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00:00530 million years ago, long before the age of dinosaurs,
00:13no living creature, not even a blade of grass, existed on land.
00:19Earth was desolate and barren, littered with rock and sand.
00:30But deep in a world below the sea,
00:35a host of curious creatures flourished in a habitat rich with life.
00:43The common ancestors of man and all other vertebrates appeared around this time.
00:49So did other mysterious and bizarre life forms that have since vanished from the planet.
01:19.
01:22.
01:24.
01:26.
01:29ORCHESTRA PLAYS
01:59ORCHESTRA PLAYS
02:29ORCHESTRA PLAYS
02:31The Rocky Mountains stand majestically over western Canada.
02:49500 million years ago,
02:52this entire mountain range was at the bottom of the sea.
02:55Hidden inside these craggy peaks is a geological treasure trove of perfectly preserved Cambrian
03:04fossils.
03:09Discovered in 1909, this remote part of British Columbia is known as the Burgess Shale.
03:22During the brief summer, a group of scientists led by paleontologist Dr. Desmond Collins from
03:28Canada's Royal Ontario Museum arrives at the site.
03:39The mountain camp will be their home for the next several weeks as the team prepares to
03:44search for clues to our past.
03:49Buried in the layers of this sedimented rock are the fossilized remains of ancient animals.
03:58Well, the Burgess Shale is, I think, is no doubt the most important fossil locality in the world
04:04because it shows more of the possibilities of life which were actually developed on Earth.
04:11Most fossils are the remains of skeletons or shells of animals, the hard parts which have
04:15been mineralized.
04:16In the Burgess Shale you get those fossils but you also get the soft tissues along with
04:22the hard parts and also the remains of animals which have no hard parts at all like worms and
04:27jellyfishes.
04:31The more we dig, the more we find and the more we find, the more we realize we don't know.
04:36It's sort of a cumulative thing.
04:42It's an exciting place to be because the next rock might expose an entirely new form of life
04:47no one has ever seen before.
04:48More than a hundred specimens from the Cambrian period have been collected here.
05:06The finely layered rock peels away like leaves from an ancient book.
05:14Animals emerge one after another, almost leaping off the pages.
05:26Many of these animals are extraordinarily complex.
05:38Some even look like creatures out of science fiction.
05:45The sheer volume of animal life preserved in the Burgess Shale makes it one of the world's
06:01most enticing spots for fossil hunters.
06:04Only a small section has been excavated to date.
06:11At one time, these rugged, mile-high peaks lay deep below the sea.
06:22Half a billion years ago, towering cliffs harboring a city of ancient life rose from the sea floor.
06:33Then, one day, a powerful landslide.
06:40In an instant, cliff dwellings turned to rubble.
06:50Buried under tons of muddy debris, every living creature would perish.
06:56But in this airless tomb, the remains would lie in pristine condition, untouched by scavengers or decay.
07:13Repeated landslides deposited sediment, eventually forming what is now known as the Burgess Shale.
07:19Paleontologists from across the globe visit this site, hoping they will be the next to tap into its rich cache of Cambrian history.
07:34An air of anticipation hovers over the mountainside where Dr. Collins and his team explore.
07:41Where's Matt?
07:43Matt!
07:44Come here for a second.
07:46Another chapter of our ancient past comes to life.
07:57Wow.
07:58Wow.
07:59Doctor, what is it?
08:01I don't know.
08:03That's completely new.
08:10That's completely new.
08:15So what are you going to call it?
08:16What's the name for it?
08:18I guess this is a, you found it, didn't you?
08:20I guess that's an Andrewsaurus.
08:22Solving the mysteries of the Cambrian age has challenged researchers here at Cambridge University.
08:43One look at the pristine Burgess Shale fossils in the early 1970s piqued the imagination of Dr. Harry Whittington.
08:51He decided to launch a full-scale study of the enigmatic Cambrian creatures.
09:04This was one of the fossils that fascinated him.
09:09An animal with a long nozzle protruding from the head.
09:14At first, it looked like an extension of the mouth.
09:18But closer inspection placed the mouth at the tip of the U-shaped digestive tract, way below the head.
09:28If the mouth and nozzle weren't even connected, Whittington wondered, what purpose could the nozzle serve?
09:35To find out, Whittington re-examined fossils from his own collection, along with recently excavated Burgess Shale finds.
09:48To his delight, he discovered a new specimen of this strange creature.
09:52With a small drill, he slowly chipped away the rock layer covering the fossil.
10:05Split in two like a pair of scissors, the tip of the nozzle soon emerged.
10:11The nozzle, it seems, was used like an elephant's trunk to grasp food and carry it to the mouth.
10:24Dr. Whittington noticed another peculiarity.
10:29The white spots on the head were thought to be the eyes.
10:34But there were more than two.
10:37This creature had five eyes.
10:47The animal Dr. Whittington reconstructed based on fossil analysis amused the scientific community with its cartoon-like features.
10:56I drew a reconstruction of it, and I showed it at a meeting of paleontologists, and they all shouted with laughter,
11:15because it was such an impossible looking animal, with no legs to walk on, must have swum by flapping these flaps.
11:28And it had this great process in front of it, and these eyes sticking up on the head.
11:34But I think that's, well, the most careful investigation I can make suggested that that's what it was really like.
11:46That's what I was interested in.
11:48Resurrected after more than half a billion years of extinction, this offbeat organism was named Opabinia.
12:09One by one, other ancient life forms discovered at the Burgess Shale were reconstructed by Dr. Whittington and his research team.
12:30The work could be tedious.
12:32At times, it took over three years to reassemble just one fossil.
12:36But gradually, the story of Cambrian life was unfolding.
12:48Because of its bizarre appearance, this creature was named Hallucigenia.
12:57With spikes protruding from its narrow body, it's hard to tell which end is up.
13:02Nectocharis looks as if it were fused from two different animals.
13:09It has a head like a shrimp and body like a fish.
13:12Dynomyscus resembles a flower, but it's really an animal, not a plant.
13:23On the inside of the petal-like parts, the mouth and anus lie side by side.
13:28Odonto Griffiths has small tooth-like protrusions around its mouth.
13:38Its name literally means, mystery with teeth.
13:41At one time, Cambrian fauna were thought to be simple creatures with little diversity.
13:52But Dr. Whittington and his team proved otherwise.
13:54These life forms already exhibited complex structure and a rich variety of shapes and design.
14:05Among them were creatures so unique that at first they defied any biological classification.
14:1110,000 new species developed during this era.
14:24The Cambrian seas were exploding with life.
14:28But why this evolutionary burst occurred is still unclear.
14:31Over the past century, scientists have been stumped by one particular Cambrian mystery.
14:48The appearance of a predator that terrorized the ancient seas.
14:52Even hard-shelled trilobites like this one were not immune from attack.
15:07The W-shaped scar was no doubt the mark of a large animal with extremely sharp teeth.
15:14But no fossils of such a monster had been recorded.
15:18There were many pieces to the puzzle.
15:24A fossil first identified as an ancient jellyfish.
15:32Dr. Simon Conway Morris was one of the Cambridge researchers who made the connection.
15:38But it's a very peculiar sort of jellyfish because it looks more like a pineapple ring
15:43in as much as there is a hole right the way through the center of the specimen.
15:48And there's no jellyfish looking like that today.
15:50And we imagined, or at least I did,
15:52that somehow the jellyfish was able to place itself over the prey
15:56and then the prongs in the middle would squeeze together.
16:00Around the same time, another colleague, Dr. Derek Briggs of the University of Bristol,
16:05was studying some peculiar shrimp-like fossils.
16:12Named Anamalocaris, or odd shrimp, the fossils were classified as the tail of a shrimp-like creature.
16:20Curiously, close to a hundred of these fossils had been found,
16:31but not one with its head intact.
16:33Dr. Briggs began to suspect there was something wrong with the shrimp tail theory.
16:52If it were in fact a tail, why were there no traces of a digestive tract?
16:57Perhaps, he speculated, these were legs of some other animal.
17:10A giant, centipede-like creature might have been able to attack a 6 to 12-inch trilobite.
17:16But aside from these legs,
17:19no fossil revealing the body or mouth of such an animal could be reconstructed.
17:23Dr. Briggs' research came to a standstill.
17:38That is, until 1982,
17:41when Dr. Whittington happened upon something interesting
17:44while rummaging through his fossil collection.
17:45The imprint on this fossil looked like the body of some animal.
17:56Just what kind of animal was harder to tell.
17:59Curiously mounting,
18:12Whittington carefully chipped away at the surface
18:15and was stunned by what emerged.
18:20The fossil now revealed a shrimp-like tail
18:24and next to it, a semicircular impression.
18:27It was part of the fossil once pronounced a jellyfish.
18:47At the bottom left, the imprint looked like the tip of an early crustacean.
18:50These three specimens identified as different organisms might all be parts of one animal Dr. Whittington ventured.
19:01The jellyfish-like fossil might be the mouth and the shrimp-like tail another appendage.
19:06At last, in 1991, a new animal carous fossil discovered at the Burgess Shale confirmed Dr. Whittington's theory.
19:22This fossil clearly showed two powerful arms growing out of the head as Whittington imagined,
19:27and eyes at the base of these spiny growths.
19:34On another fossil, a tail-like segment clearly emerged.
19:38After more than a century of speculation, a portrait of the fearsome animal carous came to light.
19:55Growing up to two feet long and flanked by 14 pairs of overlapping flaps,
20:01animal carous was the largest creature of the Cambrian period.
20:09The most baffling feature to Dr. Whittington was the round mouth with its circular array of teeth.
20:15What did it eat? And how could it capture its prey?
20:18Working with Dr. Whittington and his British colleagues to test their theories,
20:30the Japanese Broadcasting Corporation, NHK, constructed a model of animal carous for this television series.
20:38Is it possible to turn it upside down? Is it very delicate?
20:41Is it very delicate? Oh, I see, here's the other part.
20:44Oh, I'm curious, sir.
20:46Oh, this is the one that's...
20:48How the mouth functioned was of keen interest to all three men.
20:53Got it, uh...
20:55With its jagged plates that opened and closed like the iris of a camera lens,
21:00Whittington Briggs and Conway Morris believed this ancient hunter trapped and guillotined its prey.
21:06Would this animal carous replica leave the signature W-shaped scar on the trilobite models?
21:18Oh, bite, yeah.
21:20Yeah, it does.
21:22Yes, well, it still is the same shape of things.
21:26What it's done is spit away here, but the shape of the bite there is not very different from some of those.
21:33No, and it has this...
21:37I mean, it's a W-shape.
21:40Potential shape, that's right.
21:41Yeah.
21:43So it's certainly plausible.
21:45It is.
21:47What happens if you try it now?
21:49Like that.
21:50You can see now how you'd get a more substantial breaking away, rather like some of these here.
22:05The animal carous replica took a perfect W-shaped bite of the trilobite.
22:10Another piece of the Cambrian puzzle falls into place.
22:17Undulating its numerous flaps in wave-like motion, Dr. Whittington says this animal was highly maneuverable, traveling forwards and backwards with ease.
22:32Trolling the Cambrian seas, it preyed on mid-ocean and bottom-dwelling creatures with deadly accuracy.
22:43The evolution of stealthy hunters like animal carous may have been a contributing factor to the so-called Cambrian explosion.
22:58The eat-or-be-eaten struggle for survival prompted structural diversity.
23:03The five eyes on top of Opavinia's head were probably more useful for evading predators than searching for food.
23:13Once its enemies were spotted, Opavinia would dash to safety.
23:22Halusigenia and Wilwaxia sprouted sharp defensive spines.
23:26Escaping effectively was a necessary art, and many defensive swimming techniques were tested.
23:43Some animals developed fins at the base of their legs, allowing them to swim and walk.
23:49Fleeing predators, some moved sideways through the ocean.
24:01Others undulated up and down.
24:19Tiny animals that fed on smaller organisms tried to outwit larger predators.
24:33Sometimes burying themselves in the muddy ocean floor.
24:40To protect themselves and their offspring, the creatures of the Cambrian period tried on every possible anatomical costume.
24:47Yet few of these designs, including the formidable animal carous, would survive.
25:00Of all the sea life stalked by animal carous,
25:05Picaea, a tiny worm-like creature, somehow escaped extinction.
25:10This bit of an animal had no protective shell or defensive spines.
25:23But in the Cambrian period, one part of its design was wholly unique.
25:28As Conway Morris discovered, Picaea has a structure remarkably similar to a modern-day animal called Amphioxus.
25:40Both are equipped with a long, stiff rod running the length of the body, the notochord.
25:45The notochord.
25:50The notochord, which supported Picaea's muscle structure, is the design common to all vertebrates.
25:56This modest creature may be our earliest recognizable ancestor.
26:00Picaea, I believe, evolved into something like a fish, and from the fish, of course, we have the amphibians,
26:09represented, say, by the frogs and the salamanders, for instance, which invaded land in the Devonian.
26:15And then, after that, we have the reptiles and the mammals.
26:17So, perhaps, if Picaea had not survived, if it had gone extinct at some time,
26:24then, of course, ultimately there would have been no mammals and, of course, no humans.
26:36Though much about our lineage remains a mystery,
26:39the origins of the human backbone are linked to Picaea and its notochord.
26:43Few developments would lead to greater diversity.
26:54The reign of Anna Malocheris was not short-lived.
26:58It flourished for nearly 20 million years,
27:01a hundred times longer than the entire history of Homo sapiens.
27:05But in the evolutionary lottery, it was the lowly Picaea that survived,
27:16bearing offspring that would eventually populate the seas, the land, and the skies.
27:21California's Death Valley, one of the most arid regions in the world.
27:42Four hundred million years ago, an enormous river filled this valley, linking it to the distant sea.
27:57It was here that the fossils of the first fish to brave the freshwater habitat were found.
28:06It had taken them 60 million years to gain access to these estuaries.
28:13The man who discovered the fossil was Dr. David Elliott of Northern Arizona University, a specialist on ancient fish.
28:28The rocks have been slid.
28:29Tons of earth and sand formed sediments at this site,
28:37deposited by the river that ran through Death Valley eons ago.
28:44And it is here that Dr. Elliott has been focusing his excavation and research work on ancient freshwater pioneers.
28:51I can't really tell what that is.
28:55This is a teraspid. This is a lingulid.
28:59And lingulids are rather interesting because they are characteristic of estuarine environments.
29:04That is, environments in which fresh water and marine waters are mingling.
29:09These are areas of very high nutrients, where you may have large numbers of organisms coming to feed.
29:16And we have many teraspids here.
29:17There are also areas that many marine organisms can't get into.
29:23They're not able to survive in brackish conditions.
29:27And so it may be that teraspids were protected from some of their possible predators by living in these environments.
29:35Fresh water habitats have almost no salt content.
29:39A change in salinity can spell instant death for unacclimated marine life.
29:44This paramecium thrives in the salty medium of seawater.
29:50Breathing saline fluid, it regulates its mineral levels and ejects wastes.
29:59Salt-free water is added, changing the balance.
30:02In this unfamiliar hostile freshwater environment, the paramecium takes in water without voiding it, destroying the cell.
30:13The now bloated paramecium ruptures and dies.
30:19Taraspis is about eight inches long, its head covered with tough bony armor and its body with primitive scales.
30:37Unlike paramecium, taraspis managed to adjust to this new freshwater habitat with a little creative bioengineering.
30:47The taraspids' protective shell prevented water from penetrating the body through its outer layers.
31:03But the gills it used to breathe were a weak spot.
31:07To balance its system, taraspis developed a kidney powerful enough to pump extraneous water from its bloodstream.
31:19Transforming its physiology was a major evolutionary breakthrough for the first freshwater fish.
31:35But it was only a first step.
31:37400 million years ago, life on the river was unfolding.
31:53But the freshwater habitat posed new challenges.
31:57Rapid currents and waterfalls to negotiate.
32:07It took millions of years for marine life to adapt to these new ecosystems.
32:14To survive here, Earth's first fish would experiment with many anatomical designs.
32:27Meguasha Park lies on northeastern Canada's Gaspé Peninsula.
32:31400 million years ago, this was a tropical region situated directly under the equator.
32:48Etched in this meandering stretch of cliffs is the 20 million year history of fish evolution.
32:54Fossils of freshwater pioneers.
32:57Fossils of freshwater pioneers.
33:00Fish with fins to resist river current.
33:03Carnivorous fish with jaws and teeth.
33:06And a peculiar fish entirely different from any of the others.
33:13This fish had a backbone.
33:16Until now, they were fish with tough exoskeletons.
33:28But none with hard bone inside the body.
33:31Caerolepis, the earliest creature with a spine, appeared 390 million years ago.
33:37The most common fish today, the bony fishes, are its direct descendants.
33:50Like modern fish, Caerolepis was equipped with one pair each of pelvic and pectoral fins.
33:56It was sleek, with jaws and sharp teeth for catching prey.
34:13Acquiring a spine, Caerolepis developed strong muscles to swim with speed and power.
34:19But there were other agile swimmers in the river that had managed to do without one.
34:29Why, then, did the backbone develop?
34:36While the sea was rich in minerals essential to life, the river was in short supply.
34:46This is heart tissue.
34:55Working in unison, these cells allow the heart to pump blood throughout the body.
35:05To function properly, the heart needs calcium.
35:10Calcium concentration in a river is in perpetual flux.
35:24When levels are high, calcium is stored as bone.
35:28When they're low, the bone reservoir supplies the necessary mineral,
35:32regardless of external conditions.
35:34Meanwhile, the seemingly solid bone is constantly being replenished.
35:49At the top of the screen, hard bone is visible,
35:53moving below our cells that dissolve it.
35:55Once the bone is dissolved, calcium circulates through the bloodstream to every part of the body.
36:07The fate of ancient fish rests on a simple backbone.
36:20Those without eventually perished from calcium deficiency,
36:25or returned to their native sea.
36:28For many years, Cairo Lepis reigned as the king of freshwater fish.
36:34His anatomy gained him independence from the marine world.
36:42Today, the descendants of Cairo Lepis thrive in both fresh and saltwater habitats.
36:47The river was a proving ground for the earliest fish and their offspring.
36:57And in this new habitat, they gradually adapted the body system's key to survival on land.
37:03Another fish with a backbone appeared on the river at about the time of Cairo Lepis.
37:18It was called Eusthenopteron, a bottom dweller.
37:25Eusthenopteron was not an efficient swimmer like many fish,
37:28but it had secured an evolutionary niche with powerful bony fins
37:34to push its way through the river's undergrowth.
37:39This fish was a stealthy hunter poised for action.
37:53Eusthenopteron's habitat shaped its unusual bone structure.
37:58which would one day lead to the evolution of terrestrial animals.
38:10South America's Amazon breeds acres of jungle swampland,
38:15mimicking conditions in the age of Eusthenopteron.
38:21And with the swamps, a host of unusual life forms.
38:29Among them, the lungfish, a mud-dwelling creature.
38:37This fish has gills, but it also has lungs for breathing air.
38:46In such murky water, oxygen content is often very low.
38:50The lungfish probably developed lungs to breathe oxygen from the air
39:00when the supply in the water was depleted.
39:02Just as his ancestor Eusthenopteron had done eons before.
39:13Poking its head above the surface for a life-sustaining breath,
39:20Eusthenopteron surely caught a glimpse of the world above the waterline.
39:24Now that fish had evolved kidneys, bone, and lungs,
39:31land was almost within reach.
39:33The first four-legged creature appeared ten million years after Eusthenopteron.
39:47Its remains discovered in a forest in Scotland.
39:56At the time, this region resembled today's Amazonian swampland.
40:00Dr. Per Eric Allberg of the British Natural History Museum
40:11has been studying the earliest tetrapods.
40:16He's trying to find out how and why limbs evolved from fins.
40:21Only ten fossil pieces have been discovered to date.
40:31But even from these few specimens,
40:34an image of this new creature is emerging.
40:39Almost five feet long,
40:41it looks like today's giant salamander.
40:46I suspect that the reason why limbs evolved
40:48was because these animals were living in very shallow water.
40:52And limbs can be rather better than fins for moving in those sort of conditions,
40:57even if you're not really moving onto land.
41:01These earliest tetrapods with limbs rather than paired fins
41:06still have gills, tail fins, and other features
41:10which suggest that they were very much aquatic animals.
41:12So I don't really believe that they were using the lakes
41:15for walking purposefully over land.
41:16They might have made short excursions over land,
41:19but more probably they were using those limbs in shallow water.
41:24Today's giant salamander still spends most of its time in the water.
41:29Negotiating the shallows is a matter of walking, not swimming.
41:33Even in swift currents, the salamander plants its feet on the river bottom
41:44and moves around with ease, aided by its natural buoyancy.
41:48To move as fluidly on land, the salamander would require a far sturdier skeletal structure.
41:58360 million years ago, the once barren earth lay under a canopy of green.
42:10Giant forests thrived, and small insects now burrowed in the shady wetlands and soil.
42:21This landscape was ready to support new life.
42:24But to take their first step on land, our ancestors had one more obstacle to overcome.
42:35Gravity.
42:36This is Ichthyostega, an animal that surfaced 10 million years after the earliest four-legged creatures.
42:48Judging from the size of his skull, Ichthyostega measured nearly four feet long.
43:00Its backbone and hind legs clearly defined.
43:04But this animal also had thick finger bones and a sturdy skeletal structure.
43:10Scientists conclude this was the first creature to walk on land.
43:18For the first time, an animal with a supporting skeleton around its backbone.
43:25The ribcage protected vital organs like the heart and lungs.
43:30On land, without the buoyancy of water to cushion them,
43:34these organs would be crushed by the animal's weight.
43:39By developing ribs, Ichthyostega emerged in a body that could withstand earth's gravity
43:45and move about freely over land.
43:53At long last, the time had come to look beyond the water's edge.
43:57A hundred million years had passed since the earliest fish ventured from the ocean into fresh water.
44:10A habitat that helped shape the complex body systems necessary for life on land.
44:24Bolstered by millions of years of evolutionary advancement, Ichthyostega took its first steps while an ocean of life swam in its bones.
44:42From sea to river, and from river to land, life had taken leaps of astonishing complexity.
44:56There is no way to know what called Ichthyostega from the relative comfort of the river toward the challenges that awaited on land.
45:06But in taking its first steps, Ichthyostega blazed a new tram.
45:13A path we too would forge on our own evolutionary journey from the nurturing seas into the great unknown.
45:22I don't know.
45:52I don't think so, yet I don't think so, yet I'm the person can?
46:05I think so, but I'm wherever I want to wish you something to meet yourself that day came to me.
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