Dinosaurs! We've seen 'em in the movies,
on telly, in books.
And, you know, considering they died out 65 million years ago,
we know an awful lot about them.
Or do we?
just how much of what we see and read is, in fact, accurate?
Well, we're going to be separating fact from fiction.
We'll be putting T rex and triceratops, two of the giants of the dinosaur world,
through their paces.
We'll test and challenge the latest theories.
And, by building life-size biomechanical replicas,
we'll reveal their devastating power...
for the first time ever.
We will be giving you the true facts
about some of the most daunting and dangerous creatures
that ever walked the earth!
A primordial swamp.
Well, actually, it's the Florida Everglades.
But this is perfect habitat for birds and for alligators.
And millions of years ago, it would have been perfect habitat for dinosaurs.
I saw my very first living, breathing dinosaurs when I was a little lad,
and used to go to the Saturday morning pictures.
(B-movie voiceover) Starring the gigantic predator,
tyrannosaurus rex, locked in mortal combat with the terrifying triceratops.
But did that sort of thing really happen?
Is there any scientific proof
that tyrannosaurus rex was an invincible predator,
capable of vanquishing any triceratops it happened to come across?
Well, it's also a question that scientists have been trying to answer,
ever since they found the first fossil bones.
So, with their help, we've faithfully reconstructed
the two most iconic dinosaurs of all time, to find out the truth.
And what I've discovered, frankly, has surprised me a very great deal.
And I'm pretty sure it's going to surprise you too.
So, let's examine the evidence.
First of all, what do we really know about tyrannosaurus rex?
We all know the name, we probably know what it looks like,
and we most certainly know its reputation -
big, bad and dangerous to know.
But all the scientists have to go on are fossil bones.
What's more, the first T rex was only discovered about 100 years ago
and since then, they've only found another 25 more skeletons.
And here's a thing - not one of them is 100 per cent complete.
Even the very best five or six - and this one's pretty good -
have got a few bits missing.
Maybe the tip of the tail or a toenail, or a tooth.
But he's had plastic surgery, so he's looking pretty good.
What are you up to?
So, what can we tell by looking at this skeleton?
Well, it's big.
Ah, yeah, but how big?
It's something like 40 feet long, that's longer than a double-decker bus.
Up to the hips, 12 feet. The head alone, five feet long.
All of which confirms my theory that it is big.
In fact, it's huge.
But, erm, what about its finer faculties?
Look at various holes in the skull -
they should be able to tell us something about how it sees, how it hears,
its sense of smell, and its brain - how it thinks.
That is, if it thinks at all.
By looking even closer at the skeleton,
the scientists can see where the muscles and the tendons attached.
They can even tell the texture of the skin
by studying impressions left in the ancient rocks.
So, using all the scientific evidence, we can now breathe life into our T rex.
It's certain that T rex was absolutely enormous and pretty fearsome.
In fact, a real bruiser.
Nevertheless, was he really capable
of overpowering the other big guy on the block?
Triceratops - old three-horned face.
The most famous of the horned dinosaurs.
At eight tons, this would certainly have been a super heavyweight
for T rex to take on.
We've only got three fossil skeletons of triceratops to go on
and none of these are complete.
But we can tell from its size and its huge skull
that this dinosaur would have made a formidable opponent.
Mind you, that beak-like mouth tells us that it was a plant eater,
probably not the type to go looking for trouble.
So, although triceratops definitely lived in North America
at the same time as T rex, did they ever fight?
In fact, is there any evidence at all that they had anything to do with each other?
These questions have been keeping the scientists glued to their fossils.
I went to meet Greg Erickson, who has an amazing fragment of a pelvis
from a 65 million-year-old triceratops.
On the pelvis, he's found some intriguing wound marks.
If you look here, there's some gouges along the top.
There's a really deep puncture mark right here.
If one looks all over this specimen, you'll find 80 punctures and cut marks.
These are bite marks.
So, who was the culprit? Who'd been chomping chunks out of this triceratops?
We have a real whodunnit mystery here.
But Greg was on the case.
Using a standard forensic technique, he pushed some dental putty
into one of the deep wound marks, in order to identify the mystery diner.
Aha! There we go.
I have a very nice cast here of the tooth.
This shape is very familiar to me, it looks like a therapod dinosaur tooth.
And it's a very nice match for the tooth of this animal, tyrannosaurus rex.
I think this is pretty good smoking gun evidence
that tyrannosaurus rex fed upon this triceratops 65 million years ago.
So, this is the first time that we can say for sure that T rex did,
at the very least, eat triceratops.
But did T rex have to fight for its supper?
I mean, possibly, it just found this dead animal lying in its path.
We still don't know for sure that T rex actually killed triceratops.
To do that, he'd have needed some pretty serious weaponry.
And he'd have to be pretty fearless too.
So, er, was he?
Be honest, it's pretty hard to imagine T rex being scared off by...
well, by anything, actually.
Look at the size of it, it's absolutely enormous,
it's covered in muscles,
and it's got just about the scariest mouthful of teeth
this side of a great white shark.
There's no less than 50 of them in there, so it won't miss one, will it?
Come on, come on! Don't worry, this won't hurt a bit, you won't feel a thing.
Let go! It's got to come out!
Right. There.
Look at the size of that.
These look like they could do some real damage.
And we have seen that they could make holes in triceratops'pelvis,
but the question remains,
could T rex actually have slaughtered a live triceratops?
Well, it's difficult to know,
when all we've got to go on are some rather decrepit fossil bones.
If we want to know exactly how much damage those jaws can do,
we're going to have to build a life-size, totally accurate,
fully working model of a T rex head.
And the model is going to be based on Stan,
one of the most complete T rex skulls ever found.
It'll be made, by hand,
faithfully following the proportions of the T rex fossil.
And during its construction, scientists will be consulted every step of the way,
to ensure we get it right.
Our model will have to be incredibly strong
because we know that when T rex was feeding,
he could bite right through bone.
How much force should we use to power its jaws?
Scientists can tell from the skeleton that T rex had huge jaws.
But before we can test whether T rex
was tough enough to take on a living triceratops,
we need to know exactly how powerful these muscles were.
What we need to do is get hold of one of T rex's closest living relatives,
for example, an alligator.
Now, alligators do have one of the most powerful bites in the world.
So, if we can actually measure the force of an alligator's bite,
we should be able to scale it up to get the force of a T rex bite.
OK? So all down to the zoo to find a nice friendly alligator.
Unfortunately, apparently alligators in the zoo get a bit lazy
and they begin to lose their chomp.
We have to get one in the wild.
Well, when I say "we" have to get one,
I mean Greg, who showed me the T rex bite marks, is going to get it for me.
When Greg's not studying fossils in his lab,
he's out and about investigating live animals
to help him calculate the force of a T rex bite.
He's hitched a ride with the Florida Alligator Control,
who are hoping to catch a rogue gator who's been rather upsetting local people
by eating their pet dogs.
Crikey! She's a fine one.
Yes, indeed! A whopping 12-foot animal, weighing about 450 pounds.
That's about the same as three men, or 30-odd poodles.
And a Chihuahua.
Now we have our wild, rogue alligator.
The perfect subject for our bite test.
Yeah, looks a little bit snappy to me,
so I think I'll keep out of the way while Greg inserts his bite-ometer.
OK, jaws are free.
- Ready? - Yeah.
Here we go.
There we go, nice bite!
2,209-pound bite.
- One ton. - One ton! Sounds a lot, don't it?
Now Greg is going to scale that up
to work out how strong the bite of a T rex would be.
Man! OK, we're close to release, everyone ready?
Tony, you ready? OK. Hang on.
- There it is! - That would've left a mark.
So, based on his work with alligators,
Greg calculated that Stan here
would have had a bite force of at least four tons, that's 8,000 pounds,
or, would you believe this, 35,000 newtons.
Now, of course, this means... absolutely nothing to me.
But what I do know is, the bone would have had to be so strong,
that the only way we can replicate it is by using steel.
So, Stan,
meet Dan.
Steely Dan? No.
Anyway, the muscles to operate these jaws
would have had to be massive.
We've had to use sort of a hydraulic piston.
OK, then. I think it's time to give the dog a bone.
So this is just part of a cow's leg bone.
Pop it in there, to do this, very docile.
There you are.
Have a chomp on that, then.
Oh, and another thing...
I mean, a predator doesn't slowly open its jaws
and slowly close its jaws when it's after a live prey, does it?
You know, ''Excuse me, may I just chomp you?'' No.
It leaps forward and...snap!
So let's see what that is - four tons, T rex,
leaping out onto prey, and...snap!
(Crunching)
Whoa, yes! Pretty impressive.
I think we'll try another one, shall we?
And another one for luck.
So, I think we can safely conclude
that T rex could definitely deliver a killer bite.
But our biomechanic test still doesn't prove that T rex really did attack triceratops.
No - I still needed to find the hard evidence.
I went to see john Happ,
who promised me he had some fossils that would blow me away.
And he was right.
They were some more remarkable fragments from a triceratops,
this time dug up in Montana, USA.
The first one he showed me was a fossil of a damaged horn.
When we first found the left brail horn, we were disappointed,
because about a third of the horn is missing.
And on close examination,
there's a conical depression on the top of the horn,
and another conical depression in the bottom of the horn.
These are bite marks, the end of the horn was bitten off.
And the shape of the teeth marks proved, once again,
that the culprit could only be T rex.
But bite marks alone still don't prove that T rex attacked triceratops.
However, john had noticed something else.
Close to the left brail horn, on the frill,
we found some additional bite marks.
There was a line, made by T rex's tooth raking into the frill.
But there was something strange about this line.
Where you might have expected a clean-cut groove from the tooth,
there was an unusual ridge.
And when john X-rayed the ridge, the incredible truth was revealed.
You can see, at the first score mark, an area of dense bone.
This is an indication that the bone rehealed.
Aha! There you are!
The bone healed.
Now, that proves that triceratops was attacked by T rex while it was alive.
And triceratops must have survived long enough for the wound to heal.
If ever there was a holy grail of fossils,
then john's small bone fragment might well be it.
It's the first time we can say for certain that T rex wasn't simply a scavenger.
We now have evidence that it did attack triceratops.
We know that, in this instance, T rex grabbed triceratops' horn, and broke it.
We also know that T rex grabbed the frill of the same animal
with enough force to crunch through the bone.
And most extraordinary of all -
we know that this triceratops lived to tell the tale.
So - maybe the bumbly old lumbering,
three-horned vegetarian wasn't a complete pushover.
I mean, after all, it survived an attack
by what we think of as one of the most vicious predators that ever lived.
I mean, yes, yes, it lost a little bit off one of the ends of its horns
but surely it was those horns that saved its life.
They certainly look pretty dangerous, don't they?
And it's perfectly possible that they were used
as a very effective offensive weapon.
But if they were, how exactly did it use them?
Get off! We'll have none of that!
I asked Andrew Farke, who's one of the foremost experts on horned dinosaurs.
It's easy to think that triceratops, when confronted by a hungry T rex,
something that's threatening it,
would have immediately charged and used its horns with all its might.
There is an animal living today, with a very similar build,
that could perhaps give us a clue to how triceratops saw off its attacker.
The animal that comes to mind is a rhinoceros.
The rhino has a vicious-looking horn on its nose, and when it's provoked,
it'll charge at full pelt, using all its weight to ram its opponent.
So, at first glance, it might appear that triceratops was charging like a rhino.
Yes indeed, it sounded like a reasonable theory. But we needed to test it.
To find out exactly what kind of damage
a charging triceratops would have inflicted on T rex,
we decided to build a life-size model of a triceratops skull.
First, we had to find a material that had the same properties as triceratops bone.
So, our specialist building team
exhaustively tested various resin composites.
We had to ensure our replica behaved just like a real animal in an impact.
To conduct an accurate test,
we also needed to know how fast triceratops could run.
It definitely wasn't a fleet-footed athlete - it was built more like a sumo wrestler.
Based on this, and the fact that its little short front legs
made big strides impossible, we can be pretty sure that triceratops
could run at no more than 15 miles per hour.
Right, a team of experts has been working for months
to meticulously prepare our test.
We have an accurate model of the skull,
built from a specially-developed resin composite.
We have a top charge speed of 15 miles an hour
and we have a weight for a triceratops of five to eight tons.
And now, we have the test.
A crash test.
Here, in this hangar, they normally crash-test cars.
And yet, so far, very few dinosaurs.
In fact, none. So, this is definitely a first.
It's a unique experiment on a truly spectacular scale!
We're going to get the whole thing to come thundering down here,
straight into a head-on collision - wham! - with...
That's right, tyrannosaurus rex.
Not quite such an elaborate model, I agree, but it's got all the qualities.
The muscle and flesh of T rex is represented by crushable honeycomb aluminium.
This is covered by the T rex skin, made from thin sheet aluminium
and tastefully realistic leatherette.
So, use your imagination.
Come on, just imagine it, standing there, head down,
standing its ground, waiting for the charge.
For the first time ever, we are going to find out what would've happened
if triceratops charged at full speed into the belly of T rex.
That is fast!
Ah. Yes. Well.
I think it's pretty safe to say
that from triceratops'point of view, it wasn't an unqualified success.
Let's fact it, that would have hurt.
Quite a lot.
And in slow motion, we can see exactly what happened.
The sharp, narrow horns penetrate easily into our T rex,
but the broader beak and nose
simply couldn't cut through the flesh and muscle.
Force is built up to six tons and the triceratops' skull started to fail,
fracturing at its weakest point.
The skull clearly was not strong enough for triceratops to charge like a rhino.
So, we still don't know how triceratops survived an attack by T rex.
But in my experience, the outcome of many a predator/prey battle
is often determined by who sees who first.
How well could T rex see?
Now, that's a difficult one,
because when an animal dies,
amongst the very first things to disintegrate are the eyes.
Nevertheless, there are clues.
In fact, we can tell quite a lot about a dinosaur's eyesight
by examining the skull.
So, eye socket, quite big. Eyeball, also pretty big.
In fact, about the size of a grapefruit,
meaning lots of room in there for those fibres and sensors
needed to have pretty sophisticated vision.
But, erm, did it see in colour?
Well, most mammals see in black and white
but birds and reptiles see in colour,
and birds and reptiles are, as it were, distant relatives of, yep, dinosaurs,
so it's fair to assume that T rex saw everything nice and clear
in glorious Technicolor!
Good eyesight would have been very useful
when it came to spotting and hunting down prey.
Kent Stephens has been using laser measurements
to investigate the link between the position of T rex's eyes
and its hunting techniques.
Modern predators, like cheetahs, who chase down their prey,
have eyes right at the front.
This gives them good 3D vision,
and better allows them to keep their victims in their sights.
When Kent measured the eye position of T rex,
he was surprised at what he saw.
In the case of T rex, I didn't see just a very large reptile,
this is closer to, like, a wolf.
The snout drops down relative to the plane of the eyes, it becomes narrower.
So this could look down and over its snout,
providing a very broad field of view ahead of it.
The position of T rex's eyes gave it the advantages of a modern hunter.
So, it was certainly able to chase down triceratops.
But how well could triceratops see T rex coming?
If you look at animals today that need to keep constantly alert for predators,
they have eyes on the sides of their heads.
Kent could see that triceratops was just the same.
It had side-mounted eyes, to keep a lookout for potential killers.
But it also had blind spots.
This whole structure here, the support of these horns,
obscures forward vision.
Another thing is this large frill, this large frill produced a very large blind spot.
It could have compensated for it partly by swinging its head from side to side,
so it could look over one shoulder or another.
It was a potential vulnerability that a predator could certainly have exploited.
Triceratops' spectacular frill might have helped to frighten off some opponents
but, clearly, it also had its flaws.
T rex might well have taken advantage of the blind spot,
sneaked up and ambushed triceratops from behind.
But, er, it still had to make a final lunge,
and to do that, it would have had to be quick.
So, how fast could T rex run?
He's been depicted as everything from a lumbering hulk,
to an animal that could outpace a jeep.
Some have even speculated that these legs could have carried him along
at 45 miles an hour.
In my quest for the truth, I travelled to Texas, USA.
Lying beneath the waters of this quiet river are some tantalising marks.
And they were made more than 65 million years ago.
At the moment, what I'm seeing are these little gouges, little clefts, little holes.
But then, all of a sudden,
you realise there's a very, very obvious shape.
In fact, it's a dinosaur footprint.
Look at that. One, two, three toes.
They've got claws on the end, digging in.
You can just imagine, slightly tippy-toes, like a bird walks.
Wow! Made 65 million years ago and yet it could have been yesterday.
That's astonishing.
Over the centuries, the river has eroded the rock,
and exposed hundreds of these dinosaur footprints.
It really is amazing. They are so old.
But they're still here.
Imagine finding these, you know? I don't know who found them really.
Were they just wandering and said, ''Oh, that looks a bit like... Oh! Another!
''Aaah! Dinosaur footprints!'' It's fantastic!
And the more you look, the more you begin to see lines of footprints.
By measuring the spaces between them,
scientists can work out how fast the dinosaur was moving.
..and right.
Can they tell us anything about T rex?
Right...and left.
The dinosaurs that left these footprints were big but nothing like as big as T rex -
because T rex was at least twice as big.
So, that's the size of this guy's footprint, about there.
T rex footprint, a bit more.
At least that big.
This guy's stride goes from there to...
Next, left foot going down...
About there. So that's the length.
T rex's stride, at least twice as far, so it's gone from back there,
in one great big stride, to...
that's...about here.
That is one stride of T rex and that's only if it's walking!
If it's running, then it takes even bigger strides.
So, it sets off from here, and it runs.
Next time it puts its foot down, run, run, run...
Something like that.
Which means the chances of finding prints that we know are a T rex running
are very small indeed.
In fact they have never, ever been found.
So, if we want to know the top speed T rex can travel at,
we're just going to have to approach it a whole new different way.
Look at these ostriches. What do they remind you of?
Of course! Tyrannosaurus rex!
Yes, they do! Look! They run on two long, thin legs
with great big thighs, just like T rex.
And look at those feet. Yeah? Those aren't birds' feet, surely?
They're much more like...
Exactly - a dinosaur's!
So, ostriches - T rex. Obvious connection!
Don't believe me? Look - we want to know how fast T rex can run.
OK. They're going to help us.
john Hutchinson is studying the ways animals move,
at the Royal Veterinary College in Hertfordshire.
How? Well, by taking them for a workout on a running machine, of course!
john assures me that Sharon the ostrich absolutely loves this.
It keeps her slim and it helps him work out how fast T rex might have run.
Sharon's legs are very similar to T rex's.
Pretty skinny...
with long tendons stretching down to the toes
and all the muscles piled up at the top.
- They're very thin legs, aren't they? - They're thin down low
- but this is all muscle. - Yeah, I can see that.
These muscles power Sharon's legs up to an impressive 40 miles an hour.
Each leg is like a pogo stick
and the leg compresses, then rebounds as the foot goes on and off the ground.
That's what makes an ostrich a fast animal.
It's pogo stick-like legs and big muscles.
So, could T rex run as fast as an ostrich?
By scaling up from Sharon,
john has worked out that to run at 40 miles an hour,
T rex would have needed muscles as large as this.
Pretty impossible. In fact, totally impossible.
Clues from the bones suggest that it probably had muscles more like this.
So, T rex was definitely slower than an ostrich.
We think that 25 miles an hour is really pushing it as the top speed of a T rex.
- That's still flipping quick, isn't it? - It's pretty fast for a big animal.
25 miles an hour is considerable. A rhino can be about...
- But not for long. - An elephant can't go that fast.
T rex could run faster than most humans, too.
And here's the important bit - it was definitely faster than triceratops,
who could only run at about 15 miles an hour.
So, now we know who would catch who.
Or do we?
Triceratops had one more trick up its sleeve.
Or should that be, behind its frill?
Scientists have been comparing the agility of our two dinosaurs
using a rather unconventional experiment on the salt flats of Utah.
Dave Carrier has discovered there is a downside to being a 40-foot-long T rex,
running on just two legs.
The problem that T rex had is that the legs were in the middle
and he had a long body, head and neck out in front,
and a long, heavy tail out behind.
Quite so. If you look at T rex, there's a pivot in the middle,
with a lot of weight spread out on either side.
Triceratops, on the other hand,
had all its weight centred solidly above four legs.
So, who had the advantage when it came to a chase?
You'll have to use your imagination a little here.
Dave is the triceratops and Dave's student is T rex.
In the pack on my back is 26 pounds,
the same weight as the T rex behind me is carrying.
The difference is, in the T rex,
the weight is a metre in front of the legs and a metre behind the legs.
In my case, I'm much more similar to the triceratops,
in that the weight is carried close to my back.
If we're to run straight ahead, as we're doing now,
the T rex has no problem tracking me.
If I were to turn in a gradual arc,
the T rex could track me perfectly fine.
However, watch what happens on the second or third turn.
Turn to the left.
Turn to the right.
Left.
Triceratops is gone!
T rex's body shape put it at a serious disadvantage.
It would have been a lot better off
if it could have reduced the weight at the front end,
er, perhaps by losing a few of those teeth?
Or maybe reducing the size of its head.
(High-pitched squawk)
T rex can't change its anatomy without ceasing to be T rex.
Absolutely, quite so, it's that gigantic toothy grin
that gives our superstar its rex appeal.
(Roars)
Exactly.
What, realistically, could it have done to improve its agility?
One thing it might have been able to do is change its posture when it was running.
Instead of running with the head and neck stretched out horizontally,
they would have actually pulled their neck back into an S shape.
They also have raised the tail up, off the horizontal,
to an angle above the ground.
Both of those changes would have greatly increased the agility of T rex.
But speed and agility aren't everything.
How about cunning?
If T rex was clever enough,
he might have been able to plan his attack and outsmart triceratops.
But then, to know that, we'd have to look inside its brain.
Which is impossible?
Scott Rogers doesn't think so. He's one of the few people in the world
who's tried to get into the mind of a dinosaur.
One of the most difficult aspects of studying the behaviour of an extinct species
is trying to find its brain.
The problem with the brain is, it tends not to fossilise.
Instead, it tends to rot.
Up until now, all scientists had to work on
were the mud-filled spaces inside the skull, where the brain used to be -
the endocast.
But Scott had a clever idea -
to look inside this endocast using the latest medical scanner.
He wanted to see if there were any traces of the brain
left behind in the fossilised mud.
What we found was something quite extraordinary.
For the very first time, we're really looking at material
that we believe reflects the actual structure of the brain.
It really is quite incredible.
The white blobby mass reveals the true shape and structure of a dinosaur brain,
for the first time ever.
And from that, we can work out how T rex behaved.
By comparing that with modern species, what we find is,
that brain, right there, resembles very closely the brain of an alligator.
So, if we study their behaviour,
there's a chance we can figure out how T rex would have behaved.
Now, how can I put this? An alligator's thought process is a little bit simplistic.
Basically, they sense something, they smell it, they hear it, they see it,
and wham! They react.
For example, anything they sense might be food,
they will zap...and swallow.
You don't believe me?
Not a lot of learning going on there, is there?
What they don't do, is think, ''Mm-hm, sounds like food, but it might not be.''
It's quite simply sense, zap, all gone.
just like an alligator,
T rex would sense something and go after it,
no questions asked - fast-jawed, slow-witted.
So, if T rex was, er, well, dumb,
then surely triceratops would have out-thought it.
If we look at this model of a triceratops,
what we find is something strikingly different.
The brain size, in this region, is almost the same size as the spinal cord region.
What this tells us is,
as sensory information came into the brain, it basically went straight through.
In one end, out the other.
T rex was dumb, triceratops was dumber.
It probably did very little when a tyrannosaurus would come up,
it would protect itself, it might charge, but it had a limited ability to respond.
Wait a minute - protect itself?
How?
Our biomechanical crash test has already proved
that triceratops couldn't have charged full speed at T rex, like a rhino.
Come on!
He surely wasn't that dumb!
So, what did it do to defend itself?
Andrew Farke, our triceratops expert, has a new theory.
He's been re-examining some triceratops fossil skulls,
and he's found some tell-tale blemishes that no one had noticed before.
Perhaps there's a bit of bone missing in front of the eye.
On the cheek, you might find an odd hole.
In other specimens, there are abnormalities in the frill.
And from the shape of the marks, he can tell what caused the damage.
Triceratops going horn to horn with each other.
Now we know for sure that triceratops was using its horns against its own kind,
so it's very likely it was also using them to fight off T rex.
But it didn't use its horns to ram T rex,
it must have used them like this - flicking its head to gore its attacker.
Potentially lethal.
But don't forget, T rex had the weapons to fight back.
just like him, it had vicious jaws.
We know that T rex could snap like an alligator
but, er, was that it? Oh, no, no, no, no!
T rex - come on! Much more elaborate than that!
Yes! Talking of jaws...
T rex behaved much like one of the most feared carnivores
on the earth today, the great white shark.
I t didn't just crunch on flesh and bone, it ripped out great chunks of its victim.
How do I know? Well, Greg's been taking a really close look
at the T rex damage on this fossil triceratops.
You see that this animal bit down into the bone and then pulled backward,
removing large chunks of bone and leaving a furrow behind.
Now, if we look at a bite mark made by the great white shark,
such as this one, that was made on a whale vertebra, it's the same pattern.
The tooth was pushed down into the bone here and pulled across,
leaving a furrow, very much like those we see on the triceratops pelvis.
Using our steel T rex head, we're going to see what kind of effect
this brutal bite would have had on a triceratops.
And our stand-in for triceratops is...
a side of pork.
To reproduce the ripping motion,
we're going to use an industrial-strength forklift.
Whoa! OK! Go for it! Go for it!
just like a great white shark.
There were two distinct parts to the bite.
First, a deep, penetrating crunch through flesh and bone.
And then, using its full body weight,
T rex would have pulled backwards, ripping through the flesh.
Quite literally makes mincemeat of triceratops.
Now we've gone to all the trouble of making a biomechanical T rex head,
I think we ought to play with it for a bit, don't you?
Let's see how a 20th-century icon stands up to an icon of a very different era.
Now, this may be fanciful, but it is not an exaggeration.
It's been scientifically calculated that a real live T rex
could have done damage like that.
OK, so T rex could have crunched up a small car.
But, er, it didn't put up much of a fight, did it?
I mean, come on! A healthy triceratops,
that isn't just going to lie there and let itself get clamped.
No, in fact we have evidence that, on at least one occasion,
he definitely did not take it lying down.
But, here we've got T rex,
here we have triceratops, is that really a fair fight?
Well, let's see how they match up.
First, eyesight.
T rex, a predator. Excellent all-round eyesight.
Triceratops - no. Bit hazy, lots of blind spots.
Speed - T rex, very quick going straight but a bit dodgy on the cornering.
Triceratops - not quite as fast but much more manoeuvrable.
And weapons. T rex - jaws, teeth.
Triceratops - three great big pointy horns.
So, how would it have turned out?
Well, if T rex could have hidden
and then leapt out and surprised triceratops,
or if triceratops had been ill or injured,
then I would have to go for T rex.
But, in a full-on, all-things-being-equal, fair fight,
I really wouldn't like to predict. In fact, at the end of the day,
it might be just a matter of who makes the first mistake.
We've examined the evidence, we've tested the theories,
and we can now, finally and faithfully, recreate a titanic confrontation
that might well have happened exactly like this 65 million years ago.
Maybe tyrannosaurus rex wasn't quite so invincible after all.
In the next programme, I'm going to be investigating the two-legged meat eater,
velociraptor.
Much smaller than T rex but no less terrifying.
We're going to build another life-size biomechanical model,
to investigate exactly how this killer dinosaur
used his legendary disembowelling claw.
And I'll be revealing his gruesome secret.