Original subtitles

(mysterious music)

(dramatic music)

(roaring)

- [Narrator] Where do birds come from

and who were their ancestors?

For a long time, these questions have remained unanswered.

Their family trees stopped abruptly at the oldest

known species, a fossil found in 19th century Germany.

Archaeopteryx whose name comes from the Greek

for ancient wing.

But since 1996, thousands of animals unearthed in China

have shed new light on the origin of birds.

(screeching)

(intense music)

This abundance of discoveries proves that most dinosaurs

were not covered in scales but clad in feathers.

Some of these feathered dragons could even fly.

The extent of the Asian jigsaw puzzle is so vast

that it ties modern day birds to remarkable distant

cousins and suggests a multitude of relatives.

(snarling)

During the Jurassic Period,

between 200 and 145 million years ago,

the supercontinent Pangaea opened up

creating separate land masses.

At the edges of this world, China and Siberia formed

a huge peninsula with a temperate climate

similar to that of modern Europe.

(mysterious music)

The break up of the continents was accompanied

by volcanic eruptions, particularly in China.

A paradise in waiting, inhabited by strange creatures

like Anchiornis.

(chirping)

Meaning near bird, this little dinosaur

is completely covered in feathers.

The size of a modern day pigeon, Anchiornis

is a long lost relation.

The descendants of this light weight dinosaur

survived better than other large Theropods

The group that includes all carnivorous dinosaurs.

(snarling)

Including Guanlongs.

They are efficient hunters, three meters long

and weighing 50 kilograms.

(snarling)

To escape, Anchiornis was capable

of short gliding flights while its pursuer

was firmly stuck on the ground.

(intense music)

(snarling)

And yet, Guanlong also had feathers.

What were they used for?

(dramatic music)

(roaring)

Erupting volcanoes spewing fine ash

and noxious gases froze a moment of Jurassic life

for eternity, helping us answer some of these questions.

This dinosaur paradise has become

the feathered dinosaur's Pompeii.

A huge range of new species has recently

been discovered in one of China's many construction sites.

Over the last two decades,

in the Liaoning region, paleontologists have collected

thousands of specimens hidden for millions of years.

These magnificent fossils are in a state

of almost perfect preservation.

Thanks to the mixture of extremely fine clay

and volcanic ash sediment.

- Those volcanic eruptions (mumbles)

and bury their bodies so that's why we have

such beautiful skeleton and I include soft tissue

preserved, so that's why we come here.

- [Narrator] Paleontologist Xu Xing and his colleagues

from around the world can trace the chaotic history

of flight and feathers in these rocks.

- The feather preservation is really amazing.

- [Narrator] Like detectives, they examine the clues

to understand what feathers were used for.

And discover how some dinosaurs from the Theropods family

turned over the course of millions of years into birds.

The first piece of evidence in their inquiry

was discovered at the end of the 19th century in Germany.

Towards the end of the Jurassic Period,

Europe was partly submerged under a shallow body of water

called The Tethys Sea.

About 150 million years ago,

Germany was dotted with tropical islands.

(ominous music)

Pterosaurs the first flying vertebrates

have dominated the skies for 80 million years.

This is Germanodactylus one of 150 species

of Pterosaurs discovered.

These flying reptiles are not dinosaurs.

Their fine skin stretches over their elongated fingers

to create leathery wings.

This membrane along with powerful muscles

and hollow bones makes them masters of the skies.

(tense music)

But the Pterosaur's aerial supremacy is about

to be challenged by the very first birds.

Such as Archaeopteryx.

A primitive bird whose claws at the ends of its wings

raise suspicions amongst 19th century paleontologists.

Its fossils were found around the modern

German town of Sondershausen.

A tropical acapellago during the late Jurassic Period.

Some islands harbored salted lagoons

where dying animals avoided scavengers.

And were buried by soft mud that preserved them

in minute detail.

(soft piano music)

Eberhard Frey commonly known as Dino Frey

is the resident expert.

- This is the famous Sondershausen laminated limestone

and you can actually see the sediments stapled

up like the leaves of a book.

Inside the leaves of this rocky book,

this is where Archaeopteryx was found together

with many other fossils and it's the specialty

of this rock that it is very, very, very fine grained

and inside this mud, fossils are preserved

like in a tin and this is why this entire area

is so valuable as a window in Jurassic times.

- [Narrator] The locals use these stones

to tile their houses.

In the process, uncovering highly prized treasures

in the history of paleontology.

(mysterious music)

In 1868, faced with the Archaeopteryx,

British biologist Thomas Henry Huxley asserted

that this was a transitional fossil

between reptiles and birds.

(dramatic music)

A friend of Darwin and an ardent defender

of the Theory of Evolution, Huxley was an expert anatomist

capable of skilled fossil analysis.

- Until the year 1861,

before Archaeopteryx first discovered,

the only creatures that were known to have feathers

were the birds.

It was apparent that this is a fossil bird.

Thomas Huxley looked at it very closely

and he discovered signs that this bird

could also be a dinosaur actually, a carnivorous dinosaur,

actually shares characters of the two

making it the mixing link between dinosaurs and birds.

That was a sensation at the time.

(bouncy music)

- [Narrator] The Darwinian idea of natural selection

is therefore very recent.

Huxley had the insight to see that Archaeopteryx's teeth,

clawed wings and bony tail meant that it had similarities

with kon-sog-ni-sus dinosaurs.

Predatory relations with the Velociraptors.

(snarling)

Archaeopteryx was certainly no acrobat but it had feathers

and it could fly.

Its collar bones had already fused together.

A vital step enabling the wings to flap efficiently

and gain altitude, allowing it to hunt and nest in trees.

(gentle music)

Throughout the 20th and 21st centuries,

more Archaeopteryx fossils were unearthed in Germany.

(mysterious music)

- This is specimen number 11.

It's the latest specimen and it came to light

in the year 2011.

Despite its fragmentary, it's not completely preserved

because its skull is missing.

It still shows us some features which are previously

unknown, one of them is that the tail end

shows a V shaped feather configuration

and the second is that you can see in this specimen

the extent of the feather travels along the legs.

- [Narrator] The feathers on its feet are intriguing

since modern birds no longer show this characteristic.

Is this an exception?

What is sure is that this feature

has not been selected by evolution.

Just like this giant marine reptile.

A Liopleurodon.

(insects buzzing)

Washed up on the shores of the lagoon,

it is a godsend for Archaeopteryx.

The flies attracted by the carcass provide a hearty meal

for this insect eater.

But being out in the open is dangerous for Archaeopteryx.

An opportunistic Germanodactylus sees the prospect

of a protein rich meal.

(tense music)

And doesn't appreciate the competition.

(dramatic music)

Once the mightiest creatures in the skies,

Pterosaurs became extinct by the end

of the Cretaceous Period 65 million years ago.

While Archaeopteryx descendants grew in number.

Bogged down at the bottom of the song-hil-fan lagoon,

this remarkable fossil launched the debate

on the relationship between birds and dinosaurs.

But with insufficient proof, this theory was shelled

for more than 100 years.

Until new evidence came to light,

at the end of the 20th century in China.

In 1993, in Liaoning,

a huge fossil deposit was found dating

from the Cretaceous Period, 125 million years ago.

This region formerly known as Manchuria

comprises fertile farm land with fields of corn and pasture.

Farmers were the first one to uncover fossils inadvertently.

You can see her tomb at a foot of a cliff fashioned

by volcanic eruptions.

Layers of gray mud alternate with red ash.

Transported to Beijing, these fossils allow 21st century

researchers new insights into the feathered dragons.

Like Sinocalliopteryx, the first discovered in 1996.

This specimen remains a source of fascination

for one of China's most famous paleontologists, Xu Xing.

- I remember clearly at that time when this discover

was announced, everyone got so excited.

We are kind of shocked by the beauty of the fossil.

If you look at this specimen closely you see the feathers

cover the whole body.

Over the hair, over the back, cover all the tail.

A little bit here also I mean lame.

Basically feathers are quite simple.

They are more like your hair.

Before this discovery, some paleontologists believe

some bird like that should have feathers

but no, we have real evidence so that's totally different.

- [Narrator] The discovery of this feathered covered

fossil was astounding.

For the first time, they had found a dinosaur

with avian characteristics.

Proof that they were part of the same lineage.

In conifer forests, growing in the shadow

of volcanoes, lived Sinocalliopteryx.

It belonged to a group

of carnivorous dinosaurs called Theropods

These predators use sight and smell to hunt.

(ominous music)

One of his favorite victims is zang-e-o-tier-ium.

One of the first mammals.

Sinocalliopteryx's feathers looked like the down

covering modern day chicks.

They are so different from bird feathers

that for a long time, skeptics dismissed them

as mere hairs.

(screeching)

(screeching)

In 2010, Xu Xing focused

on Sinocalliopteryx's strange feathers

which looked like the down covering modern day chicks.

He began with careful observation of these feathers.

By taking a sample and putting it under the microscope,

scientists discovered fossilized pigments.

These are melanosomes, cells that give feathers their color.

Xu Xing discovered circular shapes

that produce a brown pigment and stick like shapes

that create a gray color.

He deduced the Sinocalliopteryx was the color

of a squirrel with lighter stripes on its tail

but that's not all.

- We can use melanosomes to infer the color,

but more importantly for us,

we wanted to use that information to support

the hypothesis that those dark impression

in this particle specimen are part of feathers,

not something else because if melanosomes are present

we can say quite confidently those are primitive feathers.

- [Narrator] Sinocalliopteryx was undoubtedly

covered in feathers but this land animal

was incapable of flight.

So what use was this dino fuzz?

Did it protect this warm blooded animal from the cold?

Possibly, but this theory is not easy to prove.

To learn more about the climate in Liaoning

during this period, Xu Xing teamed up

with the laboratory in France.

This Theropod tooth bought back from China

by geologist Romain Amiot holds the key

to this meteorological mystery.

- [Translator] A lot of researchers thought that fossils

from that time couldn't preserve the weather conditions

recorded during the animal's lifetime.

It was a big challenge.

We were going to test something unknown.

Could we find out climate information or not?

- [Narrator] In a sense, we can test the water

the dinosaurs drank.

A chemical reaction with the oxygen preserved

in tooth enamel reveals the temperature

of the atmosphere 120 million years ago.

Romain made a major discovery that radically

altered our preconceptions.

- [Translator] At the time, there was a global climate

that was similar or a little colder

than current temperatures which is very different

from what we thought about the period of the dinosaurs

that we had imagined as hot, tropical

and the same throughout the world.

Where Liaoning is, the climate was similar

to what we have in the north of France

with very harsh winters.

So dinosaurs would have seen snow in winter.

So feathers were an insulating material.

It meant they could keep warm and keep active

throughout the year like any other warm blooded animal.

- [Narrator] Coincidentally just as Romain published

his research, the discovery of large sized dinosaurs

confirmed his work.

Yutyrannus, the aptly named feathered tyrants,

were the super predators of the time.

Due to their large size, the remains of T-Rex's cousins

are kept in a warehouse in a suburb of Beijing.

(mysterious music)

- Yutyrannus is really an amazing animal.

It's a really big animal, about one half tons

in body mass.

Its body covered by feathers, really long feathers,

so this is unexpected.

Traditionally we thought,

when an animal get bigger it's mostly the same.

The loss feathers, reduce feathers,

at least feathers are kind of sparse,

but here we have a large body that dinosaur

with dense, and long feathers.

So this is bizarre.

- [Narrator] The fact that such a large warm blooded

animal was covered in feathers suggests

that its body size was not sufficient

to regulate its temperature.

So the climate must have been very cold.

The discovery of the largest feathered animal ever found

confirms the hypotheses of a temperate climate

with harsh winters.

(solemn music)

It proves that the Theropod dinosaur of Liaoning

wandered into the winter snow 125 million years ago.

And that the feathers of the little Sinocalliopteryx,

the huge Yutyrannus, protected them from cold temperatures

in this region of the northern hemisphere.

(tense music)

(roaring)

(roaring)

The insulating property of feathers remains

a feature in modern birds.

But it is not sufficient to explain how surface

dwelling dinosaurs evolved over millions of years

to become birds.

Among the Theropods living in Liaoning,

was there only one type of feather?

And at what state did dinosaurs begin to fly?

Over time, Chinese paleontologists have unearthed

many feathered creatures.

On some fossils, like the Caudipteryx,

discovered in 1998, Xu Xing found feathers

that were not just simple filaments.

With its large feet, it looks much like an ostrich.

- In this fossil, there's some really

beautiful feather impression.

Here you see two hands of this animal

and here is a middle finger.

You see feathers attached to the finger, this surface.

They go this way so quite a big feathers.

(soft music)

- [Narrator] Caudipteryx literally meaning tail feather

comes from the same Chinese site

as Sinocalliopteryx, in the same period,

125 million years ago.

(screeching)

(gentle music)

Scientists imagine that these chicks were imprinted

on their mothers just like modern birds

and followed them everywhere more or less.

(squeaking)

Weighing almost 20 kilograms,

the female Caudipteryx can't fly,

neither can her youngsters.

So why do these animals have long feathers?

Could they serve a purpose other than warmth?

Feathers begin as a simple filament.

Which divides to form a pom pom before barbs

appear around the hollow shaft.

But at this stage in their development,

feathers are symmetrical and air passes through them.

- So it is not fly animals, it's fast running animal

living on the ground, so what's the function?

Apparently those feathers are not used for flight.

That was a possibility most people believe

is a display.

- [Narrator] Just like many birds,

the males and females were physically very different.

Paleontologists believe that the male Caudipteryx

displayed his shimmering feathers in order

to attract females.

(screeching)

These cultured rituals along with natural selection

stimulated an anatomical transformation.

Caudipteryx were among the first Theropods

to possess a shorter tail that supported their display furs.

(screeching)

In order to fly, they were still missing

a fundamental element, flight feathers.

(tense music)

Seen under a microscope, this feather comes

from another dinosaur discovered in 2000

by Xu Xing himself.

It is a vital clue to solving the mystery

of the origin of flight.

- Here the feathers are highly asymmetrical.

Asymmetrical feathers are normally considered

to be associated with flight capability.

- [Narrator] These feathers are identical to those

of modern birds.

It may be proof that some dinosaurs could fly.

- Microraptor is definitely the most amazing species

that discovered so far.

It is dinosaur but you see it has asymmetric flat feathers.

Not only are the feathers on the arms,

but also on the feet.

We call the (mumbles) condition.

This is really, really bizarre.

I don't know, we have quite good evidence

suggesting this foreign condition is related

to the origin of flight.

- [Narrator] For a long time, paleontologists

believed that two legged dinosaurs run along the ground

in order to take off,

but Microraptor's climbing claws opened

up a new possibility.

125 million years ago in the part of China

that Microraptor called home,

the ground was fertilized by volcanic ash

that encouraged the growth of lush vegetation.

Tall trees add a vertical dimension to the landscape

and the Microraptor, meaning small thief,

takes advantage of them.

(chirping)

Microraptors sported feathers on its arms and legs.

With its full wings, it was probably the world's

first base jumper.

(chirping)

Full wings offer an advantage for gliding,

but not for walking.

A Microraptor on the ground, is a Microraptor in danger.

(tense music)

(screeching)

According to Xu Xing, tree dwelling feathered dinosaurs

like these would evolve to become birds.

To better understand this transition,

paleontologists teamed up

with an ornithologist Zhongue Zhou.

In front of him is an incredible collection

of primitive birds found at sia-tomb.

Like the feathered dinosaurs from the same site,

they all date from the Cretaceous period

125 million years ago.

- I think there are over 500s of specimens

of Confuciusornis collected in this museum alone.

I think this is the largest collection

Confuciusornis in the whole world.

This bird, like Confuciusornis, they're only later

than the earliest bird Archaeopteryx

and they are transitionally many flight-er apparatus,

many features.

- [Narrator] Despite the claws on their wings,

they are very similar to modern birds.

They no longer have teeth or a long bony tail.

They also have a focular, the famous chicken wishbone

for attaching muscles to wings and the males

have two ceremonial ribbons ornamenting their behinds.

(solemn music)

This sexual variation is similar to that

of the feather dinosaur called Dipteryx.

Like him, the male has long feathers that he uses

to lure the ladies.

(screeching)

Competition is tough and courting displays

are often interrupted.

(volcano rumbling)

- Also you can see the bird start climbing the trunk

with very big claws in the wing.

Now you see the bird can perch on the branches

of the trees because the hallux of the foot

is already reversed, much like a modern bird.

(screeching)

- [Narrator] Confuciusornis' narrow feathers were not well

adapted to gliding, but would've allowed it to fly

by flapping its wings, albeit clumsily.

But natural selection is at work,

retaining only the most adapt genes.

Yet the presence of many birds found

at the same location as feathered dinosaurs

does not necessarily prove that they were related.

If birds had already diversified 125 million years ago,

Yutyrannus and other Theropods may have been merely

an evolutionary dead end.

So when did the first birds appear?

Did they share a common ancestor with feathered dinosaurs?

And how did their ancestors begin flying?

To answer these questions, Chinese paleontologists

have one last card up their sleeves.

West of Liaoning, a new fossil bed was revealed

during the construction of a motorway.

In 2009, a finely preserved Anchiornis dating

from the Jurassic Period was found near here.

It's become a crucial piece in Xu Xing's puzzle.

- This site is very important for at least one reason.

We know that Archaeopteryx, the earliest known bird

is from about 145 million years but most other feathered

dinosaurs are from early Cretaceous or even later.

So this dinosaur was living in 160 million years ago.

Earlier than Archaeopteryx so that means there are some

feathered dinosaurs predates Archaeopteryx,

the earliest bird.

That's cracked the time sequence.

- [Narrator] This new fossil puts an end to the debate.

Feathered dinosaurs are undoubtedly older

than the first birds.

Today, Xu Xing discovers a fish.

Confirmation that Anchiornis lived in a rich ecosystem.

This little four winged Theropod must've been

a victim to giant predators.

(screeching)

In the Jurassic Period, Pterosaurs like these Darwinopterus

ruled the skies.

With talon like claws and a wing span of over a meter wide,

they were the equivalent of modern day birds of prey.

Their ability to fly and perform aerial acrobatics

was beyond that of the feathered dinosaurs.

Faced with this constant danger,

Anchiornis sought shelter in the forest.

But this little dinosaur was also threatened

from the ground.

Its only shelter lies in the restricted area

between the ground and the sky, the trees.

It glides down to feed in the under growth.

Its surface area is smaller than Microraptor

so it falls more quickly.

With its long back legs, Anchiornis is built

like a sprinter, but its lengthy feathers are a hindrance

on the ground.

Its long legs are an advantage for foraging

or rushing to the nearest shelter.

If such a thing exists.

(tense music)

(screeching)

Though clumsy, Anchiornis showed the dinosaurs

attempted to fly from trees using four wings.

On this rare fossil, the rear leg feathers are visible

to the naked eye.

To refine his theory, Xu Xing continues his research

using a medical scanner.

X-rays of Anchiornis' skeleton will be digitized in 3D

in order to study its biomechanics.

- But honestly there are some debates

how exactly the animals use their leg wings.

Some people believe the leg wings are not really

related to flight, maybe it's a display structure.

If you look at other dinosaurs, their leg normally

is underneath the body.

(mumbles)

One possibility may be Anchiornis can project

its leg slightly laterally.

- [Narrator] To compensate for the lack of a wishbone,

Anchiornis used its rear leg feathers to improve

its gliding ability.

The discovery of Anchiornis proves that dinosaur flight

was a result of trial and error in the evolution

of anatomy and feathers.

Surprisingly, new information about the origin

of feathers was soon to appear from over the border.

In Siberia, in the summer of 2013,

the first Russian feathered fossils made their appearance.

1,500 kilometers north of Beijing,

in the Transbaikal Step, a team of Russians and Belgians

worked together at the excavation site.

When local geologists found the first bones,

they invited paleontologist Pascal Godefroit

from the Royal Institute of Belgium

to take part in this revolutionary discovery.

- [Translator] We're at the Kulinda deposit

in southeast Siberia.

The hills you can see behind me, date from the Jurassic

Period between 145 and 160 million years ago

and Russian geologists who were prospecting in the area

in 2010 found the first dinosaur bones

which have been extremely important for reconstructing

the evolution of plumage and feathers in dinosaurs.

- [Narrator] As curiosity aroused,

Pascal assembled a team to search the site for themselves.

It's a lengthy process, requiring a deep layer

of soil to be removed to get to the fossils.

But after several days, the teams work starts

to show results.

- [Translator] Look at that.

That's quite a big deal.

Just there at the edge.

Oh wow, that's one.

(speaks foreign language)

So here at the edge of the plate,

you can see very fine little filaments

and these are feathers, dinosaur feathers.

You can see that the filaments converge towards the base

so these are composite feathers.

It's a primitive kind of down that we find

on some primitive dinosaurs.

- [Narrator] Compared to the impressive Chinese discoveries

these fossils may seem a little underwhelming

but the paleontologists are thrilled to discover

a completely new animal species.

During the Jurassic Period, the Chinese peninsula

was covered in a vast forest of conifers.

While Siberia was much more hostile.

The arid climate had a huge seasonal

variations in temperature and intense volcanic activity.

One of the keys to conserving precious fossils.

Only fragments of skeletons are found at Kulinda.

To begin with, the Russians thought that the feathers

came from fossilized birds.

The scales from crocodiles.

And the bones from a small predatory dinosaur.

But Pascal was not convinced by this hypothesis.

In 2014, he reanalyzed all the fossils

and suggested an entirely different explanation.

- [Translator] It's a bit like going into a cemetery

and gathering up loose bones.

You have small tibias, large tibias,

little femurs and big femurs but they all have

the same ornithology so we can tell they all come

from the same type of dinosaur

that we called Kulindadromeus.

Because of the large number of disconnected bones

that we found at Kulinda,

we now know that Kulindadromeus was a small

herbivore dinosaur that was fast, slender and agile.

- [Narrator] This is the first ever feathered herbivore

dinosaur to be discovered.

A separate branch of the dinosaur family tree

from the carnivorous Theropods.

Kulindadromeus lived in herds.

Just like wildebeest migrations in Africa,

large predators such as Sinraptor must've closely

followed the movements of these dinosaurs.

(roaring)

- [Translator] This is a real revolution.

What it means is that all dinosaurs who potentially

have had feathers.

- [Narrator] Feathers would have appeared

on an ancestor that was common to both groups.

It could be as old as dinosaurs themselves.

First seen in the Triassic Period 220 million years ago.

(ominous music)

The misfortunes of this group of herbivores

have led paleontologists to the origins of feathers.

(roaring)

Thanks to Kulindadromeus, we now know that the first

feathered dinosaur, the common ancestor

of the carnivores and the herbivores

remains to be found in fossil beds going back

to before the Jurassic Period.

(roaring)

But who knows what other secrets could be found in Siberia?

And what clues could be hidden in other parts of the world

to document the early history of the bird dynasty?

(whimpering)

(solemn music)

(volcano rumbling)

(dramatic music)