From whale sized beasts to dolphin-like lizards,
these are 10 of the biggest sea reptiles to have ever lived…. 10. Ophthalmosaurus (16 feet) Ophthalmosauruses lived during the late Jurassic
era about 165 to 150 million years ago and were present in oceans worldwide. Its name, which means ‘eye lizard’ comes
from the fact that it had very large eyes, which were up to 9 inches in diameter (22.8
cm)! They looked particularly big compared to the
size of the rest of its body! They grew to around 16 feet long and weighed
up to 2 tons. This is the equivalent size to a Beluga whale,
but twice the weight! They had a large bony ring in their head that
protected their eyes under pressure, and it’s thought that this signifies that they hunted
in the deeper parts of the ocean. Their increased ability to detect light would
have allowed them to more easily see prey in the murky depths, where they would have
hunted fish, squids, and mollusks. This would also have been an effective way
to evade predators because most other creatures of the time, that were big enough to take
on an Ophthalmosaurus, wouldn’t have wanted to follow them into such deep waters. Some remains have even been discovered with
evidence of decompression sickness, which would only likely happen because of evasive
tactics. It’s not entirely clear why this species
of Ichthyosaur went extinct, but it’s believed it was as a result of increased competition
for food by other ocean animals, such as Pliosaurs and Plesiosaurs. 9. Platypterygius (23 feet) Some of you helped me out the other day when
I asked for advice with the pronunciation so thank you! I’m finally going for it!! The Platypterygius was a dolphin-like Ichthyosaur
that was around during the early Cretaceous period, about 100 million years ago. Growing up to 23 feet, they would have been
the dominant predators of the Eromanga sea in inland Australia where they lived. They hunted fish, squid, and any other marine
life they could catch and had a number of adaptations to allow them to do so. They had long snouts, with as many as 200
conical shaped teeth. Their front and back paddle-shaped flippers
were used to swim through the water, and they had dorsal and tail fins… just like modern-day
sharks. Their front flippers had more digits than
seen in other species of Ichthyosaur, and it’s this reason that they get their name…
which means ‘flat wing’. Like other Ichthyosaurs, they were air-breathing,
and the remains of various subspecies have been found across Australia. We also know more about their reproduction
than a lot of other species, because of some specimens that have been discovered. They gave birth to live young, with the infants
being about 6 feet long and ready to start hunting virtually straight away. 8. Thalattoarchon (28 feet) The Thalattoarchon was one of the first Ichthyosaurs
and lived around 245 million years ago. Unlike others, their teeth were unusual. Rather than the conical shape, they were about
4 inches tall and blade-like with two cutting surfaces. Armed with such deadly weaponry, the Thalattoarchon
is seen as the original oceanic macropredator- one that targets animals of a similar size
to itself, as well as those that are smaller. They are the oldest known reptiles to have
been apex predators in the seas, and were around just 5 million years after the Permian-Triassic
extinction event… the deadliest such event to have ever happened, which was responsible
for wiping out at least 96 percent of marine life. There’s only one known skeleton of a Thalattoarchon
to have been found, and its surroundings give good evidence of why they were so well armed. The remains were dug up alongside other large
ichthyosaurs, and it’s been suggested that this species took advantage of their peers,
and would mainly prey on large marine reptiles. 7. Plotosaurus (30 feet) The Plotosaurus, whose name literally means
‘swimmer lizard’, lived around 70 million years ago in what is now California. They typically grew to around 30 feet long
and were similar to other mosasaurs in that they had large powerful tails for propulsion,
and narrow flippers, but were more streamlined than other species. Plotosaurus is thought to have been particularly
fast, and also had much larger eyes than others, which would have given them a huge advantage
in spotting prey, and predators. They were scaled, and thought to be one of
the last in the line of mosasaurs… seemingly much better adapted to swimming than their
predecessors. They hunted fish, sharks, and smaller aquatic
reptiles, but the lack of fossils that have been found means that no-one’s entirely sure
what their teeth were like, or quite how deadly they were. Only a few specimens have been found, with
some suggesting this species could have grown as big as 43 feet long in the right circumstances. 6. Temnodontosaurus (39 feet) The Temnodontosaurus was a species of ichthyosaur
that lived during the early Jurassic, between about 200 and 175 million years ago. They hunted for food in the deeper parts of
the ocean, and remains have been found across Europe. Their name means ‘cutting tooth lizard’,
and it’s clear to see why. They were one of the largest species of Ichthyosaur,
but it was their robust teeth and deep jaw that enabled them to become an apex predator
and eat fish, other ichthyosaurs, and cephalopods. They also had huge eyes… ones that were
8 inches in diameter, and are thought to be the largest of any animal to have ever lived. Even so, due to their placement, the Temnodontosaurus
would have had a blind spot directly above its head, which is where you’d want to hide
if one of these beasts was chasing you. They were incredibly adept at maneuvering
through the water, and their tails were able to bend to an angle of less than 35 degrees,
which allowed them to quickly change direction and continue the chase. 5. Tylosaurus (45 feet) The 45-foot long Tylosaurus proriger swam
the planet’s oceans around 85 million years ago during the Cretaceous… while T-Rex’s
walked the land. It was a species of mosasaur and is believed
to have been one of the deadliest oceanic hunters of the time- feeding on fish, birds,
sharks, and other aquatic reptiles. They had two rows of cone-shaped teeth on
each side of their mouths, and a sensitive snout to smell out its prey. Two further rows of teeth on the roof of the
mouth ensured that once the fearsome jaws closed on a target, there was no escape. They had long muscular tails to propel them
through the water, and paddle like limbs to help steer. Most Tylosaurus remains have been found in
Kansas, which used to be the site of the Western Interior Seaway, and shows evidence that the
species died out at the same time as the dinosaurs. 4. Prognathodon (46 feet) Prognathodons were huge mosasaurs that could
grow to up to 46 feet in length. They lived around 80 million years ago, and
specimens have been found around the world, particularly in Europe and North America. Unlike other similar species, Prognathodon
had a different way of hunting, adapted better for preying on tough shelled animals like
shellfish, ammonites, and turtles. For a long time, this diet was theorized based
on its incredibly powerful jaw structure and its strong, but serrated teeth that would
have enabled it to break shells and tear up the flesh inside. Two specimens were found in Canada that had
turtles and ammonites actually fossilized where the stomach would have been. Researchers also discovered traces of a long
fish, which suggests Prognathodon were opportunistic with what they ate, as well as tracking down
certain prey. Quite why the Prognathodon went in this dietary
direction, while other, smaller, mosasaurs became apex predators of reptiles and fish
is unclear… it’s thought it could have been a result of increased competition for food
during the period they were alive, and since shelled animals were not the most popular
prey, it gave them a huge source to feed on that enabled them to sustain their large size. 3. Shonisaurus (49 feet) The Shonisaurus lived towards the end of the
Triassic period, around 215 million years ago, and evidence has been found of them swimming
in oceans around the world. Fun fact: 37 fossil specimens alone have been
found in the Luning Formation of Nevada and is the official fossil of the state. They grew to about 49 feet in length, which
is the same as two killer whales placed end to end, and they weighed about the same as
a sperm whale- 30 tons. The Shonisaurus looked like an oversized dolphin,
but the most surprising thing about this Ichthyosaur is that it didn’t have any teeth. The fossil record shows that when they were
young, they did have teeth, but they would fall out as they got older because they simply
didn’t need them. Furthermore, they didn’t have a dorsal or
sail fin either, which meant they wouldn’t have been anywhere near as maneuverable as
other similar animals. Still, their massive size meant that they
probably wouldn’t have had to worry about too many predators, and would have been able
to get on with eating the huge amounts of soft fish and squid that they needed to survive. 2. Mosasaurus (56 feet) The Mosasaurus is probably the most famous
of the Mosasaurs…. If you think the name sounds familiar, it’s
the one that was kept in the lake in the Jurassic World movie. They were one of the last, and one of the
largest species of Mosasaurs, and lived between 70 and 66 million years ago. Remains have been found in Europe and North
America, but it’s thought that they were present the whole world over. Researchers believe that the Mosasaurus lived
close to the surface, where it preyed upon fish, turtles, ammonites, birds, other mosasaurs,
and plesiosaurs. They had large conical teeth that pointed
backwards towards the throat, and their powerful tails provided all the propulsion they needed. These creatures would have been fearsome predators
to everything else in the ocean, but that doesn’t mean they weren’t preyed on themselves. Remains found in Canada have shown a half-eaten
Mosasaurus… seemingly having been attacked by a group of prehistoric sharks. 1. Shastasaurus (60 feet) The Shastasaurus was an Ichthyosaur that lived
in the Pacific Ocean during the Late Triassic period, around 215 million years ago, and
was the largest marine reptile to have ever existed. They grew to around 60 feet long and weighed
around 75 tons, which is a comparable size to a sperm whale, and almost the same weight
as a blue whale. Their name means ‘Mount Shasta Lizard’,
after the mountain in California where they were first discovered… but the most interesting
thing about the Shastasaurus was its unusual structure. Their tails were far less developed than other
Ichthyosaurs, and arched downwards. Rather than being able to reach high speeds
during a pursuit, it’s more likely that they kept at a constant swimming speed, and
hunted opportunistically- catching any prey that crossed their path. In a similar way to the Shonisaurus, Shastasaurus
didn’t have teeth either, not even when they were young. Researchers believe that this short, toothless
snout, means that it was a suction feeder, and would only have eaten soft prey, such
as fish and squids. Thanks for watching!! Which one was your favorite?? Let me know in the comments below!! Remember to subscribe and see you soon!!

Author Since: Mar 11, 2019

  1. Your voice sounds exactly how British people make their voices sound when they take the piss out of the American accents.

  2. What the?!?! Today I reached 666 followers on #Twitter & now I'm seeing 666 everywhere! This video has 666 views at the time of writing this post. #TheTwilightZone

  3. Katrina!!!๐Ÿ˜„๐Ÿ˜I miss you been waiting for new videos and your appearance… Love from the Philippines!

  4. Your beautiful ๐Ÿ˜™๐Ÿ˜™๐Ÿ˜™๐Ÿ˜™๐Ÿ˜™ and your knowledge is excellent ๐Ÿ˜Š๐Ÿ˜Š๐Ÿ˜Š

  5. Scientist can be some of the dumbest people.. teeth don't fall out just because you don't need them lol ๐Ÿ˜‚

  6. I appreciate you working on your pronunciation…the videos are obviously researched and give lots of accurate information (many videos of this type don't even try for accuracy) but the mispronunciations just grated on my OCD.

  7. "Hi its Katrina" is perhaps the best intro of any YouTube videos. I noticed most of the prehistoric reptiles have similar elongated snouts of today's crocodilian species.

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