ExtinctZoo - When A Sea Dried Up And Left Hell Behind (literally)

Episode Date: April 26, 2025

Imagine a place where the deadliest waters laid, and then imagine that in the exact same spot the deadliest land also rested, well turns out that really happened, let me explain...

You said this place was steps from the water. We just haven't found the steps yet. How much did we save? Enough. Enough to get lost. Or you could book a stay with Hilton. Welcome to your ocean front room. Just steps from the water.

The Hilton sale is on now. Book on Hilton.com or the Hilton app and save up to 20% to get the stay you expected. When you want savings, not surprises. It matters where you stay. Hilton, for the stay. No one goes to Hank's for his spreadsheets. They go for a darn good pizza.

Lately, though, the shop's been quiet. So Hank decides to bring back the $1 slice. He asks Copilot in Microsoft Excel to look at his sales and costs. To help him see if he can afford it. Co-pilot shows Hank where the money's going and which little extras make the dollar slice work. Now, Hanks has a line out the door. Hank makes the pizza.

Co-Pilot handles the spreadsheets. Learn more at M365Copilot.com slash work. Have you ever wondered why we call some creatures in the water sea monsters, but we don't call things on land, land monsters? Well, there's probably a good reason for that, which is that the waters of Earth, not the land, hold the most terrifying, mysterious, and sometimes unbelievable predators, that usually always out nightmare their terrestrial counterparts. And because there's been life for around 4 billion years, and everything is constantly changing, it's only natural that tons of scary and frankly twisted, oceans, seas, and their inhabitants. have come and gone. But in the end, only one can take the crown as the deadliest. And it's hard to argue against that title going to a specific ancient seaway that existed tens of millions of years ago in the most unlikely spot of all. And what's really strange is that as fate would

have it, its domain would one day give way to arguably the deadliest piece of land on earth as well. And this wasn't just some coincidence, as its creation as the deadliest waters, and then the rise of the deadliest land, were both ultimately tied to a single event. which put the world in a collision course with both, so to speak. It all began roughly 100 million years ago in North America, when at the time, the continent looked remarkably a lot like it does today, at least from space. But when you got down on the ground, you'd find that nothing was normal. And I'm not even talking about all the dinosaurs or terrors mocking about,

but rather the land itself, as it was undergoing immense chaotic changes, with two tectonic plates bashing into each other on the regular, causing frequent massive volcanic eruptions and creating vast mountain ranges. The volcanic activity alone likely upended life in the area and made things rather difficult. But it was really the changing the land itself that threw a wrench in the timeline, as while the two plates were colliding, they created a massive basin that ran vertically down much of North America. Now, typically basins always have an impact on the environment, yet this time around, things were a little bit different, as everything else about North America supercharged just how

terrifying it turned out to be. For starters, the continent was less elevated at the time. and the world in general was way hotter, resulting in water levels being higher than normal. These two points combined resulted in mainland North America eventually being invaded by water, which began in the north with the Arctic Ocean rushing down through the basin, where it eventually connected with the Gulf of Mexico, thus effectively slicing the continent in two and creating the western interior seaway, which in my opinion is the deadliest body of water the Earth has ever seen.

At its greatest extent, this seaway measured some 600 miles or 970 kilometers wide, and was over 2,000 miles or 3,200 kilometers long. And yet, it was remarkably shallow, only having a maximum depth of 2,500 feet or 760 meters. Now, yes, that's still uncomfortably deep as far as swimming goes, but for its measurements, it was basically as thin as paper. And to really drive this home, six lakes on Earth right now have it beat in the depth apartment, and the Mediterranean Sea has a max depth almost seven times greater, which thus makes you wonder, how could there be any sea monsters?

However, it was this extreme shallowness of the western interior seaway that largely resulted in an explosion of monsters, as it led to a large percent of it being shallow, warm, and sunlit, resulting in booming coral reefs and highly productive, epipelagic zones. Then, on top of it virtually being all tropical shallows, it also acted like a mega watershed, collecting runoff from both of the new island continents it created, Laramidia and Appalachia. This diluted the waters, but it also led to the water. to a lot of resources being dumped in, making the soup even more hardy for life, or so you could say. And this isn't even factoring in the gobsmacking amount of environments the seaway birthed.

As besides coasts, you now had the new addition of lagoons, wetlands, marshes, deltas, and more. All of this combined was like roids for life. And it didn't take long, until simply put, you could find every monster you wanted on demand in their final forms, and thus leading to its loving nickname, Hell's Aquarium. If that's any indication, for you. For starters, reptiles were largely represented by multiple giant mosasaurus, some of which were the largest of their kinds to ever live, and they were in many ways that had honchos of the seaway, and went after just about anything they could catch, thanks to their titanic skulls, jaws, and chunky teeth, which were perfectly designed for cutting

through massive bodies. The most famous, of course, was the Mosasaurus Hoffmani, but it wasn't actually the most common face, with that title going instead to the near-equally giant, Tylosaurus, as well as the smaller platycarpus and clydasties. However, because the COA was just so abundant, mosasaurus ended up being not the only apic predator you had to watch out for, as large hyper-predatory sharks also called the water's home, who often can measure 5 meters or 16 feet long, and in some genera could even outsize the biggest great whites ever recorded. And thanks to their teeth, speed, and sheer aggressiveness, it actually seems that in a few cases, these sharks ended up becoming much more troublesome for certain life than the mosasors were. So with giant mosasors and sharks to worry

about, this alone would be enough for most to get the picture not to take a dip here. And still, the list of killers remain long, as giant carnivorous fish were plentiful too, who weren't only quite ugly, but could also gulp down man-sized prey, whole, not caring about what you were as long as you fit down its throat. And then on top of that, you even had crackens, i.e. cephalpods, to worry about as well, as it was in this relatively small sea that the largest cephalpods to ever live emerged. The parapasosia, which weighed up to 1.5 tons. In other words, nearly three times heavier than the colossal squid, our biggest tentacled friend of today, which also makes this the largest invertebrate of all time. This being said, of course not everything that called

these waters home were necessarily giant hunters, as there were plenty of pleasosaurs around that preferred smaller fishes, as well giant sea turtles that weighed three tons, but were rather chill, enjoying smaller-sized fish and jellyfish. And then you also had a lot of animals that you could still expect to find in seas to this day, like obviously a diverse range of fish, other cephalopods, corals, algae, and so on. And as one might expect, it wasn't just aquatic creatures that got a piece of the pie. If the rich waters led to a mind-blowing amount of pterosaurs, and may have been directly behind the most successful one ever, at least from a number standpoint, the Tyrannidon, which we know of through over 1,200 different specimens. And each of them,

could be six meters or 20 feet long, so by no means small. And then on top of this, it was also thanks to the sea's creation that we got one of the largest crocodilians ever, Dinosukas, an eight-toned behemoth with a bite strong enough to obliterate bones, while also having absolutely overpowered armor, which covered nearly its entire body. And to make this an even scarier prospect, this crock did not necessarily live solely in the sea,

as it was found primarily along the seaway's coasts and adjoining waterways, giving you just one more reason to steer clear. And ultimately, no place was spared by the sea's influence, as even fully terrestrial animals got a power up from the seaway's formation, mainly since the division of the continent resulted in two brand-new islands, Laramidia and Appalachia, which both became very diverse with different ecosystems, and resulting in North American dinosaurs undergoing a lot of diversification. So much, in fact, that when the golden era of the seaway began, the land was climaxing too, so to speak, reaching levels of life unseen in ages.

and both islands ended up producing their very own unique animals. And if you were planning a time travel getaway to one of them, here are a few key differences you might want to know. The western island, Laramidia, had on average much larger dinosaurs, possessing numerous sauropods which were more rare in Appalachia, while seratops and acalasaurids were much more prevalent here as well. You could also expect to encounter far more snakes while walking around. And though lizards in general were less common,

the continent did have a pretty major insect problem, so make sure to bring bug spray. though to be honest, I doubt you'd notice it that much, as the biggest problem was the presence of relatively large Tyrannosaurs, of whom a few evolved massive skulls and bodies, outsizing anything found in Appalachia. Yet, with all this said, don't think the Eastern Island was some peaceful paradise. No, seri, because while larger Tyrannosaurus hadn't really taken root there, many smaller, yet still deadly ones, did, namely the dripsisords, who typically had longer, more versatile arms and claws. Plus, Appalachia had a Dramanosaur infestation too, as well as an increased number of large

Nodosaurs, hadrosaurs, lizards, and then get this, carcordontasors, or at least one unnamed kind. And then, in a twist, it was here that dinosaurs met their match, as Appalachia was eventually overran by crocodilians, and not just the dynosuchus, who was the most plentiful here, but also numerous other kinds of aquatic, semi-aquatic, and even terrestrial crocs. And for what it's worth, I'll also mention that for a short of, time in the early days, Aliceroidia, and even the Acrocanthosaurus, possibly called this place home. So clearly, while life inside the Western Interior Seaway was thriving, so was life on land. And it wouldn't be crazy to have called North America the most chaotic place on Earth, both in terms

of land and sea. But the Western Interior Seaway still had one final trick up its sleeve, as its presence had unknowingly laid the foundation for the most iconic dinosaurs of all time. While the sea had always kept animals on their toes by fluctuating in terms of sea level, things started to take a permanent turn some 70 million years ago, as the water started to recede and would basically never stop. Courtesy of the continental plates started to uplift, resulting the land rising higher and thus slowly draining the waters. While the sea receded, its disappearance, as well as the plate movements itself,

had large physical impacts and influenced the climate too, which potentially resulted in the fact that within a couple million years, only 20% of the dinosaurs from the seaway's glory days were left standing. Not to mention that many in the waters disappeared too, like Cretoxirina, Arcalon, and Dinosukas. So at first glance, this may all seem bad for life, and good for any potential time traveler looking to stay in one piece. However, as the saying goes, one man's, or dinosaurs, misfortune, is another's opportunity. And while we do not know exactly where the seaway stood by 68 million years ago, we do know that it was greatly reduced, and in doing so had created a very peculiar situation

as it opened up a huge amount of new land ripe for the taking and created fertile soil through the sediment it left behind. And it was in this very vacuum that the most infamous place on earth arose, which housed animals so legendary that of all the formations we know of, it has become the best known. And that is Hell Creek. Its domain stretched out across portions of present-day Montana, Wyoming, North Dakota, and South Dakota, which had all prior been completely submerged by the seaway.

And in its absence, the area had become a vast floodplain littered with swamps, forests, rivers, and lakes, which are all great for life. But something was still different about this place, as it was home to a lot of dinosaurs who were also record breakers, chief among them, possibly the largest predator to have ever walked the earth, the Tyrannosaurus wrecks. It was partially thanks to the seaway's reduction and fauna turnover that it became the sole large predator in North America, and was without a doubt the baddest predator on the entire planet at the time, and perhaps ever, at least on land, as it was built like an absolute

tank that can only be truly appreciated when comparing it to other giant carnivorous theropods. And for now, it tendibly remains the biggest of the mall, at least from a weight standpoint, with the largest known femur indicating a weight of possibly 12.5 tons, while average sizes were between 5.4 and 8 tons. And just for good measure, the biggest complete specimen, dubbed Scotty, also holds the title as the largest completed theropod specimen known thus far. And as the rule goes, with great size comes even greater jaws. And the T-Rex had a titanic head, which was larger than a grown human, and filled with giant, pointed, and slightly serrated teeth, that can be pretty much summarized as lethal bananas.

And were absolutely overpowered thanks to massive muscles, which let it bite down with over 60,000 newtons of force. Which to put that into perspective, is three times greater than the current strongest bite force on Earth, and is strong enough to pulverize armor, muscle, and bone. And upon impact, it basically vaporized everything it touched, as evidenced by fossilized turds, which contained bones smashed so finely that they were like sand. On top of this, despite their appearance, the wrecks also had deceptively strong arms, that together could pick up weight close to half a ton, or pin struggling animals. And then to complete the package, besides having remarkable vision and smell, there's also a chance that this creature was social, possibly forming packs,

or at least congregating when blood was spilled. So, uh, not great. And in the end, this was pretty darn close to a perfect predator, and its size, plus bite, allowed it to hunt giant herbivores that were often absolute units themselves, being off the menu for the vast majority of other predators. So clearly, the Rex was one bad apple, and the last predator you'd want to run into, which is why Hell Creek was so deadly, as it was here that the king was the strongest, with a paleo study finding that it was the second most common dinosaur. And while it did live elsewhere in America, 85% of named specimens have come from this one place alone. So good luck trying to avoid one. And for the cherry on top, the T-Rex was quite rowdy, even when not hunting. As among specimens, many show signs of nasty fights, and in some cases bear evidence of cannibalism.

And honestly, the only saving grace was that due to its absurd robustness, the Rex wasn't exactly cheat-alike, and probably didn't bother much with smaller fleet-footed prey. But don't you worry, though, because while the type of the tiger was, that you worry, Tyrannosaurus was the sole giant killer, Hell Creek was home to a lot of little killers, too. Relatively little, that is. One of which may not have been so unrelated to it, the nanotyranus. A much faster and nimbler predator, but who was still uncomfortably big, hitting a maximum of 1.5 tons and likely hunting things more close to our size, if you get my drift.

Now, you may know that it's not really agreed upon what exactly this little nightmare was. As some say it was a juvenile T-Rex, while others think it was a unique genus. But frankly, I don't know if that really matters, because regardless of its true nature, it was still deadly, swift, and upended any potential peace for smaller animals. And then, in addition to many tyrants, you also had to reconcile with the fact that Hell Creek was a haven for raptors. Ironically, the one that we associate most with the T-Rex, the Velociraptor, was not present in Hell Creek, as they didn't even live in North America, but instead we had other raptors,

which were honestly much more scary, with the most common one being, the Akero who did actually happen to be very closely related to the Velociraptor, but was slightly larger, measuring up to three meters or ten feet long and weighing the same as big Bernese mountain dogs. Like others of its kind, it was armed with lethal sickle claws and a light built, granting it both speed, agility, and deadliness. And what's more is that like the king, this guy had a nasty bite, just for very different reasons, seeing that its serrated teeth were backed by a relatively weak jaw, resulting in applying weaker, yet rapid bites the slash, cut, and incur blood loss in prey. And, uh, let's just say this seemed to do the trick, as it ended up being one of the eight most

common dinosaurs in the area. And then on top of this, while rarer, you also had to worry about a much greater nuisance, but still of the same category, the Dakota Raptor. This fellow dromaeosaur was built a bit like the Akarra Raptor, having light springy bones. The thing is, though, is that it was absolutely massive for a raptor. Measuring up to six meters were 19.7 feet and weighing a bit more than even a grizzly bear. And of course, when you supersized a raptor, you get supersized claws too, with its being as long as a large chef's knife. So, about nine inches from top to bottom, allowing it to pierce extremely deep into prey, puncturing, and destroying vital organs. And what's more is that its flexor tubercle, the part responsible for wielding the claw, was built in a way

which indicated that it may have had the greatest slashing power of any germaosaur. The only good news here for herbivores and time travelers is that recently there has been a debate on if this predator had even existed as some painted to be chimeric in other words the bones that make it up may have come from more than one animal but regardless this still means these bones came from something and the other raptors sure seem to have their own fair share of scandals too as while another one the sarnith hell lestes definitely existed no one is certain if it survived long enough to see hell creak or had died earlier And hopefully it's the latter, because frankly, the area did not need any more predators, because among the ones that did exist, there was already plenty enough carnage.

And yet, you do not become the scariest land on earth with just deadly carnivores. You also need equally intimidating herbivores, which is what you definitely got in Hell Creek, and I mean that to the fullest extent, as literally the average dough in the area was the triceratops, one of the largest seratops, if not the largest, to have ever lived. To get a good idea of what this beast was like, imagine an average. African elephant, but more robust, meaner, and equipped with two pointed horns and a massive shielded head. Now you have some semblance of what you're dealing with, and most predators can only dream of taking one of these guys down, with the larger ones sometimes weighing 10 tons.

And even for the king himself, the T-Rex, they were no joke. With each of their two enlarged horns measuring over three feet or one meter long, and the T-Sarotops is actually the only dinosaur direct evidence of having injured a T-Rex. And even amongst themselves, their brutal was shown as 14% of all specimens had damaged to their heads reflecting intraspecific competition. Additionally, it was also joined by the nearly equal giant Taurosaurus, which just added that much more spiky horns to the neighborhood. Now, any formation would be iconic or having just one of the largest serotopsids ever. But being big was simply the norm here. I mean, just as to antacalosaurus, the heaviest ankyllosaurid ever discovered. This biological tank was armed, or rather armored, to the teeth,

possessing bony osteoderms that were wider than dinner plates and covered most of its upper body, providing immense defense and heft. And while it was quite a bit smaller than the T-Rex or T-Rex or Triceratops in both length and height, it still gave them a run for their money and weight, with the largest clocking in at eight tons. And it just so happens that it was also joined by other very armored and robust anchylosaurs, such as the Denver Saurus. But what really made the anchylosor so special and an absolute menace was its tail, or rather what lay at the end of it, as it had, two monstrous osteoderms that formed a hulking club that was then powered by flexible yet strong muscles that resulted in it being swung with greater forces than 370 professional baseball players

swinging a bat combined and based off of more recent studies it possibly goes up to a thousand players combined so uh enough to shatter even a teorex's leg upon impact and while not set in stone it is one of the few large animals from hell creek that's yet to be found with any damage tied to predators meaning it was such a beast that even the biggest theropods in existence left it alone. And even the stereotypical dinosaur punching bag of the land, i.e. hadrosaurs, would have been in most cases an untouchable unit, as here we had the Edmontosaurus. This hadrosaur was among the biggest to ever grace the earth. And most forget that once in a blue moon, specimens indicate that exceptional individuals could grow to be 13 meters or 43 feet long, and most likely weighed more than most

hyrxes that it lived with. And sure, it didn't have any clear visible weapons, but as far as titans go, it had speed, surprisingly powerful legs, and a robust tail. So think of a megacized bull just without the horns, and then throw in some deadlier kicks and a huge tail as well. So suffice to say, it probably wasn't easy pickings, despite how hadresors are often depicted. And that's even before factoring in their tendency to stick to large herds, the scale of which would make anything today look absolutely laughable. So between all these giants, you pretty much had to be a Titan amongst Titans to even fathom getting by here. And lower to the floor, smaller predators still had their work cut out for them.

Because remember that trend about them being big? Well, it extended to others too. For example, one of the four Pachycephalosaurs, known in Hell Creek, was the largest of its entire clade, being close to half a ton, and had a built-in battering ram that it was very generous with using, showcased by multiple specimens found with cranial dents and cracks. There was also a good amount of unusually big overraptors and ornithymosaurs, too, who often go forgotten about, but were quite diverse. The most notable among them being the Stryothiomimus and Anzu, who interestingly enough were not predators, but rather herbivores or omnivores,

with both being heftier than your typical human, but considerably faster. And in the case of the Stryothiomimus, reconstructions have given it a top speed of 80 kilometers or 49.7 miles per hour, so almost twice as fast as Usain Bolt's top running speed. And ultimately, even birds seem to have gotten a bit of that good seaway stuff. As one of the largest avian dinosaurs, we have, of the time, Magnus Avis, lived in Hell Creek, with this name literally meaning big bird, but not that big bird. So dinosaurs truly had Hell Creek on lock. However, as resource-heavy as Hell Creek, non-dinosaurs will no doubt spring up too,

and a wide variety of interesting ones came to make the land their home. I mean, we may even have to thank it for Boids overall, as the earliest known one was actually found in this formation. Meanwhile, various crocodilians peruse the waters, making any drink a, uh, excited. task, and then on land you had carnivorous lizards, which reached sizes seldomly seen before. In one genus was the Paleo-Sanawa, which can only be summed up as a Komodo dragon looking like carnivore, but it was in reality much more related to the Gila monster and possessed literal shark-like teeth which helped its shred prey apart. And still, I'd rather have dealt with it

than the true dragon of Hell Creek, the Inferno dragon, or literally dragon from hell. Now in reality, this was not a Game of Thrones dragon, but rather a giant pterosaur, specifically and as darked, that for a long time was actually thought to be Quetzelcoatlus, but is now recognized as a distinct genus, and in life it had a wingspan of about 4.2 meters or 14 feet, which is giant for a terrosaur, or really anything for that matter. And yet its true strength was not from its wingspan, but rather from its height. You see, while standing on its knuckles, it would have been able to easily peer straight over your head, and was equipped with its own Titanic Noggin that sported a pointy, sharp, long beak. And opposed to most terrorsors who normally hunt fish,

It's hypothesized that this guy prefer to stock the lands on foot, using its large beak to swallow prey whole or pick them apart. And it's generally considered to be a mesopreditor, meaning if you were a small juvenile dinosaur, squamate, or mammal, you were in for a whole world of hurt. So really, the only thing I can say about this is that it seems like wherever you were, Hell Creek had you covered with nightmarish animals.

But perhaps the cream of the crop is something which may confuse you because it is a Mosasaur, the Hell Creek Mosasaur. Now, this may seem odd, as I said, Hell Creek wasn't a seaway. And yet, in 2021, researchers found a Mosasaur specimen here, and a monstrous one at that, with most estimating it to be 11 meters or 36 feet long, with a few even more liberal estimates, giving it numbers as high as 15 meters or 49 feet, which if was the case, meant you'd have needed a bigger boat. And some have even tentatively called it to Mosasaurus Hoffmani.

But for now, at least officially, it remains indeterminate. But at this size, it's hard to see how anything was off the menu. And even an unlucky T-Rex who ventured too close to the water might have become a snack. But the bigger and more perplexing question is what it was doing in Hell Creek. For a long time, researchers knew that the environment had a lot of aquatic creatures, like fish and a bunch of turtles. Yet these were mainly found in fresh or brackish waters, and in far more inland locations than where you'd expect to find a full-fledged moses sort of be. So this has led to some differing hypotheses, none of which are currently verified. The most extreme of which is that this behemoth represented a population that learned to coast into brackish and sometimes even freshwater from the seaway further south.

And another proposed idea is that it was simply a lone individual that had accidentally found itself far more inland than it should have been. After all, while not the seaway, Hell Creek was still connected to it through its water systems. But none of these ideas are turning out to be very strong, and some have completely gotten rid of the notion that it died in brackish or fresh water. With another more supported hypothesis being that the sea is a sea is a very strong. The way's demise wasn't as straightforward as originally thought, meaning that you had some episodes where waters would rise again, giving Hell Creek some pretty interesting coasts. But whatever the case, I think the point remains that Hell Creek definitely earned its infamy, which thus leaves us with a final question, and that is, how do you fix a place

where virtually every animal has become legendary enough to obtain icon status? Well, it turns out that you give it a good old factor to reset by lobbing a giant space rock at it. Thanks for watching, and until next time. Ambition comes in all shapes and sizes. At First Citizens Bank, we roll with your goals because we're built for what you're building. Fit for your ambition for Citizens Bank. Yamava Resort and Casino at San Manuel is California's number one entertainment destination for today's superstars. Catch the Jonas Brothers return to the Yamava theater stage on April 30th, the powerful vocals of Demi Lovato on May 17th, and the signature Southern Country Rock of Eric Church on July 19th.

Tickets on sale now at Yamava Theater.com, only at Yamava Resort and Casino, celebrating its 40th anniversary. UN must be 21 to enter. Honest things too.