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Sea Monsters: Liopleurodon

Updated on December 10, 2012

The Biggest Predator Of All Time

Liopleurodon was the largest predator of all time, growing in excess of 70 feet in length. Its head alone took up more than a third of its body length.
Liopleurodon was the largest predator of all time, growing in excess of 70 feet in length. Its head alone took up more than a third of its body length. | Source

Earth In The Jurassic

This map shows the positions of the Earth's continents during the Jurassic Period.
This map shows the positions of the Earth's continents during the Jurassic Period. | Source

The Jurassic At A Glance

Time: 155 million years ago.

Location: The sea around a group of islands in what will become southern England. The predators described in this hub are common throughout a whole swathe of northern Europe.

The shape of the continents: During the Triassic the world was made up of one gargantuan supercontinent called Pangaea, but by the Jurassic this is starting to break up into two massive continents called Laurasia and Gondwana.

Fauna: This is the time when animals in North America and Europe reach their most extreme sizes, both on land and in the sea. As well as behemoths such as Leedsichthys and Liopleurodon, the Jurassic saw the evolution of the most colossal dinosaurs of all, the sauropods.

Hazards: In the oceans there'sLiopleurodon, Metriorhynchus and Hybodus sharks. The oceans are affected by super hurricanes that feed off the energy stored in the water. From time to time, Jurassic storms are of such staggering brutality that they stir the ocean floor and kick up enormous waves that can swamp entire islands, killing everything living on them. On shore, while the smaller islands are predator free, the larger ones support predatory dinosaurs such as the 16 foot long Eustreptospondylus, and its much larger and more famous relative Allosaurus, which is 40 feet long.

A Reptilian Dolphin

An ophthalmosaurus swimming past an ammonite in the warm Jurassic seas.
An ophthalmosaurus swimming past an ammonite in the warm Jurassic seas. | Source

Ophthalmosaurus

A fast moving ichthyosaur, ophthalmosaurus used its speed to catch fish and squid and to outrun its many enemies.

Time: 165-150 million years ago.

Size: Up to 16 feet in length.

Diet: Fish, ammonites and belemnites.

Evidence: Fossil finds have been made inArgentina, England and Germany.

Fact: Ophthalmosaurus had the largest eyes of any marine reptile.

An Oceanic Crocodilian

As an ocean going crocodilian, any time travelling human would have to afford it the same respect they show to its modern freshwater relatives.
As an ocean going crocodilian, any time travelling human would have to afford it the same respect they show to its modern freshwater relatives. | Source

Metriorhynchus

Metriorhynchus was an ancient relative of the crocodile that spent almost its entire life at sea. As well as hunting fish, it also liked to hide just under the water and grab passing pterosaurs.

Time: 160-150 million years ago.

Size: 10 feet in length.

Diet: Ammonites, belemnites and large fish.

Evidence: Fossil finds have been made in England, France, Chile and Argentina.

Fact: This snappy hunters could grab pterosaurs in mid flight.

The Biggest Fish That Ever Lived

Leedsichthys was the biggest fish that's ever lived, comparable to a blue whale in size.
Leedsichthys was the biggest fish that's ever lived, comparable to a blue whale in size. | Source

Leedsichthys

Despite its size, Leedsichthys was a gentle filter feeding giant. Unfortunately its size could not protect it from attack by other predators.

Time: 165-155 million years ago.

Size: Nearly 90 feet in length.

Diet: Small shrimps, jellyfish and small fish.

Evidence: Fossil finds have been made in England, France and Chile.

Fact: Leedsichthys had over 40,000 teeth which were used to sieve small animals from the water.

Deadly Paradise

Close your eyes and think of England, more specifically, try to paint in your mind’s eye a picture of the English countryside. A rolling expanse of hills, rivers, forests, lakes covered with grasses and deciduous trees such as oak, hazel and beech. The sea is icy cold, there are four clearly defined seasons and overall the weather is, well, speaking as an Englishmen, it could be better. Picture yourself there: the chill wind on your skin, the smell of wet bark and grass, the sound of birdsong. Now get ready for a shock as we travel back 155 million years to the England of the Jurassic, the difference will simply blow you away.

The Europe of 155 million years ago is a completely unfamiliar world, flowers and grass, along with a whole host of other plants we take for granted are entirely absent. Instead there is a spiky cornucopia of prehistoric flora such as conifers, ferns, column pines, cycads, bennetites and horsetails. The air doesn’t dance with the twitter of birds, but is instead ripped up by the screech of pterosaurs with the occasional groan from a distant dinosaur. The climate is tropical, with seasons to match; a wet and dry season instead of summer, autumn, winter and spring. In fact the climate on Earth is about as hot as it has ever got and the winter here is a pleasant 70 degrees, as opposed to the 50 degrees that the likes of me and other present day English are used to. But the most important difference of all is the sea level, which in the Jurassic is some 330 feet higher than it is today, so that vast tracts of Europe aren’t land at all but seabed. With only the highest points above water, Jurassic Europe is not so much a landmass as a huge tableau of glittering islands set in a warm, shallow sea.

In fact, from above the water the England of 155 million years ago looks much like paradise, but beneath the waves lives such a fearsome collection of predators that you would have to be virtually insane to get in the water here. This is one of the deadliest oceans of all time.

To understand what makes this environment tick we need to start at the smaller end of the food chain. This shallow sea is a fertile one, rich in nutrients and capable of supporting life in abundance. Nutrients are washed in off the land and, because the water is shallow, passing storms also stir up organic matter from dead animals on the seabed. (And this place sees some pretty monumental storms.) It’s the perfect environment for plankton to thrive and at times the water gets so thick with these teeming micro-organisms that the sharks can barely see past the end of their noses. The plankton supports larger animals such as the distinctive ammonites and the ubiquitous belemnites- squid-like animals with a hard shell on the inside of their bodies.

All of this and the plentiful fish are food for the ’devil-horned’ shark, hybodus, and a whole array of sizeable marine reptiles; long necked plesiosaurs such as cryptoclidus, the big eyed ichthyosaur ophthalmosaurus and the extraordinary metriorhynchus, a 13 foot long close relative of crocodiles but totally adapted to an oceanic lifestyle. Metriorhynchus is descended from a forerunner of the crocodilians, on first glance it resembles the freshwater crocodiles of the present era, but the course of evolution has substantially modified its body for a marine existence. The feet have become flippers and the heavy armoured scutes of freshwater crocodilians have been lost in favour of sleek skin, for speed in the water. And there’s nothing crocodilian about the tail either, it has developed a fluke much like that of a shark for great bursts of speed. But metriorhynchus still retains some close similarities to its freshwater relatives; a lethal set of teeth and the crocodilian trait of eating everything and anything that it can, including fish, belemnites, ammonites and even the occasional pterosaur as it swoops down to catch fish. They are more particular about where they live, they like warm, salty water and tend to favour the shallower areas no more than a couple of days’ swim from land. So as far as the metriorhynchus are concerned, the warm shallow waters around the islands of what will one day become England are just about perfect.

If that’s not enough then there are the big fish, and when I say big, I mean really big. In fact the biggest fish ever, leedsichthys, a beast that can grow up to 90 feet long is a common sight here. In comparison, the biggest fish alive today, the whale shark has been recorded at nearly 70 feet in length, but only in rare cases. Like whale sharks, leedsichthys are gentle giants, no danger to anything much larger than plankton, which they sieve out through an arrangement of 40,000 superfine teeth arranged in rows in front of their gills. At certain times of year, when the water goes milky with an explosion of plankton, they cruise open mouthed through these islands in great shoals, like underwater zeppelins. Anyone who has swum with a whale shark will testify that it is an awesome experience. But then they haven’t been in the Jurassic among a whole shoal of leedsichthys.

You’d have thought that a fish of this size would have little to fear from other animals, but there are at least two predators native to this area that will attack a full grown leedsichthys. The first one is, somewhat surprisingly, metriorhynchus. In keeping with its opportunistic style of hunting, it has been known to take bites out of live leedsichthys. As if being eaten alive wasn’t bad enough, the second threat facing these huge creatures is a more terrifying beast altogether; again a reptile, but one that is almost as large as leedsichthys. Arguably the largest predator, on land or in the sea of all time: liopleurodon.

Opthalmosaurus Giving Birth

The Ultimate Marine Predator

A fossilised skeleton of liopleurodon, showcasing that massive jaw and those formidable teeth, which incidentally are the biggest known.
A fossilised skeleton of liopleurodon, showcasing that massive jaw and those formidable teeth, which incidentally are the biggest known. | Source

Liopleurodon

The largest predator of all time, Liopleurodon was capable of attacking and eating most animals in the ocean. As an air breathing marine reptile it stayed close to the surface and would probably have fed on other marine reptiles such as the ichthyosaurs.

Time: 160-155 million years ago.

Size: Up to 80 feet long.

Diet: Other marine reptiles, large fish, belemnites; almost anything it could catch and swallow.

Fossil finds: Fossil finds have been made in England, Germany and possibly Mexico.

Fact: Liopleurodon's teeth were twice as long as those of Tyrannosaurus.

Clash Of The Titans

Liopleurodon, the biggest predator of all time harrassing the biggest fish of all time, Leedsichthys.
Liopleurodon, the biggest predator of all time harrassing the biggest fish of all time, Leedsichthys. | Source

Liopleurodon On Film

The Biggest Predator Ever

That something far, far bigger than cryptoclidus, ophthalmosaurus or metriorhynchus hunts in these waters is obvious from the occasional partial skeleton on the seabed; here and there a complete tail, without a single bone from the rest of the body; elsewhere a head and forelimbs, with no trace of the tail. These are the remains of animals as much as 20 feet long that have been quite literally bitten in half.

Only a few times in its history has Earth witnessed a predator anything like the size of the culprit. Large male liopleurodon can reach 70 feet long, and there are thought to be a few exceptional individuals out there that touch 80 feet. No one knows for sure, but teeth marks have been found in the bones of prey that can only have been made by a pliosaurs of that size (‘pliosaur’ is the name given to short necked plesiosaurs like liopleurodon). This is double the length of the largest land predator of all time, the dinosaur giganotosaurus, which measures a meagre 40 feet from head to tail. In the sea, though, animals can grow to be a whole lot bigger and there are one or two marine predators in the same size range as liopleurodon. Sperm whales over 70 feet have been found (and who knows what we haven’t found?), and in the Triassic some ichthyosaurs grew up to 80 feet. But while sperm whales, ichthyosaurs prey on things like squid, liopleurodon is equipped to kill much larger animals, making it a meaner monster all round.

The head alone is over 10 feet along and home to a fearsome collection of dagger like teeth, the longest of which are at the tip of the snout. Eyes on top of its head reveal that liopleurodon attacks from below, while its chest shows an animal engineered for explosive ambush. A reinforced ribcage harbours colossal muscle structures designed to pull the flippers down in immensely powerful strokes as it launches itself unseen from the depths.

As with any marine hunter, catching prey is not the whole problem, a predator also has to be able to remove chunks of flesh, something that is far harder to do in the water than on land. (Think apple bobbing, but replace the apple with a 20 foot long reptile in its death throes.) Sharks have solved this problem by having such incredibly sharp teeth that the bite is normally sufficient to remove each mouthful, while crocodiles spin in the water to tear off bits of meat. Liopleurodon meanwhile has the thickest of necks, allowing it to thrash its head from side to side and rip its prey apart.

Reptiles, as a rule cannot smell underwater, whenever crocodiles or turtles dive, they close off their nostrils completely to prevent water getting in. But liopleurodon along with all the plesiosaurs, has an arrangement that is utterly different and is the key to its success as a hunter. Its unique sensory system allows a liopleurodon to detect minute amounts of chemicals in the water, including traces of blood, excrement, an animal giving birth; but most crucially of all, it can tell where these smells are coming from. Liopleurodon smells in the same way that human beings hear; our brain figures out where a sound is coming from through the difference in the sound reaching the right and left ears. For liopleurodon, it’s the smallest difference in smell reaching its left nostril and its right that signals a scent’s origin and allows it to sniff out its prey before it runs any risk of being seen.

More On Liopleurodon And Other Sea Monsters Of The Jurassic

Where Danger Lurks, So Do Sharks

A restoration of Hybodus, a rather devilish looking shark.
A restoration of Hybodus, a rather devilish looking shark. | Source

Hybodus

Hybodus was a true shark and would have hunted and swum in a similar way to most modern small sharks. The spine on its dorsal fin would have deterred predators from trying to attack it.

Time: 230-90 million years ago.

Size: 7 feet in length.

Diet: Fish, shellfish, belemnites and other sharks.

Evidence: Fossil finds have been made in Asia, Europe, Africa and North America.

Fact: The spine on Hybodus' back would have got stuck in the mouth of any potential predator, making it impossible to swallow.

A Modern Spiky Shark

Some modern sharks, like the Mexican horn-shark retain the same spiky defences as the Jurassic hybodus, although they are nothing like as large.
Some modern sharks, like the Mexican horn-shark retain the same spiky defences as the Jurassic hybodus, although they are nothing like as large. | Source

Cryptoclidus

Cryptoclidus was a medium sized plesiosaur, with long, fine teeth designed to catch slippery prey such as fish and squid.
Cryptoclidus was a medium sized plesiosaur, with long, fine teeth designed to catch slippery prey such as fish and squid. | Source

Survival

Okay, we've talked about liopleurodon’s prowess as a hunter, but life is all about balance. Just as predators evolve into more sophisticated killers, so prey evolve into more difficult targets and the creatures that share these waters with liopleurodon have all manner of strategies to keep themselves out of the jaws of death.

For leedsichthys, their size is their protection. A healthy adult is by and large too much trouble for a liopleurodon to take on. But sick or injured individuals, particularly those that have become separated from the shoal, are vulnerable to attack.

For the smaller marine animals, survival comes down to three things; senses, speed and spikes. Ophthalmosaurus’ most distinctive feature, and one critical for its survival, is its huge eyes, which are capable of seeing in the gloomiest of conditions. There is an obvious two fold advantage for the animal, firstly it can pick out its prey and it can out-see its predators. Ophthalmosaurus’ superlative eyesight allows it to hunt squid and belemnites at night, when it’s safest from a liopleurodon attack. Though smell is important to liopleurodon in finding its victims, it relies heavily on sight to make the kill; like other marine ambush predators such as the great white shark, it spots its victims by looking out for silhouettes at the surface. At night there are no silhouettes.

Other senses play a big part in cryptoclidus’ self preservation. Being a plesiosaur, cryptoclidus boasts the strange ability to smell underwater as liopleurodon does, together with a sense of hearing completely adapted to the marine environment; unlike those of its land ancestors, cryptoclidus’ ear-bones are fused together. This arrangement might make cryptoclidus virtually deaf above the water but, due to the way sound waves travel through water, it’s remarkably attuned to sounds beneath it. Such a specialised sense is as useful in finding something to eat as it is in avoiding being eaten.

When it comes to speed, it is ophthalmosaurus that has the upper hand over virtually every other animal around. Although unrelated, it shares a similar body shape with the speed merchants of the present seas, namely dolphins and tuna. The rounded body, smooth skin and deep, powerful tail allow ophthalmosaurus to reach speeds in excess of 25 miles per hour and outpace any liopleurodon, provided it sees it in time.

Hybodus, of course, has all of these protective mechanisms and more. Like most sharks, it’s fast and has superbly developed senses, especially smell, hearing and sight, together with the ability to detect the electromagnetic signals given off by the muscles of other animals. These all serve to protect it as well as making it an effective predator. But the spikes alongside the dorsal fin are plainly not for hunting. These very same spikes are seen on much smaller present day relatives such as the Port Jackson shark and the Mexican horn shark, where one of their functions is to stick in the throat of any animal that tries to eat them. If a liopleurodon does manage to catch a hybodus, it’ll probably regurgitate it.

Sharks Vs. Reptiles

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    • JKenny profile image
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      James Kenny 4 years ago from Birmingham, England

      Thank you very much Eddy.

    • Eiddwen profile image

      Eiddwen 4 years ago from Wales

      So interesting and thank you for sharing.

      eddy.

    • JKenny profile image
      Author

      James Kenny 4 years ago from Birmingham, England

      Hi Richard, I'm not totally sure, but cryptoclidus certainly looks like the creature said to be Nessie. Whether such a creature has managed to survive in the icy cold water of Scotland is up for debate!

    • rcrumple profile image

      Rich 4 years ago from Kentucky

      Extremely informative and well presented, as always! I studied dinosaurs and such when I was back in school and always found the fascinating. Just out of curiosity, isn't the Cryptoclidus what is still considered to be "Nessie", or the Loch Ness Monster? Just a thought. Great Job!

    • JKenny profile image
      Author

      James Kenny 4 years ago from Birmingham, England

      Thank you Sharkeye, glad to have been of service. Appreciate you taking the time to drop by.

    • Sharkye11 profile image

      Jayme Kinsey 4 years ago from Oklahoma

      You brought back great memories with this. My younger sisters were dinosaur fanatics and they had a collection of books detailing these monsters. Being the older sister, my job was to read these books to them repeatedly, and stumble over the names frequently. It was great though. I learned to like dinosaurs through those experiences.

      Fascinating hub. Love all the facts, and the intriguing presentation.

    • JKenny profile image
      Author

      James Kenny 4 years ago from Birmingham, England

      Thank you Paradise, yes we can't help but be fascinated by these monsters, but if we ever saw them, we'd run a mile or two haha! Appreciate you dropping by.

    • Paradise7 profile image

      Paradise7 4 years ago from Upstate New York

      Well-written on a fascinating subject! Thank you for sharing this with us. I'd really like to see those monsters. Not up close, though. They'd have us for lunch!

    • JKenny profile image
      Author

      James Kenny 4 years ago from Birmingham, England

      Thanks Nettlemere, while I'd have to loved to have walked down the English beaches 155 million years ago, I'd never go swimming. Then again with giant predatory dinosaurs on the land...I think I'm better off in the present. Appreciate you dropping by.

    • Nettlemere profile image

      Nettlemere 4 years ago from Burnley, Lancashire, UK

      Great descriptions as always - you really give a sense of what it might have been like in UK seas millions of years ago and why it would have been safer to stay out of the water!