You're listening to Weird and Dead, the paleontology podcast
that tells evolutions most embarrassing and bizarre
stories. I'm Megan Weatherill.
And I'm Amy Atwater, and we are two living scientists who are
weirdly excited about dead things.
On this episode, we talk about sexy diarrhea, eating your own
puke, and how dinosaurs got so swollen.
Or really, we talk about how to get big and the things that are
holding us back from getting big.
Evolutionarily, of course. And clearly given the mention of
bodily fluids, you might not want to eat during this episode.
So check out the warnings in the description or proceed at your
own risk. For this episode, you should
pretend that I, Megan, am weathering out a Blizzard and
Yellowknife and not that I just messed up which microphone I was
recording on. No, I am at sea suffering
through the Drake's passage or something very cool.
That explains why I sound so very bad.
Sorry, let's talk about hippos, and specifically hippos sex
lives, because bizarrely enough, that does play into the
conversation today. So hippos.
Hippos are deeply into poop play, which is disgusting, but
also kind of a necessity because they have so much poop to give.
And that poop is not solid. It's more like a loose butt
gravy consistency at best, perfect to make the best of a
very bad butt situation. These male hippos will use their
tails like little shit flinging helicopters to spread all of
that, I guess attractiveness around to females.
And somehow that does work because we still have hippos.
So if you ever look up a video of hippos shitting, you'll see
poop, poop, poop, poop, poop, poop.
That's the sound of their helicopter tail.
It does say poop, poop poop, duh.
They are nasty. They are super, super nasty.
And there is a reason actually for that level of diarrhea,
which is going to be a big part of today's conversation.
Hippos are one of the largest land mammals today.
They can be up to 16 feet long, which is approximately 3 Megan
units, and they are about 1 Megan unit in height.
Pretty much exactly. I guess the maximum height of a
hippo is about 5 foot two, which is what I round up to.
Perfect, right? Yeah, adorable.
And they weigh up to about 10,000 lbs.
And I'm not going to tell you how many Megan's that is, but
it's a lot of them. So they're huge, they're huge,
and they are aquatic, or at least semi aquatic.
They're not trapped like whales. They haven't made that dumb of a
decision yet, but even though they are aquatic and they are
living in the water, they actually eat grass on the side
of their little rivers and lakes always at night as if they are
embarrassed by it. But there is a strong reason as
to why they live in the water and it is not because they are
eating aquatic plants because they don't do that.
They basically have to live in their toilet because you would
also live there if you had to. Shit 24/7.
I want you to imagine having food poisoning all the time.
Would you leave your bathroom? No, no.
No, no, you would not. Honestly.
They have to have frequent access to water because they
have to stop themselves from dying of dysentery.
Yeah, they're like mega dehydrated, I'm sure.
Yeah, they have horrible diarrhea and so they are
constrained to live near water as a result.
And this is what is known as a biological constraint.
It is the topic of today's episode.
Go home evolution. You're drunk.
I feel like that is like a major theme going on today when we
talk about organisms, how big they can get, how small they can
get, and why they are constrained to those
limitations. Like you said, biological
constraints are you know, frequently like morphological
factors or physiological things that limit to how an Organism
can evolve over time, right? Like evolution again is not an
an inventor. If we're talking about how
evolution works, evolution has to work with what is already
present in the Organism. So we like to think of evolution
as more of a tinkerer and less of an inventor because you got
to work with what you got. Personally, having just given
birth, I'm thinking a lot about biological constraints because
of how horrible it was to give birth.
So that is a major biological constraint of humans is our
giant heads and our tiny pelvises.
All right, so let's talk about giant, giant, giant land mammals
now. Hippos are quite big.
They are very, very far from the biggest land mammals.
You'll notice I'm using the word land very carefully.
Fuck whales. Whales don't count.
Whales are fully in the water. Whales eat whatever the fucking
krill and bullshit they do, so they don't count.
They're a totally different set of biological constraints.
They different. Podcast episode.
Exactly. Talk about them later.
Yeah, they went back to the ocean and they're not involved
in here. But for the biggest land mammal,
it kind of depends on who you talk to, because again,
estimating the mass of these animals is ridiculous and gives
you very wild estimates. So one of the biggest ones
probably I think the biggest one just because I want it to be the
biggest one would be Indrikathirs.
So Indrikathirs were like if you took a giant giraffe and then
reskinned it as a rhino. That's an indrikathir.
The genus is Paraceratherium is the the genus name.
But yeah, they're just long ass rhinos and they got to be huge.
The estimates I've read were potentially up to 24 feet tall.
I'm not even going to tell you how many megans that is because
it's a lot and up to potentially 40,000 lbs.
So you know, just a little. That's just four hippos just
stacked on top of one another. Actually, that wouldn't be tall
enough. You need another hippos worth of
height. Hippos are chunky, so very, very
big animal and it is related to rhinos and horses.
And then the next close contender is an elephant
Paleoloxadon. Some people think it might have
come in a little heavier at 44,000, but does not.
And he's smart. So, yeah, we.
Listened to him. Yeah, so I don't think it really
was that big, but it was probably pretty big and it was
about 17 ish feet tall, so pretty big.
And then there's the biggest ariadactyl.
So we've got elephants that are giant, we've got horsey rhino
way things that are giant. And then we've got the cool
ones, which are things that are related to cows and deer and
pigs and camels and giraffes. And the biggest one there as far
as weight goes is hippos. There's an old hippo that's a
little bit bigger than a modern hippo.
It's like 10 percent, 20% larger because that's really the the
biggest that artiodactyls can be because of this biological
constraint. It's not embarrassment out of
shitting themselves constantly, it's because shitting yourself
constantly has some some problems associated with it.
But Despite that, it's actually kind of a good thing.
So this is not like an ad for Activia, but shitting yourself
is awesome by my diet tea. When we talk about big
orbivorous land mammals we are usually talking about kind of
two different styles of digestion.
I like to call them the tum tum crew and the bum bum because you
have ones that have four gut fermentation.
So they ferment and do all their weird shit at the start and you
have ones that do hind gut fermentation.
They ferment and do all their digestion.
At the end artiodactyls, things like cows and hippos.
They have a four chambered stomach and that four chambered
stomach is where they do the vast majority of their
digestion. Then they pass everything
through their intestines and the intestines in the colon are what
pulls water back out. So that's why they have
diarrhoea, especially if they get really, really big.
They have diarrhoea because the the pulling out of the water
part is at the very end and usually they don't have a lot of
room for it because they have these massive 4 chambered
stomachs. Whereas when you're talking
about like Paraceratherium, you're talking about rhinos and
horses and even elephants. They're part of the bum bum
crew. They have invested more of that
nasty ass fermentation shit in their butt region.
So in the back half with cows as your kind of classic adiodactyl,
they do fermentation first. Bizarrely, that is with
bacteria, not with yeast. So they're not getting shit
faced drunk all the time, but they do swallow their food very
quickly as it turns out, and they ferment it you.
Would know, yes. And then they frequently puke it
back up and then chew it and then swallow it again.
So they've got like the fermentation chamber is at the
front and then they have the acid chamber, which is what you
and I have, that we don't have that fermentation chamber,
despite how gassy we might be. We really only have that
hydrochloric acid stomach, You know, cows have that too.
It's just the secondary step. And the reason that that is
great is because fermentation is done by bacteria.
But once the bacteria finish their job, they often get passed
back to the stomach of acid, They die and are digested by the
cow. So animals that have
fermentation that starts first are usually more efficient
because they can digest their microbes.
Whereas animals like horses, they have their stomach first,
they have that acid bucket 1st, and then it goes into a smaller
fermentation chamber. Not as complicated as a cow's.
I think it's only like one or two chambers.
That's nothing. And so horses do fermentation
second, which means that all of the bacteria that are in that
fermentation chamber get passed right out through the butt.
No nom noms, so having that 4 chambered stomach is actually
really advantageous for artiodactyls.
It means that they can digest really shitty ass food way more
effectively and efficiently. They can live for longer on less
food. However, that 4 chambered
stomach is huge, so it often does not leave a lot of room for
a colon. And the bigger the animal gets,
the less room you have, in part because you don't want to have.
You have to move your food really, really fast through your
stomach, because otherwise you will build up methane and you
can, you know, I don't know, explode.
I didn't actually look up the consequences of that.
But I'm going to go with explode.
You can explode, obviously, or at least get very, very bad.
Stinky Super stinky too. Yeah, so as an Rd. dactyl gets
bigger. They have to process their food
a lot faster to avoid, I don't know, becoming a cow balloon.
And so they're passing things through so quickly that the
parts of their stomach and their colon, which are already smaller
than in a horse, that are designed to take the water out
of that food, basically don't have time to do it all the way.
So artidactyls have a size constraint, they cannot get
nearly as big as perisodactyls. So horses or proboscidians,
things like elephants, which have a reverse system that
focuses more on water, they can take out a lot more water.
So horses might need more food than cows do, but they need less
water than cows do. But evolutionarily, honestly, I
think most modern domesticated horses are just kind of you look
at them funny and they get sick. So if we're talking about like
natural wild horses, not not the weird ones everybody keeps
inbreeding. Well, do you think that there's
any reason behind like we have way more artiodactyls alive
today than we do Pericodactyls? Like we only have what, three
groups of living pericodactyls, horses, dry nose tapirs, whereas
artiodactyls are everything else with a hoof pretty much.
So do you think that? I mean, would would you think
that GUT influences this that like there are they're being
more efficient is an evolutionary advantage too, even
though they can't get that big? I would imagine so.
Maybe they can't get that big, but they can sustain themselves
on pretty low quality forage like grass.
Grass is gross. Animals have evolved to eat
grass, but it's not because they fucking wanted to, because that
was all there was. Evolution is not a choice you're
forced into. It or do you die?
We see a rise of ardiodactyls and a decline of things like
horses and elephants as we see kind of that increase of grasses
and grassland expansion. So yeah, horses may have had
like, oh, their toes got smushed together and their teeth got
long. Well, ardiodactyls still do it
pretty good. So what if they shit themselves?
I was also going to ask you which one you'd rather be.
Oh, well, OK. I mean, I don't like shitting
myself. I'm sorry, cows.
I know that. I feel like I should be with
you, but if I had a choice, I'd rather have to drink less water.
That's that's mine. What about you?
Do you want to shit yourself or do I?
You know, we've talked a lot, and I don't know what order
we're going to do this in. We've already established that I
have IBS. Yeah.
So I mean, I'm already fairly used to that.
So I'm like cool with sticking with what I know and having an
efficient system. Stick with what you know.
Yeah, yeah, yeah, that's fair. That's fair.
Anyways, yeah, so sometimes your stomach can limit how big your
body can get. So that's the biological
constraint. We really kind of went way
around the way around the rosy, way around the bushes in order
to get back to that point. But sadly, diarrhea is not the
only biological constraint, and in fact, big bodies themselves
are not the only ones that have biological constraints.
Some small, cute animals also have to pay attention to
evolution's rules, Right Amy? Oh my goodness.
Yes they do. And this was mostly my excuse to
talk about tarsiers, because tarsiers are my favorite animals
ever. Yeah, we're going to talk a bit
about primates. Granted, there are really big
primates as well. Go ahead and look at gorillas.
Those are, yes, also very they, but they have their own
interesting constraints too. So we'll talk a little bit about
that. So essentially, primates are
very interesting and something I studied in school and I'm
fascinated with. When we try to reconstruct the
size of fossil primates, which is what I did a lot with Oma
Myads, which are Eocene primates that lived here in North America
and across the world that are closely related, would have been
more closely related to Tarsiers than any other primates.
Tarsiers are the very, very small primates that are found in
Southeast Asia that have giant eyeballs.
And I always say that they look like they've had way too much
coffee or something like that. Like, really?
Big guys, they look like they've experienced, like a lot of
trauma. Also like they don't just look
caffeinated, they look shocked. Maybe that's another reason why
I love them so much, especially. Because graduate.
School was especially traumatizing for me and maybe
that's why I related to the tarsier so much.
That's a really good point. But what's really interesting
with primates is it does seem when we try to interpret their
size, we can also say a lot about their dietary behavior
too, from again, their their size constraints.
And that's an interesting idea. And so it's referred to as Kay's
threshold. Richard Kay was the guy who
started articulated the Thoughts 1st and so the magic number is
500 grams. What this threshold goes into is
that it sometimes makes sense to eat essentially insects versus
leaves. So all primates are going to be
eating some sort of diet that consists either of an omnivorous
diet. That is going to be, you know, a
lot of vegetation, lots of leaves, fruit, nuts, seeds,
roots, tubers, those sorts of things.
And also, though in a lot of primate diets, being we are,
most of us are omnivorous, humans are primates as well.
Primates as a whole are consisting of lemurs, lorises,
tarsiers, monkeys, apes and humans.
And so right we're doing a lot of vegetation.
And then also there is a more carnivorous aspect or
insectivorous aspect where you might be eating a lot of
insects, though some primates are also eating eggs, some
primates are eating lizards, frogs, birds, sometimes even
other primates. Chimps are known to literally
hunt vervet monkeys as well as Bush babies.
Like they've been documented using like stabby sticks and
like stabbing them into tree wells to try and get out little
Bush babies and just have, like Bush baby kebabs.
I feel like that implies more that they know that they're
like, it sounds like they're good at it.
From the videos I've seen, it's more like they're kind of just
poking and hoping to hit something.
They're fishing with a stick. But why would they fit?
It's. Noodling.
Oh my God, Chimps are. Just noodling.
Just noodling for Bush babies. Noodling for Bush babies.
I heard it here first. Yeah, well, it it it gets
complicated when we try to establish what other species are
knowingly doing. However, we do have pretty good
evidence that chimps, like male chimps will get together and go
hunt and like murder other male chimps.
So they're the only other species besides humans known to
do premeditated murder. So I mean they are aware on some
level. So it does get pretty grim with
chimps. Anyway, we're so when we go back
to like why would a primate want to or why are there, why is
there this kind of magic number? And when you think about it, it
really does make sense if you are smaller than 500 grams.
If you eat a lot of insects. Insects are packed with
nutrients, tons of protein, tons of calcium, all sorts of
important stuff. They're trying to convince me
that I should eat grasshoppers. I have a hard time with that,
but for small primates it makes a ton of sense because they're
pretty small and they can literally eat them.
For bigger primates, after a certain point, it doesn't make
as much sense because they're so small and it takes a long time.
They're fairly hard to catch as well.
So a a larger bodied primate literally doesn't have enough
waking hours in the day to hunt enough insects to make it worth
the time to be a sustainable dietary option.
So what they do instead is have more vegetation in their diet,
more leaves, more fruit. And this also, when we talk
about leaves like you were just talking about, this is harder to
digest. You need a more advanced, I
guess, or detailed digestive system to be able to break down
this vegetation because of all the cellulose and all these
leaves. So you need this more complex
digestive process, and small primates are literally not even
big enough to maintain a constant throughput of that
leafy material. Like they're not not even big
enough to have the guts that would be necessary to process
that kind of vegetation and to really swallow that load.
So there seems to be a divide because of their body size.
Swallow that. That's disgusting.
Amy, you knew what you were doing.
OK, but to end the this primate segment, if we can include any
of it at all, there's one. I read this research paper from
2020 about 1 primate Megan who is not following these rules.
What? One primate, Megan, is always
doing something different and being fucking weird.
Is that the II? Yes, yes, thinking is giving me
the I I finger. Yes 'cause they are fucking
weird. They're the weirdest lemurs out
there and they are not following this rule because they are just
a little bit larger than the 500 grandpa.
And apparently they eat a diet that, as we know from those
creepy fingers that they're using to tap into trees and
whatnot to find grubs and insects, they're eating about
88% insectivorous diet. So again, I eyes fucking weird.
Amazing. Not appreciated.
We love them so much. So thank you I eyes for again.
Doing weird stuff with bugs. And you know, sometimes, of
course, it's not the primates or the organisms eating the bugs.
It is the bugs. Hey, you know what's not a
dinosaur? Everything on this shirt that
Megan made for her clothing store Geopedal fabric.com.
You can proudly sport your knowledge wearing the
Dynoposaurus shirt and spread the good word.
Enter code weird and dead at checkout for 10% off your order.
Like this episode? I hope so, because you have
listened to a lot of it. So if so, you should check out
more offerings on the Geology podcasting network, like
Backyard Geology, a podcast all about the amazing things that
people have found literally in their own backyard.
Yeah, bugs. Let's talk about bugs.
Let's talk about how sometimes they got really fucking big.
Like worryingly large. Like today's bugs.
There's some pretty big ones, and I'm not cool with it, and
I'm using bugs in the colloquial.
Since I am talking about both insects and arachnids.
I know that they're not bugs, and technically bugs as a
subgroup, but whatever. So today's insects and arachnids
and crustaceans and whatever, There's some big ones.
I don't know if you knew this, but there's some giant goddamn
crabs and lobsters. American lobsters can almost get
to a full Megan. They're 4 feet long.
Yeah. No, I mean, yay, is it biology
fun? Yeah.
I'm going to make a lot of during this section because me
and insects and crustaceans are not always best friends, so
we'll see how this goes. Yeah.
Now, of course, lobsters, much like whales, They're in the sea,
so they have totally different constraints.
But they can get pretty big land crustaceans.
No, not land crustaceans, land insects and arachnids.
I don't want to promise that I looked up crustaceans.
I got roasted out enough when I was looking at insects and
arthropods. So land arthropods, some of the
biggest ones were during the Carboniferous period, which is
about like 300 or so million years ago, and they got really
big. So Arthroplura is probably one
of the more famous ones. It was a big, I think it's a
millipede, not a centipede. I'll double check it later.
It's one of those two things, millipedes, they have thousands
of legs, but they're herbivores, Centipedes, they have slightly
fewer legs. They only have one pair per part
and they are carnivores. So it's one of the ones that has
too many legs and it's really long.
It's like a super leggy plated snake.
And these ones got to be more than a single mega.
They got to be pretty much an Amy in length.
They got to be about two meters long.
Yeah. So they were pretty tall, pretty
tall and lanky. Well, pretty elongated and
lanky. They didn't exactly stand.
That long don't thank God. They were not going to be
America's Next Top Model. They were only horizontal.
So we've got Arthur Fleur out. We've got things like mega
neuropsis, which was they look like dragonflies, but they're
not technically dragonflies. They're called Griffin flies,
and they got to be about the same size as a crow.
They had a wingspan of about 28 inches.
There was things like Homona Scorpius, which is a scorpion.
Weirdly, I think it's from Scotland and they were about the
same size, so crow length not a crow width.
Thank you for defining that. Honestly, I don't know if that
that measurement that I just did makes any sense, let alone when
you can't see me doing my own wingspan thing on the video that
Amy is watching. Regardless, Big fucking
arthropods on land. Fortunately those are no longer
around, but part of the reason that they were maybe able to get
so big and maybe are no longer able to get so big is a
constraint on oxygen. So body size, instead of being
controlled by how much diarrhea you have, it's how much you can
breathe. Arthropods have slightly
different respiratory systems than we do.
Insects have a series of tubes and the way that I saw them
described is you know that like stretchy tube with like ribs
that you use on like the laundry machine that like curves real
weird or like on a shop vac. Yeah, yeah, sure.
Yeah. Let's roll with.
This, yeah, Yes. So imagine that small and
snaking all the way through a lot of the body and that's what
you get for the respiratory system.
And they don't have lungs. They have a little bit of
muscular control, but it's more like if you wanted to take a
deep breath, if you had to like do a sit up, like they have to
use external muscles. There's not like a set of
muscles dedicated to trachea. So they have like passive air
transport essentially Spiders and scorpions have some similar
stuff. They also have that passive air
transport, but they also have like this bigger organ called a
book lung that does a little bit more of that.
But one big thing that all arthropods have is an open
circulatory system. So imagine this.
No, this doesn't make sense. It's like a polyamorous
circulatory system. It goes everywhere.
Like, it is not constrained by anyone, vein or artery.
It's all over the place. Yeah.
Insects don't have veins. They don't have arteries.
They just smushy smush that blood all around their body and
then just hope that it gets to the right spot.
So they actually don't do a lot, right?
Yeah. They're like a gusher.
They are. They're just like a gusher, just
like a gush, 100% delicious. As a result, they have slightly
different limitations on size because it's not the same
system. So with us, we have the lungs
and then it goes into the blood and then it gets sent to all the
places that it needs to go. With insects, it goes into the
trachea and it diffuses into the blood, but the blood has to get
sloshed around inside the bug in order for that oxygen to get to
different parts of the animal. So what this means is that as
insects and spiders get bigger, they have to have more and more
of these little trachea tubes, and they actually have to have
more than you would expect. So we were talking about like
isometry and olometry earlier, and how scaling is kind of
weird. Sometimes you can't just take a
bug and make it bigger and just make the tubes wider, especially
not with passive airflow. You need to have relatively
small tubes, and that means that they have to have more contact
with the rest of the body, so you have to have more tubes.
So as insects get bigger, they have to dedicate more of their
body space to tubes, which is part of why today we don't have
bugs that are just like walking around full of air tubes,
because it's it's just too difficult.
They'd they'd be like 90% air tubes if they were super big.
You're making a face. This is natural.
Well, just imagining bugs still this this big.
I just don't. I don't.
And I think you're getting, you're getting there about how
and why things were different in the Carboniferous that allowed
for them to actually, right? Like, I'm glad that the things
are not the same as the Carboniferous right now, for a
lot of reasons, yes. One big difference in the
Carboniferous is that the oxygen levels were different because at
that point bacteria were actually not very good at
breaking down wood. So a lot of carbon dioxide was
being pulled out and there was less.
When you're when you're like decomposing something, not you
personally, but like when bacteria do it, they also they
bring in a lot of oxygen. And because they weren't very
good at decomposing things, they were not burning as much oxygen
as they used to and there was a lot of plant life pumping oxygen
into the air. And so moral of the story is
today we have about 20-2 kilopascals of oxygen in our
atmosphere during the Carboniferous.
Estimates vary. It was somewhere between 30 and
35, so we would have probably all been a little bit stoned and
goofy if we lived during the Carboniferous.
Well, if we went back to the Carboniferous.
Then now that part of the Carboniferous I can get behind
that part. Sounds cool.
Right, OK, you want to be stoned and goofy and then see a six
foot long millipede? Bad trip sounds even worse.
So worse trip. Yeah.
So during the Carboniferous, because they had such high
oxygen, they didn't have to have quite as efficient of a trachea
system. So really when we talk about
constraints on insect size, a lot of times we talk about it as
it if as if it was oxygen that was the constraint.
It's not oxygen that's the constraint, it's the fact that
they can't be full of tubes. So if you have more oxygen, you
avoid that biological constraints.
But thankfully today we don't have that much oxygen, so the
insects are just fucked. They can't get that big.
Weirdly, one of the other reasons that we may not have big
insects today is actually not this biological constraint of
trachea size and open circulatory systems.
It's birds. Thank you, birds.
Right. So there's actually lots and
lots of very large flying insects that continue after the
Carboniferous. So they continue into the
Mesozoic with dinosaurs during a time when oxygen levels were
much lower than they were in the Carboniferous.
So these big Griffin flies, in particular crow sized crows,
crow wide wide crow sized dragonfly things.
These Griffin flies went extinct basically at the same time that
birds evolved either because birds were like yeah that looks
delicious or they were looking at the Griffin flies food and
saying fuck yeah that looks delicious and they out competed
them somehow. So birds thankfully are part of
the reason that we do not have giant giant giant flying insects
today. But weirdly some of bird's
ancestors had fewer limitations on body size it seems.
Yeah dinosaurs but why? So why so big?
Why? Why?
And I I know I was trying to think.
I was like, well, it's not really biological constraints.
It's like biological like fuck. The rules.
Fuck the rules. I'm going to be huge.
It's like why I'm better at this than everyone else,
interestingly enough. But yeah, I mean, and we we, you
know, we know that dinosaurs got stupid huge.
I could go at it with a bunch of stats about some of the biggest
dinosaurs, but I know half of our listeners know that
information way better than I do.
So I'm not going to bother too much.
But what we're going to talk about is, well, how?
How did dinosaurs get so stupid? Huge.
Why? How were they constrained?
If they were constrained, what allowed them to have this crazy
diversity of body sizes? I think I read in one of the
scientific papers I was looking at this week that the smallest
dinosaur and the largest dinosaur are like 20 million
times different in size. Like, God, there is that
disparity within dinosaur body size evolution, which is just
really, really, really interesting, Which is as nice as
I'm ever going to be about dinosaurs.
And I'm glad you were talking about the oxygen levels with the
insects, because some of the earliest ideas about why
dinosaurs got so big is that there is like, oh, there must
have been more oxygen around and they were just, like getting,
like, jacked on all of that oxygen.
Just getting swole off of. O2 I assume it's like the
opposite at living at elevation like I do here where we had to
go get the baby tested like right after birth to make sure
that he like had enough oxygen at 8000 feet.
So anyway, I can't. I guess sea level is just great.
So however, yeah, like we were talking about, scientists have
largely debunked this idea that there was more oxygen.
It looks like it was pretty similar to what the levels are
today. And then also, which I find this
really funny, folks also thought for a while that there was like
a lower level of gravity, like less gravity.
So they were able to just like, I love that idea of just like
did we like, slow down in our spin?
Did the Earth change size dramatically?
Like, you know, I I don't know enough about physics, understand
how this would be possible, but the Earth has generally been the
same size since the Mesozoic, because geologically it's really
not that long ago in terms of the Earth like the universe.
So the gravitational impact and pull is about the same.
So again, gravity, oxygen are remaining constants.
So how and why? And it looks like there are, you
know, morphological reasons behind this.
And it looks like there's ecological reasons behind this.
And then what I also found was really interesting that we'll
touch on at the end is how exactly, you know, not just,
like, what did your bones do and whatnot, but how did your
Physiology actually lead to this increase in size 2 with, like,
how did you grow, which is, you know, an interesting question on
some levels. I'm going to send you an image
from that figure from that paper too, because I think it looks
like a butthole because I have the maturity of a 2 year old.
All right, but let's talk about OK, if we're talking about big
ass dinosaurs, we're talking the biggest of the big, the biggest
land animals of all time are going to be sauropods.
OK, sauropods are long neck dinosaurs.
You know, everyone with their brontosaurus, whether or not
brontosaurus is a valid genus. Anyway, it's not nearly as big
as a lot of the titanosaurs, and those are the ones that are from
South America. I'm going to talk about
Argentinasaurus because when I lived in Atlanta, they had a
mount of Argentinasaurus at the Fernbank Museum where I worked
for a very brief amount of time. And it's thought to be again,
one of the largest dinosaurs that ever lived.
Because again, we didn't find all of this dinosaur, and we
didn't find all of the other giant ones like Patagon.
What is it? Patagonasaur.
Nope, that's not right. See we have.
To keep trying, keep trying, keep trying power through.
No, I can't. Oh, Dreadnotus.
Dreadnotus is another one of the really big boys and I don't even
want to try. I'm scared of Padigo Titan.
That's what it is. Padigo Titan.
God damn it, I hate dinosaur name so much.
Anyway, all of these guys are all thought to be like
contenders for the biggest dinosaurs that ever lived.
Argentinosaurus was thought to be again.
I love this mass estimate that literally is just on Wikipedia
guys. It's thought to be 110,000 lbs
to 220,000 lbs. So we're talking about a range
varies within 100, a £110,000. Well, you two imagine looking at
a person and being like they're anywhere between 150 lbs and 300
lbs. And I can't tell.
I don't know. Yes, exactly.
Y'all like, this is what we're working with when you're dealing
with fossils and when you're trying to extrapolate body size
from isolated. Anyway, it was thought to be
about 100 feet long. It could have been up to like
130 feet long. Maybe it was only like 90 feet
long. Again, we don't even know how
the bones are spaced. Anyway.
These guys were freaking huge though.
That's what's important is these dinosaurs were extremely big.
And how did they get so big? Well, there's a few things that
we're looking at. You know, they're just, I love
this. I was reading this and they're
like they walked on four legs and I was like, well, yeah, but
that really does play a role. When you're not constrained by
just two legs, you're able to put on more mass, you can
support more body Yadi Yadi with four legs than two.
And so that's why our sauropods get bigger than theropods, which
are meat eating dinosaurs that are generally bipedal now.
I'm pretty sure they're always bipedal and they are with with
their two legs, though they're not constrained by 4, they're
better at running. So again, it's all about like
trade-offs with evolution. And so sauropods, they've got
these four legs, their legs are also right under them and that's
important because like unlike a lizard or something like a
crocodile, they're actually able to support their body.
Adi adi again a lot more. And these limbs are essentially
pillars, like, they have just like incredible support because
of these thick, strong bones. And then we also have pretty
immobile joints. So you know, like we can do all
this like fancy shit with our wrists and ankles.
They don't do that. They're like, let's get these
super solid so that they can again support even more weight
on them and it also helps them disperse their weight well also.
Now, another thing that I kind of want to talk about with some
of the mammals too is this long neck phenomenon, because a lot
of the biggest mammals also have either a long neck or a long
trunk which allows them to reach more food, and it also allows
them. I love this laziness.
It allows them to stay in one place and reach food without
moving like more than other organisms.
And I'm like, that's hot. I never thought about the utter
laziness of a long neck for that sort of adaptation.
Now, this also ties into some of the ecological constraints,
right? So when you have an ecosystem
that has a canopy, right? So we've got trees that are
growing, leaves at different heights, and you might have
grasses. Probably not at that point.
Nope. Shrubberies.
Little bushes. And then we've got taller trees,
a lot of conifers. Some early angiosperms at this
point too. And if you have a long neck,
you're able to get to a part of the ecosystem that no other
dinosaurs are able to access. And so we I kind of think about
this with giant ground slots too, with their crazy long claw
hands, how they use those not to like, again, like murder each
other, but to actually get taller branches off of their
trees and whatnot. So again, like having this long
neck opens up a whole new part of the ecosystem for sauropods
to take advantage of and be able to also then eat lots of food by
staying in one place. What I find is also interesting
is that sauropods, it's not thought that they really chewed
their food, which is a difference from mammals as well.
That's also because they had gastro lift, so they had stomach
stones that help them digest and breakdown food as well.
But there's an idea that that also saves them energy by not
having to chew. And when you think about a cow,
like chewing all the goddamn time and then regurgitating
their food and chewing it some more, just for good treasure.
Cows. Cows sleep 4 hours a day.
They ruminate, which means they chew their cud.
They chew their own puke 8 hours a day.
Oh my God, could you imagine eating your own vomit twice as
long as you slept? Oh, I did.
Also because it's always confused me because, I mean a
cow where a sheep burp is not like a glorious smell, but it's
not vomit because it's coming from, I didn't get a chance to
say any of the four names, but they're such dumbass names.
It's coming from, like the reticulum of the stomach.
So it's not, it's not coming from the acid portion of the
stomach. So you're just getting like,
fermented stuff in your mouth. And it's because they don't want
to, they don't want to chew it as they're eating it.
It's more effective to shove it in, let the bacteria start
breaking it down into sugar and then chew it.
But poodoo, one of my sheep, I will take a video and send it to
you at some point. She's a hair sheep, so she
doesn't have like a lot of fur on her face and she will get
like, she'll just look at me dead in the eyes and just puke a
full fucking wad of like bubblegum size like just in her
cheek just and just staring dead eyed at me with no problem
whatsoever. Because yeah, I guess they like
the taste of their own puke. You'd have to, I suppose.
Right again. And this is where I'm I don't
mean to get on a just on a platform here and be like
evolution is true. But I I'm also like, come on,
what kind of sick fuck God is like, yeah, this is how it's
going to go. Hippos.
Hippos get turned on by their own poop and sheep get to eat
their own puke 24/7. This world is going to be wild,
yeah. And we didn't talk about it.
I think we'll have to get to it another episode.
But I also know that lagamorphs like rabbits.
They have a weird gut. System and they're.
Not able to fully digest everything, so they end up
eating their own poop a lot to be able to digest it and get the
new out of it. And again, I just see that and
I'm just like, hey like guys, evolution is true.
Like what weird Creator is up there like maniacally being like
and then this cute animal will eat its own shit?
It just doesn't. It doesn't make.
It doesn't make sense. You know, I just come on.
Evolution is again a tinkerer. You work with what you got.
It's good enough. It's not great.
Oh, gosh.
Wow. All right.
So sauropods, yeah. Another interesting thing that I
was reading about with the ecosystem aspect is some
scientists think that there may have been just lower levels of
productivity in the ecosystem in the Mesozoic and that there
wouldn't have been as much flora to support all the fauna and
whatnot. And that that could have led to
these animals getting much bigger because it allowed them
to have like, oh, and and like less actual dinosaurs that were
around too. Like within their population
there were less sauropods. And this would allow them to
just like hold on to their biomass and take a really long
time to digest their food and suck everything out of it.
Because there wasn't a lot of other options going on with
these low population and low just ecosystem availability.
And I don't know if I'm explaining that very well.
I have to read more about some of it because it was, it was
very, very interesting to just think that.
And then when I was reading about island gigantism, it did
kind of touch on those ideas as well as that.
If you get bigger, you can take longer to digest your food, like
a giant tortoise perhaps, and therefore you can go longer
between feedings as well. So maybe sauropods were able to
just like ride it out on their giant slow digesting stomachs,
which leads us into why were they able to get bigger than
mammals? Why are they better at getting
bigger than what we see in mammals?
And the slow, slow metabolism is a big, big part of that, That
they had these really big stomachs that allowed their food
to stay in their systems much longer and digest more and
therefore get more nutrients out of it.
And they weren't probably constrained by we don't know.
I would love to know about sauropod diarrhea.
Like come on, someone tell me if this is a thing, but we also
know that they are using gizzard stones, that they have these
gastroliths. So they're using these unique
ways to also go about using less energy to break down their food
as well. And then a really big one about
why they're able to do this better than mammals is because
they have more of a bird like breathing system and they also
have air sacs or pneumatized bones, especially in their neck.
I've seen sauropod neck vertebrae that are just full of
these really intricate pockets and kind of openings and
whatnot, and those are all allowing for air sacs to be.
They're allowing their neck to be a little bit lighter.
But it also helps them have a better, more efficient breathing
system where, like birds, they're actually able to have a
supply of oxygen in their system.
Even as they're exhaling, breathing out, they're still
able to maintain that oxygen. And again, talking about oxygen
levels, more oxygen allows you to be bigger A.
Lot of times too. It was fascinating to dive into
the Y instead of just less gravity, which again, I love
that idea. Do.
That and then I read this really interesting paper that came out
in Science this last year that was all about how did they grow
so big. Like usually biologically you
have two options for doing that. You can either grow faster,
right? So like early on like you're
going to go through a much faster growth spurt or you have
a longer period in which you grow, so you've extended your
growth time. So this paper actually they
looked at the bones of theropod dinosaurs.
So again these meat eating dinosaurs, so bipedal predators
that don't get nearly as big as the sauropods but still got
very, very, very large including bigger than some of these
biggest mammals. And they looked at how these
dinosaurs grow. And they created by looking at
the growth rings in the different dinosaur bones.
Through the paleohistology, they're able to figure out that
dinosaurs didn't really follow any of the rules.
T Rex did it one way. And then I feel like Spinosaurus
did it totally differently. Like, yeah, T Rex decided to
have faster growth rates. Like, they just got bigger
faster. And then Spinosaurus instead,
like extended its amount of time that had relatively slow growth,
but did it over a longer amount of time.
I'm even though none of them have like crazy long lifespans
either. So it's very interesting to
think about. Anyway, so dinosaurs are
fascinating, kind of, and it's interesting to go into the
ecological constraints of this. Then we're not going to dive
into it on this episode because we don't have time and we're
probably going to cut this down as is and make some bonus
content as well. However, we hear you all
screaming about island ISM and island gigantism and island
dwarfism, and we hear you. It's just too dense of a topic
to include in this. It does tie in to what we're
talking about and it does, you know, where you live does have a
lot to say about your constraints of what your body
can do. And we will be talking about
that because it's very interesting that a lot of times
small organisms that are small on the mainland, on an island to
get much bigger, like a lot of rodents.
And then also a lot of animals that are bigger in the mainland,
like artiodactyls and like proboscidians like we've been
talking about, get smaller when they are on an island because
they don't have to be as big and like scary to predators when
there aren't any big predators. So then you get the cute
channel. They can just be themselves.
They can. Be adorable.
I've always wanted to go to the Channel Islands off the coast of
California because they have pygmy mammoths, fossil pig
mammoths there because of, again, island dwarfism.
So we'll have to do maybe we can go there or go to we were just
in California, but we can go again.
It's still there, yeah. It hasn't disappeared.
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Even with the delay, I could hear you laughing the second I
said sexy. Diarrhea couldn't, couldn't.
Keep it together. It's so fucking stupid.