How to Build a Dinosaur Page #4

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LOW GROWL:

Palaeontologists now have access to

an incredible set of clues

that can help us understand the posture

and movement of dinosaurs.

It's a set of clues that can tell us what they

might have looked like in the flesh,

a set of clues that can even shed light

on how quickly they might have run,

and a set of clues that we all see every day.

Birds are the living descendents of a dinosaur

because dinosaurs have living descendants.

Dinosaurs are not extinct

they did not become extinct at the end

of the Mesozoic era.

'It's an incredible idea

'but most experts now believe that today's birds

'are the direct descendents of ancient dinosaurs.'

- So, does that mean birds actually ARE dinosaurs?

- Yes, absolutely.

How can you be sure about that?

You have evidence from the skeletal anatomy,

you have evidence from the shape of the eggs

and the microstructure of the eggshell,

a discovery of a wealth of feathered dinosaurs,

animals that are unquestionably dinosaurs

and yet have feathers that look just like

the feathers of modern birds.

'It's a discovery that revolutionises

the way we see dinosaurs.'

Even some tyrannosaurs were feathered,

but the relationship between birds and dinosaurs

can tell us much more than simply

what they may have looked like.

So, does this mean that we can use living birds

to help us understand dinosaurs?

Absolutely.

You know, you have 10,000 living species of birds

that are providing you an enormous

amount of information

that you can use to understand the biology

of the ancient dinosaurs.

It's quite amazing, but it also makes

a certain degree of sense

when you really look at them.

If we want to learn about how

the ancient dinosaurs moved,

and even how quickly they ran,

few animals can tell us more than ostriches.

They evolved on an early branch

of the avian family tree,

and like the dinosaurs they're related to,

they're large, bipedal and flightless.

- We have some living dinosaurs here to take a look at.

- Yeah, a whole field of them.

Hello, ladies.

- They're all ladies, are they?

- Yes.

Yes, they're a bit more manageable

when they're females.

'Dr John Hutchinson is based at

the Royal Veterinary College just outside London.

'He's one of the world's leading experts

on dinosaur movement

'and Luis has been consulting him

'to make sure his T rexs reflect the latest theories.'

- Can I touch them?

- Yeah, yeah, yeah.

- Yeah? Will they peck me?

- They'll peck at your rings.

- Will they?

- Don't peck at my rings.

- They'll try to take them off.

- But they're not very strong at pecking.

- No.

SHE LAUGHS:

I want to feel your feathers.

Now, this might be what a dinosaur felt like to touch.

- That's really soft and lovely.

- Yeah, just like a cuddly toy.

Aww!

- I'm stroking dinosaurs.

- Dinosaur.

- Yeah.

Get off me.

They do look like dinosaurs, especially

when you know some dinosaurs were feathered.

They do, and those feathers are quite

primitive in their structure,

a lot like some of the fossil feathers we find.

'The similarities aren't just on the surface.

'We can get a much better understanding

of ancient dinosaurs

'by looking at the anatomy of

their modern relatives in depth.

'And a local farm has recently had to

put down one of its ostriches.

'As an anatomist, I'm very used to

dissecting cadavers.'

Now, I don't usually wear Wellington boots

when I'm dissecting, I have to say.

'But this will be the first time that I've ever

dissected a bird

'or, for that matter, the descendant of a dinosaur.'

So, John,

talk me through the anatomy that

we can see on the surface.

That's our heel, the ankle joint,

but birds walk with that clear of the ground,

just like their dinosaurian ancestors did.

And really just two toes, and one main one.

The middle toe is their dominant toe,

just like in a dinosaur,

the third toe is the major toe of the foot.

'And there are other similarities to

their ancient relatives.'

I don't know if you can see this,

but here's the tip of the wing right here

- and there's a...

- Oh, there's a claw.

- ..lovely little claw coming off it.

- Yeah.

- So...

- That's at the end of one of the digits

- on their arms, on their wings?

- Yep.

- And it's just there as a relic of their ancestors.

- Mm, yeah.

'The real clues about dinosaurs

'come from seeing what the relationship is

'between a bird's muscles and it's bones.'

Right away we can see some of

the thigh muscles here.

- You can see this lovely...

- Yeah, I can see these.

- ..red colour,

beautiful beefy muscle.

So, based on dissections like this,

how accurately do you think

you can reconstruct the musculature

of extinct dinosaurs?

You can look at any bone and tell something about

the soft tissue anatomy of the animal,

from the scars,

the muscle scars and ligament and

tendon scars on the bones,

that are attachment points for all these things

that we see here as soft tissue.

Actually, if I bring a bone over,

we can superimpose these two.

It's got one big muscle attachment right here,

- and dinosaurs have a muscle scar just like this.

- Do they?

- It appears in the first bipedal dinosaurs,

this scar on the outside of the fibula... - Yeah.

..and is not present in earlier animals.

So, this is another link between dinosaurs and birds.

- So, the next time I see a bipedal dinosaur,

I must look for this lump.

- T rex will have a huge one of those.

- Yeah.

- It's just a massive scar, like this big.

- Yeah.

By estimating the muscle sizes of extinct animals

and inputting them into computer models,

John is able to get an incredible new insight

into how dinosaurs actually moved.

It's basically running a simulation.

The computer's figuring out what is the best way

to use these muscles,

given what we've put in, to raise the body up.

We're not animating it, we're not saying,

"Do it this way".

We're just giving it some basic rules of biology,

this is what kinds of things you should

be trying to do overall,

- and then it finds the best solution.

- Yeah, yeah.

So, John, you've actually done work

trying to reconstruct how T rex would have looked,

how his muscles would have worked,

how he would have run.

What kind of results have you got from that?

Yeah, we've found, using our computer models,

that a human sprinter

which can do 25 miles an hour or a little faster

would probably be pretty well matched for

a muscular tyrannosaurus,

or an average human who can run about

would probably be a pretty good match for

a skinnier version of a T rex.

John, I've heard some theories

where T rex has been put forward as running very fast,

probably faster than that.

So, has your work basically disproved that?

Yeah, I think it's put a lot of doubt in that idea,

that T rex could run as fast as a racehorse,

or even faster,

so 40 miles an hour, something like that.

I don't think you'd need an automobile to outrun a T rex.

We'd have a chance of outrunning them?

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