Fugitive from the Fire Survivors: Nature's Indestructible Creatures


Fugitive from the Fire

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Since the emergence of life, more than 3 billion years ago,

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life on our planet has suffered a series of devastating mass extinction events.

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These have killed off uncountable species,

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and even threatened to end life on Earth altogether.

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I'm Professor Richard Fortey, of London's Natural History Museum.

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I've spent all my working life studying the remains of animals long extinct.

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'But now, I'm leaving the vaults

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'to discover why some animals and plants have survived.'

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Hello, snakey.

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'I'm going in search of living fossils,

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'old-timers...'

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This little face.

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'..that somehow managed to survive when so many others perished.'

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Rubbery hardly does it justice.

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'In the process, I hope to find an answer to a profound question.'

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Is being a survivor a question of having some very special features?

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Or nothing more than pure chance?

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'From living fossils that are our most ancient relatives...

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'..to gigantic relics from the age of the dinosaurs.'

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Life as we see it today is not just the product of evolution,

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it's also a consequence of mass extinction.

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We are all the sons and daughters of catastrophe.

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Oh, my goodness!

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More than 100 million years ago, the Cretaceous Age already had

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highly sophisticated and complex ecosystems.

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There were flowers, and plants that we might recognise.

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There were insects, birds and even tiny mammals,

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though not yet butterflies or bees.

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And there were amphibians and reptiles,

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especially very big reptiles, like dinosaurs.

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Then, one day, 65 million years ago,

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this world came to a sudden end

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when a 10km-diameter asteroid collided with the Earth.

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The impact is believed to have struck the Earth

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with the force of 96 teratonnes of TNT,

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causing colossal shockwaves,

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tsunamis perhaps hundreds of metres high

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and so much hot ash and debris, the global atmosphere became superheated,

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igniting wildfires all over the world.

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It was the end of the long reign of the dinosaurs.

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I used to walk with dinosaurs or, more accurately,

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pass them every working day on the way to my office

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in London's Natural History Museum.

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But what I want to know is, what were the lucky breaks

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and evolutionary adaptations that allowed some species

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to survive the disastrous end of the Cretaceous Age

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when these marvellous giants did not?

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Locating the scattered survivors of the KT extinction

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is not as straightforward as you might imagine.

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'You never know quite where they'll turn up.'

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OK, 42nd Street.

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'The survivor I am looking for not only outlived the dinosaurs,

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'but apparently several of them even survived the dropping of the atom bomb on Hiroshima

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'at the end of World War II.'

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Well, this is a jungle of sorts,

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an urban jungle.

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We are right in the middle of Manhattan,

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but even here, lurking in some corner, there might yet be a survivor.

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There's hardly any space here for anything green.

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In fact, hardly any space for anything living,

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except lots and lots of human beings.

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Strangely enough, there's one over there.

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If something can survive the pollution and the heat

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of a summer in New York, not to mention miscellaneous garbage,

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then that is a pretty tough organism.

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And that's exactly where we find the gingko.

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Ginkgo leaves are fan-shaped or triangular, really beautiful leaves,

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combining a perfect design and a certain toughness,

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which may of course have helped them through these crises.

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Gingko trees can now be found

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all over the world.

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But until two centuries ago,

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they could only be found in one isolated region of China.

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Sometimes living for more than a thousand years, they're extremely tough.

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The gingko tree is an example of perhaps the simplest survival strategy of all.

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If you're tough enough to cling on somewhere,

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even a tiny area in one part of the globe,

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a chance may yet come to recolonise the world.

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The KT event was so destructive,

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it reduced even this tough species

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to a tiny rump population clinging on in one remote location.

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So, it may not be surprising

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that nearly half of all animal and plant species

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perished in the destruction.

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What is perhaps far more surprising is that

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relatives of the dinosaurs managed to survive.

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In Queensland, Australia,

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I prepare to meet one of the largest animal survivors

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of the KT extinction event.

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Guys, look, what I'm going to do this afternoon is

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I'm going to dispel the difference between fact and fiction about these animals.

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Now, what most people see...

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Crocodiles are found in tropical climates all over the world.

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The croc is a formidable predator

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that's responsible for the deaths of 2,000 people annually...

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..a fact that handler Clay Mitchell is acutely aware of.

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A male saltwater crocodile can grow to be seven metres long

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and weigh up to 1,000 kilos.

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It's a survivor for whom surprise and ferocity are key weapons.

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Its jaw can snap shut at lightning speed

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and its mouth is filled with 66 hollow teeth.

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These are constantly being renewed by fresh replacements growing inside them.

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A single crocodile can get through an incredible 2,000 teeth in its lifetime.

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And since the oldest crocodile in captivity survived until it was 140 years old,

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well, you can see why it's got such a lot to smile about.

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Go on.

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We might let him get his breath back, eh?

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LAUGHTER

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It's not easy to teach a crocodile new tricks.

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But then, it doesn't need them.

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Crocodiles have remained unchanged since the Jurassic Age,

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the golden age of the dinosaurs that began nearly 200 million years ago.

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They are cold-blooded, highly efficient killing machines

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and, above all, they can wait.

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If pushed, it's not fussy about what it eats.

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I mean, I know it'd eat us if it's feeling a little bit peckish.

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So, it could survive on anything from the small to the humongous.

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It's a tremendous advantage to be able to feed only occasionally and then well,

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and when you get something not to let it go. Cos...

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if you can go without food for six or seven months, you can weather a crisis.

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A born survivor, this one.

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Being able to eat almost anything,

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it's a good way to stay alive in lean times.

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But to get through utter devastation you need something more.

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The question we really want to know is,

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why did this particular kind of animal come through the big crisis

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at the end of the Cretaceous

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and dinosaurs, their contemporaries,

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in some ways more superbly adapted, you might say, didn't make it?

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I think probably one would be its ability to utilise food

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a lot more efficiently than us.

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These guys have got a very slow metabolism,

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so a little bit of food goes a very, very long way.

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So I could probably definitely say he could survive

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for eight or ten months without eating absolutely anything.

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And probably versatility might have been a factor too.

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They've got this famous structure, the nictitating membrane, isn't that right?

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-That's correct.

-It sounds vaguely obscene, doesn't it?

-Ha-ha, it does.

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Perhaps you could explain what that is.

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It's very simple. Look, they have three eyelids.

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So what they do is they have a top one and a bottom one,

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and the nictitating membrane is one that actually moves on the inside of those two eyelids

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from the front of the eye to the back of it.

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When they go under the water and do these sorts of things,

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that nictitating membrane does move across the eye.

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So, the minimum exposure position is basically just to have that nasal disc

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with the two nostrils above the water

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-and you can see how the eyes project at about the same height.

-Yeah.

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So, all they need is to be able to see and to be able to breathe,

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and the rest of the body can remain completely concealed below the water.

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One of the reasons crocodiles survived and dinosaurs didn't

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may be because the same skills that made it such a master of ambush by hiding underwater

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also saved it from the fiery devastation that swept across the world.

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Of course, just to point out one thing, which you said it was half tail.

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That half tail contains some meat, and the meat is presumably quite edible.

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-Definitely.

-So, perhaps we should go and try it.

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Yes. Well, I'd say, I think our chef does a pretty good job with it.

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I think it's actually a meat with a little bit of bite.

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THEY LAUGH

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'I have to admit that I'm curious to try eating crocodile.

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'After all, it's almost like eating dinosaur.'

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-You might as well try one of those, mate.

-All right, let's see. It's a... ha-ha...

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Cheers, mate.

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Mmm...

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Mmm...

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It's pretty good.

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Meaty, succulent.

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It's sort of, um... more pig than fish.

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In fact, you might call it Jurassic pork.

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He-he-he! Certainly.

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All it takes is usually some celebrity chef to get on

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and actually do a little bit of a dish to actually encourage

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people just over that fence to go out there and actually try it for themselves.

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The more people that try it, I think, the more popular it will actually become.

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65 million years ago,

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it wasn't just dinosaurs that got exterminated by the impact.

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Perhaps as many as half of all plant species were also blasted, never to return.

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Some of the same survival strategies the apply to animals like the crocodile

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were also appropriate for the plant world.

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Plants that survived the KT also needed ways to hide out and bide their time.

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One way to survive a disaster is to go NUTS!

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These podocarp seeds are extremely tough, durable time capsules

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that can fall to the ground and germinate after the KT events had passed over them.

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The shell on a nut is a good way to protect a seed from fire,

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but some ancient species have even adapted to endure periodic fires

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as part of their life cycle.

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Such species include many cycads.

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Which is why I'm going to meet cycad expert and enthusiast Gary Wilson.

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'Gary leads me down to the forest trail on a cycad safari.'

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Well, that's quite a tree.

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And I suppose it might be quite old.

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Yes, certainly.

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This one I would suggest, and it's a little difficult to age them, 400 or 500 years, perhaps.

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To an untutored eye, it might look a bit like a palm tree,

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but it's not related to a palm, is it?

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This is one of three types of cycads that is found here

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in this Wet Tropics Region in Daintree, in North Queensland.

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In that way it's a living laboratory

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for these evolutionary survivors across time barriers and extinction events.

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This is a green dinosaur.

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This predated the dinosaurs and has survived them.

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I think they've even found masticated remains of these things...

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-That's correct.

-..in dinosaur coprolites or dinosaur poo, fossilised.

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And found cycad fragments inside, so this was part of dinosaur diet.

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-They went, but their food plant survived.

-Survived.

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And that's an interesting question.

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Any theories particularly why?

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The strategy that ensured the success of the cycads as a group of plants is this,

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it's a time machine, it's a seed.

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It contains a nutrient reservoir.

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It contains an embryo, it can travel through time,

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through seasonality, through extreme events.

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Cycad seeds from some species even need fire to reproduce.

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With rainfall, nutrients in the ash trigger germination.

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'To ensure its survival, the cycad fruit has evolved an additional strategy -

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'poison.'

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It contains a suite of novel compounds that make it unattractive to things eating it, for instance,

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or that would be eating it.

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Cycads are the only plants on the planet

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that incorporate mercury in their tissue.

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-That's very nasty indeed, isn't it?

-Very nasty.

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'More delicate plant survivors needed subtler tactics to survive the KT crisis.'

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In my own garden is a survivor that only made it because of a helping hand.

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Or should I say proboscis?

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Magnolia blossom announces itself from afar

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like a small flock of pale, untidy birds that have become entangled in the branches.

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When this first evolved,

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this plant was pollinated not by the bees and butterflies

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that we are so used to today, but by beetles and other insects.

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'The first magnolias appeared around 100 million years ago.

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'And a few days each year, it's still visited by its ancient pollinators.'

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Got it! Look, look, look, look, look! There they are.

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There's our little beetles.

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Isn't that nice?

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There's one going up the petal.

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Without these tiny insects, flowering plants could not have survived.

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Indeed, the survival of insects and other small invertebrates

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was crucial to the survival of many other species.

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Even so, the early flowers and their pollinators both only just scraped through.

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Why did it survive? Well, it was pollinated by beetles and other insects.

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Those insects carried through too and survived that big extinction event.

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But also it had seeds. And the seeds could survive in the soil.

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They didn't need to germinate every year. Perhaps they could outlive the hard times.

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And I don't think its antiquity has diminished its beauty one iota.

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Even those few plants that made it were ravaged and stressed.

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As plant species after plant species withered and died,

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so too the giant herbivorous dinosaurs also vanished.

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And, in turn, the carnivorous dinosaurs that preyed on them.

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To survive, many animals also needed to behave a little like seeds,

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going underground and quietly enduring.

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A strategy like this may well have saved the snakes.

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'Snake handler Shane Neal has agreed to show me

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'a few of the snake family's more illustrious members.'

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-Hello, Shane.

-Hello, mate.

-Nice to see you.

-Nice to see you too.

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-I gather you've brought me a load of different snakes.

-I have, indeed.

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-Can we have a look?

-Absolutely.

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-Ah! Now, that's an impressive snake.

-It is indeed.

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-What do we have here?

-This is an olive python.

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Would you like to hold it?

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-Ah... Is this the one that likes to be held?

-It is one.

-Oh, all right.

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-Do you trust me?

-Sure, I trust you. Yeah.

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OK.

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And this one is any... Well, as you can see, it's a constrictor.

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It is indeed, yeah.

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-That throttles its, uh...its prey.

-A-ha.

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-Of whom I am not one.

-You hope.

-I hope.

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Could I see where the head is right at the moment?

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-Right beside you.

-All right, OK.

-It's just here.

-Hello, snakey.

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Um... I think, compared with the other snakes,

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am I right in saying that these are comparatively primitive?

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They are indeed. These are probably one of the first constrictors.

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Back in the prehistoric times they used their power to overcome their prey.

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'Snakes are descended from lizard-like reptiles

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'that lost their legs during the Early Cretaceous,

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'some 90 million years ago.

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'This giant python is one of the more ancient living snakes.'

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This is probably the second largest python we have in Australia

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and they could take anything, maybe even a full-grown wallaby.

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And when they've eaten a full-grown wallaby,

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how long is it before they have to eat again?

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Well, it'd vary on temperatures and what kind of climates,

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-cos the hotter it is the more... quicker they actually back down.

-Yes.

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But, like all reptiles, they could go months and months and months

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before they even need another feed after a big one like that.

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Well, this is kind of relevant to our thoughts about survivors.

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You could imagine a scenario at least where you've got something

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-which would go without food for a long time and burrow.

-That's definitely a...

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Which would be a pretty...secure environment for them to survive a crisis.

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Absolutely.

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And, um... Am I ever going to extract myself from this situation?

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I'm not quite sure.

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Well, some venomous snakes of course are almost ludicrously poisonous, aren't they?

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There's only one poisonous snake in the entire world, and that's the sea snake.

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The rest are venomous.

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Oh, I beg your pardon. Yes, venomous. That's exactly right.

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Of course, I should have remembered,

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poison is ingested into the system, whereas venom is injected directly by fangs.

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-Perhaps we should look at one of the other ones.

-Absolutely. Indeed.

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-See where he's going already.

-There we go.

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He could have you, not a problem.

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-He could have me, not a problem.

-A-ha.

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The ancestors of the python may well have survived

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because they could swallow one big meal and wait.

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But if you only eat once a year, you need to make sure your attack is effective.

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'Constriction is one method to immobilise your prey

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'and venom is another.'

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Now, that's an impressive snake.

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'Recent genetic studies suggest that this is a very ancient weapon

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'and that the first venomous snakes evolved during the time of the dinosaurs.'

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The most venomous snake in the world is the legendary taipan, and...

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If I go like this a little bit...

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Yeah. I'm not going to take any chances with this one, and...

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-This is it.

-There's a legendary statistic about this particular snake.

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It's so venomous that one bite would kill how many human beings?

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About 300 men.

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Which leads one to the question of why any snake has to be so venomous.

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It would probably have a lot to do with what it eats.

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Now, no-one is 100% sure but, I mean, when it comes to venom,

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cos venom is just modified saliva.

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It actually just works a lot better on warm-blooded animals,

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whereas things like fish, amphibians, and even other reptiles,

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they generally need a much higher dose, and that's actually what these guys feed on.

0:23:130:23:17

So it's a case of, it may seem extravagant,

0:23:170:23:21

but actually it's just right.

0:23:210:23:24

That's right. It's perfect for what this animal actually needs.

0:23:240:23:27

Good. Well, that's answered a question which has been bothering me for some time.

0:23:270:23:33

'Such potent venom is surely a guarantee of success,

0:23:330:23:37

'especially in hard times when you can't afford to miss a kill.

0:23:370:23:40

'Snakes could have survived the KT by hiding away and feeding only rarely.

0:23:400:23:45

'But how my next survivor made it through the extinction is more of a mystery.'

0:23:450:23:52

Quack, quack, quack! Come on.

0:23:530:23:55

How did the ancestors of today's birds survive the KT impact?

0:23:550:24:01

They couldn't just fly away from a ubiquitous catastrophe,

0:24:010:24:04

although having wings may have helped them reach a refuge.

0:24:040:24:08

Some aquatic birds might have survived out to sea,

0:24:080:24:11

or maybe some land lovers burrowed to escape the immediate effects of the catastrophe.

0:24:110:24:17

Feathers would have been useful insulation in the cold climate

0:24:180:24:21

that followed in the months, even years, after.

0:24:210:24:25

But then, many dinosaurs also had feathers and didn't survive.

0:24:250:24:29

So that can't be the explanation.

0:24:290:24:31

It seems most probable that birds could brave the hard times

0:24:340:24:37

because they survived on insects and small fish, other survivors.

0:24:370:24:42

And their flight buoyed them through from meal to meal and place to place.

0:24:420:24:46

But if the survival of their foodstuff

0:24:580:25:00

was one of the possible reasons why birds were saved from extinction,

0:25:000:25:04

if you're a bird that can't fly, you would have needed different strategies.

0:25:040:25:09

The emu is from a primitive family of birds called ratites,

0:25:110:25:16

that also includes ostriches, kiwi and cassowaries.

0:25:160:25:18

Emus have flightless feathers

0:25:270:25:30

and blade-like claws that closely resemble those of the three-toed theropod dinosaurs

0:25:300:25:35

from which they are ultimately descended.

0:25:350:25:38

They also have a reputation for aggression.

0:25:380:25:41

Females fight over males to breed.

0:25:430:25:45

Those prepared to get up close to an emu,

0:25:470:25:50

like our soundman, can only hope they are not mistaken for a rival.

0:25:500:25:54

Fortunately, James Biggs is a young man brave enough to be my guide.

0:26:080:26:12

-Well, I gather you... there's Mr and Mrs here.

-Yeah.

0:26:210:26:25

And Mrs has a, what should we say,

0:26:250:26:28

slightly more ferocious temperament than Mr, is that right?

0:26:280:26:31

Yeah, that's right.

0:26:310:26:33

So, as somebody who's looked after these creatures for a long time,

0:26:330:26:37

would you say they're, um... Would you describe them as intelligent?

0:26:370:26:41

Ha-ha-ha! No.

0:26:410:26:43

Instinctive, reactive, but definitely not intelligent.

0:26:430:26:48

Well, but they are survivors.

0:26:480:26:52

Emus might not be bright,

0:26:520:26:54

but they have a series of key survival traits.

0:26:540:26:57

They reach full size in only six months

0:26:570:27:00

and can live to be, well, perhaps 20 years old.

0:27:000:27:04

But the real secret of their success is that females don't put all their eggs in one basket.

0:27:040:27:10

They leave the males holding the babies.

0:27:100:27:14

-And the male incubates the eggs?

-He does. He incubates the eggs, he raises the chicks.

0:27:140:27:19

The female, apart from laying the egg, has nothing to do with the raising of the offspring.

0:27:190:27:26

Well, of course, I knew one or two human beings rather like that. But it's not the rule.

0:27:260:27:30

For ratites, I guess it seems to be.

0:27:300:27:33

Particularly in the breeding season, the male can go for weeks without food

0:27:330:27:38

whilst he's incubating the eggs.

0:27:380:27:40

-Well, actually, that is a survival technique, isn't it?

-Yes.

0:27:400:27:44

Let's face it, if times get hard, if you don't have to drink for weeks on end,

0:27:440:27:49

-you can travel a great distance in search of either food or water.

-Yeah.

0:27:490:27:55

By spreading her eggs around multiple males, and multiple nests,

0:27:550:27:59

the female emu increases the chance of at least some of her offspring surviving.

0:27:590:28:05

The turtle is a creature that does the opposite.

0:28:140:28:18

It puts all its eggs in one very big basket.

0:28:180:28:22

On average, only one out of every thousand of these baby turtles is likely to reach adulthood.

0:28:260:28:32

And yet, this very different strategy has long worked for the turtle.

0:28:350:28:40

After the KT impact, the seas became poisoned

0:28:460:28:50

by the fallout of toxic debris and ash.

0:28:500:28:53

Turtles had already been around for more than 150 million years.

0:28:580:29:04

Some had even evolved into four metre long giants.

0:29:040:29:07

But the KT extinction event would reduce their numbers

0:29:090:29:12

and their size.

0:29:120:29:14

'Doing her bit to maintain the turtles' long track record of survival is Jennie Gilbert,

0:29:170:29:23

'who runs a turtle rehabilitation centre.'

0:29:230:29:27

So, who have we got here?

0:29:270:29:29

Her name is Angie and she's actually a mature female olive ridley.

0:29:290:29:33

-And that's one of the rarer turtles?

-It is.

0:29:330:29:36

She is one of the rarer turtles.

0:29:360:29:38

I can see some tooth marks.

0:29:380:29:41

Yes, she got bitten on the top of the shell as you can see.

0:29:410:29:44

She actually was attacked by a very large saltwater crocodile.

0:29:440:29:47

And she also had part of her jaw hanging off.

0:29:470:29:51

So we had to take that piece of jaw off.

0:29:510:29:54

That proves that if a crocodile can snap at this poor animal

0:29:540:30:00

and the animal survives, it shows how tough she is.

0:30:000:30:02

Exactly right.

0:30:020:30:03

That shell must be incredibly tough for her to survive through that.

0:30:030:30:07

If you think of the size of a large saltwater crocodile, about 17 ft,

0:30:070:30:12

and he has come down with his jaws on top of her

0:30:120:30:14

and she's got out of it, she's a pretty tough girl.

0:30:140:30:17

To examine just how tough, I want to dig deep into the anatomy

0:30:210:30:25

of a recently deceased turtle found on a local beach.

0:30:250:30:28

Here's our turtle. How old do you think?

0:30:300:30:33

She's probably about 60-plus years.

0:30:330:30:36

-And it's a...green?

-Green, mature female.

0:30:370:30:40

This is called a plastron and it's a series of plates, as you can see.

0:30:400:30:45

-Extremely tough.

-Extremely tough.

0:30:450:30:47

But it's not as tough as the carapace which is on the top.

0:30:470:30:50

As you can feel, the carapace is very, very tough and bony.

0:30:500:30:54

'The turtle's shell is a very obvious survival trait,

0:30:540:30:58

'but, believe it or not, it was once possible to have half a turtle.'

0:30:580:31:02

There are fossil turtles going back to about 240 million years,

0:31:020:31:08

and I think the earlier ones got the plastron first.

0:31:080:31:10

-Yes, they did.

-Which implies to me that they were protecting

0:31:100:31:13

against something coming up and biting them from beneath.

0:31:130:31:16

The plastron was developed because they used to have predators

0:31:160:31:20

that used to come up underneath them in the water,

0:31:200:31:22

and on the top of them they just had

0:31:220:31:24

a backbone with a little bit of a shell, but not a complete covering.

0:31:240:31:27

-Well, shall we open her up and have a look inside?

-Yes.

0:31:270:31:32

The turtle's shell is a good adaptation for surviving predators,

0:31:330:31:39

but how did turtles survive through the KT?

0:31:390:31:42

-This has quite an impressive intestine.

-They have.

0:31:420:31:45

Wrapped round like a rather unappetising sausage.

0:31:450:31:48

Part of the answer lies with its lungs.

0:31:500:31:53

But to get to them I need a stomach almost as strong as the turtle's.

0:31:550:32:00

-Certainly a lot of bowel involved here.

-Yes.

0:32:000:32:03

And we've arrived at a position where we can see the lungs.

0:32:050:32:09

Yes, there's a very large surface area for these lungs.

0:32:090:32:13

The benefit of their lungs

0:32:130:32:15

is that these animals can stay submerged up to five hours,

0:32:150:32:19

but the benefit is they can take in air that can go through

0:32:190:32:22

into their lungs and out into their blood and out into the muscle.

0:32:220:32:26

So therefore that's why they can stay submerged for such a length of time.

0:32:260:32:30

So they really are diving champions.

0:32:300:32:32

Not only can turtles break records for staying submerged,

0:32:350:32:39

they can also win awards for surviving without food.

0:32:390:32:42

This one has been floating so long it even has barnacles.

0:32:440:32:47

This was brought in and actually has floater's disease.

0:32:480:32:52

As you can see, it's got air under the shell here,

0:32:520:32:56

and that's caused it to float on this side.

0:32:560:32:59

We've actually had animals brought in here that have been found

0:32:590:33:02

and they have probably been floating for about 12 months without eating.

0:33:020:33:06

Because once they float, they get this floater's disease

0:33:060:33:09

and they get air under their shell

0:33:090:33:11

and they can't dive down to actually feed.

0:33:110:33:13

So they've been floating.

0:33:130:33:16

Up to 12 months they can float and they can live on their fat stores.

0:33:160:33:20

So, like crocs and snakes,

0:33:200:33:22

the turtle is capable of not eating for a very long time.

0:33:220:33:26

This little turtle, has it got a name yet?

0:33:270:33:29

Well, Richard, it looks like a lovely turtle to me.

0:33:290:33:32

It looks like a pure gentleman, so therefore it should be Richard.

0:33:320:33:36

Well, I'm exceedingly flattered

0:33:370:33:39

to have an ancient living fossil named in my honour.

0:33:390:33:44

Thank you very much. I'm delighted.

0:33:440:33:46

After more than 200 million years of survival,

0:33:500:33:56

today, turtles are seriously endangered.

0:33:560:33:58

This time by man.

0:33:580:34:01

Humans are destroying turtle habitats

0:34:010:34:04

and spawning grounds in a way even the KT could not.

0:34:040:34:08

The turtle's armour can protect it from a hostile world.

0:34:120:34:15

But an even more effective strategy is to use a shell

0:34:170:34:20

to create a private and protected place.

0:34:200:34:22

Shells allowed ocean-dwelling invertebrates

0:34:240:34:27

to create their own microhabitats.

0:34:270:34:30

The earliest shelled molluscs

0:34:320:34:34

evolved more than 400 million years ago.

0:34:340:34:37

They survived the KT and continue to grow in abundance

0:34:390:34:43

here in Delaware Bay,

0:34:430:34:44

clinging to the rocks and ruins on the shoreline.

0:34:440:34:47

They may have survived the KT,

0:34:510:34:53

but they are easy pickings for certain two-legged mammals.

0:34:530:34:56

Actually rather good.

0:35:030:35:05

Another way to survive a crisis is...

0:35:050:35:08

..to clam up.

0:35:100:35:11

A lot of molluscs came through

0:35:170:35:19

because of their ability to seal themselves away from trouble.

0:35:190:35:23

Mmm!

0:35:240:35:25

Fairly yummy.

0:35:270:35:28

Probably the most delicious of these survivors, the oyster.

0:35:300:35:34

Which lives attached to rocks.

0:35:410:35:44

Securely fastened to rocks, often in the inter-tidal area.

0:35:450:35:50

Mmm! Yum!

0:35:520:35:53

I'm eating it washed down by another survivor,

0:35:560:35:59

beer from the oldest brewery in America.

0:35:590:36:02

Oysters suck in water, filter and consume its nutrients

0:36:050:36:09

and expel it again.

0:36:090:36:11

Since some oyster species can pass more than five litres

0:36:110:36:15

in a single hour, they would, in their own small way,

0:36:150:36:18

and over thousands of years,

0:36:180:36:20

contribute to the spring-cleaning of the seas after the crisis.

0:36:200:36:24

Living in well-stirred inter-tidal waters, oysters were protected

0:36:330:36:37

from the de-oxygenation event that poisoned so much marine life.

0:36:370:36:42

They still prosper today at the edges of the sea,

0:36:420:36:45

and they have provided man with an accessible foodstuff,

0:36:450:36:49

easily prised off rocks with primitive tools

0:36:490:36:52

since the early days of our species.

0:36:520:36:54

The nautilus is another shelled Cretaceous survivor.

0:37:040:37:09

It couldn't shut the world out completely,

0:37:100:37:12

but then, as a scavenger, it didn't want to.

0:37:120:37:15

The nautilus is a cephalopod, a relative of the squid

0:37:190:37:24

that can live to be 20 years old.

0:37:240:37:27

It uses a kind of jet propulsion to navigate itself through the depths.

0:37:290:37:33

The nautilus's big eyes are misleading.

0:37:350:37:38

In fact, it has poor vision and relies on its sense of smell

0:37:380:37:43

to forage for food and locate potential mates.

0:37:430:37:47

Perhaps smell would have been a handy survival trait

0:37:490:37:52

when the sun had been blotted out

0:37:520:37:54

and the oceans had been plunged into darkness.

0:37:540:37:58

But it probably wasn't this that saved it.

0:38:000:38:03

Once again, reproduction could have been the real key.

0:38:030:38:07

This is one of the first fossils I ever found.

0:38:110:38:15

Since their appearance about 400 million years ago, ammonites

0:38:150:38:19

evolved into thousands of different species of every shape and size.

0:38:190:38:23

And survived everything a hostile world could throw at them

0:38:230:38:28

for more than 300 million years.

0:38:280:38:31

Sadly, it was not these wonderful, rapidly evolving cephalopods

0:38:330:38:38

that made it through the KT, but...

0:38:380:38:40

..the more humble nautilus.

0:38:430:38:45

Some scientists even speculate that the ammonite spawned just once

0:38:470:38:51

at the end of their lives while our friend the nautilus, a superficially

0:38:510:38:55

similar creature, bred several times in a lifetime and made it through.

0:38:550:39:01

The nautilus lays comparatively few large eggs,

0:39:010:39:05

well supplied with nutrients, useful at a time of shortage.

0:39:050:39:10

The collapse of the aquatic food chain,

0:39:130:39:16

just like the collapse of the terrestrial food chain,

0:39:160:39:19

was a good time to be a scavenger or a bottom feeder.

0:39:190:39:21

Even dead species sinking into the depths provided

0:39:250:39:29

nourishment for perhaps the most famous living fossil of them all.

0:39:290:39:33

The coelacanth is glimpsed only rarely and spends

0:39:430:39:47

most of the time tucked out of the way in a safe corner of the ocean.

0:39:470:39:52

This is the only footage of it ever shot by the BBC.

0:39:520:39:56

Was it luck or its special adaptations that allowed

0:39:580:40:03

this living relic to pass through the KT?

0:40:030:40:05

It's tempting to look at its leisurely lifestyle,

0:40:070:40:09

large eggs and habitat as a kind of passport to survival.

0:40:090:40:14

But the answer may be that not only did it have

0:40:140:40:18

ample food to scavenge, it also made an unappetising meal itself.

0:40:180:40:22

Indeed, the coelacanth's oily innards reputedly make it

0:40:220:40:26

one of the most foul-tasting creatures ever to swim the seas.

0:40:260:40:30

Making yourself nasty-tasting and inedible was a tactic

0:40:320:40:36

that was also being employed back on the land.

0:40:360:40:39

One of the most successful plant survivors

0:40:410:40:45

of the last 360 million years, ferns.

0:40:450:40:48

Ferns are the first to colonise devastated landscapes.

0:40:480:40:54

They lack both flowers and seeds,

0:40:540:40:57

reproducing by spores carried on the underside of the leaves.

0:40:570:41:02

And they release them in their millions.

0:41:020:41:06

This is a male fern, a very elegant fern.

0:41:060:41:10

And here, look, on the back of the leaves,

0:41:100:41:13

are these little spore capsules

0:41:130:41:16

which ensure their wide distribution and they're toxic.

0:41:160:41:21

Few animals can eat them

0:41:210:41:22

and today there are an incredible 12,000 species.

0:41:220:41:27

The KT extinction event triggered what's called the fern spike,

0:41:330:41:36

the sudden and widespread appearance in the fossil record

0:41:360:41:40

of billions of spores derived from these ancient plants.

0:41:400:41:44

The aftermath of the asteroid impact had been a disaster for many.

0:41:470:41:52

But for others, it was the opportunity finally to shine.

0:41:520:41:56

For the dinosaurs, big had been beautiful,

0:41:580:42:02

and they had conquered almost every ecological niche available...

0:42:020:42:07

except one.

0:42:070:42:10

Burrowing underground were tiny mammals, like these shrews.

0:42:120:42:16

Small and delicate, with high metabolism,

0:42:170:42:20

short lifespans and vulnerable young,

0:42:200:42:23

they were, in many ways, the most unlikely survivors of all.

0:42:230:42:28

But when fiery disaster struck,

0:42:320:42:33

they were tucked away safe and sound.

0:42:330:42:36

Our oldest mammalian ancestors were rather inconspicuous little insect eaters,

0:42:430:42:48

something like shrews, and their distant descendants...

0:42:480:42:52

..this little chap.

0:42:530:42:55

A common hedgehog.

0:42:550:42:56

They were excellent at sniffing out food.

0:42:560:42:59

Maybe the ancient mammals could seek out their fellow survivors,

0:43:010:43:06

insects, from the safety of burrows,

0:43:060:43:09

while so many large animals above ground died in the mayhem of the KT.

0:43:090:43:16

If they could find enough food to sustain their warm-blooded metabolism,

0:43:170:43:21

they could endure through hard times.

0:43:210:43:25

Couldn't they?

0:43:250:43:27

The meek were to inherit the Earth.

0:43:300:43:33

After the dinosaurs died out,

0:43:360:43:38

there was an ecological vacuum which was quickly filled by the mammals.

0:43:380:43:44

The small mammals could come out of their underground burrows

0:43:440:43:47

or out of the leaf litter,

0:43:470:43:50

and soon they evolved into forms

0:43:500:43:52

that replaced the dinosaurs that had preceded them.

0:43:520:43:55

Giant herbivores, even carnivores, appeared in a short order.

0:43:550:44:00

But while new species were quickly evolving

0:44:130:44:16

to exploit the opportunities a changed world provided,

0:44:160:44:19

in one sheltered corner of the world,

0:44:190:44:22

some of the very oldest mammals had already claimed their place in the new world order.

0:44:220:44:29

It's a place they still occupy.

0:44:290:44:31

They're KT survivors that belong to a group of early mammals

0:44:350:44:39

even older than the marsupials,

0:44:390:44:40

and who still retain features inherited from their reptile ancestors.

0:44:400:44:45

They are called the monotremes.

0:44:470:44:49

Duckbilled, beaver-tailed, otter-footed, seal-bodied,

0:44:510:44:55

it's no wonder 18th-century naturalists thought the platypus to be a mythical chimera,

0:44:550:45:01

a creature stitched together by unscrupulous taxidermists that couldn't possibly be real.

0:45:010:45:07

But now, I'm off to find one.

0:45:070:45:09

So this is my third time in Warrawong,

0:45:100:45:14

and I haven't yet seen a platypus.

0:45:140:45:17

Oh, right! Hope today's the day.

0:45:170:45:18

So we must very careful in describing them as in any sense primitive,

0:45:180:45:23

because in a way, they're exquisitely adapted.

0:45:230:45:27

They are, definitely.

0:45:270:45:28

Over 100 million years these animals have been around, and they're great at hiding,

0:45:280:45:32

so that's one of the reasons you haven't seen 'em yet.

0:45:320:45:35

So... Yes, I'm sure!

0:45:350:45:37

The habitat here in the Warrawong nature sanctuary is much as it is in the wild,

0:45:390:45:44

which is ideal for the privacy-loving platypus.

0:45:440:45:47

So do you have, what? Two or three, half a dozen here?

0:45:490:45:52

I'd like to think we have about ten.

0:45:520:45:54

We should be quiet now, because you never know,

0:45:550:45:59

this might be the time to actually see the platypus.

0:45:590:46:02

(I can see some ripples down there.)

0:46:380:46:41

(Perhaps we should move along a bit.)

0:46:470:46:49

'The platypus loves this sort of habitat,

0:46:530:46:57

'but as the hours tick by, it becomes increasingly clear

0:46:570:47:00

'we're about as welcome as paparazzi on a private beach.'

0:47:000:47:04

It's very discreet, you have to say.

0:47:100:47:13

Well, I mean, it would be great if we could see one.

0:47:180:47:21

Could that be one?

0:47:300:47:31

Every time I think I've seen one, another bird hops into view.

0:47:350:47:40

-They're not frightened of the lights.

-No, not at all.

0:47:400:47:43

Our platypuses have been conditioned to have light on them,

0:47:430:47:46

and they're not too fussed.

0:47:460:47:48

Then, finally, after 18 years and nearly five hours,

0:47:490:47:54

I see the platypus.

0:47:540:47:56

(There we go!)

0:47:580:47:59

There it is again.

0:48:010:48:03

They lay their eggs in burrows, don't they?

0:48:100:48:13

-They do, yeah.

-So how many in this pond?

0:48:130:48:15

I think there's about three burrows in this pond, and they're very extensive burrows.

0:48:150:48:20

So when the female lays her eggs,

0:48:200:48:22

she lays up to two or three eggs in the burrow,

0:48:220:48:26

and they could be in the burrow for four to five months, developing.

0:48:260:48:30

They take about 12 days to hatch,

0:48:300:48:32

and she incubates the eggs.

0:48:320:48:35

Gosh, that's a clear view.

0:48:360:48:38

That's as good as you ever get.

0:48:380:48:40

'As well as being an egg layer, the platypus also retained something

0:48:400:48:44

'of the cold-bloodedness of its reptilian ancestors,

0:48:440:48:47

'having an average body temperature five degrees centigrade colder than placental mammals.'

0:48:470:48:53

I gather the platypus can be, if you don't handle it right,

0:48:530:48:56

quite a dangerous animal.

0:48:560:48:58

They can, definitely.

0:48:580:48:59

Platypus have a venomous spear on their back ankles,

0:48:590:49:02

and that's just for the males.

0:49:020:49:04

They use that venomous spear against their natural enemy, which are water rats,

0:49:040:49:08

and also against each other during the mating season.

0:49:080:49:11

-I believe the venom is bad enough to kill a small dog?

-It is.

0:49:110:49:14

It caused excruciating pain to the European settlers when they first came,

0:49:140:49:18

and picked these innocent-looking creatures up and got a nasty shock.

0:49:180:49:21

So yet another Australian creature that causes you pain

0:49:210:49:25

-if you don't do it right.

-That's right, we've got lots of them in Australia!

0:49:250:49:29

I came here first 18 years ago.

0:49:310:49:34

I don't need to hunt the platypus now,

0:49:340:49:36

I've seen one of the great survivors.

0:49:360:49:39

The platypus might not be an obvious survivor,

0:49:430:49:47

but its ancestors, swimming, burrowing creatures that rely on smell and survive on insects,

0:49:470:49:52

were adapted to the kinds of conditions the KT crisis caused.

0:49:520:49:57

Evidence suggests the platypus's earliest ancestors may have been around even longer

0:49:580:50:03

than the oldest placental and marsupial mammals.

0:50:030:50:08

The platypus's closest living relative is my final KT survivor.

0:50:080:50:14

'It's an extraordinary creature called an echidna.'

0:50:160:50:19

That way, I'd say, wouldn't you?

0:50:190:50:22

'And it possesses a quality that would become key to mammals inheriting the Earth.'

0:50:220:50:27

Now, where I could hear her earlier was down through there.

0:50:290:50:33

The signal's not any stronger, because you see the little hill...

0:50:350:50:38

'My guide is Dr Peggy Rismiller,

0:50:380:50:41

'a woman who has spent much of her life protecting echidnas and their habitat.'

0:50:410:50:45

She could be... A-ha.

0:50:470:50:49

'Echidnas bear a close physical resemblance to giant hedgehogs,

0:50:500:50:54

'but they're not closely related.'

0:50:540:50:55

So yeah, they're very good at hiding.

0:51:010:51:04

I think she's burrowed at the back of the tree here.

0:51:070:51:11

There she goes.

0:51:140:51:16

This is Big Mama. I've known her for 23 years.

0:51:160:51:18

So it's a waiting game. I just wait for her to relax.

0:51:210:51:25

She has the advantage of being extremely strong.

0:51:250:51:28

And you always go with the spines, so in this direction,

0:51:280:51:32

I'm going with the spines, and see, I'm actually...

0:51:320:51:35

-Do you want that closer?

-That's OK. Just a second, I'll get her out.

0:51:350:51:39

OK.

0:51:390:51:40

It's like digging up great spiny wheat.

0:51:400:51:45

There, you see her face?

0:51:450:51:47

That's her little nose sticking out there.

0:51:470:51:49

You're very lucky to see her face.

0:51:540:51:56

Very often the first thing they do is hide that beak

0:51:560:51:59

because it's the most vulnerable part of the body.

0:51:590:52:02

-How old?

-I think probably about 45.

0:52:020:52:04

45 years?

0:52:040:52:06

That's a human lifetime!

0:52:060:52:08

There you go. Have you held an echidna?

0:52:090:52:12

I'm about to.

0:52:120:52:14

OK.

0:52:160:52:17

She's five kilos, remember. You got her?

0:52:170:52:19

I've got her.

0:52:190:52:21

There she is.

0:52:210:52:22

She's tucked her face well inside,

0:52:220:52:26

so the sensitive nose, or beak, I suppose, is protected.

0:52:260:52:31

But you can see the long claws on either side,

0:52:310:52:34

which make such an effective digging instrument,

0:52:340:52:38

and make them so good at hiding, too.

0:52:380:52:40

Echidnas are the only mammal who can dig straight down into the ground,

0:52:400:52:44

because the front feet go in one direction, the hind feet go

0:52:440:52:47

in the other direction, so they can go straight down and make a hole like she just came out of.

0:52:470:52:52

She's sort of bunching up her spines

0:52:520:52:55

to give her maximum pincushion effect.

0:52:550:52:58

THEY CHUCKLE

0:52:580:52:59

'Like other early mammals, the echidna eats insects

0:53:010:53:05

'and other small creatures.

0:53:050:53:06

'So the survival of these tiny animals helped

0:53:060:53:11

'ensure its survival, in turn.

0:53:110:53:13

'The echidna has been using its sensitive beak

0:53:130:53:16

'to ferret out tiny prey for millions of years.'

0:53:160:53:20

Now this little delicate structure is what?

0:53:220:53:26

The lower jaw.

0:53:260:53:27

A pair of struts, really, no more than that.

0:53:270:53:30

Or something like a tuning rod,

0:53:300:53:32

because when the echidna is foraging, it will put its beak on the ground,

0:53:320:53:36

and they're very sensitive to vibrations, so these tuning rods

0:53:360:53:40

can help it actually sense any vibration in the soil,

0:53:400:53:44

which means finding their food source.

0:53:440:53:46

Why do you think echidnas are great survivors?

0:53:460:53:50

I think the first thing to look at is food source.

0:53:500:53:53

If you're going to be a survivor, what do you eat?

0:53:530:53:56

Invertebrates.

0:53:560:53:58

So being an invertebrate eater makes them a good survivor.

0:53:580:54:01

We know invertebrates carried through the crisis at the end of the Cretaceous, yes.

0:54:010:54:06

And what's going to be around longer than anything else? Invertebrates.

0:54:060:54:10

Secondly, echidnas have a low operative body temperature,

0:54:100:54:13

which gives them an advantage.

0:54:130:54:14

They also regulate their body temperature, in that when they go to sleep,

0:54:140:54:18

they just let the body temperature go down, which means they save a lot of energy.

0:54:180:54:22

There she is again. Look at that face!

0:54:220:54:26

'Two vital traits shared by a number of our survivors.

0:54:260:54:29

'An unfussy diet, and a slow metabolism.'

0:54:290:54:32

They are also capable of hunkering down,

0:54:330:54:36

of digging down and hiding from trouble.

0:54:360:54:40

It's not only that, they're good at surviving natural things like fire,

0:54:400:54:44

so because of their digging capabilities

0:54:440:54:46

and being able to lower their body temperature and their metabolism

0:54:460:54:50

during a fire situation which happens in Australia naturally,

0:54:500:54:53

these guys are going to survive.

0:54:530:54:55

Hiding away - another common survival technique.

0:54:560:55:00

But unlike our reptile survivors,

0:55:020:55:04

that produce many, well-developed offspring,

0:55:040:55:07

the echidna lays a single egg, which hatches in her pouch

0:55:070:55:11

and grows into an underdeveloped and hairless baby, called a puggle.

0:55:110:55:17

The reproduction is quite slow. They're eight years old before they're sexually mature,

0:55:230:55:27

they may only have one young every three years.

0:55:270:55:30

And the puggle gets its own additional security,

0:55:300:55:34

a nursery burrow.

0:55:340:55:35

The amazing thing about the echidna,

0:55:350:55:38

very different again from any other mammal -

0:55:380:55:41

once the puggle is in the burrow, its life changes dramatically.

0:55:410:55:46

When it was in the pouch, it could suckle at any time,

0:55:460:55:49

-because they do suckle milk.

-Yes.

0:55:490:55:51

Once it's in the burrow,

0:55:510:55:52

mom only comes back for two hours every five days.

0:55:520:55:57

And the other advantage is they have a low temperature,

0:55:570:56:00

the burrow is quite cool,

0:56:000:56:02

so the young echidna is growing at a slow rate.

0:56:020:56:06

But she will continue for seven months.

0:56:060:56:08

So this is really rather slow child-rearing, isn't it?

0:56:080:56:12

Particularly for an animal of that size.

0:56:120:56:15

Investing so much time and energy into one or a few offspring

0:56:200:56:25

is a distinctly mammalian reproduction strategy.

0:56:250:56:29

And nurture may have been key to evolving perhaps what we regard

0:56:290:56:33

as the greatest survival trait of them all.

0:56:330:56:37

Intelligence.

0:56:370:56:39

One thing that strikes me, I think I'm right -

0:56:390:56:42

-it seems to have a rather large brain.

-Good observation.

0:56:420:56:45

Actually, the brain is huge for the size of the animal.

0:56:450:56:48

And I think the most important part is the neocortex.

0:56:480:56:51

Have you ever heard of the neocortex?

0:56:510:56:54

Explain what it does.

0:56:540:56:55

Well, the neocortex is the frontal part of the brain,

0:56:550:56:58

where your memory, your reasoning, your personality comes from.

0:56:580:57:03

And echidnas have great personalities.

0:57:030:57:05

But I think the best reason I heard for the neocortex

0:57:050:57:08

was from a ten-year-old student, who said,

0:57:080:57:11

"You said they were around with the dinosaurs, so they have a lot to remember."

0:57:110:57:15

-That's rather a good answer!

-Absolutely!

0:57:150:57:18

Big brains would prove to be key in the evolution

0:57:220:57:26

and success of mammals.

0:57:260:57:27

Today, mammals have occupied every ecological niche

0:57:300:57:33

once inhabited by dinosaurs.

0:57:330:57:36

Yet it still seems extraordinary that small insectivores

0:57:360:57:41

could produce giant predators and potbellied grazers.

0:57:410:57:44

It seems nature abhors a vacuum,

0:57:440:57:47

and every vacant ecological niche is an opportunity waiting to be filled.

0:57:470:57:54

'But few prehistoric bookies would have put money on mammals

0:58:000:58:05

'winning the lottery of life.

0:58:050:58:07

'Which, I suppose, just goes to show...'

0:58:070:58:10

Sometimes, to be a survivor,

0:58:100:58:12

it does no harm to have luck on your side.

0:58:120:58:16

-# The winner takes it all

-Takes it all

0:58:160:58:20

-# The loser has to fall

-Has to fall

0:58:200:58:23

-# It's simple and it's plain

-Yes, it's plain

0:58:230:58:27

# The winner takes it all... #

0:58:270:58:30

In the next episode, I go in search of survivors from the Ice Age.

0:58:320:58:38

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0:58:410:58:44

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