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0:00
Hello, how you doing? Have you stopped to smell the roses recently? You probably should. Roses are cool, and as you will see today, flowers in general are so cool because we have finally arrived at the Cretaceous Period, which lasted from 145 to 66 million years ago. This is the final phase of the Mesozoic Era, also known as the Age of the Flowers, but more iconically, the Age of the Dinosaurs. The dinosaurs popped off, but as I've said throughout this entire era,
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the world was much more than that—more than dinosaurs. There were ammonites and turtles the size of cars, the plants were in their peak era, the fish were heinous, and the reptiles were evolving at high speed. And, to put the cherry on top, this would all come to an end in the most dramatic way possible. So without further ado, my name is Lindsay Nikole, and this is the History of Life on Earth that
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we know of. Let's get the global conditions out of the way. Last time, in the Jurassic, Pangaea was breaking apart: Laurasia in the north, Gondwana in the south. Now, these started to break apart, and by the time the Cretaceous ended, we had the current continents that we know and love today. There was this song in fifth grade—the seven continent song—and I tried to look for it for this video but I couldn't find it. There were all different
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seven continent songs, but the one I'm familiar with was like, "Seven continents in the world, seven continents," and it was very, like, salsa, you know? But I couldn't find it. So, just like the Jurassic, the Cretaceous was still generally warm and humid, with little to no ice at the poles. But the poles were still interesting, as you will see in a bit. Stay tuned for that. When you imagine the landscape of the Cretaceous, especially with help from shows like
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Prehistoric Planet and Walking with Dinosaurs, or my personal favorite, The Land Before Time, you probably think of it as very similar to today—maybe a bit more lush and tropical, but with all the same characteristics that we have now: rivers, mountains, beaches, deserts, maybe more than a few plateaus, trees, soil, classic shit. But there's one thing missing from our classic landscape today that didn’t appear until the Cretaceous,
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that we know of. It’s so basic, I wouldn’t be surprised if you can’t even guess it, because it’s just so taken for granted. I'll give you a hint—it’s a plant. I’ll give you a second to think about it. Grass, dude! Grass didn’t exist until now! When I first learned about this a few years ago, I was shocked and decided I needed to learn everything there is to know about grass. Turns out I knew absolutely nothing about grass.
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So let me give you a rundown. Grass is a type of angiosperm—flowering plant, go figure—which is why it hadn’t shown up until now. And what makes grass grass is the way that it grows. Most plants grow from the tips; grass grows from the base, making it a lot easier to regrow after being mowed by your suburban father or perhaps grazed on by an herbivorous dinosaur, a group of animals that drastically increased in size and abundance throughout the Mesozoic.
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Quite a solid adaptation for survivability if you ask me—round of applause for the plants. The oldest grass fossils date to somewhere around 100 million years ago, and up until recently, it was thought to be half that. It was thought that the Age of Dinosaurs didn’t see grass at all, but scientists have recently found little microscopic structures of grass, called phytoliths, in the teeth of a hadrosaur and in coprolites—or fossilized shit—of titanosaurs.
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"That is one big pile of shit." This was likely a pretty small innovation in the Cretaceous, but eventually, this lineage would explode. Today, 20 to 40% of the land on Earth is covered in grass. Humans love grass. Wheat is grass. Rice, barley, corn, other grains—bamboo! Grass is so cool, and not the average lawn or golf course grass—that grass is objectively not cool—but other grass, hell yeah. Make sure you go touch some today.
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I mentioned that grass is a type of flowering plant, or angiosperm, which you might remember I first talked about last time, in the Jurassic. For a long time, it was thought they first appeared sometime in the Cretaceous, but newer fossil evidence is pointing to origins in the Jurassic, and there’s some molecular evidence that points to some time even earlier than that. So the origin of flowering plants is on some shaky ground at this moment in time. But at this point,
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it doesn’t really matter because what we know for sure is that they were popping the fuck off in the Cretaceous, exhibit A being grass. This was the time of the angiosperm explosion. The flowers were taking over, and other plant lineages, like conifers, were getting wrecked. I would imagine they would have felt bitter if they had thoughts and feelings on an evolutionary scale. It’s like
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the new girl in school showed up, and she was hot, like way hotter than the cycads and the conifers. She was evolving brightly colored flowers and fruit, traits that made her extremely popular right away within the pollinator community. Insects loved shit that’s tasty and easy to see. From a numbers point of view, angiosperms went from representing 0 to 5% of fossil plant life in the early Cretaceous to over 80% in the late Cretaceous, which is fucking insane. And of
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course, this takeover has been given an official name—the Angiosperm Terrestrial Revolution. Not very catchy if you ask me. I think a better name would be “Flower Power Time,” but that’s just me. Think of all the flowers you’ve ever seen in your entire life. It’s probably not even close to all the different flowers that actually exist today. I bet if you were to go into a remote rainforest right now, you’d see flowers that make you feel like you’re on a different planet. Actually,
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if you like to dabble in your own Flower Power Time or are just bored, look up “weirdest flowers” on Google. Flowers are nuts. And those are just what exist today. I can’t even begin to imagine what some flowers must have looked like during the Cretaceous that we’ll just never know about due to the oppressive nature of the fossil record. I’m starting to get off track. The flowers are just a small aspect of the development of angiosperms. Ultimately,
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they have taken over the world. Angiosperms make up 95% of all land plants today, and this explosion seems to have been kickstarted during the Cretaceous. But why? Actually, I guess I already answered that question—it was the insects. I mentioned last time that pollination became a bit more popular in the plant community during the Jurassic, and that became the start of a massive snowball effect. Insects started off by pollinating gymnosperms,
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like cycads—the basic, original pollen providers. Then, they started to make the switch to angiosperms, which were easier to see and also very tasty, like I said. This pushed flowering plants to become even more easy to see, even more brightly colored, offering even tastier pollen, and they diversified to shit. Becoming the Met Gala of their Cretaceous and exploding in success for their newfound partners. And insects did too—some became
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more specialized pollinators, focusing on what they found to be the most appealing flowers. Other factors affected their diversification, of course, like global temperature, other plants entirely, but insects and flowering plants were just bouncing off each other like nobody’s business. And the regular gymnosperms got left in the dust. Not completely, but angiosperms were the new toy, and gymnosperms were the ones that got stuck in the back of the
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closet. They were simply the victims of a free-market economy. So insects affected angiosperms, angiosperms affected insects, and so the Cretaceous saw the first appearance of probably the most iconic angiosperm pollinator of all time—the bees. You might remember I mentioned a couple of episodes ago that bees and ants would eventually evolve from wasps. It’s just the worst word on the planet—wasps. And not just any wasps—parasitoid wasps. Remember,
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the whole thing about parasitoid wasps is that the larvae eat the prey alive as part of their life cycle. They’re just horrific. And on a spectrum—a horror spectrum—some wasps will inject their eggs right into their prey. Others will paralyze the prey, bring it back to their nest to feed their young, and it seems as though bees evolved from this kind. At some point, a wasp must have tried feeding its young pollen instead of a paralyzed insect. Very nutritious
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and cruelty-free, pollen turned out to be a successful food source, and this eventually led to the lineage of bees. And thank God for that. The last thing we needed was more parasitoid wasps. Scientists estimate there are millions of them—not individuals, but species—millions of species of parasitoid wasps. Bad. That’s bad. So anyway, bees evolved, and bee colonies first appeared in the Cretaceous as well. Another colony animal that seems to have appeared in the
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Cretaceous is the ant, also from parasitoid wasps. They were present but not abundant, and wouldn’t be until after the asteroid impact that we know of. So, we will revisit them then. Another group that appeared: butterflies—from, you guessed it, moths. Shit was just getting more modern, but I was able to find one strange specimen that I think you will like. Let’s see if I can pronounce this: it’s called Hallucino-diogenes. Diogenessi? Dienni? Hallucinochrysa diogenesi, just keep
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it there. It’s a trash-carrying larval lacewing. What the fuck does that mean? Let’s start with the lacewing, insects that still exist today, named such for their wings that look like lace. I think their wings look sick. They look like those skeletons they have at Michaels or Spirit Halloween. The spider one is the worst. Dude, of all the horrific creations mankind has played a part in, this is the most foul. But anyway, this is a lacewing. Pretty cool.
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Larvae equals baby—we all know that by now. And trash-carrying is exactly what it sounds like: they carry trash. To insects, trash is anything—sand, discarded plant material, exoskeletons of their prey. They use this trash to camouflage since their entire world is littered with these materials. They also use it as a shield, i.e., defense. And on occasion, they eat the trash, a little bit. The Hallucinochrysa diogenesi was perfectly built to carry a thick amount of trash. They had
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extremely long, velcro-like appendages to tangle the trash into. The specific fossil specimen, found in 2016 in amber, had all sorts of trash wrapped up in it. Not only are they cool looking, and carry trash, but this is also some of the earliest evidence of trash-carrying behavior in the fossil record—so, educational as well. This fossil has everything. Imagine if we carried that much trash all day. Our backs would be completely destroyed,
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Now, back to the Cretaceous. Alright, before we move on to the ocean, I have a little land section that I don’t usually do because I don’t usually come across stuff for it. But this time I did—with fungus. I have two updates to share with you about fungus. The first one is pretty heinous, or sick, depending on how you look at it. So, let me know what you think. The Cretaceous fossil record holds the earliest evidence of a carnivorous fungus—yes,
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like, it uses animals as a source of nutrition. Probably something you don’t think about very often, or maybe at all. We typically think of fungi as decomposers, not as preying on living animals. It’s a little bit uncomfortable. The earliest evidence of this lifestyle comes from the Cretaceous. Scientists found it in amber that dates to about 100 million years ago, and it shows a fungus with specific fungus-trapping devices trapping nematodes. These specific trapping
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devices are called hyphal rings—they’re like sticky rings, and nematodes get stuck in them. Carnivorous fungi are thought to have evolved much earlier than this—because why wouldn’t they? Molecular evidence points to over 400 million years ago, which is not surprising at all. But the second fungus thing to tell you about is a little surprising, in my opinion. The Cretaceous also holds the earliest evidence of a mushroom: Gondwanagaricites
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magnificus, the oldest mushroom that we know of. You can kind of think of mushrooms as the fruit or flowers of certain fungi—the reproductive parts. "Love dicks." Seems like something that would have appeared much earlier in the fossil record, probably just hasn’t yet. But I digress. This mushroom was very small, about 2 inches long. I guess, what else would you expect from a mushroom? An analysis using electron microscopy found that
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it had gills under its cap rather than pores or teeth that many other mushrooms have. And I just found out what all those things mean in terms of mushrooms, so I’m going to tell you now too. Gill mushrooms are probably what you’re imagining—the ones that have those little thin paper sheets under their cap. A good example would be oyster mushrooms—one of the best mushrooms, in my opinion. I never had mushrooms growing up because my mom and my grandma are allergic,
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so I never had them. But then I tried them, and I like them a lot. I take King oyster mushrooms (Trader Joe’s has them), and I rip them into little, like, French fries. Then I throw them in some oil, put salt, pepper, a little bit of garlic, some butter, and I just cook them until they’re really crispy. They’re just the best. They’re so good. "Fucking delicious." I highly recommend them, if you’re not allergic. So, that’s gill mushrooms. There’s also pore mushrooms,
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with—you guessed it—pores under the cap. A good example would be the reishi mushroom. And the tooth mushroom? A popular representative is the lion’s mane, found at every other farmers market booth in L.A. Lion’s Mane is good for you. And I have just laid out pretty much everything I know about mushrooms, so thank you very much! Now, let’s move our attention to the seas, which during the Cretaceous were absolutely
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mollusk-city, for a few different reasons. In the most literal sense, if you think of ocean cities, you probably think of reefs. Today, reefs are constructed of coral. In the Cretaceous, many reefs were constructed of mollusks. I know—pretty unusual. Let me break it down. So, you know mollusks: huge group, includes snails, slugs, scaphopods, and also bivalves like clams, oysters, and—mushrooms? Nope,
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not mushrooms. Muscles. Got mushrooms on the mind now. Want some oyster mushrooms. Clams, oysters, mussels, etc. Bivalves have a very simple body plan—two of those shells, or valves, connected by a ligament. Bivalves are usually symmetrical, folded up nice and neat. But a new bivalve was stepping on the scene—the rudist bivalves, asymmetrical and very diverse. They generally had one valve attached to the ground or substrate, and the other one up in
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the water. They also had some pretty weird designs, like coiled or cone-shaped valves. Some looked like bullhorns. And to properly brace this body form, they liked to cluster together for extra support. This created a chain reaction—they could cluster the fuck up, and soon these formed massive rudist reefs. Knocked the corals out of dominance for a bit and looked cool as fuck. Looked like coliseums galore. This was the Roman Empire of the Cretaceous.
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Another point for Cretaceous mollusks were the soft-bodied cephalopods. What do you know, I left something out of the Jurassic. Octopuses seem to have evolved in the Jurassic. The earliest representative is Muellerianella—Muensterella scutellaris, a type of vampyropod, a group that vampire squids belong to today. And then octopuses evolved from there, at least that’s my understanding of it. Let me give you a little visual diagram.
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Let me get my whiteboard—I think this is going to come in handy in a second. Okay, so we have the coleoids. This whole thing is the coleoids. Up top, we have squids on this side, and on the other side, we have the vampyropods, which includes vampire squids and octopuses today. It’s important to know the split between squids, octopuses, and vampire squids. Vampire squids sound like they would be squids, but they weren’t—they’re more closely related to octopuses, as you can see.
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And so! In the Cretaceous, we start to see some of these shell-less cephalopods get massive, like Enchoteuthis. They were very big, but their size and general appearance over the years have been questionable. So, let me break it down. Obviously, soft-bodied cephalopods have soft bodies—the only thing that really fossilizes most of the time is their hard part, the pen, and that’s on rare occasions. Today,
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vampire squids and squids have pens, and they look different. So, if you have a fossil pen, you can kind of compare them between the two groups and see, you know, where it fits best. Early on, Enchoteuthis pens were compared to that of giant squids because they were massive, like the pens of giant squid. So, it was thought that the prehistoric Enchoteuthis looked like the giant squid and was also the same size, like 36 feet long, with a lot of
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that length coming from the tentacles. But then, the pen was compared to that of vampire squids, more closely related to octopuses. While the size was similar to that of a giant squid because they were both big, the overall shape was more similar to a vampire squid. So now, the general idea is that maybe this was a giant vampire squid relative, which meant their tentacles were likely not as long. Overall, they were probably around 10 to
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16 feet long, and that’s where the consensus is today. That might change, so. That’s all for that. Another point for mollusks are the ones you probably first think of when you think of Cretaceous mollusks. If you do think of Cretaceous mollusks. The ammonites! Last time, I mentioned that they get very big in the Cretaceous, so let’s just get that out of the way. Allow me to introduce you to Parapuzosia, one of the largest ammonites to ever exist, that we know of.
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One of the coolest things about these massive ammonites is that, unlike their soft-bodied brethren like Enchoteuthis, we are good on their size estimates. We’ve got that shit figured out because their shells are solid. You cannot question the fossil evidence—this is a bigass ammonite. If anything, they can only get more heinous. Maybe we're somehow underestimating the size of their tentacles. Maybe their tentacles were 50 feet long. There’s no way at this time to
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prove that they weren’t, but based on the shape of other ammonites and their similarly shaped living relatives, it’s safe to say their shell tells the tale. The shell itself was about 8 ½ feet long, and because their shells alone were so heavy, they are assumed to be not only the largest ammonites but also the heaviest invertebrates to ever exist, that we know of. You probably won’t be surprised to find out that these tanks are not my favorite
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ammonites of the time. No, that title usually goes to some unusual little guys this time called the heteromorph ammonites. Named as such because their shells go shit fucking all over the place—they are chaotic, and there are so many of them. They look like the products of an acid trip in Treasure Planet, the best Disney movie, by the way, and also the best video game, and they seem like they don’t make sense, like evolution
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couldn’t possibly have allowed this. But it did, and scientists have started to figure out how. I read this paper focusing on one specific group called Nipponites. [struggles] I’m just going to say Nipponites. Absolutely sick-looking, all coiled up in different directions, and really just looks like a thick knot. Sidebar: I don’t understand why people use big words just to use big words. Why are you making it harder for everyone? There’s no
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reason to ever use the word "deleterious," in my opinion—just say harmful or damaging, like the definition says. I read shit like that, I feel like a fucking caveman. So, if I’m understanding this paper properly, it seems that the strange shape of Nipponites and other heteromorph ammonites comes from the body and shell growing in different ways—different rates, directions, etc.—but they still technically grow symmetrically. It just gets all mixed up at
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different stages of growth. In figure 5, they start off growing pretty normally in one plane and then get all folded up, grow on a different plane, and so on, until they look like mush. But somehow it worked for them—they likely lived low-energy lives in the water column, slowly drifting around, facing upwards or horizontally, spinning around to feed on plankton. Heteromorph ammonites are cool. I suggest looking more into them. Check out Diplomoceras—they
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were like a 50-foot long paper clip. Check out other ones too, and tell me which is your favorite. Let me know if you like them! The last major event in the "No Bone Zone" was the Cretaceous Crab Revolution. Yes, this is finally the time when the peak body form rose to dominance—the true crabs in the group Brachyura. Technically, they first appeared in the Jurassic with the false crabs, the Anomura, following their
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lead not far behind. Crabs got going quick, and I recommend watching my video on it to learn more—it's my most popular video. But for now, just know that crabs really spread their wings in the Cretaceous, and now it is Crab City along with Mollusk City. And, it is also heinous Fish City. I have lots of fish to show you today, so let’s get into it! Stratodus, an eel-like fish, grew up to 16 ft long. But that’s just the beginning. Bananogmius,
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which had a sick name until it was renamed Pentanogmius in 2001 (a name I like a lot less),
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was Pentanogmius the whole time—that we know of. Next up, Protosphyraena, a massive, swordfish-like fish, but not a true swordfish. They got to about 10 ft long and were built for predatory speed, likely using their sword in a similar fashion to modern swordfish: slashing at prey, slicing it, stunning it, until it is suitable to eat. Then, another massive fish with a mouth like nobody’s business: Rhinconichthys. Not doing that joke— "A few moments later."
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Rhinconichthys nutz! (I was so high when I wrote that.) It was a parachute-mouthed fish that ate—you guessed it—plankton. They walked so the gulper eel could run. Next up, probably the most heinous and well-known Cretaceous fish of them all: Xiphactinus, also known as the X-fish. They were up to 20 ft long and had massive needle-like teeth, seemingly perfect for piercing flesh. But oddly enough, some
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fossil specimens of Xiphactinus show evidence of the opposite of piercing and ripping flesh. Yes, multiple fossil specimens of this fish have a fossil of a smaller, but still large fish that they have swallowed whole, which scientists interpret as the cause of their death from the smaller fish realistically being too fucking big to swallow whole, slashing around in there and damaging shit. For example, Gillicus, one of these said swallowed fish. Why would
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you try to swallow the fish whole? And for this reason, Xiphactinus, also known as the X fish, is also known as the gluttonous fish. There's only one thing scarier than a heavily armed fish, and that is a heavily armed fish who doesn't give a fuck and is also probably stupid. All right, moving on to some sharks. The first one I like a lot is the eagle shark, discovered recently in 2021. I remember making a TikTok about them when they were
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first announced because I thought they were so cool. They had bizarre wing-like fins, making them kind of look like a weird shark-ray mix, but they were in fact totally a shark. They're about 5 and 1/2 long, with a wingspan of about 6 ft, and a lack of teeth on the fossils suggests they were slow-moving gliders that ate plankton very serenely. Very serendipitously. "I don't understand why people use big words just to use big words."
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The next one is not that. Ptychodus. You might like what they got going on, but I do not. I specifically hate their mouth, actually, specifically their teeth. They were described by The Guardian as pavement-like teeth, which is just horrific. There's no need to make things worse. They're maybe more like smooth pebbles on a lakeshore, which, yes, sounds nice, but to me has no place in a shark's mouth. Like many prehistoric sharks, for a long time,
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the remains of Ptychodus were just teeth— all teeth, nothing else—until just this year, in 2024, when some exceptionally preserved fossils in Mexico were determined to belong to Ptychodus. Teeth and body displayed as one. As you can see in this photo, if you zoom in a little closer, you will see something out of a nightmare. Once again, the mouth. Here, it looks like that fake toddler skull that gets reposted every two days, but this time it's real, and it is profane.
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This mouth was nonetheless perfectly adapted to chewing unshelled creatures, and the new fossils suggest that rather than going for bottom-dwelling bivalves and crustaceans, they were more fast swimming, so probably went for creatures in the water column like sea turtles and ammonites. Okay, now moving on to amphibians. I'm going to be honest with you; this section is going to feel very short because it is. I only have one amphibian in this section to tell you about,
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but technically, I have two amphibians total to tell you about. I’m telling you about the other one later, in another bonus section that I haven't done before that I thought would be cool. And I'm going to keep it a surprise until then. So let me tell you about this first amphibian, Beelzebufo, also known as the devil frog or the frog from hell. Quite extreme, I know. It was initially thought to be about 20 in long,
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twice the size of the largest frogs alive today, making it the largest frog to ever exist that we know of. That turned out to be an overestimation. They're now thought to have been about 9 in long, so about the same size as today's Goliath frog. Nothing crazy, but they seem to have been capable of eating baby crocodiles and dinosaurs, which is still pretty badass. A frog eating a dinosaur? That is objectively cool. The seemingly largest frog that we know of will
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be coming in the next episode, as long as nothing changes, until then. So that's amphibians for now. Now let's see what's going on with the underdogs of the period: the mammals. Remember last time we kind of went through the whole family tree: the monotremes, marsupials, placental mammals, and some other groups that went extinct like the multituberculates, the docodon, etc.? So I figured I'd just give you some updates on the groups that are still around today, because
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it's really just the same shit as last time. Everything looks like a rat at the end of the day. So let's start with the monotremes, represented today by the platypus and the echidna. That's it. The mammals that lay eggs. Here's one from the Cretaceous, Teinolophos, the oldest and smallest monotreme that we know of. This is just so violently monotreme. You know, I feel like I have to bring them a jewel to unlock a quest. Let me pull them up. Yeah,
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I like what's going on here. You know what? They look like they should be a Webkinz, like that weird duck they had. It's called Googles. I guess it was kind of more of a goose, but it looks like it was designed based off of a platypus. It was a platypus this whole time. I guess that makes sense. I guess that makes sense. I guess that's why I said that. Anyway, back to Teinolophos. They look like the perfect mix between a platypus
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and an echidna. A platypechidna makes sense to me. And they were small, weighing about 40 g, or about an ounce and a half. They also likely had an electrosensitive or a mechanosensitive beak to help locate and eat insects, and I think that's pretty cool. Next, the marsupials. One of the earliest marsupials that we know of is called Deltatheridium, which sounds like an experimental drug. They just look like another rat, so let's
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move on to a bigger one. Didelphodon looked more like an otter than a rat and might have been semi-aquatic. They were the largest Cretaceous marsupial that we know of and seemed to have had the largest bite force relative to body size of any mammal ever, which is cool. This, along with other skull features, has led scientists to think they ate hard things, like maybe shelled creatures or turtles or crabs—potentially bones. Totally and completely badass. Oh, bones!
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All right, moving on to the placental mammals—our own grandmothers, grandfathers. Once again, a lot of rats. "You give a man a rat, you satisfy his rat desire." So I'm just going to show you some of the biggest. 125 million years ago, a cat-sized mammal was sinking its teeth into the ribs of a dog-sized dinosaur when the two suddenly became engulfed in a volcanic mudflow, cementing their position in rock for eternity.
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The mammal was Repenomamus, arguably the most famous mammal from the Cretaceous. They were about 10 lbs and kind of looked like a small badger, and they were attacking Psittacosaurus, the dinosaur three times its size that we'll talk about in a bit. Repenomamus is a clear example of the Cretaceous being more complex than you initially think it is. Yes, the mammals can generally be thought of as the underdogs, but nature never gives shit to you straight.
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Repenomamus was badass. One fossil specimen in 2005 was found with its last meal preserved in its stomach, which was baby dinosaurs. They were a big mammal for the time with a big appetite. For a long time, they were thought to be the largest Cretaceous mammals, until just this year, in 2024, a new largest mammal has been described from Argentina—one point for Gian—called Patagomaia, a bobcat-sized mammal that would have been around 30 lbs. Clearly, this is brand new,
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so all I have written down for this section is that they existed. More research must be done. Okay, so that was the mammals, the synapsids. Now let's move on to the stars of the show: the sauropsids. Let's start off with the snakes. Last we left off, there were some skull modifications going on from lizard to snake in the Jurassic, and the limbs were getting smaller. I mentioned when it came to losing limbs, the front limbs were first, then the hind limbs,
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rather than all at once, and that's exactly what we see in snakes throughout the Cretaceous. And about 130 million years ago, it seems as though snakes had lost their front legs, with evidence like Pachyrhachis, a marine snake alive during this time in what is now the West Bank (Palestine). They had teeny tiny little hind limbs, and their name means "thick spine" because they had thickened vertebrae and rib
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bones—adaptations that are associated with increased buoyancy in the water, which is what led scientists to believe that they spent their life in the water. And Najash. Alive much later, about 95 million years ago, still just rocking the two hind limbs. They were first discovered in Argentina once again in 2006, with very fragmented remains. But in 2019, scientists hit the fucking jackpot and found eight new skulls of Najash, including specimens that were nearly perfectly
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preserved three-dimensionally. Scientists were able to take CT scans and gain new insight into how the skulls specifically shifted through the transition from lizard to snake. Then, at some point around 70 million years ago, before the hind limbs were fully lost, there was a big split in the lineage between boas and pythons and other snakes. Now, boas and pythons are still born with remnants of hind legs—very small, so inside their body, but still there—which is pretty cool.
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Let's move on to the crocodilians. I haven't given a specific update on them in a minute. They were diversifying to shit; there were so many different crocodilian forms in the Cretaceous, so much so that some of them have been informally classified with names of other animals that they kind of have features of. I don't know if that makes sense, so I'll just keep going, and you'll get it once I start listing them off.
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First off, Anatosuchus, the "duck croc," was a crocodilian with a duck-like snout, very wide, hung over the sides. They were about 3 ft long and are assumed to have perused the waters to eat fish, frogs, and other aquatic creatures, using sensory areas on their snout to find meals. Next, Araripesuchus rattoides. "Rat?!" Yes, the "rat croc." Their teeth are reminiscent of rats and other rodents; they probably ate plants and grubs and used their rat teeth to dig them out of the ground.
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Next, Kaprosuchus, also known as the "boar croc," had features reminiscent of wild boars. They had three sets of fangs and kind of looked like boar tusks. They were about 20 ft long and seemed to have been semi-aquatic, with a snout suitable for ramming into things, perhaps competitors or prey or other things that need to be rammed. Next, Laganosuchus, the "pancake croc," was also 20 ft long, but this time with a very flat head
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reminiscent of a pancake, slender jaws with small pointed teeth lining the insides of them—a massive mouth. Outrageous, even. It seems like they'd have a hard time swinging it around, and that seems to be the consensus. Scientists think they were like the crocodilian version of a carnivorous plant, laying motionless, mouth agape for hours until prey stepped in and then snapped like a bear trap.
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I know it would kind of be my default to like the rat one the best, but I think this one is my favorite, and I do like pancakes, so I guess that checks out. The rest on the list don't have such descriptive labeling; they have more normal shit going on. They are arguably even cooler. So, first off, in 2020, scientists discovered some well-preserved crocodilian trackways in South Korea—not just a couple, but a lot
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of them. After measuring the length between each footprint, analyzing size, shape, etc., they realized they had trackways of a crocodilian that was 10 to 13 ft long and bipedal! Yeah, a croc that walked on two legs. They had footprints everywhere—footprints galore—with the details of toe pads and toe scales preserved, and not a single handprint. They've assigned this mystery croc Batrachopus, where now the reconstructions look like this.
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And that's all for now. Next, the most objectively cute croc on the list, Iharkutosuchus, was very small and likely ate plants. They had teeth set up to eat plants, jaw muscles, and orientations more suitable for plants, and I like that they had a very short snout. They are absolutely darling, if you ask me. All right, that was a palate cleanser just because the last two crocs on this list are just horrific. They happen to be the two largest crocs of the Cretaceous that
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we know of. Starting off with Sarcosuchus imperator, a very strong and dominant name, and for good reason—they're about 30 ft long, with an extremely long snout, and likely fed on a variety of creatures like fish, turtles, and dinosaurs. And whole. They likely ate them whole. And the next one, Deinosuchus, the "terror crocodile," another strong and dominant name. They are estimated to have gotten somewhere between 33 and 40 ft long and up
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to 10,000 lb. You might have heard of the classic crocodilian move they use to attack their prey, the death roll. They like to rapidly roll like that to dismember their prey. Deinosuchus seems like they were capable of performing a death roll, which is just heinous to think about—it would have just ripped you right in half. Fossils of Deinosuchus have been found all over North America and on both sides of what would have been the Western Interior Seaway
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throughout the Cretaceous, a massive body of water that cut right through the continent. To tell you more about it, I decided to bring on my friend Kallie, who you might know from PBS Eons. She's a paleontologist who just so happens to have been on a lot of digs in what would have been the Western Interior Seaway, so she's kind of a Western Interior Seaway expert. Also, she's my go-to paleontologist, and I actually just got to hang out with her for the first time
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in person a couple of weeks ago when I was up in Montana. She was showing me around Missoula, and we went to some breweries and got some food, and it was awesome. She's awesome—she's the best! So I'm going to hand it over to her now to teach you everything you need to know about the Western Interior Seaway. Kallie, take it away! Thanks Lindsay! All right, the Western Interior Seaway was a body of water that connected the Arctic Ocean with the
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Gulf of Mexico. It split North America into two island continents: Laramidia and Appalachia. But how did this happen? To answer this, we have to go back to about 180 million years ago when the oceanic Farallon Plate began sliding under the western edge of the continental North American Plate. As the plates scraped together, they kicked off a mountain-building event that created the modern Rocky Mountains. However, the subducting plate did something weird:
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instead of diving down into the Earth at a steep angle, the oceanic plate kind of stuck to the bottom of the continental plate and pulled down on the middle of North America. Plus, starting in the mid-Cretaceous, atmospheric greenhouse gases increased, raising average global temperatures and sea levels. Sound familiar? All this allowed water to slowly flow in, and around 95 million years ago, the Western Interior Seaway had fully formed. Roughly 5 million years later,
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the Seaway reached its maximum size. It had an estimated length of 3,000 miles from north to south, a width of 1,000 miles from east to west, and was probably 650 feet deep. So why don't I have beachfront property in Montana today? Well, the uplift of the Rockies continued, and eventually the oceanic plate broke loose, causing the continental plate to rebound, totally draining the Western Interior Seaway by the end of the Cretaceous,
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66 million years ago. But during its heyday, this warm, shallow Seaway was teeming with life. So far, over a hundred species have been described, including dinosaurs. That's right! The fragmentary remains of Hadrosaurus and Ankylosaurus-like Silvasaurus have been found in these marine deposits. But how? Well, these dinosaurs would have lived on land along the coast of the Seaway, and if they happened to die near the water, their bloated bodies could be picked up and floated out
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to sea. Once the gas bubble formed, the dinosaur carcass would sink to the sea floor, usually being scavenged on the way down. This process is lovingly referred to as "bloat and float." Now, there were other dinosaurs of the avian variety. Many of them could fly, but there were also several species of flightless birds, including Hesperornis. Hesperornis was fairly large, approaching 5 feet in length, and it had teeth in the beak bones that were solid,
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not hollow. It had useless tiny wings but powerful legs and webbed feet for efficient swimming. In fact, it was so specialized for swimming that it probably sucked at walking and was basically fully aquatic, only going on land to lay eggs. We also find fossils from another group that probably didn't spend a ton of time walking: Pterosaurs. These flying reptiles soared over the Western Interior Seaway, and one of the
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most commonly found is Pteranodon. This is the toothless one with the extremely long skull that has the pointed crest and a wingspan of up to 18 feet. A version of it was in JP3—if you know, you know! It's been suggested that Pteranodon was sexually dimorphic, meaning it had skeletal differences between males and females. Although not everyone agrees, there seems to be one type with a long skull crest, large body size, and narrow hips,
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and another with a short crest, smaller body, and wide hips, assumed to be the egg-laying female. Okay, so now that we've covered some of the life living next to, on top of, and over the Western Interior Seaway, let's talk about a few of my favorite animals that actually lived under the sea. Under the sea! Under the sea! Hey, Little Mermaid! Various types of bivalves occupied the seafloor, including clams. Some of the Inoceramid clams
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were truly gigantic, having a shell length of nearly 10 feet. Just like modern clams, these giants made pearls—big ones! The largest pearl known is 4.3 inches long and 2.5 inches in diameter. That's a little bigger than a credit card, only, you know, round. These giant clams were also death traps. At least nine species of small fish have been found inside clam shells, and it wasn't just one or two fish—there were many! A single clam was
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discovered with 104 fish inside. It's thought that the fish used the clams for shelter, possibly to hide from predators. But when the clam died, the shells would snap shut, trapping any unlucky fish still inside—a terrible way to go. What's more is that the fish are usually found crowded together in the most domed part of the shell because that's probably where the last of the oxygen was. Brutal. Another mass death assemblage is found among the crinoids,
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or sea lilies. They're related to starfish and sea urchins. Uintacrinus was a strange crinoids; instead of being attached to the seafloor, it floated near the surface like an alien hot air balloon. We think they lived in groups because often a bunch of them were preserved together, like this 6x4-foot slab that has more than 100 individuals. So they must have died at the same time! Can you imagine a swarm of Uintacrinus, each with 10 arms that were 3 feet long,
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acting like some kind of armored jellyfish from a Lovecraft novel? No, thank you! No, thank you. Part of me also thinks that the biggest, baddest predator of the Western Interior Seaway would have also avoided blooms of Uintacrinus. This would be none other than the mosasaur Tylosaurus. One of the largest specimens, nicknamed Bunker, has an estimated body length of at least 40 feet and had a skull that was 5.6 feet long—that's how tall I am! Can you imagine an animal with a skull as
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long as I am tall? Incredible! We even know what its scales looked like. Skin impressions show that Tylosaurus had small, diamond-shaped scales with a ridge down the middle, similar to a rattlesnake. As the Seaway's apex predator, this beast could eat basically whatever it wanted. In the preserved gut contents, paleontologists have found fish, sharks, turtles, Hesperornis, plesiosaurs, and other mosasaurs, so these things were like cannibals too! The only things definitely too
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big to eat were the giant sea turtles, but Lindsay will tell you more about those. Another animal that lived in the Western Interior Seaway was Archelon, the biggest turtle to ever exist that we know of. They were 16.5 feet long, so about the size of a 2011 Dodge Durango—a car I used to have. The sound system was solid, but then it turned out to be a lemon, and Aralon was a very massive lemon! They had hooked beaks and probably
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a very strong bite to feed on ammonites and squids—other mollusks of that variety. Now, what's going on with the Plesiosaurus? Last time we left off at introducing you to Pliosaurus, the Plesiosaurus that emerged from the Jurassic, that had short necks and big heads. They continued doing their thing, being apex predators of the seas and getting over 30 feet long, like Kronosaurus, which got to 35 to 40 feet long. They had massive jaws and teeth that could each get
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to a foot long. This godforsaken mouth could rip apart anything it wanted in the ocean, like fish, ammonites, and even other marine reptiles of the time, like Elasmosaurus. Some of the long-necked Plesiosaurs were found in oceans all around the world, and some of them had long necks, like Albertonectes. They were 39 feet long, with a neck that took up 23 feet of that length. When you
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see them all sprawled out, it is just ridiculous! Here they are compared to an average-sized family, in case you needed that visual tool. Their necks were made up of 76 vertebrae, making it the largest neck of any elasmosaur that we know of. Not surprising at all, other elasmosaur didn't have such elongated necks, like Aristanectes—a much more respectable neck, if you ask me! Fewer and shorter neck vertebrae make it much more sturdy and less susceptible to decapitation.
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I don't know how evolution allowed Albertonectes to even get there in the first place, but shit happens. Now, let's move on to the Ichthyosaurs. What's going on with the OG dolphins? Honestly, not great things compared to previous periods. Their diversification slowed down a lot, and eventually, they went extinct about 100 million years ago. Have you noticed a lot of things happen around 100 million years ago? That's the split between the early and late Cretaceous,
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just so you know. But I don't do shit in that order, 'cause I don't like it. It's interesting because they went extinct way before the asteroid even thought about hitting the planet. This happens: groups go extinct sometimes not because of a mass extinction event or a catastrophe, but because they can't keep up with competitors. They can't adapt fast enough; they just slowly die over time. A lot of those changes happened 100 million years ago,
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which is why the split between the early and late Cretaceous exists there, and it's nice. It's a nice number—100. I like it a lot. Anyway, the Cretaceous Seas were no fucking joke. Obviously, we had some crocodilians on the shores, pliosaurs with big appetites, and we also had the appearance of another group that quickly rose to domination: the mosasaurs. You are definitely familiar with them from Jurassic World. Obviously,
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another animal that was not Jurassic. I do want to point out they were a lot bigger in the movie, but in life, they were still massive. The largest got to about 50 ft long. They didn't really show up until the mid-Cretaceous, and the general consensus is they evolved from terrestrial lizards, which is fucking insane. Just popped the fuck off and took over the whole world, becoming apex predators, some becoming specialized divers like sperm whales. They had different teeth
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setups—some for catching fish and squid, others for harder shells like ammonites and turtles. Their mouths were ludicrous; they had a second row of teeth on the roof. One species, Xenodens, had weird-looking teeth like a saw, likely used to scavenge or cut chunks out of larger prey, 'cause they were little guys—like 3 ft long. There were also freshwater mosasaurs like Pannoniasaurus. They were the first freshwater mosasaur ever found; they got to about 13 ft long
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and were likely apex predators of the no-salt zone. Unlike marine mosasaurs, Pannoniasaurus still had legs, so maybe they could have ventured onto land from time to time. And of course, the belle of the ball, star of the show: Mosasaurus, the classic red-blooded All-American heartthrob—well, European as well. They were top of the food chain: shark in the water, viper in the grass, apex predator, getting up to 56 ft long. They ate literally anything they
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wanted, including other mosasaurs, and potentially ventured into deeper waters for giant squid, with the help of a shark-like tail that propelled them through the ocean. Totally and completely badass. So that was the waters. Now let's move our attention to the skies: the pterosaurs. Last time, I had some cute pterosaurs to show you and told you about some general trends. This time, I'm going to be honest: I did not really come prepared with general Cretaceous pterosaur
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knowledge or development. Really, all I have is a list of the most grotesque creatures I've ever laid my eyes on. I'm expecting you to have a very visceral reaction to the sight of them. So I'm going to go in order from the least to most extreme, in my opinion. So number one: Barbaridactylus looked like a classic pterosaur with an extremely long and thin Mohawk. Of course, that is not a concoction of hair and 99% gel; that is a headrest made of bone. This was the
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perfect shirt to wear. Here's a related one: Nyctosaurus, an even more badass headrest if you ask me. They're both nyctosaurids, and they both belong in a punk band made up of 40-year-olds that still live with their parents called "This House is a Prison." There's a lot of hypotheses for the purpose of these crests—maybe species recognition, thermoregulation, flight stability, display. It was probably multiple
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things and different things depending on the species, as you will see. They are probably some of the craziest shit you'll ever see in a prehistoric context. Next up is Quetzalcoatlus. Not so much heinous in headrest, but more so heinous in everything else. They were up to 16 ft tall standing on the ground, with a wingspan of up to 36 ft long, making them the largest flying animal to ever exist that we know of.
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I know what you might be thinking: that body form does not seem suitable for flight. Their built confused scientists as well for years. They had extremely long skulls and necks with very small torsos and legs. So how the fuck did that work? How did even taking off from the ground work? Well, this question was answered in 2021. Scientists figured out they must have crouched and leapt 8 ft into the air
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for their wings to clear without hitting the ground and then took off from there. Quetzalcoatlus belonged to a specific group of pterosaurs called the azhdarchids. They all took on a form that makes you sick to your stomach, but you can't look away from. Another big one is Hatzegopteryx. Technically heavier but shorter than Quetzalcoatlus, so it is also considered the largest flying animal by weight that we know of. Next!
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I think I've made my point. What if I just stop the video right there? There were also dinosaurs, then the asteroid hit, then they all died. Stay curious! The world has a lot for us to learn. Cya! Just kidding, I would never do that to you. I at least hope that this video so far has shown you that the Cretaceous was much more than the dinosaurs. I mean, Jesus Christ, we must be like 40 minutes into the video by now, at least.
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So, as we're finally getting into this section, I just want to say—and I know you already know what the fuck is going on—but it's never been more true than it is right now: I can't possibly cover all the dinosaurs. It's physically not possible for me to do at this moment in time. So I have created a little sample plate for you, which includes some of the ones I knew before, as well as the strange specimens I found while researching—the strangest I could find, just for you.
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And also, I have a very cool announcement! In honor of finally reaching the Cretaceous dinosaurs, I've partnered up with my friend Matt to create a famous fossils puzzle featuring some really well-known Cretaceous dinosaur fossils, along with marine reptiles and more throughout the Mesozoic—fossils like Dueling Dinosaurs, Borealopelta, etc. Matt and I have a lot in common; we both spent time at OSU in Corvallis,
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and we both have a passion for the natural world and science education. His format is puzzles and games—ones that build food webs or protect different biomes—and we decided to collaborate for his next project to put you in the mind of a paleontologist, teaching you about these fossils as you piece together which bones belong to which fossil. Some parts are distinguishing dirt from fossil impressions. Honestly, it's a fucking hard puzzle,
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just like the work of a paleontologist! When I was at OSU during finals week, I started doing puzzles with my roommate as a break from studying. It felt good to focus on something that was fun but still challenging and rewarding—that wasn't my finals. Now, I started to do that as a break from research for these longer videos, so I'm really happy now to be able to combine to offer you a sick puzzle that merges both
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mine and Matt's goals for our content to create a fun way to learn authentic science. So go to his website to grab a puzzle—it's montrosebiology.com right here. The puzzle is $30 with free shipping in the US, and as you add more to the cart, you get a bigger discount, so that's cool. I'm excited for you to check out this puzzle, and I really hope you enjoy working on it. I really liked it, and now it is going to make for some great decor for my home.
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Now let's get back to the dinosaurs. We're going to start off with the group that arguably has the most dramatic morphological changes from the last time that we know of—the ones who really showcase why the Jurassic was so different from the Cretaceous: the Ornithischians. Turns out I pronounced it wrong last time—Ornithischians! Shout out to Kallie for letting me know. Okay, the Ornithischians. You might remember I said it includes everything that is not a
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sauropod (the long necks) or a theropod (the kangaroo stance). So when you think about everything that could include, it's quite a fucking long list. Let's first run through the group we remember from last time: the armored dinosaurs, the Thyreophorans—the group Omar took care of last time. In the Jurassic, this included the Stegosaur form, the most iconic of the time, and the Ankylosau formr, like Gargoyleosaurus. By the time the Cretaceous period came around, the Stegosaur got
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booted, and the Ankylosaur was on top, with some insane neck spines like on Sauropelta. No wonder the Ankylosaurs were able to stick around; those bitches are lethal! Horrifying. But what might be even worse is the fact that they didn't evolve for no reason, you know? Nothing does. The stresses of their ancestors' environment required them to have two swords and several daggers strapped and ready
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to go at all times—stressors like predators that could get around anything less than that. Ew! If I got stuck in the Mesozoic and could only have one thing, it would be a shotgun. But, of course, my favorite Ankylosaurian of the time is Borealopelta, which was described through probably the most beautiful fossil I've ever laid my eyes on. It gives me chills, and I've only seen pictures of it. When I see it in person, I'm going to cry! It's in my coolest
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fossils video if you want to learn more about that fossil. But for now, we're going to move on. Objectively, the cutest Ankylosaur of the time was Minmi—cutest name as well! They got to about 10 ft long, and that's all I have to say about that. The rest of the Ornithischian groups I have on the list are brand spankin' new, first appearing in the Cretaceous, like the pachycephalosaurs, known
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for their unusual bumpy heads. At first glance, you might think the big bump was an indication of a large brain size, Jimmy Neutron-type build. But no, quite the opposite. Their name translates to "thick-headed lizards." It's literally just a thick skull. As a matter of fact, a very thick skull! Maybe they used it the same way some animals use their horns—to headbutt their enemies—or maybe just for display. They got to about 15 ft long, which might sound pretty small
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compared to other dinosaurs alive at the time, until I introduce you to micropachycephalosaurus. Micropachycephalosaurus is a very small dinosaur, about 3 ft long, with the longest dinosaur name—about 23—not about—exactly 23 letters. They hold the record as of right now, on Thursday, October 10th, 2024. I wouldn't be surprised if someone swooped in sometime soon to change that. Maybe Supermicropachycephalosaurus is being unearthed as we speak!
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The next group is one that generally doesn't sit right with me: the Hadrosaurs, also known as the duck-billed dinosaurs. I've talked a lot about animals with their overall build; they look like a walking obtuse triangle, which just makes me a bit uncomfortable. Despite this, as it turns out, I went fossil hunting twice this summer for the first time ever, and the first fossil that I found—I found it, I dug it out—was a piece of a hadrosaur jaw, and I
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have it here today. Check it out—nice! I started cleaning it a couple of nights ago. I have a handful of bones that I was able to bring back. I was going to send them to somebody to clean them, and the other night I was like, "Well, why don't I just try cleaning them?" So I messaged Kallie and asked her if I could clean them with a toothbrush, and she said yes! So there's still a lot of dirt on it; I think I should probably get some professional tools. But,
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you know, I'm just working with what I've got for now. So that's that! I had a lot of fun this summer; I went from never touching a fossil to touching probably 20, so who knows how many I'm going to touch next summer? That's all to say, Hadrosaurs—I may not understand them, but I do respect them. I respect the fact that ones like Shantungosaurus make me realize I need to expand my vocabulary because "grotesque" doesn't cut it. They got to 50 ft long. That's too big,
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in my opinion. I think that size should be roped off: sauropods only. But this next one I like: Parasaurolophus. Their head crest is pretty cool and is what they're famous for. It is hollow, like a wind instrument, and just so happens to connect to their nostrils. So in the '90s, scientists blew air through it to see what it sounded like and maybe get a gauge for what it sounded like in real life. Today,
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I have a clip of what that would have sounded like for you. Gian, roll the clip!
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Like a bellow for war—probably not entirely accurate, 'cause who knows what else was actually going on—but cool to imagine nonetheless. Another one of a similar style is Tsintaosaurus, the Hadrosaurid unicorn. Kind of. Fossil evidence suggests they lived on the edges of lakes in herds and had massive tails to help them swing. Obviously, their head crest is nuts, and initial reconstructions had them looking like they could emit a radio
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signal. And you know the unicorn reference. Then later fossil evidence revised it a bit, making them look more like a French chef. So, they definitely kind of look like Parasaurolophus, but did not seem to have the same wind instrument setup. Their head crest was hollow but not connected to the nostrils, so there's no telling what they sounded like at all. And the last hadrosaur, another similar head crest setup, is Lambeosaurus,
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which looks like a misplaced mitten. Now we're going to move on to the Ceratopsians—the horned dinosaurs. You know them; you love them for the face horns and the frill. The frill is the coolest part, in my opinion, and in many ways, it's very Renaissance. Its purpose is not completely understood; it might have been for defense, display, thermoregulation—the usual shit things might be for the dinosaurs. The most iconic Ceratopsian is the one and only Triceratops,
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one of the largest ceratopsians at up to 30 ft long and definitely the most iconic—probably the second most iconic dinosaur of all time. They were pretty cool looking, but there are a couple of others that just blow them right out of the water, like Styracosaurus. Their frills were objectively sick! When I first saw it, I was like, “Damn, that is definitely my favorite ceratopsian!” But then I saw Diabloceratops—that is one sick son
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of a bitch! Very regal in a dark way. They look like they would listen to Lorna Shore. Another cool one is Lokiceratops. They had massive curving horns on the back of their frill that were like blades—the largest frill horns found on a horned dinosaur ever. And then there's Einiosaurus, the Squidward of ceratopsians, and Psittacosaurus, the one I mentioned earlier and the most unusual ceratopsian. They belonged to a
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larger family of ceratopsians with no horns, a small frill, and a beak called Psittacosauridae. My least favorite family member is this one; it looks sticky. All right, now moving on to the Sauropods—the long necks, the big boys! When you think of Sauropods, you think of a very specific template, and it looks like this. Many Sauropods look this way: pretty basic body form. And as I recall, many of you were shocked to find out that in the Jurassic,
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this accent existed as well—the tail spikes. An exciting development in the Cretaceous; there's a lot of this, but there's also this, like Bajadasaurus, a relatively new sauropod known to science with the most metal hairstyle I've ever seen in my entire life. This guy needs a drum set! I feel like I can put together a reasonable Cretaceous band. I would say Bajadasaurus on the drums, obviously; T. rex on the mic, since they can't do anything else;
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an Ankylosaur on the keyboard; Nyctosaurus on a seven-string; maybe a Nipponite on the bass, or no, maybe Quetzalcoatlus with an unexpected electric stand-up bass. They sound like a mix between Creed and Rezz, and they're terrible! Bajadasaurus did not have a mohawk, though. Once again, this is not a mohawk; it is bony neural spines, to be exact, that point forward permanently. Seemingly as defense, they might have been in more of a
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sail configuration—hard to say—which might be for thermal regulation or display. They were first described in 2019, so more research needs to be done on them and stat, in my opinion. Another similar one is Amargasaurus, which looks like Bajadasaurus walking against the wind. Both are from Argentina, so two more points for Gian! I think these are my favorite Sauropods I've ever laid my eyes on, but we're only near the beginning of the list, so let's see what's next.
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Picking up the whiteboard, I've made quite a mess. All right, this time we have this—yeah, armor like the Ankylosaurus. Allow me to introduce you to Saltasaurus, another Sauropod from—you guessed it—Argentina! What's crazy is I did not do this on purpose; Argentina is just undefeated in weird Sauropods. Well, let's move away from Argentina for a second so I can show you—just redo this neck—this! Now, what do I mean by this? This Sauropod has a wide mouth shaped like a duck,
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and inside of it, there were 500 replaceable teeth! Nigersaurus, found in—you guessed it—Niger. Why 500 teeth? Who fucking knows, dude! But their mouth was built for the feeding style of a cat. So, not even in the treetops, which Sauropods seemingly evolved to reach with their long necks. But just another example of nature never giving shit to you straight. All right, the next one is a bit more Bohemian avant-garde. Possibly not a valid species,
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but crucial to include nonetheless. Now, what do I mean by this? Brontomerus, whose name translates to "thunder thighs," was found in Utah in 1994. They have leg bones that seemingly would have supported the most robust thighs of any Sauropod that we know of. But for what? Possibly to kick enemies, maybe stomping them to death, or maybe just to walk up and down a lot of hills. I'm sure anyone that lives in San Francisco has a pair of thunder thighs themselves!
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From my understanding, the fossil specimens were pretty fragmented, and unfortunately, the site they were found at had been looted by some fossil-hunting bandits. So, it's hard to say if this is a new species without more fossil evidence, but it's currently loosely classified as one. Those thighs are one of a kind, but that might change in the future. So, those were some Sauropods with a variety of traits. Others came in the classic template
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form but in a variety of sizes as well, like Magyarosaurus, a 20-foot dwarf Sauropod found in what is now Romania. At the time, this would have been situated on an island—Hateg Island. So, yes, bitches! This seems to be another classic case of islands rule. You might remember I talked about it in the Homo floresiensis video, the Hobbit people. Islands rule is Mother Nature's way of saying, “Fuck around and find out.” Islands are where shit gets weird!
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In general, the smaller an island is, the weirder it gets, and the further it is from the land, the weirder it gets. Maybe fewer or no predators, less competition, and populations are genetically isolated. So, over generations, their evolution just goes nuts! Big animals get smaller, small animals get bigger, and a whole variety of changes in between. And so, for this reason, it seems Magyarosaurus got small. They were one of the smallest Sauropods of the time that we know of.
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How about the biggest? With another point to Gian, allow me to introduce you to Argentinosaurus, from—you guessed it—Argentina! They were a type of titanosaur, generally the largest Sauropods of the time and the biggest animals to ever walk the planet that we know of. Argentinosaurus seems to have been the absolute biggest, with a max length of 130 ft long. Another titanosaur of a similar
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size is Patagotitan, also from Argentina, and Puertasaurus, also from Argentina. We would have looked like ants next to these behemoths, and I personally wish they were still alive today! I want to show you this picture, which is insane and might make you want to throw up! Their size was probably a great defense against the predators alive at the time, which in general mostly belong to the last group on our list: the Theropods,
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the bone-chilling, teeth-chattering beasts of the Cretaceous Approximately. It's really just a stereotype—Hollywood propaganda! The Theropods popped the fuck off during this period in a variety of ways, the existence of T. rex alone, of course! But Theropods also spread out in terms of size, lifestyles, etc. And so, I decided for the last group of dinosaurs on the list to show them to you from smallest to largest for the suspense of it.
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So first, allow me to introduce you to Falcatakely, yes, a bird! I'm pretty modern-looking compared to what we left off with in the Jurassic. They're about the size of a crow and had a beak like a toucan. Another small Theropod is Anchiornis, a close relative to the birds and more similar in appearance to the Jurassic bird builds. They had not only wings on their forelimbs but also on their hind limbs, just like the slightly larger Microraptor that
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got to about 3 ft long. Their four wings allowed them to be capable of gliding and possibly flight. In 2012, scientists analyzed a really well-preserved fossil from China that had preserved melanosomes, which are essentially little tiny pigment packets. Different patterns of melanosomes in fossils indicate different skin colors in life, and the patterns in the Microraptor fossil point to an iridescent black look—very chic!
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Preserved melanosomes are sick; they’re very hard to come by, but when they do, holy shit! And it just so happens my favorite example is the next on the list: Sinosauropteryx, about three and a half feet long and the first non-avian dinosaur that scientists were able to figure out the coloration of. Honestly, I think I'm due for a part two of the coolest fossils; this will be at the top of the list. This was also the first time feathers were found
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on a non-avian dinosaur, so this fossil just has it all. It is just the best! By analyzing the melanosomes found in the fossil, scientists found that Sinosauropteryx was a reddish-brown color with a striped tail and a lighter underside. Very cute! I like that they existed. All right, next on the list: Incisivosaurus, named for the incisors that made them look like a rodent. They’re about 4 ft long and ate plants. This picture makes them look British!
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Next, Velociraptor—one of the most misunderstood dinosaurs in mainstream media of all time. You're probably most familiar with Velociraptor as this 6 ft tall ruthless killer that taps their toe claws on the ground to locate children suitable to eat. This, once again, is all Hollywood propaganda because they actually looked like this—about the size of a turkey with a long tail. They probably kept their sharp claw off the ground to keep it sharp. If I have disappointed you today,
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I'm sorry, but maybe that just means I have to give you a new favorite dinosaur, and maybe it'll be the next one on the list: Concavenator, the camel from hell. They got to about 20 ft long, so we're jumping up a bit in size. To me, they look ridiculous, which is why they made it on the list. The bump is thought to be a sail-type situation, helping to thermoregulate or identify each other. For now, it's a mystery!
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If you watched my T. rex episode of Junkspiracies or if you're a Theropod sommelier, you'll know that Theropods experimented with different size ratios: small head, big arms; big head, little arms; and it got out of hand with animals like Carnotaurus, whose arms seem completely useless. You might recognize them in their recent breakout role in Prehistoric Planet, where they showcase really the only possible function of the tiny arms: to pick up chicks. But don't let them
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fool you; these animals were clear-cut certified predators. They got to 26 ft long and had powerful leg muscles built for speed, possibly able to run at 35 mph. This is an aerodynamic design! The size ratio experiment went to the other side too, like I said, with big arms and a little head, and once again, it got out of hand with animals like Gigantoraptor, a wicked beast. They got to 16 ft tall and 26 ft long and seem to have enjoyed a plant-forward diet,
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much like another one on this heinous side of the list: Therizinosaurus. They got to 32 ft long and had godforsaken claws that got to 3 ft long. Three feet long claws, dude! It might be shocking to find out they weren't used to rip their prey to shreds—unless they were ripping plants to shreds—but nobody knows. Claws are a big mystery! Some scientists have evidence that points to defense. Early studies suggested maybe digging and digging things up, and the most recent studies
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suggest they were pointless and only served as decoration. More research must be done! Another one that is also similarly wretched, like the last two: Deinocheirus. Dude, what the fuck is this? Their name means "terrible hands," which is true—they're just terrible! Each one was almost 8 ft long, making them the largest arms of any Theropod that we know of. They were 16 ft tall and 33 ft long. They also ate plants, but fossil evidence of fish scales in
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one specimen's stomach suggests fish were part of the diet too—unless that was an accident. The next one on the list is technically T. rex, which got to about 40 ft long. I had to mention them, but I'm not going to talk about them because I just did a couple of weeks ago, and everyone knows what the fuck is going on with them. This is THE dinosaur. It would be like telling you what a dog is. And because
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the last one on the list is going to be a shit show, I would rather just get it over with: Spinosaurus. I can't believe I'm saying this, but I have to talk about Spinosaurus. I've said before I would never talk about Spinosaurus. "The Spinosaurus fandom scares the shit out of me! I refuse to open that can of worms. I'm not doing that shit." But now I have to, and there's no way out of it. Spinosaurus is that one dinosaur you wouldn't
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touch with a 10-ft pole. Shit with them gets updated like every 2 weeks—not little things like what color their toes were, but complete lifestyle shifts. An absolute diva of a fossil! The story of their discovery over the length of like a century alone makes them the most dramatic dinosaur to ever exist. It involves a World War II bomb, a search for an unidentifiable man in Morocco. It's a story of love and loss, and one that I might make into a whole Spinosaurus species spotlight
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video in the future. Might, but not today. I'm not jumping right into the deep end near the end of a History of Life episode. I'm just not. I'm just keeping it as simple as possible right now. Spinosaurus was definitely a predator and is the longest predatory dinosaur to ever exist that we know of. It got somewhere between 40 to 50 ft long. It was thought to walk on two legs, then it was concluded to walk on four legs, then it was concluded to swim,
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then dive, then not swim, then swim, then walk on four legs on land, and also swim, then not swim. It's probably going to be outdated by the time you watch this. Before we get to the asteroid, like I said, I have a little bonus section for you. Cretaceous dinosaurs are the most iconic extinct animals in our eyes, and when we think about them or see them represented in media, they're often placed in tropical or temperate environments. We think
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of them in rainforests and jungles. While that is true for most of them, there were also some that lived in the extremes at the poles. I mentioned at the beginning of this video that there generally wasn't ice at the poles; they definitely weren't as cold as they get today, but they were still harsh environments to adapt to—some snow, as well as months and months of complete darkness in the winters. Harsh and depressing as shit. So I wanted to highlight
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these regions for the video. Technically, it's a section that probably belongs in every episode. Life has always existed at the poles, and we kind of just don't think about it. But with the dinosaurs specifically, it's a piece of information that kind of smacks you in the face when you first hear it. At least it did for me. Like, duh! Dinosaurs must have lived at the poles, but I never thought about it before, ever. And now I need to know everything!
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We're going to start with—mmm, the South Pole during the Cretaceous. Remember, we had the start of that final breakup of Laurasia in the North, Gondwana in the South. Parts of Australia, South America, and Antarctica were in the Antarctic Circle. So Teinolophos, that monotreme I mentioned earlier, was technically in the Antarctic Circle, as well as their relative Sterepodon, who was just fully platypus in form and shape. It's probably not surprising that mammals were
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in colder latitudes; that's their thing! They thermoregulate and can live at the poles. Well, like I mentioned before, I had saved a second amphibian for the bonus section, and it turns out to be one that lived in Antarctica: Koolasuchus. Such a sick-ass name! Sounds like they were named by some random guy in Venice Beach. They were also alive in Australia, arguably the Venice Beach of continents. They were named after the woman who prepared the fossil,
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named Leslie Kool—a very cool name! It also works because Koolasuchus lived in a cool climate, so double whammy! They were actually one of the last temnospondyl amphibians on the planet that we know of. Remember that more ancient lineage of amphibians that was getting replaced by the more modern amphibians, the lissamphibians? Koolasuchus clung on for dear life! It was likely only able to survive by living in a cooler environment that
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other amphibians weren't really down for. They were 10 ft long and had mouths lined with 2-in long teeth and preyed on turtles, fish, and possibly small dinosaurs in their habitats. There was also Morrosaurus, alive in what is now Argentina, and another dinosaur, Leaellynasaura, shows evidence of burrowing to escape the cold. There were also some plesiosaurs in Antarctic waters, like Aristonectes, which I mentioned earlier, and Morturneria, whose face I don't
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like very much.They were filter feeders, which is why they looked like that, sifting through sand to trap small creatures in their mouths. A horrific way to go, if you ask me–in this mouth. All right, how about the North Pole? There's lots of evidence for different ways animals adapted to the cold and darkness there, like migrating Edmontosaurus. There’s evidence of migrating in herds, traveling south for winter to escape the cold. They're about 40 ft long,
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so heinous in size. To put that into perspective, here's an actual picture of me holding an actual Edmontosaurus metatarsal, which to us is a little toe bone, and on them is that little bone right there. Look how big that little bone is compared to me! Also, I'm 5'4" by the way. I know you think I'm smaller in relation to other things around me, but my cat just so happens to be big, my base is abnormally long, my clothes are also just very big, and my ceilings in my
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last place were also unusually tall. I'm 5'4". I am the average height of the American woman. But anyway, while some species might have migrated, others stayed during the dark months, like Pachyrhinosaurus. This is a picture of me holding a Pachyrhinosaurus bone at a Pachyrhinosaurus site. Did you see the news about the big Pachyrhinosaurus skull they excavated? I was there when it was still on the ground. So anyway, the growth rings in their bones suggest they grew rapidly in
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warm months and stopped growing in cold months. A helpful adaptation, if you ask me! That way, you can save energy, not using it so much on growth. Possibly the coolest polar species is a Tyrannosaur called Nanuqsaurus, which means “polar bear lizard.” They got to about 22 ft long—so much smaller than other Tyrannosaurs like T. rex. This is thought to be an adaptation to harsh polar environments. It seems kind of opposite to what
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we think of with mammals today, which generally get larger closer to the poles. But different factors impact different groups differently, so it's not known for sure, but that's the idea. Clearly, the dinosaurs had an insane run—180 million years of domination in every part of the food chain at every latitude. But on one spring day, 66 million years ago, it ended. [explosion] When a 7-mile-wide asteroid pummeled into the coast of what is now Mexico.
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It exploded on impact and had the pressure of a million hydrogen bombs, and liquidized the ground it blasted into, shooting it up 7 miles into the sky from the rebound before disintegrating back onto the ground. The impact led to a mega tsunami, with waves nearly a mile high, sweeping across the planet in every single direction. The explosion created a crater that was 110 miles across and 12 miles deep. All that ground was shot up into the air. The larger pieces started raining
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down as flaming debris, broiling the surface of the planet, and the smaller pieces were settling into the atmosphere, forming this huge cloud that started growing across the planet. Just like the mega tsunami was sending ripples everywhere, tsunamis reached every single shoreline. All of this was happening in the same day! It was unimaginable chaos in the most extreme sense. And that's not all! At the same time, on the other side of the world, there were volcanic
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eruptions in what is now India. Yeah, everything everywhere was horrible—spewing lava everywhere, sulfur into the atmosphere, with the rest of the debris particles. Everything that somehow survived the million disasters that came from the impact itself was suddenly faced with an ecosystem collapse from the ground up. The clouds were thick enough to reduce global sunlight for years. Plants couldn't survive, and that sent a domino effect through the food chain. This
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extinction sounds like a fairy tale or a kids' storybook. The dinosaurs, marketed in the same vein as dragons and wizards, were wiped out by an asteroid. It literally sounds like sci-fi; it sounds too good to be true—or I guess too bad to be true. But somehow, it is. Scientists have a shit ton of evidence, so let's run through it. I said that the explosion of the asteroid created a huge cloud of flaming debris that fell back onto
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the planet. The contents of that debris included iridium, an element that's very rare on Earth but very common in asteroids. Iridium has been found in a thin layer all around the world, always corresponding with the date of the extinction, 66 million years ago, which led scientists to hypothesize that an asteroid impact wiped out the non-avian dinosaurs. Later, that was supported with the discovery of the crater in Mexico. How the fuck
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do you pronounce that? Actually, just put the name up right here; I'm not pronouncing that. It's buried under soft sediment, but its shape is still held by granite that forms from the impact. Scientists found it by mapping the strength of the gravity field over the area and have since been able to access it by drilling into the sediment. Since the flaming debris broiled the planet's surface, the iridium layer found all over the world is
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often followed by a fire deposit where the land was literally burnt to a crisp. The massive lava flows are now known as the Deccan Traps in India, and scientists have run tons of studies on how the ocean water would have flowed across the globe from the impact. It seems too bad to be true, but somehow it is. The animals that survived were ones that could go long periods without food or survive on small amounts of it. Lots
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of seed eaters were able to dig them out of the ground. Seeds are always on top, and this paved the way for those small, seed-eating, ground-dwelling rats of the Mesozoic to get the advantage, which we'll talk about in the next period. This is the end of the Mesozoic Era, so if you liked it, be sure to subscribe so you don't miss the next one. And if you like how long this video was, let me know and also give me a like. I would
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appreciate it. Thank you, Helix, for sponsoring this video! Check out the Famous Fossils puzzle; let me know if you like that as well. Thank you so much to Kallie for coming on. Check out Eons if you haven't already. Keep up with behind-the-scenes content and my Discord server on Patreon. And for now, stay curious; the world has a lot for us to learn. Cya!
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Holy shit, I can't believe I did that all in one day! Odie believe we did this in one day! One day, one day! He's purring—he's like, "Why the fuck did you stop?" Ow! Don't bite my nose!
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