ExtinctZoo - When Thalassophobia Kept You Alive

Episode Date: January 25, 2025

When you go swimming in the ocean or seas, the last thing you want to swim into is a shark... but what happens when everything is a shark?

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Multi-vehicle discount, safe driver discount, uh, new vehicle discount, storage discount, legacy how many discounts will you stack up? Tap the banner or visit usaa.com slash auto discounts. Restrictions apply. If you walk up to your crush and point blank ask them, who are the top dogs in the oceans and seas? Best bet is they're going to say sharks. Yeah, we have things like orcas, barracudas, giant squids, etc. but most people still think the salty waters of earth are ran by jaws.

However, at the same time, in the grand scheme of life, sharks claim to be king is a relatively new one, as they only became prominent marine hunters following the end of the Mesozoic, which saw the extinction of the previous nightmares, like the Mosasaurus and Pleasiosaurus. What's strange, though, and unbeknownst the most, is that sharks actually already had their chance hundreds of millions of years ago before the Mesozoic,

and were actually doing better than they are now, representing in many ways their true forgotten golden age, as nearly everything swimming around back then was Jaws. And this was the Carboniferous Period. To arrive at this point in history, you would have had to travel back a mind-numbingly long time, as it played out between 358 and 298 million years ago. In other words, nearly 66 million years before the dinosaurs had even evolved.

Ironically, though, despite it having been the best times for sharks, these days it is better known for its variety of giant insects. insects, arthropods, and amphibians that lived within the vast coal swamps of the time, which stretched across the entirety ofangea. A bygone ancient supercontinent now, but a newborn baby back then, as it formed during the very early days of the Carboniferous, uniting the majority of Earth's land, and covering up to one-third of the entire world,

which, just in comparison, the largest continent of today, Asia, only scratches 8%. And this is impressive and all, but it's nothing compared to what was happening to the waters. because as the continents came ever closer to one another, it resulted in huge amounts of undisturbed ocean and leading to the creation of super oceans, which are unheard of today. The big one was the Panthalassic, which lay to the east and occupied over half of the Earth's total area, meaning that if you wanted to fly across it in a commercial jet, you'd have to pack fuel for a trip over 24 hours long. And its size was so monumental that it was pretty much the only freestanding body of water on the planet, as the other ocean, the paleotethysts, was in some ways contained by land and various islands,

but it was still very much big by current standards. And both oceans on vastness alone would give any sane person a very healthy dose of thalasophobia. However, our fear of water ultimately boils down to what's inside it, and during the carboniferous, nature seemed to be injecting oceans with some sort of potion turning everything into sharks. And if you went for a swim, you'd have a better chance of swimming into something that looks. like jaws, then not, as sharks were painfully everywhere. In fact, so far, paleontolodos have identified over 45 families from the Carboniferous period, while nowadays there's only a possible maximum of around 30, so an increase of nearly 35%. But this difference is only really crazy

when you take into account that oceans and seas back then were way more empty than they are today, as one study found that in the present, there are about 800 or so different marine families, while back then there was less than 500. Therefore, sharks nowadays count for less than 4% of all marine families, but during the Carboniferous, they made up over 10%. A better way to imagine how insane this is is that if you wanted to make today as shark-friendly as the Carboniferous was, you'd basically need to double the amount of sharks swimming around,

which, if you ask me, is way too much. What's more odd about this whole thing is that nothing else in the water was really popping off like sharks, but on land there were multiple groups that were doing strangely well, including those giant bugs and arthropods that tickle another fear in our brains. And yet the coinciding time of giant creepy crawlies and shark NATO was in the end a coincidence, as the former are believed to have arisen thanks to an increase in atmospheric oxygen,

while the success of sharks is thought to have come from a completely different thing, which was essentially luck. Just like many animals had done before them and would do after, it turns out that they had essentially won nature's equivalent of the lottery, having survived a mass extinction with relatively little damage. In this event that I'm referring to is the late Devonian die-off, the second of the Big Five, which killed roughly 50% of all genera at the time. Thoughts on what caused this event ranged from severe volcanism

all the way to the expansion of plants. But whatever the case, the oceans were especially rattled, and many of the top apex predators were completely wiped out, including the placoderms who had ruled supreme and nearly all of the sea scorpions, and thus opening the door wide open for sharks, who wasted no time. And they were actually already pretty ancient at this point, having evolved 90 million years prior, but you could say that they were never really the popular kids. But this time things would be different,

with a number of species ballooning by 350% in very little time, and turning the world into an absolute shark fest. This included entirely new groups and new and improved versions of already existing ones. Many became bigger than ever before, making sharks the largest animals swimming around, while others pushed the limits on biological weirdness. But one fresh-faced group that beautifully combined the two of these was the Eugenio Dantida, the now extinct order that first appeared during the Serpicovian stage. Scientists have identified 32 different genera belonging to this group,

and they were largely united by two things. one, pectoral fins that were supported by long radials, and more notably, tooth warls, which were usually razor-sharp serrated teeth embedded into a spiral root, which made them look pretty metal. These odd dental structures came in many shapes and forms, but typically they had a strange resemblance to man-made saws, with some bearing mouths similar to chainsaws, while others had what seemed to be built-in buzz saws. These bizarre contraptions ultimately proved extremely versatile, and the Eugenio-dontids, rapidly became the dominant hunters during the Carboniferous, being found in both deep and shallow waters, where a few also became the giants of their time.

Most notable among the behemoths was the Adestis, which is lovingly nicknamed the Cisertooth Shark, and it inhabited the UK, Russia, and the United States, where it routinely grew to lengths greater than 6.7 meters or 22 feet, so about the same size as the biggest known Great Whites. Because of this stature, its two thwarts were absolute giant, with each one being about the length of your arm, and leading to great interest on how they were actually used. For a long time, the popular thought was that, like its nickname suggests, Edestis would operate its mouth in a scissor-like fashion, using cutting motions to chop and dice up on lucky prey. With some reconstructions finding that each snip generated 1,900 newtons of force,

three times the power of a wolf bite. However, recently a new hypothesis paints an equally grim but different picture, where instead of moving its mouth, Edestis and its kin would instead move its body up and down in order to generate sawing motions, and essentially thrashing prey into pieces. And so both of these options, either being snipped or sawed into pieces, are not very fun. And recently, the list of potential victims have grown as well. Paleontologists used to think that it solely ate jellyfish or maybe shelled animals, but now we think it was more versatile, preying on the previously believed animals,

as well as fish and other sharks. And it wasn't the only one doing this, as Adestis was a part of the specific Eugenio-daunted family, Adestaday, which included close relatives like Helicampetus, Lestridus, Euktenius, and Protoporata, who all had similar dentition yet differed in size, with its relatives being more comparable to reef sharks than large-grade whites. They were no doubt an odd bunch, but they really weren't the weirdest carboniferous sharks, with a better candidate being another Eugenio-dontative family, the Helicoprionidae. This name may sound familiar, for it was coined after the Helicoprion,

a large shark who had a circular saw for a bottom mouth, while its top jaw were all gums, a common theme amongst this family. However, despite being relayed to Adestis and other Carboniferous Eugenio-Donts, this behemoth wasn't actually a part of the Golden Age of Sharks, living further down the line during the Permian, with instead the Carboniferous genera from this family, consisting of the Agassizitis, toxoprion, and Arpagodus, all of who are sadly poorly understood, and are not conclusively thought to be anywhere near the size of Helicoprian.

Don't you worry, though, because there was one more member that I haven't mentioned, that wasn't just bigger than the Helicoprian and Adestis, but is also the largest animal we know of to have ever lived up until the Carboniferous, the Campelopreon. Superficially, it probably looked a lot like any of its close relatives, but if you swam up to it, there was no mistaking it. For the Camp Lo Prion was massive compared to its co-existing kin, with the largest known teeth suggesting a length of 9 meters or 30 feet. So basically on par with whale sharks from a length perspective.

To avoid such a monster, you'd have wanted to steer clear from water surrounding Russia and the US, where it was the undisputed apex predator, but who it terrorized is up to debate, Since like the Edustis, we haven't quite figured out how the Helicopriana day used their mouths. Originally, it was thought that they were designed to snag soft-bodied prey like squid and jellyfish, which were then ushered down their throats as they closed their mouths. Yet now, based on recent research, there are some new possibilities. One being, that they were actually specialized in shelled cephalopods. And certain models found that if their whorls contacted a hard-shelled animal head on,

then a deshelling effect would actually take place when it retracted its whorls, and thus removing the soft animal hiding within. Separately, another test that extrapolated bite forces of kin found that it might have bit with 2,300 newtons of force, while generating stresses greater than 50,000 pounds per square inch, which would imply that it was a lot more bloodthirsty than expected, as such power would allow it to cut straight through bony fish and sharks without even the need for top teeth.

And we know this design definitely did the trick, because not only did it remain present in Permian descendants, but it was also the route taken by two other main families that made up the Eugenio Dantida, those being the Cassio Dantoidea and Eugenio Dantidae, who opted for this same circular design over the type seen in Adestis, with the only major difference having been their smaller sizes. And instead of sharp serrated teeth, they bore round pavement-like dentition, which indicated a durophagous diet of crushing shrew. shelled and exoskeleton-bearing animals. They also made up for their lack of size with weirdness,

because the couple, like Ornitha Prion, evolved some pretty strange heads on top of their whorls, which included a comically elongated bottom lip, or rather rostrum, which jutted out like a spear, and may have been used to sift and prod the seafloor, unsticking bivalves, and other floor-dwelling prey. Like the others within this order,

these two families could be found worldwide, and as a whole, the Eugenio Dantida were the fernia. face for carbon infras sharks, having played major roles in many of Earth's marine systems. And yet, despite their occasional giant size and terrifying appearances, swimming into one of them wasn't always the worst thing, because when sharks are at their best, you're bound to get a couple of groups that are even more voracious, with one of these groups having been the tenacanthiforms. Superficially, they mimicked modern sharks more than the Eugenio daunteds did, but they were still a little bit off. For one, instead of having reduced second dorsal fins, theirs were large,

and in some cases even bigger than the first ones. This may have helped cut down on drag, though it could have also been a secondary adaptation to support another strange feature, built-in spines. While Eugenie O'Dontids wanted to be chainsaws, these guys wanted to be cactuses, as members had large spines that connected to the front of their dorsal fins, and due to their size, sharpness, and occasional thorns, it's likely that they were used as a deterrent against other predators, including themselves, as they could be quite feisty. Many of them lived in shallow waters where they would act as ambush predators, and held similar ecologies to the modern-day bullshark,

as well as falling within a similar body size range, with the most common one, the Draco Pristis, having an estimated length of two meters or 6.7 feet, while the rest nearly never made it past 2.4 meters or 8 feet, although at that size it's not exactly reassuring. The only silver lining here, for the time-traveling enthusiast, is that their diets were largely dictated by what could be swallowed whole or crushed, as they possessed multicusp teeth,

a bit like those seen in sand sharks, which were designed to penetrate prey and grip them tightly so they could then be swallowed, rather than for slicing and dicing their prey to shreds. Therefore, while a bite would still probably suck, especially since they had 12 rows of teeth, Megafauna most likely did not have to worry about getting gobbled whole. Yamava Resort and Casino at San Manuel is California's number one entertainment destination for today's superstars.

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Fit for your ambition for Citizens Bank. The safety, though, was not extended to deeper waters, as it was in the open ocean that the two largest Tenacanthiforms ever resided. The Glickmanus and Sivodes. These two were essentially the closest thing you had to grow. great whites at the time, in the sense that virtually everything at some point could fit in their mouths, as adults could grow to be 7 meters or 23 feet long, and weigh close to 3 tons. And exceptionally large individuals might have been even bigger, with a set of abnormally large teeth from a cybatist specimen indicating a length greater than 8.5 meters or 28 feet.

And despite the teeth not being designed for cutting, they were on average longer than those seen in great whites. So even if one just grabbed you with its mouth and then let go, it would still be kind of like getting stabbed by hundreds and hundreds of mini daggers. I mean, just imagine a sand tiger shark's mouth but over twice the size. It also didn't help that these two giants lived together at the exact same time and coexisted with a giant Helicopriande as well, leading to an abundance of Titanic sharks. It wasn't that being big was necessarily a trend,

but rather that since sharks were so numberful, there was bound to be a few who became massive. but no others approached this chonkiness to this great of a degree. Remarkably, though, they did get weirder, with the most perplexing having all come from the same order, the simile reforms. Families within this order were generally defined based off of specific internal anatomy,

meaning that some could appear quite normal in the outside, like Clato Salacaday. But others, not so much, with a couple developing some seriously messed up dorsal fins, with the chief perpetrator among them, having been the stethicantidae. I don't even have to explain what's wrong here, as their dorsal fins painfully resembled anvils more than actual fins. And you may be wondering, why on earth would anything swimming when such a

clunky structure strapped to its back? And this is a good question, as it likely caused a bunch of drag, rendering stethicanthids slow, cumbersome creatures that were most likely restricted to living on the seafloor, endlessly looking for even slower prey. To make matters worse, they also had giant patches of many spines on top of these fins and their heads as well, adding just more additional drag and making them wide open to attacks. So, why bother with these fins and spikes at all? Well, based on recovered specimens, paleontologists concluded that only males possess these strange structures, leading to the belief that these were used for mating displays. Amazingly enough, they somehow managed to be slowed down even more thanks to quill-like protuberances

attached their pectoral fins that stuck out backwards. And yet, in despite of it all, they managed to exist for 50 million years, and fossils have been found in the majority of continents, with only Antarctica, Africa, and South America lacking any. So, evidently, the fins worked. You also can't forget about the Falcaday either, a closer related family who had questionable dorsal fins as well, yet to a lesser degree as theirs were narrower and lighter,

allowing them to retain some degree of nimbleness. Of the four confirmed genera, the only one we have a fair understanding of is the Falcadus, a tiny shark who is shorter than a ruler, and who, like the Stethachanthids, only had its modified fins on males, leading to the same belief on its functionality. And in another act of solidarity, Falcadus and its relatives live deep underwater, too. But this wasn't out of necessity due to slow speed, but rather, due to the fact they had large goofy eyes that were specialized to pinches. point small prey zipping around in the dark depths of the ocean. And they were actually surprisingly

fast, thanks to proportionally large and long tails, which would have provided powerful locomotion. Interestingly enough, they and Stethicanthicathids were equipped with cusped conical teeth just like the tenacanthiforms were, which was maybe a good thing for those with philosophia. But you did have other sharks to bridge this gap. And actually, there was an entire order known for being the jack of all trades when it came to dentition, the hybridons. Swimming into one of them would be a hard thing to avoid, and would kind of be like playing Russian roulette, as each one had varying teeth that resulted in this group expanding into every kind of niche possible. And across the board, members are capable of crushing, tearing, grasping,

or cutting through their prey. They were further upgraded by having relatively robust bodies that allowed them to stage powerful strikes and emerge unharmed from intense battles. And while not humonging, Some were respectively big, measuring 3 meters or 9.8 feet long. And in spite of each having very different teeth and therefore different prey, there is a consensus that in general hybridants were slow swimmers and would use bursts of speeds to chase down their unsuspecting prey. And this group would only get stronger and stronger over time, enjoying more success during the Mesozoic than during the actual golden age of sharks.

However, there was one place where they were kicking butt, and it was somewhere that sharks had only managed to just infiltrate during this period. Fresh water. And what this means is that no matter what body of water you were in, there was a fair chance that a shark or two were just waiting within. And to make matters worse, back then, fresh water was comparatively way more shark-friendly than now. Hybitants were at the forefront of this conquest, and egg cases belonging to them have been found in many freshwater environments

and spread out across the entirety of pangea. and in greater numbers than what was seen in the ocean. The only saving grace here is that non-marine hybridants weren't that big, with the largest genus, the licidus, only growing to two feet or 0.6 meters. And now, that's the good news. The bad news is that there was one other order of sharks that made freshwater environments their home, and did the term river monsters better justice, the xenocanths.

Keeping up with the times, they were found everywhere, and were highly aggressive predators who are a lot bigger than our freshwater hybrids. With the most well-known genus, the xenocanthus, measuring 1.2 meters or 4 feet long. And that was one of the smaller ones. However, in this group, the tinier genera were given additional help. As similar to the tenacanth forms, genera sported large spines or spikes that might have doubled as defense mechanisms against larger xenocanths and giant fish, like the rhizodons.

And its pointy end was possibly much more problematic than you'd assume, as a few researchers speculate that they were venomous. And even if they weren't, stepping on one was guaranteed to suck, as some grew to be 15% of the total body length. Ironically enough, though, Xenicants lacking massive spines were the true ones to fear, perhaps because they didn't need them. Best exemplified by Labacacanthus, the apex predator of late Carboniferous rivers. This xenacanth made Xenacanthus look like a puppy, as matured individuals were able to reach 3.5 meters or 11 feet long, and had teeth accessorized with literal tines or prongs to impale prey, which were then devoured whole. And while a bit smaller, there was also the Orthocanthus, who clocked in at 3 meters or 10 feet, and had a more streamlined build, plus nasty V-shaped teeth that would have given anyone nightmares if it smiled.

They were also deadlier in some aspects, in the sense that fine serrations ran alongside the side of their teeth, resulting in bites having both the slicing effect and an impaling one, and allowing them to hunt smaller and large animals. Thanks to fossils, we also know that of all the xenocanths, the orthocanthus was the meanest, with specimens routinely being found with multiple spines inside their stomach cavities. In other words, these guys were serial cannibals that would not hesitate to take a bite out of their own. And this aggressiveness surely extended to all in their path. And just to make them even more creepy,

genera were also covered in abundance of modified fins that suggest that they could not swim like normal sharks, but instead had to operate in an eel-like fashion, undulating their way along rivers, just waiting for their next victim. In such an environment filled with sharks, one of the only animals guaranteed to be safe was, of course, another xenocanth, the Barb Clebornia,

a 5-meter or 15-foot-long unit that lived North America. This creature could kill by looks alone, yet it was in fact the gentlest of all xenocanths, having teeth so small that it's led paleontologists to believe that it was a filter feeder. This does also mean, though, that not even microscopic organisms were safe. In showing that no matter where you swam or what you were, there was a shark just waiting out there designed specifically for you. I mean, it was the golden age of sharks after all. And yet, there is a plot twist I need to get off my chest. Which is that none of these might have actually been sharks. I say might have, because while they are commonly referred to as sharks, by amateurs and institutions alike,

they weren't real modern sharks as we know them to be. It's kind of like how we think of crocodiles as having been around since the dinosaurs, yet real modern crocodiles only appeared 16 million years after they vanished. So what I mean is that it's simply that many of the animals I mentioned fall short of ticking off all the boxes that define true sharks. But the Carboniferous is still very much regarded as when shark diversity was at its peak. And from a holistic perspective, not even the giant insects, which the period is known for, were doing better, which lead to the question of just how is the bag fumbled? Well, two words. Double doomsday.

Just like how they came into power, it was Mother Nature that shut them down, temporarily. As in the late Carboniferous, Earth was struck by two extinctions. the Surpicovian extinction and the Carboniferous Rainforest collapse. Both of these were triggered by events which wreaked havoc on the climate and impacted sea levels, and leading to over 50% of all Marine genera dying out. And because sharks were everywhere and the biggest animals, they were unsurprisingly heavily impacted. And while they survived, they entered the Permian weaker than before,

but still impressively strong. Then, by unbelievable misfortune, they would find themselves dealing with three more deadly mass extinctions in under 21 million years, including the worst one of all time. And now this all combined was too much even for sharks. And when the Mesozoic arrived, they were back where they started. And now this could all be seen as very sad for sharks. But personally, I think it's a testament to how hardcore they are,

because even after surviving all of that, they still managed to reach Apex Predator status a few times during the Mesozoic. despite things like this, and eventually made their way back to the top. So really, what a comeback story. Thanks for watching, and until next time, on Extinct Zoo.