A family of very sleepy sloths
unlike any you've seen before,
They've been sheltering in this cave since the baby was born two months ago,
But now the mother is hungry,
and that means a difficult day ahead,,,
because they're marooned in the middle of a desert,
and all that's left to eat
is at the top of a mountain a mile high,
This is the Ice Age,
Far to the north, temperatures are plummeting as ice sheets grow,
but in the south, drought rules the land,
Deserts are five times the size of those today,
Inhabited by the strangest creatures,
like supersized kangaroos,
killer koalas
and giant wombats,,,
,,,fighting for survival in the driest landscape seen for millions of years,
There are over 50 species of Ice Age sloth,
but this one could be the bravest,
It's a perilous climb,,,
but the mother has no choice,
Without food, she'll run out of milk and her baby won't survive,
Even in the middle of this desert,
moisture collects on the highest peaks, allowing plants to grow,
But the best food
is right at the top,
She needs to pick the very freshest leaves,
hundreds of them,
and that takes time,
Under the scorching sun, the clock is ticking
because rising thermals will soon bring deadly hunters,
If the family is caught in the open,
they'll be in trouble,
Finding food isn't the only thing that makes life difficult in the desert,
Since the start of the Ice Age, rainfall levels have halved,
A thorny devil,
It can make the most of a tiny pool of morning dew,,,
just by stepping in it,
Its scaly skin sucks up water and channels it to its mouth,
In these conditions, everyone needs a trick to survive,
A herd of female Diprotodon, rhino-sized relatives of wombats,,,
and the largest marsupial of all time,
Their trick is to migrate,
traveling for hundreds of miles between water holes,
And finding them is the job of the herd's leader,
She has great skill and an excellent memory,
Leading the herd on secret paths forged over many decades,
But now, she's old
and frail,
This year, the drought has proved too much,
For her, it's the end of the road,
The herd needs a new leader,
Two rivals,
Their bite has twice the power of a tiger's,
The winner,
the old leader's daughter,
And the herd quickly accept her,
Her first job is to find the next water hole,
Instinct and memories kick in,
Then, it looks like another herd enjoying a cooling drink,
A good sign,
But the water hole is dry,
It was just a mirage,
Others have made this mistake,
They're now a feast for wedge-tailed eagles,
The herd will never make it to another water hole,
Their new leader has failed them,
Or has she?
The riverbed looks dry,
but she digs anyway,
Water,
It's just enough,
Her persistence and ingenuity have saved them,
She's passed her first test,,,
and won the support of the herd,,,
,,,but this is just one of the many challenges ahead,
As deserts here grow to cover 90 percent of the continent,
the journey between water holes will only get longer and harder,
These barren landscapes also make life hard for hunters,
Marsupial lions,,,
related to koalas,
but these are predators,
And right now, they're suffering,
For the cubs, playing takes their minds off their empty stomachs,
Every day the adults head off to hunt,,,
,,,but it's weeks since they caught anything,
Their hunting grounds are turning from forest to scrubland,,,
now inhabited by formidable prey,
Giant short-faced kangaroos,
At seven feet tall, adults are out of the lions' league,
but the young look just right,
She's an ambush hunter,,,
but in these new scrublands, cover is hard to find,
These kangaroos are slow,
Top speed, around ten miles an hour,,,
but the marsupial lions,,,
are even slower,
Built for wrestling prey, not chasing them,
They're definitely more koala than lion,
She needs a new strategy,
Back at the lookout, everyone's hungry,
The hunt has failed,
and the cub's mother is missing,
Without her, he will starve,
This dung beetle is looking for a mate,
When he finds one,
his ball of dung will make the perfect gift,,,
but he's got a long way to go,
Forests are dying out,
It's been happening for thousands of years,
And everyone has to adapt,
A giant moa,
Six feet tall,
He is also looking for a mate,
These days, he has to cross deserts to find one,
His calls are full of information,
His age, fitness, size,,,
even the number of parasites,
A female can find out everything she wants to know,,,
just from the quality of his voice,
An answer,
If he looks a bit nervous,,,
there's a very good reason,
Female giant moas are ten feet tall,
The tallest birds that have ever lived,
But they like their males,,,
,,,small,
She weighs a quarter of a ton and could kill him with a single kick,,,
and he knows it,
To woo her, he needs to look as small as possible,
Small,,,
but not small enough,
Better,
That's quite enough of that,
A brief but successful encounter,
For the next two weeks, he won't leave her side,
Making sure she eats the right food,,,
seeing off any competing males,,,
,,,and, of course, looking small,
Deep in the forest,
the male has found the perfect spot to start their family,
A simple nest hidden away,
In moa family life, it's the father that cares for the young,
The egg is too delicate for the female to sit on,
Luckily, the male is three times lighter,
Being small also makes it easier to hide from predators
while he waits for the egg to hatch,
The smallest moa fathers raise the most chicks,
That's why the females seek them out,
And he's dedicated,
He'll not only look after his egg,
but when it hatches,
he'll take sole care of the chick for six long months,
And if it's a female,,,
,,,in less than three years, she'll be nearly twice as tall as he is,
Within these small pockets of forest, moas can breed for most of the year,
Others wait for the short seasonal rains,
When they arrive,
this strange type of Ice Age kangaroo makes the most of it,,,
by having twins,
Often one is bigger and bolder than the other,
Time to explore,
Most kangaroos are gentle grazers,
but these,,,
are carnivores,
Baby Megalania lizards,
hatching from eggs beneath the sand,
Where there's one,
there can be 20 more,
It's a great opportunity to practice hunting,
But these rock turrets even things up,
Game on,
But there's trouble on the horizon,
A fully-grown Megalania, 20 feet long,
Twice as big as a Komodo dragon,
They'll eat anything,
Even their own young,
These baby kangaroos are good climbers,,,
,,,but so is this Megalania,
Luckily, there's one more thing these kangaroos are good at,
Jumping,
The little brother is safe, and the family are reunited,
Maybe a valuable lesson has been learned,
This desert is a treacherous place to raise young,
Even the most dedicated parent can get it wrong,
The mother sloth has spent too long feeding,
She and her baby are now in danger,
In the midday sun,
rising thermals give flying hunters a free ride to the mountain tops,
Teratornis,
Deadly predators with a ten-foot wingspan,
Climbing down is much slower going,,,
and dangerous,
Teratorns are smart,
They know that if they throw her off balance,
the fall will do their dirty work,
The cave is tantalizingly close,
Teratorns don't give up easily,
But the tables have turned,
Sheltering here means this family has found a way
to survive in the Ice Age desert,
It's the perfect place to keep her baby safe,
But not everyone is so lucky,
The baby marsupial lion is alone and hungry,,,
but he hasn't been abandoned,
His mother is still out hunting,
She's found her new strategy,
but it's dangerous,
Short-faced kangaroos lick their wrists to cool themselves down,
But in this heat, it's not enough,
They need shade,,,
and that's an opportunity,
It's a 35-foot drop,
No mistakes,
Success,
But now she has to drag this meal,,,
,,,all the way home,
The wait is finally over,
Thanks to their ingenuity, the family is holding on,,,
but the harsh, dry climate is spreading to every corner of the planet,
and it's here to stay,,,
creating yet more challenges for life in the Ice Age,
As the Ice Age continues,
the climate forges a remarkable and abundant new habitat,
Grasslands,
Weird and wonderful creatures make the most of this huge source of food,
Grazers gather in vast herds,
Violent storms sweep the plains,,,
,,,and deadly predators fight for supremacy,
The Ice Age brought the coldest conditions for 60 million years,
But while much of the north was covered in ice,
to the south, it was a completely different story,
Not extreme cold, but dry,
Deserts,
The Ice Age fundamentally changed the water cycle on Earth,
In one part of the world, you've got huge amounts of ice,
but, at the same time, some places were super dry,
So how and why did that happen?
To really understand Ice Age deserts,
there's no better place to go than Australia,
Prior to the Ice Age, Australia would've looked very different,
It would've been much more lush,
It would've had a lot more water, waterways, forests,
All of these kind of lush, vegetated environments,
Today, Australia is one of the driest continents on Earth,
What caused this dramatic change?
Hidden beneath the sand in this vast desert
is an extraordinary fossil site,
Over 600 skeletons that tell the story
of what happened to Australia in the Ice Age,
When we find a bone,
quite often, there's only a tiny bit exposed on the surface,
We carefully dig around the bone so they can then be removed,
In this pit is an adult Diprotodon skeleton,
Diprotodon were adapted to migrating huge distances to find water,
There are hundreds of Diprotodon fossils here,
so you might expect it to be a place that was full of water,
but there's something strange about this site,
It seems the animals here all died the same way,
Anywhere a fossil is present, they seem to be flat out on the surface,
but more often than not,
there's one limb that's gone down beneath the surface,
The legs often stand vertically
with the rest of the body slumped to the side,
This strange position suggests they got trapped in deep mud,
This desert used to be a vast lake,
but instead of the water the animals expected,
they found something different,
Diprotodon are coming out onto the lake surface in search of water,
then they're breaking through the crust and they're getting stuck,
and that's where their journey has ended,
The sad story of so many Diprotodon dying here
suggests that during the Ice Age,
this part of Australia was drying out and turning to desert,
The whole landscape is just completely changed,
This was happening right across the planet,
and like everything in the Ice Age, it's thanks to the ice,
During the Ice Age, there was a huge amount of ice
in the northern hemisphere,
In fact, about 25 percent of the land was covered in ice,
and there's a finite amount of water on the planet,
When all that water is locked up in the northern hemisphere,
it means less for rainfall, for clouds, for rivers,
With so little water in the atmosphere,
some of the world's deserts became five times their previous size,
Animals which weren't able to adapt
to those changing conditions would've been struggling for water,
It's strange to think of animals dying of thirst during the Ice Age,
but as the climate changed,
that would've put pressure on all of these animals
and drove them to the point of extinction,
This happened in Africa, Asia, South America and Australia,
Once lush areas dried out, some became deserts,
A change that was ultimately too great for many to survive,