Evolution leads to the darndest
things sometimes! Animals like Stegosaurus and Dimetrodon are really very strange when you think about them And if we only knew the Platypus from the
fossil record we'd probably think it was some kind of joke. But these
adaptations didn't happen just for us to be amused by them millions of years later.
Even the strangest adaptations help an animal fit into its environment to get
food, make babies, and survive. You might think a platypus looks weird, but it's mom
probably think it's very handsome. The same was true for these ten prehistoric
animals: they might have been incredibly odd, but they were also incredibly
well-adapted to their environments. Helicoprion is not only a candidate for
weirdest fossil ever, but also for most enduring scientific mystery. The 270
million year old fish was first described in 1899 based on its buzzsaw-
shaped whorl of teeth and nothing else. Paleontologists figured the teeth belonged
to some kind of shark, but beyond that they were at a loss. They didn't even
know where to stick the tooth whorl on the fish's body... the end of its nose? the
dorsal fin? the tail? Eventually they came to the conclusion
that the teeth belonged in the jaw which is where you generally find teeth, but
they still had no idea how the weird looking to spiral was oriented or how
the helicoprion used it. Then in 2013 researchers at Idaho State University
turned their attention to a helicoprion tooth whorl with some of the
animals' jaw cartilage preserved around it. The fossil was discovered in 1950 and
left sitting in a museum for a while. Scientists had waited until 1966
to formally described it but even then the cartilage seem too mangled
to be informative. Then CT scanners and computer modeling came along. Using this
technology the researchers decided the whorl must have fit at the base of the
creatures' jaw. They also found that helicoprion isn't quite a shark it's a closer relative to ratfish and
chimaeras, the type of fish not the mythological creature. But how on earth
would a wheel of teeth be useful? Well probably the same way a saw would be
useful. Helicoprion probably fed on soft-bodied organisms like squid. That
round jaw wouldn't exactly spin like an electric saw but it would rotate a little bit as the
animal closed its mouth, catching prey on the teeth and dragging them inside.
Quetzalcoatlus was a giraffe-sized pterosaur named after an Aztec god. This
huge flying reptile from the Cretaceous period, between 65 and 145 million years ago,
had a wingspan of more than 10 meters! It seems to have evolved the ability to walk
on its front legs again and even after its pterosaur ancestors
evolved flight. So it walked on his front feet but its last digit stuck out with
the tip of the wing hanging off of it. Fossil remains of Quetzalcoatlus are pretty
fragmentary. We know that it was a pterosaur and we know that it was big.
But how big it was, what it ate, and whether it could fly are still open
questions in the pterosaur world. It's hard to know how heavy a pterosaur was,
because their bodies would have contained air sacks to make them lighter.
That means without more complete remains, we don't know how much of it was tissue
and how much of it was air, which would have affected whether or not it could fly
or if it had lost the ability to fly, like an ostrich. It might have used its
walking ability as a terrestrial predator and scavenger, or it might have
skimmed along the water and caught fish in its jaw like a pelican. It had a very long
neck, but it wasn't very flexible. It was probably best suited for sweeping along
the ground and snatching prey. Without more fossils, it's hard to know much
about the ecology of this thing and why a carnivorous flying reptile would have
had the approximate proportions of a giraffe. Imagine a toothless dinosaur covered in
feathers... now give it a huge pot belly... and now imagine it with burly forearms
and meter-long claws that make it look like Edward Scissorhands. You might think
this could not possibly be real but what you're imagining right now is
Therizinosaurus. Therizinosaurus belongs to the group of dinosaurs called theropods, which also includes ferocious meat-eaters like T-rex and Deinonychus. But
this Cretaceous misfit was a plant-eater. It was big enough that it could probably
sit on the ground next to trees and use its claws to reach up and strip off
vegetation. The big gut might seem out of place but it's the best practical way to
digest plant matter--that's why cows and manatees have a similar big-bellied look.
We don't know for sure why its claws were so long but therizinosaurus' odd
proportions would have made it very slow. So in addition to using them to slice
off vegetation, it may have needed them to fend off predators and the giant arms,
so different from a T-rex's, probably for holding up the claws. Microraptor was a very small dinosaur, as
you might have guessed from the name. Evolution didn't take a straight or
simple path from dinosaurs to birds, and Microraptor, another Cretaceous dinosaur
that lived about 125 million years ago was one of
the more interesting detours. Tiny dinosaur, the size of a crow, Microraptor had glossy black feathers, it
couldn't fly, but it could probably glide using its four wings. Dinosaurs evolved
feathers before flight, at first these feathers were simple fuzz later on they became asymmetrical in
shape to accommodate flight and Microraptor had these asymmetrical
flight for theirs on both its arms and legs, effectively giving it a
second pair of wings. Which seems like a lot of wings by the standard of today's
birds. But Microraptor probably used the second set of wings as stabilizers,
spreading them out to make a kind of second airfoil. Other lineages of birds
evolved more efficient two-wing designs, so the four-wing models became obsolete.
Glyptodon was a giant relative of armadillos, except unlike the small
flexible armadillos of today you can be excused for mistaking a Glyptodon for
a Volkswagen Beetle. These animals from the Pleistocene, about 12,000 to 3 million years ago, had a huge dome of armor covering most of their bodies, as
well as additional plates on their heads and tails. Some species even had tail clubs. So much
protective armor might seem like overkill, but fossils of Glyptodon have
been found with holes in their skulls, holes delivered by predators with giant
teeth. So when your neighbors are saber-toothed
cats it seems you can't have too much armor. We often refer to Glyptodon as a
giant armadillo and they were related but Glyptodons and armadillos as well as their relatives the Pampatheres are distinct evolutionary lineages so
Glyptodon wasn't really an armadillo more of a separate sort of car tank
thing it looks like a camel with a trunk but macrauchenia isn't closely related to camels or elephants, it belongs to an extinct group of South American mammals
called litopterns which died out at the end of the last ice age twelve
thousand years ago. Litopterns are technically ungulates meaning they're
related to things like antelope and camels but distantly. It might look a
little silly but macro Kenny's adaptations allowed to take advantage of
any plant food came across the trunk was good for plucking leaves and branches
and its teeth were shape for grinding tough grasses these adaptations allow it
to spread throughout South America and outlive all the other litopterns,
possibly even outlasting the ice age I guess it was worth looking a little
strange if it meant surviving this next animal
actually is an elephant and it's a pretty outlandish variation on the
elephant body plan, but platybelodon, an elephant from around eight to twenty
million years ago takes the cake. It had tusks and a trunk like a modern elephant
but it also had this huge scoop shaped lower jaw with a second pair of tusk. This animal has suffered from bad reconstructions over the years
paleontologist used to give it a wide flat trunk to match its shovel shape
lower jaw but according to more recent research it had a relatively normal
looking trunk and that's the secret to what it's weird mouth was actually for.
That lower jaw wasn't used for chewing. The broad teeth show signs of wear right on the front edge so scientists now believe
it would grab hold of grasses with its trunk and use the teeth to saw it off. Voila! Instant both grass meal, no dirt
included. The internet loves sloths, they're just so slow and cute and small,
but they weren't always small. Those cute little guys that live in the treetops
used to be earthbound grazers. Megatherium was a ground sloth the size of an
elephant it lived between 12,000 and five million
years ago like the therizinosaurus we talked about earlier it used its large
claws to reach up and pull down vegetation that would have been out of
reach to other animal it may also have used them to dig up roots. The claws
meant Megatherium couldn't walk very fast on its front feet so like therizinosaurus it would have
been pretty slow but it was also so big that most predators couldn't get their
teeth into it so it didn't matter you can just plot along and feed as
slowly as it like I guess that's one thing Megatherium and modern sloths have
in common. If you're not a fan of creepy crawlies you're not gonna like this one. Arthropleura was a millipede that could grow up to two metres long and half a
meter wide. That is longer than I am tall luckily we know from it's fossilized poo
it was probably a vegetarian if you're wondering what possible reason a
millipede could have to grow that big, well, it was probably so big it didn't have
any natural predators and like other arthropods a category that includes
insects and spiders and crustaceans it was able to a bigger during the
Carboniferous period 302 to 360 million years ago because back then earth had a higher percentage of oxygen
in its atmosphere arthropods don't have circulatory systems like we vertebrates
do they need oxygen to diffuse through their bodies instead. When oxygen is
scarce, that requirement keeps them relatively small but when there was a
lot of it here come the giant B-movie bugs!
Animal life was just starting to get a leg up in the Cambrian 485 to 540
million years ago that meant some seriously strange body
plans and new predators at the top of the food chain. Anomalocaris, a name that
means "weird shrimp," fit both of those descriptions. It's related to modern
arthropods though it's hard to tell how closely. To give you an idea of how
strange this thing is paleontologists saw different parts of
this creature and described them as a shrimp a sea cucumber a jellyfish or a
jellyfish on top of a sponge but all those fossils belong to just two species
of arthropod not half a dozen kinds of smaller species with it's big eyes and
grasping mouthparts they now figure anomalocaris was a major predator in the Cambrian seas. It
probably snacked on trilobites. It could reach a meter in length, which was
gigantic by cambrian standards. In fact, it's the biggest predator known from its
time. You don't really see these adaptations anymore because the
environment has changed over time. They help these animals survive in a
situation that no longer exists but the fossil record has preserved them so we
can now see how animals used to get by in all these useful ways even if they
do seem very strange. Thanks for watching this episode of scishow brought to you
by our patrons on patreon. If you wanna help support the show just go to
patreon.com/scishow and don't forget to go to youtube.com/SciShow and subscribe. [preview] --and each year we're discovering new amazing species that are
most at home in the ocean depths. These are eight of the strangest deep sea
creatures we've discovered just since--
