Despite their long existence and diverse adaptations, non-avian dinosaurs never evolved into fully aquatic species due to a combination of ecological competition, reproductive limitations, and anatomical constraints, unlike other animal groups that successfully colonized marine environments.
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Dinosaurs, a topic I'll probably never
get sick of talking about. And every day
I find myself pondering about these
terrible lizards, especially when I
probably shouldn't be. And recently, I
was thinking about something that most
dino lovers will eventually question,
which is, how come there was never any
fully aquatic dinosaurs? Now, if your
first thought is there was, then I can
say with certainty that you are a dino
normie. Because in reality, anything you
think is a water dinosaur is not. Not
this, not that, nor even these. And for
the most part, what people think to have
been water dinosaurs were in reality
marine reptiles who were not very
related. No, in the entire history of
dinosaurs, we are not aware of a single
fully aquatic species. And to me, that's
very strange when you really break it
down. I mean, here are the facts. This
group has been around for over 233
million years, had a long stint as the
top dogs of the planet, lived on every
single continent, Antarctica included,
widely varied in size, achieved flight,
and all combined are responsible for
well over 10,000 species. And yet, none
of them made it to the water full-time.
Meanwhile, other groups like mammals
have gone terrestrial, airborne, and
fully aquatic despite being around for a
shorter amount of time and being less
diverse when birds are included. So,
what exactly gives? Why did dinosaurs
fail to overcome this so-called barrier?
And to answer that question, it might be
best to actually start with how close
they came or come. And looking at birds,
even just the extent ones, we can see
that they're not really that far off
with there being many kinds of what are
called water birds, which are
essentially any bird that lives on or in
water for a large part of their lives.
And this includes some classics such as
pelicans, ducks, swans, gouls, the list
goes on. And across the board, we can
see that certain adaptations generally
take place with the most common traits
being legs adapted for diving
underwater, extensive webbing between
the toes in order to increase surface
area, and then changes in beak
morphology to adapt to more watery
diets. And among this group, you can
break things down even further through
the sea or marine birds, who, as their
name puts it, are those that have become
adapted to marine environments. And like
water birds as a whole, they greatly
vary in niche and specializations. But
again, we do also see some interesting
features that are widespread, such as
salt glands, which are located in their
beaks and help them expel excess salt,
allowing them to both eat and drink
really salty stuff. And some have even
given up on flying in exchange for being
great swimmers, like of course the
penguins, who do spend half their lives
in water. But again, half is not 100%.
And then on the other side, there are
those like the great wandering albatross
that still fly and are really good at
it, but simply live on top of water for
much of their lifespans, not landing on
land for sometimes years apart. Yet
again, they don't do this full-time, and
they live on the water, not underwater.
An important distinction. And so, do
they count as water dinosaurs? I think
not. And while all the modern lineages
of seabirds evolved after the KT
extinction, there were also Cretaceous
groups of them, like the Hesperorniths.
So, in other words, they've been a thing
for a minute. And while coming close, no
cigar. So with that out of the way,
let's take a look at the more
interesting group. No offense birds, the
non-avian dinosaurs. And while the vast
majority seem to be averse to the water,
there has actually been a handful of
species and families who were actually
pretty good swimmers. And in some cases,
possibly even semi-aquatic. Of course,
the best known group that fits the bill
were the Spinosaurids, a cateor of
usually large therapods that honestly
could have passed for crocs and legs
thanks to their odd adaptations. Now,
each differed a bit in their own way,
but some strong signs that this lot like
to be in, or at least around water,
included nostrils situated far back
along the skull in order to avoid water
seepage, cone-shaped teeth that were
suspiciously well-designed for catching
slippery fish, and in certain cases,
unusually large and powerful tails that
could have possibly assisted in
swimming. And get this, at times these
tails are only loosely connected to the
rest of the body, a trait not seen in
other dinosaurs, but rather in fish.
Furthermore, isotopic analysis and the
simple fact that most bones are found in
regions with abundant water reflect that
this family didn't stray too far from
aquatic sources. And therefore, we know
spinos were unusual, but there is still
a lot of debate about just how much time
they really spend in water, with some
saying they only stuck along the coasts
and waited, whereas others argue that a
few would have been semi-aquatic
creatures. And while Spinosaurids have
definitely taken the reigns as far as
representing the dinosaurs in the water
Olympics, there are actually other
interesting less reported cases of water
loving dinos. Take the Housecar for
example, a late Cretaceous non-avian
dino from Mongolia that as far as we can
tell was a dramas. Think Velociraptor,
albeit even smaller, with most being the
size of a malard duck. And it possessed
various anatomical features that you
would not expect to find on a raptor,
namely small forlims that were
flipper-like. And you know what flippers
are good for besides dancing? Swim.
Swim. Additionally, the skeleton also
possessed a short tail that shifted its
center of gravity to the front, which
makes it more useful for swimming than
walking. While it then also had a long
neck and sensory neurons concentrated in
its snout, presumably being there to
help it feel for vibrations in the water
and thus leading to the idea that this
was a fish eater. Something that was
also backed up by its teeth, which are
curved backwards and highly numerous. In
other words, being designed to help trap
small fish caught within. And another
thing that is commonly agreed upon is
that mother nature is struggling.
Animals are going extinct left and
right. I mean, we're literally in the
middle of a mass extinction event called
the holosene extinction, also known as
the anthroposine extinction, which if
you couldn't tell from the name alone,
is caused by, yeah, yours truly, us.
Which is why I'm happy to be partnering
with my friends at Planet Wild again.
And if you missed my last shout out,
Planet Wild is basically crowdfunding
for conservation. They choose a new
partner every month aimed at protecting
animals, forests, and oceans and backed
by a community of around 13,000 members
whose contributions are used to support
these projects. And the best part, the
community gets to see exactly how their
contributions are used in monthly video
reports here on YouTube. So, they're
100% transparent about where their funds
go. And a recent project which I know
would be near and dear to the heart of
any water dinos is rescuing baby seals,
another marine animal group. Of course,
in case you didn't know, gray seals are
in trouble. Rising temperatures and
storms are destroying the ice they
depend on to give birth, forcing mothers
onto unstable ice or land, where the
pups then easily get lost or stranded,
causing many of these young seals to
drift alone for days before washing a
shore weak and starving. And to help,
the Hell Marine Station in Poland
rescues and rehabilitates them. And with
Planet Wild support, they've expanded
their rescue center, built new
enclosures, upgraded their monitoring
systems, and added tracking devices to
study how the release seals fare in the
wild. And guess what? It's working. And
if you want to see more, I'm leaving the
link to the video report in the
description. Now, I have been a member
for a while, and I think it's a great
way for individuals to get involved in
conservation. So, if you want to protect
mother nature, I highly recommend
signing up. You can give whatever
amount, big or small, as every dollar
counts. And don't worry, you can cancel
at any time. And because I truly believe
in what they're doing, I will cover the
first month for the first 100 people
that sign [music] up using my code
extinct 111. So if you want to help save
the planet, scan the QR code or click
the link in the description to join. And
in Cretaceous Mongolia, you could find
even more critters similar to the
houseaptor as it was actually part of a
cate full of close relatives with
similar adaptations. A catey named the
houseaptor which collectively possessed
at least five different genre all from
Lake Cretaceous. And seeing that these
guys were raptors, they just like the
spinos were therapods as birds are too.
And so this group definitely seems to
adapt more towards water than other
dinosaurs. But that being said, there
are non-therropod cases as well. They're
just a bit more rare. And one of the
more interesting examples involves an
iguanadant of all things, the
lurosaurus. This creature lived during
the early Cretaceous about 112 million
years ago in Niger. And it name
translates to heavy lizard. And this
naming can be at first a bit confusing
because despite adults measuring up to 9
m or 30 ft in length, this guy was a
short king with its stomach essentially
touching the ground. And yet somehow it
still weighed 5.5 tons, making it
suspiciously heavy, hence the name. And
the implications of its weight goes
beyond what it's called. For along with
being heavy, it also had an unusually
stocky body plan that was somewhat
reminiscent of a hippo and therefore
leading to the idea that this was a
river adapted dinosaur that spent its
time near and in water for much of its
life munching on that oh so sweet
freshwater aquatic plants. Now, I will
say that this hypothesis is definitely
not confirmed. And the same can be said
about yet another dinosaur, the Leo
Ningosaurus, an Encyosaur that I dare
say is even more bizarre than our
guanadant and coincidentally lived
during the same era, just in China
instead of Niger. But unlike our heavy
guy, this guy was a little guy, much
unlike the iconic Encalosaurus, being
closer in size to a dog or cat than even
the average dinosaur. And opposed to the
later Encalosaurus, this creature was
also without a tail club knob and had
basically zero osteoderms or armor
plates besides in just a couple of
areas, which is, let's just say, quite
odd for an Acalyosaur. But this fact
might have been due to its unlikely
affinity with water. You see, when
examining its remains, paleontologists
noted a couple of things. One, that it
had a shellike structure that reminded
them a bit of a turtle, and two, that it
lacked the fusioning of its spine and
hips, something which typically acts as
support for an animal that is walking.
emphasis on the walking part. And this
alone was pretty interesting to the
team. But what was a bit more startling
was that the teeth were weirdly sharp
and almost seemed carnivorous in nature.
Oh, and uh there's also the fact there
was a fish in the area where its stomach
should have been. Signs that imply that
it could have very well been
semi-aquatic. So evidently some strange
stuff seems to be going on with the
Senkyosaur. Well, at least I thought. As
interestingly, just a few weeks after
having researched this, I discovered
that just recently, like in the last few
weeks, a new study has come forth
clarifying that in reality, what we
thought to be Leoningosaurus was in fact
just a baby and kyosaur that drowned.
So, uh, who knows? Also, rip. Anyways,
with the Leoningosaurus out of the way,
you still get a fair idea of how
non-avian dinosaurs did dip their toes
in water, but also at the same time
never managed to fully close the gap to
become fully aquatic, similar to what we
get with birds, which thus begs the
question of why. And it's not that they
necessarily couldn't like there was some
advent of evolution blocking them, but
rather that there was quite a bit of
obstacles in the way. And one big
roadblock was something totally out of
their control, competition. You see,
whenever you want to get into a niche,
you got to first make sure there's
enough room for you to fit. And during
the Mesazoic, there really wasn't that
much wiggle room when it came to the
waters. When the earliest dinosaurs
appeared on land during the late
Triacic, there was already the
ichthyosaurs rampant in the oceans who
were not only predatorial, but could be
found in just about every size. And then
on top of that, you also have the Sarup
Terriia, attacks on diverse dapsided
reptiles, which at that point consisted
of the aquatic nothosaurs, placadons,
and more. [music] While in fresh water,
carnivorous amphibians, fish, and
phytosaurs were just a few of the
problems the potential water dinosaurs
would have had to deal with. And so
without many adversaries, it didn't
really make much sense for dinos to try
and take over the water. Rather, just
made more sense to double down on land.
And this barrier of entry, so to speak,
only intensified as the messoic
progressed with animals beneath the
waves evolving, diversifying, and simply
put, becoming more terrifying with
plesiosaurs, mosasaurs, giant fish, and
large crocs all becoming stark
realities. Realities that in some cases
were even bigger and batter than the
predators the dinosaurs cooked up, which
is uh saying a lot. So, not a whole lot
of motivation for them to get their feet
wet, and I don't blame them. But it
wasn't only other animals that kept them
from taking a dive. It also involved
them as well as it was the design of
dinosaurs that was another major hurdle
in going fully aquatic. And one of the
main issues seems to have to do with a
reproduction. Now all dinosaurs are
arcosaurs which is a caid that contains
thing like birds, non-avian dinosaurs of
course, crocs, terasaurs, yada yada. And
what one will notice when scouring these
arosaurs is that the vast majority of
them if not every single one of them are
something called oipus. essentially
meaning that they lay eggs outside of
the body. And when you realize that the
vast majority of fish are vaporous, too,
in fact, 97% of them, you'll probably
think that dinosaurs would thus make the
perfect candidates for water. Yet, a key differences
