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00:01The dinosaurs had a long and glorious reign, but it was not to last.
00:10And with their passing, a land of opportunity was laid bare for the little mammals that had scampered about their feet.
00:21They were quick to evolve to exploit every available niche.
00:25From reptile-like egg layers, to pouched hovers, rodents, to rhinos, bats, to whales.
00:39All driven by competition and their place on the food chain.
00:45Leading to the stunning diversity of animals we enjoy today.
00:50And the start of our own dramatic story on Earth.
01:02Rewind to 325 million years ago.
01:05The reptiles split into several groups.
01:22The Diapsids, the great granddaddies of crocodiles and birds, gave rise to their bigger cousins.
01:28Their bigger cousins.
01:34The age of dinosaurs had begun.
01:46The climate warmed, plants flourished, and on them dinosaurs got huge.
01:51The earliest proto-mammals skulked in their shadows.
02:11But rather than compete, a silent revolution was going on right under the dinosaur's noses.
02:24The earliest known true mammals, dating back more than 200 million years, like Morganocodon, looked superficially like modern sharks.
02:29Shrews, though were still primitive.
02:30Though not getting bigger, the mammalian pioneers were going through some radical changes.
02:36Already, like the dinosaurs, they walked with their legs.
02:39under their bodies.
02:40This required a lot of energy, and might have fueled the development of warm bloodedness.
02:41This required a lot of energy, and might have fueled the development of warm bloodedness.
02:47Though not getting bigger, the mammalian pioneers were going through some radical changes.
02:55Already, like the dinosaurs, they walked with their legs under their bodies.
03:01This required a lot of energy and might have fueled the development of warm-bloodedness.
03:09And they were hairy, the fur helping to insulate them.
03:16Their jaws became stronger and teeth started to vary in shape.
03:23The start of the incisors, molars and canines we know today, the cutting edge of chewing efficiency.
03:34And these changes separated the jaw from other small bones that gradually became the tiny bones inside our ears.
03:42This gave mammals unparalleled hearing, especially higher frequencies.
03:49We were developing a unique skill set that would forever set us apart.
03:56But it would be a while before we could show off our talents.
04:03The dinosaurs stole the show.
04:06But while they ruled, mammals diversified.
04:15The dinosaurs might have done us a favor.
04:19Driving mammals to exploit new niches.
04:22Forcing them to come out under the cover of darkness.
04:25Being active at night might have encouraged our heightened senses.
04:32Though most were smaller than cats, their adaptability was huge, moving into every major habitat on Earth.
04:41Some were tree climbers, looking something like modern honey possums.
04:51In the canopy above, Vilavolodon glided between branches.
04:58It's long gone, but resembled the sugar glider.
05:04It's long gone, but resembled the sugar glider.
05:13Docofossa was a digger like a modern mole rat.
05:16And Castoracorda took to the water like a beaver.
05:30These first mammals took advantage of every resource.
05:37There were even a few that ate baby dinosaurs.
05:40During the Cretaceous, the last chapter for the dinosaurs, flowering plants and the first grasses appeared.
05:56And hot on their heels, pollinating insects grew in abundance.
05:59Dinosaurs grew huge on the plant diets.
06:15But with their specialized teeth, the mammals were perfect insect munchers.
06:22And they flourished.
06:29The dinosaurs might have been the rulers, but the mammals were a growing force.
06:49Mammals are united by being warm-blooded, having big brains, producing milk for their young, walking on upright legs, having specialized teeth,
06:59and heightened senses of smell and hearing.
07:13But there was much variation, and many different groups.
07:16The earliest mammals were egg layers, a trait carried into the modern age by only one small family of mammals.
07:37These bizarrely unique animals first appeared more than 100 million years ago, the oldest of the modern mammal groups.
07:44Even the early representatives looked like modern platypus.
07:56They're relatively primitive mammals, as they still lay rubbery eggs like lizards.
08:01And though they do produce milk, they don't have nipples.
08:05The milk oozes from modified sweat glands.
08:07They weren't the most advanced, but through their semi-aquatic lifestyles, the pioneers didn't have to compete with the more advanced mammals evolving around them.
08:23The platypus has only one cousin, the echidna, which evolved from platypus tens of millions of years later.
08:43A game, carving out a unique specialism as a prickly eater of ants and termites, so it could avoid too much competition.
08:52Together, they form a unique group of mammals, the monotremes.
09:02Together they form a unique group of mammals, the monotremes.
09:05It's not a very glamorous name.
09:10Monotremes means one whole, because they have just one opening for urine, feces and breeding.
09:18A leftover from reptile ancestors, and something that all other mammals would leave behind.
09:26Each mammalian group would put its own twist on the basic design, finding a niche to thrive alongside the dinosaurs.
09:45But the good times were not to last.
09:47When the meteor struck, bringing doom to the dinosaurs, many of the mammal groups shared their fate.
10:17But because they were small, warm-blooded and adaptable, some of our ancestors were able to hide away in caves and burrows.
10:38And when the dust settled, they were ready to take over the planet.
10:47The survivors were not the specialists who couldn't adapt to change, but the generalists, omnivores, best suited to eking out a living during the post-apocalyptic world.
11:08There were at least ten mammal groups, but of the three modern mammals, it was the marsupials that dominated the scene.
11:17The oldest known marsupial fossil dates back 125 million years, so these are vintage mammals.
11:40The oldest known marsupial mammals.
11:47Unlike earlier proto-mammals, they don't lay eggs anymore.
11:53Rather than shell, there's something like a yolk sac to feed the embryo in its mother's womb, briefly.
12:02After a few short weeks, a baby, known as a joey, is born.
12:06Even the biggest marsupials have tiny, premature babies, smaller than your little finger.
12:15The only parts of these babies that are well-developed are the front limbs, so the little one can follow instinct and haul itself into its mother's pouch and its mouth,
12:21so that once it gets there, it can latch onto a teat and start sucking.
12:22The only parts of these babies that are well-developed are the front limbs, so the little one can follow instinct and haul itself into its mother's pouch and its mouth, so that once it gets there, it can latch onto a teat and start sucking.
12:39So, unlike the placental mammals like us, that evolved later, the marsupials effectively give birth to premature embryos and finish off their development on the outside instead of inside, protected in the pouch.
13:03When they evolved 125 million years ago, the earth still had one giant landmass, Pangea.
13:28Marsupials appear in the fossil record in both North America and China first, but gradually spread out over most of the globe.
13:43Today, they are mostly associated with Australia, but actually, that was the last place they inhabited.
13:58Not long after marsupials spread, Pangea broke apart, with Laurasia, the giant continent of the north, that would later split into Europe, Asia and North America being the marsupials realm.
14:24The continents were ever shifting, and sometime around the end of the dinosaur era, a land bridge was formed between the Americas and marsupials spread into Gondwana in what is now South America.
14:49Here they rapidly spread and diversified.
14:53Here they rapidly spread and diversified.
14:56Some time after that, just a single species of small, mouse-like, tree-climbing marsupials made their way across the joint continent of Antarctica and landed in Australia.
15:15All of the Australian marsupials evolved from this one little pioneer.
15:22From this one little pioneer.
15:35Today, 70% of marsupials live in Australia and surrounding islands.
15:41The rest, the rest, like the opossums, live in the southern Americas.
15:48Most are small, nocturnal climbers adapted to a wide range of diets.
15:56Insects.
15:59Nectar.
16:00Nectar.
16:03Leaves or meat.
16:06Because they occupy the same niches as placental mammals, they often look alike, though are not related.
16:12Because they occupy the same niches as placental mammals, they often look alike, though are
16:20not related.
16:23Many look like small rodents.
16:35Koalas are like eucalyptus munching sloths, making their living in the canopy.
16:56And instead of deer and antelope, the open plains are occupied by other fleet-footed grazers.
17:05Kangaroos.
17:11They are the largest marsupials today, but in the past, there were giants to rival the
17:17bigger placentals, like wombats the size of mastodons.
17:33But Australia was to become an ark.
17:42Marsupials lost their starring role in animal communities in other parts of the world.
17:53The reign of the marsupials was hard hit by the dino-dooming meteor.
18:04It's unclear whether placentals had fully developed by this time, or whether their ancestors were
18:09just waiting in the wings.
18:15But either way, within a few million years, they were the new kids on the block.
18:23They had the upper hand for claiming the main stage.
18:29They had higher metabolisms, bigger brains, and could reproduce faster.
18:40And of course, the namesake difference.
18:53Placentals have a placenta that nourishes the embryo in the womb, allowing it to develop longer
18:59before birth and shortening the weaning period after birth, which seems to have removed the limits
19:06of mammal diversification that was holding the marsupials back.
19:16The meteor was like the starter's pistol, and placental mammals were barely off the block when they started
19:22to separate into some very different, distinct groups that would all race to diversify.
19:36Perhaps the most primitive are the xenothrins, some of the oddities of the animal kingdom.
19:45Probably starting out as small burrowing animals, they were fast-trapped to great things.
19:57At the height of their success, there were armadillos the size of cars.
20:05And ground sloths, as big as elephants.
20:17The only representatives that made it to the present are much smaller, but no less extraordinary.
20:23The sloths, armadillos, and anteaters.
20:30The survivors have held their place by carving out specialisms, lowering their metabolisms to
20:42live on nutrient-poor plant diets, and by eating ants and termites.
20:49The origins of the next group are uncertain and hotly debated.
21:06Though their roots may have been laid down in the Americas, the Afrotheria were a group that went on to evolve in isolation,
21:14when Africa drifted separately from the other continents.
21:26It is one of the most bizarre collections of animals that don't appear to be closely related at all.
21:33They might have started out looking something like this, a tenrec, now confined only to Madagascar.
21:46It looks like a hedgehog, but is not related.
21:52It doesn't appear to have much in common with the Hyrax, but these are Afrotherian cousins.
22:04And the closest cousins of the Hyrax are perhaps the strangest links of all.
22:19the elephants and sea cows.
22:34All three have similar rounded hooves and unique teeth, most visible in the elephants.
22:48In convergent evolution, the sea cows, like manatee, are the only vegetarian marine mammals.
22:55These slow-moving, gentle giants have no relationship at all to whales or seals.
23:07The supersizing of giant mammals, like elephants, happened quickly, around 56 million years ago, perhaps because of climate change.
23:28The so-called Paleocene-Eocene thermal maximum, a sudden spike, raising the planet's temperature by around six degrees.
23:41It's thought massive volcanic activity might have been the trigger, raising carbon levels in the atmosphere, a greenhouse gas, trapping the sun's heat.
24:03The event rapidly changed animal and plant communities again, and seemed to have accelerated mammal evolution.
24:22Some of the most dramatic twists and turns in the family tree occurred, shaping mammals as diverse as bats and whales.
24:41These belong to the third major placental group, the Borioeutheria, the so-called True Beasts of the North, because they evolved on Laurasia.
25:01This group contains all other mammals in the most dramatic diversity, that were all shrew-like to begin with, like the Eulipataifla, sharp-toothed insectivores, including shrews.
25:27Hedgehogs.
25:28Hedgehogs.
25:29And moles.
25:34Then the Chiroptera, the bats, which make up 20% of all mammals, over 1,000 species.
25:52A few of the dinosaurs had escaped extinction.
26:05We know them today as birds, and they have mastered the skies.
26:18Bats are the only mammals to give them a run for their money.
26:25Coming out at night, bats mostly have the skies to themselves.
26:33They are highly specialist.
26:38Some are plant-eaters, and through eating fruit and nectar, vital to plants as pollinators and distributors of their seeds.
26:46But most are skilled hunters, snatching insects and other small prey on the wing.
27:02To hunt in the dark, they developed a unique tool.
27:07Echo location.
27:11They make high-pitched calls, often very loud.
27:17But too high-pitched for us to hear.
27:32Large sensitive ears can pick up the echo of their voice, bouncing off objects in their path.
27:38They can even detect obstacles no thicker than a human hair.
27:47The ultimate stealth weapon to guide them to their prey.
27:53Another group, known as glias, gave rise to the rabbits.
28:11To the rabbits.
28:18Hairs.
28:28And pica.
28:32Pure vegetarians have found an unusual way of digesting the most goodness from their food.
28:39By eating their own poop.
28:56They share a close kinship to rodents.
28:59The most successful group, making up 40% of all mammals with more than 2,000 species today.
29:09They appear right after the dinosaurs and massively diversified during the Eocene.
29:22Conquering almost every habitat and corner of land.
29:26Unlike the vegetarian rabbits, they are opportunist omnivores.
29:33Mostly plant eaters, but will have a bit of anything and everything.
29:39Rodents have paired incisors that never stop growing.
29:52These front teeth rub together, grinding a flat surface to make sure they are always sharp.
29:58Though rodents have mostly stayed small, there were some species that reached buffalo size.
30:17The biggest today are the sheep-sized capybara.
30:32One of the most diverse groups of mammals to share a common ancestor are the ferroungulata.
30:47Huge competition took off among members of this group.
30:51Furnishing food chains with both predators and prey.
30:58An uneasy relationship formed in the carnivore clan.
31:04From shared ancestry with pine martins, badgers and otters.
31:19The world's great carnivores competed with each other as they do today.
31:23The bears, dogs, hyenas, big cats, all trying to carve out their own niches.
31:51From pack-hunting wolves to the cheetah, the fastest mammal.
32:20And their diversity was driven by the emergence of plant eaters from the same family tree.
32:37The animals with odd numbers of toes, like horses.
32:43Horses.
32:51Tapir.
33:00And rhino.
33:01Horses were a hugely successful and diverse group.
33:08And rhinos were widespread and abundant.
33:19They broke records in becoming the biggest land mammals.
33:22The only species to come close to the size of the giant dinosaurs.
33:28There were also animals with cloven hooves.
33:44All of the buffalo.
33:49Hyped.
33:50Uno.
33:52My
34:15And from the same origins, incredibly diverse animals like pangolins, which, unlike the
34:27rest of the family, became specialist anteaters.
34:40And the final twist, some of the ancestors of the early hoofed mammals started to paddle
34:46in warm, shallow lagoons.
34:52These were to turn back the clock.
34:56Mammals most ancient ancestors, fish, lived in the oceans.
35:01And now some of the mammals, evolved on land, returned to the ocean to exploit them, becoming
35:09whales and dolphins.
35:20They maintain all of their mammalian features, warm-blooded, air-breathing, and still producing
35:26milk for their young, yet supremely adapted for life beneath the waves.
35:41In more convergent evolution, the toothed whales and dolphins developed an echolocation not dissimilar
35:48to the bats, but they produce their clicks and whistles in their blowhole, which passes
35:58out through the melon, the fatty organ on the forehead.
36:07This focuses the sound into a powerful beam that can be aimed at its target.
36:14The returning echoes are picked up by the jaw, which has an oil-filled channel connecting
36:19it to the ear.
36:38One other group of mammals sought to exploit the bounty of the seas, but they didn't evolve
36:45from the same ancestors as whales and dolphins.
36:49The seals, sea lions, and walrus evolved from carnivora.
37:02They are cousins to bears and otters.
37:13The southern elephant seals are the largest members of the carnivora clan.
37:21Known as pinnipeds, they form three distinct groups.
37:30The eared seals are the fur seals and sea lions that have powerful shoulders and swim with big
37:37front flippers, the so-called true seals that are clumsy sausage shapes on land, but speed through
37:54the water, powering themselves with their hind flippers.
38:07And the huge arctic walruses with their unmistakable tusks.
38:24Hugely successful marine hunters, they have conquered all waters, from the tropics to the poles.
38:34But unlike whales and dolphins, they are still tied to the land, hauling ashore to give birth.
38:46In just a few tens of millions of years, every niche filled by dinosaurs and other prehistoric
39:01reptiles had been seized and exploited by the newly emerging mammals.
39:12They had conquered land, sea and sky, some as small as a bee, some weighing as much as a dozen school buses.
39:27But there was one other branch of the mammalian tree that swung into action, right back when the last dinosaurs were rotting into the earth.
39:42With only scant remains, the tantalizingly few fossils of primates leave a lot of mystery about exactly where and when our own family came into being.
39:57But by the time the mammal takeover really got underway, we were firmly on the map.
40:16At the time, our ancient primate birthplace was Laurasia, the vast northern continent.
40:25And fossil remains have turned up in what is now North America, Europe and China.
40:31The family tree starts with little, big-eyed, nocturnal scampering tree climbers.
40:45Later fossils in Europe reveal the lemur-like Northarctus.
40:59As land masses moved, the early northern primates were able to colonize Africa.
41:13True lemurs are not a step on our evolutionary ladder, but rather a branch off the tree.
41:20Some time around 50 million years ago, they became a unique group.
41:26But give a window on the past, because they are the only primates to still have a wet nose and reflective eyes to help them see in the dark like other mammals.
41:38The rest of the primates gradually developed a dry nose and better eyesight, but with less ability to see in the dark as they became less nocturnal.
41:56Some time between 30 and 40 million years ago, there was another branch.
42:14Though we often think of the Amazon as monkey central, monkeys didn't evolve there.
42:24Monkeys crossed the Atlantic to South America.
42:26Whether they rafted, island hopped, or used temporary land bridges remains a mystery.
42:32But these so-called New World monkeys are not closely related to the Old World ones of Africa and Eurasia.
42:44A vast majority of the living and the problems were not isolated when they were happy.
42:46So why did you emerge from the marked as the oil?
42:47So the coast of the river will be freezing and they will be freezing?
42:48And there's no way to vemos on the island happening after the peace of the river.
42:49The you-thing and the sea-rise even after theou-things are associated with.
42:50The east coast of the river will be with the sea-rise here.
42:52The lake isoyu and has been made for a different mountainändert.
42:54This is the next island of the lake at the nivel.
42:55But the river will end up to the island!
42:57The river willå” Ð¿Ð¾ÐºÑƒÐ¿ate in the city of the river and the river will be buried at the river.
42:59The river will strike up the river again!
43:04The river will come to the river and air.
43:05Around 29 to 24 million years ago, there was another major branch, an important one for us.
43:26Apes went out on a limb, separating from the monkeys.
43:30Vegetation had been changed radically by a shifting climate and geography, as mountain ranges were thrust up.
43:45In places, forests were opening, and grass, a relative newcomer, was colonizing.
43:52Some primates started living on the ground to exploit this new resource.
44:02Other apes remained in the forest, becoming the great apes we know today, like gorillas and chimps.
44:13Other apes remained in the forest, becoming the great apes we know today, like gorillas and chimps.
44:26They are highly intelligent, tool-using, and social.
44:47But they remained strongly sexually dimorphic.
44:57The males are much bigger and heavier than the females, and with enlarged canine teeth.
45:02There can be a lot of aggression and violence in their societies.
45:15But by six million years ago, the earliest proto-humans were recognizable as something different.
45:36We were already walking upright, and males and females were more alike in size and appearance, and with reduced canines, showing a shift in our social grouping.
45:57On the grassy plains of Ethiopia, the first humans roamed.
46:07Many species of human evolved, and some dispersed out of Africa into Eurasia.
46:17But our great parents, the first homo sapiens, appeared around 300,000 years ago in Africa.
46:33Over the following tens of thousands of years, humans were building shelters, hunting with spears,
46:56and even using pigment to record and share ideas.
47:09Culture and language developed, far more complex than any that had gone before.
47:15And we developed an insatiable urge to travel, spreading around the globe.
47:30A huge change occurred around 12,000 years ago in the so-called Fertile Crescent, a lush stretch of land from Egypt to Turkey.
47:58People began to settle and farm, domesticating wild species, and shaping the landscape to suit their needs.
48:16Humans were innovating.
48:23It was the start of an endless progress of technologies that shaped our societies and the world around us.
48:30From the discovery of fire, and shaping of the first stone tools, we have gone on to great things.
48:49Complex language, rich cultural societies, developing the arts, and creating the most extraordinary technologies.
49:04But it's come at a cost.
49:11Many say that the Earth entered a new era, the Anthropocene, the age of humans.
49:23It's come at a cost.
49:25Sadly, the fossil record in the future for this period will be one of destruction, the demise of the natural world.
49:37Instead of fossils of plants and animals in the rocks, our age will be defined with layers of chemical and plastic pollution, even radiation from nuclear bombs.
49:49An era of over-exploitation of the planet's resources and climate-damaging dependence on fossil fuels.
50:03We are creating a new mass extinction.
50:06But unlike the others that have gone before, our climate change isn't caused by massive volcanic eruptions, but by us burning landscapes and burning fuel.
50:19One thing that sets the human mind apart is our thirst for knowledge, including a desire to explore our past.
50:32We know the pattern of extinction events and how even dominant species can vanish.
50:38Whether we, human beings, will make it through this extinction event is unknown.
50:45It's been largely caused by our technology.
50:50Now, that technology could be used to save us with the backing of political and societal will.
51:01We have another unique human trait, a sense of morality.
51:12We have massively changed the planet and have the power to change it again for the better.
51:20Our choices now will dictate the next chapter of the history of life on Earth.
51:29Welcome to Earth, Montana.
51:42Nevertheless, we will evaluate things.
51:48The new way is powerful for people to understand.
51:49We are double decades of——
51:50The new way is organized.
51:57We live now with their energy.
51:58You