Name: 【TED-Ed】The ferocious predatory dinosaurs of Cretaceous Sahara - Nizar Ibrahim
Uploaded: 2017-07-05T04:34:49.000Z
Duration: 4 min 20 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

There are few places on Earth  less hospitable to life

100 million years ago, during a period known as the Mid-Cretaceous,

a gargantuan river system flowed across the region

The whole world at that time would look rather different to us.

The continents had yet to assume their current positions.

and fierce storms made life unpredictable.

and giant marine reptiles and sharks swam in warm seas.

Small mammals, our ancestors, lived quite literally in the shadow

which is what some call this region of what is now northern Africa,

In most ecosystems, it's lonely at the top of the food chain.

There usually isn't enough prey to sustain many predators.

Yet an incredible variety of aquatic prey species in the river-based ecosystem

may have allowed a large and diverse population of apex predators to coexist.

We know this thanks to a wealth of fossils we found in an area

Many of the predators we've discovered had head and body shapes

that made them uniquely adapted to hunt the different types and sizes

This allowed many Kem Kem predators to take full advantage

of the one abundant food source in this environment: fish.

This also allowed them  to avoid direct competition

with the predators going after land-loving animals.

Prey species in the river system had to contend with attacks from all sides,

Alanqa Saharica had a wingspan of up to nine meters,

and long slender jaws that helped it snatch fish

At least seven different types  of crocodile-like predators

including the roughly  ten-meter-long Elosuchus.

And multiple species of T-rex-sized carnivorous dinosaurs called theropods,

In the River of Giants, Spinosaurus was king.

This 15-meter-long dinosaur was even longer than T-rex,

It's two-meter-high sail warned other creatures of its fearsome size

and may have also been  used to attract mates.

Spinosaurus' long slender jaws were spiked with conical teeth,

perfect for swiftly clamping down on slippery aquatic prey.

This apex predator,  as well as its ecosystem,

is unparalleled in the history of life on Earth.

All that's left of these  fearsome predators are fossils.

About 93 million years ago,  sea levels rose,

submerging the Kem Kem region in a shallow sea.

wiped out the dinosaurs, pterosaurs, and many other groups of animals and plants,

That mass extinction paved the way for the rise of new kinds of birds,

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【TED-Ed】The ferocious predatory dinosaurs of Cretaceous Sahara - Nizar Ibrahim

literally

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