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Mosasaurus: In the coastal bayous and river channels bordering T. rex's territory, this massive marine reptile reigned. It was capable of swimming inland and could potentially ambush drinking dinosaurs from the water's edge.
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Imagine a world ruled by sea monsters. A
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planet where the oceans belonged to
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titans. This wasn't a movie script. It
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was our Earth 82 million years ago. And
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the king of this underwater realm, the
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Moasosaurus.
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Let's dive deep into the story of the
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real life sea king. A creature far more
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fascinating than any film could capture.
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Our story begins not in the deep ocean,
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but in a chro quarry near the city of
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Mr. in the Netherlands. Around the year
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1764,
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workers carving out stone stumbled upon
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something extraordinary, a massive
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fossilized skull armed with a terrifying
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set of teeth. They had no idea what they
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had found. Was it a whale? a giant
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crocodile. The local army surgeon, a man
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named Jean Leonard Hoffman, acquired the
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skull, believing it was a relic from the
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great biblical flood. He was an avid
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fossil collector, and this was the prize
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of his collection. But this incredible
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discovery soon became the center of a
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dramatic dispute. The owner of the land
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where the skull was found, a cannon
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named Gording, sued Hoffman to get it
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back and won. Gording then proudly
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displayed the magnificent skull in his
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home, but its fame had spread when
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French revolutionary forces besieged
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Mustri in 1794.
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The French were so determined to capture
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this scientific treasure that a reward
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of 600 bottles of wine was offered for
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its safe delivery. The skull was
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eventually found hidden in God's cellar
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and seized. It was taken to Paris as war
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booty where it remains to this day. It
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was in Paris that the skull finally met
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the man who would unlock its secrets.
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The great naturalist George's Cuvia, he
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studied the jaws and teeth, comparing
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them to modern animals. In 1808, Cuia
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concluded it was not a fish, whale, or
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crocodile. It was a giant extinct marine
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lizard, a new kind of animal science had
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never seen before. He named it the
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fossil animal from MRI. Later in 1822,
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it was given its official name,
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Moscasaurus Hoffman, meaning lizard of
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the Muse River, in honor of Hoffman, who
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first recognized its importance. This
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discovery was revolutionary. It provided
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concrete proof of extinction, the idea
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that entire species could vanish from
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the earth, which was a radical concept
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at the time. The Mosasaurus wasn't just
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a monster. It was a bombshell that
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changed our understanding of life's
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history. So, who was this creature that
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caused such a stir? The Mosasaurus
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wasn't a dinosaur. It was part of a
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group of marine reptiles called
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Mosasaurs, which were actually closely
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related to modern-day monitor lizards
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and snakes. Think of a Komodo dragon,
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but super sized with flippers instead of
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legs and a powerful tail fin. They
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evolved from land dwelling lizards that
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returned to the sea, undergoing a
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remarkable transformation over millions
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of years. Their legs became paddles,
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their bodies became streamlined, and
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they developed a second row of teeth on
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the roof of their mouths called tergoid
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teeth, which helped them grip struggling
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prey and pull it down their throats. By
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the late Cretaceous period, from about
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82 to 66 million years ago, the
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Mosasaurus had achieved something
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incredible. global domination. They were
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the undisputed apex predators of the
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world's oceans. Their fossils have been
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discovered on every single continent
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from the plains of North America to the
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frozen wastess of Antarctica. This tells
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us they were incredibly adaptable,
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thriving in a wide range of marine
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environments, from warm, shallow seas to
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cooler, deeper waters. Now, let's talk
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about size. The movies love to depict
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the mosasaurus as a leviathan capable of
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swallowing a great white shark hole and
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leaping out of the water to snatch
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dinosaurs from the shore. While that
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makes for great cinema, the reality is a
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little different but no less impressive.
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The largest known species, Mosasaurus
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Hoffman, one from Mosri reached lengths
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of about 56 ft, all around 17 to 18 m.
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To put that in perspective, that's
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longer than a school bus and
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significantly longer than a
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Tyrannosaurus Rex. It was one of the
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largest marine predators of all time, a
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true giant of the deep. But it wasn't
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the only one. The Mosasaur family was
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incredibly diverse with over 40
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different genre ranging from smaller 3-
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foot long species to the colossal
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Mosasaurus itself. What did a 56- ft
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long sea lizard eat? The short answer is
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pretty much anything it wanted.
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Mosasaurus was a versatile and
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opportunistic hunter. Fossil evidence,
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including stomach contents and bite
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marks on other fossils, gives us a clear
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picture of their diet. They devoured
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large fish, sharks, and giant sea
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turtles, whose shells they could crush
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with their powerful jaws. They also
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prayed on ammonites, the large coiled
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shell relatives of modern squids. And
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yes, they were cannibals. We have found
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fossils of smaller mosasaurs with bite
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marks that perfectly match the teeth of
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larger mosasaurus individuals. In their
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world, it was eat or be eaten. Their
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hunting technique was likely one of
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ambush and brute force. They weren't
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necessarily the fastest swimmers over
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long distances, but they could generate
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incredible bursts of speed. Using their
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powerful fruit-like tail, they would
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launch themselves at prey with
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devastating force. Their skulls were
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also uniquely designed. Unlike most
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reptiles, they had a flexible
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doublehinged jaw, much like a snakes,
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which allowed them to open their mouths
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incredibly wide and swallow very large
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prey hole. They were the ultimate
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oceanic terror. For a long time, we
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thought of mosasaurs as purely marine
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animals confined to the world's oceans
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and saltwater seas. But science is
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always full of surprises. In a
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groundbreaking study published in
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January 2026,
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researchers announced a stunning
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discovery. They found evidence that
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Samosasaur species had actually adapted
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to live in freshwater environments.
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Fossils found in ancient river systems
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showed that these particular mosasaurs
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were thriving in rivers and estuaries
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hunting alongside giant freshwater
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crocodiles and other riverini predators.
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This completely changed our view of
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their ecology. It showed they were even
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more adaptable than we ever imagined.
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capable of conquering not just the seas
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but the rivers too. They truly were
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masters of the aquatic world. So if they
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were so successful, so dominant, so
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widespread, where did they all go? The
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reign of the sea kings ended not with a
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whimper, but with a bang, a
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catastrophic,
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world altering bang. 66 million years
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ago, a massive asteroid estimated to be
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6 mi wide slammed into the planet in
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what is now the Yucatan Peninsula in
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Mexico. The impact was cataclysmic. It
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triggered global earthquakes, volcanic
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eruptions, and mega tsunamis that swept
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across the continents. A thick cloud of
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dust and soot was thrown into the
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atmosphere, blocking out the sun for
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months, maybe even years. This event,
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known as the Cretaceous Spale gene
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extinction event, is famous for wiping
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out the non-avian dinosaurs. But its
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effect on the oceans was just as
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devastating. The lack of sunlight caused
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a total collapse of marine ecosystems.
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The phytoer plankton, the tiny organisms
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at the very base of the food chain, died
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off. This meant the small animals that
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fed on them like ammonites and small
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fish also starved and disappeared. For a
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massive apex predator like Mosasaurus,
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this was a death sentence. Their entire
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food source vanished from beneath them.
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You can't be a 56- ft long carnivore if
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there's nothing to eat. Within a
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geologic blink of an eye, the mighty
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Mosasaurs, who had ruled the oceans for
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millions of years, were gone. They
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vanished from the fossil record, never
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to return. The age of the great marine
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reptiles was over, paving the way for
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the rise of a new group of oceanic
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rulers, the mammals, which would
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eventually evolve into the whales and
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dolphins we know today. And what of the
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fossil that started it all? That famous
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skull, the one bought for 600 bottles of
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wine, remains a masterpiece of
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paleontological history. You can see it
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today at the National Museum of Natural
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History in Paris, a testament to a lost
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world. From its humble discovery in a
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Dutch quarry to its dramatic journey to
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Paris and its central role in changing
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science, the story of the Mosasaurus is
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a powerful reminder. It teaches us that
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our planet as history is filled with
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creatures more inspiring than any myth
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or legend. The most terrifying and most
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magnificent monsters aren't born from
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human imagination. They are born of
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time, tide, and the incredible,
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everchanging story of life on Earth.
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Thanks for joining us on this journey
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back in time. If you enjoyed this deep
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dive into the world of the Mercasaurus,
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don't forget to like, subscribe, and hit
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that notification bell so you don't miss
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our next adventure into the prehistoric
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world. See you next time.
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