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The southwest states
of North America...

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a region of extremes...

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from the Colorado river
and desert canyons

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to artificial landscapes

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that teem with life,

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including one of
the world's most vibrant cities.

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This is Las Vegas

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a man-made oasis deep
in the Nevada desert.

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Only a century ago, this wonderland
was sand and scrub.

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Today it's one of the continent's
fastest-growing cities.

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All this depends on water

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pumped from the Colorado river
50 miles away.

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Without this imported water,
there would be no Vegas.

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But during the last Ice Age,

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the Las Vegas Valley had
a plentiful supply of water,

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and it was a magnet
for all kinds of wildlife.

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Just 13,000 years ago -

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not long in the vast
time-scale of a continent

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this valley overflowed
with lakes and ponds,

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fringed with the reed
beds and swamps...

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All kinds of creatures would have been
drawn to this natural refuge.

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One group of new arrivals in this land
of opportunity were people.

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As the Ice Age ended and new pathways
opened up across the continent,

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these hunters caught their first
glimpse of the Canyon lands.

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Imagine if we could travel back in time

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to see this wild new world

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and the strange and terrifying animals
that lived here 13,000 years ago.

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Using evidence left behind
by these creatures,

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we will recreate life
in the Ice Age Canyon lands.

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It's taken millions of years to carve

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the red rock sculptures
of the Canyon lands.

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Today they spread across several states

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including Colorado, Arizona,
Utah and Nevada.

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These isolated, high plateaux

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are still home to some animals that
were here at the end of the last Ice Age.

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Today, the mountain lion
is the largest predator

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that still patrols the canyons,

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living much as it did 13,000 years ago.

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It's a tough existence.

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Food is hard to come by, water too,

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and the desert climate swings

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from below zero overnight

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to nearly 40 degrees
centigrade by day.

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At least there's no shortage
of shade.

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A labyrinth of caves can offer shelter
from the heat and cold

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and from the dangers of the night.

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There was a time

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when even mountain lions
couldn't sleep in safety.

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These caves are haunted
by the ghost of another carnivore

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that dwarfed the mountain lion,

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probably the best known of
all Ice Age hunters.

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It killed with fangs like these,
20 centimetres long -

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the sabre-toothed cat.

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But how exactly were
these chilling weapons used?

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With its 300-kilo frame and short legs,

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the sabre-tooth was not that fast.

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It probably ambushed prey,

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using its huge weight to pin it down

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before delivering
a slashing bite to the neck.

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Shock and loss of blood
would quickly kill its victim.

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And yet these lethal fangs must have
caused problems for their owner too.

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How do you eat with teeth this long?

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Even with a huge gape

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almost twice the span of any other cat

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the sabre-tooth could barely
open its mouth wide enough

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to lift these massive canines
clear of its lower jaw.

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That would have made it
very difficult to take a bite.

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But it also had
these special cheek teeth.

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They suggest it ate
through the sides of its mouth,

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slicing off
manageable strips of flesh.

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Even so, the sabre-tooth
must have been forced

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to leave much of its meal
for scavengers.

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The mountain lion with its more modest
canines can eat almost anything

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from mountain sheep to birds
and even plants.

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But today,
like every other desert dweller,

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its main problem isn't food,
it's water.

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Away from the main rivers,

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waterholes are rare
and soon evaporate in the heat

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and it may be months
before they get refilled.

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A real downpour may happen
only once a year,

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but it can have a massive impact.

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Storms don't just sustain life
in the desert,

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they have helped to sculpt
this spectacular landscape.

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Rain runs off bare rock and gathers
in the canyons,

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quickly escalating into flash floods

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that can carry
away huge chunks of rock,

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constantly shaping and reshaping
over millions of years

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creating a dreamscape
of spires and gullies.

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Over these millions of years,
the larger rivers -

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The Colorado, Green and San Juan -

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have carved out canyons up
to one mile deep.

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Water has sculpted the cliffs and
gouged out innumerable caves;

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caves that store a wealth of clues
from the Ice Age past.

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One of the most remarkable cave sites

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was discovered
on the Arizona-Utah border.

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Here, the dry air
preserved piles of evidence,

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not bones or teeth, but dung.

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Football-sized dung balls,

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which dated right back
to the Ice Age,

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carpeting the cave floor
10 metres deep.

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But what colossal beast could
have deposited them here?

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It was the largest of
all Ice Age animals,

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a 10 ton relative of modern elephants,
more than 4 metres tall.

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The Columbian mammoth.

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So, was this cave just a latrine,

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or were the mammoths here
for other reasons -

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to escape bad weather,
or the midday heat?

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Perhaps they used it
as a night shelter,

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or came to visit salt licks,

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like some elephants do
in Africa today.

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No one really knows,

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but this prehistoric dung-pile

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offers plenty of other information
about how Columbia mammoths lived.

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It's mostly composed of grass,

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like elephant dung balls today.

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To get enough food to sustain
their huge bodies,

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mammoths had to graze for up
to 20 hours a day

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consuming up to
a quarter ton of grass.

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When not eating, they were on the move,
in search of fresh supplies.

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They probably migrated through the
river valleys and the bigger canyons,

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careful not to stray
too far from water.

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But the continent these mammoths
travelled through

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looked very different
from the one we know today.

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During the Ice Age,

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much of North America was blanketed

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with massive ice sheets up
to two miles thick.

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And when the great thaw began,

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the changes in the north brought
a new era to the desert.

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For the first time,

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people were able to make
the arduous journey south.

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Today we can still map their route
from stone tools left behind.

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In just a few hundred years they spread
down from the Great Plains,

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through the Canyon lands and
all the way to Mexico.

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They even took
the mighty Colorado river

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and its apparently impenetrable canyons
in their stride.

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Including the Grand Canyon,

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carved out over millions of years,

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this is erosion on an epic scale -

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280 miles long,

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up to 18 wide
and more than one mile deep.

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For people, crossing
this forbidding landscape,

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must have been a superhuman feat.

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But for other animals,

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it seems to be no barrier to travel.

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Up here on the roof
of Canyon lands

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are big horn sheep that seem
to live almost off thin air,

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eking out a living
from the meagre vegetation.

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Specialist desert plants
like cactus offer little nutrition...

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and their defensive spines make
what goodness they do contain

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extremely difficult to reach.

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But the hardy bighorn have evolved to
get all they need from these plants,

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including moisture they need only visit
standing water every few days.

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And the females can still produce
enough milk for their young.

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But 13,000 years ago,

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another climber scaled
these dizzy heights

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and left a clue to its identity

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high in a cave
on the Grand Canyon walls.

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A skull... with vegetarians' teeth...
and short horns.

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It belonged to a mountain goat,

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a common sight here in the Ice Age,

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with a shaggy coat to beat
the biting winds.

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Scenes like this would
have been common back then,

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herds tip-toeing miraculously
across suicidal slopes.

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Now found only
in the Rockies further north,

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they spend most of their time high up
on the mountain slopes,

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but each spring they make their
way down to the canyon bottom,

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where the river has exposed
fresh earth and rock.

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It's a crucial time of year

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the goats are shedding winter coats

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and losing vital minerals with the fur.

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By nibbling these salt licks they can
top up their supplies.

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Even newborn kids must make
the perilous descent

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to collect these crucial salts.

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Other Ice Age creatures also roamed
these precipitous cliffs.

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In this Grand Canyon cave,

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scientists made a remarkable discovery
recreated here.

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Over 200 bones that,
when put together,

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reveal a creature that's been dead
for 13,000 years...

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From measuring these bones we know it
was about as large as a black bear.

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Its teeth have telltale grooves

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that are similar to the tree sloths
still alive today in South America.

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So, what strange beast died here?

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A Shasta ground sloth,

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once as common in the southwest
as the bighorn are today.

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Like the mammoths,

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it left more than bones and teeth
for us to analyse...

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But the ground sloth's
desiccated dung balls

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tell a different story
to the mammoth dung.

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They contain not just grass
but many different plants,

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more than 100 species,

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representing almost every plant
that once grew near the cave.

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The Shasta ground sloth
had a varied menu -

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prickly pear, saltbush and yucca;

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even the tough leaves
of the Joshua tree.

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The dung also reveals
how Shasta ground sloths

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dined on different foods
at different times of year.

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Globe mallow and other desert flowers
only bloom in spring

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but they were obviously gorged on
when available.

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What did the sloths use caves for?

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It's been suggested
they were birthing dens,

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but they may simply have been
sleeping quarters,

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a shelter from the cold desert night.

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One recent study
of the sloths' bone chemistry

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suggests that they were
very sensitive to temperature -

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they may have come inside for warmth.

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But a roof over their head

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was no guarantee
of a good night's sleep.

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Among the Shasta ground sloth bones
was this strange skull

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resembling a mini sabre-tooth

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and from a creature
just as bloodthirsty,

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a vampire bat.

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00:19:27,248 --> 00:19:31,218
Vampires like this one are no longer
found in North America,

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00:19:31,385 --> 00:19:33,821
but once they lived in these caves

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sleeping by day,

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00:19:35,657 --> 00:19:40,428
feeding at night on any warm blood
that they could find.

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00:19:46,566 --> 00:19:51,805
The vampire bat uses tiny sabre teeth
to nick its victim's flesh,

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00:19:52,273 --> 00:19:56,777
then laps the blood by curling up
its tongue into a kind of straw.

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Anti-clotting agents
in the bat's saliva

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keep the blood flowing
until it's full.

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Not all reminders of the history of
Canyon lands are tucked away in caves.

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The open strata of the cliffs reveal
millions of years of geology.

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Each layer represents a chapter
in the story of the past

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all the way back to
the age of the dinosaurs.

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This dark band is slightly different -

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it's not rock,

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but debris from more recent times.

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It's a rubbish dump, or midden,

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made of leftovers
from thousands of small meals,

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all stuffed into the crevice and glued
together with urine and droppings.

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00:21:03,008 --> 00:21:07,645
Who recycled all this debris - and why?

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00:21:10,248 --> 00:21:12,016
It's the desert packrat,

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common all over the Canyon lands.

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00:21:14,886 --> 00:21:19,691
Generations of packrats contribute to
the same middens over thousands of years,

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helping to form a tough protective
shield around their rambling nests.

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00:21:26,630 --> 00:21:29,801
And they help scientists
to look into the past.

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Ingredients like prickly pear spines

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and juniper berries

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reveal just what vegetation grew
across the Canyon lands

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- and when.

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00:21:45,983 --> 00:21:47,451
Thanks to the packrats,

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00:21:47,584 --> 00:21:50,287
we know that the bare rock of
the high plateau

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was once green parkland

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with conifer trees
and lush grassy meadows.

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00:21:59,062 --> 00:22:01,464
There were forests of juniper.

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00:22:02,632 --> 00:22:04,467
And the bare canyon walls were covered

246
00:22:04,601 --> 00:22:08,504
in a rich mosaic of trees and scrub.

247
00:22:10,206 --> 00:22:15,011
Down on the drier plains
Joshua trees flourished.

248
00:22:16,279 --> 00:22:18,581
But the most symbolic
desert plant today

249
00:22:18,714 --> 00:22:21,250
the nine-metre-tall saguaro cactus

250
00:22:21,317 --> 00:22:24,553
was rare 13,000 years ago.

251
00:22:27,223 --> 00:22:30,126
Now there are
spectacular saguaro forests

252
00:22:30,259 --> 00:22:38,033
but back then these broad valleys were
carpeted with oaks, sagebrush and juniper.

253
00:22:39,501 --> 00:22:41,270
Such dramatic changes

254
00:22:41,370 --> 00:22:44,606
tell us it was once
much wetter and milder here

255
00:22:44,673 --> 00:22:46,308
than it is today.

256
00:22:47,342 --> 00:22:49,878
Proof of this damper climate
can be found

257
00:22:50,011 --> 00:22:54,315
and in perhaps the last place
on earth you'd expect.

258
00:23:05,793 --> 00:23:07,461
Death Valley;

259
00:23:08,195 --> 00:23:10,365
100 metres below sea level,

260
00:23:10,465 --> 00:23:13,534
this is the lowest point
in the Western hemisphere.

261
00:23:13,968 --> 00:23:17,505
It's also one of the hottest,
driest places on earth,

262
00:23:17,605 --> 00:23:22,142
with daytime temperatures that soar
to 50 degrees centigrade.

263
00:23:22,242 --> 00:23:25,946
And it may not rain for years
at a time.

264
00:23:27,481 --> 00:23:30,951
Yet even in this furnace,
there is life.

265
00:23:31,251 --> 00:23:35,789
It exists in the many spring-fed pools
that dot the valley floor.

266
00:23:39,693 --> 00:23:41,728
These are desert pupfish

267
00:23:41,862 --> 00:23:43,663
and they manage
to survive in water

268
00:23:43,730 --> 00:23:46,399
several times
more salty than the sea,

269
00:23:46,499 --> 00:23:50,236
sometimes at temperatures of
nearly 40 degrees.

270
00:23:51,137 --> 00:23:54,241
Most pools support
their own individual species

271
00:23:54,374 --> 00:23:57,544
and each pool is their entire world.

272
00:23:57,644 --> 00:24:02,748
This is where they hatch,
feed, breed and die.

273
00:24:05,918 --> 00:24:10,256
But how did tiny fish end up living
in the middle of the desert?

274
00:24:10,857 --> 00:24:12,458
The answer's all around

275
00:24:12,591 --> 00:24:16,628
in the vast salt flats
that separate the pupfish pools.

276
00:24:17,829 --> 00:24:19,998
This is the dry bed
of a huge lake

277
00:24:20,065 --> 00:24:23,035
that existed here
during the Ice Age.

278
00:24:25,671 --> 00:24:29,307
When the climate warmed,
the lake began to dry out,

279
00:24:29,408 --> 00:24:31,710
and the pupfish
only managed to survive

280
00:24:31,843 --> 00:24:34,746
where springs continued
to supply water.

281
00:24:37,015 --> 00:24:38,583
Cut off from each other,

282
00:24:38,717 --> 00:24:43,321
pupfish then evolved into the many
different species found today.

283
00:24:50,962 --> 00:24:53,131
The existence of
this prehistoric lake

284
00:24:53,198 --> 00:24:57,335
proves that the Canyon lands
were once a wetter, greener place.

285
00:24:57,435 --> 00:25:00,070
And that explains
the different vegetation changes

286
00:25:00,204 --> 00:25:03,407
that we see recorded
in the packrat middens.

287
00:25:06,811 --> 00:25:09,914
The lake that filled Death Valley
was huge.

288
00:25:10,181 --> 00:25:12,950
Its waterways, marshes and reed beds

289
00:25:13,050 --> 00:25:16,219
would have been a magnet
for all kinds of wildlife,

290
00:25:16,353 --> 00:25:19,056
and a pit-stop for migrating birds.

291
00:25:23,127 --> 00:25:27,931
Vast flocks of cranes and geese
flew in to winter here.

292
00:25:32,869 --> 00:25:35,205
For several months,
they'd gather strength

293
00:25:35,305 --> 00:25:39,109
before embarking
on the long trip north to breed.

294
00:25:46,849 --> 00:25:48,585
In this rich hunting ground,

295
00:25:48,718 --> 00:25:53,789
the cranes could eat their fill of
fish, amphibians and water plants.

296
00:26:09,171 --> 00:26:11,440
There were larger animals
here as well.

297
00:26:11,640 --> 00:26:14,576
The mild wet climate
and abundant vegetation

298
00:26:14,709 --> 00:26:18,414
made the Canyon lands
an ideal habitat for grazers,

299
00:26:18,514 --> 00:26:22,651
including some that would seem
strangely out of place today.

300
00:26:23,452 --> 00:26:25,286
Camels were very common

301
00:26:25,420 --> 00:26:28,623
and like Columbia mammoths
and Shasta ground sloths

302
00:26:28,723 --> 00:26:31,660
they left plenty of
dung pellet clues.

303
00:26:32,260 --> 00:26:35,263
Dissecting their dung shows
they had a varied diet

304
00:26:35,397 --> 00:26:37,332
from fine desert grasses

305
00:26:37,432 --> 00:26:40,601
to the toughest shrubs and trees.

306
00:26:46,441 --> 00:26:47,775
We may think of bison

307
00:26:47,842 --> 00:26:50,878
as belonging to the open prairies
further north,

308
00:26:50,978 --> 00:26:52,980
but back then
they were equally at home

309
00:26:53,114 --> 00:26:55,582
grazing the valleys of the southwest.

310
00:26:56,350 --> 00:26:57,651
They spent their whole lives

311
00:26:57,751 --> 00:27:01,055
following the rains
in search of fresh grass.

312
00:27:04,291 --> 00:27:06,527
This pattern
of continuous migration

313
00:27:06,660 --> 00:27:09,129
ruled the lives
of many creatures here

314
00:27:09,262 --> 00:27:12,732
including horses similar
to modern zebra.

315
00:27:23,143 --> 00:27:25,211
But 13,000 years ago,

316
00:27:25,478 --> 00:27:28,715
a new threat arrived
in the canyon lands.

317
00:27:38,090 --> 00:27:41,460
These first hunters had
one big advantage:

318
00:27:41,560 --> 00:27:44,897
their prey had little
or no experience of humans

319
00:27:45,031 --> 00:27:48,000
and was therefore easier to approach.

320
00:28:03,415 --> 00:28:05,684
They were armed with flint spear points

321
00:28:05,817 --> 00:28:08,586
and tried and tested
hunting strategies -

322
00:28:08,720 --> 00:28:13,258
working as a team, they were a match
for any desert prey.

323
00:28:41,619 --> 00:28:45,756
The hunters' success wasn't bad news
for all desert creatures.

324
00:28:45,856 --> 00:28:47,858
Their kills must have
provided leftovers

325
00:28:47,992 --> 00:28:50,527
for scavengers like ravens.

326
00:28:53,964 --> 00:28:57,234
Ravens still scan
the Canyon lands for food

327
00:28:57,301 --> 00:29:00,671
and build their nests amid
the pinnacles and towers.

328
00:29:13,783 --> 00:29:15,218
Some of the ravens' ledges

329
00:29:15,318 --> 00:29:19,489
have been found to hold
unique clues to the desert's past -

330
00:29:21,624 --> 00:29:25,095
bone fragments from large animals
like mountain goats,

331
00:29:29,999 --> 00:29:31,400
wild asses

332
00:29:34,336 --> 00:29:35,671
and camels.

333
00:29:37,139 --> 00:29:39,809
But how did they get
all the way up here?

334
00:29:40,176 --> 00:29:42,144
Alongside is the answer,

335
00:29:42,878 --> 00:29:44,613
it's a huge beak

336
00:29:44,847 --> 00:29:46,849
from a giant bird -

337
00:29:48,583 --> 00:29:50,852
an Ice Age condor.

338
00:29:51,686 --> 00:29:53,422
Condors soared across the canyons

339
00:29:53,522 --> 00:29:55,758
on their huge three-metre wingspan,

340
00:29:55,858 --> 00:29:57,759
seeking carrion below.

341
00:30:14,142 --> 00:30:18,079
Condors weren't the only scavengers
13,000 years ago,

342
00:30:18,245 --> 00:30:23,484
but they were big enough to overshadow
many rivals including foxes.

343
00:30:37,732 --> 00:30:40,134
With their immensely strong beaks,

344
00:30:40,201 --> 00:30:43,403
condors could rip through
almost any carcass,

345
00:30:43,503 --> 00:30:47,507
tearing through the hide to
reach the meat inside.

346
00:30:50,244 --> 00:30:54,881
Smaller birds like cara caras waited
for discarded scraps.

347
00:31:13,766 --> 00:31:18,338
Fossils show that many other scavenging
birds cruised the Ice Age canyons

348
00:31:18,438 --> 00:31:21,774
vultures, storks and eagles.

349
00:31:22,341 --> 00:31:24,977
But if they survived by eating carrion,

350
00:31:25,111 --> 00:31:26,712
who was doing the killing?

351
00:31:28,914 --> 00:31:33,853
The fossils also show there was
a front line of top predators:

352
00:31:37,289 --> 00:31:39,625
cheetah - the sprinter,

353
00:31:43,695 --> 00:31:46,564
wolf - the pack hunter,

354
00:31:50,469 --> 00:31:55,140
and lions - bigger and more powerful
than any seen today.

355
00:31:58,876 --> 00:32:03,548
All these hunters generated leftovers
for scavengers to squabble.

356
00:32:10,988 --> 00:32:13,991
But there was one more killer
working these canyons,

357
00:32:14,191 --> 00:32:17,829
the most notorious of
all Ice Age assassins.

358
00:32:28,105 --> 00:32:32,076
Most of what we know about this hunter
comes not from caves,

359
00:32:32,209 --> 00:32:34,712
but from a very different source -

360
00:32:35,212 --> 00:32:37,247
natural tar pits.

361
00:32:44,253 --> 00:32:48,925
A single tar pit has been found
with over 2,000 skeletons

362
00:32:49,025 --> 00:32:51,027
of sabre-toothed cats.

363
00:33:04,941 --> 00:33:07,943
By studying the skeletons pulled
from these pits,

364
00:33:08,210 --> 00:33:13,983
we can piece together how the
flesh-and-blood cats lived and died.

365
00:33:15,952 --> 00:33:18,220
These cats were hugely powerful,

366
00:33:18,320 --> 00:33:21,256
similar in size to African lions today,

367
00:33:21,357 --> 00:33:23,959
but heavier and densely muscled,

368
00:33:24,059 --> 00:33:27,462
weighing 300 kilos or more.

369
00:33:27,697 --> 00:33:31,433
All this and then
the terrifying canine teeth,

370
00:33:31,533 --> 00:33:33,669
which gave the cats their name.

371
00:33:37,272 --> 00:33:42,311
A tiny bone found in the throat
suggests the sabre-tooth could roar

372
00:33:42,411 --> 00:33:45,380
and so perhaps communicate
with its neighbours.

373
00:33:50,985 --> 00:33:53,788
Other bones tell other stories.

374
00:33:56,725 --> 00:33:59,227
Many show some kind of injury,

375
00:33:59,460 --> 00:34:01,796
including broken teeth,

376
00:34:03,431 --> 00:34:05,199
smashed legs

377
00:34:05,733 --> 00:34:07,701
and dislocated hips,

378
00:34:09,937 --> 00:34:13,874
nothing unusual in animals
that wrestled heavy prey.

379
00:34:14,608 --> 00:34:19,213
But what is amazing is that these bones
often show signs of healing

380
00:34:19,446 --> 00:34:22,449
meaning the cats lived on
for months or years,

381
00:34:22,582 --> 00:34:25,018
even when permanently crippled.

382
00:34:25,753 --> 00:34:27,521
But if they couldn't hunt,

383
00:34:27,621 --> 00:34:30,190
how did they stay alive?

384
00:34:32,092 --> 00:34:35,695
Some scientists believe that
sabre-tooths were social animals

385
00:34:35,795 --> 00:34:39,600
and healthy members of the group
supported weaker relatives.

386
00:34:41,701 --> 00:34:42,903
But on the other hand,

387
00:34:43,103 --> 00:34:45,705
they may have simply used
their terrifying looks to

388
00:34:45,772 --> 00:34:47,507
scare smaller hunters,

389
00:34:47,640 --> 00:34:51,644
wolves for example,
away from their kills.

390
00:35:28,780 --> 00:35:30,582
At the end of the last Ice Age,

391
00:35:30,715 --> 00:35:33,751
more sophisticated hunters
started to arrive.

392
00:35:34,886 --> 00:35:38,990
They were about to change the hierarchy
of the Canyon lands forever.

393
00:35:41,259 --> 00:35:42,227
Following the rivers,

394
00:35:42,360 --> 00:35:45,463
feeding on whatever big game
crossed their path,

395
00:35:45,596 --> 00:35:49,833
their small bands quickly spread
across the entire region.

396
00:35:54,338 --> 00:35:56,941
From the moment these hunters
set foot here,

397
00:35:57,108 --> 00:35:59,944
many Ice Age creatures started
to decline

398
00:36:00,044 --> 00:36:01,879
and became destined for extinction.

399
00:36:06,550 --> 00:36:08,152
But they left a trail of hidden clues

400
00:36:08,285 --> 00:36:10,921
throughout the caves and
canyons of the desert,

401
00:36:11,055 --> 00:36:14,758
and each one helps us build
a clearer picture of the past.

402
00:36:15,192 --> 00:36:18,328
And if we can fit
these fragments back together,

403
00:36:18,428 --> 00:36:22,166
we can bring a lost world
back to life.

404
00:36:42,318 --> 00:36:44,286
Combining all this evidence,

405
00:36:44,420 --> 00:36:47,356
we can now go back 13,000 years

406
00:36:47,489 --> 00:36:53,129
and recreate a day in the life of
North America's Ice Age Canyon lands.

407
00:36:56,599 --> 00:36:59,101
The sun breaks
over the rim of the canyons

408
00:36:59,234 --> 00:37:02,103
and begins to warm the cool night air.

409
00:37:06,508 --> 00:37:09,344
An early riser lumbers
through the valley,

410
00:37:09,444 --> 00:37:15,083
and in the marshes along the river,
roosting cranes begin to stir.

411
00:37:18,954 --> 00:37:20,455
The winter's almost over,

412
00:37:21,189 --> 00:37:25,393
they will soon be leaving for the long
flight north to breed.

413
00:37:27,962 --> 00:37:30,331
Others have already stumbled
upon breakfast.

414
00:37:30,898 --> 00:37:35,537
It's a bison carcass
but no meal comes easy.

415
00:37:39,473 --> 00:37:43,544
It takes all the wolves' teamwork
to extract it from the mud,

416
00:37:43,744 --> 00:37:47,215
and even then it's unlikely
to feed the whole pack.

417
00:38:09,302 --> 00:38:14,006
High above, a solitary hunter leaves
her cliff-top den.

418
00:38:20,914 --> 00:38:24,250
From here she can survey
her vast range

419
00:38:24,550 --> 00:38:26,752
she hasn't eaten
for a few days

420
00:38:26,886 --> 00:38:30,490
and she may have many miles to go
to find a meal.

421
00:38:41,667 --> 00:38:43,168
Signs of life,

422
00:38:43,568 --> 00:38:45,671
but out of even her league.

423
00:38:46,072 --> 00:38:49,141
Columbia mammoths graze
the high plateau.

424
00:38:54,613 --> 00:38:56,748
Other members of the herd
are still emerging

425
00:38:56,881 --> 00:39:00,019
from their night-time shelter
in a large cave.

426
00:39:10,161 --> 00:39:14,699
For these ten-tonne giants,
it's a struggle to survive.

427
00:39:18,870 --> 00:39:21,105
This canyon with its sparse vegetation

428
00:39:21,239 --> 00:39:24,108
won't support their massive appetites
for long.

429
00:39:24,175 --> 00:39:26,810
They'll have to move on
in a few days' time.

430
00:39:41,893 --> 00:39:43,427
The sabre-tooth starts to move down

431
00:39:43,561 --> 00:39:46,030
through the gullies to the flats
around the river,

432
00:39:46,130 --> 00:39:48,866
where she knows
there will be far more prey.

433
00:39:54,070 --> 00:39:57,474
Another big cat has the same thing
on its mind.

434
00:40:00,644 --> 00:40:03,113
She too sets off towards the river,

435
00:40:12,722 --> 00:40:14,557
but her path is blocked.

436
00:40:28,070 --> 00:40:30,406
Even a mountain lion
doesn't have the power

437
00:40:30,539 --> 00:40:34,343
or the weapons
to compete with sabre-tooths.

438
00:40:39,282 --> 00:40:41,584
Better to take
the long way round.

439
00:40:58,833 --> 00:41:01,269
With the sabre-tooth
on her way down,

440
00:41:01,302 --> 00:41:04,038
the cliff-tops are a safer place.

441
00:41:06,207 --> 00:41:08,677
By managing to scrape
a living up here,

442
00:41:08,810 --> 00:41:12,480
bighorn sheep avoid the dangers of
the open valley floor.

443
00:41:12,914 --> 00:41:15,550
But even they need water
every now and then,

444
00:41:15,650 --> 00:41:18,586
and have to scramble down
to reach the river.

445
00:41:28,295 --> 00:41:30,864
Some members of the mammoth herd
come down to drink

446
00:41:30,964 --> 00:41:33,834
before they start
the daily grazing marathon.

447
00:41:43,944 --> 00:41:45,045
Once in the meadows,

448
00:41:45,178 --> 00:41:48,548
they mingle with horses
and wild asses,

449
00:41:48,781 --> 00:41:50,550
camels and bison,

450
00:41:51,451 --> 00:41:54,321
all drawn by the spring
flush of new grasses,

451
00:41:54,454 --> 00:41:57,657
flowering plants
and sprouting bushes.

452
00:42:06,933 --> 00:42:10,336
The Shasta ground sloth waits
until the morning chill has gone

453
00:42:10,436 --> 00:42:12,171
before he ventures out.

454
00:42:13,139 --> 00:42:15,441
He comes back to his cave
each evening,

455
00:42:15,574 --> 00:42:19,612
but by day he wanders miles
around the Canyon lands,

456
00:42:19,746 --> 00:42:22,281
dining on anything
that takes his fancy.

457
00:42:39,765 --> 00:42:41,766
The ground sloth's lucky -

458
00:42:41,900 --> 00:42:44,802
he can tackle tougher plants
than mammoths.

459
00:42:44,936 --> 00:42:47,839
In fact, he can eat almost anything.

460
00:43:02,887 --> 00:43:05,690
The sabre-tooth's already hot
on his trail,

461
00:43:05,790 --> 00:43:09,293
but so far the sloth is preoccupied
with breakfast.

462
00:43:20,071 --> 00:43:22,873
Camels browse the trees and bushes.

463
00:43:25,475 --> 00:43:29,713
Like the sloth, they're tempting game
for any hunter.

464
00:43:53,803 --> 00:43:56,405
After taking shelter
in the canyon overnight,

465
00:43:56,539 --> 00:43:59,274
the camels too converge on the river

466
00:43:59,608 --> 00:44:03,146
and must run the risk of
crossing open ground.

467
00:44:06,482 --> 00:44:09,685
Their expedition quickly draws
the sabre-tooth's attention.

468
00:44:11,153 --> 00:44:15,091
They're softer targets than the faster,
more elusive prey.

469
00:44:43,718 --> 00:44:45,120
Once at the river's edge,

470
00:44:45,253 --> 00:44:47,622
the camels are
at their most vulnerable,

471
00:44:47,789 --> 00:44:51,826
hemmed in between the cliff-sides
and the Colorado river.

472
00:45:09,643 --> 00:45:13,514
It will take the camels only minutes
to refill their 100 litre tanks,

473
00:45:13,614 --> 00:45:16,917
but they've been side-tracked by lush
browsing on the riverbank

474
00:45:17,050 --> 00:45:19,920
just long enough to let
the cat catch up.

475
00:45:30,664 --> 00:45:33,466
The sabre-tooth's not built
for long pursuits,

476
00:45:33,533 --> 00:45:35,435
but if she can creep close enough

477
00:45:35,568 --> 00:45:39,005
she'll use a burst of speed
to launch an ambush.

478
00:45:58,824 --> 00:46:03,729
One hit... and one bite...
is all it takes.

479
00:46:03,862 --> 00:46:05,964
The camel is as good as dead.

480
00:46:08,900 --> 00:46:11,003
The cat withdraws out of harm's way

481
00:46:11,303 --> 00:46:14,640
leaving blood loss and shock
to do the rest.

482
00:46:49,473 --> 00:46:52,309
But as the sabre-tooth moves in
to claim her kill,

483
00:46:52,410 --> 00:46:53,845
she's not alone.

484
00:46:55,880 --> 00:46:58,582
A second cat emerges
from the bushes.

485
00:47:01,518 --> 00:47:03,753
This one has a badly damaged leg,

486
00:47:03,854 --> 00:47:05,889
the legacy of ambushing a bison,

487
00:47:06,022 --> 00:47:08,759
and she couldn't possibly
compete for food.

488
00:47:13,363 --> 00:47:17,200
But will the hunter tolerate
another cat at her kill?

489
00:47:26,943 --> 00:47:29,112
These two are not rivals.

490
00:47:29,212 --> 00:47:30,913
They're blood relatives.

491
00:47:31,180 --> 00:47:35,618
The hunter shares her food to help
the injured cat survive.

492
00:47:39,088 --> 00:47:41,390
But even for the fittest
sabre-tooths,

493
00:47:41,624 --> 00:47:45,994
new competition means life is about
to get a lot tougher.

494
00:47:47,496 --> 00:47:50,800
While human hunters quickly find
their feet here in the southwest

495
00:47:50,867 --> 00:47:52,635
and increase their numbers,

496
00:47:52,735 --> 00:47:56,805
sabre-tooths - like many other giants
of the Ice Age -

497
00:47:56,939 --> 00:47:59,808
are now living on borrowed time.

498
00:48:08,684 --> 00:48:11,319
Soon only the ghosts
of these great cats

499
00:48:11,386 --> 00:48:15,623
will haunt the valleys
and plateaux of the Canyon lands.

500
00:48:23,609 --> 00:48:27,387
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