Documentary, Evolutions - Ep 1 The Whale With Legs 2008
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00:0050 million years ago, a hungry land animal seeks a new source of food.
00:11This sets him on a spectacular evolutionary journey and on a collision course with rivals.
00:21Today, this creature looks like a fish, but it retains key traits from its terrestrial past.
00:32It's warm-blooded, a mammal, and it breathes air through its lungs.
00:43How did a creature built for land become master of the oceans?
00:51Asia. Pakistan. The Suleman Mountain Range.
01:21This rocky terrain was once the bed of the ancient Tethys Sea.
01:26Locked away in this rock are secrets of ancient marine life and death.
01:35In 1978, a team of fossil hunters from Michigan set to work.
01:53Palaeontologists are time travelers.
02:02They visit the ancient past by digging into the earth.
02:09Each layer of rock is like a time capsule, recording major events in the planet's history.
02:27Asteroids. Natural disasters. Climate change.
02:39It's all recorded in layers of rock. Planet Earth's DNA.
02:46A team member cracks open a rock.
02:51A team member cracks open a rock.
02:55Inside is a fossil, unlike anything they've seen before.
03:05This fossil sets one man on a voyage of discovery.
03:18The expedition leader was Philip Gingrich.
03:23In the University of Michigan vaults, he examines his amazing find.
03:31It's the partial skull of a mammal that lived 50 million years ago.
03:37In 1978, Gingrich couldn't work out which family of animals it belonged to.
03:45When we found it, when we cleaned it, I really wasn't sure what it is.
03:56I was a specialist of land mammals.
04:00And it didn't look like anything I knew.
04:11Gingrich commissioned experts in mammal anatomy to reconstruct its skull.
04:30Gives you an idea of what the whole skull might have looked like.
04:36This is real and this is reconstructed.
04:38But it's reconstructed following the plan of a typical mammal.
04:53Later digs uncover more crucial pieces of the skeletal jigsaw.
05:00Finally, this enigmatic animal comes to life.
05:11I think it would have four limbs.
05:15I expect probably it had short hair.
05:19And they still have hooves.
05:21If we think it's a land animal, we'd expect it to look wolf-like.
05:25But Gingrich still couldn't identify which order of animals it belongs to.
05:40Then he spots a tiny S-shaped bone in the ear region.
05:44He finds out that this bone is known as a sigmoid process.
05:52And it's unique to one order of animals that today lives in the water.
05:57Gingrich finally realized what this creature is.
06:07It's something primitive.
06:08It's something transitional.
06:10But nonetheless, with the sigmoid process, a primitive whale.
06:15This can only mean one thing.
06:26The modern whale began life as a land animal.
06:31To find out how a land animal evolved into the modern whale, we must return to ancient Pakistan.
06:44This is the ground the creature walked on 50 million years ago.
07:07The world then is a hotter place.
07:09In the region that is now Pakistan, higher temperatures likely created an arid environment.
07:22The whale's ancient ancestor, named Pachycetus, faces a survival crisis.
07:40The whale's ancient ancestor, named Pachycetus, faces a survival crisis.
07:52It's the shape, size and weight of a modern wolf.
08:01And lives on a diet of plants and small animals.
08:08But climate change is wiping out his food supplies.
08:15He needs to find a new food source, and quickly.
08:22The ancient whale takes its first tentative steps into water.
08:23The ancient whale takes its first tentative steps into water.
08:27It's an extraordinary gamble.
08:28What rewards did the water get?
08:29It's an extraordinary gamble.
08:30What rewards did the water get?
08:32What rewards did the waters hold for Pachycetus?
08:33The answer lies.
08:34It's an extraordinary gamble.
08:37What rewards did the waters hold for Pachycetus?
08:38The answer lies in the earth itself.
08:39It's an extraordinary gamble.
08:40What rewards did the waters hold for Pachycetus?
08:42The answer lies in the earth itself.
08:43It's an extraordinary gamble.
08:44It's an extraordinary gamble.
08:49It's an extraordinary gamble.
08:53It's an extraordinary gamble.
08:55What rewards did the waters hold for Pachycetus?
09:00The answer lies in the earth itself.
09:0350 million years ago, the landmasses of planet earth drift further apart.
09:19This creates new ocean currents.
09:26These currents convey warm water and air from the equator to the polar regions.
09:35Warmer poles mean a warmer planet.
09:43Hotter temperatures can boost photosynthesis, producing an abundance of marine life.
09:52Pachycetus finds a banquet of food in these shallow waters.
09:59I think they probably started as scavengers, running along a strand line, feeding on dead fish
10:07that washed up on the shore.
10:12And once you're in the water feeding on dying fish, it's a logical step to try to catch other fish.
10:22Just as Pachycetus solves one crisis, food, it faces another, predators.
10:36To swim, Pachycetus has to paddle like a dog.
10:42It's a poor design, making him a slow and clumsy swimmer.
10:47I will try to catch the soldiers finally put them back.
10:51Yeah just as Pachycetus can draw.
10:58But where does it take to pair for that?
11:01believed in some waves for both shores,
11:03which arte kajuic in between the northats,
11:07so it's not what levar away to seaess.
11:09But it was the last castle remains in the cave.
11:12It's about the fog.
11:12He Kapila's not careful.
11:13Pachycetus
11:43The next mystery is what happened after Pachycetus?
11:57How did this land animal evolve to become king of the oceans?
12:13Fifteen million years ago, the whale ancestor, a land mammal named Pachycetus, disappears from the fossil record.
12:26In 1994, 16 years after Philip Gingrich discovered the remains of Pachycetus, one of his former students makes the trip to the same region of Pakistan.
12:50Hans Fuesen is seeking ancient land animals.
12:58His quest will pay off beyond his wildest hopes.
13:08In rock dating back 49 million years, he discovers the bones of an unknown creature.
13:20The first day we found a hind limb.
13:25The next day we found some vertebrae and some ribs.
13:32And the third day we finally found a skull.
13:38And I still didn't know what it was.
13:39Bafflingly, this creature appears to have legs like a land animal, but feet like waders.
13:51I got very frustrated with the fossil having this beautiful skeleton and not knowing which animal this was.
14:13Then he spots a bone unique to one order of animals living today.
14:17And then it struck me.
14:22This is an ear bone.
14:25And it's the ear bone of a whale.
14:29That finally made the penny drop.
14:34And I realized that now we finally found this amazing skeleton.
14:39This transitional whale, a whale with legs.
14:50It struck me that we caught evolution in the egg here.
14:53This is why Pachycetus disappeared.
15:10It had simply evolved into a new species.
15:14Poor swimming skills made Pachycetus vulnerable.
15:17So it adapts in three key ways to swim better.
15:21His tail develops muscles and flattens like that of an otter.
15:30His back legs shorten and widen to act like flippers.
15:35He becomes more streamlined.
15:46Pachycetus.
15:48Pachycetus.
15:50Pachycetus.
15:52Pachycetus.
15:54Pachycetus.
15:55Pachycetus.
15:58Some time in the ancient past, a whale ancestor evolved the skills to live permanently in the oceans.
16:10Pachycetus.
16:12Pachycetus.
16:14Pachycetus.
16:16Pachycetus.
16:18Pachycetus.
16:20Pachycetus.
16:21Pachycetus.
16:22Pachycetus.
16:24Pachycetus.
16:25Pachycetus.
16:26Pachycetus.
16:27Pachycetus.
16:28Pachycetus.
16:29Pachycetus.
16:30Pachycetus.
16:31Pachycetus.
16:32Pachycetus.
16:33Pachycetus.
16:34Pachycetus.
16:35Pachycetus.
16:36Pachycetus.
16:37Pachycetus.
16:38Pachycetus.
16:39Pachycetus.
16:40Pachycetus.
16:41Pachycetus.
16:42Pachycetus.
16:43Pachycetus.
16:44Pachycetus.
16:45Pachycetus.
16:46When you're studying teeth, you really get a good idea of lots of different aspects of
17:04the life of the animal, such as its diet, where they were living in water on land, and
17:12which waters they were drinking.
17:15Thuisen expects the teeth to show Ambulocetus lived in the ocean.
17:24But the results are a surprise.
17:28They reveal that Ambulocetus drank fresh water.
17:33It had to stay close to rivers and lakes.
17:41This whale ancestor still lives primarily on land.
17:46We were surprised because modern whales can drink seawater.
17:52Their ancestors were land mammals and therefore fresh water drinkers.
17:56Somewhere that transition had to happen, moving from fresh to sea.
18:01But it hadn't happened 49 million years ago.
18:05And this raises an intriguing question.
18:10What prevents Ambulocetus from fulfilling the whale's destiny of life in the ocean?
18:1750 million years ago, the whale is a wolf-like land creature that hunts in shallow waters.
18:32One million years later, it evolves three key features to swim better.
18:41A stronger tail, wider rear legs, wider rear legs, and a more streamlined body.
18:54Despite being more aquatic than its predecessor, tests show that Ambulocetus, or the walking and swimming whale, lived mostly on land.
19:07To find out why, Thuison returns to the skeleton.
19:22It's a complete Ambulocetus based on the one he found, and it gives away a surprising secret.
19:32This species has a large head and body, but relatively small hind legs.
19:41This can mean only one thing.
19:44I think in Water Ambulocetus wasn't a very strong swimmer.
19:48It certainly couldn't pursue fish because the fish would be much faster than him.
19:54We think that it was a predator.
19:56It would probably hang out in shallow water, sort of hidden,
20:00and waited for prey to come up to it and then would lunge to catch them.
20:0649 million years ago, this poor swimmer faces grave danger, hunting even in shallow seawater.
20:16If you look at the shallow marine fauna of that time, there are lots of big predators, such as big sharks, much bigger than the whales.
20:24They would certainly have been eaten and would have competition from crocodiles and sharks if they were hunting prey.
20:34was it safer on land?
20:48Was it safer on land?
21:03I think Amylcetus would have been pretty clumsy on land.
21:05It would have been similar to a sea lion or maybe a crocodile.
21:10They would have been slow, lumbering,
21:12and mostly with their bellies on the ground
21:15as they were resting on land.
21:18Poor in both land and marine habitats.
21:2449 million years ago,
21:27Ambulocetus vanishes from the fossil record.
21:38The mystery of whale evolution deepens.
21:42When and how did the ancient whale evolve to live full-time in salt water?
21:52What is the secret to its transformation from clumsy land animal to master of the high seas?
22:05In 1994, Philip Gingrich, from Michigan, returns to the Suleman mountain range in Pakistan.
22:20It was here, 16 years earlier, he unearthed the oldest whale ancestor.
22:37His quest now is to find the first ancient whale that lived permanently in the sea.
22:42They're extraterrestrial in the sense that they left the earth, they left the land, and live in the sea today,
22:50which is a little like outer space, really.
22:52The question is, can he now hook the biggest fish of all, the first fully aquatic whale?
23:04The rock here once formed the bed of the ancient Tethys Sea.
23:12The region is rich in ancient marine fossils, but remote.
23:17They must complete the journey on foot and camp.
23:25They set to work using only tools they can carry in a backpack, hammers, trowels, and brushes.
23:36The team discovers the skeleton of another ancient whale.
23:42The question is, could this species be the elusive missing link that cut its ties with fresh water?
23:57Back at the University of Michigan, they set to work, separating clean bone from mineral.
24:12Tests on the mineral rock reveal this creature lived 46 million years ago, three million years after Ambulucetus.
24:34Ambulucetus was a poor swimmer, struggling to escape predators or to hunt.
24:39This species has evolved a series of adaptations to swim better.
24:51He has a shorter, more powerful neck, better for diving.
24:56His rear legs widen, and become more flipper-like.
25:03His tail develops muscles.
25:08However, the teeth of this ancient whale reveal something far more significant.
25:17Just four million years after the whale ancestor, Pachycetus, first entered fresh water.
25:32This whale lives permanently in the sea.
25:36This is the first whale that really took to the sea, and to be honest, we didn't believe it.
25:47The secret to its success and the survival of the entire whale species comes down to a tiny but ingenious device inside its trademark ear.
25:58Paleontologist Philip Gingrich has unearthed a whale that lived 46 million years ago.
26:13He names it Rhodocetus.
26:21It appears to be the missing link between the wolf-like ancient whale, its descendants,
26:32and modern whales.
26:43Inside Rhodocetus is the key to an age-old mystery.
26:50How did the ancient whale, a land animal, adapt to survive in the ocean?
27:01There are few clues in its skeleton.
27:05It's three meters long and similar to Ambulocetus, the ancestor that three million years earlier
27:13had only been able to drink fresh water.
27:18Now this new species lives in the oceans and radiates throughout the globe.
27:28How has it adapted to this salty new world?
27:33And why don't vicious marine predators wipe it out?
27:38This becomes one of the single greatest mysteries of whale evolution.
27:50To understand Rhodocetus, we must first understand the world it lives in.
27:58Forty-six million years ago, India is separate from the landmass of Eurasia.
28:05The Tethys Sea lies between.
28:11Over tens of millions of years, India moves closer to Eurasia.
28:20As the Tethys Sea narrows, it becomes more shallow.
28:33Now, the climate plays a role.
28:36In a shallow sea, it's highly productive because you've got a lot of light coming in,
28:43a lot of microorganisms processing the nutrients.
28:49And there's a lot there for fish to feed on.
28:55And of course, if there are a lot of fish,
28:57there's something there for mammals to go in and feed on.
29:02For species quick enough to exploit it,
29:04the Tethys Sea is a marine garden of Eden.
29:12Rhodocetus feels an irresistible evolutionary pull into the sea.
29:20The reward is straightforward.
29:22More food.
29:23Evolution modifies an existing organ to process salt water.
29:37His kidneys filter out the salt from the sea water,
29:41which he then excretes through his urine.
29:47Rhodocetus finds the subterranean world brimful in life.
29:53But not all of it is dinner.
30:04Fearsome predators stalk the Tethys Sea.
30:09For sharks and crocodiles, ancient whales have proven easy meat in the past.
30:14To survive, Rhodocetus must find a way to escape predators.
30:27The key to how this ancient whale survives in the ocean
30:31is hidden inside its most distinctive feature,
30:34the ear.
30:41Professor Fred Spohr studies a vital organ
30:44situated inside the inner ear of just about every creature.
30:52Called the organ of balance,
30:54it is key to the survival of Rhodocetus.
30:56The organ of balance inside the inner ear is an absolutely vital, a key organ
31:04to function for any animal.
31:08Whether you're a fish or a frog or a whale.
31:14It's an organ that makes you aware, conscious or subconscious,
31:18whether you're moving, and it helps you to keep your balance and not fall over.
31:22To understand what saves the ancient whale,
31:36Spohr produces a model of a human inner ear, enlarged 12 times.
31:41The organ of balance consists of three canals at right angles, filled with fluid.
31:56The fluid moves when the head moves.
31:59Nerve cells register these fluid movements and send signals to the brain.
32:04The brain instantly decodes these signals and adjusts our balance so we don't fall over.
32:11However, acrobatic behaviour causes the liquid in our inner ear to slosh about.
32:21Sending scrambled messages to the brain.
32:24This causes dizziness.
32:29The inner ear controls balance.
32:34But how did it tilt the balance of survival in favour of the ancient whale?
32:38Spohr finds the answer when he compares this human ear to that of the whale.
32:49If we now, for comparison, actually look at the inner ear of a whale,
32:54that has also been enlarged 12 times,
32:56then we can see that there's not that much overall difference in size.
33:00Even though whales are, of course, much larger than humans are.
33:04However, the enormous difference is that the bit that deals with balance,
33:09here and here, is enormously reduced in the whale.
33:14The whale's inner ear is so small that the liquid inside barely moves.
33:26This allows them to turn and twist at high speed without getting disorientated.
33:31Some 45 million years ago, the ancient whale's organ of balance was shrinking.
33:45And for good reason.
33:59It makes him agile enough to outmaneuver predators.
34:04Rhodocetus survives and continues to evolve.
34:18But its descendants are about to face dramatic climate change and a terrifying new predator.
34:34It's about to face dramatic climate change.
34:44Egypt.
34:46The western desert.
34:50150 kilometres south-west of Cairo.
34:55These parched sands.
34:58Harbour secrets.
34:59More ancient than the pyramids.
35:01Philip Gingrich has been excavating this site since 1983.
35:08In that time, he's unearthed 400 giant whale skeletons.
35:14These ancient whales are so large, they're named basilosaurus, which means king lizard.
35:22But what are these whales doing in the desert?
35:28Of course, the whales didn't really live in the desert.
35:30This was all a shallow sea before.
35:33And one that was full of sunlight, clear water, teeming with life, including archaic fossil whales.
35:43It's an 18-meter-long, 50-foot-long whale that you simply can't miss.
35:50Being so large, there's no doubt that basilosaurus was the top carnivore, the top predator in this
35:58ecosystem.
35:59The equivalent, if you will, of T-rex farther back in the past.
36:0839 million years ago, this is the bed of the ancient Tethys Sea.
36:13By now, basilosaurus thrives in oceans and seas all over the globe.
36:2240 million years ago, this is the bed of the ancient Tethys Sea, especially in the food-rich waters of the Tethys Sea.
36:3440 million years ago, basilosaurus has evolved a set of impressive tools for hunting.
36:45Exceptional eyesight.
36:48Improved underwater hearing.
36:50It evolves its long, thin body shape to hunt in shallow waters.
36:57And from its terrestrial past,
37:01it retains two useless remnants.
37:04The most interesting thing about basilosaurus is the retention of hind limbs with all the bones
37:12right down to the tips of the toes. So they are a vestige of a former life on land.
37:25Basilosaurus weighs in at a massive 6,300 kilos.
37:29It's change in size turns it from the hunted into the hunter.
37:37Now the tables are turned on an old foe.
37:46The shark.
37:59Sharing the waters of the Tethys Sea with basilosaurus is a smaller, more vulnerable whale species.
38:13The Duradon whale most resembles a modern dolphin.
38:20It has a powerful vertebral column and short, flipper-shaped forelimbs.
38:25And like the modern dolphin, it has a tail fluke.
38:31However, at just five meters long, it's much smaller than basilosaurus.
38:41There's even some evidence that basilosaurus preyed on young, if not adult, Duradon.
38:48One theory is that to protect themselves from predators, Duradon whales swim in pods.
39:00Only one of these two species will survive to become ancestor to the modern whale.
39:07But which will it be?
39:09The small, hunted Duradon?
39:10Or its massive predator, basilosaurus?
39:20Whale evolution spawns its next great unexpected twist.
39:31Fossil records show that 36 million years ago, the mighty basilosaurus dies out.
39:41The question is, why?
39:47Gingrich has been scratching away at this conundrum for many years.
39:55To the clues to the mystery lie beneath the sands of the western desert.
39:59Gingrich believes that basilosaurus evolved its eel-like body to hunt in shallow waters.
40:14Its body shape is perfect for hunting in bays like this one.
40:17But is it a victim of its own adaptation?
40:3635 million years ago, planet Earth is changing dramatically.
40:41The ocean is changing dramatically.
40:45Oceans continue to cool.
40:48Antarctica has split from South America and develops a permanent ice cap.
41:02Water that once flowed down into the oceans remains frozen at the poles.
41:07This causes a dramatic drop in global sea levels.
41:17Shallow coastal waters disappear, forcing basilosaurus to hunt in deeper waters.
41:28Its eel-like body struggles in this deeper water.
41:31It lacks the power to dive.
41:40Maybe it's only good for living in surface water.
41:42Maybe once you need to dive to get food, it wasn't so good anymore.
41:47Short and muscular, the Dorodon has no such problems.
41:56This is the whale species left to inherit the Earth.
42:02I would think that the success of Dorodon
42:07depended on its conservative body proportions.
42:10Dorodon survives, but the future of the whale species is in grave danger.
42:30Later, ancient whales face what many consider the most terrifying predator in history.
42:36A predator so big that each one of its teeth is the size of a man's hand.
42:50A further dramatic twist in the journey of the modern whale takes place 30 million years ago.
43:07In the cooler seas of the mid-Atlantic, the ancient whale is five meters long.
43:21And dwarfed by a terrifying new predator.
43:29Monster sharks.
43:30Weighing in at 40,000 kilos and over 60 meters in length,
43:39the megalodon shark's mouth is so large a human could stand upright inside it.
43:49Even whales aren't safe from such a fearsome predator.
44:00Megalodon stops dead in his tracks.
44:12Unwittingly, ancient whales have stumbled upon a sure-fire way for their species to flourish
44:19for millions of years.
44:20To escape, they've headed away from the equator towards the new, chillier polar seas.
44:36Thanks to their warm blood, they can handle the cold water.
44:40But their predator can't.
44:48Sharks are cold-blooded.
44:51Their body temperature is the same as the waters in which they live.
44:55In colder water, their bodies can shut down.
45:01Megalodon was tied to a warmer sea and didn't survive this new, cold world.
45:11These polar waters are safe from megalodon and rich in food supplies.
45:17But the whales' problems are far from over.
45:23Visibility in these deep polar waters is poor.
45:28Somehow they must find a way to catch prey they can't see.
45:32The ancient whale must develop the most sophisticated marine tools in the natural world.
45:48Evolution arms predatory-toothed whales with a high-tech device to hunt.
45:55Sonar.
46:02They emit a focused beam of high frequency clicks.
46:08The sound bounces off any object in its path.
46:12The whale can decode the returning echo and determine the size, shape and speed of the object.
46:18The whale uses this to pinpoint and then swoop on shoals of fish.
46:35But how do they adapt to hunt in deeper waters?
46:38Whales can control the flow of blood to their hearts and brains.
46:50As a result, they don't suffer a lack of oxygen on deep dives.
46:56Modern sperm whales can dive over a mile down and stay below for two hours.
47:03Baleen whales evolve a digestive system to suit seasonal migrations.
47:13They can build up enough blubber to go without food for several weeks.
47:22This leaves them free to engage in typical mammal behaviour.
47:26Like mating, socialising and showing off.
47:37Especially the most expressive member of the whale family.
47:41Dolphins.
47:42Dolphins and porpoises are big-brained relative to their body size.
47:50They're very personable if you ever meet them face to face.
47:54You have a sense that there's a sentient being there that reminds us of ourselves, I think.
48:03Today there are over 80 whale species.
48:07The largest is the blue whale.
48:09It has a heart the size of a Volkswagen Beetle.
48:13And a tongue the size and weight of an African elephant.
48:22Other whales have evolved incredible survival skills.
48:30The grey whale can swim 20,000 kilometres in an annual migration.
48:39Orcas can reach speeds of 55 kilometres per hour.
48:45And the bowhead whales can live for over 200 years.
48:51The journey the whale has made to get this far is truly amazing.
48:55From its wolf-like ancestor, its struggles between land and water.
49:10Before finally adapting to the ocean.
49:12It's like the Rosetta Stone for evolution.
49:25A lot of textbooks use the whale as their example for evolution.
49:31Because it's now so well documented.
49:32I like it because it's big.
49:38And I like it because it's backwards.
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