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00:00Transcription by CastingWords
00:30The environments of the sea and land are so starkly different that a transition from one
00:39to the other seems virtually impossible. Nevertheless, they are the dual stage of a
00:46grand drama which took place over the course of four billion years. Some creatures birthed in
00:53the sea climbed up onto the land while others returned to the oceans from whence they came.
01:04This odyssey from sea to land and then back to the sea is an integral part of the history
01:10of life. It is thanks to the pioneering creatures that first set foot on land that human beings
01:21exist today.
01:44This is a desert located 150 km southwest of Cairo, the capital of Egypt.
01:51It is a vast sea of sand which seems to be utterly bereft of life.
02:05Yet it is this barren land that harbors vestiges of the greatest mystery in the history of life.
02:10To paleontologists who trace the history of life, this is a treasure trove of information. Buried within the hot desert sand are ancient bones. 30 years ago, Philip Gingrich of the University of Michigan made a startling discovery.
02:12here.
02:13Here.
02:14To paleontologists who trace the history of life, this is a treasure trove of information.
02:31Buried within the hot desert sand are ancient bones.
02:36Thirty years ago, Philip Gingrich of the University of Michigan made a startling discovery here.
02:42He discovered the fossil of an ancient whale.
02:47And this means it's an experiment in whale evolution that didn't happen before and was
02:55very successful, but didn't happen after.
03:02You can see it looks like recent bone.
03:04It looks like it died yesterday.
03:07And here it is in the sandstone for 37 million years.
03:14So that's why Wadahitan is important.
03:20He unearthed over a thousand fossils in this place called Wadahitan, or Valley of the Whales.
03:29Thirty-seven million years ago, these parched lands were covered by the Tetes Ocean.
03:42Before Professor Gingrich discovered this fossil, not much was known about the origins of the
03:46modern whale.
03:48Whales are a rare instance where a terrestrial animal returned to the sea.
03:52But until then, the exact reasons for this remained a mystery.
04:01The key to unraveling this mystery is Bacillosaurus, the ancient forerunner of the modern whale.
04:11Thirty-seven million years ago, Bacillosaurus ruled the Tetes Ocean.
04:28It was 16 meters long, with a gaping mouth and serrated teeth.
04:34Unlike most other aquatic creatures, it had a pair of hind legs.
04:57But today, vertebrates dominate the world.
05:00And the hind legs of the Bacillosaurus are a characteristic that is unique to land-dwelling
05:04animals.
05:05Man is one of them.
05:07In order to find the link between Bacillosaurus and land-dwelling animals, we must travel back
05:11eons to the origin of life itself.
05:144.5 billion years ago, Earth in its infancy was an environment hostile to life.
05:36The atmosphere was over 80 degrees Celsius and devoid of any oxygen.
05:46But after millions of years, a miracle occurred.
05:52The first living organisms appeared on the Earth, birthed by the ocean.
05:573.5 billion years ago, the ocean was rich with oxygen, and the horizon glowed with a sapphire
06:11hue of the water.
06:12It was at this time that stromatolite, the first form of life, appeared.
06:32This primitive organism was in fact colonies of blue-green algae, which survived through
06:37photosynthesis and produced abundant amounts of oxygen.
06:45Thanks to this organism, Earth's atmosphere became oxygen-rich, creating an environment
06:50that was conducive to life.
06:55500 million years ago, the seas began to teem with an endless variety of strange-looking
07:06creatures.
07:07They possessed long tentacles and fearsome spines, and were protected by stone-hard armor.
07:14This sudden proliferation of life is called the Cambrian Explosion of Life.
07:19Scientists believe that the ancestors of most of the animals in existence today appeared at
07:23this time.
07:32This creature swimming through the water using its wing-like appendages is Anamalacharis.
07:39Over a meter long, this animal was the largest and most fearsome predator of the Cambrian oceans.
07:44It could pierce through the hard armor of a trilobite with a single bite.
08:03Competition for survival grew fierce, and creatures were forced to modify themselves to survive.
08:09During this time, a transformation occurred altering the course of evolutionary history.
08:14It was the tiny Picaea, a creature no larger than a thumb, which was the constant target
08:19of larger predators.
08:22When we look at Picaea, we are really stepping into the door of vertebrate evolution.
08:29We are there, as we say in English, on the ground floor.
08:33These are the opening moments of this extraordinary story, which is going to take another half
08:38a billion years.
08:42The Picaea developed a stiff rod on its back called a notochord.
08:46It was the precursor of the spine.
08:51But when we look closely, we actually see that there are quite a lot of details.
09:00We can see the front end, and we can see the tail.
09:05And then, most interesting, roughly along here, there is a distinctly different zone.
09:13The notochord proved to be a revolutionary improvement.
09:20The notochord and the V-shaped muscles around it, called mayomeres, worked in concert to
09:24propel this creature forward, giving it unprecedented speed and power.
09:32This is how Picaea probably looked as it swam.
09:38Its propulsion method is similar to that of modern fish.
09:48Despite being an apex predator, animalacara soon became extinct.
09:56But Picaea managed to survive.
09:59While it was armed with neither eyes nor a protective shell, it could elude even the fiercest of predators
10:04using its superior speed.
10:07Picaea's legacy is significant in the history of evolution.
10:10Once you've got a notochord, once you've got the mayomeres, then you're on the way to becoming
10:17a fish.
10:19Once you're on the way to becoming a fish, you're on the way to becoming an invertebrate.
10:23And once you are on the way to becoming a vertebrate, then you're on the way to becoming us.
10:33Had the Picaea become extinct, the history of life on earth would have ended 500 million
10:38years ago in the sea.
10:44Instead, these tiny proto-vertebrates were slowly preparing to become fish.
11:03170 million years ago, the primitive notochords become fully developed vertebral columns.
11:10This is the fossilized ancestor of all vertebrates, including man.
11:16And the black pieces you can see on the surface here are pieces of an arundaspid fish called
11:25saccobambaspis.
11:26Now these are some of the very earliest fishes where the scales and armor was on the surface
11:34of the fishes.
11:37While the fossil is incomplete, it shows the distinct traces of scales, a feature that is
11:42unique to fish.
11:43This is arundaspis, the first fish.
11:56It was covered in scales like the countless fish species that came after it, but because
12:01it did not have fins, it was an awkward and painstakingly slow creature.
12:06Also, it was a jawless fish which sucked water through an opening in its belly and subsisted
12:12on the various microorganisms which it was able to strain.
12:21After another hundred million years, a new fish appeared.
12:35This is a fishing village in Indonesia.
12:37Here, fishermen caught a strange fish which they had never before seen in their lives.
12:43The fish that had become tangled in their nets was none other than a living fossil.
12:47In the gas, it's written inkyo.
12:48Lantas, it was removed from the lava, which brought the будто to the water.
12:52Then, it was thrown out of the water .
12:53It's under the water, then, it wascribable.
12:53It is near the water, under the back window of sea.
12:58It was cutting it, and the fish has cut it down from the water.
12:59It was cut it down to the water, but the people of the sea, it was cut it down here.
13:02But there was an individual, Mr. Darwin, who was seen that in my head,
13:06Mr. Darwin, and did a squrandish fish already seen this fish in the field of training.
13:07Ternyata dia pernah melihat ikan ini di fakultas teknik di Mapala.
13:15Ada posternya besar.
13:19So what does this fish look like?
13:25They open the lid and clear the ice away to reveal the coelacan.
13:31Scientists believe the species had gone extinct during the Cretaceous period
13:35when dinosaurs roam the earth.
13:38It takes the strength of three men to lift the fish onto a table.
13:49These animals can grow up to two meters long and reach 90 kilograms in weight.
13:55Like most other ancient fish species, they are armed with sharp teeth and thick scales.
14:00Also, they carry their eggs with them and give birth to fully developed young.
14:12But the feature that makes this fish truly unique is its fins.
14:16The fish is equipped with large, powerful fins.
14:20This foreshadowed an important new evolutionary development.
14:22This is Miigwasha National Park located in Quebec, Canada.
14:23The sedimentary layers here are up to 380 million years old.
14:25The sedimentary layers here are up to 380 million years old.
14:26The sedimentary layers here are up to 380 million years old.
14:29Hundreds of millions of years ago, this used to be close to the tropical aquarium.
14:32This is Miigwasha National Park located in Quebec, Canada.
14:36The sedimentary layers here are up to 380 million years old.
14:51Hundreds of millions of years ago, this used to be close to the tropical equator.
14:59At the time, a river flowed through this area.
15:01And it was populated by a diverse array of fauna that comprised a complicated food chain.
15:07It is here, in the geological strata of the cliff,
15:10that traces of a significant evolutionary leap can be found.
15:29On exhibit in the museum is a fossil of a fish that is strikingly similar to the coelacanth.
15:35The species first appeared in the Devonian period.
15:38It was a large fish that breathed through its lungs and possessed a set of powerful fins.
15:50Called Eustonopteron, its name literally means powerful fins.
15:59The fins of the fish have a feature that had not been found in previous species.
16:08The fins contain bones.
16:13We have one major element that is articulating with the shoulder girdle.
16:18And this element is the humerus.
16:21Exactly the same element that we are finding in our arm or in the arms of the earliest tetrapods.
16:29The bone fins of Eustonopteron are proof that the limbs of terrestrial animals originated in fish.
16:38But why did this fish develop bones in its fins?
16:44These most likely will be used to move in a very swampy environment.
16:56Just to move among the plants.
16:59So that is giving not just a very thin fin, but that will give a very strong paddle that the animal will be able to push the plants to get into environment to find its food.
17:14Eustonopteron was a skilled swimmer.
17:19It used its powerful fins to propel itself freely through the water.
17:24Also, it was an excellent hunter with well-developed jaws and teeth.
17:53But the Devonian seas were the stage for a fierce battle for survival.
17:58And Dunkleosteus ruled supreme.
18:02At 6 meters in length, Dunkleosteus was a true behemoth.
18:08It was a placoderm which possessed powerful jaws and a thick plate of armor.
18:13Equipped with razor sharp teeth, it often preyed on Eustonopteron.
18:26In order to avoid this vicious predator, Eustonopteron undertook a risky journey.
18:43It left the ocean in search of a new habitat.
18:48It used its powerful fins in order to swim into a river, and then to other bodies of fresh water.
18:58In the water, there are huge fish, some of them about 16 feet long, of all different kinds. Armored fish, all kinds of predatory fish. It was a remarkable period.
19:11During the Devonian period, 370 million years ago, the land was a place full of opportunity.
19:23Trees appeared, foresting the barren terrain, and rivers began to flow.
19:28The fish which populated these rivers heralded a new era in evolutionary history.
19:39Paleontologist Neil Shubin discovered a fossil which would shock the scientific world and be called the missing link.
19:48He discovered this unknown species on Ellesmere Island in northern Canada.
19:52It was named Tiktaalik, or large freshwater fish, in Inuktitut, the language of the local Native American tribe.
20:04Although it had a flat lizard-like head, its scales showed that it was clearly a fish.
20:13And for the first time, we're seeing the kinds of fish that can actually leave the water,
20:17that can make the transition from life in water to life on land.
20:20So all kinds of new things are happening.
20:26Tiktaalik harbors clues to the gradual evolution of land-dwelling animals from the sea.
20:41Unlike most other fish, the Tiktaalik had a flat head with eyes on the top of its skull.
20:46Another distinctive feature is this.
20:53Tiktaalik possessed a neck.
20:56This was a new feature that wasn't present in previous fish.
21:00Tiktaalik uses this neck to rotate its head freely and scour its surroundings.
21:04But the real reason that Tiktaalik is called the missing link is its fins.
21:15Its fins are more powerful and intricately designed than that of Eusternopteron.
21:21Tiktaalik had shoulders, elbows, and even wrists.
21:35Now what's very special about this is not only that these are bones that compare to our own arms,
21:41but if you look at the surfaces of this, there's surfaces for all kinds of muscles.
21:48And not just any kinds of muscles.
21:50Muscles that would have helped the animal do a kind of push-up to support itself against the ground.
21:59Tiktaalik was a revolutionary fish.
22:00It could move its neck freely and scour its surroundings with its eyes located on top of its skull.
22:09Its fins were equipped with elbows and wrists and were strong enough to support its gigantic body.
22:20The appearance of this fish signaled a new movement towards the land.
22:24Thus began the long and arduous process of adjusting to the new terrestrial environment.
22:40So, how did Tiktaalik use its versatile fins?
22:44Mudskippers which live in the tidelands of Korea give us an idea of how Tiktaalik must have moved.
23:01The mudskipper uses its pectoral fins to support itself while crawling around on its belly.
23:06Mudkב
23:18Tiktaalik must have climbed onto the land using its fins in much the same manner.
23:41Water was loaded with competitors, large fish, small fish, everything competing for food.
23:46Some of those fish would eat you.
23:48If you look at land, there are plants there.
23:50There's food there in these early insect-like creatures.
23:54So there are advantages for creatures leaving the water to go to land to remove themselves
23:59from the competition for food resources, but also to escape some of the predation that
24:04was going on in the water as well.
24:14After Tiktaalik, the evolution of the fish became even more accelerated.
24:24Paleontologist Jennifer Klack shows us a sketch of a small lizard-like creature.
24:39This is Acanthostega, a species which marked another turning point in the history of evolution.
24:46Acanthostega is a freshwater fish which lived 360 million years ago during the Devonian period.
25:01It had four almost fully formed legs and breathed air using its lungs.
25:08Also, it had something very unique which Tiktaalik did not have.
25:15One of the first things that we found was that on each limb there were eight fingers or toes, which was a big surprise.
25:32It was the first creature in the history of evolution to have fingers and toes.
25:38Previously, people had thought that the primitive number for fingers and toes was five, because that's what we have.
25:48But it turns out that when tetrapods with limbs first evolved, they had more than five.
25:57Acanthostega has had eight, but we also have other animals from the same time with seven or six.
26:09This is a shallow lake in the late Devonian period.
26:21Acanthostega uses its webbed feet to dart through the water, weaving through various obstacles along the way.
26:33It hides among aquatic plants and snatches a passing fish.
26:40Acanthostega, which possessed both lungs and gills, finally took the first steps onto land.
26:55The adjustment to land did not happen overnight.
27:05The appearance of the first spine, fin equipped with muscle and bone,
27:12and the first legs and toes was the result of billions of years of trial and error.
27:18Millions of years passed by after the appearance of Acanthostega,
27:33and the competition for survival in the water grew increasingly fierce.
27:37But it was a different story altogether on land.
27:40The terrestrial ecology was still full of opportunities.
27:44Then, 280 million years ago, the first complete tetrapod appeared on land.
27:50Descended from Acanthostega, it could only breathe air through its lungs,
27:54and it didn't have to return to the water in order to spawn.
27:59The adaptation to land was complete.
28:03It was a moment of monumental significance on par with man's landing on the moon.
28:09The transition from life in water to life on land is one of the great events in the history of life.
28:20And it's an event that changed the world forever.
28:22For the first time, we have creatures walking on land, feeding on land.
28:26But it's not just an event that's captured in the past.
28:29It's actually an event that's inside our own bodies.
28:32Because many of the features that occurred for the first time in the fish that walk on land are part of us.
28:43The fish that climbed onto land were the weakest members of the food chain.
28:47They left behind the competitive underwater environment in order to survive.
28:51But through change and adaptation, they achieved the Herculean feat of adapting to a completely new and alien environment.
29:06Once tetrapods had reached the land, they began to proliferate quickly.
29:12They diverged into millions of species including amphibians, reptiles, birds and even mammals.
29:25Among their ancestors, mammals reared and breastfed their young and became the masters of the earth.
29:38Once the weakest creatures of the sea, they achieved a brilliant success through their mastery of the land.
29:44But there is a mystery in the history of life that still remains unsolved.
29:48It is the existence of mammals in the ocean.
29:53This is a marine mammal called the dugong.
30:11This is a marine mammal called the dugong.
30:14It uses its fins like arms and feeds on aquatic plants.
30:27It breathes air through its lungs so it must surface regularly.
30:37It also births its young and breastfeeds them.
30:41So why does the dugong possess characteristics that are common to land-dwelling mammals?
30:47The dugong swims away without revealing any of its secrets.
31:02We return to the Egyptian desert in order to unravel this mystery.
31:06Morning Niles Niles Niles Niles Niles Tan
31:13Called Wadahīہ'tan, or Valley of the Waelse, this desert has been designated as a World Heritage by UNESCO.
31:23There is a line of vertebrae in the sand.
31:27Although this fossil was called the Lizard King when it was first discovered,
31:30that was later on proven to be a misnomer.
31:37Bacillosaurus was far from a lizard.
31:41Bacillosaurus represents an early stage of whale evolution.
31:47It's one of the first aquatic whales, fully aquatic whales.
31:52Once the dominant species of the Tetis Ocean,
31:57this primitive whale lived from 42 million to 34 million years ago.
32:05The largest whale at the time, this creature swam by weaving its long body through the water.
32:16It had a pair of underdeveloped hind legs which seemed puny in comparison to its gargantuan size.
32:22This is the clue which will help us unravel this mystery.
32:39This is a Bacillosaurus fossil unearthed in Wadihitan.
32:42This animal was also called the walking whale because of its hind legs.
32:57Although they were small, the legs were fully formed appendages.
33:02They are proof that ancestors of Bacillosaurus once roamed the land.
33:06The general trend, life started in the sea.
33:12And this means that the general trend, from our point of view at least,
33:16is to come out onto the land.
33:18And the whale has gone back.
33:20And so in that sense, it's a reversal.
33:23It's backwards.
33:24There is another mammal that returned to the ocean.
33:32It's Dorodon, a smaller primitive whale that was around 5 meters long.
33:39The raging desert winds revealed whales that had been buried for countless millennia.
33:46Professor Philip Gingrich has recently discovered a new fossil embedded in a cliff in Wadihitan.
33:51It's a fossil of Dorodon.
34:03This is the first time that we know how complete is Dorodon,
34:07how many backbones, how long it is.
34:11It's the first time we know that these whales have legs and feet and toes.
34:16And it's because of the excellent preservation.
34:19This whale with large jaws, serrated teeth, and tiny hind legs is directly linked to land-dwelling mammals.
34:30It was a skilled swimmer that lived in the oceans 37 million years ago.
34:52But its method of swimming was completely unlike that of any fish.
35:00This is another clue which hints at the origins of the whale.
35:04The mechanics of Dorodon are reminiscent of the manner in which land mammals use their spines in order to run.
35:10What is going on 65 million years ago at the end of the Cretaceous period,
35:19a giant asteroid collided with the Earth,
35:24killing off the dinosaurs which had reigned supreme for many eons.
35:28This was the incident which spurred the whale to return to the sea.
35:37After the Cretaceous-Paleogene extinction event and dinosaurs are gone, the marine reptiles are gone,
35:48then there is no top predator in the sea.
35:51And so I see it more as opportunity, not something pushing from behind,
35:57but something pulling from in front.
35:59So which species was it exactly that returned to the sea?
36:04This fossil of Pachycetis is the key to unraveling this mystery.
36:09This creature had four powerful legs and seems to have nothing in common with a whale.
36:15Also, its vertebrae were still attached to each other, making its spine suitable for terrestrial living.
36:25Yet, it had a specialized ear bone inside its skull.
36:33Only whales possess this bone, which is used to detect sounds underwater.
36:39This is a sea near modern-day Pakistan 50 million years ago.
36:49Pachycetis was an amphibious, wolf-like creature.
37:07It took to the seas because they were abundant with food and less populated than land.
37:11It also possessed long, webbed toes, which allowed it to swim freely in the water.
37:25And it possessed a specialized ear bone, which allowed it to hear the sounds of its underwater prey.
37:32The animal used this herring to catch fish with its long snout and razor-sharp teeth.
37:37To hear in water is completely different than to hear in air, and so the hearing apparatus has to be modified.
37:49This ancestor of the whale transformed its body to adapt to its new underwater lifestyle.
37:56Although it could only detect underwater sounds at first,
37:59later developments allowed it to locate the direction from which the sounds came.
38:03This creature changed everything in order to adapt to the water.
38:13Its forelegs became its pectoral fins, and its superfluous hind legs devolved.
38:20Also, its tail became wide and flat in order to propel it through the water.
38:26Lastly, its nostrils moved toward the top of its skull to facilitate underwater breathing.
38:31In this way, the ancestor of the whale adapted completely to the ocean.
38:42Pachocetis, which had maintained an amphibious lifestyle for countless millennia,
38:46finally left the land for good.
38:52It had completed its transformation and become primitive whales such as Dorodon and Basilosaurus.
38:58This return to the ocean is one of the most amazing incidents to occur in the history of life on the Earth.
39:12The fish coming out on land very early in vertebrate history,
39:19and the whale going back to the sea late in vertebrate history,
39:25have this similarity.
39:27I think both are taking advantage of some opportunity.
39:32It's a nice comparison because it shows that evolution is not determined and directional.
39:40Instead, it's opportunistic, and if the opportunity is behind, we will go back.
39:46But this is not the end of the story.
39:53Thirty-four million years ago, around the end of the Eocene epoch,
39:57the Tetis Ocean, which was heavily populated by primitive whales,
40:01began to dry up, and the temperature of the Earth plummeted.
40:05It was at this time that Basilosaurus, the largest whale species of the era,
40:13and its lesser cousin Dorodon, met with different fates.
40:22It was the smaller species, Dorodon, that managed to survive in the frigid waters,
40:26where food had become scarce.
40:28And it became the forefather of the modern whale.
40:41It was the largest whale species, and it was the largest whale species of the earth.
40:51On the other hand, the large and inefficient Basilosaurus could not avoid extinction.
40:57In this way, these rare primitive whales have become buried in the sands of time.
41:13Nevertheless, these prehistoric behemoths leave us with an unmistakable message.
41:24It was the largest whale species of the earth.
41:30Some people are interested in the stars and outer space and how far we can see.
41:36I'm interested in time and how far back we can see.
41:41Because all our understanding and expectation for the future
41:46is conditioned on what we understand about the present and the past.
41:51the study of deep time, the study of life through time,
41:55understanding where we came from, how we are part of the earth,
42:00how we are part of the history of the earth.
42:11To some, fossils are merely the petrified remains of creatures from ages past.
42:17But it is these creatures that risk their lives to forge a pathway into the unknown,
42:21terrestrial environment.
42:23And their legacy has withstood the test of time,
42:26not only surviving in the new environment, but thriving in it.
42:32We are their legacy.
42:51Today's year's day-of-ambiance is withsecurity- circumstances.
42:53So, let's look at how it takes a path to the path of the world.
42:56Let's look at how it is.
42:56This is where the signs of life, the source of life can come from.
42:59However, the central understanding of the earth is in the new environment.
43:01Now, the knowledge of the earth is in the universe.
43:02Then we are in the new environment.
43:04We have the new also at the natalemic ocean.
43:04We have the cost of the earth.
43:05Again, we have the energy that we can be doing.
43:07But it is not only when we are in the new environment.
43:08We have the care that we have to do with the naturalness and that we can be doing.