Plesiosaurus Facts: The Intriguing Mystery of It

A plesiosaur is hunting in the sea

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Of everything fascinating and breathtaking, the mystery of the plesiosaurus that traversed the Pacifics of North America, Australia, and Asia is pretty unfathomable. However, scientists have unearthed evidence of the plesiosaurus’s supposed existence and driven the paleontologists head over heels.

This reptile lived more than 200 million years ago and was quite an intimidating marine giant. Its characteristic signature appearance was an elongated neck, a stretched, flat body, sharp teeth, and a long tail. It’s believed that this reptile lived on the land before retreating into the waters, where it became successful in the shallow Jurassic seas.

This article offers the nitty-gritty of the plesiosaurus facts and unearths a mysterious world and time this marine reptile existed.

Quick Plesiosaurus Facts

A plesiosaur and a giant shark-like reptile are fighting in the water

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  • Paleontologists have discovered more than 900 plesiosaurus fossils.

  • Unlike dinosaurs in the Triassic era, the plesiosaurus gave live birth instead of laying eggs.

  • The plesiosaurus was carnivorous creature. (They had large sharp teeth, adapted to gripping and ripping large animals apart. )

  • The plesiosaurus was among the tiniest plesiosaurs, measuring 4.5 meters’ long.

  • Plesiosaurs were characterized by a broad flat body with a very short tail.

The Plesiosaurs: What Are They?

The famliy of plesiosaur

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Plesiosaurs Description & Size The name plesiosaur is derived from the Greek words plesios , meaning close to , and sauros , meaning lizard . The name alludes to the reptilian nature of their fossilized remains.

The plesiosaurs are extinct Mesozoic marine reptiles that lived in the Pacific Ocean in million years ago. Contrary to popular belief, these reptiles were classified as dinosaurs since they didn’t share similar characteristics. They didn’t have an upright posture like most dinosaurs and had four flat paddles to help them cruise the seas. But in artistic depictions, many artists do not draw a distinction between these types of Plesiosaur. Additional, much of the art depicting the Plesiosaurus is heavily influenced by cryptozoid mythology surrounding the Loch Ness Monster and other similar creatures.

plesiosaurs fossil 1

Over the years, many fossils were discovered in the Lias Formation which were attributed to the Plesiosaurus. Nature of fossils The remains found by Mary Anning consisted of almost the entire skeleton. Before her discovery, a few odd bones of the Plesiosaurus were available but they remained unclassified.

However, they were closely related to dinosaurs and had identical reptilian streaks like dinosaurs, including tough skin,sharp teeth, long necks, small heads, and blood as cold as any other animals in the kingdom. Paleontologist Mary Anning discovered the plesiosaurus remains at Lyme Regis in the UK in 1823. The Plesiosaurus was the first plesiosaur to ever be discovered and during the early nineteenth century, only a handful of Mesozoic aquatic reptiles were known However, it’s believed that its fossils might have come to book way back in the eighteenth century. Because in 1719, William Stukely had described a partial skeleton of a Plesiosaurus.

What Did the Plesiosaurus Eat?

A group of plesiosaurs are swimming in the sea

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Plesiosaurs were predators and mainly bottom feeders. According to National Geographic, this aquatic reptile savored pretty-much anything that cruised the sea bottoms, including virtually every benthic animal, including mollusks, squids, and other fish. Its U-shaped jaw was almost like a trap for fish, and while its tail was incredibly short, this seemed less to struggle to find food.

Also, the fact that its usual prey were the slowest animals, including slugs and other benthic invertebrates, it seemingly had no fights to endure. However, they occasionally ventured the upper seas, chasing nimbler swimmers, including a vast array of bony fish.

What Is Unique About Plesiosaurs?

A plesiosaur in the sea

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Plesiosaurs were unique predators among other sea swimmers, thanks to their long necks and wing-like paddles to aid locomotion. Besides, they had incredibly short tails and small heads that appeared insignificant for their swim in the water.

They were efficient swimmers and adept at turns on tight tangents. They also had thicker torsos, sharp teeth, thicker skin, and serpent-like heads. Unlike most marine animals, plesiosaurs were more or less like dinosaurs, only that they lived, fed, and reproduced in the ocean, only coming out occasionally.

Note! Please note the difference between the two suborders: Plesiosauroidea and Pliosauroidea; the former had longer necks than the other, which had short necks.

Did Plesiosaurs Lay Eggs?

The mother plesiosaur and its baby are swimming in the water

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The truth on whether or not plesiosaurs laid eggs isn’t clear due to the long-standing controversy between the two. However, a few theories may suggest that these creatures lived long enough to evolve into child-bearing reptiles.

According to a publication by the Marshal University Research Corporation, the institution’s paleontologist, Dr. F Robin O’Kefee, helped assert the theory after studying an embryonic marine reptile contained within the fossil of a plesiosaur. While this finding has seemingly settled the debate, a little controversy exists.

Where Did Plesiosaurs Live?

A grey plesiosaur model on the ground

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Plesiosaurs lived in the ocean and, more arguably, never ventured into the land in million years ago. They fed and reproduced in the water for the best of their lives. According to sources, this reptile vastly lived on near-shore estuaries and marginally in open oceans.

However, it’s believed that some species lived on freshwater bodies since they were incredibly hardy and adaptable to every aquatic condition. The plesiosaurus was tinier than other reptiles in the plesiosaur genera. Therefore, it’s pretty reasonable to agree that these animals were capable of living in the shallow freshwater environment.

How Big Is This Reptile?

The fossil of the plesiosaurus on the wall

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As a top predator in the shallow seas, this reptile was inarguably one of the scary sea lizard with a size as big as a car. It was almost a meter high and 4.5 meters long and weighed about 500 kilograms when matured.

The liopleurodon – a variety among the plesiosaur genera– was the biggest and measured about 25 meters long! The plesiosaurus seemed quite miniature but ruled the low seas in its right, comparing the two.

Are Plesiosaurs Extinct?

The skull of a plesiosaur with sharp teeth

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All plesiosaurs became extinct almost 66 million years ago during the K-T event. However, their fossil remains have offered a basis for documenting their early lives, including their feeding and reproductive habits.

That’s established ground for sculpting and creating synthetic plesiosaur products, including costumes, puppets, and animatronic forms. Although more is yet to be revealed, existing evidence fossil evidence suggests that these reptiles have no modified descendants currently alive.

Did Plesiosaurs Go On Land?

Two plesiosaurs with the Jurassic Wolrd logo

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According to Dr. O’Keefe, plesiosaurs had no physical ability to climb on land, so it’s fair to reason that they never had their chance on land. However, it’s believed that these animals once lived on land during the Triassic period but switched allegiances with the waters later.

The current controversy is that these reptiles stepped on land, but it’s unclear what their motive was. That’s because most reptiles get on the ground to lay eggs, and plesiosaurs gave live births in the past instead.

Frequently Asked Questions

3D art of a grey plesiosaur in the sea

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What Did the Plesiosaurus Look Like?

The plesiosaurus appeared more like any dinosaur but had paddles for limbs, a long neck (like the snake), small head, and a tiny head. It also had a short tail that seemed insignificant for its propulsion. Remember that all reptiles in this genera had varied physical characteristics compared to the plesiosaurus. If you want to learn more about long-necked dinosaurs like it, you can read the blog A Fun Guide to Long Neck Dinosaurs [With 10 Dino Names].

Is Plesiosaurs a Dinosaur?

All plesiosaurs weren’t dinosaurs, including the plesiosaurus. They had no limbs to help them walk on land, declassifying them as one. However, they shared a few similar streaks, like thick reptilian skin and body forms.


A long neck reptile in the grass

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The Triassic period had its fair share of fascination and wonder, many marine fossils have been excavated from this formation, evident in the long-standing fossil discoveries. These findings have unearthed an ancient mystery, including a world of plesiosaur that lived on earth long before humans. While scientists are still collecting new evidence and findings on these reptiles, the current information remains intriguing.

If you want to know more about dinosaurs like it that can swim or live in water, you can read blog Top 8 Swimming & Water Dinosaurs. Maybe you are also interested in another special dinosaur in the blog What Dinosaur Has 500 Teeth? Get to Know the Cool Nigersaurus.

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