music]

[dinosaur]
Ahh, there they are.

[narrator]
A group of Guanlong siblings,
they're on the hunt.

One takes off, perhaps
he's the oldest.

He closes in on his prey,

but he's no match.

At this point in time,
the Guanlong was just

three meters.

Dwarfed by the thirteen
meter long T-Rex.

It weighed only 75kg, 1/80th
of the weight,

of its massive cousin.

The very oldest Tyrannosaurus
were much, much different,

much smaller, but they didn't
have anywhere near

the firepower of a T-Rex.

They were kind of like,
you know, cats or dogs,

kind of that type of animal.

They weren't you know,

the big bears, or the big lions,
or the big tigers at the top

of the food chain.

[narrator]
How did such a small,
and relatively weak creature,

eventually lead to T-Rex?

The largest dinosaur
of them all?

[growling]

The story of Tyrannosaurus,
is really a story

about evolution.
And one of the things

that it tells us, is that
evolution is unpredictable.

When those very first
Tyrannosaurs like Guanlong,

entered the scene,
175 million years ago,

you never would have thought
that they would ultimately

evolve, into giant monstrous
animals like T-Rex.

But that's what happened.

How were they able to survive
for so long, for 80 million

years, as these small,
human sized carnivores?

And then maybe the biggest
mystery of all,

how were those small
Tyrannosaurs, able to switch

and become these giant,
dominant, super predators?

[narrator]
The keys to unlocking these mysteries, are newly discovered

fossils from around the world.

Researchers have discovered
28 species, related to T-Rex.

[suspenseful music]

Brusatte has conducted detailed analysis of the bones of some

of these specimens.

his goal was to clarify
the process behind

T-Rex's evolution.

The approach he used, is called Phylogenetic analysis.

We have hundreds and hundreds
of those features,

that vary in these dinosaurs.
Some have the bones,

some don't.
Some have small muscle

attachments, some have big ones.

Some have triangle shaped bones, or projections, others have

square shaped ones.
Those kind of features

that are variable.

[narrator]
Brusatte's analysis have
illuminated 366

distinctive characteristics
of Tyrannosaur bones.

And the data he's amassed
form the basis, for mapping

T-Rex's family tree.

The results confirm that
the diminutive Guanlong,

was indeed the most primitive
species of Tyrannosaur.

From the time the first Guanlong emerged, until T-Rex appeared,

took 100 million years.

Over this time, dramatic
evolutionary advances,

created a creature
of unparalleled dominance.

So it is an unusual animal,
a freak of nature,

a feat of evolution.

And I'm fascinated to learn,
to try to understand

how evolution makes an animal,
like T-Rex.

That's the mystery that drives
me, and the research that I do.

[narrator]
160 million years ago, China's
Junggar basin, was home

to the Guanlong.

This species then migrated
to North America.

And about 70 million years ago, T-Rex appeared.

The question is, why T-Rex's
ancestors left

their familiar environment,
and set out,

on their epic journey.

A clue can be found
in the southern reaches,

of the Pacific ocean.

5,000 meters beneath the surface lies an enormous Java Plateau.

Naohiko Ohkouchi, has studied
the formation.

This huge lava mass, was created by a major geological event

120 million years ago.

Deep inside the earth is
a swirling mass of matter,

called the mantle.

Magma suddenly surged up,
erupting through fissures

in the ocean floor.

[explosion]

The Pacific ocean wasn't
the only place this occurred.

All over the world, volcanoes
violently burst to life,

these major eruptions
also occurred

on the Eurasian continent.
Where the primitive

Tyrannosaurs lived.

[fire crackling]

They had no choice but to flee.

[ethereal music]

Leaving familiar territory
behind, they began a journey,

into the unknown.

They headed toward the North,

for a reason.

Climate change, the gases
released by volcanic

eruptions contained large
amounts of carbon dioxide.

This triggered global warming.

As the earth warmed, lush
forests sprouted up

from Siberia, to the Arctic.

Xu Xing believes this greening
of the North, encouraged

the Tyrannosaurs migration.

Triceratops fossils have been
found from Eurasia,

to North America.

And they're often found together with fossils of Tyrannosaurs.

As the forests spread further
North,

the plant eating dinosaurs'
range, expanded.

Scientists believe this is what prompted T-Rex's ancestors

to begin their migration.

Into the unknown, searching
for a new home,

with bountiful game, they start out on their epic journey.

They arrive on the Eastern edge of the Eurasian continent,

in front of them,
is a vast ocean.

And just when it seems
they can't go any further,

something incredible happens.

Tectonic shifts bring
the Eurasian, and American

continents closer together.

Then, a land bridge appears,

closing the gap between them.

A path has opened.

The two siblings make their way toward it, and head

to a new land.

The pair arrives,
in North America.

It's a vast expanse of land,
covered in lush forests.

But, it turns out,

large, meat eating dinosaurs
also live here.

[growls]

Before T-Rex, other carnivorous dinosaurs ruled the Americas.

Scientists have found fossil remains in the deserts of Utah.

Lindsay Zanno is
a Paleontologist who has

explored the area.

She had been excavating
for five years,

then, in 2013, she made
a significant discovery.

And I was coming around
the corner, on a low hill

and spotted some bones sticking
out of the hill,

so I got down and looked
at the bone, and could tell

instantly that it was
a Theropod bone.

A very large Theropod bone
by the looks of it.

And we got very, very excited
right away, that we'd found

a very large species, that had
never been seen before.

[narrator]
Now, the real work began.

Team member, Peter Makovicky
took the fossil to Chicago,

for further study.

His specialty is analyzing
dinosaur bones.

[Peter] The bones we have here,
are parts of the skeleton

of a large carnivorous dinosaur, even though it's big,

and superficially might look
like Tyrannosaurus,

it actually belongs to

a very different lineage

of meat eating dinosaurs.

[narrator] The size of the bones, suggested the dinosaur measured about

11 meters, from head to tail.

It's a relative of Allosaurus,
from the Jurassic era,

and is known as Siats.

Experts believe this dinosaur
had razor sharp claws,

and teeth like knives.

Such features point to
a mega predator.

The name "Siats" actually comes
from the Ute Indian language.

It refers to sort of
a cannibalistic clown monster.

Sort of a dangerous creature,
in their legends.

And it is by far the biggest Theropod, and would likely have

been the top predator
in its ecosystem.

[narrator] Close to the Siats fossil find, Zanno has recently discovered

a relative of Tyrannosaurus.

This is a tooth from one
of the mysterious, small,

Tyrannosaurs we find here,
in these rocks that are about

98 million years old.

We find the tantalizing remains
of tiny little Tyrannosaurs,

about the size maybe,
of a small horse.

[narrator]
A tooth from this dinosaur
is just about 1/10th the size

of that of a T-Rex.

[mysterious music]

So the Tyrannosaurs living here
were quite small,

they were living in the shadow
of dinosaurs like Siats.

[narrator]
The weak, Tyrannosaur siblings
were now living side by side,

with this formidable beast.

[screeching]

[growl]

They were absolutely outrivaled in size, and in power.

Well, I think you know, if...

the small Tyrannosaurs

that were alive at this time,
would have run into Siats,

it would have been sort of like a fox meeting a lion,

or a tiger.

There's no doubt that there's
a very vast difference

in body size, uhm so basically
what we have

is evidence that Tyrannosaurs
were present at the time.

But would have occupied a much
lower tropic level,

among the carnivores,
than Siats.

[soft melodic music]

[narrator] Siats stood atop the ecosystem.

It was a dangerous environment
for the much

weaker Tyrannosaurs.

But somehow, they managed
to survive.

To find out more, Brusatte
has done research all over

the world.

In 2016, he came across
one fossil that provided

some clear answers.

It was found in Uzbekistan,
in central Asia.

An analysis revealed that it was from a new species

of Tyrannosaur.

It's called Timurlengia, and measured three meters long.

At a glance, it doesn't seem
too different from its

its smaller ancestors.

But, internally,
it's dramatically different.

We're able to look
into its brain,

into the ear, using cat scans.

And we can see
it had a big brain,

very intelligent animal.
We can see it had an ear,

that was really sophisticated,
really good at hearing

a wide range of sounds.

[narrator]
Brusatte and his colleagues
took scans of the cranium.

Inside the inner ear,
is the cochlear duct,

which is responsible
for picking up faint sounds.

They found that in Timurlengia, it had significantly evolved.

So what this is telling us,
is that these small Tyrannosaurs

were evolving, bigger brains,
greater intelligence,

better senses; when they were
living, in the shadows.

When they were trying
to survive, in a world dominated

by the Allosaurs, and other
big predators.

[narrator]
Early, small Tyrannosaurs
developed a keen sense

of hearing,

that allowed them to quickly
sense enemies, and escape.

Helping them to survive.

But fleeing wouldn't have been
enough to challenge,

and overtake Siats'
dominant position.

There's more to the mystery
of how descendants of these

diminutive siblings, would have gone on to rule

the dinosaur world.

For many years, the evolutionary path from Guanlong,

to the giant T-Rex, contained
puzzling holes.

So we know a lot about the very
earliest Tyrannosaurs,

now we know they were small,
we know a lot about

the latest Tyrannosaurs, we know they were huge.

But in the middle, there's a gap
in the fossil record,

a dark period of Tyrannosaur
history, where we know nothing.

No fossils.

[narrator]
The Tyrannosaurs 100 million
year evolutionary history,

contains an intriguing hole.

It was during this time,
that the spectacular advances

that led to T-Rex, occurred.

Mark Loewen, has been
researching this mystery.

He's focused in, on an ancient
land mass

on the North American continent, called Laramidia.

The real changing point,
of Tyrannosaur evolution,

was the isolation, and evolution
that happened on Laramidia.

Isolated populations
of dinosaurs,

could evolve in isolation
from other dinosaurs.

[soft mysterious music]

[narrator]
Around 90 million years ago,
global warming,

caused sea levels to rise.

This lead to monumental flooding of the North American continent.

causing it to become divided.

The dinosaurs lived
in the Western part

of the continent.
Much of the land was covered

with steep mountain ranges.

Rising waters drove
the dinosaurs to narrow strips

of level land, where they
became isolated.

In these densely populated
areas, meat eaters would have

a significantly greater chance
of finding prey.

Loewen believes this
is precisely what sped up

the dinosaurs' evolution.

[dinosaur grunting]

This crucible of evolution,
that is Laramidia,

the small populations were able
to undergo dramatic change,

and rapid evolution.

[narrator]
Revolutionary advances
took place in many

different creatures.

Ankylosaurus evolved thick,
bumpy skin,

like protective armor.

Members of the Ornithomimus
family, developed the ability

to run 60 kilometers per hour,
to escape predators.

Similarly pronounced changes
occurred among

the Triceratops' ancestors,
hunted by Tyrannosaurs.

They adapted for survival,
by becoming massively large.

This gave them the power
to repel attacks.

From early ancestors weighing
only 100 kilograms,

They developed into creatures
weighing more than six tons.

But many uncertainties still
remain about

T-Rex's predecessors.

In 2013, Loewen discovered
a fossil, that answered

some questions.

It's from a previously unknown
species of Tyrannosaur,

called Lythronax.

The fossil was buried in soil deposited 80 million years ago.

During the evolutionary
gap period.

The name we chose, Lythronax,
means "gore king",

in ancient Greek.
And, we chose this name because

Lythronax really was, the top
predator in its ecosystem.

[narrator]
The fossil indicates that
Lythronax measured about

eight meters in length.

That represents a remarkable
jump in size, from Guanlong,

its weak ancestor.

This new Tyrannosaur was large
enough to battle

with the massive Triceratops.

Conditions were right
for different species

to influence one
another's evolution.

This phenomenon is known
as coevolution.

[soft ominous music]

[Mark] So Tyrannosaurs were exploiting these prey species,

and also undergoing
rapid evolution themselves.

So it's really an arms race
between the predators,

and the prey species.

And all of these animals

are evolving to have
larger body size.

Both to defend themselves
from predators,

and for the predators to be able to attack the herbivores.

[narrator]
Researchers believe that one
factor supporting

the Tyrannosaurs growth,
was a jump in their

hunting skills.

Their heads, relatively delicate up to then,

widened by about three times.

That made astonishing
improvements in eye

sight possible.

[Mark] One of the things that's unique about Lythronax,

is the fact that it has
forward facing eyes.

Forward facing eyes, occur
in modern animals

that are predators.

And the ability to have
forward facing eyes,

allows you to have overlapping
field of vision,

and perceived depth.

So depth perception, clearly was possible in this dinosaur,

and it's something we associate with hunting.

[narrator]
Depth perception makes it
possible for a hunter,

to accurately grasp,
the distance to its prey.

That would have allowed
Tyrannosaurs to catch prey,

more easily, and turned them
into much more

successful hunters.

[dinosaurs growl]

They would have gotten plenty
of nutrition,

enabling massive growth.

These changes culminated
in the mightiest

dinosaur of all, T-Rex.

[Stephen]
By about 80 million years ago,

a whole new world of dinosaurs
had dawned.

and this was a world that was
dominated by the Tyrannosaurs.

They were the biggest predators,
and they ruled at the top

of the food chain.
And these were the Tyrannosaurs,

that we're all familiar with.

The ones like T-Rex,

the ones that grew so fast,
that they put on five pounds

of weight every day,
during their teenage years.

And they were utterly in control, they were the kings,

of the late Cretaceous.

[narrator] Overwhelming size
wasn't the only result

of the Tyrannosaurs
continuous evolution.

Lawrence Witmer,
is a paleontologist,

who has studied the brains
of T-Rex.

[soft mysterious music]

He's used CT scans of fossils,
to analyze their

brain structure.

The scans point
to new developments

in sensory faculties.

One thing we saw when we started
to reconstruct the brain

of T-Rex, is that the olfactory,
bulbs of the brain,

the part of the brain
that's involved

in processing odors, or smells, were really quite enlarged.

What that told us, is that
the sense of smell, is very

important for T-Rex.

Uhm, it was potentially important for locating its prey.

[narrator] Signals from the sensory organs were sent to, and analyzed

by the Cerebrum.

An index measuring intelligence based on brain to body size,

suggests T-Rex was more advanced relative to other dinosaurs.

[Lawrence] The Cerebrum, which
in mammals like us,

is the seat of intelligence.

and planning,
and problem solving.

Uh, the Cerebrum in Tyrannosaurs
was actually fairly expanded.

We look at their brain
and wonder, whether that

enlarged cerebrum may have
actually had the capacity,

to be involved in, sort of
a coordinated group

hunting effort.

Such that maybe some animals,
would actually drive the prey,

towards other animals,
other Tyrannosaurs, that were

laying in wait.

[suspenseful music]

[narrator]
There he is, T-Rex.

He's not only smarter,

but also has a superior
sense of smell.

Even in the dark of night,
he's able to locate his prey.

[growling]

Aiding his ability to track
game, is his keen eyesight.

The Triceratops tries
desperately to get away,

but there's another T-Rex
waiting in an ambush.

[bones cracking]

Feasting on kills, fuel growth.

The Tyrannosaurs now measured
13 meters.

Their bones grew harder,
and stronger,

and their bodies were covered
in muscles like steel.

Some experts have questioned
whether creatures this big,

had the speed needed
to run down prey?

The conventional belief
was that T-Rex ran

at a speed of 18 kilometers
per hour, that would make

it slower than a human.

Tyrannosaurs were thought
of as slow, and clumsy.

Paleontologist Bill Sellers,
challenged that view.

So it's very hard, when all
you've got is bones,

to try and work at how fast,
an animal would run.

So what we were trying to do,
was come up with evidence

from living animals, that we
could use to work out

how fast fossil animals
would move.

[narrator]
Sellers and his colleagues looked for present day animals,

that would approximate the movements of a Tyrannosaur.

They zeroed in on the ostrich.

[Bill] And these ostriches, are
as close as we can get,

in terms of a modern animal
that's a bit like a T-Rex.

So they've got two legs,
they've got very large bodies,

and they're high speed runners.

A lot of the basic anatomy,
is exactly the same,

so they do make
a very good model.

[melodic music]

[narrator]
Using the ostrich's movement
as a reference, Sellers made

a computer simulation of how
a T-Rex might have run.

The models show which muscles
a T-Rex would have used

when running.

Sellers took particular notice, of the muscles connecting

the thighs, and the tail.

Previously, experts thought
these muscles were merely

for tail movement.

But it became clear, that they
also played a key role

in helping the T-Rex,
to run fast.

[Bill] What it does, is it pulls
the thigh bone backwards.

And so obviously,
this is the main powerhouse.

Even though it's a very
heavy animal, it can obviously

generate the force that it needs
to go at a good speed.

[soft ominous music]

[narrator]
With this model, the average
T-Rex's top speed

increases to 30 kilometers
per hour.

And the strongest could run,
as fast as 50.

The descendants of the primitive Tyrannosaur siblings,

have acquired speed, size,
and intelligence.

But, there's more.

Karl Bates is an expert, on the bite force of dinosaurs.

[unsettling music]

With an enormous bite force,
and enlarged neck muscles,

it probably clamped onto its
prey, and pulled away

at the flesh.

There have been quite a few
fossils found of plant eating

dinosaurs, with T-Rex
bite marks in them.

Where the bite marks go
very deep into the bones.

[loud growl then bones crack]

[narrator] A huge jaw powered
this deadly bite.

Bates has studied the structure of T-Rex's skull.

He recreated the muscles
that connected the upper

and lower jaws.

Then, he used the computer
simulation to quantify

the strength, of its bite.

Bite force, is measured
in newtons.

The lion, known as the king
of the Savannah,

has a bite force
of 4,000 newtons.

The bite force of alligators,
fearsome killers near water,

is around 6,000 newtons.

Compare this to the dinosaurs,
the Allosaurus is considered

to have been the strongest
dinosaur, before T-Rex.

Its bite force, was about
9,000 newtons.

According to Bates, the T-Rex,
had a bite force

of some 60,000 newtons.

That's seven times greater,
than the Allosaurus.

[Karl] 60,000 newtons is a huge
amount of force.

So we're convinced that T-Rex
had a very large bite,

in absolute terms.

And was probably one
of the fiercest biters,

of all time.

[narrator] When a T-Rex bit into its prey, it exerted six tons of force.

That's equivalent to the weight of an African elephant.

[mysterious music]

In theory, such heavy loads
could cause the jawbones

to break.

But something protected
T-Rex from this.

So the skull was very important
for capturing prey,

and consuming prey.

And we were just interested
in how this huge structure,

performed mechanically.

[narrator]
A T-Rex skull is made up of more than 40 different parts.

Here and there are gaps
measuring just

a few millimeters.

These gaps released force
when the T-Rex bit,

and helped to soften the shock.

The T-Rex has this reputation
of being such a deadly,

fearsome creature.

And so we're pretty much
convinced that T-Rex was one

of the most ferocious biters
of all time and worthy

of the title
"King of the dinosaurs".

[narrator]
A creature with both
extraordinary physical

capabilities and,
sophisticated intelligence.

After 100 million years,
the T-Rex had reached

the pinnacle of its evolution.

A pair of T-Rex siblings,

even if they were to meet up
with Siats, former ruler

of the dinosaurs,
they would have no reason

to flee.

[growls]

[growls]

They are no longer the small,
weak, Tyrannosaurs of old.

[both growling loudly]

The siblings set off,
on a new journey.

In search of more prey.

They are heading back
to the Eurasian continent.

Along the way, they pass through areas inhabited

by many relatives
from the Tyrannosaur family.

[ethereal music]

T-Rex was the king of the late
Cretaceous, no doubt about that.

But not all Tyrannosaurs that
lived at that time,

were big, top of the food chain
predators, like T-Rex.

Some of them were actually
quite a bit smaller.

So even when T-Rex was ruling
the world, there were other

close cousins of T-Rex

were doing other things,

filling other roles
in the ecosystem,

and doing a very good job
at it.

[narrator]
In 2014, in Northern Alaska,

researchers found a new species, of Tyrannosaur.

They called it Nanuqsaurus,
after the Inuit word,

for Polar bear.

At six meters, it wasn't even
half the size of T-Rex.

Experts attribute its small size to a lack of game.

The same year,
in Jiangxi Province,

in Southern China, a team dug up an unusual fossil.

The most noticeable feature,
is its long, thin, nose.

It's been nicknamed
Pinocchio Rex, in reference

to the beloved character.

Outwardly, it looks nothing
like T-Rex.

But a bone analysis confirmed it as a new Tyrannosaur species.

Then, in July 2015, scientists
made a discovery in Japan.

Up until then, no one thought
large Tyrannosaurs,

had lived there.

The team found fossils,
of two large teeth.

Each measuring
eight centimeters.

Their size suggests they came from an animal, 10 meters long.

Finds like these, illustrate
the distinctive evolutionary

paths, taken by Tyrannosaurs,
all over the world.

So far, experts have identified 28 individual species.

[unsettling music]

At one point, T-Rex truly
dominated the dinosaur world.

But in the end,
it would meet a cruel fate.

Evidence of this emerged,
in 2015.

Scientists were excavating
in Alberta province,

in Western Canada.

They found this fossil, a cousin of T-Rex,

called Daspletosaurus.

Here and there, researchers
spotted telltale signs

of battle.

A wound deep enough
to pierce the bone.

On the back of the skull,
a part had been bitten off.

Scientists wondered what kind
of creature, could have

inflicted such wounds,
on the mighty Tyrannosaur.

Paleontologist David Hone,
points to an unlikely suspect.

So you immediately have
only one credible candidate,

for these kinds of injuries,
and these kinds of bites,

and that's another
large bodied Tyrannosaur.

[narrator]
Hone says the shape and size
of the bite marks,

indicates a fight between
two members

of the Tyrannosaur family.

They're gonna hunt
at the same time,

or die in the same place,
and have similar territories.

And they're going to come into
these conflicts.

Well I'm sure, every so often there were fights to the death.

And certainly we actually see
evidence of cannibalism

among Tyrannosaurs,
they do kill each other.

[narrator]
In turf battles, even siblings
could become rivals.

And if one refused to back down,

[growling]

[loud growl]

Two frail T-Rex ancestors
set out on a grand journey,

in search of new lands.

On the North American continent, they confronted

countless beasts.

But they managed to thrive.

Their descendants continued
to evolve, eventually becoming

the undisputed rulers,
of the dinosaurs.

But once at the top,
these powerful killers,

turned their awesome power,
on one another.

66 million years ago,
the reign of the dinosaurs,

came to a sudden end.

Experts believe the reason,
was a gigantic asteroid,

that smashed into Earth.

[explosion]

Resulting climate change,
wiped out the dinosaurs.

Including Tyrannosaurus.

[ominous music]

But, was that really the end
of the dinosaurs?

Stephen Brusatte's research,
provides evidence

that it wasn't.

Certain creatures alive today,
are descendants from a branch,

of the Tyrannosaur family.

Birds.

Once the dinosaurs died out,
birds underwent

a spectacular evolution.

New species appeared,
and they became the rulers

of the skies.

They were able to do this,
because of strengths

they inherited from their
Tyrannosaur ancestors.

We always talk about dinosaurs
going extinct

66 million years ago,
when the asteroid hit.

But really not all dinosaurs
went extinct, most of them did,

but one type of dinosaur
survived, and those

are the birds.
So birds evolved from dinosaurs,

and they're actually a type
of dinosaur.

And they live out today,
there's over 10,000 species
of birds.

There's birds flying
around here.

And so these birds

are living dinosaurs

and so birds today,

carry on the genes,
of T-Rex.

[powerful music]

[narrator]
Creatures unlike any
seen before or since.

The free spirit of T-Rex,
lives on.

[music continues]