From a coil full of teeth to fins bending over its head, here are 10 of the strangest
prehistoric sharks!!
10. Hybodus
The first teeth of Hybodus were found in England in 1845. They decided to call this animal
the Hybodus which means “Humped Tooth” because of their unique shape. They lived
in the oceans between the Late Permian Period and the Late Cretaceous period- about 259
million to 66 million years ago. Almost 200 million years is an incredibly long time for
a shark species to be around, with most only lasting for a tenth of that. It’s therefore
thought to be one of the most effective shark species to have ever lived, particularly because
it wasn’t the dominant predator at the time- it had to contest with much larger monsters
like the Plesiosaurs and Mosasaurs.
The Hybodus sharks were very similar to today’s great whites, but a bit shorter. They were
6 feet long and weighed up to 200 pounds, which would make them just a bit bigger than
an average human male. They were well adapted to the treacherous oceans because they actually
had two sets of teeth. They preyed on fish, whales, and small marine animals- and their
first set of teeth were used to tear them apart. Their second set of teeth, on the other
hand, jutted out from their jaws- and it’s thought that these were used for defensive
purposes against the much larger predators that they had to face!
9. Scapanorhuynchus
The Scapanorhynchus is a prehistoric shark that resembles today’s Goblin sharks. They
had a long protruding snout that is thought to have contained electrical sensors to help
them hunt prey in the dark, deep waters in which they lived. Here, vision would be completely
useless, but the snout’s ability to detect electrical impulses of other living organisms
would allow the shark to hone in on them without much difficulty. Who needs eyes in the deep
sea anyway?
Fossils have been found that suggest they grew to up to 10 feet long, but also as small
as 20 inches. They are thought to have lived between the Aptian period and the early Paleogene
period, which means from about 120 to about 70 million years ago. Their teeth were relatively
big compared to the size of their bodies, but one particularly interesting physical
characteristic was the formation of their fins. Their tail fin was much larger at the
top than the bottom, which would suggest they weren’t very strong swimmers in open water.
This shape is not very convenient which probably means that they would instead lurk near the
ocean floor waiting for prey to swim nearby.
8. Mongolepis
With fossil records of Mongolepis dating back to about 420 million years ago, it’s one
of the earliest species of shark that existed, along with the Ele-gestol-epis and the Poly-mero-lepis.
Very little is known about how these sharks lived, what they ate, or what they even looked
like so I don't really have that many pictures for you!! In the meantime here is a random
picture to keep you entertained!! All that remains are extremely rare fossilized
teeth, and even they are very different to those of the sharks that we see today.
By far the most unusual thing about the Mongolepis, though, is that they had scales. Modern day
sharks have evolved with skin that is made from tooth like structures, known as placoid
scales- but the scales of the most ancient sharks are far more similar to that of other
fish. This further supports the idea that they were among the very first species of
shark, because they would have only just begun to take a different evolutionary route to
other types of fish that they shared the same ancestors with. Other than that, you have
to kind of put your imagination to work to decide what they might have looked like.
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7. Stethacanthus
The Stethacanthus lived between 390 and 320 million years ago. Fossils were first found
in the 1800’s, but have since been discovered across America, Russia, China and Europe.
This shark’s name translates as “chest spike”, and it’s clear to see why. Not
only did it have small spike-like structures on top of its head, but the males also had
an unusually shaped fin from their upper back, which was also covered in spikes. At first
no-one understood why such an adaptation would develop, I mean, what was that thing for?
It’s now thought that it helped them stay attached to females while mating.
They weren’t a very large species, growing up to 2 or 3 feet long, and weighing up to
20 pounds. The shape of their fins, particularly with the spikey growths on them, meant that
they weren’t very fast or agile in the water, and were most likely bottom feeders who targeted
slow moving prey. Its small teeth wouldn’t have allowed it to attack anything too large,
but would have been more than enough to tear the flesh of small fish, and to help crack
open crustaceans.
6. Falcatus
The Falcatus was a very strange looking prehistoric shark. Whereas the dorsal fin in most fish
rises and curves backwards, that of the male Falcatus’ actually bends forwards over its
head. The fact this only occurs on the males would suggest that it’s only for display
purposes, and didn’t have any offensive or defensive abilities.
The shark, itself, was only about 10 inches long, and had very large eyes in comparison
to its body size, which implies that they lived in fairly deep waters where only a small
amount of light was able to reach. The orientation of their fins would have allowed them to swim
fast through the water, so they would have been able to chase after any small fish or
invertebrates with ease. A number of fossils have been found of Falcatus in the Bear Gulch
Bay, in what is now Montana, and they date back to about 360 million years ago.
5. Xenacanthus
Xenacanthus lived in both salt and freshwater about 200 million years ago. Fossils have
been found in the US, Europe, and India, but their habitat is thought to have been much
broader because of the wide range of environments they could survive in. Growing up to 3.5 feet
long, the most striking thing about this shark is that it hardly looks like a shark at all.
If anything, it looks much more like an eel. It also had a spike that protruded from just
behind its head, and this was probably used as a defensive mechanism to deter potential
predators. Some researchers have even suggested that this spike could have been poisonous
like those of a ray- after all the two species aren’t all that different.
It also had unusual shaped teeth, which are a v shape. This would have allowed them to
exert much greater pressure, and would have been ideal to crush through the protective
shells of their prey- like crustaceans and heavily scaled fish.
4. Edestus
The Edestus lived about 350 million years ago, and was a very strange looking shark.
While most of its body is similar to those of the sharks you see today, the most striking
feature was its head, with arcs of teeth on both the roof and the floor of its mouth,
each protruding away from it. Since its first discovery, paleontologists have wondered how
it would have used this configuration to eat its prey.
Recent research has suggested that rather than crushing meals with its teeth it instead,
used them in a vertical thrusting manner. By moving the front part of its body up and
down, it would have stunned and torn its prey enough that it would be able to swallow it
whole within a few seconds.
3. Cladoselache
The Cladoselache, which means “branch toothed shark”, lived about 365 million years ago.
Fossils have so far only been found in the USA, and it’s often regarded as one of the
first true sharks to enter the fossil record. Despite this, there are a number of differences
between this species and those that we see today.
Growing up to 6 feet long, there are 2 things missing from the Cladoselache that other sharks
have- their claspers. These are the missile-looking projections that sharks have on their undersides,
and are the means for them to transfer sperm between them and their mate. Without these,
it’s unknown how this species was able to reproduce, with some thinking they were more
like ordinary fish in this sense.
The mouth is also more fish-like than today’s sharks, but it would still have had powerful
muscles behind the jaw that allowed it to tackle larger prey. Its eyes were positioned
really far forward on the head, which suggests it relied quite heavily on vision to navigate,
and would have, therefore, swum in shallower waters. The streamlined body shape shows it
was an extremely agile predator, something that is backed up by the type of teeth it
has and the remnants of prey that have been found in fossils. Most food found in their
stomachs had been eaten tail first, having been caught by the shark, and the teeth are
far more effective at grabbing prey, as opposed to slicing through it.
2. Helicoprion
The Helicoprion is, without a doubt, one of the strangest species of shark to have ever
lived. They lived around 270 million years ago, and the first fossil of the 20 foot beast
was found in 1899 by a Russian Geologist.
Since the discovery of the remains, there have been various theories on how the teeth
actually fit inside the Helicoprion’s mouth, because of their unusual shape. Was it more
like a sawfish, curling up and out, or maybe even the complete opposite? Recent research,
and further specimens, have shown that the truth is maybe stranger than people had expected.
The whorl of teeth is now thought to have sat inside the mouth, almost like a tongue,
completely contained within the lower jaw- continually growing up. This is likely to
make up for the fact that it didn’t have any teeth at all on its upper jaw, and would
have helped break down the soft bodied prey, like fish and cephalopods, that it fed on.
When it closed its jaw, the lower part would move back and slice the flesh of its meal
towards the back of its mouth.
1. Otodus
Otodus lived about 40 million years ago, and it was a beast. It’s nowhere as big as the
biggest shark ever, the Megalodon, but it would still have dwarfed any shark that exists
today, with a typical size being one and a half times the size of the biggest Great White
Shark on record. They lived in oceans around the world and grew up to 30 feet long. This
didn’t mean that they were the dominant predator of their time, though, because they
had to contend with gigantic predators like the 60 foot Basilosaurus, which was a species
of predatory whale.
If it managed to stay away from these, then it would have been able to stand up against
most other marine creatures, and would have eaten anything it could get hold of- from
large fish to small mammals.
Evidence of the Otodus from the fossil records end when the mega-toothed sharks begin appearing,
and this is believed to be because many of the new species actually evolved from the
Otodus. It quite possibly could be the ancestor to many of the aggressive species that are
still around today. It might be a good thing for mammal’s sake, that it’s no longer
around too!
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