Attenborough and the Sea Dragon Page #5

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the remains of skin on

such an ancient fossil.

But this microscope can

also magnify its structure

tens of thousands of times.

Here, we have an exceptional level

of preservation of the skin

of our ichthyosaur, despite

being 200 million years old,

so the structures we're looking at here

are around half a micrometre across

and a micrometre is one

millionth of a metre

and you see here these little granules

and these are preserved melanosomes.

Now, melanosomes contain the pigment

that you have in mammal hair,

in bird feathers and in reptile

skin and the abundance of them

and the distribution of them can tell us

about the overall colour

patterns of the animal.

So, having a high abundance means

you're likely to be darker

and having a low abundance means

you're likely to be lighter.

This area has come from the back.

There's a large abundance

of these melanosomes.

There's a lot of pigment here

and when we look at samples

that have come from the

bottom of the animal,

we don't see this pigment

in this level of abundance

so it most likely had a much

darker back than it did a belly

and this conforms to a

type of colour pattern

known as countershading in modern animals.

You can see countershading in

lots of sea animals today.

Great white sharks, for example.

Both predators and prey

are coloured in this way.

It makes them more difficult to

see both from above and below.

So, this is the first time

that we've actually seen

evidence of a countershaded

pattern in an ichthyosaur.

So, that really is a step

forward in our knowledge.

It is and it can tell us

a huge amount about the way

the animal might have lived.

Just from looking at that picture?

- Just from looking at these melanosomes.

- Great!

Today, countershaded animals

tend to live in open water

where there's good visibility.

Ichthyosaurs also lived in the open seas

so being camouflaged in this way

would have been very valuable to them.

The latest scientific research

suggests that countershading

might also protect against

ultraviolet light

and even help to regulate body temperature.

As an air-breathing creature,

our ichthyosaur would have had to

spend much time near the surface.

So countershading could have been a

benefit for that reason as well.

There are, of course,

many marine reptiles still living

in the oceans today, like turtles.

The biggest of them is the leatherback,

whose ancestors, in fact, were around

at the same time as the ichthyosaurs.

Today, they come ashore

to nest in many places,

including the Caribbean.

This huge leatherback

turtle is laying her eggs.

She's hauled her way up

from the sea and dug a hole

and now she's depositing about 100 of them.

She'll then fill in the hole

and then work her way down back to the sea.

It's clearly a very laborious process.

And that's the challenge facing all

reptiles that live in the sea...

having to come onto land to lay eggs.

Ichthyosaurs were reptiles

and they lived in the sea,

but they were so well

adapted to a life at sea,

that they gave birth to live young

and that would have saved the sea dragons

making the dangerous journey onto land.

There is remarkable evidence

that ichthyosaurs gave birth

to live young in the Stuttgart museum.

And here is a truly extraordinary,

beautiful, almost poignant fossil...

proof positive that ichthyosaurs

gave birth to live young.

Here is the baby, just at the moment

that it's leaving the birth canal.

It comes out tail first and

as soon as it was freed,

it would have risen to the surface

to take its first breath.

But something happened before that did

and here is the proof.

Whatever it was, death

must have been instant.

So, ichthyosaurs gave birth to live babies,

just as many sharks do today.

After several weeks of research,

the team at Bristol University have managed

to reconstruct the skull

of the temnodontosaurus

so that they can analyse

the power of its jaws.

How do you assess the strength

of this animal's bite?

Well, the first thing that we need to know

is the volume of muscle that could

fit into the back of the skull.

So the muscles are attaching round here

and also there's a group of muscles

that are attaching further forward here

and if we know how much

muscle volume there is,

we can estimate how much force

that muscle can generate.

And what did you discover?

We found out that our upper

estimate of bite force

was around 30,000 Newtons and to

put that in a modern day context,

that's twice as powerful as the

largest saltwater crocodile

- that's been measured.

- Twice as powerful?

- Yeah.

- So that's enormous, yeah.

- Yeah, it's a very powerful bite force.

So, this must have been the animal

with the most powerful bite

of its time, mustn't it?

That's absolutely right, yeah.

Of its time, it would have been.

Not only did it have a powerful bite,

its jaw-closing muscles also attach

quite close to the jaw joint.

Now, normally in animals

where that happens,

they have quite a fast,

but less forceful bite,

but the fact that this

animal is actually so big

means that it has a fast bite,

but also by virtue of its sheer size,

it also has quite a

powerful bite as well, too,

so it basically has the

best of both worlds.

- So, this was the king of the Jurassic sea.

- Or queen!

Sorry!

- Yeah.

- Yeah.

So, it seems fairly likely that

temnodontosaurus was strong enough

not only to kill our sea dragon,

but to rip its head clean off.

It must have been a terrifying battle.

Our investigations have given us

a pretty good idea of how

our sea dragon died.

But can the reconstruction work

carried out at Bristol University

tell us more about its life?

All the blocks containing the

fossil have now been scanned.

With those scans,

the team were able to

separate the individual bones

and then put them back together to create

a 3D image of the ichthyosaur's

body before it was attacked.

They've added a head

based on estimates of other

ichthyosaur species.

That's magnificent.

This is the whole animal

and we estimate that it may have

been up to around 4.5m long.

Is that bigger than most in Lyme?

Yes, this is certainly bigger

than most of the ichthyosaurs

that we see at Lyme Regis.

It looks huge. It looks amazing.

Here are the forelimbs right at the front

and we've got hindlimbs here and at

the back, we've got a tail bend.

This is supported by the backbone,

which extends along the

whole length of the body.

- But that bend is natural, isn't it?

That's not a break. - Yes.

That gives strength to the

lower element of the tail

for driving it forward.

Much like a shark,

the tail bend is the main

propulsive organ of the animal.

So, could this be a new species?

Yes, these pieces of evidence together

suggest that it is going to be a new

species and it's jolly exciting.

- They don't come along every day.

- Historic!

- Yes.

This is wonderful news.

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