Updated date:

Top 7 Quick and Quirky Facts About Plesiosaurs

Jana loves unusual history. She strives to share the bizarre and funny cases of yore with kindred spirits.


1. Great Moms

Plesiosaurs were marine reptiles. Researchers now believe that they shared a trait with another aquatic reptile. Similar to crocodile females, plesiosaurs were most likely doting mothers. The suspicion had always been there, largely because the creatures were too massive to drag themselves to the shore and deposit eggs like a turtle.

Scientists speculated that plesiosaurs gave birth to live young, instead of eggs. Recently, the proof finally arrived. The fossil of a pregnant plessie turned up, clearly showing that she carried a single, large baby. Just like other marine animals that bear single young, plesiosaurs infants probably received prolonged parental care after birth.

2. They Had Back Problems

In 1970, paleontologists found something rare — disease in a fossil. Usually, ancient bones show scars, breaks and teeth marks. Finding signs of illness in a fossilized skeleton is exceptional. In this case, scientists examined the spine of a plesiosaur. They found lesions from a spinal condition known as Schmorl’s nodes. The animal had it bad, 24 of the 27 vertebrae examined were affected.

In humans, Schmorl’s nodes is a common disease. However, finding it in a plesiosaur was unique on several levels. This was the first time the condition turned up in any aquatic animal, reptile, or non-human for that matter. Their long necks might've played a role in developing spine-related problems. The pure length placed a lot of stress on the bones.

3. A Gem Called Eric

In life, Eric was a pliosaur. They were closely related to plesiosaurs, but had shorter necks. Sometime after he perished, a remarkable thing happened. The creature's fossilization took an odd turn somewhere, because he turned into the semi-precious gemstone known as an opal. There was even an opal fish inside its stomach.

The 7-foot find was unique. However, it was a scary moment for paleontologist when they realized the owners of the opal mine wanted to sell Eric as raw material to jewelry makers. A hugely successful public campaign raised enough funds to purchase Eric, after which he was donated to the Australian Museum.

Eric's Neck Bone

The beautiful colours of an opal, that once was part of a plesiosaur's neck.

The beautiful colours of an opal, that once was part of a plesiosaur's neck.

4. The Loch Ness Bones

Loch Ness in Scotland is said to harbour a monster. Perhaps, a surviving relic from the dinosaur age. Either way, many people have made the link between witness reports of Nessie and a resemblance to plesiosaurs.

One day, a pensioner strolled along the shore of Loch Ness. At one point, he found bones. When it became clear that the pieces belonged to a plesiosaur, believers touted this as evidence that there was a surviving Jurassic population in the water. Sadly, the bones were not new. This particular plesiosaur died 150 million years ago. In addition, Loch Ness only formed 12,000 years ago.

5. They Flew

Since the discovery of plesiosaurs several decades ago, their locomotion was like paleontologists' dandruff (it made them scratch their heads a lot). Nobody could figure out how these creatures moved their big bodies through the water.

With the advent of better computer technology, came the chance to solve the mystery. Scientists fed data into a program to mimic the likeliest swimming style — and it erased any chance of a swimming style. Instead, it revealed the ancient giants flew through the water like penguins. The study found the hind flippers were close to useless and contributed nothing to the animal's speed. Instead, the carnivores flapped their front flippers; literally flying under water.

Powerful Paddles

Simulations showed the front flippers drove the animal forward, not all four legs, despite that they were similar in size and build.

Simulations showed the front flippers drove the animal forward, not all four legs, despite that they were similar in size and build.

6. They Snacked on Birds

A whopping 70 million years ago, a sea bird almost became dinner. This story would have been lost in time had its skeleton not ended up in a museum. When researchers looked at the leg bone, they found bite marks. Signs of infection and healing showed that it survived the attack.

The researchers sleuthed through all their meat-loving fossils. The only teeth that fit were those of a juvenile plesiosaur skull. It would appear that, millions of years ago, a young plesiosaur noticed the diving bird and took a chance. Perhaps because of its youth, the hunter failed.

The find was a game changer. Previously, marine birds weren't believed to bob around on the plesiosaur menu. The bone strongly suggested that the reptiles ate birds when the opportunity presented itself.

7. The Plesiosaur Puzzle

In 2014 an amateur paleontologist named Jonathan Bow found a skeleton. It was the biggest fossil ever discovered in Wales. Unfortunately, when he tried to move it, Bow accidentally broke the 200-million-year old reptile (ironically, into 200 pieces).

Did he run away and pretend it wasn't him? Nope. He spent the next two years gluing the giant back together. The species, Avalonnectes, is also now Wales' most complete plesiosaur fossil. This guy deserves a medal.

Questions & Answers

Question: Were plesiosaurs dinosaurs?

Answer: Plesiosaurs were not dinosaurs. They were an incredibly successful group of marine reptiles that first appeared during the Triassic period about 200 million years ago.

© 2019 Jana Louise Smit


Jana Louise Smit (author) from South Africa on February 23, 2019:

Agreed, Stan. They have a special, almost otherworldly vibe that's very magnetic. A pity we don't have a few running around anymore! :)

Stanley Johnston on February 23, 2019:

Interesting. Ive been intrigued by dinosaurs since I was a kid.