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{\an8}Dinosaurs ruled the planet
for over 150 million years.
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They occupied almost every corner
of the globe
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and came in almost
every shape and size imaginable.
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Some were truly extraordinary.
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We now know that T. rex was
a powerful swimmer...
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Velociraptors were cunning,
feathered hunters,
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and that some dinosaurs had
the most bizarre behavior.
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But new discoveries
are being made almost every day
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that tell us more about life
on this planet 66 million years ago.
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This time on Prehistoric Planet,
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we reveal new animals
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and new insight
into their quest to find a partner,
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the challenges faced by raising a family,
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and their titanic battles.
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Journey to a time
when nature put on its greatest show.
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This is Prehistoric Planet 2.
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The ocean.
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The largest habitat
on the prehistoric planet...
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and home to one of the biggest predators
that has ever lived...
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a giant mosasaur.
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But not all mosasaurs are
ferocious 50-foot-long monsters.
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Taking refuge in the reef
is Phosphorosaurus.
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She too is a mosasaur.
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One of the smallest,
at less than ten feet long.
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She spends the daylight hours
hiding from danger.
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But once or twice an hour, she has to
dart to the surface to grab a breath.
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Like all of her kind,
she is air-breathing.
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She's dwarfed by the biggest mosasaurs.
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But she too is a deadly predator...
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and she doesn't always hide
in the shadows.
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When the time is right,
she becomes a hunter.
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And that time is when the sun sets.
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As darkness falls,
her underwater world transforms.
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Now, billions of creatures will begin
to rise from the depths
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to feed near the surface.
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The largest mass migration on Earth occurs
in almost total darkness
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and can only be seen
with special night-vision cameras.
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The most spectacular of these nighttime
visitors are a type of lantern fish.
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Their faint, eerie light is produced by
a chemical reaction inside their bodies.
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A flash of this bioluminescence
can be used to confuse predators.
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And when seen from below,
the glow enables them to blend with
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and hide against
the ocean's moonlit surface.
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But they can't hide from Phosphorosaurus.
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For her size,
her eyes are the largest of any mosasaur...
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allowing her to see through the illusion
and pick out her prey.
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By the time dawn arrives,
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the migrating shoal has sunk once more
to the depths.
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And Phosphorosaurus too must return
to her daytime hiding place.
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The biggest mosasaurs are back
on the prowl.
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She will have to wait till nightfall
before it's safe to hunt again.
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By day, the prehistoric ocean
provides opportunities
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for a very different type of hunter.
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In the warm,
shallow seas of North America,
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fish numbers can almost match
the nocturnal lantern fish shoal.
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And they are a magnet
for six-foot-long Hesperornis.
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Hesperornis may be unable to fly,
but it's superbly adapted for ocean life.
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Large, powerful feet propel it
with great agility.
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There's no escape for any unfortunate fish
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once it's caught by this beak
full of needle-sharp teeth.
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The Hesperornis don't have the shoal
to themselves for long.
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Xiphactinus, known as X-fish.
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The feeding opportunity soon attracts them
in large numbers.
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At over 17-feet long, they are one of
the largest and fastest fish in the ocean.
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With its huge mouth, Xiphactinus can
scoop up several fish at once
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and has even been known to swallow prey
half its size whole.
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At first, there is plenty for everyone.
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But as fish numbers dwindle,
the X-fish turn their attention elsewhere.
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Predator is about to become prey.
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The Hesperornis have only one option:
to swim for their lives.
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Xiphactinus is faster.
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Hesperornis is more agile.
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But in the eyes of an X-fish,
anything is on the menu...
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even their own kind.
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Within minutes,
the banquet is all but gone...
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and the predators move on.
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Danger in the ocean
doesn't only come from deadly hunters.
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It could come from the sea itself.
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Here, around the islands
of prehistoric Europe,
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it's the power of the tide
that creates challenges for life.
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Especially for the tiniest creatures.
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These are ammonite eggs.
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Thousands of them.
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They have been swept inshore...
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to rock pools.
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Here, they have the chance
to develop free from danger.
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The eggs are tiny,
only a fraction of an inch each.
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Now it's time for the young within
to break free.
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They move by jet propulsion.
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But mastering new swimming skills
is not easy.
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Until now,
these pools have provided a nursery.
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But as the tide retreats,
they become isolated.
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Others can make their escape.
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But for the helpless ammonites,
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their nursery can quickly become
a deadly trap.
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Under the midday sun,
the water in the pool starts to evaporate.
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If it dries out completely,
they will all die.
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But everything is not lost.
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Baby ammonites can do
something remarkable.
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Each makes its own bid for freedom,
forcing them together.
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The combined effort means
they effectively move as one.
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Each is carried along
on this tiny living tide,
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pushed over the bare rock by those behind...
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eventually escaping to deeper water.
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Now they wait for the rising tide.
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But not everyone escapes.
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Countless are left stranded...
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food for scavengers,
like these baby Pyroraptors.
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The rest are carried by powerful currents
many miles from land.
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Even as far as this,
the very heart of the Pacific Ocean.
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These enormous atolls
and the lagoons at their center
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provide the only shelter
for thousands of miles.
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In this rare place, Tuarangisaurus,
a kind of elasmosaur, finds safety.
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But outside these shallows,
it's a different story.
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Each day, the elasmosaurs must venture
into deeper water.
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Canyons in the atoll walls lead
from the shallows to rich feeding grounds.
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This deep water attracts
not just the hungry elasmosaurs
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but the predators that hunt them.
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The biggest in the ocean.
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50-foot-long Mosasaurus.
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Nutrients driven up from the ocean floor
ensure a plentiful supply of fish.
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Streamlined bodies
and four powerful flippers
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give elasmosaurs great maneuverability.
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But their daily feeding forays make
their movements predictable
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for an intelligent and patient hunter.
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Mosasaurus is an ambush predator.
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This enormous animal uses its huge tail
to accelerate with astonishing speed.
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This time, unlucky.
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In fact, most hunts fail.
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But with so many elasmosaurs living here,
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it's not long
before there is another opportunity.
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Camouflaged against the dark canyon floor,
the mosasaur can approach unseen...
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waiting for a young,
inexperienced individual.
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The ideal victim.
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Mosasaurus can strike their prey
with such force
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that the impact alone can kill.
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It's an attack so swift, the elasmosaur
almost certainly never saw it coming.
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Life in the ocean can be dangerous,
not only because of giants.
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Of the baby ammonites
that escaped the rock pools,
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less than one in a hundred has survived
several months at sea.
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But these few have been
particularly lucky.
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Ocean currents have carried them
to an ideal place to live:
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seagrass beds off the coast of Europe.
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Here, shoals of ammonites occur
in a surprising variety of sizes...
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and shapes.
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This strange,
six-foot-long giant is Baculites,
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which feeds near the seafloor.
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And almost matching it in size,
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Diplomoceras,
shaped like a giant paper clip.
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They all flourish here,
thanks to an abundance of food.
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Plankton. Small crustaceans.
Some even eat fish.
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These hatchlings are beginning to acquire
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the extraordinary shape they will have
when they are mature.
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The protruding spiral identifies them
as young Nostoceras.
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These are adult Nostoceras.
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They favor the seafloor in deeper waters.
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Ammonites have been thriving
in these prehistoric oceans
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for almost 400 million years.
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There are thousands of species.
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They are one of the most successful groups
of animals to have ever lived...
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flourishing in the warm, temperate seas
and even the coldest waters at the poles.
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Like here, in the frozen sea
around the Antarctic.
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After a winter of near-total darkness,
the low sun is beginning to melt the ice...
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making it accessible once more
for a giant seasonal visitor.
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Morturneria, a strange type of elasmosaur.
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They are warm-blooded,
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with a thick layer of blubber
which conserves the heat in their body.
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They're one of the world's most secretive
and elusive animals.
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This pod has migrated nearly 2,000 miles
from South America
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to arrive here in time for spring.
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It's the first time this year's calves
will have encountered sea ice.
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It can be dangerous
for an air-breathing reptile.
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They can only grab a breath of air
where there are gaps in the ice.
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Adults must navigate carefully
to find them,
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and the youngsters must stay close.
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These cold waters are an excellent habitat
for this giant's favorite food.
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Polar mud full of small creatures.
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There can be hundreds of tiny animals
in every square foot of seafloor.
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Separating what's edible
from the sticky mud is a challenge.
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But they have a neat solution.
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Scooping up a mouthful,
they partially close their jaws,
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creating a giant sieve
to filter out the food.
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These are the only animals
to have evolved teeth to feed in this way.
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The Morturneria will feed here all summer,
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until the water ices over again
in the polar winter.
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In warmer waters,
they will face other challenges.
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But the most resourceful animals
will always find opportunities
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in the vast oceans
of the prehistoric planet.
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The lands of the prehistoric planet
were ruled by the dinosaurs.
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But the seas were dominated
by a very different group of reptiles:
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the mosasaurs.
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And this is the skull of one of them.
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Mosasaurs were seagoing lizards.
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{\an8}Think of a giant, swimming,
whale-sized Komodo dragon.
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Tapered snout, rough skin,
four fins instead of normal limbs
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and a long tail that would look
a lot like a shark tail but upside down.
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That's basically a mosasaur.
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The largest was Mosasaurus hoffmanni.
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It was an ambush predator.
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But what was the secret of its success?
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{\an8}They can move from just still,
not moving at all
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{\an8}to incredible speeds
right before your eyes.
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In the modern world, we see
this ability in reptiles like crocodiles.
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Their muscles can deliver short bursts
of tremendous power.
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Mosasaurus, given that they're reptiles,
given that they're lizards,
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probably had similar capabilities
in their muscles.
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They also had another adaptation
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that could increase
the element of surprise.
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One of the tricky things about swimming is
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you need a special kind of dynamic
to get out of the gate quickly,
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to do the equivalent of a sprinter's start
from the blocks.
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And one of the best ways of doing that is
to bend yourself into a C-shape
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and then push off of the water
with the side of your body.
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Fish today use this technique.
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Known as a C-start,
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{\an8}it allows them to accelerate from
a standstill to full speed in an instant.
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{\an8}Mosasaurs likely were able to do
something very similar,
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but of course at a much grander scale.
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So, exactly how fast could
a giant like Mosasaurus hoffmanni swim?
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To find out, the Prehistoric Planet team
commissioned a unique scientific study.
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Until recently,
no one had really attempted to estimate
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these kinds of performance values
in detail.
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Our work is one of the first attempts
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to really put numbers to the abilities
of these animals.
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And the results we got from that
are really pretty stunning.
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{\an8}The team ran the calculations four times
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{\an8}to ensure they were correct.
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{\an8}All four of the different trials
came to the same overall conclusion.
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These animals were able to generate
massive accelerations.
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This mosasaur, it could probably
clear 75% of its body length
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in one single second.
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That means, if that mosasaur is
17 meters away from you,
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in one second, it will be 75% closer.
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And in the second second,
it would have surpassed you
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and probably eaten you along the way.
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Being hit by a Mosasaurus would be
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a bit like being hit
by a full-size semitruck.
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Just the impact of the animal alone,
much less the bite that would follow,
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would kill a lot of its prey instantly.
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00:34:52,426 --> 00:34:54,928
Mosasaurs could reach 30 miles an hour
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in as little as one second.
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This is what makes them, arguably,
the ultimate marine predator of all time.