6 Sea Monsters You Should Be Glad Are Extinct

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1. Helicoproin existed 290 million years ago. They had 360 degree spiraling serrated teeth.

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Helicoproin = Texas Chainsaw Massacre: Ocean Edition.

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2. Dunkleosteus existed 358 million years ago. They were made of armored plating and their teeth were sharp bony plates.

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Dunkleosteus size comparison.

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This is what it'd look like if you were in a sea cage and a Dunkleosteus swam by.

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3. Mosasaur existed more than 66 million years ago. They were incredibly fast despite their 13 feet of length.

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Mosasaur: "She tastes like chicken".

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4. Giant Crabs existed more than 50 million years ago and had a hammer-proof body and could move faster than Bdoubled.

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Here's how the Giant Crab looks in a video game.

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5. Plesiosaurus went extinct 66 million years ago despite being very adept at survival.

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Would you want to swim with a Plesiosaurus? I'm afraid of seaweed, so no thanks.

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6. Megaladon were the biggest sharks to ever roam the ocean, and went extinct only 23 million years ago.

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Megaladon teeth indicate just how big the shark really was.