RICHARD SMITH: Over four billion years in the making.
An island adrift in southern seas.
It's Australia, the giant Down Under.
A young nation, with all the gifts of the modern age.
But move beyond the cities and an ancient land awaits... One nearly as old as the Earth itself.
Australia is a puzzle put together in prehistoric times.
And the clues that unlock the mystery can be found scattered across Australia's sunburnt face.
I'm Richard Smith, and this is an amazing country.
I'll show you that every rock has a history, every creature a tale of survival against the odds.
Join me on an epic journey across a mighty continent, and far back in time.
Of all continents on Earth, none preserve the great saga of our planet and the evolution of life quite like this one.
Nowhere else can you so simply jump in a car and travel back to the dawn of time.
In this episode, with dinosaurs dead and gone, Australia sets sail for the modern world.
Isolated and alone, life leaps into some unusual territory.
We're uncovering lost worlds and subterranean death traps.
Blimey this is tight!
An exotic band of castaways ruled this far away land... until we turned up.
From Australia's ancient stones comes the story of our world.
"Australia's First Four Billion Years: Strange Creatures."
Right now, on NOVA.
Major funding for NOVA is provided by the following: SMITH: So far, our travels down Australia's road of time have taken us from the very formation of the earth, through the forging of the continent, to the origin of life and the conquest of the land.
GPS VOICE: Your destination is the present day.
SMITH: But it is only now, as we race towards our modern world, that the familiar face of Australia is finally revealed.
This is the story of how an island continent became isolated from the rest of the world.
And how the life aboard this wandering ark adapted to a changing landscape.
But it's a rocky road we travel.
(explosion) When the age of the dinosaurs came to a dead stop 65 million years ago, a great darkness settled over the planet and the whole course of evolution shifted.
When the skies began to clear in the first grim days of the Paleogene, most of the great Cretaceous forests were gone.
But life on earth is tenacious.
Ferns were quick to take advantage of the new world, colonizing what was left of the damaged forests of Australia, Antarctica and New Zealand.
And following closely behind the ferns, a remarkable Australian tree made a dramatic comeback in the post-apocalyptic world.
This is its microscopic seed, found fossilized amongst the fern spores, just above the level of the asteroid debris that marks the last days of the dinosaurs.
Like a B-grade monster, this is a tree that is hard to kill.
(loud rain drops) It's the huon pine.
Every branch that falls can re-sprout from the ground.
This entire tangled glade is a clone from a single original ancient tree.
Now the huon pine is more than just one of Australia's great Gondwanan survivors.
this particular tree is thought to be Australia's oldest living organism.
It's been growing on this same spot-- the cold, wet, windy slopes of Mount Reid in Tasmania-- for over 10,000 years.
(water dripping) But while life was on the rebound, the supercontinent Gondwana was in its death throes.
And the consequences for Australia would be dramatic.
(explosions) India and New Zealand had already slipped away.
Now Antarctica and Australia were being torn apart.
First, a great rift valley opened up and widened.
Then Australia and Antarctica started to unzip from the west.
A trickle became a flood as a new southern ocean surged into the gap between the separating lands.
Only Tasmania stood firm, holding the two continents together.
Today, Tasmania wears its war wounds with pride.
For over a hundred million years, intruding molten rock had been forcing its way upwards, looking for a weak spot.
This is the volcanic dolerite rock that now dominates Tasmania.
There's more of this rock here than anywhere else on Earth.
Towering dolerite sea cliffs guard the coast.
Dolerite punches through the highlands.
And the rock glowers over the capital of Hobart itself.
(sheep bleating) All indelible evidence of the dying days of Gondwana.
This was a torrid time across the planet.
Although much of the Australian landmass still lay within the Antarctic Circle, the climate was warm rather than polar thanks to a sudden surge of greenhouse gases that peaked around 55 million years ago.
In this steamy world, the conifers that had dominated the forests of the dinosaurs were now being replaced: by broad-leafed, flowering rainforest trees.
Some live on, here, in Tasmania's forests.
These leaves belong to a characteristic Gondwanan tree: the southern beech, Nothofagus.
You can still find Nothofagus on the Australian mainland, in South America, and even Antarctica... as fossils.
They're a reminder of the days when Tasmania was holding the last of Gondwanan brotherhood together.
At the time, you could have walked all the way from Australia, via Tasmania and Antarctica to South America, without ever leaving the green embrace of the Great Gondwanan Forest.
And it was through this green trans-Antarctic highway that marsupial mammals scurried out of the forests of South America and onto Australian soil.
Marsupials-- mammals with a pouch to carry their young-- now dominate Australia.
But marsupials were neither the first nor the only mammals in the country.
They found themselves mingling with the monotremes-- curious furry enigmas like the platypus that still laid eggs, a legacy from their distant reptilian ancestors.
Only two types of monotreme live on our planet today, and they're both a little peculiar.
Now this little guy, of course, is a truly famous Australian.
It's the echidna, or tachyglossus.
It is one of the true survivors of the early age of mammals.
And we know that because it lays eggs like the platypus.
He's tunneling to China I think.
But there's another group of survivors from those Mesozoic times with even closer reptilian affinities than the echidna.
And they still inhabit the forests of their forebears.
(various animal noises) One type of feathered dinosaur did survive the great extinction.
Today, we call them birds.
Come eye to eye with the flightless cassowary and the close family connection is hard to miss.
(screeching) (bird calls) While cassowaries owe their existence to the dinosaurs, the rainforests of tropical Queensland owe their existence to the birds.
It's a chain of connection that links down through time all the way to the Hewett family, modern human residents of the ancient rainforest at Cooper Creek.
The cassowary has evolved to become a modern distributor of forest fruits and seeds, a job likely first done by herbivorous dinosaurs.
(roars) This is the cassowary plum.
The cassowary is the only animal large enough to be able to swallow this fruit whole, and in doing so increase its germination rate from 7% to an ultimate 92%.
(water dripping) SMITH: In a complex relationship for mutual advantage, at least 37 species of rainforest tree rely on the cassowary for dispersal.
It's a big job, but someone's got to do it.
...the place that gets well over ten meters.
SMITH: Neil Hewett makes a living here too, sharing the rich botanical heritage of his 130-million-year-old back garden with visitors like me.
HEWETT: Here in the Cooper Valley is the world's richest diversity of primitive flowering plant families found anywhere on the planet.
SMITH: These rainforests are extremely old-- far older than the Amazon, and probably the oldest continuously surviving jungle in the world.
Today, they cover less than 1% of the surface of Australia.
It seems hard to believe, that for so many millions of years, most of this now arid continent was festooned with forests of almost unimaginable richness.
All that changed the moment that Tasmania finally let go of Antarctica.
And with the apron strings torn asunder, sometime between 30 & 40 million years ago, Australia sailed free from the rest of the world.
When not only Australia but the Patagonian tip of South America also let go of Antarctica, cold ocean currents were able to sweep freely around the southern continent for the very first time.
And Antarctica's fate was sealed.
SMITH: Encircled by icy currents, Antarctica, and all who sailed on her, began to freeze solid.
Australia, loaded to the gunnels with Gondwanan refugees, set course for the tropics-- a raft of life adrift on a sea of change.
And as it drifted, it dried.
It was more than a passage into warmer climates.
The freezing of Antarctica had taken much of the planets available fresh water with it.
This was the trigger for one of the planet's great biological experiments.
Isolated and alone now, Australia's plants and animals began taking on their own unique identity.
A remarkable rocky record of this defining moment has been found at Riversleigh in northwest Queensland.
When the fossil window re-opens in the rugged limestone hills here, it opens with a bang.
For prehistoric animal hunters like Mike Archer, Riversleigh is one of the richest caches on the continent.
MIKE ARCHER: We know nothing about Australia's mammals right through the period when Australia separated from Antarctica at 35 million years ago.
Until suddenly, the window is thrown open and there are thousands of fascinating things to look at.
They document the last 26 million years of Australian history in exquisite detail.
SMITH: With every fossil-rich boulder recovered, and bone, tooth and jaw released from acid bath, the ancient animals of Riversleigh are telling their own back story of Neogene Australia.
It was in the Neogene that Australia began to show its true colors.
ARCHER: The beginning of Riversleigh's story was of a rich forest...
Cool, temperate, permanently wet, no seasons.
So we started thinking about this as a kind of green cradle.
Here were the first brush-tailed possums.
Here were the first ring-tailed possums.
Here were the first koalas.
All the things people think about today as typically Australian animals had their roots in these ancient rainforests.
SMITH: By the time Riversleigh's window into time was closing around 15 million years ago, the rainforests had begun their long retreat.
As the continent edged closer to the equator, the blooms of many new types of flowering plants started bursting out across the land.
Amongst them, a previously low-profile, low-spreading plant took root.
(insect buzzing) For the first time, extensive grasslands spread out across the continent, ready for the nibbling.
Think Australia, and one grass- grazing animal above all others leaps to mind.
FLANNERY: Kangaroos are the archetypical successful mammal in Australia.
They've taken over every ecological niche, from the tropical rainforests in the treetops there through to the harshest deserts in Australia.
And they do something that no other large animal does, which is to hop.
SMITH; Perhaps the most energy-efficient means of forward motion developed by a mammal, hopping allows kangaroos to move vast distances over a tough country.
The quintessential Australian they may be, but how did such a biological oddity come about?
If you can take the bag for me?
SMITH: It's a puzzle that mammalogist Tim Flannery has sought to solve since his early 20s.
FLANNERY: I crawled around on my hands and knees for days on the edge of a salt lake and I finally picked up this thing that was the size of a match head really.
It was just this tiny bone.
and I knew immediately...
I put it on my tongue, washed the salt off it so I could see it properly and knew that it was the ankle bone of an ancient, ancient kangaroo, far more primitive than anything that had been seen before.
SMITH: Tim had found the missing link between the kangaroos tree-loving, possum-like ancestors, and the ground-dwelling, grass-nibbling hoppers on the country's coat of arms.
FLANNERY: If you look under the microscope here, you'll be able to see that little stepped facet there.
See how it's got like a double step on it.
Oh, absolutely, it's clear as day.
SMITH: However small, the shape of this ankle bone is the key to the kangaroo story.
With this stepped facet locking the bones closely together, ankle twisting was a thing of the past.
FLANNERY: Kangaroos evolved from possums, possums need to have a very flexible foot.
If kangaroos had an ankle like that, they would dislocate their ankle every time they hopped.
That stepped structure is what they evolved.
(thunderclap) SMITH: All this early ankle experimentation took place in the rainforests of Australia's green cradle.
And it's back in the damp jungles of far North Queensland that you find the closest surviving relative of the first kangaroo.
And here she is... the musky rat kangaroo.
The most primitive living member of the kangaroo clan, and a living fossil.
The first thing you'll notice about this busy little girl is the way she moves.
No matter how long I sit here watching her eat food in the forest, she'll never hop.
Hopping, for kangaroos, came later.
Down from the trees, and now with improved ankle bone technology, the first kangaroos were set to make that giant evolutionary leap.
And in many ways, the story of their evolution charts the course of the drying out of the continent itself.
Not only new animals emerged out of this green cradle, the plants were changing too.
The old Gondwanan forests shrank steadily back to the country's damp coastal corners, and in their place rose another true Australian original... the gum tree.
Now this is a tree definitely worth hugging.
Meet Centurion, the tallest eucalypt in Australia, and the tallest flowering plant in the world.
This towering Tasmanian mountain ash-- a species of eucalyptus-- has recently been laser measured at 327 feet high.
Only the giant Californian redwood, a conifer, grows taller.
The eucalypts have come to dominate the country.
Gum trees have proven themselves in the toughest environments Australia can throw at them.
They laugh off droughts and stand tall in the floods that follow.
They soldier on deep in snowfall, and respond to the perishing heat of a bushfire with a burst of new green growth.
These are the trees that love a sunburnt country.
And just as well.
About five million years ago, desert began to finally claim central Australia.
The last vestiges of a jungle flora, now surrounded by a sea of sand and spinifex grass, found refuge deep in natural soaks and damp gorges.
Arid Australia had arrived, and so had the Quaternary.
The slow drying of the continent had pushed kangaroos out of the trees and onto two legs.
But as Australia drifted north, it blocked the flow of moisture to the west as well, pushing an upright ape to stand tall on the plains of Africa.
But even more change was on its way.
The ice ages.
While Australia escaped the heavy ice sheets that remodeled the landscapes of the northern hemisphere, these cycles of freezing weather and glaciation sucked even more moisture from the sky.
Sea levels dropped dramatically, exposing dry land from New Guinea to Tasmania.
Plants grew even tougher and less nutritious.
It was a climate change that pushed animals in a radical direction, best seen with a swift descent into South Australia's Naracoorte Caves.
Paleontologist Gavin Prideaux has offered to guide me to the big game of ice age Australia.
The ground under Naracoorte is riddled with caverns into which animals have stumbled and fallen to their deaths.
As holes to the world above opened and closed over time, snapshots of a changing land were preserved in the subterranean darkness.
In 1969, a team of scientific cavers pushed on into the bowels of the earth here.
Further than you might think sensible.
This is the famous squeeze.
SMITH: So we're going through there?
PRIDEAUX: Yes, we are going through there.
You're kidding me.
Helmet on the side as you come through the tight bit then just use your toes to push yourself along.
SMITH: Some people do this for fun.
Blimey, this is tight.
SMITH: And it probably is if you like being the human meat in a mountain sandwich.
PRIDEAUX: You through, Richard?
SMITH: Most of the mammals that entered these caves never made it out alive.
PRIDEAUX: Here we are, Richard.
SMITH: The pit of doom.
PRIDEAUX: It certainly was.
SMITH: When the first cavers emerged into the Victoria fossil chamber, they came face to face with a megafauna graveyard.
Megafauna means giant animals, basically.
Big animals from the last million years or so.
Animals like Diprotodon, about the size of a rhinoceros, probably weighed around two-and-a-half tons.
SMITH: Diprotodon, the largest marsupial that has ever lived, grazed alongside the largest kangaroos of all time.
Procoptodon goliath grew over two meters tall.
It all relates to the fact that larger animals have a much lower metabolic rate, and that means they can survive on much rougher, less nutritious vegetation, becoming more and more widespread across Australia as the country dried out.
Of course the carnivores, the meat eaters, get bigger because the herbivores get bigger.
SMITH: This is the skull of Thylacoleo, Australia's marsupial super carnivore.
It had stealth, speed and a bite force without mammalian equal.
Thylacoleo was the top mammalian predator in ice age Australia, but not for long.
A placental mammal made landfall somewhere on the northern coastline.
It didn'’t fly in like the bats or swim like the rats.
This mammal must have come by boat.
The first human footsteps on Australian soil were made somewhere between here in the Kimberley and Arnhem Land in the Northern Territory.
The people came out of the setting sun from Indonesia in the northwest, and they came a staggeringly long time ago.
Modern science is now able to put dates on the arrival of the first people.
Geochronologist Bert Roberts uses sand grains and laser light to peer back to the start of the human story.
BERT ROBERTS: Using the very best techniques we can at the present stage, we now think people got to Australia maybe 50,000 or 60,000 years ago, and the very earliest occupations took place in the north of the country, maybe through Kakadu maybe through to Kimberley.
SMITH: Wherever those first people landed, they found themselves on a lonely, alien coastline.
With the oceans rising behind them and a dangerous welcoming committee, they pushed on.
FLANNERY: Once you push your way through the mangroves, you would have found a world unlike anything that you'd seen.
There would have been gigantic tortoises with horns like a cow.
PRIDEAUX: There was a giant flightless goose-like bird called Genyornis.
ROBERTS: Huge wombats, huge kangaroos, giant echidnas, even giant koalas.
60 species of short-faced kangaroos.
And giant goannas, about five times the size of a Komodo dragon.
(roaring) SMITH: It was a land of plenty.
From the beach heads of the tropical north, it seems the first people spread rapidly south.
Following the coast and tracking inland along the watercourses, they penetrated deep into the heart of the continent.
Within only a few thousand years, it seems, people were camped by the shores of Lake Mungo in far western New South Wales.
In 1969, fragments of a cremated skeleton were found weathering out of the bone-dry lake shore.
A second discovery soon followed.
With dates firming at around 40,000 years, these are the oldest human remains yet found on the continent and some of the oldest ritual burials in the world.
This is bone five.
SMITH: The crumbling clay of the prehistoric lake edge is still releasing secrets.
Animal dinners cooked on fires amongst the dunes.
Fragments of stone tools.
Relics that speak to archaeologist Nicola Stern of distant times, changed climates and a forgotten landscape.
NICOLA STERN: My interest is primarily in the rubbish left behind from people's everyday life.
It's a record that spans the entire history of human settlement on the continent, about which we know very little.
SMITH: Clues left behind in the lakeside cooking fires paint a picture of lakes brimming with water and fish, fringed with trees and wildlife.
A different Mungo from today.
Mungo is a magic and moving place.
You can walk in a landscape where people have been leaving footprints for over 50,000 years.
There's few places on the planet with such a continual record of human occupation.
Half close your eyes and you can almost hear the sound of people camped on the shoreline and enjoying a sunset much like this.
There are other ghosts in this landscape.
Even before the first human burials here, the giant animals of the megafauna had disappeared from the continent.
The timing alone suggests human involvement, but this remains a scientific cold case hotly debated.
Some suspect that the shifting ice age climate did them in, but the records stored in the bone beds of Naracoorte suggest otherwise.
PRIDEAUX: The populations of different species of mammal waxed and waned, if you like, in response to those glacial and interglacial cycles.
But nothing became extinct until about the time humans arrived.
SMITH: Whatever it was that killed these giant animals, a final desiccating wave of global glaciation was soon making life tough for the humans that survived them.
At its peak around 20,000 years ago, the bountiful land faltered.
Forced back to the security of the lakes, Mungo people marked their passage on the edge of a drying claypan.
But these first Australians left behind more than footprints.
Rock shelters on the Kimberley coast hold a collection of cultural evolution extending back, it's suspected, as far as the last ice age.
With the arrival of the first people, the story of Australia was written not only in the rocks, but on them as well-- rocks polished smooth by the rub of countless human bodies and artwork to rival any modern gallery.
It's the art gallery that never closed, still cared for by the artists' living descendants, like Wunambal man Greg Goonack.
Welcome to Wunambal country.
Pleased to meet you.
I'm so glad to be here.
It's just so impressive... SMITH: This is the collection of artwork that archaeologist June Ross and her team are keen to fully document and date.
JUNE ROSS: It is the story of Australia.
It's the story of the people who were here first.
People have lived here very successfully for thousands and thousands of years, and we are very interested in knowing how they managed to do that.
SMITH: Recorded here are clues to how people adapted to the evolving climate.
At least three conspicuously different styles are on display in the caverns.
The oldest are slender, elongated figures.
ROSS: They appear to be floating, almost standing on their toes like ballet dancers.
But the thing that fascinates me is all the different hairstyles and headdresses.
SMITH: This flamboyant style is then replaced by more business-like figures.
JUNE ROSS: So we think something is happening to the culture at this particular time.
We see a lot more weapons: the barbed spears, the hooked sticks.
SMITH: Whether or not dating will show this cultural shift was a response to a changing world, an evolving tropical climate certainly influenced the art of the last few thousand years.
(thunderclap) RANGER JOHN: Gorlingi!
We come with respect!
SMITH: Wanjina figures, like these images of the creator spirit Gorlingi, are strong cultural links to the modern monsoon, each wet bringing new life to the land.
ROSS: When I arrived at this site for the first time, it took my breath away.
And I think it has the potential to answer lots of highly significant questions, not just for Australians, but for the entire world.
(birds squawking) SMITH: Across the country, Aboriginal Australians were witness to extraordinary change.
They saw people walk to Tasmania, the last volcanic eruptions on Australian soil, and then the coming of the Europeans.
When navigator James Cook climbed to the summit of Lizard Island in 1770 after running aground on Endeavour Reef, he was horrified to find that his ship and crew were trapped inside a coral labyrinth, the extent of which exceeded his worst nightmares.
A maze of over 3,000 reefs and islands, extending for over 1,200 miles along the coast.
Australia's Great Barrier Reef is probably one of the greatest reef systems the planet has ever seen.
But Cook climbed up here for salvation, not scenery.
He was looking for a way out.
Surprisingly, if Cook had come only about 10,000 years earlier, he wouldn't have seen the reef at all.
His view from the coast to the horizon would have been of dry land because the Barrier Reef hadn't arrived yet.
At the height of the last ice age, sea levels plunged over 300 feet.
The older reefs were left high and dry.
Aborigines would have walked where sharks now swim, hunting kangaroos on hillsides that fish now graze.
As the ice age waned and the world thawed, the seas rose yet again.
Coral larvae drifted in to reclaim the seafloor.
Today's Great Barrier Reef, so big you can see it from space, is a surprisingly new arrival on the Australian stage.
And so, for the most part, are we.
In many ways, you can think of James Cook's climb here to the summit of Lizard Island as a kind of turning point, the place from where our modern, still-unfolding chapter of Australia's long story began, because it's from here that he spied an escape route back to England, and the modern world soon followed.
(ferry horn blowing) SMITH: It was like a collision of continents.
A sudden end to a long isolation.
In the blink of a geological eye, humans have altered the continent forever.
We've cleared and cultivated the land, losing prehistoric forests and ancient soils in the process.
The rest of the world has been brought in with us in the form of animals and plants, pests and diseases.
And much of what did live here has gone.
Well, in here, Richard, really is the cabinet of catastrophe.
Look at them all.
This cabinet is full of mammal species that no longer exist.
What we've got here is a desert rat kangaroo, last seen in 1931 in central Australia.
SMITH: Beautiful, the pelt... Look at the beautiful black subterminal bands.
And these are short-faced potoroos.
Last time these were seen: 1875.
This is a pig-footed bandicoot, last seen about 1906 in central Australia.
SMITH: And this is the final filmed record of the now extinct thylacine, the largest marsupial predator to make it into modern times.
FLANNERY: Now, the reason this was persecuted, this animal, was it supposedly killed sheep.
We now know that 80% or so of the sheep that did die were stolen by convicts; they weren't killed by this animal.
SMITH: What the film doesn't show is the moment when, in righteous indignation, the thylacine opened its remarkable marsupial jaws and bit the photographer firmly on his placental rear end.
Many of Australia's marsupials remain at risk.
FLANNERY: This extinction event is coupled with the one that happened 50,000 years ago, the giant megafauna.
It's on the sort of scale that we see in the great prehistoric extinctions.
It's the devastation of a continent.
SMITH: As clear as the cosmic dust marking the last days of the dinosaurs, our indelible radioactive signature is now being recorded in the rocks: the mark of the Age of Man.
(explosions) SMITH: Around the world, we have become a powerful force of nature, the equal at least of any life form that has come before.
You shouldn't underestimate the power of life to shape the planet.
After all, it was industrious prehistoric bacteria in the shape of stromatolites that created Australia's vast iron ore deposits.
And it's us, life in the form of humans, that can shift whole mountains of the stuff to the other side of the world.
Each year now, humans shift more rock and soil than the flow of rivers and glaciers carries to the sea.
And civilization is on track to burn as much energy each year as is released as heat from within the Earth.
In doing all this, we alter the chemistry of our thin, precious atmosphere and finite oceans.
And the geological extinction record shows we do so at our peril.
We may now hold dominion over the Earth, but the planet always wins in the end.
Almost nothing we see in the landscape of modern Australia will survive the test of geological time.
Eventually, all this will go.
Probably the bedrock itself.
Today's legacies will linger in the stories passed down in the rocks that are endlessly recycled and in the genes of living organisms that keep flowing down the road of time.
This ribbon of life runs unbroken through the history of the Australian continent.
The first lifeforms skirted the shoreline here.
Then they climbed ashore.
And now, four-and-a-half-billion years down the road, we have climbed aboard as well.
We may not know what lies ahead for us, but thanks to some very accurate GPS measurements, we do know where the continent is going.
Each year now, Australia and everything on it is moving about the length of my finger in this direction, towards the northern hemisphere.
Sometime in the future, Australia should cross the equator as it last did half a billion years ago.
(birds chirping) It will once again be part of another great supercontinent, a new world somewhere in the north Pacific.
Our challenge in this, our geological instant, is to steer a path that does not cut our own future short, and with it that of the many plants and animals along for the ride.
That is what is so remarkable about the age we live in.
For the first time in history, there is a species on this remarkable, walkabout continent that has that choice to make.
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