Planet Dinosaur: Ultimate Killers

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(GROWLING)

JOHN HURT:
We are living

through a dinosaur revolution.

We have pushed the boundaries of

our knowledge further than ever before.

(ROARS)

We have a completely new understanding

of the greatest killers

ever to walk the Earth.

(GROWLING)

One killer, first discovered in Egypt,

has become the icon

of these new predators.

A giant dinosaur, with two-metre-long

spines rising over its back.

It was unlike anything seen before.

It was only in 2005,

when a complete upper jaw was found,

that we could accurately reconstruct

this bizarre creature.

With a skull almost two metres long,

this dinosaur was a colossal 17 metres

from nose to tail.

Four metres longer than T-Rex.

The reign of the dinosaurs began

almost 250 million years ago,

but this killer didn't appear until

a time known as the mid-Cretaceous.

95 million years ago,

its home in North Africa

was a desert surrounding

a vast system of rivers and swamps.

The swamps are refuges

for many large dinosaurs,

like the duck-billed Ouranosaurus.

(SQUAWKS)

(CALLING)

They are also the hunting grounds

for a killer.

(CALLING)

(GROWLING)

Spinosaurus,

the biggest killer

ever to walk the earth.

An 1 1-tonne colossus.

However, for the time being,

these Ouranosaurs

are off this killer's menu.

Spinosaurus is part of a relatively

newly discovered family of dinosaurs.

They've been found in South America

with Irritator,

in Europe, there's Baryonyx,

and Asia, Siamosaurus.

But the last and biggest of all

came from North Africa:

Spinosaurus itself.

And studies of their bones and teeth

revealed something amazing.

Spinosaurus is a predator,

but one that hunts in water.

Spinosaurus is unique.

With long, narrow jaws and nostrils

set high on its head,

its teeth were straight and conical,

and it had a curious pattern

of holes in its snout,

which give us a clue to how it hunted.

These are Onchopristis,

eight-metre-long giant sawfish.

In 2008, a Spinosaurus skull

was put through a CT scanner.

It revealed that the holes

and sinuses in the snout

looked just like those of crocodiles.

It's thought these contained

pressure sensors.

Sensors that, like a crocodile,

can detect the movement of prey.

It can strike

without even seeing its victim.

Anywhere else, this eight-metre Rugops

might be the top carnivore.

But here, it is dwarfed by Spinosaurus,

a predator that adapted to exploit

an environment so successfully

it evolved into a 17-metre giant.

Spinosaurus is the biggest

dinosaur predator ever discovered,

but it wasn't the first giant killer.

The first giant killer dinosaurs

appeared much earlier.

They lived in the Jurassic period,

1 50 million years ago.

One of the most iconic is Allosaurus,

from the Morrison Formation

in North America.

Yet it's only recently that

we have been able to work out

how these predators hunted.

(WIND HOWLING)

(SNUFFLING)

Allosaurus is the most common killer

in these lands.

Nine metres long, with a battery

of saw blade-like teeth,

Allosaurus is a formidable hunter.

A lone Camptosaurus

should be an easy kill.

Allosaurus teeth were serrated

front and back,

perfectly evolved

for tearing through flesh.

However, recent research has indicated

that Allosaurus's bite was

surprisingly weak.

Calculations suggested its bite

was less powerful than a lion's.

So just how did thisJurassic monster

hunt and kill?

(SQUEAKS NERVOUSLY)

Camptosaurus relies on its keen senses

to avoid predators.

Allosaurus, on the other hand,

is a fast and powerful ambush hunter.

(ROARING)

(GROANING)

(MOANING WEAKLY)

(ROARING)

Despite the apparent

weakness of its bite,

Allosaurus did, in fact,

have a deadly killing method.

Its skull could withstand a force

more than 1 5 times as great as its bite.

This meant that Allosaurus

used its head like an axe,

its strong neck muscles

driving its top jaw into its prey.

With every impact, the serrated teeth

would tear through its prey's flesh...

the victim dying through

a combination of shock and blood loss.

(ROARING)

Saurophaganax.

At 12 metres, it is the biggest

carnivore in the region.

(ROARING)

(BOTH ROARING)

One of the advantages of being so big

is that stealing another's kill

is that much easier.

With the rise of giant predators,

and their spread

throughout the Jurassic world,

smaller dinosaurs needed new strategies

if they were to survive.

In recent years,

China has been the focus

of some remarkable fossil discoveries.

One extraordinary fossil hints

how some may have avoided

these killer dinosaurs.

It lived in the Jurassic forests

of China 1 54 million years ago.

Hiding in these lush forests

is Epidexipteryx.

This forest is home to many predators,

and being small makes it vulnerable.

(DISTANT ROARING)

This is Sinraptor.

A small dinosaur like Epidexipteryx

would be of no interest

to a seven-metre adult.

But this is a juvenile.

(ROARING)

Being small does have its advantages.

Everything we know about Epidexipteryx

comes from an incredible fossil

first revealed in 2008.

It showed an animal with a small skull

and large eye sockets

and unusually long teeth,

with toes suited to gripping branches

and very long arms and hands.

It suggests that this was a dinosaur

well suited to living in the trees.

The extraordinary

elongated third finger

is another distinctive

feature of the group.

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