Original subtitles

*

*

This is the upper region of the Amazon River.

A descendant of dinosaurs inhabits this dense jungle.

It is a bird called the Hoatzin and has deep maroon eyes.

Living in swamp areas, the Hoatzin only

eats leaves and fruits.

It has a few peculiar characteristics.

The reason why Hoatzin is called a descendant of

dinosaurs is because juvenile Hoatzins have

two claws on each wing.

These claws will disappear once they become adults.

So no claws can be seen on these adult Hoatzins.

But the bird has inherited something more

marvelous from dinosaurs.

Feathers.

A marvelous invention of nature.

*

*

This exhibit at the Natural History Museum in Berlin,

Germany, shows beautiful bird feathers.

There is one eye-catching display of a

feather imprinted on stone.

It is a delicate imprint that perhaps,

a master painter could have drawn.

But in reality, it is a 150-million-year-old fossil.

And the feather is from Archaeopteryx,

the oldest known bird.

Yet, Archaeopteryx is more like a dinosaur

than a bird in some ways.

It has a bony tail like a dinosaur and

sharp claws on its wings.

It also has teeth.

However, its feathers are unmistakably bird feathers.

Is Archaeopteryx the earliest ancestor of modern

birds or is it a dinosaur?

*

*

150 million years ago, a single feather from an

Archaeopteryx fell and became fossilized, holding

the key to the the evolution of birds and dinosaurs.

Some facts in history are sometimes

upended by new discoveries.

In 1996, a Chinese farmer in a small village in Liaoning

discovered a rock that challenged the existing body

of knowledge on dinosaurs.

The rock contained a fossil of a creature

that looked like a lizard.

But what made this find astonishing was that

it had primitive feathers.

The fossil was that of a carnivorous dinosaur.

*

*

Sinosauropteryx means "Chinese reptilian wing" and several

other fossils of this dinosaur have been found,

ranging in different sizes.

It was an important discovery because it showed a

dinosaur with a furry coat.

Fossils are not just ancient rocks.

They can reveal secrets from the past.

Xu Xing, a famed paleontologist identified

feathers on a 120-million-year-old fossil.

The dinosaur was covered with feathers.

Unlike existing bird feathers, these

were thick, proto-feathers.

This dinosaur was Beipiaosaurus, a carnivore.

*

*

More fossils of feathered dinosaurs were unearthed.

China became the focus of interests among

paleontologists from around the world when the first

feathered dinosaur was found in the country.

Long ago in prehistoric times, feathered dinosaurs might have

been the dominant species on the Asian continent.

The Linheraptor lived in a region that

is now Inner Mongolia.

As an agile predator, it could quickly chase prey and

pounce on it using its claws.

It was a bird-like dinosaur that had proto-feathers.

The velociraptor was portrayed inaccurately in a movie,

where it was shown without feathers and

larger than its actual size.

The feather-covered velociraptor looks quite

different from typical illustrations of dinosaurs.

There is a mystery as to why carnivorous

dinosaurs needed feathers.

Let us take a look at another feathered dinosaur.

*

*

Despite being small in size, Dilong is a member of

Tyrannosauroidea of which the Tyrannosaurus rex belongs to.

However, Dilong's proto-feathers had different characteristics.

Dr. Xu Xing thought dinosaur feathers were

used as thermal insulation.

A fossil discovered in 2004 supported his hypothesis.

Meilong means sleeping dragon in Chinese.

*

*

Standing erect, it reveals its small body.

*

Meilong was a small carnivorous dinosaur and

probably took naps after chasing small prey all day.

But it moved like a bird.

Meanwhile, Professor Richard Prum of Yale University found

that dinosaur's proto-feathers were similar to that of

the earliest bird feathers.

This is a simple hollow tube.

This is the kind of feather that's very like the

hypothesized structure of the very earliest feather.

A simple tube.

The black tube that Professor Prum showed us is from the

feather of cassowary, a bird that inhabits tropical forests

in Australia and New Guinea.

The Cassowary is a flightless bird that uses

its feathers to stay warm.

Likewise, primitive feathers probably kept dinosaurs warm.

*

The first feather was probably hollow like a cassowary's

feather and began as a strand of fiber.

This simple tube-shaped fiber evolved into a complex

structure with interlocking barbules.

A vaned feather has branches, which are called barbs.

Barbs, in turn, have smaller branches called barbules

that have minute hooks.

The hooks interlock to The evolution of feathers began

from such a simple structure.

And over millions of years, it evolved and diversified into

various colors and sizes.

Magnificent feathers cannot be replicated by man.

Other mysteries about feathers can be unlocked

through scientific analysis.

Prof. Prum has studied many different kind of birds

and found evidence that dinosaur feathers had other

uses than thermal insulation.

One of the more exciting discoveries that have recently

been made about fossil feathers have been the discovery that

one of the most abundant or common pigments of feathers

actually fossilized very well under good conditions.

This fossil is dated 160 million years and has

well-preserved pigments.

It is the fossil of Anchiornis, a feathered dinosaur.

This bird feather is magnified under an electron microscope.

The tiny flecks are melanosomes which contain

melanin, a common natural pigment in nature.

It determines the color of the feathers.

Professor Prum and a team of researchers discovered melanin

pigments in an Anchiornis fossil as well.

Melanin pigments that make the black,

brown and deep reddish colors of hair or feather are

packaged into tiny organelles that look like grains of rice.

The pattern of melanin pigments found in the

Anchiornis fossil is similar to that of Hamburg chickens.

Anchiornis probably sported colors similar to

modern chickens 160 million years ago.

Featuring a red comb, the Anchiornis had white and

black-striped wings which it likely showed off to rivals.

Modern birds like Hoatzin use its feathers

for extravagant display.

The male's beautiful plumage helps it court females.

Not only does the Hoatzin ward off competitors with its

plumage but it also uses it to court the female.

Meanwhile, Dr. Xu Xing learned that Anchiornis also

used its plumage for courtship.

Long feathers grew on Anchiornis' hind legs.

And they served a special purpose.

The feathers allowed Anchiornis to

glide like a flying squirrel.

Australia boasts unique animal life that is not found

elsewhere on the planet.

The ostrich-like emu grows as tall as 2 meters,

making it the world's second largest bird.

But it is flightless.

The reason why emus cannot fly is because of their feathers.

It's impossible to fly with such easily bendable wings.

What does a feather of a flying bird look like?

The rachis or shaft is not placed in

the middle of the feather.

In this vaned feather, you can see that rachis is closer to

one side, demonstrating its asymmetrical design.

Flightless birds like an ostrich have feathers where

its shaft is placed in the middle,

giving it a symmetrical design.

A bird with such feathers cannot fly.

Only birds that have asymmetrical feathers can fly.

In order to create the physical forces that are

required for bird flight, the feathers on the bird

have to be asymmetrical.

A flying robot was tested at KAIST to see how asymmetrical

and symmetrical feathers affect flight.

A basic model of symmetrical feathers found in flightless

birds was tested in a wind tunnel.

The "feathers" in the model could not withstand the

crosswinds and began shaking vigorously.

Under stronger winds, the "feathers" were blown away.

This feather model would never make flight possible.

Now the asymmetrical feather model was tested

under the same conditions.

The model stayed stable under the crosswinds.

And maintained its balance under stronger winds.

People cannot tell if a bird has asymmetrical feathers on sight.

But all birds of flight have these feathers.

Even this 150-million-year-old feather of Anchaeopteryx

has an asymmetrical design.

This means that Anchaeopteryx was probably able to fly.

Paleontologists who studied feathered dinosaurs realized

this as an important discovery.

The theory that Anchaeopteryx could fly despite

its dinosaur-like body...

They needed to focus on feathered dinosaurs that had

asymmetrical feathers like the Anchaeopteryx.

Dr. Xu Xing and his team of researchers found a dinosaur

that had asymmetrical feathers.

The feathered dinosaur, Microraptor lived

120 million years ago.

The curved feet in this microraptor fossil is an

indication that it dwelled in trees like the anchaeopteryx.

Its body was also covered with feathers.

Peculiarly, it also had long feathers on its hind legs.

Faint patterns showed it had feathered tail too.

Possessing feathers designed for flight,

the microraptor's legs also had long feathers.

Paleontologists from around the world were drawn

to this four-winged dinosaur.

Among them was Professor Larry Martin of

the University of Kansas.

Microraptor is the animal that turned the corner on the

theories about the origin of flight.

Microraptor had a tail that was several

times the length of its body.

From studying its bone structure,

paleontologist can tell how it flew in the air,

its habitat and if it was a meat-eating carnivore.

We were able to see that the bones would articulate in such

a way that it could for instance,

climb a tree very easily.

But it could also take the arms and spread them out to

form a wing and to take the legs and spread

them out to form a wing too.

This is a model of a Microraptor with its muscle

structure and feathers recreated.

With its wings spread, it looks like a bird.

The long feathers on it legs prove that Microraptor

inhabited trees like modern birds.

It means that it couldn't walk comfortably on the ground,

let alone run.

And that means that this was an animal that probably

lived entirely in the trees.

And was using these wings to glide from tree to tree.

120 million years ago in a prehistoric forest...

This four-winged microraptor climbs a tree using its claws.

Like a modern bird, the microraptor

was at home in trees.

was at home in trees.

When it moved to another tree, it spread all

four of its wings to glide.

This is probably how the earliest flight in the

animal kingdom occurred.

The discovery of the microraptor and four wings

and recently anchiornis, which also has four wings,

in fact, is older than Archaeopteryx, indicates very

strongly that the proto-bird was an arboreal quadrupedal.

Like the microraptor, which lived 120 million years ago,

the hoatzin dwells in trees.

But it has far superior flying capabilities

compared to the microraptor.

The secret to how feathers and flight evolved is revealed

by studying Hoatzin feathers.

Using a microscope to magnify the feather,

you can see small barbs with hooked barbules

interlocking with each other.

This is a characteristic of feathers from birds of flight.

After the evolution of a coherent vane or a tight vane

with hooked barbules that create a surface,

it was only then we could have the evolution of feathers

that were useful in flight.

As feathers evolved into more complex structures,

they improved the flying capabilities of birds.

This proves that feathered dinosaurs that mastered flight

were actually a new evolution in dinosaurs.

The theory that feathered dinosaurs could fly have

altered our knowledge of dinosaurs.

Like the velociraptor, there were other dinosaurs on

land that had primitive feathers instead

of scaly lizard-like skin.

The mounting evidence of feathered dinosaurs has also

affected studies linking birds to dinosaurs.

We conceptualized dinosaurs as being big,

sluggish lizards with their tails dragging on the ground.

They're actually very active animals like birds.

And then when we found the feather impressions on that

that only cemented the argument.

Dr. Luis Chiappe of the Natural History Museum of Los

Angeles County proposes a theory that velociraptors

might have been the ancestors of birds.

As evidence, he points to their bone structure.

This is the wishbone of the velociraptor.

There's a bone here in the wrists that allowed the wrist

to fold and essentially to swivel just the same way that

it swivels in modern birds.

Here's a reconstruction of archaeopteryx.

You can see again the wishbone.

You can see the details in the wrist that are very similar to

those of the velociraptor.

The feathered dinosaur velociraptor lived 80

million years ago and might have been evolving

into a bird at the time.

On its chest, it had a V-shaped bone.

And its wrist could swivel side to side.

The direction of its hip bone was facing forward.

This bone structure is similar to an owl's bones.

A V-shaped chest bone is a pronounced

trait among flying birds.

Dr. Chiappe posits that the bone structure of dinosaurs

give away telling signs of how they evolved.

This is the University of Montana Flight Laboratory.

Professor Ken Dial uses a different approach

from paleontologists and ornithologists

to study bird flight.

He unlocked the secrets to flight by studying how chicks

flap their wings to climb.

A one-day hatchling cannot fly at all.

But it uses its wings to prevent itself from slipping

as it climbs a ramp.

Birds use their wings to move aerodynamically

through the air.

To help their feet when they're going up an incline or

they use their wings when they're coming to descend down.

Over time as the young bird's wings become more developed,

its ability to fly also improves.

An adult bird with fully-grown wings can easily climb a

ramp at a 90-degree angle.

Every day if you watch baby birds develop,

they're teaching you how a partial wing,

how a half a wing, how a three-quarters shaped

wing can be functional.

Every day they grow up.

The way young birds learn how to use their wings step by

step could have been similar to the evolutionary

stages of feathered dinosaurs.

During the period when feathered dinosaurs began to

fly, there was also a flying reptile species.

This is the fossilized footprint of a Pterosaur which

was called the ruler of the skies.

Some pterosaur specimens were rather small while others

became the largest flying animals of all time with

wingspans exceeding 10 meters.

The size of this pterosaur can be deduced by

the size of its footprint.

Pterosaur first appeared 250 million years ago, which is

much earlier than the evolution of feathered dinosaurs.

These reptiles ruled the skies unchallenged

for 200 million years.

But the wings of a pterosaur were different from that of

feathered dinosaurs or modern birds.

Professor David Martill of the University of Portsmouth is

knowledgeable about pterosaurs and explains the

structure of its unique wings.

This is the palm of the hand.

Whereas our palm of the hand is very, very short.

In pterodactyls, it's very, very long.

And then most pterodactyls have three very,

very short fingers just here.

They seem to have lost the thumb.

But they have one very, very long finger,

which is equivalent to our number four finger and this

finger extends all the way along here.

So this is an enormous finger.

One of the longest fingers you'll find

in the animal kingdom.

And all of this makes the spar of the wing.

This is the support of the wing

How did the pterosaur fly with such long wings?

First, it had to crouch into a launching posture,

after which it would have lifted its rear legs and

then lean on its forelimbs.

It could flap its wing at this point to fly.

With its membrane covered wing,

the pterosaur flew gracefully in the air.

It had the ability to cover hundreds of kilometers in a

single flight And experts considered the pterosaur to be

a very well-adapted animal as it survived for 200 million years.

Its bone structure gave it an advantage.

Pterosaur had hollow bones that were

less than a millimeter thick.

These hollow bones are even lighter than bird bones.

Air occupied the inside of the bones to assist flight.

But the thin membrane on its wings was

fragile and easily infected.

If a pterosaur had an injured wing,

it could not fly until it healed.

Thus, these fragile wings, which were susceptible to

the environment, put the pterosaur at a

great disadvantage later on.

65 million years ago, practically all life on earth

was wiped out by a cataclysmic event.

Pterosaur and all dinosaur species became extinct.

If there was a period of even just perhaps,

six months where they were unable to fly because of high

winds and other aspects of the climate that made it

problematic for them to feed, it would be very,

very easy to wipe out the last few pterodactyl species.

Yet, how did birds survive this unfortunate event which

exterminated pterosaurs?

The answer is found in prehistoric birds.

The prehistoric bird Confuciusornis existed

125 million years ago.

Upon inspecting the bone structure of Confuciusornis,

signs of the evolution of bird flight are revealed.

Its tail bone was short and stunted and it had a toothless

beak like a modern bird.

Based on these characteristics,

Confuciusornis look similar to birds of today.

*

Prehistoric birds were able to avoid extinction because their

bone structure allowed them to fly under any conditions.

Not only did they have feathers but they also had a

body structure that was highly adaptable.

Yanornis lived in the same period as Confuciusornis

and is even more similar to modern birds

than its prehistoric relative.

Small feathers were discovered on its wings.

And its shoulder blades were well developed,

allowing it to flap its wings vigorously.

Yanornis lived near the coast where food was plentiful.

It flew freely in the skies 125 million years ago.

It was able to adapt to a variety of environments,

allowing the species to flourish for millions of years.

Yanornis is an ancestor to modern birds.

Birds that descended from prehistoric birds continued

to hone their flying ability.

The condor that inhabits the Andean mountains can fly 6000

meters above sea level easily.

Inhabiting the coastal regions of the Atlantic Ocean and

Pacific Ocean, frigatebirds can reach a maximum speed

of 400 kilometers per hour.

Hummingbirds, which are the world's smallest birds,

can beat their wings 80 times per second.

They can also hover mid-air and fly backwards.

They can also hover mid-air and fly backwards.

One flock of snipes migrated from Australia to Siberia,

flying nonstop for five days and covering an

astonishing 10,000 kilometers.

When a bird can fly for five days nonstop using a million

wing strokes and not develop lactic acid buildup - and

therefore, just fall out of the sky - you come to learn

that there's something about the physiology of birds that

have become very specialized in certain groups

for long distance movement.

Birds have populated diverse habitats through their amazing

feats of flight that defy human comprehension.

Every October, Baikal teal arrive in South Korea and then

fly a thousand kilometers to their nesting grounds in

Siberia when spring comes.

Birds were able to survive and prosper on earth because they

possessed the ability to fly.

Dinosaurs that once ruled the planet developed feathers.

These feathers gave dinosaurs the ability to take flight and

opened up new, unlimited possibilities.

Flight feathers are one of the most interesting and important

innovations in the history of vertebrate life.

We have witnessed this marvelous innovation around us.

So dinosaurs still rule.

We call this the age of mammals because we write the textbook.

But if you're just counting number of species,

the dinosaurs have been running the show for 240 million years.

A single feather dated 150 million years

contained many secrets.

Archaeopteryx is believed to be the ancestor of birds.

But perhaps, the feather of Archaeopteryx

is a dinosaur feather.