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(GROWLING)
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JOHN HURT: We are living
through a dinosaur revolution.
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We have pushed the boundaries of
our knowledge further than ever before.
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(ROARS)
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We have a completely new understanding
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of the greatest killers
ever to walk the Earth.
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(GROWLING)
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One killer, first discovered in Egypt,
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has become the icon
of these new predators.
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A giant dinosaur, with two-metre-long
spines rising over its back.
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It was unlike anything seen before.
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It was only in 2005,
when a complete upper jaw was found,
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that we could accurately reconstruct
this bizarre creature.
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With a skull almost two metres long,
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this dinosaur was a colossal 17 metres
from nose to tail.
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Four metres longer than T-Rex.
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The reign of the dinosaurs began
almost 250 million years ago,
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but this killer didn't appear until
a time known as the mid-Cretaceous.
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95 million years ago,
its home in North Africa
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was a desert surrounding
a vast system of rivers and swamps.
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The swamps are refuges
for many large dinosaurs,
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like the duck-billed Ouranosaurus.
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(SQUAWKS)
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(CALLING)
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They are also the hunting grounds
for a killer.
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(CALLING)
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(GROWLING)
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Spinosaurus,
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the biggest killer
ever to walk the earth.
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An 11-tonne colossus.
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However, for the time being,
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these Ouranosaurs
are off this killer's menu.
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Spinosaurus is part of a relatively
newly discovered family of dinosaurs.
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They've been found in South America
with Irritator,
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in Europe, there's Baryonyx,
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and Asia, Siamosaurus.
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But the last and biggest of all
came from North Africa:
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Spinosaurus itself.
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And studies of their bones and teeth
revealed something amazing.
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Spinosaurus is a predator,
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but one that hunts in water.
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Spinosaurus is unique.
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With long, narrow jaws and nostrils
set high on its head,
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its teeth were straight and conical,
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and it had a curious pattern
of holes in its snout,
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which give us a clue to how it hunted.
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These are Onchopristis,
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eight-metre-long giant sawfish.
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In 2008, a Spinosaurus skull
was put through a CT scanner.
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It revealed that the holes
and sinuses in the snout
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looked just like those of crocodiles.
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It's thought these contained
pressure sensors.
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Sensors that, like a crocodile,
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can detect the movement of prey.
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It can strike
without even seeing its victim.
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Anywhere else, this eight-metre Rugops
might be the top carnivore.
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But here, it is dwarfed by Spinosaurus,
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a predator that adapted to exploit
an environment so successfully
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it evolved into a 17-metre giant.
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Spinosaurus is the biggest
dinosaur predator ever discovered,
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but it wasn't the first giant killer.
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The first giant killer dinosaurs
appeared much earlier.
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They lived in the Jurassic period,
150 million years ago.
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One of the most iconic is Allosaurus,
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from the Morrison Formation
in North America.
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Yet it's only recently that
we have been able to work out
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how these predators hunted.
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(WIND HOWLING)
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(SNUFFLING)
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Allosaurus is the most common killer
in these lands.
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Nine metres long, with a battery
of saw blade-like teeth,
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Allosaurus is a formidable hunter.
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A lone Camptosaurus
should be an easy kill.
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Allosaurus teeth were serrated
front and back,
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perfectly evolved
for tearing through flesh.
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However, recent research has indicated
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that Allosaurus's bite was
surprisingly weak.
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Calculations suggested its bite
was less powerful than a lion's.
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So just how did this jurassic monster
hunt and kill?
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(SQUEAKS NERVOUSLY)
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Camptosaurus relies on its keen senses
to avoid predators.
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Allosaurus, on the other hand,
is a fast and powerful ambush hunter.
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(ROARING)
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(GROANING)
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(MOANING WEAKLY)
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(ROARING)
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Despite the apparent
weakness of its bite,
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Allosaurus did, in fact,
have a deadly killing method.
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Its skull could withstand a force
more than 15 times as great as its bite.
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This meant that Allosaurus
used its head like an axe,
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its strong neck muscles
driving its top jaw into its prey.
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With every impact, the serrated teeth
would tear through its prey's flesh...
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the victim dying through
a combination of shock and blood loss.
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(ROARING)
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Saurophaganax.
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At 12 metres, it is the biggest
carnivore in the region.
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(ROARING)
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(BOTH ROARING)
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One of the advantages of being so big
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is that stealing another's kill
is that much easier.
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With the rise of giant predators,
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and their spread
throughout the Jurassic world,
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smaller dinosaurs needed new strategies
if they were to survive.
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In recent years,
China has been the focus
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of some remarkable fossil discoveries.
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One extraordinary fossil hints
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how some may have avoided
these killer dinosaurs.
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It lived in the Jurassic forests
of China 154 million years ago.
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Hiding in these lush forests
is Epidexipteryx.
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This forest is home to many predators,
and being small makes it vulnerable.
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(DISTANT ROARING)
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This is Sinraptor.
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A small dinosaur like Epidexipteryx
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would be of no interest
to a seven-metre adult.
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But this is a juvenile.
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(ROARING)
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Being small does have its advantages.
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Everything we know about Epidexipteryx
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comes from an incredible fossil
first revealed in 2008.
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It showed an animal with a small skull
and large eye sockets
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and unusually long teeth,
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with toes suited to gripping branches
and very long arms and hands.
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It suggests that this was a dinosaur
well suited to living in the trees.
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The extraordinary
elongated third finger
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is another distinctive
feature of the group.
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With this
and its projecting front teeth,
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Epidexipteryx has the perfect tools
to hunt for insects.
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(INSECT BUZZING)
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Prey like this, which is
difficult to catch, is quite a prize.
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A prize that can attract
unwanted attention.
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Here it's another,
larger, Epidexipteryx.
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(SQUAWKING)
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(BOTH SQUAWKING)
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There is more to this extraordinary
creature than first meets the eye.
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The fossil has also revealed
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that it was covered
in short, simple feathers.
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Feathers that were likely
to have evolved for just one reason:
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to keep it warm.
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But there is one last striking feature:
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four long feathers on its tail.
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These feathers aren't like those
of modern birds.
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These are long and ribbon-like,
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almost certainly only for show.
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They're the earliest record
of ornamental feathers.
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In fact, the very name "Epidexipteryx"
means "display feather".
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(SQUAWKING)
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And they're among the most bird-like
of any dinosaur.
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Only in the trees can you be safe
from large predators like Sinraptor.
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Moving into the trees opened up
an entirely new world for dinosaurs.
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And it wasn't long
before killers followed.
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The most dramatic, found in 2000,
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lived in northeast China
around 120 million years ago,
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at the beginning of
the Cretaceous period.
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A dinosaur that took tree-living
to a whole new level.
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This is Xianglong.
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With prey like this,
predators were sure to follow.
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Microrapter.
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Microraptor is small, and well adapted
to chasing prey in the canopy.
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Xianglong, however, has a trick.
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This is a flying lizard.
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And the exquisite fossils of Microraptor
revealed a surprise.
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The feathers of this dinosaur
aren't for keeping warm, or for show.
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Their structure is plainly visible
from the fossils.
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They are very long, veined
and, most importantly,
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their shape creates
a perfect aerodynamic surface.
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And they aren't confined
to its forearms.
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Its legs, too, had long feathers.
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These feathers are designed
for one thing only:
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flight.
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Microraptor is a four-winged dinosaur
that took to the skies.
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But Microraptor isn't the only
flying monster here.
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Sinornithosaurus, more than capable
of stealing prey.
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But it has a bigger prize in mind.
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(GROANS)
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And Sinornithosaurus
has a deadly secret.
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In 2009, a study of Sinornithosaurus
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found distinctive grooves
along the length of its teeth.
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They resemble those of
the venomous Gila monster,
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the grooves of its teeth used
to deliver venom into its victim.
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The team even identified
what they thought
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was the location
of the venom sack in the fossil.
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It appeared Sinornithosaurus
could kill with poison.
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Having longer flight feathers
on both its arms and legs,
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Microraptor is by far the better glider.
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But with no ability to gain height,
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the only way is down.
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Microraptor's long feathers mean
it can barely walk, much less run.
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Sinornithosaurus has no such problem.
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On the forest floor,
the tables are turned.
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Microraptor has a fortunate escape.
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Killer dinosaurs dominated
the land, the trees,
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and had even taken to the air.
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But by the middle of the Cretaceous
period, things were changing.
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A new breed of killers was emerging.
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These were the famed Tyrannosaurs.
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Formidable hunter-killers that
swept aside almost all other predators.
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Carnivorous dinosaurs that remained
were forced to adapt,
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sometimes going to extreme lengths.
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One such group was
the bizarre Therizinosaurs.
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In 2009, the most complete skeleton
found so far was described.
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It lived in New Mexico
92 million years ago.
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(GROWLING)
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These swamps are home to Zunityrannus,
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a mid-sized Tyrannosaur.
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And they're also home
to this weird creature,
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Nothronychus.
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It's actually a close relative
of the Tyrannosaur,
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but with one major difference.
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Nothronychus has given up eating meat.
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(GROWLING)
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(ROARING)
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Therizinosaurs had been
a mystery for decades,
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known only from tantalising fragments.
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That all changed with
the discovery of Nothronychus.
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It gave us our clearest look
at this strange group of dinosaurs.
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It walked upright on short, stocky legs,
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it had wide hips and a long neck.
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Its teeth showed that
these weren't the teeth of a killer.
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Far from its ferocious
Tyrannosaur cousins,
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this pot-bellied dinosaur
had evolved into a strict vegetarian.
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But armed with viciously long claws
on its forearms,
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it was by no means defenceless.
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(GROWLING)
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By becoming a plant eater,
Nothronychus has easy access to food.
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(GROWLS)
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Nothronychus thrives here
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because it doesn't compete
with the Tyrannosaurs.
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But just because
you're not competing for food
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doesn't mean you're not seen as food.
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(GROWLING)
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Over the next few million years,
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Tyrannosaurs evolved,
getting bigger and more deadly.
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They developed
into the ultimate predators
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and dominated virtually
all of Asia and North America.
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The most famous of these
might be T-Rex,
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but it was just the last
in a long line of giant killers.
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75 million years ago,
North America was home
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to the original giant Tyrannosaur,
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Daspletosaurus.
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Its effectiveness as a killer
is clear from its anatomy.
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It's massive, with a huge, strong skull
and a powerful, muscular neck.
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Forward-facing eyes make
tracking moving prey easy.
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They've famously short arms,
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but with these giant Tyrannosaurs,
it's all about the bite.
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00:35:25,874 --> 00:35:27,459
Daspletosaurus,
246
00:35:30,087 --> 00:35:34,758
with a bite force unmatched
by any other dinosaur in the region.
247
00:35:40,597 --> 00:35:44,059
This is a killer in a
completely different league.
248
00:35:44,810 --> 00:35:46,436
(GROWLING)
249
00:35:52,693 --> 00:35:54,236
(ROARING)
250
00:36:07,166 --> 00:36:12,129
This group have congregated to
take advantage of an annual event.
251
00:36:22,139 --> 00:36:26,101
A vast herd of Centrosaurus
is on the move.
252
00:36:37,279 --> 00:36:41,408
Unwittingly, they're walking
towards almost certain death.
253
00:36:45,704 --> 00:36:48,040
In Dinosaur Provincial Park,
254
00:36:48,123 --> 00:36:50,375
thousands of bones have been discovered
255
00:36:50,459 --> 00:36:52,753
scattered across the same rock layer.
256
00:36:53,795 --> 00:36:57,466
They belong
to the horned dinosaur Centrosaurus.
257
00:36:58,675 --> 00:37:03,138
And they appear to be
the bone beds of vast killing fields,
258
00:37:03,472 --> 00:37:06,391
sites of wholesale slaughter.
259
00:37:23,575 --> 00:37:27,496
Seasonal monsoons drives
the Centrosaurs inland,
260
00:37:27,579 --> 00:37:29,748
away from coastal flooding.
261
00:37:35,170 --> 00:37:37,214
(THUNDER CLAPPING)
262
00:38:00,112 --> 00:38:02,030
(ROARING)
263
00:38:05,867 --> 00:38:08,704
Herding behaviour protects the many,
264
00:38:09,830 --> 00:38:11,873
but at the expense of the few.
265
00:38:35,731 --> 00:38:39,276
And things are about to get worse
for the Centrosaurs.
266
00:38:44,614 --> 00:38:47,075
With a flooded river ahead
267
00:38:47,784 --> 00:38:50,203
and the Daspletosaurus behind,
268
00:38:51,079 --> 00:38:53,832
the stage is now set for a massacre.
269
00:39:03,717 --> 00:39:07,554
But despite the rich pickings,
it's not the Daspletosaurus
270
00:39:07,637 --> 00:39:10,432
that are responsible
for the scale of the slaughter.
271
00:39:25,697 --> 00:39:29,409
There's an even more deadly killer
at work here.
272
00:40:17,332 --> 00:40:20,669
The real killer is the weather itself.
273
00:40:38,353 --> 00:40:41,356
Recent studies
of this dense bone bed indicate
274
00:40:41,440 --> 00:40:46,820
that 96% of the bones
are of a single species, Centrosaurus.
275
00:40:46,903 --> 00:40:50,866
And relatively few of the bones
display any bite marks.
276
00:40:51,408 --> 00:40:54,995
The fossil evidence suggests
that this was a mass drowning,
277
00:40:56,580 --> 00:40:59,791
the result of widespread
seasonal flooding.
278
00:41:01,543 --> 00:41:05,797
An event that we have seen repeated
in over 20 different sites.
279
00:41:14,347 --> 00:41:18,560
And when the waters recede,
new opportunities emerge.
280
00:41:22,606 --> 00:41:24,524
(SCREECHING)
281
00:41:32,574 --> 00:41:35,327
But even in the fight for rotting flesh,
282
00:41:35,410 --> 00:41:38,580
Daspletosaurus's authority is absolute.
283
00:41:45,754 --> 00:41:49,591
Tyrannosaurs' domination of the globe
might have been total
284
00:41:49,674 --> 00:41:54,387
had it not been for a strange quirk
in the arrangement of the continents.
285
00:41:56,348 --> 00:41:58,433
75 million years ago,
286
00:41:58,517 --> 00:42:01,645
the planet had a clear
north-south divide,
287
00:42:01,728 --> 00:42:05,148
with no physical link between
the parts of the globe.
288
00:42:05,357 --> 00:42:09,778
It meant the Tyrannosaurs couldn't
spread to the southern continents.
289
00:42:10,654 --> 00:42:14,032
Here, a different type of killer
reigned supreme.
290
00:42:17,494 --> 00:42:19,913
These were Abelisaurids.
291
00:42:23,291 --> 00:42:26,628
In the last 10 years,
Madagascar has provided
292
00:42:26,711 --> 00:42:29,923
the most comprehensive evidence
about these predators.
293
00:42:33,718 --> 00:42:38,557
70 million years ago,
Madagascar was already an island.
294
00:42:47,023 --> 00:42:48,441
In the Cretaceous period,
295
00:42:48,525 --> 00:42:51,736
Madagascar was subject
to devastating droughts.
296
00:43:00,829 --> 00:43:03,748
For big predators like Majungasaurus,
297
00:43:03,832 --> 00:43:07,210
scavenging is the only way to survive.
298
00:43:13,008 --> 00:43:15,385
(INSECTS BUZZING)
299
00:43:20,140 --> 00:43:23,935
We thought Majungasaurus
was the top predator here.
300
00:43:25,854 --> 00:43:30,066
But then in 2003,
some bones of a number of Majungasaurs
301
00:43:30,150 --> 00:43:33,194
were reported gouged with teeth marks.
302
00:43:36,114 --> 00:43:40,785
It appeared there was a bigger,
more brutal killer at large.
303
00:43:59,846 --> 00:44:01,222
(SQUAWKING)
304
00:44:23,370 --> 00:44:24,621
(GROWLING)
305
00:44:37,175 --> 00:44:38,468
(ROARING)
306
00:44:39,552 --> 00:44:44,516
A carcass will attract
every big predator for miles around.
307
00:44:55,860 --> 00:44:57,445
(GROWLING)
308
00:45:00,573 --> 00:45:02,450
A male Majungasaurus.
309
00:45:09,124 --> 00:45:12,127
It is more than capable
of challenging for the carcass.
310
00:45:18,383 --> 00:45:21,553
(ROARING)
311
00:46:28,203 --> 00:46:33,333
This fight is about more than just
winning the feeding rights to a carcass.
312
00:47:02,278 --> 00:47:05,657
When the bite marks
on the mauled Majungasaurus remains
313
00:47:05,740 --> 00:47:07,742
were studied more closely,
314
00:47:09,577 --> 00:47:11,871
the marks on the bones
were found to match
315
00:47:11,955 --> 00:47:15,166
the only large carnivore in the region,
316
00:47:17,460 --> 00:47:19,712
Majungasaurus itself.
317
00:47:21,798 --> 00:47:26,761
This is the first irrefutable evidence
of dinosaur cannibalism.
318
00:47:28,888 --> 00:47:33,017
It might seem shocking,
but it's a behaviour that clearly shows
319
00:47:33,101 --> 00:47:36,604
the most successful killers
will exploit any situation
320
00:47:36,688 --> 00:47:38,439
to their maximum advantage.
321
00:47:55,957 --> 00:47:59,502
Killer dinosaurs' ability to adapt
was exceptional.
322
00:47:59,794 --> 00:48:03,840
It meant they were able to colonise
every continent on the planet,
323
00:48:04,299 --> 00:48:07,010
continually evolving and changing.
324
00:48:07,468 --> 00:48:10,930
Their dominance of life on Earth
was absolute.
325
00:48:12,348 --> 00:48:14,392
Yet they were doomed.
326
00:48:21,316 --> 00:48:25,862
Their downfall was caused by
an asteroid smashing into the Earth.
327
00:48:28,823 --> 00:48:32,452
Travelling 20 times faster
than a speeding bullet,
328
00:48:32,911 --> 00:48:35,038
15 kilometres across,
329
00:48:35,246 --> 00:48:38,207
it slammed into the Gulf of Mexico.
330
00:48:42,045 --> 00:48:46,549
The impact released more energy
than a billion atomic bombs.
331
00:48:47,550 --> 00:48:53,640
The initial impact triggered wildfires,
massive earthquakes and tsunamis.
332
00:48:54,307 --> 00:48:59,187
But most devastating was the material
blasted high into the atmosphere.
333
00:49:01,773 --> 00:49:06,611
This shrouded the planet in a cloak
of darkness that lasted for months,
334
00:49:08,529 --> 00:49:10,239
cutting off sunlight.
335
00:49:10,323 --> 00:49:13,534
The Earth was thrown
into almost permanent night.
336
00:49:16,871 --> 00:49:18,915
Animals that survived the blast
337
00:49:18,998 --> 00:49:21,834
were now faced
with their greatest ordeal,
338
00:49:22,460 --> 00:49:26,005
as a devastating chain of events
was set in motion.
339
00:49:29,884 --> 00:49:33,388
Deprived of light, many plants died.
340
00:49:38,184 --> 00:49:40,895
Plant eaters are
the first to be affected.
341
00:49:45,775 --> 00:49:49,237
Fresh growth of plants offers
a glimmer of hope,
342
00:49:50,571 --> 00:49:53,282
allowing the smallest
to scratch out a living.
343
00:49:55,743 --> 00:49:59,080
But these aren't enough
to sustain anything for long.
344
00:50:01,165 --> 00:50:02,458
(SCREECHING)
345
00:50:12,176 --> 00:50:13,344
(SCREECHING)
346
00:50:24,939 --> 00:50:28,484
Scavengers initially have
an easier time of it.
347
00:50:36,367 --> 00:50:37,910
(SQUAWKING)
348
00:50:54,052 --> 00:50:56,596
But this surplus is an illusion.
349
00:51:03,561 --> 00:51:06,981
Once gone, scavengers will starve, too.
350
00:51:13,488 --> 00:51:18,117
The impact resulted in the collapse
of whole food chains.
351
00:51:18,201 --> 00:51:21,537
And the extinction
didn’t just affect dinosaurs.
352
00:51:23,039 --> 00:51:25,917
Virtually all life on Earth
was affected.
353
00:51:26,542 --> 00:51:30,588
More than 60% of all species
were wiped out.
354
00:51:32,632 --> 00:51:35,718
Yet the extinction wasn't a lottery.
355
00:51:35,802 --> 00:51:40,014
One factor more than any other
determined the dinosaurs' fate:
356
00:51:41,849 --> 00:51:43,392
size.
357
00:51:43,601 --> 00:51:48,606
On land, no animal weighing
more than 25 kilograms survived.
358
00:51:52,860 --> 00:51:56,948
There just isn't enough food
to sustain large animals.
359
00:52:01,994 --> 00:52:06,541
Ironically, it's the very thing
that makes dinosaurs so iconic
360
00:52:07,667 --> 00:52:09,627
that condemns them to extinction.