Imagine a world so warm that the ocean feels
like a hot tub. Huge volcanic eruptions have pumped the air
full of globe-warming carbon dioxide. And with the continents locked together from
pole-to-pole in the supercontinent of Pangea, the world is hot, flat, and very, very dry. Early reptiles and mammal ancestors thrive
in this sweltering land, dominating a landscape that’s still struggling to recover from
the Permian extinction. This is Earth, 250 million years ago, at the
beginning of the Triassic Period. But then, starting around 234 million years
ago, the climate suddenly changed, for the wetter. The rains finally came to this hot, dry world. And then they stayed … for two million years. This period of intense rain killed off many
of the early reptiles and … confused the heck out of the geologists who found the flood
deposits millions of years later. This time is known as the Carnian Pluvial
Episode, and it set the stage for a new group of animals to take over the world: the dinosaurs. Evidence of just how hot and dry the world
was at the start of the Triassic is trapped in the land beneath our feet. Rocks from that period are mostly swaths of
red sandstones and soil deposits from dry woodlands, with no sign of the coal swamps
that had covered the world during much of the Permian. And one major reason that the world was so
dry was the shape of Pangea. With all the continents locked together, rain
clouds couldn’t move much past the coastlines, and there were no big mountain ranges to break
up the low, arid land. Now, dinosaurs did exist in this dry, post-Permian
world. But they were still vying for their place
among early reptiles and reptile-like mammal ancestors. The dominant carnivores back then were the
early crurotarsans, a broad group of croc-like animals that included reptiles like pseudosuchians
and phytosaurs. For example, there was Ornithosuchus, which
had long hind legs and could actually stand up when it wanted to run, which I imagine
would’ve been both awesome and terrifying to actually see. But even stranger than these were the rhynchosaurs,
herbivores with parrot-like beaks and, sometimes, cheekbones to die for, all on a chubby lizard
body. And although there were no true mammals, there
were dicynodonts — the closest things to them at the time. They’re actually more closely related to
us than, say, Dimetrodon, despite being scaly, four-legged creatures with bills and tusks. All of these fascinating creatures were widespread
for most of the Triassic, with one species of dicynodont – called Lystrosaurus – being
so common all over the world that its fossils were actually used to help construct the idea
of Plate Tectonics But these animals, adapted as they were to
life in a dry climate, were in for a big shakeup. Most of what we know about the history of
the climate comes from plant fossils and rock types. And in the early 1990’s, two British geologists
found rocks that didn’t match the dry climate of the Triassic that they knew. Instead of finding red, slowly-deposited sand,
they found thick layers of river rocks, sediments from giant lakes, and evidence of coal swamps. All of these were signs of massive rainfall,
over the course of some two million years. But stranger still, these traces of a suddenly
wet climate turned out to be everywhere, from England to the Americas to Israel, in regions
that were far apart at the time. That meant the rise in rainfall must have
been world-wide. Initially, other geologists were skeptical. Couldn’t these rocks just be explained by
a lot of big local floods? Well, over the next two decades, reports of
more and more weird rocks kept trickling in, and they kept pointing to a world that was
getting wetter and wetter. The rocks revealed coal deposits in Austria,
traces of ancient lakes in Italy, wet soils in Utah, and giant rivers in China. And they all dated to the same window of time
— between 232 and 234 million years ago. In time, this phenomenon came to be known
as the Carnian Pluvial Episode, or CPE. The Carnian is the name of the geologic age
within the Triassic when this all happened. And for what it’s worth I seriously thought
about naming this episode the Chronicles of Carnia but I didn’t because that would
have been dumb. And “pluvial” means rain, and it rained
a whole awful lot. For example, one estimate suggests that the
average annual rainfall in what’s now Utah almost quadrupled, reaching a peak of 1400
millimeters, or about 55 inches of rain a year. For context, that’s how much that a temperate
rainforest gets today, like say, in the Pacific Northwest. And this would have happened over, and over,
and over again, all around the world. It was not one big flood; it was more like
floods every year, all over the place, for two million years. And with all this rain, things were bound
to change – and one of the biggest changes was the sudden abundance of dinosaurs. In rock dated to the start of the Carnian
Pluvial Episode, dinosaurs account for about 5% of the fossils of terrestrial vertebrates. But by the end, they make up more than 90%
of those fossils. So what made the dinosaurs so suddenly successful? Were they better off than their competitors
in this newly wet world? Or did other animals simply die, leaving them
to rule the world by default? The key might not have been the rain itself,
but what the rain brought with it: a proliferation of giant plants! During this time, we begin to see lots of
large conifers, and big coal-forming plants, like the primordial-looking Bennettitales. For herbivores, this change in food supply
could have been a game changer. For example, rhynchosaurs were abundant, but
they were also … short. And they couldn’t stand on their hind legs
to reach higher leaves. This would’ve been fine in a dry environment,
where plants tend to stay close to the ground. But in a wet forest, rhynchosaurs would’ve
only been able to eat smaller plants, or whatever leaves and fruit fell to the ground. Meanwhile, dicynodonts were herbivores, too,
but they didn’t have teeth. And, they also didn’t use gastroliths, the
rocks that some animals – like birds – swallow to help digest plant material. Without teeth or gastroliths, dicynodonts
would have had a hard time eating anything fibrous, like wood. And sure enough, fossils of dicynodont poop
from this time have been found to contain the digested remains of mostly soft ferns,
with only very small amounts of wood. By comparison, some plant-eating dinosaurs
– which had both teeth and gastroliths – left us poop fossils that are up to 85% wood! Which is a lot of fiber. So as the climate became wetter, soft small
ferns were quickly replaced by tall woody conifers, which the dicynodonts and rhynchosaurs
didn’t eat. And without the rhynchosaurs and dicynodonts,
then the carnivores — those crurotarsans — would’ve lost a lot of their food supply. So maybe, instead of being better-adapted
to this new environment, dinosaurs were just the only major group of reptiles left standing. Or, y’know, squatting. Even though we don’t know exactly why the
rain helped the dinosaurs, we do know that dinosaurs became a lot more abundant during
the Carnian Pluvial Episode. And the dicynodonts, the rhynchosaurs and
many of the early crurotarsans soon went extinct. Now, there’s still the question of: What
made it rain for two million years in the first place? Well, right before the rains came, some 235
million years ago, a huge burst of volcanic activity took place in Alaska and British
Columbia. Today it’s known as the Wrangellian eruptions. These eruptions lasted for more than 5 million
years, churning out a layer of lava that got to be 6 kilometers thick, and releasing enough
CO2 to raise temperatures by about 3 to 10 degrees Celsius worldwide. And, over a very long time, warmer temperatures
can create a wetter climate, because they can speed up the water cycle, driving more
evaporation of surface water into the atmosphere, among other things. And in fact, because of this increase in atmospheric
moisture, the CPE is also sometimes called the Carnian Humid Episode. But for what it’s worth, my favorite name
for this episode by far is The Wet Intermezzo. Which I think is delightful so let’s try to bring that term back, OK? Anyway, after about a million years of volcanic
activity, the atmosphere became so warm and wet that rain could finally reach even Pangea’s
vast interior. OK but then, how did it stop? Well, when carbon levels are really high for
a really long time, our planet can be pretty good at getting some of the extra carbon back
into the ground where it belongs. Plants take it in and store it in their tissues;
weathering and eroding rocks absorb it; and the oceans soak it up to form carbonate rocks
like limestone. So as the Wrangellian eruptions slowed down,
the carbon cycle was eventually able to stabilize, excess CO2 was reabsorbed from the atmosphere,
and the CPE gradually came to an end. By the time the eruptions had completely ended
230 million years ago, the world had returned to a classically hot, dry Triassic climate
that only ended when Pangea began to break up. But even though the Carnian Pluvial Episode
was short – only 2 million years – its impacts on life were permanent. All that rainfall helped conifers spread and
diversify, leading to the pine trees we know today. And while the start of the Triassic may have
been the land of weird, croc-like-things running on their hind legs
by the time the rains had ended, the world had fully entered the age of dinosaurs. Thanks for joining me for this wet intermezzo! Now, wouldn’t you like to have all of natural
history right there on your wall? I would and now you can! With the first-ever Eons poster, created by
Franz Anthony. Just go to DFTBA.com and links are in the description Now, let me know what you want to learn about,
because you know by now that we read your comments! And if you haven’t already and I don’t know why you wouldn’t have — but if you havent, you should go to youtube.com/eons
and subscribe. Thank you.

Author Since: Mar 11, 2019

  1. Imagine a desert like place getting rainy weather like London for 2 million years and what effects that would have had.

  2. So wait, did it constantly rain? Meaning both during the day and night all of the time
    Or was it consistently raining? Meaning it didn't rain all the time, but did so very often

  3. What if when humans go extinct. Another similar species found our old graveyards and finding our remains was like us finding dinosaur fossils

  4. "This time is known as the Carnian Pluvial Episode"
    or, if you're British
    "Summer"

  5. The title of this video is obviously a clickbait…CPE simply means increased rainfall and floods all over the globe for the period of 2 million years 3:43

  6. Looks like they mixed humans with animals so that people can called it evolution. This is what they did. Those look like hippos but they gave them beaks or beaver teeth.

  7. Currently excavating a large ridge of dirt beside a river. I have found a 3 foot thick layer of river rock covered by 10-12 feet of red clay. With a gray sandy compacted dirt underneath. It seems to run the entire length of the ridge. It is located around 150 feet from the actual river and is easily a hight of 30 feet from the current water level. I wonder if this may have been how it was put there. I had originally thought it could be deposited from glaciers. But now I'm not sure. The location is in the blue Ridge mountains of n.c.

  8. Now i dont feel so quilty about Dinos, i feld sorry for them to make plece for us, but yhey started the same way? Stopped frocks

  9. Did you also know that the Vatican is just one big Snake, with cobble stone's to represent the scales ? Research that which is real instead of guessing about what was and what was not real in the past.

  10. For anybody who lives on rain-catchment like me, we love rainy days!

    So then…

    This isn't that much rain?

    51.53 inches

    Hawaii Takes A New Spot In U.S. Rainfall Records, After Hurricane Lane Drenches State On the Big Island, Mountain View recorded 51.53 inches of rain from Wednesday to Sunday — Aug 27, 2018

  11. Only 2 millions years… You do realize that this is twice the length of time that man has roamed the planet. On an evolutionary scale man is relatively new to the planet. People worry about what man is doing to the planet… The planet has been through worse than anything man could do to it. It can and will recover long after man is gone from it's surface.

  12. Can NOT get used to Erbs & Erbivores. I note, with interest, – you don't have einous crimes, OR put oney on your toast. :¬)

  13. Your videos are much wider than tall. The figures of the presenters take up about 1/3 of the image. Yet, the presenters keep their elbows stuck to their ribs and all their hand gestures are in front of their bodies as if they were being recorded in a square format. This seems stiff, constricted, and contrived. Why not the occasional broad gesture? Why not relax the arms a bit?

  14. Dinosaurs became huge because of the amount of oxygen that was on earth during their time. I would not be suprised if the 2 millions years of rainfall had something to do it

  15. Aha!!!?2million years¿?????but weather bureau says forty days and forty nights ONLY!!!!!!??????Check weather report genesis 7:11-12

  16. This is ruh- tahded, in order for animals, trees and other biology to fossilize or Permineralize, it has to be covered quickly. You can find fossils at the top of mt. Everest and whale fossils in the dessert, what you say isn’t backed by evidence

  17. A global low pressure system that must have been caused by some evil corporation of the future who invented a wormhole funneling pollution into the past as a way to avoid paying carbon tax……..DAMN SOB'S….IM SO MAD ABOUT IT

  18. How much climate change is due to climate cycles and planet movements? How much is due to human necessity? How much is due to human greed?

  19. the climate changed….i dont believe it , how could the climate change without people eating meat and cars emitting hydro carbons… you guys are making it up…the climate couldn't change

Related Post