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The most fearsome predator
of the Jurassic

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is watching his prey

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Peering through the water,

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the carnivore
fixes on his unwary victim,

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waiting for the perfect moment
to strike

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Under these azure waters
lies the future continent of Europe,

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but now,
in the late Jurassic period,

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all that exists here
are a few scattered islands

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The break-up of the old continents

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has pushed up the ocean floor
and raised sea levels,

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flooding the lowlands
and creating vast shallow seas

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Here, dinosaurs do NOT rule

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Instead, giant marine reptiles
have evolved,

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perfectly adapted to life
in these beautiful waters

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All of them are air-breathers,
like this eight-tonne Cryptoclidus

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On the land,
they are cumbersome hulks,

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but in water, they are transformed

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All sea reptiles once lived on land,

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but 75 million years ago,

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their ancestors took to the water

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and their legs became flippers

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They share this shallow sea

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with other strange Jurassic
creatures, like the ammonites,

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that snare small prey
with their tentacles

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These rich, sunlit waters

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are on the northern edge
of the ancient Tethys Ocean -

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the sea that separates
the Earth's two continents,

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one in the north
and one in the south

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Once a year, they are the stage

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for a remarkable natural drama

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It starts with
a single pregnant Ophthalmosaurus,

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followed by hundreds more
of her kind

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All are gathering here
from deeper water to give birth

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These are the oldest
of marine reptiles

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and most completely adapted
to aquatic life,

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with streamlined fish-like bodies

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Most other marine reptiles,

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like Cryptoclidus,
use all four flippers

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to chase the blizzards of fish
through the water

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Flapping like underwater wings,
the flippers can be used separately

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to give them huge manoeuvrability,

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or together,
for sudden bursts of speed

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This unique method of locomotion

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is destined to disappear
from the ocean

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at the end of the age
of the dinosaurs

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The animals
on the small islands above

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also depend on the sea's bounty
for their survival

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Among the jagged rocks
live a colony of flying reptiles

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These sea pterosaurs
are called Rhamphorhynchus

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They have evolved a way
of catching fish

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without getting their wings wet

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Their beaks skim through the water,

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grabbing anything in their path

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The teeth of these flying reptiles
may look bizarre,

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but they are ideal for snatching
slippery fish from the water

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However, swallowing their catch
is a different matter

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(Harsh squawking)

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(Low growling)

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The Ophthalmosaurus
are starting to give birth

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Most sea reptiles lay eggs on land,
but not Ophthalmosaurus

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They give birth to live young

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This frees them from the need
to crawl out of the water,

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and has allowed them to evolve
their fish-like shapes

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A female has two to five pups,

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but since they are air-breathers,

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the young must be born tail first,

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or they would drown
before they escaped from the mother

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The newborn pups
have just a few seconds

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to reach the surface
and take their first breath

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As soon as they are born,
the pups are vulnerable

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These waters are full of predators

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Even adult Ophthalmosaurus
will eat the offspring of others

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to increase the chance of survival
for their own pups

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The only real safety
is amongst the crags of coral

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Birth is a dangerous time
for the mothers, too

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This female is trying desperately

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to expel her unborn offspring

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Fighting for air,
she stays near the surface

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Her struggles are a lure to sharks

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These predators have acute hearing,

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and the sound of splashing
betrays an animal in distress

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As perfectly evolved
killing machines,

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sharks patrolled the oceans

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long before
marine reptiles appeared

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After 20 minutes,
her exertions are exhausting her

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She is having
to breathe more frequently

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The sharks start to move in closer

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Suddenly, something lurking
in the gloom scatters the sharks

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Liopleurodon - at 150 tonnes,

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it is the largest
and most powerful carnivore

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ever to live on the planet

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This male measures
a colossal 25 metres,

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and is big even for his kind

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His size means he is probably
over 100 years old

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He, too, detected the mother's
distress from a distance

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Liopleurodon
has a directional sense of smell-

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two chambers in his nose

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work in the same way
as a pair of ears -

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pinpointing the source of a smell-

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a sophisticated tracking device,

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steering the largest
carnivorous jaws ever known

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Each one of Liopleurodon's four
flippers is over three metres long,

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giving him enough power

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to guide his huge bulk effortlessly
through the water

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By now,
the coral reefs around the islands

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are full of baby Ophthalmosaurus

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This intricate network of caves
is their refuge,

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a safe haven from which they can
start to learn about their world

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Baby Ophthalmosaurus
have prominent teeth,

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allowing them to cope
with the tough prey

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they find among the coral

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But this little male
has yet to learn

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that ammonite shells
are too tough for him

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Above the sea,
food is less plentiful

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A lonely dinosaur has been forced
to swim between the islands

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in search of a meal

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With huge marine predators
in the water,

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this is a dangerous journey

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Large dinosaurs are rare here,

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and at five metres
from nose to tail,

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Eustreptospondylus is the biggest

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They are primarily scavengers,

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combing the beaches
for dead animals,

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but on such small islands,

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they are always under pressure
to find more carrion

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But another scavenger
has got here first

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This Eustreptospondylus

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is picking the last rotten strips
of flesh off a dead turtle

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But even these decaying remains

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are enough to trigger
a confrontation

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(Growling)

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Neither will risk an injury

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and in the end,
it is the loudest roar that wins

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(Fierce roar)

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The only food supply here that is
not from the sea is the insects

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Bark beetles infest the trees here

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They represent
a tantalising feast of protein

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just under the surface

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This tempts a young Rhamphorhynchus
to probe for insect larvae,

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but this is not really a job
his beak is evolved to cope with

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Now two weeks old,

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the young Ophthalmosaurus
are growing fast on a seafood diet,

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but they are still at risk

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especially from shark attack

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A head of coral provides
a temporary refuge for this pup

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His pursuer has a deadly advantage -

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he does not have to return
to the surface to breathe

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and has only to wait
until the pup needs air

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But the little reptile
has one thing on his side

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speed

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Safe
until he needs to breathe again

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Having a lungful of air

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presents marine reptiles
with a buoyancy problem

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Cryptoclidus has found one solution

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He is not searching for food
in the sand

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He is after pebbles and grit

157
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Sieving off the fine grains,

158
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he retains the larger stones
in his stomach for ballast,

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which weighs him down and
counteracts the air in his lungs

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The land represents safety
for the Cryptoclidus -

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they have come up
onto the rock ledges to rest,

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and also to be out of reach
of Liopleurodon

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Darkness does not bring peace
in the restless sea

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Billions of microscopic creatures

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rise up from the depths
as the light fails,

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and shoals of fish
surge into life to pursue them

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Ophthalmosaurus adults
are masters of hunting at night

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Most have left for deeper waters,

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but a few remain to take advantage
of the plenty here

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With their enormous
light-sensitive eyes,

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they pick out squid in the gloom

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Their long toothless snouts
are streamlined weapons,

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making it easy for them
to snap up fast-moving prey

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00:18:11,631 --> 00:18:13,588
With the approaching full moon,

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strange-looking visitors

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gather on the shoreline
in their thousands

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00:18:19,831 --> 00:18:23,791
These are horseshoe crabs -
ancient creatures

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who originated 150 million years
before the Jurassic

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On a high tide,
the females struggle up the beach

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and each lay as many as 18,000 eggs,

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which the males
compete to fertilise

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This strategy has served them well

183
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since before the dinosaurs appeared,

184
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and will do so for at least
another 150 million years to come

185
00:19:22,151 --> 00:19:26,464
Early morning, and the horseshoe
crabs cause a feeding frenzy

186
00:19:29,045 --> 00:19:32,083
Every year, the Rhamphorhynchus
come to this beach

187
00:19:32,165 --> 00:19:34,043
to gather up the eggs,

188
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while the last few crabs
struggle back into the water

189
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The nutritious eggs
are an easy meal for these reptiles

190
00:19:51,645 --> 00:19:55,605
But nature seldom offers anything
free of risk

191
00:19:58,525 --> 00:20:01,677
(Low growling)

192
00:20:23,205 --> 00:20:26,164
(Squawking)

193
00:21:10,005 --> 00:21:11,962
A month later

194
00:21:12,045 --> 00:21:16,005
Tiny horseshoe crabs start
to work their way out of the eggs

195
00:21:16,085 --> 00:21:19,920
The high tide that brought
the females up the beach

196
00:21:20,005 --> 00:21:24,079
now sweeps their offspring
back into the sea

197
00:21:41,165 --> 00:21:44,954
For the pups, their secure life
around the reef

198
00:21:45,045 --> 00:21:47,844
is coming to an end

199
00:21:47,925 --> 00:21:50,997
In a few weeks,
they'll be big enough

200
00:21:51,085 --> 00:21:53,395
for life in the open oceans

201
00:22:02,205 --> 00:22:04,561
The first signs are when,
like adults,

202
00:22:04,645 --> 00:22:09,083
they show the skills
to hunt fish in open waters

203
00:22:19,525 --> 00:22:21,994
This is not without risk

204
00:22:22,085 --> 00:22:24,998
The sharks are still a danger

205
00:22:25,085 --> 00:22:29,682
One day, these will be the
most feared predators in the sea,

206
00:22:29,765 --> 00:22:32,200
but in these Jurassic waters,

207
00:22:32,285 --> 00:22:34,720
they themselves are prey

208
00:22:35,885 --> 00:22:39,845
The Liopleurodon
is an expert at ambush

209
00:22:39,925 --> 00:22:42,724
He takes one giant gulp of air,

210
00:22:42,805 --> 00:22:45,764
then descends to hide in the depths

211
00:22:46,965 --> 00:22:50,925
There, he can hold his breath
for over an hour

212
00:22:52,165 --> 00:22:55,124
And Liopleurodon is a shark-eater

213
00:23:05,285 --> 00:23:09,245
Unexpectedly, a female Liopleurodon
arrives on the scene

214
00:23:09,325 --> 00:23:12,397
This, the bull will not tolerate

215
00:23:19,448 --> 00:23:23,365
Liopleurodon
are fiercely territorial

216
00:23:23,448 --> 00:23:27,408
and confrontations
almost always end in violence

217
00:23:50,666 --> 00:23:53,625
The female
is forced to leave the area

218
00:23:53,706 --> 00:23:55,937
Her flipper has been badly ripped

219
00:23:56,026 --> 00:23:58,621
by the male's tusk-like teeth,

220
00:23:58,706 --> 00:24:03,019
attracting sharks
that follow her trail of blood

221
00:24:14,767 --> 00:24:17,637
It is four months
since the pups were born

222
00:24:17,727 --> 00:24:19,684
and they're ready to leave,

223
00:24:19,767 --> 00:24:22,760
but they are facing
one of the greatest hazards

224
00:24:22,847 --> 00:24:24,804
of this cruel sea

225
00:24:24,887 --> 00:24:27,686
These islands are regularly ravaged

226
00:24:27,767 --> 00:24:31,522
by violent tropical storms
that are strong enough

227
00:24:31,607 --> 00:24:34,998
to tear up the shallow sea beds,
smash corals

228
00:24:35,087 --> 00:24:37,647
and kill thousands
of marine animals

229
00:25:22,151 --> 00:25:25,701
The storm has had its victims

230
00:25:25,791 --> 00:25:29,182
It was not just these
delicate-boned Rhamphorhynchus

231
00:25:29,271 --> 00:25:33,231
that were broken
in the 100-mph winds

232
00:25:35,471 --> 00:25:40,421
the old Liopleurodon,
disorientated in the murky waters,

233
00:25:40,511 --> 00:25:44,221
has ended up
stranded on an island beach

234
00:25:53,951 --> 00:25:57,911
As the beachcombers start to gather,
they are wary

235
00:25:57,991 --> 00:26:00,870
While the giant is still alive,

236
00:26:00,951 --> 00:26:03,705
his enormous jaws are lethal

237
00:26:11,231 --> 00:26:14,668
But they can afford
to bide their time

238
00:26:21,951 --> 00:26:24,785
The carnivore's own 150-tonne body

239
00:26:24,871 --> 00:26:27,227
is slowly suffocating him

240
00:26:42,751 --> 00:26:46,506
The Liopleurodon's life
has now ebbed away

241
00:26:46,591 --> 00:26:50,790
The mightiest carnivore
the world has ever seen

242
00:26:50,871 --> 00:26:53,261
is no more than a banquet

243
00:26:53,351 --> 00:26:56,105
for a group of lucky scavengers

244
00:27:05,562 --> 00:27:11,274
The Jurassic is a golden period
for giant marine reptiles

245
00:27:14,522 --> 00:27:16,957
It will be another 90 million years

246
00:27:17,042 --> 00:27:19,432
before they vanish from the oceans,

247
00:27:19,522 --> 00:27:24,199
along with the extinction
of the dinosaurs on land

248
00:27:34,057 --> 00:27:38,927
Most of the Ophthalmosaurus pups
have survived the storm

249
00:27:39,017 --> 00:27:42,169
and now face life in the open sea

250
00:27:42,257 --> 00:27:46,297
One day, the females will return,
and when they do,

251
00:27:46,377 --> 00:27:50,337
they will be carrying
the next generation

252
00:28:06,017 --> 00:28:09,977
Marine reptiles were one of
the glories of this ancient time -

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even though turtles
are the only ones left today

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Another group of reptiles shared the
dinosaurs' world - the pterosaurs

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As we shall see in the next episode,
they were just as spectacular