• Weird Nature

11 Borderline Horrifying Prehistoric Creatures That Lived 500 Million Years Ago

List RulesVote up the creatures you're kind of glad went extinct.

More than 500 million years ago, a frozen, hostile Earth awakened. Scary prehistoric creatures began changing at breathtaking speed. This time of remarkable change is known to the scientific community as the Cambrian explosion.

So, what is the Cambrian explosion? In short, it is a cataclysmic happening that allegedly forced the microorganisms that used to rule the world into a state of rapid evolution. This solitary event is a topic of great debate for scientists far and wide, mainly because it poses some challenges to the theory of evolution itself. Did the Cambrian explosion even happen at all? And if it did, how did it affect the animals that survived? These are just a few of the looming questions that surround the theoretical explosion.

Creatures from before the Cambrian explosion predate all recognizable early life, including dinosaurs. These beings were almost alien in appearance, with backwards facing heads, protruding limbs with claws, and some of the craziest eyeballs known to man. Most of them do not exist today. Those that do are distant relatives, barely recognizable to their initial forms. Here’s a look at some of the most terrifying and intriguing beings from before this mystifying time period.

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    Hallucigenia Had Teeth Extending Down Its Throat

    Photo: Jose manuel canete / Wikimedia Commons / CC-BY-SA 4.0

    Hallucigenia was a Cambrian worm with an elongated spiky body, legs, and needle-sized teeth that protruded past the jaw line and went all the way down its throat. Its fossil sports a devilish grin that helped scientist to identify its head from its tail. Research suggests that this baffling creature sucked food up into its toothy, o-shaped mouth like a vacuum cleaner. Despite its unusual appearance, it shares ties with modern-day spiders and cycloneuralia worms.

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    Anomalocaris Was A Terrifying Apex Predator

    The Anomalocaris was a giant for its time. Reaching lengths of over three feet, this mesmerizing maritime creature resembled a humongous shrimp. Most of its body was made of its head alone. Its bone crushing" teeth" were comprised of serrated prongs so long the creature was unable to completely close its own mouth.

    With arms covered in spikes and eyes sporting 16,000 individual lenses, the Anomalocaris is believed to have been the most vicious predator in the sea. Some scientists claim that it fed on trilobites, leaving W-shaped indentations in their hard-shelled bodies that would last in the fossil record for hundreds of millions of years.

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    Opabina Had Five Eyes And A Backwards Head

    The now extinct Opabina was a curious creature. Sporting five gaping eyes and a backwards head, this pre-Cambrian animal is believed to have waited for its food on the ocean floor. Since its mouth was positioned beneath its head, it had to rely on its proboscis, a trunk-like snout, in order to eat. Its jointed appendages and the singular claw extending out from its head made the Opabina one bloodcurdling sight to behold.

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    Fuxianhuiid Had Several Limbs Growing Out Of Its Head

    You can't discuss pre-Cambrian animals without paying tribute to the Fuxianhuiid. This ancient variation of an arthropod had quite a unique look. It had limbs that protruded from the bottom of its head, used to filter and then shovel food into its mouth in a process known as detritus sweep-feeding. And something even crazier was found extended out past its head: its nervous system. This phenomenon is called a post-cephalic nervous system, and Fuxianhuiid is the oldest known creature on the planet to possess that peculiar trait.

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