Top 10 Scariest Prehistoric Sea Creatures

by World's Top Insider

Barracuda, sharks, super-squid, and maybe even Cthulhu make the current ocean a terrifying place to be. The largest marine creatures ever discovered were really huge sea lizards, monster sharks, and even “hypercarnivore” whales, all of which lived in the oceans long before humans swam there. Most of these creatures would hardly consider a person to be food.

Ten of the most terrifying marine creatures from ancient times are listed here.

10. Megalodon

megalodon by Johnson-Mortimer on DeviantArt

Perhaps the most recognizable of them is the megalodon; the concept of a shark the size of a school bus is hard to shake from the public consciousness.

Furthermore, science-based entertainment outlets like the Discovery Channel are crazy about animals that seem like they might star in a horror film.


9.   Liopleurodon

Liopleurodon by Johnson-Mortimer on DeviantArt

The Liopleurodon would have made an appearance in the aquarium sequence in Jurassic Park if the film had included more prehistoric species.

Some experts have claimed that these creatures could reach lengths of over 50 feet, but most believe that they were closer to 20 feet long, with a full fifth of that being their pointy-toothed head. If the “smaller” estimate still has a mouth big enough to swallow you whole, then I’d say it’s OK.



8.   Basilosaurus

File:Basilosaurus cetoides skeleton.JPG - Wikimedia Commons

That’s a whale (and not even the scariest one on the list), despite the name and look suggesting otherwise. The 50- to 85-foot-long basilosaurs were the carnivorous progenitors of today’s whales.

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Because of its length and slenderness, it has been likened to a snake more than any other whale. Try to picture yourself sharing the water with an 80-foot-plus alligator-snake whale.

Think about how you would feel if you were terrified of taking a bath.



7.   Jaekelopterus rhenaniae

Sea scorpion, artwork - Stock Image - C015/3215 - Science Photo Library

Nothing about “sea scorpion” is reassuring, so it shouldn’t come as too much of a shock to learn that this creature was one of only two of its kind to ever exist and that it could grow to be more than 8 feet of armoured, clawed evil.

Most of us would probably scream like a small girl if we ever came face to face with a real ant an inch long or a spider a foot wide.

6.   Mauisaurus

Taniwhasaurus vs. Mauisaurus | Canterbury Museum | Craig Dylke | Flickr

You may expect a massive creature from Mauisaurus since it was named after the Maori deity Maui, who used a fish hook to raise the islands of New Zealand out of the ocean.

For a living creature, Mauisaurus had the longest proportional (and actually “actual”) neck, reaching up to 49 feet in length. This excludes sauropod dinosaurs.


5.   Dunkleosteus

Model of Dunkleosteus terrelli (fossil placoderm) (Late De… | Flickr

Dunkleosteus, a carnivorous tank 30 feet in length, existed. Even if sharks eventually killed it out, I doubt that’s much comfort to the many animals it feasted upon.

Its jaws were ridged like a turtle’s instead of having teeth. The biting power of these creatures was estimated to reach 8,000 lbf/in2, making them among the strongest biters in the animal kingdom.


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4.   Kronosaurus

Kronosaurus by arvalis on DeviantArt

Similar to the pliosaur ranked ninth, Liopleurodon, Kronosaurus had a small neck, and its total length is debatable.

It measured a “mere” 30 feet in length and had teeth up to 11 inches in length. This is why it was given the name of the ancient Greek Titan ruler, Cronus. Try to guess its home.

If “Australia” was your answer, you’ve clearly been paying attention (and were right). The head may reach a length of 9 feet.



3.   Helicoprion

Helicoprion, a shark/ratfish (one of the most bizarre prehistoric creatures) | Prehistoric creatures, Weird sharks, Prehistoric animals

These sharks reached lengths of about 15 feet and had a “tooth whorl” in their lower jaws. When apex predators and power tools collide, the earth trembles. This creature looks like a hybrid between a circular saw and a shark.


2.   Livyatan melvillei

Livyatan Melvillei / Prehistoric Mammals on Behance

Do you recall me suggesting that certain whales are “hypercarnivorous”? So, there you have it. The offspring of an orca and a sperm whale would be quite a sight. The Livyatan melvillei whale was known for its cannibalistic appetite.

Its longest tooth measured in at 1.18 feet, making it the largest predatory tooth ever recorded (elephant tusks are longer, but they are just used for show and to help them crush objects; elephants do not use their tusks for eating).

The Megalodon and this whale competed for the same food source, the waters, and the attention of predators.

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1.   Large Stingray

See Freshwater Stingrays at the Smithsonian's National Zoo… | Flickr


What could pull a boat full of people 17 feet, have a venomous spike in its tail 10 inches long, and grow to a massive size? In this scenario, a dinosaur-era super fish can be found in both fresh and salt water from the Mekong River to the northern coast of Australia.

Just like the sharks they evolved from; stingrays have been present for a long time (a few million years after the extinction of the dinosaurs.




Dinosaurs lived over on Earth for more than 150 million years, making them the unchallenged kings of our planet throughout that time. They would have most likely continued to dominate even up to this day if it weren’t for the devastating comet that hit our planet some 65 million years ago and drove them to death. It is still an untruth to believe that dinosaurs were the scariest animals to ever walk the Earth since our world has existed for a considerably longer period of time than the time when dinosaurs ruled.


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