The Real T rex with Chris Packham

Tyrannosaurus Rex.

The most terrifying predator that ever stalked the planet.

What an animal.

How powerful this predator must have been.

It's a cultural icon.

The poster boy of the dinosaurs.

But for years, we got it completely wrong.

I fell in love with the dinosaur,

but it didn't look anything like this.

I'm Chris Packham, and it's been my lifelong dream

to meet the real T-Rex.

And now in the golden age of dinosaur science,

I've got my chance.

This is the first time I've been able to

walk in the footsteps of dinosaurs.

With the living world as my guide,

and the latest technological tools,

I'm going to create the most authentic T-Rex ever.

On my journey, I'll test its bone-crushing bite...

When you said pulverised, you weren't joking.

..its top speed...

I'm going to get inside its mind.

..and I'll ask, what did it really look like?

Really, they were bristled.

I'm going to reimagine and rebuild T-Rex.

Oh, love that.

And finally, bring it back to life.

HE GROWLS

As a boy, I was obsessed with dinosaurs.

I'd take them out into the woods around my house to create these

little cameos, these little sort of views into the Cretaceous period in

Cleveland Road in Midanbury.

And there was absolutely no doubt which one was my favourite.

Tyrannosaurus Rex.

The fact that it was big, fierce and most essentially extinct.

And therefore, I couldn't see it and I would never see it,

made it my favourite animal.

And I would wander around the woods around my house,

wondering if that was the sort of place that Tyrannosaurus would live.

You see, to me, this animal was as real

as the grass and the trees.

And some days I'd even convince myself

that Rexie was watching me.

GROWLING

ROARING

But how authentic was the creature that lived in my imagination?

My T-Rex was a product of the imagery

that I absorbed from the movies and books of the age.

But since then,

there's been a radical revolution in our understanding of its appearance

and its behaviour.

As it turns out, early scientists

and popular culture had it all wrong.

As a child, I'd fallen in love with a fantasy.

So now, I'm going to put that right.

I'm on a mission to find the real T-Rex.

MUSIC: T-Rex, 20th Century Boy

In the badlands of north eastern Montana,

the exposed rocks harbour a treasure trove of fossils.

# Everybody says it's just like rock 'n' roll. #

They were laid down 65 million years ago,

when giant dinosaurs roamed the Earth.

Back when a passing meteorite smashed into our planet,

wiping them out for good.

But now these ancient rocks are revealing

the secrets of that lost world,

giving me the chance to realise my childhood ambition.

I've crossed an ocean, come to another continent to see an animal.

I've done that loads of times before, of course.

But this one is going to be really special.

My guide is palaeontologist Doctor Greg Wilson.

-Chris.

-Greg.

-Good to see you.

-Good to see you.

He's meeting me in the infamous Hell Creek...

..the Mecca for T-Rex hunters.

These rocks are filled with fossilised bones

from the period of the Earth's history known as the Cretaceous.

Back then, this was a subtropical flood plain teeming with herds of

majestic plant-eaters.

And like the wildebeest of the African Savannah,

where there is prey,

there are predators who stalk them,

the king of the dinosaurs.

Tyrannosaurus Rex.

We're here in front of a block of this T-Rex specimen

that has parts of the back of the lower right jaw.

So this is the articulating surface with the skull.

-OK.

-And so this, from here to here,

is about the back third of that lower jaw.

Do you have the material with the teeth?

We do. We've collected that already.

That appeared right over here in this space

and we collected that last year.

This is a big day.

Actually it's a very, very big day.

It's taken me 50 years to get from Southampton to Montana

to finally meet a T-Rex.

Not only meet it, but actually reach out and touch it.

Oh, I can't tell you.

Now I know it's a fossil, I know it's not a real bone,

it's the mineralised remains,

but you've got to allow for

a little bit of romance in science occasionally.

And that's our mission here.

We've got to try and make T-Rex real.

And I can reach out and use my finger

to bridge more than 60 million years.

What we've got to do is to use the very best science

to bridge that period of time, too.

To finally produce the real T-Rex.

It's only when you piece these fossilised bones together

that you start to get the full picture.

Here in the Natural History Museum in Berlin,

a new specimen is on display.

Complete skeletons are extraordinarily rare.

Only about 25 good T-Rexes have ever been discovered.

And this one is an absolute beauty.

Four metres high at the hip, over 12 metres head to tail,

and an enormous skull, filled with some of the largest teeth ever seen.

They call him Tristan.

Hello, Tristan.

What an animal.

How impressive, how powerful this predator must've been.

But it's just the bones.

What did it look like?

How fast could it move?

What did it do with those jaws?

I'm going to find the answers on my journey.

And bring the evidence back here to Tristan piece by piece.

Driven by the science, I'm going to put the flesh back on these bones.

And a great place to hunt for the first clues is in modern nature.

In recent years,

the study of living animals has revealed

an enormous amount about the biology,

biomechanics and the behaviour of the dinosaurs.

Modern animals really can hold the key to the past.

The answers are out there.

And I know exactly where to start.

These Alabama swamp lands are home to some real old-timers.

If we want to find out how T-Rex worked,

to find out how its skull functioned, its teeth functioned,

then we need to practise a bit of comparative anatomy.

And to do that there's only really one place to look.

And that's these guys, the crocodilians.

This is a North American alligator.

It's 13 feet long and it weighs a thousand pounds.

That's more than 450kg, that's half a metric tonne.

This is as close to a living dinosaur as we're going to get.

And it's very impressive.

It's beautiful. Absolutely beautiful.

Crocodilians have prospered for nearly 250 million years.

Their ancient ancestors somehow survived

that deadly meteorite strike.

And their intimate connection with the world of the dinosaurs

is helping palaeobiologist Doctor Greg Erickson answer many questions.

To understand dinosaur palaeobiology,

we need to understand the biology of living animals.

I use, basically, the data from these living animals

as sort of a time machine to go back and try to understand

what animals such as Tyrannosaurus Rex were doing.

Come on.

Greg has been studying the crocodilian jaw

to see what he can learn about the raw power of the T-Rex bite.

His team are past masters at

trapping alligators without harming them,

but this job is, um, not for the faint-hearted.

What have we got, Greg, in terms of equipment here?

Well, I call it dragon slayer. But it's a bite force metre.

So, I'll tell you what, I'm going to go ahead and test the bite.

And Wesley is going to help me.

-Yeah.

-And do you want to do the readings for me?

-I'll do the readings.

-Fantastic.

-Set this down there.

-Ready?

-Yeah.

-Oh, yeah.

What did we get?

2,058 pounds.

Wow, over a tonne of bite force.

2,058 pounds!

My goodness me.

Greg, let's put that in perspective.

If we bite down hard, our molars are producing what in pounds?

About 200 pounds for a human.

And I read that a big domestic dog, a Rottweiler, about 320, 328.

And then a hyena, famed for its bone-crushing qualities,

-1,100.

-Yes.

Nothing's coming close to the alligator.

Yeah, crocodilians are today's bite force kings.

But, you've used these animals to inform reconstructions

of the T-Rex jaw musculature.

And what did you come up with for the T-Rex?

Well, yeah, these are a great model for figuring out the bite forces

of animals like Tyrannosaurus Rex.

They have very similar musculature, and with T-Rex,

we estimate bite forces of 8,000 pounds.

-8,000?

-Yeah.

8,000.

So that's a crushing bite of enormous magnitude.

It's mind-boggling to think about.

That's the equivalent of being sat on by an elephant.

So, let's see it in action.

This is the skull of a cow.

It's the closest we could get to a typical T-Rex prey,

a mighty herbivorous dinosaur.

Greg's using an impact generator to recreate the power of T-Rex's bite.

Greg, I normally like to keep my skulls

in perfect condition in my collection.

But, we're about to bust this one.

Yeah, well, what we have here is a 25 tonne press,

and we've got it set to generate four tonnes.

Just to demonstrate what that kind of force is capable of doing.

550, 600, 1,500.

Wow. Oh, Greg. Oh, dear, oh, dear.

That's T-Rex bite force right there.

-Remove these pieces.

-Look at the carnage.

So, basically that's bone that's endured the bite force of T-Rex.

Basically, this is just dust, isn't it?

-Isn't it amazing?

-Nothing survives the bite of T-Rex, does it?

T-Rex was the ultimate killing machine, in my opinion.

But how did all of this crushing power work with these massive teeth?

After all, T-Rex is famed for its colossal set of deadly daggers.

But Greg shows me that, amazingly, T-Rex's teeth weren't sharp at all.

There's more than meets the eye here, these are magnificent teeth.

These are the largest teeth of any dinosaur,

and they're actually quite blunt.

It's sort of like a railroad spike,

or as some of my colleagues call them, lethal bananas.

And it's kind of what it's shaped like, a banana.

They're very dull on the tip,

but one of the secrets is this animal

has a serration row called a carina

on the front and the back here.

This allowed this animal to basically crack bones,

tear away those pieces and swallow them.

And also to cut through flesh at the same time.

The bones would literally explode when

T-Rex made a very forceful bite.

So, how do Rex's bananas combine with that awesome crushing power?

Greg has made a brass T-Rex tooth to find out.

-Go.

-OK.

Wow. Wow.

T-Rex bites again.

Wow.

Look at that.

Destroyed.

You can see where it initially entered there, Greg.

Yeah. So, it made a hole, didn't it?

Yeah, it's like a hot knife going through butter at first.

But then it basically introduced a crack where this serration edge,

or carina is, and split the bone apart.

And that was those ridged edges, the carina.

Absolutely, that's how it worked.

-And that was, what, how much bite force?

-2,405.

-Yeah.

-That's like a quarter of what it could have been,

or capable of doing.

Yeah, you can imagine,

it could easily have done this to much larger bones.

-Yeah.

-Maybe even bones from you know, a large duckbilled dinosaur,

even triceratops.

-It's amazing, isn't it?

-It's amazing.

T-Rex clearly had a bite like a super crocodilian.

But, how reptilian was the rest of him?

I head back to Tristan in Berlin to find out.

If you inspect his bones,

there are telltale markings that show where his muscles attached.

These allow us to reconstruct his immense musculature.

And as we add the flesh to his bones,

the prominent muscles behind his head are a clue to his true nature.

Look at the way that this white-backed vulture is feeding.

It looks a bit manic, but it's under control.

And look at the way the bird is using its neck,

the powerful muscles on the back of its neck, to pull back.

There, look, you see it now.

It's found something that is quite tough to get at and it is using that

neck, bracing itself all the time with its strong feet,

effectively its hindlimbs.

We know from the fossil evidence

that T-Rex's muscles were constructed

just like those of a carnivorous bird.

So from what we understand from T Rex's physiology,

it's very likely that it would have fed

just like this vulture is feeding now,

so it was a lot more like a bird than crocodilian.

Evidence that dinosaurs are related to birds

has radically changed the study of T-Rex.

But when I was a kid, experts were still in the dark.

Tyrannosaurus, king of the tyrant lizards, 20 feet high,

fiercest creature that ever lived.

Yes, this was the T-Rex I knew as a boy.

Early palaeontologists had decided that it should stand erect.

You see, they'd noted that its skeleton with its large rear legs

and long, tapering tail was a bit like that of a...

kangaroo.

So naturally they decreed that it should stand like one,

and T-Rex stood tall for over half a century,

until they realised they'd got it completely wrong.

I fell in love with a dinosaur,

but I fell in love with the wrong dinosaur,

because it didn't look anything like this.

Today's palaeontologists have made great strides

correcting the errors of the past.

Helped by the fact that bones are not

the only trace left behind by the dinosaurs.

In Dino Valley State Park in Texas,

there lies an extraordinary set of

ancient footprints made by a dinosaur very similar to T-Rex.

Glenn Cooban has spent years tracing its tracks.

About 112 million years ago, this was not a riverbed,

this was an ancient, giant mud flat

and when the tide would go out,

it would expose many miles of moist mud.

When the surface is moist, like after a rain,

it looks like they walked through five minutes ago,

and to me it is the next best thing to being beside

a living, breathing dinosaur.

This trackway contains clues as to how T-Rex would have walked,

so I've joined Glenn for a prehistoric paddle.

That is fantastic.

I mean, look at that.

Do you know what? This is the first time

I've been able to walk in the first steps of dinosaurs,

quite literally in the footsteps.

This is a complete trackway, isn't it?

How many are there in this sequence here?

Well, if that gravel was removed,

130 in a row and then there is a scoured area,

and then 20 some additional tracks

before they disappear under the bank.

The prints are incredibly clear,

but it's the absence of something else that's even more compelling.

There is no tail swipe at all.

No. There is no sign of a tail drag here,

or on any of the other trackways in the park,

so we can be confident they did not drag their tails.

The implications of this are pretty fundamental.

Tyrannosaur-type dinosaurs lifted their tails off the ground.

That means T-Rex didn't stand tall like a kangaroo.

It bent forwards.

Its enormous tail was the counterbalance,

for its giant, heavy head.

It turns out that the king of the dinosaurs stooped to conquer.

But stance is not the only information

we can glean from these trackways.

Footprints reveal much more than dinosaur shoe size.

And using a combination of modern and traditional techniques,

Glenn gives me the full picture.

So, Glenn, here we have got one of the photographs and here it has been

treated with processes of photogrammetry.

What can this tell us when we have done all of the prints together?

Well, it is visually stunning and you can immediately

get an appreciation for the depth of the track

and things like the pads on the foot.

If you try to do a conventional map, and even if you record the outlines

very carefully, you still don't get a good appreciation

for the depth and the contours that you can with a technique like this.

OK, so this is going to give us a lot more information

in terms of the way that this animal was moving.

The data collected helps to inform the construction

of precise 3-D models of the dinosaur's feet.

This is a latex rubber mould that I made,

and you see more detail often in the mould than the actual track.

What's interesting about this one

is that obviously it has put its foot into the mud,

and then rather than drag it along,

-it has pulled it out backwards.

-Pulling it out backwards, yeah.

-That is similar to way birds walk, isn't it?

-Right, right.

From muscles to footprints,

the evidence is stacking up.

Dinosaurs and birds are very closely related.

In fact, scientists have proved that modern birds

evolved directly from small dinosaurs, well,

the lucky few who made it through the mass extinction event.

So, if I want to get a sense of T-Rex's athletic prowess,

I am going to forget about sluggish reptiles.

I am going to turn to flightless birds.

An emu or an ostrich can top 30mph.

So could a sprinting T-Rex reach these kinds of speeds?

In recent decades, blockbuster movies have portrayed T-Rex

as a bit of a Roadrunner,

but there's a real problem with that idea.

Unlike those long-legged birds,

T-Rex is carrying a two tonne tail.

A team from the University of Chile

recently explored the effects of tails on birds.

By carefully strapping what looks like

a modified toilet plunger to a chicken's backside.

This experimental tail

totally transforms the bird's posture and gait.

It begins swinging its legs from the hip rather than the knee.

This shows us how the tailed T-Rex may have walked.

But, of course, the bigger question is, could it run?

One man is on the case.

Professor John Hutchinson combined trackway data with locomotion in

flightless birds to unlock the secrets of T-Rex's biomechanics.

The fossil footprints of a large dinosaur are really useful,

but they only tell us so much,

so we use experiments with living animals like an ostrich.

We can go look at an ostrich, see how an ostrich moves,

apply that information to the fossil record

using computer models to help inform us

about how T-Rex might have moved.

John has told me there's more to T-Rex's tail than meets the eye.

And Tristan's musculature can reveal its secret.

OK, John, so when I am looking at this skeleton,

and we are making those comparisons to contemporary birds,

the one thing that I see that is very different

is this enormous tail out of the back.

Yes, the tail's enormous,

more like a crocodile or a lizard's tail.

And the tail and the thigh are linked by a huge muscle.

That muscle ran from the tail to the thigh bone, to the femur.

So this is a tail-to-muscle,

that helped draw the leg backwards,

and push a T-Rex forward and upwards.

So the tail is intrinsically important

in the locomotion of this enormous animal?

Yes, and that's really cool.

John's work has determined that

T-Rex's tail-leg combo generated incredible thrust.

But with great power comes perilous instability.

Something best illustrated by dressing Tristan for a run.

Let's bring Tristan up to 10mph,

the speed of a jogging human.

No problem at all.

His flexing tail muscles help his legs power along at a steady pace.

But what happens if we push him up to ostrich speed, 30mph?

Well, he's powerfully built, he can just about get there.

But at this speed, he's putting his life into his tiny hands.

His pounding joints are stressed to the limits.

And for an animal of this size, the slightest stumble could prove fatal.

The bigger you are, the harder you fall.

So, a seven tonne T-Rex falling down would hurt itself.

And that would be maybe the end of it.

So, it would be something a T-Rex would try to avoid, actively.

So, forget ostrich speeds.

Tristan could barely have outrun a human.

And this does make sense.

He didn't need speed.

He just needed to be fast enough to catch his prey,

those lumbering herbivores of the Cretaceous flood plains.

So, now I'm getting much more of an understanding

of how this magnificent animal moved through his world.

And we know from living species,

that to be an effective hunter you need much more than just speed.

Predators must outsmart their prey.

They are planners, masters of stealth and killers of precision.

And none of this fits with my childhood Rex's

reputation as a lumbering dullard.

So, have we unfairly underestimated its brainpower?

To find out, one scientist has called in the medics.

Palaeontologist Dr Larry Witmer

has spent his career trying to get inside T-Rex's head.

The latest medical scanning technology enables him

to conduct a virtual dissection.

In the past when we tried to understand T-Rex,

and we were looking at the fossils,

we could learn only so much from the outside.

But with the advent of CT scanning,

it allowed us to peer inside to see what was going on.

I've joined Larry to see what he's discovered.

The scan detects minute differences in the densities of the fossil.

And Larry uses this information

to create a 3-D model of the inside of the skull.

Larry, I love it when you can just rotate this skull like that.

It is an amazing piece of anatomy, but let's delve inside the skull.

Yeah, we can do that.

You can just sort of make the skull transparent, so we can peer inside.

What I've got lit up over here is actually the brain case.

We can see a lovely brain case here.

But the real advantage is when we start to run a slice through it.

The scan is so detailed,

it can register the volume of the skull's interior.

And this allows Larry to produce something utterly extraordinary.

The precise form of T-Rex's brain.

Larry, this is unquestionably brilliant.

Absolutely sensational.

-Honestly.

-Well, trying to peer inside the mind of a dinosaur,

this is the closest we're going to get to it.

And Larry can make the virtual, physical

by using 3-D printing.

And that is the brain of an adult T-Rex.

Right, right. If you compare something like this

to the skull that it came from,

it just seems vanishingly small.

But really for a reptile,

this is maybe two or three times what we might expect

for a reptile that was the body size of T-Rex.

And that's because it's not a reptilian brain.

It's a bird brain.

Bird-brain used to be an insult, now it's actually a compliment.

In recent years we've discovered that the structure of bird brains is

entirely surprising.

Their neurons, their brain cells are actually much smaller and much more

highly densely packed.

So maybe when we look at something like T-Rex,

we have been misjudging its potential cognitive abilities.

The brain scans allow Larry to bring the behaviour of T-Rex to life.

When a lot of people look at T-Rex, what they see is a feeding machine.

When I look at the head of T-Rex, I see a gigantic sensory organ.

I see, really, the senses of a predator.

Larry has identified the brain centres responsible for smell,

sight and hearing.

And he's found that they are super-sized.

The olfactory bulbs are larger than what we see

in, really, other kinds of predatory dinosaurs.

That means it has a remarkably large sense of smell.

So with regards to vision,

we can look at the optic nerves that are bringing information in

from the retina of the eye.

And those optic nerves are really large,

and that suggests to us that there was a really highly developed

sense of vision, that was very important to these animals.

Perhaps the most astonishing discovery

is this tiny pink structure.

One of the things that can give us a view, potentially,

at the agility of an extinct animal like T-Rex, is the inner ear.

And we can see these structures right in here

that are the key to that.

These semi-circular canals actually sense

turning movements of the head in space.

And what that means is that they can coordinate the movement of

their eyes with the turning movements of their head and body.

And the purpose of that is to keep the prey firmly within their sight.

This is incredible.

You see, this gyroscopic stabilisation system

is a remarkable adaptation found in modern predators...

..from birds of prey to cheetahs.

And it's proof that T-Rex was built for the hunt.

It must have been one of the most advanced

and capable predators ever to walk the planet.

And its inner ear is also revealing the secrets.

You can learn what an animal sounds like from what it evolved to hear.

We can get some of that information by looking at the structure of the

inner ear. In particular the hearing organ, or the cochlear duct.

What that suggests in T-Rex is that it actually had a very sensitive

hearing organ, it was especially sensitive to low frequency sounds,

potentially frequencies lower than even most of us can hear.

What we might call infra-sound.

So what does this mean for T-Rex's iconic roar?

The most chilling noises in the natural world today

come from our top predators.

The howl of the wolf.

The roar of the tiger.

But Larry's findings add to the suspicion

amongst scientists that in reality,

T-Rex sounded nothing like them.

If we look at any of the classic dinosaur movies, T-Rex is roaring.

And the reason we probably thought of this as appropriate

is that large carnivores today, most of them are mammals,

and those are sounds that they produce.

But when we think about T-Rex,

this is an animal most closely related to birds and alligators,

and crocodiles. And those animals make very different kinds of sounds.

Professor Julia Clarke studies dinosaur vocalisation.

And at this recording studio in Berlin

she's agreed to help me try to recreate T-Rex's voice.

Julia, I rather perversely like the fact that T-Rex couldn't roar.

I know, it's really, you know, it grabs you and makes you think,

what was this animal really like?

A good place to start is with our old friends,

the birds and the crocodilians.

Many of them communicate with what's known as closed mouth vocalisation.

So we're going to kick off our experiment

with my personal favourite.

The Eurasian bittern.

We know these birds from reedbeds in the UK,

so they live in this dense environment.

They produce these very low sounds,

booming we call it.

Let's see how low frequency they really are.

Because they're not that large,

but they're making a low frequency sound.

So, Fabian, take it away.

Can we make it louder?

Yeah.

BOOMS

I can see that being eerie in an English countryside.

-Misty.

-Misty.

Reeds, early-morning, or at night.

It's a little creepy.

Even though it sounds really low to us.

It's not that low, is it?

It's not that low.

And so what we're talking about when we talk about what T-Rex would have

produced, or could have produced.

-This is nothing, it's much lower than this.

-Exactly.

Of all the living birds, the ostriches

make one of the deepest calls.

But they're still only a fraction of the size of a T-Rex.

So to create the sound of a much bigger bird,

we artificially drop our bittern call by two octaves.

-All right.

-OK.

-Crank it.

It seems subtle, but you know, it's deep.

-Yeah.

-I can barely hear it.

But deep doesn't necessarily mean quiet.

No.

This is low.

But we haven't yet hit the infrasonic lows

that T-Rex's inner ear implies.

We're going to need to try something else.

We know that animals use infrasonic sounds

to communicate across vast distances.

Elephant rumbles travel miles.

Blue whale song can be heard across entire oceans.

But amongst T-Rex's living relatives,

only the crocodilians share this infrasonic vocal ability.

So, let's put an alligator call into a T-Rex voice box.

So, what does it sound like if we take the Chinese alligator,

and we now move it a couple of octaves lower?

If we move it three octave lower it sounds like this.

BOOMS

Can we get it a little louder?

-Just crank the fader, please.

-OK.

That's ominous.

That is very ominous.

What I really like, Julia,

is that this could be the first time for 66 million years

that this sound has been heard on Earth.

It is pretty incredible.

I mean, it is a shot in the dark,

-but we're using the evidence that we've got.

-Yeah.

If it sounds like this, I mean, I feel like this just induces fear.

You know, I think people think you need to have a roar

for something to be really scary.

But isn't that the scariest sound that you've heard?

Well, it's the scariest sound that I've felt.

-That's the thing, isn't it?

-Yeah.

Tristan the T-Rex is really taking shape.

We've fleshed him out, road-tested him, and giving him a voice.

Now it's time for a little beauty treatment.

An animal's external appearance is a reflection of its biology,

its environment and its social world.

So, what should Tristan look like?

Well, his repto-birdlike nature

means we should coat his body in scaly skin.

But what about the colour?

We know that some contemporary reptiles are very brightly coloured.

Think of coral snakes, reds and yellows, blues even.

Maybe, T-Rex was like that.

Maybe, but T-Rex was a large predator.

So, it's fairly obvious that he would've needed camouflage.

Think of tigers, solitary hunters.

Hunting in forest.

Dappled sunlight, stripey.

So, maybe a stripey T-Rex.

There are other ways to hide, of course.

Spotted, like a leopard, perhaps.

Or maybe such a big,

obvious hunter would need to hide in the shadows of the night.

That would need a very different colour scheme.

Think of all those nocturnal mammals

that we've got these days that aren't related to one another,

but have come up with the same solution.

We've got badgers, you've got skunks, you got raccoons.

All with very prominent black and white patterning on the head.

Maybe T-Rex was like that.

I don't like maybes.

So, clearly I need to narrow down the possibilities.

In a lab in Austin, Texas,

Julia Clark analyses tiny samples of fossilised dinosaurs.

Like, that one is wet, it's about 1.5...

So, I've tracked her down again to help me in my quest.

This is a whole new field of palaeontology, isn't it?

You're looking at dinosaurs under an electron scanning microscope.

I know, is kind of ridiculous, right?

You have these huge animals that you're trying to make sense of,

but yet, to find some insight into how it would have lived,

or what it would have looked like,

we've got to look at its tiniest parts.

But they might bring out some of the most exciting secrets.

The colour of dinosaurs.

Yeah. I love that.

I absolutely love that. That's fantastic.

Under an electron microscope, the samples reveal hidden information.

Structures that contain pigments.

But it's not looking good for a brightly coloured T-Rex.

There are many pigments that are used in nature,

and some of these pigments create very bright colours.

But, we don't have any evidence, at present,

of them in the dinosaur fossil record.

But the structures they have found contained melanin,

the same biological pigment that gives us a tan.

And one group of T-Rex's living relatives

could provide a perfect colour template.

The birds of prey.

What we can say is that living birds that are meat-eaters,

that are carnivores of some kind,

have an ecology that is somewhat similar,

at a very different scale from T-Rex,

and they do not tend to be brightly coloured.

According to Julia's research,

the evidence is that T-Rex's predatory lifestyle,

puts his colouration squarely in line with these contemporary birds.

I think that T-Rex would have been coloured in a palette of browns,

blacks, maybe lighter tones, greys even.

And, that these colours would have been distributed in patches over the

body, maybe breaking up the body outline.

Potentially serving in camouflage,

but also parts of the body that might be a little more dramatic.

Colour is often more intense around the eyes.

And this could help explain another fascinating feature

that Larry showed me in his analysis of T-Rex skulls.

So, we look at the skull and we see these area of roughening that is

almost certainly associated with fleshy display structures,

so they may have well have used those for colour.

But also what could be courtship signs.

They might have communicated information about age,

males versus females.

These were the kind of social cues that T-Rex would have used

to interact with other members of the same species.

So, with Julia and Larry's findings, let's colour up Tristan.

Melanin tones, and patterning for the body.

And a touch of melanic orange around the eyes.

He's looking good.

But, if we are using birds as a guide,

wouldn't Tristan have also had a coat?

And let's be clear, he wouldn't be the first feathered dinosaur.

Feathers evolved directly from reptilian scales.

In fact, we already know that some dinosaurs

were flying about 80 million years, before T-Rex even existed.

One of the first was Archaeopteryx,

and Julia has one of its feathers.

All right, so you have to look at this.

So, this is 149 million years old.

149 million.

It looks like it was pressed there yesterday.

Absolutely. So, you see that centre part where the rake is,

and then branches, which are the barbs.

And then what locks it together tightly are these barbules,

that have tiny hooklets that lock the feather into form.

Just like a modern bird, and yet this is 149 million years old.

And what colour, can you tell what colour that feather was?

Well, other groups looked at the

fossilised malanosomes in this feather,

and they are consistent with a pretty dark tone.

So, maybe like a black, or there

could be some gradations in black,

some subtle tonalities,

but overall quite dark in colour.

And these feathers clearly evolved millions of years before T-Rex.

-Absolutely.

-So, could T-Rex have had feathers like this?

Well, the short answer is no.

Right.

No. T-Rex didn't evolve from these flying dinosaurs.

But recent discoveries in China have unearthed some of his relatives,

and they prove that Tyrannosaurs did

indeed have a simple form of feathering.

So, if we look at this cassowary that's been checking us out,

these are much more simple bristle structures.

They're like the centre part of the feather,

but without any branching structures to the side.

So here there are big,

stiff structures that are on the wing of this cassowary,

which is really tiny.

But even around the face,

we can see simple structures here under the beak,

and even kind of in the eyebrow zone above,

that are like single filaments.

And that's what we find in relatives of T-Rex from China.

So, what does this mean for Tristan's flamboyant feather coat?

Well, it certainly didn't look like this.

For one thing, with so much insulation,

such a large animal would simply overheat.

But the evidence suggests that he would have sported a sparse coating

of these feathery Tyrannosaur bristles.

Now that's an attractive chap!

So, we've got the measure of Tristan's hunting style,

his walking style,

and his appearance.

But what can we uncover about his family structure?

These are the Alberta Badlands, just across the border from Hell Creek.

There's startling evidence for T-Rex's social structure

hidden in this landscape.

Whilst exploring these hills,

Dr Phil Currie uncovered a game-changing set of bones.

You see, this spot was the scene of a terrible tyrannosaur tragedy.

The fossilised remains of 26 Albertosauruses,

close relatives of T-Rex,

were found lying in a group side by side.

They died together, possibly in a cataclysmic storm,

and never before had so many Tyrannosaurs

been found in one place.

Remarkably, they were a mix of young and old.

The smallest animal we have in here was about two years old,

and the largest animal was about 24 years old.

Until this find, Tyrannosaurs were thought to be lone rangers,

but this discovery gave strength to the idea that, instead,

they existed in family groups.

I'd never really thought about

parental care and tyrannosaurs before,

because we tend to think that these animals are quite self-sufficient.

But when you start finding juvenile animals that are living with a large

number of adults, then you have to start thinking

about family structure and these things.

So these animals were definitely together for a reason.

That reason could not have been mating,

because that wouldn't make sense to have the juveniles around at that

-point in time.

-Quite, quite.

And I just think it makes perfect sense that,

if these animals were moving together,

that, in fact, they were hunting co-operatively.

And of course, pack predators aren't unusual.

Africa's apex predator, the lion,

lives and hunts in a family unit, the pride.

And there are plenty of advantages.

They can protect one another, help raise the young,

and there's plenty of opportunity for mating.

But males also fight for dominance,

often causing deep facial wounds.

Tantalisingly, adult T-Rex skulls are also scarred.

These animals were actually biting each other in the face.

And we know that it must have been T-Rex,

because no-one else is biting T-Rex in the face

other than another T-Rex.

These face biting behaviours may have been part of the mating rituals

for these animals, we don't really know for sure.

One thing we do know is that features like these scars

on their faces show that these animals

were interacting with each other in routine and regular ways,

because we see lots of them.

But the real advantage of living in groups comes with the hunt.

And Phil believes that lions offer some real clues

about the social life of Tyrannosaurs.

Very often what happens,

it's the young lions and lionesses

that are the ones that do most of the hunting. They do the running.

Very often, what they'll do is they'll chase a herbivore

back towards the jaws of the adults, the ones that have the real power.

T-Rex packs may have had an extra weapon in their hunting arsenal,

their fast-moving young.

We know this because the bones of juveniles show them to be markedly

different to the adults.

Tyrannosaurus Rex is an animal that just went through incredible changes

in its lifetime, and juvenile animals would have had

very long legs, it would have been very lightly built,

it would have been fast and agile.

Even its jaws are very slender,

and its teeth are quite small compared to the size of the animal.

Young T-Rex was so different to the adult version,

that until recently scientists thought they were separate species.

In his lab in Florida,

Greg Erickson has been investigating the secrets of this transformation.

By slicing through fossilised T-Rex bones,

he's revealed their annular growth rings.

Ageing a dinosaur like Tyrannosaurus Rex is very much like ageing a tree.

Dinosaurs put down annual growth lines,

you can see some of them here.

And simply by counting up the total,

we can figure out how old an animal was at the time of death.

The rings reveal that at about 12 years of age,

T-Rex began the mother of all adolescent growth spurts.

The increasing gaps between rings indicates that, in just a few years,

T-Rex grew three times in height and six times in weight.

In its teenage years here,

this animal was putting on about five pounds of weight per day.

It's mind-boggling.

This extreme growth gave T-Rex the ability

to develop its secret weapon in adulthood,

that almighty head and its massive bite power.

But it also defined it in another way.

As its enormous body grew, its forearms were left behind.

They were effectively the arms of a child.

Tristan the T-Rex is almost complete.

Now, we can only speculate on the true extent of his social world,

but we know this ultimate hunter

would have borne the marks of a violent life.

And for me, the idea that he lived and hunted

in a pride like a modern-day lion, is fascinating.

And it's this that's encouraged me to add one final,

yet plausible touch to my dinosaur.

What about... I like this idea.

What about if T-Rex had a mane like a lion?

We know that male lions use those manes

to communicate to other male lions, and to females.

So, T-Rex with a mane?

A spiky crown for the king of the dinosaurs.

After 65 million years, Tristan is whole again.

Time to set him free.

You know, this journey has been a revelation.

Even as a child I suspected we'd got T-Rex wrong,

but I'd have been amazed at the progress

we've made in the last few years.

What we've discovered about his brain, his appearance,

his behaviour and his voice

have enabled me to strip away the myth and put

real life into that 50-year-old monster at the bottom of my garden.

Now, where are you, Tristan?

T-Rex was no tail-dragging dullard.

He was as real as any animal alive today.

A clever, agile predator,

with senses keen enough to track me down.

He bore the scars of a violent life,

and the colours and plumes of a social creature...

..capable of summoning his kind with a stomach-churning rumble.

When I was a boy, he was the product of my misled imagination.

But now, he's so much more real.

He has such clarity, I can almost...

Well, maybe not.

We've successfully chipped away at his mystery.

This wondrous animal is far better understood

shorn of the errors of the past.

And I, for one, think he'd be pleased

that we're finally much closer to the truth about T-Rex.