Land of the Sabre-tooth Ice Age Giants


Land of the Sabre-tooth

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Two and a half million years ago,

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life on Planet Earth faced the dawn of a new era...

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..the Ice Age.

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Now we can go back in time...

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..because out of the permafrost,

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from deep inside caves,

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and from hostile deserts,

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the astonishing remains of giant animals are emerging.

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How amazing to be one of the first people to see this ancient creature.

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The Ice Age was the last time such creatures would walk the Earth.

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A lost Eden with mammoths taller than any elephant,

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cats with seven-inch teeth,

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and some of the strangest beasts that have ever existed.

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I'm fascinated by what the remains of ancient animals can tell us

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about THEM, and the world they lived in.

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Using new scientific advances, we can reveal how they lived,

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and why they died out.

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Come with me, back to the Ice Age.

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A world ruled by giants!

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The Great Ice Age was triggered by a combination of natural forces

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acting on a colossal scale.

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Continents moved.

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The planet shifted in its orbit.

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Earth was battered by a merciless cycle of freeze and thaw.

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The last freeze started around 80,000 years ago.

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A vast ice sheet marched down from the Arctic,

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across a continent that today we call North America.

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Known as the Laurentide Ice Sheet, it wiped out everything in its path.

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It advanced down over the continent,

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and life retreated before it.

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No animals or plants could survive on its endless icy plains.

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It might seem like a catastrophe,

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but beyond the ice, incredibly,

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the continent saw an explosion of life...

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..making America the best place in the world

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to discover long-lost giants.

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I'm going south of where the ice sheet once lay,

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searching for megafauna - the great beasts of the Ice Age.

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Where else would you go for an encounter with the ultimate Ice Age celebrity?

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This is the territory of one of the most iconic

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and terrifying animals of the Ice Age.

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This is Los Angeles.

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A place with a surprisingly deep past.

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This glittering city, today the home of movie stars

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and billionaires is also a portal to a lost world.

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Here, we can step back in time

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and meet this awesome creature face to face.

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Smilodon fatalis, a sabre-tooth cat,

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surveys her territory...

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CAT GROWLS

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..some of the richest hunting grounds in the Ice Age world.

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CAT ROARS

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There is something primal and nightmarish about these teeth.

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But exactly how they were used has been a mystery.

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You can't help but be impressed by this fantastic skull and these formidable teeth,

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but this construction presented Smilodon with a problem.

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These teeth are so long and thin

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that they're actually very vulnerable.

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If they were to get stuck in the sinews or the bone

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of a violently struggling animal,

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there's a real danger they could snap.

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It's certainly not a problem faced by any large predator today.

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The big cats of the African plains kill large prey by suffocation.

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Either by smothering...

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..or by crushing the windpipe.

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Remarkably, the canines of a lion rarely even break the skin.

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But Smilodon could not have killed in this way.

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Blaire Van Valkenburgh has spent decades puzzling it out.

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Her evidence points to a method of killing unique to sabre-tooth cats.

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Their teeth were used for stabbing.

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What we THINK is that they went for

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the throat because there is a lot of structures in there

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that make you quite

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vulnerable, such as your windpipe, or jugular vein or carotid arteries,

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these mass of arteries that feed blood to the brain.

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But Blaire needed to figure out how a sabre-tooth cat could

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safely deliver this stabbing death blow.

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How does its skull compare with other big cats?

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A CT scan reveals that the temporal bone, where the jaw

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joins the skull is incredibly thick in a sabre-tooth cat,

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much thicker than in a lion or a cheetah.

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That means a chillingly powerful bite

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and massive jaw muscles.

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To land that lethal bite,

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their mouths could open wide,

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twice as wide as any lion.

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With these canines, they could drive these two things together

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and then pull backwards...

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..and take out a large amount of flesh...

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..making the animal probably bleed to death within minutes.

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A brutal technique that few animals could defend against.

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An American horse.

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To despatch it, this cat must go in hard and kill quickly.

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It's at the moment of the kill

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that the cat's teeth are at their most vulnerable.

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The secret to protecting them lies in its bones.

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Usually what we see in association with having big canine teeth

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like that in these kinds of sabre-toothed species

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is their sort of over-muscled forelimbs.

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They have very heavy, strong forelimbs, like wrestlers.

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And pig paws, too. Their paws are enlarged with big dewclaws, here

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and then they could grasp the prey and hold it steady,

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one paw holding the head, one holding the body,

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and then apply this killing bite, just where they need to put it

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and thereby minimise the risk to themselves of breaking those teeth.

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With these incredibly powerful forelimbs, it would pull down

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its prey before dispatching it

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with these terrifying teeth.

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PREY NEIGHS

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CAT ROARS

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Everything about a sabre-toothed cat, its teeth,

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its killing technique and its muscular body,

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point to one thing - this predator was designed to hunt large prey.

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During the Ice Age,

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sabre-tooth cats flourished right across the continent.

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So America must been full of large animals for them to hunt.

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My next giant may not be as famous as its sabre-toothed predator

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but for me, it's even more extraordinary.

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It inhabited the most spectacular part of America.

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I'm looking for Ice Age secrets in the desert landscape

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of the Grand Canyon.

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This creature left behind something far more revealing

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than just its teeth and bones.

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Hidden somewhere high up amongst these towering walls

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and spires is its lair.

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Thank you!

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Nothrotheriops shastensis - the Shasta ground sloth.

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As large as a grizzly bear.

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She walks on the sides of her feet,

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ponderous as she browses.

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But she has seven-inch-long claws.

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Too dangerous - even for a sabre-tooth.

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THEY ROAR

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With such a huge body to feed,

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she isn't really what you'd expect to find in a desert.

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Jim Mead is a world expert in ground sloths.

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He'll help me track it down.

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Today, in the Grand Canyon,

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a lot of the plants here are either poisonous

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or, like this jumping cholla cactus, covered in vicious spines.

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The hideous spines of the barrel cactus were even used

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by the Aztecs for sacrificing victims.

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A clue as to how the ground sloth survived here lies within its lair.

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To find it, we have to retrace the animal's journey,

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right up into the high canyon walls.

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Are we nearly there yet, Jim?

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A long way!

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As our eyes adjust to the gloom of the cave,

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I can't quite believe what I'm seeing.

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So Jim - what is this, is this what it looks like?

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This is just a pile of dung of a Shasta ground sloth,

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an extinct animal of the Ice Age, and we have a whole pile of it here.

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I just find it utterly unbelievable

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that this ancient animal's faeces are still here.

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I mean, that looks like a piece of relatively fresh dung

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which has just been dried out.

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Why on earth hasn't it rotted away?

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There's no water. It's a totally dry cave.

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And so without the water,

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you don't get the decay to mumify it.

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And it's preserved, and it's preserving

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a very unique record of this animal.

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You can see all these definite twigs.

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It's not a good digester. It's doing a very poor job of digesting,

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which is wonderful for us, cos here's the data.

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It's incredible to be holding the remains of a meal,

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eaten by this giant animal, during the Ice Age.

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The dung reveals that the sloth's menu was richer than

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what's on offer today.

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There were also juniper and single-leaf ash trees growing here.

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But it's still a big challenge for any digestive system.

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A clue as to how the ground sloth survived

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lies with its relatives -

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the ones that didn't go extinct.

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A tree sloth.

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She lives high up in the canopy of the South American rainforest...

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..dining on tough and toxic leaves.

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It will take her weeks to digest them,

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and for precious little energy...

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..which is why sloths are so terribly slow.

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The ground sloths of the Ice Age

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were adapted for THEIR strange diets, too.

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If you could peer inside a ground sloth,

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you'd see a huge fermenting gut.

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A Shasta ground sloth was basically a compost heap on legs.

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It could digest pretty much anything.

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The downside was a sluggish metabolism, just like sloths today.

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But the sloth's dung tells us a lot more than just what it ate.

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It's also a record of one species's struggle for survival

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during the Ice Age.

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So, all of this that looks like sediment is in fact excrement?

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This is all dung, this is all dry preserved dung

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and what you're seeing is the surface here,

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it's probably dating on the neighbourhood of 20,000

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and you're seeing going back through time down into different layers,

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further and further.

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We've obviously got some other animals here

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as well as ground sloths, there are tiny little pellets here, too.

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So what are those?

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These little pellets would be pack rats, little rodents.

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They're also scurrying around in here. And yeah, we'll find a little bit of that.

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But most of this stuff,

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most of this material, that is still Shasta ground sloth dung?

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99% is Shasta ground sloth right here.

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You get this pungent smell, and curiously, it's like a wine.

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The sweeter it is, it's older.

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This is old. Just by the smell, it's old.

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Do you ever think you've seen or smelled too much dung?

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Never! This is wonderful.

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At the back of the cave, the dung really piles up.

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And it's here that the beginning and the end

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of the Shasta ground sloth's story is written.

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-So this is where we're starting to get deeper and deeper.

-Oh, yeah!

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-More and more time.

-It's really building up here.

-Yeah.

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It's all through here.

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Now this is the profile I really want to show you.

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-This is incredibly deep at this point.

-Yeah.

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What we have is a metre and a half

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of almost pure Shasta ground sloth dung.

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If we look at the bottom of the unit,

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so we're looking at about, oh, say 40,000 years ago,

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the sloth dung is kind of telling us

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this is a good time to be in the Grand Canyon.

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Then when we get to THIS point right in here,

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now we're at 23,000 years old and something is happening.

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Oh, so this has changed completely.

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Now we're down into what looks like these little pellets.

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Is this the pack rats again?

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Yeah, all pack rat midden and different plants.

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And then this is about 16,000 years old.

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These dates are really significant

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because this means we are looking at the peak of the last Ice Age and it

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seems that for some reason, ground sloths aren't here at that time.

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That's precisely it, something is going on during the full glacial.

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As the ice reached its maximum extent, ground sloths

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abandoned the Grand Canyon.

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It was too dry for their favourite plants.

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And the drop in temperature didn't help.

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Sloths, with their slow metabolism, would have struggled to keep warm.

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It's easy to imagine chaos as the Ice Age really began to bite,

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with those giant ice sheets descending over half the continent.

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But although the sloth suffered,

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other giants thrived during the Ice Age...

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..none more so than one that used to stalk the badlands of Arizona.

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Back in the Ice Age, not everywhere was cold and dry.

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Large swathes of Arizona were covered in swamp...

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..home to an Ice Age giant that is possibly the weirdest mammal ever.

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So weird that scientists can't even agree quite what it looked like.

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A team from Arizona's Museum of Natural History

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has just found an impressive new specimen.

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The surrounding soil has been dug away

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and the creature, encased in plaster, ready to be moved.

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Dave Gillette is obsessed with these animals.

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Dave, what are these creatures?

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These are animals called glyptodonts.

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They're known for their rigid shell.

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It's quite strange looking at it like this, all covered in plaster.

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How big is the specimen inside that?

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Oh, it occupies almost the entire contents, as far as we can tell.

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Right, so this is a large creature?

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Yes, and it's an upside-down shell so that it's belly up, so to speak.

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Strangely, most of the glyptodonts Dave has discovered

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have been found upside down.

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I can't wait to see what these creatures were like.

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But first, Dave must solve the puzzle of how to get this one

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out of the ground.

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This is all really exciting.

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We're going to more the A-frame out of the way

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and the glytptodont can start its journey.

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It's been here for two million years

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and it's just about to go on its travels.

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The only thing holding this two-ton lump of fossil

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and earth together is the fragile coat of plaster.

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Do you think that the weight is OK, just on these four-by-fours?

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All right.

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Whoo!

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-I feel like - oh, happy day!

-Yeah.

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Goodbye, glyptodont!

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SHE LAUGHS

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This find will join the world's greatest collection of glyptodonts

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at the museum in Mesa.

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Dave pieces together these specimens to get a better

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picture of this bizarre creature.

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Ah, Dave, these are fantastic! Are they all from Arizona as well?

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These are all from same area where we just finished excavating.

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Is this a hand or a foot we're looking at here?

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These are probably digging feet.

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We think that glyptodonts had a very strong digging motion.

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That's wonderful. What's this - is this a tail?

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This is a tail.

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-Each vertebra was protected by bony plates all the way around.

-Yeah.

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And in fact the tail could be a weapon.

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It's incredibly chunky, isn't it?

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It's amazing, yeah.

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And this is a vertebra. This is really odd. It's so peculiar,

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cos I'm seeing bits of anatomy that I kind of recognise

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but it all seems to be a bit twisted.

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It's all very strange-looking to me.

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But it's still a mammal, so you can still recognise it as a mammal,

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even if it is strange.

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A very weird mammal. A very weird mammal.

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So put all the bits together, and what have you got?

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A bony shell with a belly that was covered in soft fur.

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An armoured tail and formidable claws.

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Just one crucial bit missing.

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What would the face of this glyptodont have looked like?

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Well, the face would have been very cheeky, fat on the side.

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The trunk would have extended from the nasal bones

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and extended for a foot or more.

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It had a trunk?

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I think it had a trunk. There's a lot of debate about that but

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I don't see any other feeding mechanism for glyptodonts.

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And do you think the bony arrangement that we can see

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here looks like it would have supported a trunk as well?

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I think it does.

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I see muscle scars on the front of these descending processes.

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That's great. I mean,

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-those are muscles which - in us - make us smile.

-That's right.

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But in the glyptodont, they're about moving its trunk around.

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Well, maybe they could smile a little, too! THEY LAUGH

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It's by far the oddest mammal I've ever seen.

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More like some sort of mythological creature,

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like an enormous armadillo with a trunk!

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Even its teeth are peculiar.

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Look at its jaw - that's wonderful!

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This is spectacular. This is the left jaw, and these are the teeth.

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You see, there are eight teeth -

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all cheek teeth, no canines and no incisors.

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Oh, right.

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Yeah, and each tooth has three lobes.

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You can see there are grooves on the teeth and the ridges.

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So what were they eating with these teeth?

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Well, they were eating soft vegetation

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around the streams and lakes.

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These strange Christmas-tree-shaped teeth

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were made to chew on aquatic plants.

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Dave has found another unusual creature alongside the glyptodont.

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The capybara...

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..a giant rodent that still lives

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in the tropical swamps of South America.

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And in the Ice Age, it shared the Arizonan swamp with glyptodonts.

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So could they swim?

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I'm sure they could swim. I'm sure they could swim

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with other glyptodonts and capybaras

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and other animals in the water.

0:30:130:30:16

Unlike its furry neighbour,

0:30:160:30:19

this glyptodont is a challenge for any predator.

0:30:190:30:23

Slow-moving perhaps, but armoured like a tank.

0:30:290:30:33

A stand-off between two males.

0:30:370:30:40

Each one is a ton of muscle and solid bone.

0:30:400:30:45

THEY SCREECH

0:30:540:30:56

Vanquished, the loser struggles to right himself.

0:31:050:31:08

If a glyptodont died in the water,

0:31:130:31:16

its bloated body would turn belly-up

0:31:160:31:18

and eventually sink down to the river bed...

0:31:180:31:21

..which could explain why so many are found upside down.

0:31:240:31:28

So what turned the deserts into swamp?

0:31:400:31:43

The answer lies with the impact the Great Ice Age had on the world.

0:31:470:31:53

Over the last two and a half million years,

0:32:000:32:04

there has been not just one Ice Age, but around 20 of them.

0:32:040:32:08

Fossils reveal that every time the ice sheet grew,

0:32:170:32:21

the Arizonan marshes expanded and the number of glyptodonts rose.

0:32:210:32:26

And when the ice shrank, their numbers fell.

0:32:290:32:33

The ice sheet was acting like a vast mountain range, two miles high,

0:32:460:32:54

big enough to divert moisture-laden Pacific winds, pushing them south...

0:32:540:33:01

THUNDERCLAPS

0:33:020:33:04

..watering the desert and turning it into a lush wetland paradise.

0:33:110:33:17

Across the continent,

0:33:210:33:23

the Ice Age created new worlds for other giants to exploit.

0:33:230:33:30

And there's one animal in particular that benefited.

0:33:300:33:36

The greatest giant of them all.

0:33:360:33:39

Hidden in the sea mist, on a coastal plain just

0:33:440:33:48

north of San Francisco, some large rocks stand tall...

0:33:480:33:52

..sentinels that still bear witness

0:33:580:34:01

to the wanderings of an Ice Age leviathan.

0:34:010:34:04

State archaeologist Breck Parkman has spent decades examining

0:34:090:34:14

every square inch of these rocks.

0:34:140:34:17

-Look at this.

-It's polished.

0:34:210:34:23

-It is polished.

-What do you think caused it - is it weathering?

0:34:230:34:26

No, actually, I think this is all from animals.

0:34:260:34:28

Every bit of this is from animals.

0:34:280:34:31

Large mammals often need a good scratch,

0:34:340:34:39

perhaps to dislodge unwanted guests, like ticks.

0:34:390:34:43

Breck believes that over a long period of time

0:34:460:34:50

animals have polished these rocks to a shine.

0:34:500:34:53

Have you tested this hypothesis?

0:34:590:35:01

I have. We've worked in the lab, and we have taken samples

0:35:010:35:05

of rocks that were known to be polished by wind and by water

0:35:050:35:09

and by faulting and it doesn't compare.

0:35:090:35:11

We've actually looked at something like three or four dozen

0:35:110:35:15

other ideas, some of which are crazy, you know -

0:35:150:35:17

what happens when kelp moves against the rocks, what happens with

0:35:170:35:22

guano on the rocks, and what happens here -

0:35:220:35:24

and you have to see it, though, and you're seeing it today -

0:35:240:35:26

you have to see it to see the selectivity.

0:35:260:35:28

Where is the polish and where isn't it? And it's these knobs and

0:35:280:35:32

overhangs - it's up to a certain height and doesn't go higher.

0:35:320:35:37

Some surfaces have been worn mirror-smooth.

0:35:370:35:41

Oh, that's amazing. That's a massive area of polish.

0:35:450:35:48

But there's one very revealing bit of polishing.

0:35:540:35:58

Wait until you see this rock!

0:36:030:36:05

So what have we got here?

0:36:070:36:09

Well, we have more polish.

0:36:090:36:10

But look at this. Look at how high this polish is.

0:36:100:36:13

Oh, yeah! That's a bit too high for a sheep.

0:36:130:36:16

And look at this. This is just the beginning.

0:36:160:36:18

this polish goes right on up, right on up as high as I can reach.

0:36:180:36:22

This is close to 14 feet here.

0:36:220:36:24

Oh, so that's too high for a horse or a cow as well?

0:36:240:36:27

You can have a horse sitting on the shoulder of a cow

0:36:270:36:30

and still not do that.

0:36:300:36:32

That's much too high for domestic livestock.

0:36:320:36:35

So this is caused by an animal which no longer exists in North America. So what is it?

0:36:350:36:41

I think it's mammoth.

0:36:410:36:43

And 14 feet is actually the shoulder height of really large Columbian mammoth.

0:36:430:36:48

-Oh, that's just fantastic!

-Isn't it?

0:36:480:36:51

A Columbian mammoth had the same characteristic shape

0:36:550:36:59

as the woolly mammoth, with a domed head.

0:36:590:37:02

But a Columbian was much larger and virtually bald.

0:37:020:37:06

Its tusks were magnificent, much longer than an elephant's.

0:37:120:37:18

The herd arrives at a favourite stop-over.

0:37:340:37:36

A chance to exfoliate and scrape off some parasites.

0:37:430:37:48

Amongst these rocks you can feel the presence of those Ice Age beasts.

0:37:530:38:00

It's almost as though the ghosts of the mammoth are still with us.

0:38:000:38:04

But where were these migrating Columbian mammoths actually going to?

0:38:070:38:13

Surely they didn't come all this way just for a scratch?

0:38:130:38:17

Once again, the Ice Age holds the answer.

0:38:210:38:25

As more and more water froze, there was less to fill the oceans.

0:38:250:38:31

At the height of the last Ice Age,

0:38:360:38:39

the global sea level would have been 120 metres lower than it is today.

0:38:390:38:44

So here on the coast of Northern California,

0:38:440:38:46

the land would have extended out, almost to the horizon.

0:38:460:38:51

The great bay of San Francisco became a vast, verdant valley.

0:39:100:39:17

From the Golden Gate, the land stretched 26 miles out to sea.

0:39:220:39:27

What is now a lonely coastal outcrop, back then,

0:39:320:39:37

was a milestone in a lost land.

0:39:370:39:41

The Columbian mammoths themselves contain clues as to what this place was like.

0:39:430:39:48

Their teeth are like millstones,

0:39:520:39:56

perfect for grinding up two tons of grass every week!

0:39:560:40:00

This land was a vast prairie.

0:40:130:40:15

Today, nearly all of the mammoth's coastal grassland

0:40:190:40:24

lies beneath the waves.

0:40:240:40:27

But there is one fragment left.

0:40:270:40:30

This is Point Reyes

0:40:340:40:36

and it is a tiny fragment of what was once a vast coastal prairie.

0:40:360:40:43

This vegetation is perhaps the closest that we can get

0:40:460:40:50

to what was out there on the coastal plains.

0:40:500:40:53

This is bunch grass and it's incredibly tough stuff.

0:40:530:40:57

It positively thrives on being grazed right down to the ground

0:40:570:41:02

and then it sprouts back again.

0:41:020:41:04

And amongst the grasses, we've got beautiful wild flowers.

0:41:040:41:08

There are irises and buttercups amongst them.

0:41:080:41:11

They look fantastic but they taste horrible.

0:41:110:41:15

And that is an adaptation against being grazed.

0:41:150:41:20

So what we've got here is a heavily grazed landscape.

0:41:200:41:24

Today, the grazer is the cattle.

0:41:240:41:28

Back in the Ice Age, it was the hungry mega-herbivores -

0:41:280:41:32

the horse, the bison and the mammoth.

0:41:320:41:35

Just one Ice Age grazer survives here - the tule elk.

0:41:560:42:02

Such fleeting glimpses of the Ice Age might have been

0:42:130:42:17

all we had, were it not for one truly amazing discovery...

0:42:170:42:24

..one which means we can rebuild Ice Age America

0:42:260:42:31

with all of its creatures - great and small!

0:42:310:42:36

I need to return south.

0:42:400:42:43

This is just so strange. There seems to be a road

0:43:020:43:05

pouring down the side of this hill, and this is asphalt,

0:43:050:43:09

but it's natural asphalt and at the top of it,

0:43:090:43:12

I'm hoping to find some sticky tar coming up out of the ground.

0:43:120:43:17

Now this looks a bit more like it.

0:43:230:43:25

I don't really want to step down here because

0:43:250:43:27

I suspect that this could be quite sticky, so

0:43:270:43:31

let's prod it and see.

0:43:310:43:32

Yeah, look at that.

0:43:350:43:36

We've got some lovely, sticky tar coming up there.

0:43:360:43:40

Natural asphalt or tar is very similar to heavy crude oil.

0:43:420:43:47

In parts of California, it wells up through cracks in the earth.

0:43:480:43:53

Deposits like this drove California's oil boom.

0:43:590:44:02

But in 1913, workers at the Rancho La Brea drilling site discovered

0:44:050:44:11

more than they bargained for - thousands of fossils.

0:44:110:44:15

Extinct giants that had become trapped in the tar

0:44:150:44:19

during the Ice Age.

0:44:190:44:20

Rancho La Brea became the most sensational Ice Age fossil site

0:44:230:44:27

in the world.

0:44:270:44:29

And important new discoveries are still being made.

0:44:310:44:35

In the vaults, there are over three million specimens,

0:44:420:44:47

representing more than 600 different species -

0:44:470:44:51

including the star of the show.

0:44:510:44:55

There are hundreds of sabre-tooth cats - Smilodons - in this collection.

0:44:550:44:59

In fact, as we walk down this corridor, everything

0:44:590:45:03

down here on my left and my right -

0:45:030:45:05

it's all Smilodon as far as the eye can see.

0:45:050:45:09

Smilodon, Smilodon, Smilodon,

0:45:090:45:13

all the way to the end of this corridor.

0:45:130:45:16

And then we turn around and we're into herbivore alley.

0:45:160:45:21

We start with two species of bovid. This is Bison antiquus

0:45:210:45:28

and then on the right here, we are into equus - horses.

0:45:280:45:34

We have two species of horse at La Brea.

0:45:340:45:37

Here is the Western Horse.

0:45:370:45:41

And these are its toe-bones which bore the hooves.

0:45:410:45:46

And then we have three species of sloth.

0:45:460:45:52

And these are perhaps my favourite species of animal actually at La Brea

0:45:520:45:55

after the sabre-tooth cats.

0:45:550:45:58

And right towards the end of this corridor we are going to find

0:45:580:46:03

Paramylodon, or Harlan's ground sloth. Here it is.

0:46:030:46:10

And these are its finger bones. Just imagine the claws that

0:46:100:46:14

then extended from them, quite formidable.

0:46:140:46:18

And we've got two species of the camel family.

0:46:180:46:21

Over here, these are the neck vertebrae of Yesterday's Camel.

0:46:210:46:28

And that's quite impressive but we haven't got onto the four species of mustelid -

0:46:280:46:33

that's weasels and badgers, and the three species of rabbit,

0:46:330:46:37

the two species of deer, two species of antelope,

0:46:370:46:40

two species of elephant, one of tapir and one of peccaries.

0:46:400:46:44

And that's not even counting the small mammals.

0:46:440:46:47

Each creature is helping to populate that empty Ice Age landscape.

0:46:530:46:58

And the tar keeps on revealing

0:47:110:47:13

more about the land of the sabre-tooth cat.

0:47:130:47:17

A few years ago, the Museum of Art over there next to the tar pits

0:47:200:47:23

decided it wanted an underground car park,

0:47:230:47:26

but there are tar pits over there as well.

0:47:260:47:29

So the palaeontologists were called in,

0:47:290:47:31

and rather than rush through an excavation there and then,

0:47:310:47:34

they took the sediment out en bloc,

0:47:340:47:37

and brought it back over here in these massive wooden crates

0:47:370:47:40

and now they're carefully excavating each one of them.

0:47:400:47:43

The place feels more like a trailer park than a palaeontological dig!

0:47:570:48:02

'Each box is excavated, grain by grain,

0:48:100:48:13

'by its own resident palaeontologist.'

0:48:130:48:16

-Laura.

-Oh, hi.

-Hello.

-Hi.

0:48:210:48:25

Welcome to box one!

0:48:260:48:28

Laura has been here for nearly a year.

0:48:280:48:33

What are you actually excavating here? It's a real mass of bones.

0:48:340:48:37

It really, really is.

0:48:370:48:38

It's just a kind of a tangled mess at this point.

0:48:380:48:41

Um, but I've got baby bison, maxilla, so, front of his face.

0:48:410:48:44

This one here, you can see his teeth down there.

0:48:440:48:47

-And from more teeth, I got dire wolf, lower jaw.

-Yeah.

0:48:470:48:51

'So far, she's got through two metres of bone deposits.'

0:48:510:48:55

It's painstaking work.

0:48:550:48:56

-But it's fun! I get to dig for buried treasure for my job.

-Yeah!

0:48:560:49:00

This whole project, Project 23 -

0:49:000:49:01

what's the most exciting thing that's emerged from it so far, do you think?

0:49:010:49:05

One of my favourite things anyway is from box 1.

0:49:050:49:08

We have...we kind of nicknamed our own entire family of sabre-tooth cats.

0:49:080:49:12

So far, just from this one deposit right here,

0:49:120:49:15

we have at least three adults, three sub-adults - teenagers,

0:49:150:49:19

and four separate sabre-tooth kittens.

0:49:190:49:22

-Kittens?

-Like you can see right here.

-Sabre-tooth kittens!

-I know!

0:49:220:49:25

Let's see, I have sabre-tooth kitten.

0:49:250:49:27

Ulna. So that's one of the forearm bones.

0:49:270:49:29

We've got more sabre-tooth kitten, we have a thoracic vertebrae.

0:49:290:49:32

Middle of his back.

0:49:320:49:34

And let's see, just over here, that's half from the pelvis.

0:49:340:49:38

This one's from an adult sabre-tooth cat.

0:49:380:49:40

In fact, there's this one day that I actually found three separate

0:49:400:49:43

sabre-tooth kitten sabres all in one day.

0:49:430:49:45

I must admit, that's probably one of my favourite days here.

0:49:450:49:48

The kittens' remains are being scrutinized

0:49:530:49:56

by La Brea sabre-tooth cat expert Chris Shaw.

0:49:560:49:59

These are the most recent sabre-tooth cat bones

0:50:040:50:07

that we have gotten from their project here.

0:50:070:50:11

And these kittens are fantastic.

0:50:110:50:13

We've got their little milk teeth, sabres.

0:50:130:50:15

-Those are the milk teeth.

-Can I pick that one up?

-Yes, you may.

0:50:150:50:19

-Thank you.

-These are the real thing.

-Wow!

0:50:190:50:21

And you'll notice, too - if you rub your finger along the edge

0:50:210:50:25

-of that, it's actually serrated and very sharp.

-Ooh!

0:50:250:50:30

-That's like a knife blade.

-Exactly.

0:50:300:50:32

These animals could puncture skin much like the adults.

0:50:320:50:36

You can feel those...I can barely see those serrations,

0:50:360:50:39

they're really tiny, aren't they?

0:50:390:50:41

-But I can certainly feel them, rubbing my finger along it.

-Yes.

0:50:410:50:44

And these teeth grow in,

0:50:440:50:46

and were actually erupted at the time of birth.

0:50:460:50:50

It's unlikely that the kittens used their sabre teeth to kill.

0:50:520:50:56

Their serrated teeth were like steak knives,

0:51:060:51:09

ideal for scavenging after Mum had made the kill.

0:51:090:51:13

The sheer number of specimens here gives scientists

0:51:160:51:20

the chance to understand not only the anatomy,

0:51:200:51:23

but the behaviour of these extinct cats.

0:51:230:51:26

And one find, in particular,

0:51:290:51:31

is transforming our understanding of how sabre-tooth cats behaved.

0:51:310:51:35

It's a disfigured pelvis,

0:51:370:51:40

one that shows signs of a condition that I've seen before - in humans.

0:51:400:51:46

This is one of my favourite specimens.

0:51:460:51:49

What you have is a very, very nasty injury, and a massive,

0:51:490:51:52

massive infection.

0:51:520:51:54

This...I was going to say,

0:51:540:51:55

this looks to me like septic arthritis.

0:51:550:51:58

This looks like the type of bone growth that you get around a joint which has become infected.

0:51:580:52:03

It's exactly that. And the femur itself, the thigh bone, is really,

0:52:030:52:07

really worn down.

0:52:070:52:08

That's just quite shocking. I mean, this would have been an animal

0:52:080:52:11

-which was limping.

-Right, exactly.

0:52:110:52:12

This animal wouldn't have been able to run after prey,

0:52:120:52:15

and yet we can say, looking at this,

0:52:150:52:17

-this has been a long-standing condition.

-Absolutely.

0:52:170:52:20

For all of this bone to have grown to this extent,

0:52:200:52:24

this animal has survived for months

0:52:240:52:26

and possibly even years with this going on.

0:52:260:52:29

That's absolutely correct and that's the premise of my idea,

0:52:290:52:33

that these animals were in fact social animals.

0:52:330:52:36

That would enable this animal to survive because the rest of the group would bring in the food

0:52:360:52:42

and nurture this animal by letting it feed at kills.

0:52:420:52:48

So not only did this giant cat possess daggers for teeth,

0:52:520:52:57

it's likely that it hunted in groups, much like lions today.

0:52:570:53:01

Sabre-tooth cats must have been utterly terrifying.

0:53:070:53:11

A herd of Columbian mammoths

0:53:160:53:19

is making its annual migration from the coast.

0:53:190:53:23

A young male wanders away from the herd...

0:53:230:53:27

..straight into the path of a pack of sabre-tooth cats.

0:53:300:53:36

But the tar makes it impossible for them to escape.

0:54:190:54:22

This is their last meal.

0:54:240:54:27

The tar has preserved dramatic stories of Ice Age giants.

0:54:370:54:43

But it also holds clues to the world they lived in.

0:54:430:54:47

Hidden amongst the giant bones are much smaller ones.

0:54:510:54:55

And it's these microfossils that can tell us just why this place

0:55:020:55:07

was such a happy hunting ground for sabre-tooth cats.

0:55:070:55:12

Tiny animals like snails and beetles are very sensitive to climate.

0:55:170:55:22

So these species are the best indicators of what the lost

0:55:260:55:30

Ice Age environment was really like.

0:55:300:55:34

What we find is that this area of Southern California was in fact

0:55:340:55:38

cooler and wetter and more lush.

0:55:380:55:42

A beautiful, temperate parkland of open areas

0:55:460:55:50

and woods, populated by these magnificent animals.

0:55:500:55:55

For America, the Ice Age

0:56:230:56:26

was actually the golden age of megafauna.

0:56:260:56:30

But meanwhile, in the rest of the northern hemisphere,

0:56:430:56:47

the ice sheets were going to have a very different impact.

0:56:470:56:51

The most bitter struggle that the Ice Age animals would face was

0:56:560:57:01

not in North America but here, on the other side of the Atlantic

0:57:010:57:06

in the mountains and plains of Europe and Siberia.

0:57:060:57:10

Here, the Ice Age hit with brutal force.

0:57:150:57:19

Next time, I witness the struggle to survive.

0:57:220:57:26

Deep within a cave in Transylvania,

0:57:280:57:31

grisly remains tell of a spectacular fight to the death.

0:57:310:57:36

THEY ROAR FEROCIOUSLY

0:57:360:57:38

And the woolly mammoth faces its own battle for survival

0:57:400:57:44

against a new and cunning predator.

0:57:440:57:46

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