The Truth About Killer Dinosaurs Page #2

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that T rex really did attack Triceratops.

But amazingly, the fossil evidence does exist...

John Happ has some more fragments from a

Triceratops, this time dug up in Montana, USA.

First a fossil of a damaged horn...

When we first

found the left brow horn we were disappointed

because about a 1/3 of the horn is missing.

These are bite marks....

... the end of the horn was bitten off.

The shape of the teeth marks proves once again

that the culprit could only be T. Rex

Bite marks alone

still don't prove T. Rex attacked Triceratops.

But John has noticed something else.

We found some additional bite marks.

A line made where T. Rex's tooth

raked into the frill.

But there is something strange about this line.

Where you might expect a clean-cut groove

from the tooth - there is an unusual ridge.

And when John x-rays the ridge

the incredible truth is revealed.

You can see at the first score

mark an area of dense bone.

This is an indication that the bone re-healed.

The bone re-healing is the crucial evidence.

It proves that Triceratops was attacked

by T. rex while it was alive.

Triceratops must have survived for long enough

for the wound to heal.

It's the first time scientists can say

for certain that T rex

wasn't simply a scavenger -

because they know that,

at least on one occasion,

it did attack Triceratops.

They know that T rex grabbed its horn.....

and broke it...

They also know that T rex grabbed the frill

of the same animal

with enough force to crunch through bone.

But there is still much more to discover about

the relationship between these two heavyweights.

If T rex ambushed Triceratops

he would have had to been quick.

So how fast could T rex run?

He's been depicted as everything from a lumbering

hulk to an animal that can out pace a jeep.

Some have even speculated that these legs

could power him up to 45 mph.

So what's the truth. ?

Jim Farlow of Indiana University

is investigating

one of the world's finest collections

of footprints of meat-eating dinosaurs.

Here's a real nice one right here,

starts out here with a left footprint and then

we go here to the next right footprint

and beyond here is another left footprint

of the same animal.

By measuring the distance between the footprints,

Jim can calculate

how fast this dinosaur was moving...

Well judging from the length of the stride,

l, d guess that this beast

is moving at a fast walk...

maybe 7-8 mph which is sort

of a fast jog for a human being.

So can these footprints help scientists

to work out the top speed of T. Rex?

Well there's a problem because T rex was much

larger than the dinosaurs that left these prints.

Now if we had a tyrannosaurus stride....

and if we start at about

where that footprint is...

the same foot would now come down....

going to be about here.

And that's just a walking stride...

So you can see in order to encompass the entire

length of stride of a running tyrannosaurus -

you're going to have to have a very big surface

and it might be hard to get one that large.

In fact no footprints of a running

T. Rex have ever been found...

So to consider how fast a tyrannosaurus could run,

we may have to use something

other than footprints.

John Hutchinson is studying the way animals run

at the Royal Veterinary College

in Hertfordshire, England.

He's trained Sharon the ostrich

to work-out on a running machine.

And she's helping him work out

how fast T rex might have run.

Ostrichs, 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.

Look at this ostrich....

an ostrich can run faster than any human.

How does it do that?

Well it has huge leg muscles about 15%

of the body weight in this ostrich.

Those muscles produce a lot of force.

In fact they can power Sharon's legs

up to an impressive 40 miles an hour.

These leg muscles help the leg work like a spring

and the body is acting like a great weight

that is bouncing up and down on those springs...

much like a pogo stick.

That's what makes the ostrich such 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.... simply impossible.

Clues from the bones suggest that it probably

had muscles much more like this.

So T rex was definitely slower than an ostrich.

We figure from our calculations that a T. Rex

might be able to move as fast as 25mph maximum,

probably a bit less than that.

It doesn't sound that fast but

it's as fast as an Olympic sprinter

and those speeds aren't bad

at all for an animal that big.

25mph if you saw a T. Rex going

that fast would be very impressive.

T Rex could run faster than most humans,

but could it run faster than Triceratops?

Triceratops was built rather like a sumo wrestler

and its short front legs would have

made big strides impossible.

John Hutchinson has calculated that

Triceratops could run no faster than 15mph.

So now its obvious as to who would catch who.

But is it?

Triceratops had one more trick up its sleeve...

Scientists are comparing the agility

of the 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 2 legs.

The problem that T-Rex had is that the legs

were in the middle and they had a long body,

head and neck out in front and

then a long heavy tail out behind.

T rex has a pivot in the middle

with a considerable

amount 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?

Well, this experiment requires

a certain amount of imagination....

Dave's the Triceratops, his student is T rex.

In the pack on my back is twenty six pounds the

same weight as the T-Rex behind me is carrying.

The difference in the T-Rex the weight is a metre

in front of the legs and a metre behind the legs,

in my case l, m much more similar

to the triceratops,

in that the weight is carried close to my back.

If we were 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.

First turn to the left.... To the right....

Left.... Triceratops is gonel

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...

Perhaps by losing those huge teeth?

Or reducing the size of its head?

Obviously T-Rex can't change its anatomy,

if it had it would no longer be T-Rex.

After all it's the big head and big teeth

that give this superstar its Rex appeal.

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