When the Rainforests Collapsed - Lake Harding Association

When the Rainforests Collapsed

When the Rainforests Collapsed

By Micah Moen 100 Comments February 25, 2020


Way back, about 310 million years ago, a lizard-like
creature took shelter in a hollow stump in what’s now Nova Scotia. It was small, not much bigger than your hand,
and it hunted for insects in an ecosystem that was way different from anything you’ll
find in Canada today. It lived in a warm, swampy forest, full of
giant ferns and tree-like plants that reproduced using spores, not seeds. But this lush environment ultimately caused
the death of that little creature; its fossil remains were found preserved in that stump,
buried by sediment from a river that overflowed its banks. We call that little creature Hylonomus, and
it’s the world’s earliest known reptile. Now, this also makes it one of the earliest
amniotes, animals whose eggs contain a special membrane, called an amnion, that allows them
to survive on dry land. Today, amniotes include all reptiles, birds,
and mammals. And Hylonomus was not alone. It shared its tropical forests and humid swamps
with amphibians like Cochleosaurus, a giant, semiaquatic ambush predator – like, the amphibian
version of today’s crocodiles. But then, about 305 million years ago, something
happened. The climate had been shifting for several
million years, from steamy and tropical to drier and more seasonal. And that shift took a toll on the swamps and
rainforests, which slowly began to disappear. By around 299 million years ago, most of those
humid forests were gone. And along with them disappeared a host of
early amphibians, like Cochleosaurus, that couldn’t cope with the newly dry conditions. This extinction event is sometimes called
the Carboniferous Rainforest Collapse, and it set the stage for a takeover that would
be a crucial turning point in the history of terrestrial animal life. Because, the collapse of the rainforests was
followed by the spread of cooler, drier landscapes that were less hospitable to the big, dominant
amphibians. And yet, one group of tetrapods was poised
to take advantage of that new terrain: the first amniotes — animals that, like Hylonomus,
could lay their eggs on land. And these creatures would turn out to be our
very early ancestors. So, the disappearance of the rainforests was
just as much an environmental catastrophe then as it would be today. But if it weren’t for that time when the
rainforests collapsed – in an extinction event that you probably haven’t heard of – our
ancestors might never have made it out of the swamps. The Carboniferous Rainforest Collapse is named
after that window of geologic time when it took place: the Carboniferous Period. Carboniferous literally means “coal-bearing.” And we call it that because, over millions
of years, all of that vegetation in those dense, humid forests turned into peat, and
then coal. The Carboniferous was given its name in 1822
by two dapper English geologists. But it’s only been within the last 20 years
or so that researchers have started to take a closer look at what happened at its end. So we’re still piecing together the story
of the Rainforest Collapse. But it looks like changes in climate played
a big part. We can see evidence of this in places that
are rich in coal today, like the Appalachian and Illinois Basins of North America. Because, coal is actually full of the spores
that those ancient plants used to reproduce. So scientists can study those spores in the
coal to figure out what kinds of plants lived in a certain place at a certain time. And, tracking changes in the types of spores
over time reveals that the fossil record of plants seems to shift back and forth between
wetter and drier-adapted species throughout the latter half of the Carboniferous, between
about 323 million and 299 million years ago. And the coal beds themselves start to become
thinner and thinner, which further suggests that the climate was getting drier. Shorter cycles of hot wetlands meant there
was less swamp vegetation to decay into peat and then coal. Now, some experts think that a short but intense
glacial phase caused the collapse, based on records of sea level change and changes in
the types of fossil soils we see at the time. Plus, a third factor was also at work: large-scale
volcanism. One group of paleontologists has suggested
that the eruption of two big areas of volcanic activity – one in what’s now northwest Europe
and one in Mongolia – may be linked to the rainforest collapse. Regardless of what climate changes exactly
caused the rainforest collapse, its effects were significant for both plants and animals. But it’s clear from the fossil record that
this was an especially tough time to be a plant. Because, as the rainforests dwindled, they
also went through lots of changes. The dominant trees of the Carboniferous were
the lycopsids, also known as scale-trees, tall, tree-like plants that actually aren’t
closely related to modern trees. And as the collapse began, they died off pretty
quickly and abruptly. A few lycopsids are still around today, like
the clubmosses, but their heyday is long over. Then, the lycopsids were mostly replaced by
another kind of wetland plant, the tree-ferns – which are also not trees. They’re just ferns that grow trunks, like
trees do, and they’re still around today. This switch from lycopsid forests to tree-fern
forests is important, because they’re different kinds of habitats. Lycopsid forests had more open canopies, letting
the sun shine in on the flooded forest floor, while tree-fern forests were darker, with
more closed canopies. And, speaking as someone who moved from New
Mexico to Montana in the winter, I can tell you that most organisms don’t cope well
with abrupt changes in their habitats. Anyway, after undergoing changes like these
for millions of years, by around 300 million years ago, the equatorial coal forests were
definitely on their way out. This is one of only two mass extinctions of
plants known from the fossil record. And we also know that around nine families
of amphibians and amphibian-like tetrapods went extinct during this time, like the baphetids,
which were big, fish-eating aquatic predators. What happened next depends on who you ask. But either way, the results turn out to be
the same: the rise of the amniotes. One group of experts has suggested that the
collapse left behind isolated patches of rainforest where separate populations of tetrapods — including
amniotes — diversified into new species. The scientists tested this by studying differences
in tetrapod diversity from the early Carboniferous all the way through the middle of the following
period, the Permian. What they found was that, worldwide, tetrapods
remained diverse, but their communities shrank; so, there were more different kinds of tetrapods,
but fewer of them. According to this model, the collapse caused
the extinction of a lot of the dominant amphibian groups. But it also created new opportunities in those
patches of rainforest for the amniotes to diversify and thrive. And it was those early amniotes that moved
into new dietary niches, becoming carnivores and also the first large herbivores, like
the sail-backed Edaphosaurus. Now, a second hypothesis argues that the collapse
of the rainforest actually made communities of tetrapods more connected with each other,
which ended up helping amniotes in a different way. This model focuses on how closely-related
different tetrapod species were, in relation to where they lived. And it finds that species that were far-apart
were still more closely related than expected, suggesting that there must’ve been movement
between communities. So, instead of tetrapods being trapped in
patches of rainforest surrounded by newly dry land, there might’ve been a more gradual
transition from wet to dry. And this would’ve created larger, more connected
habitats that the amniotes could’ve taken advantage of, equipped with new features that
allowed them to live completely terrestrial lives. Either way, both hypotheses agree that the
diversification of the amniotes was a major outcome of the collapse. Because, the amphibians that dominated the
Carboniferous were tied to the swampy environments of the coal forests, but the amniotes weren’t. And this is probably because of two unique
traits that set the amniotes apart from the amphibians. They didn’t have to lay their eggs in water;
they could do it on dry land. And they had scales that helped them retain
moisture in more variable climates. These adaptations made it possible for them
to expand into all that new, dry habitat, and evolve into the weird forms we see in
the Permian Period. These were things like the sail-backed Dimetrodon
and the barrel-bodied, tiny-headed herbivore Cotylorhynchus. And they included the amniotes that would
eventually give rise to us, some 300 million years later. Like, I haven’t met you, but I can tell
you that, even though you don’t lay eggs, you my friend are an amniote. If not for the collapse of the rainforests
where little Hylonomus once lived, way back in the Carboniferous, amniotes might not have
had the chance to take over from the giant amphibians. It was an ecological catastrophe in its time,
but this little known extinction event shaped the world we know today — including by making
us possible. Thanks for watching PBS Eons, which is produced
by Complexly. If you’d want to keep imagining the world
complexly with us, check out Animal Wonders hosted by Jessi Knudsen Castañeda. Animal Wonders is an animal rescue and education
facility that cares for close to 100 exotic animals and non-releasable wildlife. Every week on the Animal Wonders YouTube channel,
Jessi features different animals and shares what it’s like to keep them happy and healthy. Recently, Jessi and the Animal Wonders team
took in Tigli the arctic fox. If you’d like to learn all about Tigli’s
story and find out how he’s getting along with the other foxes at Animal Wonders, there
is a link in the description to a video all about that. Big scaly high fives to this month’s Eontologists:
Patrick Seifert, Jake Hart, Jon Davison Ng, Sean Dennis, Hollis, and Steve! Become an Eonite at patreon.com/eons and help
us keep sharing stories from the ancient past! And thank you for joining me in the Konstantin
Haase Studio. Go to youtube.com/eons and subscribe!

100 Comments found

User

Tricky

What is the current extinction event called?

Reply
User

ChopRamen

would love a video about the species today that have been around the longest and what has allowed them to survive until now

Reply
User

persivefire

Is it just me or does this collapse feel familiar?

Reply
User

Aaron Burmeister

Hmmm, it’s almost like climate change has always happened over and over throughout the history of our planet. Makes one think…

Reply
User

stefanos tokatlidis

And this is how the best geological era of our planet ended.

Reply
User

Pleunie Van Den Hurck

I would like to know more about animals around the ice age

Reply
User

Joppe

Thank you for pronouncing "niches" correctly

Reply
User

Carrier Taiyo

Hate to break it to you but I'm not an amniyote

Reply
User

Jamal

nervously hides eggs haha yeah man definitely an amniote

Reply
User

Troy Young

All the titles seem to me like the scientists are saying it’s okay to ruin the earth because it’s happened before and it recovered

Reply
User

Chuck Balyeat

All that co2 led to runaway global warming , they auto ignited, and then things and stuff happened

Reply
User

David Presley

Do reptiles who give live birth still fall into the amnion category? I tried looking it up and couldn't find an accredited source so it's time to ask the youtube comment section.

Reply
User

Pyro1456

This is surprisingly relevant given the current situation with our own rainforests

Reply
User

tehbonehead

0:35
Use an egg.
I was already doing that.
1:33
No. A stronger egg.
Put water in it.
Baby is in the egg.
In the water.
In the egg.
Works for me.

Reply
User

Klaede

I just realized something, since billions of years ago the climate has been changing all the time and it's still changing even now. So all that talk about trying to stop climate change, isn't that actually going against nature?

Reply
User

Victor Collazo

Is it true that the only place where these forest still exist are in an Aurelian trench?

Reply
User

sky kawaii tomboy

Ckoroko

Reply
User

Hisame Artwork

thank you for another great vid <3

Reply
User

Alec Smith

Great video. Please do one on the domestication of dogs.

Reply
User

Ciaran Grace

does anyone actually know the agreed-upon pronunciation for cotylorhyncus? because that was not what I was expecting. Great video once again!

Reply
User

D.J.L Hayes

Imagine all the coal we burned, all the information we burned. It's like burning the alexandrian library for plants

Reply
User

Cush

"When the Rainforests Collapsed
16 hours ago"

Sounds about right…

Reply
User

John Newman

Request: The Evolution of Fur.
Every stem-mammal model I see looks looks quite hairless, and the mammals in the age of Dinosaurs look like furry mice. How do we transition from Dimetridon cousins to Rodent-like early mammals?

Reply
User

Foxy-CAM TV

Everybody is moving to montana.Read between the lines of what this video is trying to teach.

Reply
User

The American Viking

So what you are telling me is that the climate has been changing for millions of years and it is in fact not because of humans…. huh, who would have thought.

Reply
User

jesse gros-louis

Make an episode about how crabs evolved four different times. Like "crabs appeared," and then"more carbs appeared," "Iwasn'tdoneyetmorecrabsnow!" and then finally SLAM "You got more crabs" Like, earth went through some serious college phase.

Reply
User

Kim Harder Fog

What, something of note happened around Denmark. That is usually not the case when looking into the ancient past.

Reply
User

themarquess

This feels like a prelude to the episode about placentas we've been promised a while back.

Reply
User

timomonochrom

7:02 how i see myself in november when i wear my winter jacket for the first time

Reply
User

Robert Stuart

Animal Wonders Montana is a good channel.

Reply
User

SweetMisery

I’m still waiting on that placenta evolution video

Reply
User

Aishwariya Sweety

7:26 and we are killing the world. So it sort of cancels itself out.

Reply
User

Ojama Black

Well, they can’t blame humans for this climate change.

Reply
User

Mr Moncherz

How did the dinosaurs try and stop climate change like we humans do?

Reply
User

Kelly Ann

Canada sucks.

Reply
User

Noah Body

I actually would like to see a video about the Brontosaurus and how it was finally set apart from the Apatosaurus.

Reply
User

Cody Burkett

Carboniferous Rainforest Collapse sounds like a Postrock album title. Same with Messinian Salinity Crisis… now all you need is Slide Mountain Ocean.

Reply
User

but-can-you-fly

Bold of you to assume I don’t lay eggs 👀

Reply
User

Steven Baumann

Illinois is often called the Middle East of coal. Trouble is, most of it contains a lot of sulfur.

Reply
User

¡Carajo!

For some reason the audio was impossible to understand. Like 2x the speed?

Reply
User

iTheLizardWizard

Steve is a goat

Reply
User

Gabriel Constanza

Carboniferous? I think you mean Mississippian and Pennsylvanian.

Reply
User

Bitten Hare

Yes like the current rainforest collapse, except ours is happening over decades not millions of years!

Reply
User

Poof a

"When the rain forests collapsed."
Yeah, that was only a couple months ago.

Reply
User

planescaped

Just signed up to you guys on patreon. I was simultaneously shocked by how much money Scishow rakes in and how little you guys are. Explains why Scishow has near daily uploads and two side channels.

Support Eons peoples! I want daily archeology/anthropology vidyas!

Reply
User

granskare

We had coal in Illinois & after it appeared to be used up, then to Indiana, Ohio, then West Virginia where people seem to not want to adapt, Just my opinion.

Reply
User

Thorkil Værge

The Carboniferous period is named after the two British geologists, Carbon and Iferous.

Reply
User

finthefishsep20toma

Did anyone else notice how "Steve" stopped being a patreon after everyone in the comments started talking about him a few episodes ago? Makes me sad, he must have felt uncomfortable from all the attention or something 🙁

Reply
User

John Ortmann

"Tree" is not a taxonomic clade. It's more of description: woody and more than 15 feet tall. So, yes, tree ferns are trees. Just once try getting through one of these without sticking both feet in your mouth.

Reply
User

DragonofEpics

I thought “Oh they’re doing an episode about modern times. Huh.”

Reply
User

Rory Bingham

anomalocaris… please!!!

Reply
User

Jack Black

Great videos.

Reply
User

Corey Taylor

"from new mexico to montana in the winter"
big oof

Reply
User

Noble LeGrand

A beaver killed that lizard

Reply
User

nariu 7times

The writing is always so good, thank you!

Reply
User

E 10

0:26.. trees dont last that long..

You talking about..
310 million years ago

Reply
User

Dano Armstrong

I'm pretty sure the climate change that caused the collapse of those rain forest was due to time traveling humans going back to that period, and using fossil fuels.

Reply
User

Rob Babcock

Hahaha! I also moved to Bozeman in the winter. What can I say- it seemed like a good idea at the time! 😉

Reply
User

Gabriel Montufar

Now I understand the amniotic fluid for babies

Reply
User

lifesentence

Climate change eh.

Reply
User

Shaun Whitehead

All they needed was a climate change revolution = high taxes on all reptilians

Reply
User

Daniel Maldonado Sánchez

Hey Eons! Can you please make a video on the evolution of triceratops head?

Reply
User

Thomas Long

From the title I thought it was referring to today.

Reply
User

miseryschewtoy

I like his necklace. What a great host!

Reply
User

Chad Coley

After each mass extinction a new Eden came afterwards.

Reply
User

CaptianSkinder

Did that lizard-like creature tell you all this?

Reply
User

Alexey Souvorkin

What do you mean we don't lay eggs?
Did you miss the class on menstruation?

Reply
User

Ben Depeel

So the rain forests dissapeared due to climate change and life went on it was actually essential for evolution huh!!

Reply
User

BadHombre

Way to gloss over the fact that it was COOLING planet that caused the collapse.

Reply
User

Ghostcamel

Hey @PBSEons what do you think about this theory: Did Humans Domesticate Themselves?
https://www.sciencedaily.com/releases/2018/02/180215110041.htm
Seems very plausible to me.
And also, do you think we could teach cats 'civilization', much like we taught ourselves 'civilization', not domestication.

Reply
User

Pyro Raptor

Interesting

Reply
User

Adam Reilly

I am an Amniote……..cool 😁

Reply
User

Alan Choi Chang

did u guys fire hank? its been a while since ive seen him…

Reply
User

Justin Pigott

Good morning 🌞 PBS Eons I wanted to thank Blake for doing an amazing job on why Rainforest's collapsed. I thoroughly enjoyed watching him explain what happened. It's always a pleasure to watch him with his charisma, enthusiastic, personality on the topics he decides to cover. 😁 My question to you is will your show do a episode on the European Cave 🐻 and the Prehistoric Polar 🐻?

Reply
User

Mr Marxmin

When you said "I haven't met you but I know you're an amniote" my bearded dragon started bobbing his head

Reply
User

RoThotic

i would die for arthropleura can i get a video of u just talking abt them theyre so cute, u can also talk abt other giant prehistoric bugs cuz nobody talks abt that time enough. its like everyone wants to forget we had giant bugs

Reply
User

Daniel Buckler

Humans have been causing climate change for eons smh

Reply
User

Matias Wanntorp

The tree ferns that were around during the carboniferous are not the same tree ferns that exist today. They actually belong to two different groups of ferns, Marratiopsida and Polypodiopsida. (Ray F. Evert, Susan E. Eichhorn(2013), Raven Biology of Plants, New York, NY: W. H Freeman and Company)

Reply
User

TEACHurNOOB

Can you do an episode on the evolution of grasses?

Reply
User

Dustin Freeman

The Carboniferous was a weird period in Prehistoric times. It was all forests, swamps and marshes. I never guessed that amphibians and reptiles shared the same forests before it collapsed.

Reply
User

gasparinha

Animal Wonders is great! It's a nice thing for younger kids as well.

Reply
User

Silent Hunger

the 92 thumbs down on this video are obvious evolution deniers

Reply
User

Thirst Fast

2:55 Uhhhhggggghhh yeah, there is a lot of information preserved in all those fossil fuels we just burn or otherwise process…. I understand cycles, we're just a weird flood.

Reply
User

peter

100 million years from now: "And if it wasnt for that extinction event that hardly anyone has heard of…" ~ a 7 foot bipedal cockroach to a classroom full of cockroachlings.

Reply
User

South Ka Chandan

I wonder how can scientists be so sure about events that happened millions of years ago?

Reply
User

TheTobyJosh

Perhaps you could handle the ‘not a woody angiosperm’ issue differently. I hear many people talk about how a given species isn’t technically a tree, when in fact there is no clear definition of “tree” beyond ‘a perennial plant with a tall stem or trunk, usually having branches and leaves.’ Palm trees are monocots, and they are also trees. Tree ferns are polypodiopsids and trees. Oaks are sometimes vines. If its tall like a tree, perennial, and its a plant, well shiver me birches you got a tree.

Reply
User

Herbert Miller

And we're about to see it happen again

Reply
User

misirloupowerslide

I know this is some jurassic park bullcrap but wouldn’t it be clutch if we could revive an old spore based plant from the spores found in some coal !!

Reply
User

kennarama

Ahhhh Blake is my fave. I like them both but his voice is my fave

Reply
User

Thomas Munns

I really love long history, but you say quickly and abruptly like it's not hundreds or thousands or hundreds of thousands of years.. and we're supposed to believe civilization has only ever excited maybe 10,000 years.. yeah right fossils are rare.. you won't find evidence of a modern house one million years from now.

Reply
User

Renat Galeev

A video about moths or butterflies common ancestors. O about how metamorphosis evolved! PLEASE

Reply
User

Константин Иванов

Yo, I REALLY appreciate the effort to talk slower. It actually makes this way more enjoyable and easy to absorb. Keep it up, you guys are awesome !

Reply
User

andrew batist

please do an episode about Saurophaganax Maximus " when Allosaurus got huge " or Deinopithecus the giant Baboon

Reply
User

Kyle Shepherd

Lol not to make fun but 7:42 “Animal Wonders is an Animal Wescue” made me laugh! They’re such a great organization but I had to point it out 🙂

Reply
User

B0lzenlol

Did we already had an episode on "How viviparity became a thing" ?

Reply
User

Wade Spencer

"I haven't met you, but I can tell you that you my friend are an amniote"

offended frog noises

Reply
User

Alejandro

So… my worst fears and nightmares are inevitable… the Ants will betray us and demand to live as individuals!!

Reply
User

Keitrah Gatto

Did snakes have arms?

Reply
User

Ernie Llerena

I like this dude. He doesn't rush when he speaks.

Reply
User

Thomas Jarrett

Could you do a video about the evolution of Venom?

Reply

Add Comment

Your email address will not be published. Required fields are marked *