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of all the animals that live on our planet one extraordinary group dominates
it has produced the largest
the fastest and the most intelligent creatures that have ever lived
they're known as the vertebrates and they all share one vital feature
now I want to travel back in time to explore their ancient origins and
investigate the key advances that led to their amazing success advances that can
also reveal how we came to acquire the characteristic features of our own
vertebrate bodies jaws that bite lungs of breathe ears that can hear because
the story of the rise of animals is also the story of how you and I came to be as
we are
I will find evidence in a series of spectacular fossil discoveries around
the world and within living animals
there with the latest scientific analysis we can bring our ancient
ancestors back to life
and understand how over 500 million years they developed the bodily features
needed to master the scenes
colonize the land and take to the skies
this is the story of the rinds of awareness
the history of life on Earth has been known in outline for many years but
there were a number of tantalizing gaps in it particularly in the history of
animals with backbones when for example did the first signs of a backbone appear
and is it really true that dinosaurs developed feathers and turn into birds
well in recent decades answers have been found to those extraordinary questions
here in China and I'm here to look at them
China is the new frontier for fossil discoveries
excavations here are unearthing links in the story of the vertebrates that has so
far eluded us
I have long wanted to see this sensational evidence of myself I will be
travelling to the frozen north of the country and to the capital Beijing
but to search for the first step in our journey I'm heading south to your nan
province
this is the site of a thrilling discovery that has given us new evidence
for the very first vertebrates
excavators here are exposing a rich seam of rocks known as a trunk yang Fossil
Beds remarkably they contain the remains of creatures that once swam in the
ancient seas 525 million years ago
paleontologist ho Shangguan was the first to discover the unique features of
these beds an astonishing perfection of preservation to find complete bodies
like this is extremely rare when an animal dies in the sea normally bacteria
destroy the soft parts very quickly said all that we can find afterwards are the
hard parts bone or shell why that didn't happen here in this particular part of
this particular sea is something of a mystery it may be something to do with
the lack of oxygen but whatever it was it has given us a privileged view into
one of the most exciting chapters in the whole history of life the beds have so
far yielded over 200 separate species
this was a time period known as the Cambrian the land was still bare and
lifeless but under water it was exploding into a multitude of forms
the major animal groups we know today were appearing on the planet for the
very first time they built their bodies entirely of soft tissue some protected
and supported it with a hard outer casing but none had anything that
resembled a backbone these were the invertebrates
then professor ho and his team found one intriguing exception it's a fossil
called milho kunming yeah but to examine it in detail you've got to look at it
under the microscope
it's features reveal evidence of a new title support not outside the body but
inside this is one of about 30 specimens that have already been found of this
tiny little creature under the microscope
it contains extraordinary amount of detail those marks are marks that have
been made by the excavators needle this is the animal itself this is its head
top of its back and nearly every one of them have these two little black spots
at the front I spots looking farther down the animal there are just some
striations here little bars which are thought to have been the gill bars the
little constructions that carry blood vessels which enabled the animal to
extract oxygen from the water as it flowed over and breathe behind them
farther down the animal there are these bars and of muscle and they were
probably attached to a grizzly rod somewhere in the middle there this is
called the notochord which was the forerunner of the backbone
Millikan mania is the earliest creature we know of that we can truly call a
vertebrate and it seems clear that it used its strong inner rod to move in an
entirely new way as the muscles contract they bend the rod from side to side this
movement pushes against the water and creates forward thrust
here was a revolutionary new way to get around it allowed Millikan Minya to roam
far and wide and escape the dangerous invertebrate predators that were
prowling the seas
the vertebrates will diversify over millions of years to create the
spectacular variety of backbone creatures we see today in every
environment on the planet
fish dominate the seas lakes and rivers the amphibians live in both water and
land the reptiles can survive in the driest places on earth
the birds rule the skies and the mammals have insulated their bodies to adapt to
every climate
we humans have used our greater intelligence to overrun the planet
this astonishing journey was built on a series of key evolutionary steps that
helped our ancient ancestors to exploit their environments and overcome huge
challenges the first of these advances was the development of that inner
support the notochord
back in Europe you can find a creature that represents the next critical step
in our story it lives unobtrusively are often ignored in British rivers and it
sheds light on the challenges those first vertebrates faced
this is a lamprey you might think at first sight that it was a kind of fish
but it's not it's something much much more primitive it has no fins and even
its tail is nothing more than a flattened blade but what is remarkable
about it is that it doesn't really have a true mouth this mouse is just a simple
hole with little bristles about it and it feeds by sucking in water through
that bath and then filtering out little particles of food so this little animal
takes us right back to the time when the first animals with backbones appears on
earth it's a true living fossil
the first vertebrates sink you've had the same kind of mouth and they were
almost certainly limited to the same kind of simple food over time other
forms evolved with different shapes and sizes many of them rather larger than
many Kahn minge but all of them had that very simple mouth than opening at the
front of the body as the lamprey house today if the early vertebrates were
going to really take advantage of the variety of food that was available in
those early seas they were going to have to develop a much more complex and
powerful form of eating machinery
scientists on the east coast of the United States are seeing evidence of
this evolutionary advance not in fossils but in living creatures
Maine New England
marine biologists at the University of New England are studying a group of fish
with a very ancient ancestry they build their skeletons with the same strong
material that formed the grizzly rod of the first vertebrates cartilage they're
the Sharks skates and rays this group appeared among the vertebrates over 420
million years ago and that means we can use them to examine the development
before that split of a remarkable piece of engineering that changed the course
of evolutionary history the jaw
if you look back on the evolutionary tree you'd find that a jaw is a really
important feature to have and it's one of the features that have made skates
and sharks apex predators in the environments in which they live a jaw
hinged to the skull brought the new ability to grab food then rip or grind
it into digestible pieces but where did this amazing piece of equipment come
from scientists have found an answer by studying the way living vertebrates
developed as embryos skates lay their fertilized eggs on the seabed inside
leathery cases called mermaids purses scientists can open
these up and observe them as they develop fed by a generous supply of egg
yolk this skate embryo has a simple structure shared by all embryonic
vertebrates that served as the basis of the first jaw what we see are these
folds and what's really interesting about this is that this skate isn't
about four months of its development and if we take a close look at another
vertebrate we can see it looks very similar here we have the head is gonna
fall down to the body we also see the fault now this is actually a human being
it's thought that the embryos of the earliest vertebrates looked much like
this and that each fold developed into a gill in a skate embryo the folds
furthest from the head keep their original purpose and form the rigid
arches of its gills but the nearest fold has been adapted to form an upper and
lower jaw
in a human embryo the lower folds develop into structures that include the
larynx and the throat but the top fold once again constructs the jaw
the development of the jaw improved the ability to collect food and those that
lacked it with a few exceptions like the lamprey died out but in order to collect
food you have to find it and that led to an improvement in swimming
in the Chinese capital Beijing I've been given special access to a newly
identified missing link this tiny fossil holds clues that are
just fragments and hard to spot but it's the earliest example yet found of a
creature with two pairs of fins
it's called para un Annalee facin it's about 410 million years old
its front part like many other fish at the time was covered by armor plating to
protect it from predators
underneath you can see that it has a mouth and although the lower jaw is
missing you can tell from marks on the upper jaw that it was once there what is
most important about this is its fins just there stumps are visible it had two
fins at the front actual sins
they were shaped rather like the wings of an aeroplane and they have the same
effect creating upwards lift through the water front fins have been found on
older fish but what is interesting is this is the earliest example which has
another pair of fins of the back the pelvic fins this second smaller pair
brought much more stability helping the fish to hold its course through the
water
this system was hugely successful and it made the Sharks the skillful swimmers
that they are today so now the vertebrates had jaws and four fins to
see evidence of the next crucial development I'm heading out onto Lake
Foshan in southern China
these waters are home to living descendants of a group that developed a
new kind of inner support a support that would have huge significance for later
life
here they get a lot of fish like this there's a cop and it's very different
from the Sharks we've been looking at because instead of having cartilage
surgeons carp and others like it have skeletons that are strengthened with
calcium phosphate their bony and most fish today will have very skeletal bone
contains the main material found in cartilage a long stringy protein called
collagen hard crystals of calcium phosphate and strength but the collagen
can still flex slightly and prevent the bones snapping under pressure
these bony fish could subject their skeletons to the far greater forces that
come from increases in speed and agility
they added mobile fan-shaped fins and assumed a multitude of different forms
from their simple origins over 500 million years ago the Sharks and bony
fish diversified to dominate every underwater environment on earth there
are over 35,000 species alive today
the strong inner bony support to the body had evolved in water but it would
prove most spectacularly successful in a completely new environment
for most of the Earth's history until now the land had been empty and barren
but around 450 million years ago first plants than worms and then the ancestors
of insects began to colonize it here were rich pickings for any vertebrate
that could reach them the stage was set for one of the most astonishing leaps in
evolutionary history the vertebrates move on to land but to achieve this
remarkable feat they would need to make a major modification to move around on
land without the support of water these fish needed a way to lift their bodies
up from the surface of the ground they needed limbs scientists have recently
found the earliest evidence for this key moment in Eastern Europe
zal Mia Poland
once a quarry for building stone today this is a hugely significant fossil site
but paleontologists pair albergue and his team aren't looking for bodies
they're looking for the marks the bodies left behind 393 million years ago this
was the soft muddy floor of a tropical Lagoon
you can still see mud cracks here from an episode when the lagoon dried out and
the myrtles flaked up over millions of years the mud solidified into layers of
rock which were then tilted by movements in the Earth's crust by carefully
exposing each layer pair and his team have been able to uncover a series of
intriguing tracks there are three big dimples in the rock there's one here one
here and one down by my feet
these are not emotional hollows is not like Rakesh been scooped away
something's been pressed into the surface of the mud while it was still
soft you can see that from the internal texture here but also from the fact that
you got a slightly erased rim around the edge where the mud has
been displaced so a large heavy animal presumably a vertebrate of some sort
pushed an appendage into the mud here once twice three times in succession the
marks suggest a creature floating and pushing itself around in the shallows
but Peres and his team have found a more detailed set of prints that show an
animal doing something even more radical
this is one of the most important specimens from the entire site and the
reason for that is the pattern for these prints make you can see easily I think
that they make pairs one in front of another in this kind of diagonal
arrangement in order to be able to produce this you need to have limbs that
stick out to the side and which can be swung forwards and backwards rather
freely while you're flexing your body from side to side then you can generate
this kind of pattern a fish crawling trace would not look like this another
extraordinary slab has even preserved the imprint of what pair believes is a
fully formed foot complete with toes so how did the vertebrates make this
astonishing transition from fish swimming to animals with four legs
walking on land in search of clues I'm heading to London and the Natural
History Museum home to the largest collection of plant and animal specimens
in the world I'm here to see the remains of an ancient creature once hailed as a
missing link that would answer such questions
this is a type of bony fish called a sila truth it's fossilized skeletons
have been found in rocks even older than those in Poland its fins have an
intriguing feature not seen in other kinds of fish their base is a rounded
fleshy stump that looks tantalizingly like the beginnings of a lake so
scientists thought that this might well be the ancestor of all land living
vertebrates and then a sensation a living coelacanth was hauled up from the
depths of the Indian Ocean and the museum has acquired several of them here
is the body of a baby coelacanth the coelacanth female retains the egg in
her body until it's fully developed there's its yolk sac and here's its fin
and you can see this fleshy base to it here and there is fin raised question is
was that strong enough to enable a fish like this the hall itself out of the
water and up onto land
now living silicon's have been filmed in the depths of the
sea
it's fresh a muscular fins do certainly help it to maneuver it's 5 foot long
body there is even the hint of a walking pattern but detailed analysis has
revealed that their fins are still a long way from being legs
the ancient coelacanth marked a crucial early stage in that transition but some
characteristics ruled it out as a direct ancestor of the land vertebrates all
land living backboned animals have limbs which have a basic similar bone
structure there is one bone at the top then there are two bones and a group of
bones followed with digits and the coelacanth didn't have that structure
and then recently another fossil discovery was made Ellesmere Island lies
in the icy waters between northern Canada and Greenland
a team of American paleontologists who shot this footage believed that the
rocks here were deposited in the right sort of environment for the vertebrates
moved to land we learned about a sequence of rocks that formed in ancient
stream systems and our hypothesis was that it was in those sorts of
environments where limbs were being favored over fins the arrival of plants
on land had stimulated a surge in life in and around freshwater swamps and this
created new opportunities for the fish that lived here one of the niches that
was being developed at that time was for shallow water predators
you know which fish could find other fish that were living in the shallows
the swamps the the productive ecosystems that were just starting to appear on
earth at that time Ted daeschler and his colleagues believe
that limb like fins could have helped to fish to hunt in this kind of environment
and then on the slopes of a barren valley they made a thrilling discovery
this was the fossil that got us really excited we couldn't have dreamed
actually that we would find something as well-preserved as this one it's about
the front two-thirds or half of the body as you can see a very complete skull and
a large piece of the body including parts of the fin the team found features
that match the profile of a shallow water predator eyes placed on the top of
a flattened head and ranks of sharp teeth they gave it a local Inuit named
Tiktaalik
we can now work out from its bones how Tiktaalik moved around in those swamps
and shadows
in deep water it must have swam like any other fish
but further examination of its bones showed that it could also move its body
in a far more radical way one of the really amazing aspects of Tiktaalik that
we've noticed is this evolution of the neck there was not a rigid connection
between the skull and the rest of the body
Tiktaalik is the first vertebrate we see that has freed up the neck and when you
think about it all limbed animals including ourselves
would not be able to move our head independently of our shoulders if it
were not for these innovations that were occurring in form like Tiktaalik a
flexible neck allowed two tonic to point its jaws at its prey when space was too
cramped to maneuver its whole body but it was the Finns that provided the
team with the most exciting evidence
behind the spiny rays there were lobe like stumps like those of the coelacanth
but tectonics bones revealed a pattern that was much closer to the basic
structure of limbs we learned a lot about the fin of Tiktaalik from this
specimen now this is a cast of all the different bones that we found in
association including the shoulder girdle here but that is the complete fin
skeleton from the front fin so I'm a lobe finned fish here is my front fin
call it a limb now but here is Tiktaalik s' front fin we've got a shoulder joint
and it's very important that there's a shoulder joint which is oriented a
little bit laterally a little bit down in Tiktaalik very different from an
animal that's just swimming with its fin and paddling along this fin seem to be
oriented beneath the body so this is the humerus we all have a humerus that's the
first bone in the front appendage we have a ulna and a radius so you and I
all limbed animals have an ulnar and radius we have some wrist bones and we
actually then have something which like a wrist could bend together and allow
this fin to sit down and to contact a surface with a surface area and so when
we see all of these features we see a structure which is very much like our
limbs so here is a fish using its fin in a very limb like way
Tiktaalik heavy-duty fin still helped it to swim but if he hit the shallows the
bones and joints would help to push itself up and punt around
but this new limb didn't just help mobility in the water
it became the driving force behind one of the most spectacular events in
evolutionary history
the arrival of the first vertebrate animals on land
over time creatures evolved that spent most of their time out of water they
formed a new group recall amphibians and to survive on land they had to solve a
new challenge they had to be able to extract oxygen not from water like their
fish ancestors but from the air fish use gills to absorb oxygen into the body in
air gills quickly try out and stop working China is the home of a rare and
fascinating creature that can show us how the ancient amphibians overcame this
problem today the biggest amphibian alive is this creature
the Chinese giant salamander it breeds parthy through its skin which has these
long saps on it and that absorbs oxygen from the water but it also breathes
it's gonna come up and as it does it snatches a gulp of air blows a few
bubbles and sinks down again
it's jaw acts as a pump forcing air down into the body here oxygen is absorbed
into the bloodstream from two inflatable sacks with permeable walls lungs because
they're enclosed inside the body they don't dry out the lungs it uses are just
simple pouches coming from the back of the throat but nonetheless they were the
first kind of lungs that animals had the forerunners of the air breathing organs
that all of us land living vertebrates now
from their origins around 365 million years ago the amphibians took on many
different forms
over 7,000 species now live in a variety of habitats on land and in water
they include salamanders frogs
a newts but two things tide amphibians to water first their skins are moist and
if they dry out they die and secondly their eggs like this frogs form are
covered in nothing more than jelly and they have to be laid in water or very
least in moist conditions and until the vertebrates can solve those two problems
they would not be able to colonize the dry parts of the land
then a group of pioneers appeared with an amazing new feature to their bodies
we can find the evidence of this next step by looking at animals that can
survive far from water today this little creature is a lizard they call it in
these parts a tree dragon and its body is very much the same shape as a
mountain long body with the backbone and two pairs of limbs but there's one
crucial difference between an animal like this an amphibian its skin is not
moist it's dry we can see what has changed by putting the two types of skin
under the microscope the skin of an amphibian is smooth with living cells
visible on the surface a lizard skin is much rougher because it contains large
amounts of keratin a protein similar to that from which our own fingernails are
formed
keratin filled cells dry out and layer up to form scales this creates a barrier
sealing water inside the body we humans have inherited this keratin barrier in
our skin allowing us to maintain up to 70% of our bodies as water animals with
this body plan became a huge success they evolved into a great number of
species big and small we call them reptiles but the reptiles
still had to overcome a second challenge how to lay their eggs out of water
I have come to roofing in southern China to see evidence gathered by local
scientists of the ingenious solution thank you very much these eggs were laid
by a reptile and as you might imagine a pretty big one at that
the first reptilian eggs almost certainly had a leathery covering rather
like those a turtle lays today but the eggs are different they have a hard
covering a shell and you can see where the weight of the salmon that eventually
covered them and fossilized them bore down upon them they crushed that shell
but the pieces are still in place from examining modern reptile eggs we know
that this shell must have been made of hard calcium carbonate and it must have
supported an inner fibrous membrane together they made the egg watertight
and mat meant that the animals that laid them no longer had to go back to the
water today their eggs as all amphibians had to do instead they could go to the
driest part of the land and breed a nest and lay their eggs so all the dry land
was open to them
the amphibians had spearheaded the move tool and now their descendants reptiles
were able to establish themselves in its dry spots over nine and a half thousand
species now inhabit our planet
but the limbs that help the vertebrates emerge from the water began to present
problems when it came to walking efficiently on dry land because they
projected sideways it took a lot of effort to hold their bodies off the
ground then around 230 million years ago one set of reptiles developed an amazing
solution these eggs were laid by an animal belonging to the most successful
of all reptile groups a group that dominated the world for 100 million
years the dinosaurs
more than 150 different species of dinosaur have been found in the rocks of
China alone and over a thousand worldwide
and they too depended on a crucial advance a radical modification of the
bone that connects the leg to the body the hip
this is Lou from the Souris a plant-eater the early reptiles had legs
which sprayed out from either side of the body and left the body very close to
the ground but a change in the shape of the hips of the dinosaurs enabled them
to bring their hind legs underneath the body and so lift it up and give them
greater freedom of movement and some of them including Lou fungus horas were
able to support the entire weight of the body on the hind legs this new hip
along with sturdier leg joints allowed the dinosaurs to take longer strides
and support heavier bodies they became the largest animals that have ever lived
on that but this new way of walking was also the
first step on the road to an even more radical evolutionary advance it was from
this group of two-legged dinosaurs that they came a truly astonishing
development that we are only just willing to understand and that was to
lift the vertebrates to a completely new level the backbone animals had colonized
the Seas and invaded the land but there was one final habitat to explore the
skies
another extraordinary Chinese fossil bed is providing the missing evidence for
one of the great mysteries in evolutionary science the intriguing link
between dinosaurs and birds
I'm heading for Lyon in Provence to fulfill a long-held dream and see the
site of these discoveries for myself
these rocks are about 125 million years old at that time this part of China was
topical and the land was covered with a lot of freshwater lakes and in those
Lakes was washed sediment which formed these bands here but every now and again
the sediment changes color and that is ash that was spewed out from a nearby
volcano so that about that level there there were a lot of skeletons awaiting
the rediscovered and when they were discovered they revealed some
sensational facts about dinosaurs the most sensational for a very long time
this fossil was one of the most remarkable to emerge a two-legged
dinosaur about the size of a cat it's been named Sinosauropteryx its discovery
revealed an intriguing feature never seen before on a dinosaur up its tail
and down its back a covering of what looks like fur
fresh finds have revealed that a wide range of two-legged dinosaurs had skin
covered by very similar hair like filaments but what were they for in
Beijing there are the crucial specimens that answered those questions this is
one of the world's leading institutions in the study of dinosaur evolution
professor Shushan and his colleagues have been analyzing another larger
specimen of Sinosauropteryx it too retains traces just fragments of the
mysterious filaments if you look at near the tail the dark scenes there near the
tail there are single filaments just like our hair sure are simple shushing
has been puzzling over their function together these filaments create a
covering like fur so the most likely answer is that they serve to keep these
dinosaurs warm but detailed examination has suggested an additional and very
different function experts at the Institute have taken minut samples and
examined them under powerful magnification they contain intriguing
structures some are lozenge-shaped some spherical
investigators identified them as mallanna somes microscopic capsules that
contain pigment they would have given the filaments on sonĂs or opera's tail
color based on our analysis you see stripes when the one button would like a
wet bran wet brand really yes definitely is a beautiful pattern of course you can
see oh that's maybe for display or communication or do we know how it held
don't tell us that have not I can move in different two actions and in most
cases our guess is is our poor horses so it's like you ring-tailed lemur waving
its tail around is a display dinosaurs may have used these colored furry bands
to signal to other members of the species or to act as camouflage but then
came a discovery that suggested another far more significant function
I have been granted privileged access to the underground vaults of the Beijing
Museum of Natural History to look at one of the most important creatures yet to
be found in the fossil beds of Loughnane
this is anchiornis a creature that's clearly a dinosaur
it's got powerful legs here ending with toes with sharp claws on them and its
head which has been detached lies here upside down but you can see the jaw
which has teeth in them but what is spectacular about this particular
specimen is the perfection of the preservation of these structures they
show that the simple filaments have developed into something far more
complex the central stalk has tiny strands branching out on either side the
filaments have become feathers analysis of them has shown that the crest here on
the head was a Rufus red color and the body feathers were stripes black and
white
their feathers all down the legs and looking at the density of them on the
forearms here it does look very like a wing so the question is could this
animal fly could this be the moment when a dinosaur became a bird
a clue to the answer could come from the environment in which it lived at this
time this area of northern China was covered in lush forests animals that
could climb trees would be able to collect food that was not available on
the ground they could also find safety from ground living predators shushing
and his colleagues see evidence that anchiornis adapted to a tree living way
of life by putting its feathers to a new use anchiornis has some features that
suggest him trail eating lifestyle for example you look at that there Anke on
his toe they have very curved claws and also
they have a big feathers attached to their feet if an keone is really an
animal then you have a good reason to believe that a flight start from TRADOC
which means the brezza ancestor can take advantage of gravity
and under start their journey to the sky
because and hyuna's lived high up it could use its feathers to glide
it must have needed all the feathers growing along its front limbs hide limbs
and tail to create a large enough surface to catch the air and slow its
descent
it wasn't capable of flapping flight but at a hundred and sixty million years old
it's now the earliest creature we know to have use feathers to fly
the guiding dinosaurs would eventually give rise to a whole new group of
vertebrates the birds
over 9,000 species crowd our skies today
an astonishing evolutionary journey had enabled the vertebrates to dominate
every corner of the planet
it was a journey that began in the cambrian seas over 500 million years ago
and that led to the development of a set of body parts that we ourselves would
ultimately inherit jaws and the bony skeleton from the early fish
limbs and lungs from the amphibian
water tight skin from the reptiles
by the time the birds appeared on the planet the early pioneers of another
major vertebrate group had also evolved at first they were tiny but they were
destined eventually to dominate the earth they were the mammals most I
daresay were little better than the snack food the dinosaurs but all that
was about to change a devastating meteor strike that many believed triggered a
mass extinction we don't know exactly what happened but certainly 65 million
years ago all the dinosaurs disappeared but some of the birds and mammals
survived and with the bigger dinosaurs gone the world was up for grabs
next time I'll be investigating the extraordinary rise of the mammals to
discover how they developed a remarkable set of new bodily features to become the
most complex and successful vertebrates yet powerful senses a radical new way of
producing their young and monstrous bodies we will also see how we humans
finally arrived on the tree of life with hugely advanced brains that would allow
us to out-compete all other species on the planet
how did the mayor can't cross the road Stephen fryer pops the question to
Catherine Ryan Josh Widdecombe and Phill Jupitus next on BBC two in Qi