Did you know that marine life millions of years ago was much bigger, and more dangerous,
than what we see today?
Here are 10 of the scariest ancient sea monsters that ever existed!!
10.
Liopleurodon
Just imagine what it’s like to swim alongside a creature that’s many times your size!!
Pretty intimidating but still nothing like these guys.
The Liopleurodon was one of the largest sea monsters that ever lived.
At about 80 feet long, it was the alpha predator in the shallow waters during the late Jurassic
period, where it hunted crocodiles and giant fish.
It was very well suited to this task with its long jaws and needle sharp teeth, and
it’s nose was incredible sensitive- allowing it to detect prey across large distances.
They did, however, need to breathe air, so their range was somewhat limited and they
weren’t able to go too far deep into the water.
They had flippers to propel them through the water which meant they weren’t as fast and
agile as other creatures at the time, but they more than made up for this with their
ferocious bite!!
9.
Kerygmachela Kierkegaardi
The K Kierkegaardi is a strange creature that lived about 540 million years ago, and recent
discoveries of their fossils have led to a completely new understanding of how animals’
brains have developed!!
Growing up to 10 inches long, (I know, that’s not very much compared to the 80 foot Liopleurodon
I just mentioned, but they still have their merit I promise!)
They were oval shaped, with skinny tails, 11 swimming flaps along each side, and two
unusual appendages that protruded from their heads that they used to grab their prey.
They are distant relatives to arthropods of today, such as spiders, lobsters and butterflies.
Unlike these, though, which have 3 segments to their brains, K Kierkegaardi only had one
segment to its brain, which is a much more primitive structure.
It had long been thought that arthropod ancestors would also have 3 parts to their brains, but
these fossilised discoveries have shown this is not the case.
So now scientists are wondering, when their evolution to a more complex structure actually
happened.
And now for number 8, but first do you know what is thought to be the largest fish that
EVER lived?
Let us know in the comments below!
The answer is coming up!
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8.
Dakosaurus
Dakosaurus lived during the Jurassic and Cretaceous eras about 145 million years ago.
The species is often referred to as ‘Godzilla’ because of the deep shape of its skull, but
it was more like a large crocodile that lived in the saltwater of the oceans.
Growing up to 16 feet long, it had paddle shaped flippers to help propel itself through
the water, as well as a fluke at the end of its tail to provide extra power.
Its large skull and jaw, along with serrated teeth suggest that it had a different diet
to other crocodile species.
Rather than eating primarily fish, Dakosaurus fed on larger prey and, possibly, even other
marine reptiles.
They lived in all the world’s oceans, with fossils having been found in what is now Europe,
North America, South America, and Russia.
Little is known about quite how they lived, and whether they gave live birth in the depths
or lay their eggs in the shallows.
But one thing’s for sure, though- the Dakosaurus was a type of crocodile unlike anything we
see today!
7.
Ichthyosaur
Ichthyosaurs lived during the Triassic period until around 90 million years ago, when they
mysteriously became extinct- about 25 million years before the event that wiped out the
dinosaurs.
Meaning ‘fish lizards’, Ichthyosaurs are actually thought to have evolved from a land
reptile that moved back into the water, but it’s not yet clear what its precise ancestry
is.
It’s a little confusing.
As they were in the oceans for more than 160 million years, there were a number of different
species of Ichthyosaur.
They were at the top of the food chain in the regions for most of this time, but were
eventually replaced by another reptilian creature called the Plesiosaurs.
Because of their streamlined bodies, Ichthyosaurs are thought to have had a top speed of 22
miles per hour through the water.
Resembling fish, some species of could grow to up to 50 feet long!!
They had pointed heads, and teeth designed to catch prey ranging from the smallest fish
to larger, more difficult prey.
6.
The Tully Monster
If you were asked to design the strangest animal you could, then I bet you wouldn’t
come up with something as weird as this odd looking creature, called the Tully Monster.
Fossil findings suggest that it lived in the shallow waters of the Eastern United States
about 300 million years ago, with remains having been found in the Mazon Creek fossil
beds in Illinois.
Lots of them have been unearthed, so they were clearly abundant, but they were a very
unusual combination of body parts, which has made it difficult to classify what the creature
is.
With eyes on long stalks, a pincer at the end of a long arm-like structure, and a body
more resembling a mollusc- various teams have come to differing conclusions about what it
was.
Some think it was a mollusc, others think the signs of gill pouches meant they were
fish, and some even think they were vertebrates because of their complex eyes.
Whatever the true classification is, Tully monsters, named after the fossil collector
who first found them, is one of the strangest looking monsters that’s ever lived in the
oceans, and sure to be the subject of debate for many years to come.
5.
Kronosaurus
The Kronosaurus was a short necked pliosaur that lived during the Cretaceous era, just
over 100 million years ago.
They grew to around 32 feet long, 9 feet of which was its huge head- big enough that it
could fit an entire human inside it!
Remains have been found in Australia and Colombia, where it would have been the alpha predator
of its time.
It had conical teeth which were almost a foot long each!!
Interestingly, unlike other pliosaurs, the teeth were not serrated.
This means their prey was likely made up of medium sized or small fish, and if they were
to tackle something larger they would have needed to rely on the twisting and turning
their huge bodies to tear flesh apart, just like how crocodiles do today.
The Kronosaurus was the second biggest pliosaur to have ever lived, much bigger than the Liopleurodon
which is often cited as the largest of the species.
They were more than 3 times the size of a typical human, and would easily be the most
dominant predator in the oceans if it was still around today.
4.
Anomalocaridids
If you’re squeamish about creepy crawlies, then this next ancient sea monster is probably
going to be your least favourite of all.
Anomalocaridids were shrimp-like creatures that, for millions of years, were the largest
predators in the oceans.
They had soft jointed bodies, and spiny limbs to allow them to catch small prey like worms.
First appearing about 542 million years ago, Anomalocaridids developed at the beginning
of the era known as the Cambrian Explosion, which is when most of the animal groups we
know today first evolved.
Good times, the Cambrian Explosion!!
They grew to up to 3 feet in length, and spent their lives scouring the muddy seafloor at
depths of up to 330 feet.
At this time, the seabed would have been covered in various species of sea stars, sponges,
and molluscs, and would be an ideal feeding ground.
With hundreds of blade like structures across their backs, Anomalocaridids would have easily
swum about picking off their prey, without fear of getting eaten by anything else.
3.
Tylosaurus
The Tylosaurus- a name which means “knob lizard”, was one of the largest mosasaurs
to ever live.
They swam in the oceans during the Cretaceous era, about 70 million years ago, and grew
to up to 50 feet long.
They were different to earlier species of mosasaur that propelled themselves through
the water with flippers and, instead, had giant tails that would do all of the work.
Their tails had more than 80 vertebrae, that allowed them to withstand the pressures involved
in moving through the water, and created a visible v shape pushing through the skin.
Tylosaurus’ would have swum in the waters known as the Western Interior Seaway that
covered the US and Canada, and were the ocean equivalent of the T-Rex at the time.
Their large teeth and powerful jaws made light work of anything they decided to chase after,
and some remains have even been found after having eaten land dinosaurs- suggesting that
they would lurk near the shallows and take advantage of any creature that ventured too
far from shore.
Despite their ability to attack with their teeth, most evidence points towards Tylosaurus’
using their snouts as a battering ram, and preferring to hit into prey at high speeds,
and knock them unconscious before feeding.
This method also means they most likely stalked their prey from below, would take time to
line themselves up, and then strike before the victim knew what was happening and had
time to swim away.
2.
Luskhan Itilensis
The Luskhan Itilensis is a new species of Pliosaur that was only recently identified
in 2017 from fossils found 15 years earlier in the Volga river in Russia.
Rather than being dinosaurs, they were actually distant relatives of turtles- with 4 large
flippers, big heads, powerful jaws, and very sharp teeth.
They lived in the ocean above what is now Europe around 130 million years ago, and their
skulls alone were up to 5 feet long.
The shape of the Luskhan Itilensis head was what made it unique amongst other similar
species- particularly in the way it resembled that of some types of river dolphin, which
would have allowed it to effectively hunt fish.
Pretty cool, right??
1.
Leedsichthys
Growing up to 55 feet long, the Leedsichthys is thought to be the largest fish that has
ever lived.
(So this answer was actually pretty tricky!!)
It’s difficult to know much about it, though, because only fragments of this giant creature
have ever been found.
At one point is was believed to be twice the size, but even the recent reduction in estimates
based on new finds makes it bigger than today’s whale sharks, and by far the biggest bony
fish that’s ever been discovered.
They lived in the oceans around 165 million years ago and, like whale sharks, would have
survived on a diet of plankton.
It’s been a mystery how the Leedsichthys came to grow so large, but the abundance of
food in the oceans at the time could be the cause.
Its size would have been invaluable at the time, because sharing the waters with other
aquatic monsters, like pliosaurs, meant that if you were bigger than the predators, you’d
stand a reasonable chance of evading them because they would, instead, go for easier
prey.
It’s one of those cases where bigger was most definitely better!
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