BBC The Natural World Complete Series

South America is a continent of extremes.

It has the world's longest mountain range... the Andes.

In Amazonia, it has the mightiest river

and the greatest expanse of rainforest on the planet.

And the driest desert on earth

the Atacama, lies beside one of the world's richest seas.

South America also contains incredible variety.

Almost no other continent can boast such a wealth of wildlife

living in such a range of different landscapes.

Almost everywhere you go

there's an extraordinary diversity of life.

But how did all these unique worlds come about?

To understand the natural history of South America

we must go back in time back to the age of the dinosaurs.

South America was then part of Gondwana

a massive continent

that also included what are now Africa Australia, India and Antarctica.

This was a world dominated by reptiles.

Descendants of those ancient creatures still live in South America today.

And the forests of southern Chile still have plants

that the dinosaurs would have recognised

tree ferns and the bizarre monkey puzzle tree.

Then, a new group of animals appeared animals like this.

The early mammals were small

and many were marsupials like this shrew opossum.

It lives in the cold damp forests of southern Chile

where it hunts for insects and earthworms.

The shrew opossum shares these ancient forests

with this other small marsupial.

Local people call it the 'monito del monte'

or 'monkey of the mountains'.

It's so tiny you could hold it in the palm of your hand.

It too eats insects but also has a taste for fruit.

When we think of mammals with a pouch

it's perhaps Australia with its kangaroos that comes to mind.

But South America also has over eighty species of marsupial

a legacy of the time

when the two continents were joined together.

Around a hundred million years ago

the giant continent of Gondwana slowly split apart.

South America became an enormous island

cut off from the rest of the world.

The next chapter in South America's history was violent and prolonged.

It changed the face of the continent for ever.

Starting some eighty million years ago

the island was convulsed by a series of massive volcanic eruptions

that continue today.

Forced up by movements deep in the earth's crust

a huge chain of mountains arose

spanning the length of the continent The Andes.

Running over five thousand miles

this is the longest mountain chain on earth.

At its northern end tropical cloudforest covers the slopes

yet its peaks are so high

that even on the equator they carry permanent snow and ice.

In the central Andes

there's a high dry desert the altiplano.

As you travel further south

the mountains are lower

but they're that much closer to the Antarctic.

In the far south

the Patagonian ice sheets are the largest

expanse of ice outside the polar regions.

They cover more than seven thousand square miles

and their glaciers flow all the way to the sea.

But even here

in the shadow of the ice animals survive.

In the shadow of the Patagonian icecap

animals must survive ferocious winds and winters of heavy snow.

Only the hardiest animals can live here

like guanacos South American relatives of the camel

and foxes.

Even for them

surviving the winter is a challenge

Patagonia may be severe

but it's not the most extreme part of the Andes.

That's back in the heart of the range

an oxygen-starved plateau more than four thousand metres high.

Here, in the Altiplano

meltwater from the surrounding peaks evaporates in huge salt lakes.

Frozen by night and baked by day

these caustic saltflats must be

one of the most inhospitable places on earth.

This is Salar Uyuni in the Bolivian Andes.

Covering four and a half thousand square miles

it's the largest expanse of salt on the planet.

Incredibly, islands in this sea of salt actually support life.

Viscachas.

These rabbit-sized rodents have to contend with thin air, bitter cold,

and an almost total lack of water.

They get just enough moisture to survive from their food.

Thick fur keeps them warm

and extra red blood cells help to absorb sufficient oxygen.

The thin air's a problem for this hummingbird too.

To conserve energy when it's feeding it has to perch, rather than hover.

The high altiplano may seem hostile

but some animals actually choose to come here.

Flamingos come here to breed

because these caustic waters are full of their favourite food.

They display to each other with a massed courtship dance.

The rise of the Andes created

whole new environments within the mountains

but it also had more far-reaching effects.

This great barrier changed the climate of South America.

It also re-drew the map of the entire continent

radically altering the course of its major rivers.

The Iguazu Falls are one of the wonders of the world.

Four times as wide as Niagara

they carry sixty thousand tons of water a second.

Part of Amazonia was once a huge swamp

connected to the Pacific and the Caribbean.

The rise of the Andes broke those links

forcing the major rivers to flow east.

One massive river now drains forty percent of South America... the Amazon.

This is the mightiest river on earth.

Running over four thousand miles from the Andes to the ocean

it carries a fifth of all the river water on the planet.

A thousand miles before it reaches the sea

its main channel is already ten miles wide.

Every year the mighty Amazon bursts its banks

flooding an area of forest the size of England.

At the height of the flood

the trees can stand in water ten metres deep.

The floodwaters bring with them the animals of the river

like boto dolphins.

Their origins are a mystery.

Could they be a relic of Amazonia's ancient links with the oceans?

These river dolphins are almost blind

no handicap in water that's often very muddy

because they navigate by echolocation.

Unlike marine dolphins they have a flexible neck

so by sweeping their head

from side to side they can scan their path ahead.

Their sonar is so precise that they can weave their way

through a maze of submerged branches in search of fish.

Whisker-like bristles on their lips help them zero in on their target.

The botos' origins may be mysterious

but some of the Amazon's fish certainly have a marine ancestry

like stingrays.

Their nearest living relatives are in the Caribbean.

The Amazon has over three thousand kinds of fish.

This is the pirarucu the world's largest fresh water fish.

And these are the most notorious... piranhas.

The variety of life in these waters is extraordinary...

and with so many fish there are bound to be fish hunters.

In this water world

Caiman are the top of the food chain...

the aquatic equivalent of the jaguar.

Red-bellied piranhas are predators themselves

but to a caiman they're just another mouthful.

The Amazon river and its tributaries

drain the largest expanse of tropical rainforest on earth.

Stretching almost unbroken from the Andes to the Atlantic

the Amazon jungle has a greater variety of life

than any other forest on the planet.

In just over two square miles of forest

scientists have counted three thousand varieties of plants

five hundred and thirty kinds of birds

and eleven different species of monkeys.

There are countless reptiles amphibians and insects.

Six hundred and fifty species of beetle

and eighty kinds of ant have been found on a single tree.

Scientists disagree about the reasons for this diversity

but in almost every group of animals

the number of different species is extraordinary.

Because there are so many species

most of them have to specialise.

Pygmy marmosets are the world's smallest monkey.

They live on the sap of just a few kinds of tree

gouging the bark with special teeth to release its flow.

They're just one of over thirty species of marmoset

and tamarin in the Amazon basin

a group of monkeys unique to the lowland rainforests of South America.

Like these tassel-eared marmosets most live in family groups.

A breeding female lives with one or more adult males

and several youngsters.

Females typically give birth to twins

and unusually among monkeys

it's the father who's left holding the babies.

Tassel-eared marmosets are opportunists.

As well as gum, they eat insects fruit, birds' eggs

small snakes and lizards...

almost anything they can get their hands on.

The youngsters must develop fast

if they're to survive in the dangerous

and competitive world of the rainforest.

Amazonia lies on the eastern side of the Andes

and here torrential tropical rains water the prolific jungle.

But the mountains block the moisture-bearing winds

so some of the western side receives almost no rain.

Here lies the world's driest desert... the Atacama.

The Atacama can go for years with literally no rain at all.

It's hard to imagine how anything could survive here.

And yet it does.

Guanacos.

These South American camels can tolerate extremes of heat and cold.

A desert might seem a better place for a camel

than the snows of Patagonia

but the Atacama is a challenge even for them.

Daytime temperatures can rise to forty degrees.