Planet Dinosaur: Ultimate Killers Page #3

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was exceptional.

It meant they were able to colonise

every continent on the planet,

continually evolving and changing.

Their dominance of life on Earth

was absolute.

Yet they were doomed.

Their downfall was caused by

an asteroid smashing into the Earth.

Travelling 20 times faster

than a speeding bullet,

1 5 kilometres across,

it slammed into the Gulf of Mexico.

The impact released more energy

than a billion atomic bombs.

The initial impact triggered wildfires,

massive earthquakes and tsunamis.

But most devastating was the material

blasted high into the atmosphere.

This shrouded the planet in a cloak

of darkness that lasted for months,

cutting off sunlight.

The Earth was thrown

into almost permanent night.

Animals that survived the blast

were now faced

with their greatest ordeal,

as a devastating chain of events

was set in motion.

Deprived of light, many plants died.

Plant eaters are

the first to be affected.

Fresh growth of plants offers

a glimmer of hope,

allowing the smallest

to scratch out a living.

But these aren't enough

to sustain anything for long.

(SCREECHING)

(SCREECHING)

Scavengers initially have

an easier time of it.

(SQUAWKING)

But this surplus is an illusion.

Once gone, scavengers will starve, too.

The impact resulted in the collapse

of whole food chains.

And the extinction

didn't just affect dinosaurs.

Virtually all life on Earth

was affected.

More than 60% of all species

were wiped out.

Yet the extinction wasn't a lottery.

One factor more than any other

determined the dinosaurs' fate:

size.

On land, no animal weighing

more than 25 kilograms survived.

There just isn't enough food

to sustain large animals.

Ironically, it's the very thing

that makes dinosaurs so iconic

that condemns them to extinction.

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