ExtinctZoo - Japan Once Had Real Kaiju

Episode Date: April 5, 2025

Today Japan is known for anime, good food, and everything kawaii, but once upon a time not only was it not kawaii, it was also one of the worst places you could find yourself on the entire planet, as it seemed to be collecting nightmarish animals like Pokémon.

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since 1954. And as you've probably noticed by now, Godzilla bears some resemblance to dinosaurs, and that isn't coincidental, with it actually having taken inspiration from not only the Tyrannosaurus, but also the Stegosaurus and the iguanodon, which is rather ironic, considering that none of these dinosaurs ever stepped foot in Japan, as far as we know. But there were others that made it to Japan, And during the Cretaceous period, it was actually quite the dinosaurs' paradise, or rather a nightmare for anyone trying to stay in one piece, as these dinosaurs were by no means kawai. And what was really strange about it all was that Japan was home to a bunch of dinosaurs you'd never expect to find together in one place, making for some pretty strange pairings. And let's just say, there were a lot of these bizarre matchups, and it almost seems like Japan was collecting dinosaurs like Pokemon, leading to the question of how, seeing that today Japan is a rather isolated country. with most of its land being about 124 miles or 200 kilometers away from mainland Asia.

However, a long time ago, it wasn't so isolated, and wasn't even an island, instead being stuck snugly to China, at least for some of the time, as Japan has taken on some odd shapes during its existence, and depending on the sea level plus tectonic activity, it was at times, an archipelago, a strip of land, and even a peninsula. But whatever the case, it sure seemed to have been a bountiful area, as life could be found in mass in every nook and cranny. And along with having an expansive shoreline, the heightened volcanic activity may have been what gave Japan such fertile grounds back in the day.

And even today, the country remains quite volcanic, courtesy of the ring of fire. But besides this, the similarities between past and present end. And this extends to weather, too, as back then, Japan had a much more chaotic climate that seemed to switch back and forth between cold and dry and warm and humid. This difference would have easily been felt

in the air, and was also reflected by the forests, which at the time didn't have as many of the iconic Sakura trees, but instead, cycads, cypresses, fruit-bearing trees, and ferns. The inhabitants were also, of course, quite different. And while life was abundant throughout the Cretaceous, fossil formations showed that it was really during the early Cretaceous that life popped off. And it seems that dinosaurs of nearly every kind wanted a piece to the land of the rising sun, with a diversity being frankly mind-boggling, and some of the residents included kinds you would definitely not expect to find in Japan, of all places, including what was potentially the

largest predator in the country at the time, the Spinosaur. When you hear this, you probably first think of the Spinosaurus, who resided in Africa, or maybe the Berionics, which was found in Europe. And yet, Spinosaurids did find their way into Asia as well. It might have even first evolved there, go figure. But they weren't widespread in the continent, and definitely was rather an anomaly within Japan. As so far, the only evidence we have of their presence is two sets of teeth. Now, you'd be right to question how you'd get to assume an entire spino from teeth alone.

But actually, spinosaur teeth are extremely distinctive and possess multiple atopomorphies, which is basically traits that are only found in one taxon. Therefore, we know for sure it was a spinosaur, and likely a medium to large one at that, considering that the teeth were comparable to the barionics in size. And estimates suggest that the Japanese spino may have been hypothetically between 7.5 and 10 meters or 25 and 33 feet long, and possibly over two tons at a maximum, which is more than four times heavier than your typical male polar bear. Though I will say keep in mind that telling size purely from teeth is rather hard. And while barionics was maybe its twin in size, its teeth

were overall much more like that of cyamosaurus, a fellow Asian spinosaur to which paleontologists think it shared a very similar lifestyle with, which let's just say is terrible news for all, a cyamosaurus was deceptively bloodthirsty. Certain adaptations like conical teeth and a crock-like snout pointed to a life spent near or in water for long periods, where a fish would have been its main prey, and isotopic analysis backs this. However, the cyamosaurus has also been associated with saropods. Specifically, paleontologists found sarapod remains on their teeth, which is pretty strong evidence that I at least indulge in a saropod every once in a while. Now, it is possible that this was just some scavenging event, but their frequencies to a point where some

suggest active predation. And while its teeth were not enough to do anything, it definitely could have used as large sharp claws to inflict serious damage, raking massive amounts of flesh off, or piercing deep into vulnerable areas. And while we do know from other spinosaurids that fish were numero uno, dinosaurs and terrosaurs were occasionally eaten too. Because of this, researchers think that our mysterious spinosaurid was actually an apex predator given its size. holding domain over any water sources like lakes, rivers, and streams, as well as the surrounding lands. And in a sense, the scenario is quite likely, as it was even bigger than the Siamosaurus while the Sauropods it lived with were smaller, with the two main ones having been the Fukui

Titan and Tama Titanus. Both of these Sauropods had a strong preference for Lower Japan, and they were also both members of the Titanosaur family, which are notable for their large sizes. Yet despite this, in the fact that each had Titan in their name, they were quite small for their family, with some estimates painting them as no more than 10 meters or 33 feet, so that makes them shorter than a T-Rex, which is by no means small, but these were soropods we're talking about. And in the weight department, they didn't do much better, hovering around a maximum of 5 tons.

Now I will mention there's a chance that Fukui Titan was a bit bigger, at possibly 16 meters or 52 feet. But ultimately, these were not supersized sauropods. which was bad news for Littlefoot, and juveniles in particular would have had a rough time, especially considering that Japan had a stupid amount of predators. And some weren't what you'd expect to see alongside a Spino. Or maybe you would if you had watched Jurassic Park growing up, because I am talking about a Tyrannosaur.

Now, before we get ahead of ourselves, I should clarify that it wasn't really a member of the Tyrannosaurida family, but instead a member of the Tyrannosauroidia superfamily, and thus making it a primitive ancestor or cousin to the T-Rex. For now, this tyrannosauroid has gone unnamed just like the Spino, and we only know it by its teeth, seeing a trend. But unlike the Spino, this guy was definitely specialized in taking out dinosaurs all the time, having teeth designed to puncture, crush, and cut into big-bodied prey like sauropods, hadosaurs, and so on. And let's just say in a fight between it and the Spino, I know who I'd put my money on, especially when considering that this Tyrannosauroid was also unusually large for a basal member.

In fact, its teeth were big enough that paleontologists had to rethink the whole timeline of when the Rex's ancestors started to get big. And for now it's thought that the much later, Apalachiosaurus, was closest to it in stature, meaning a potentially 6.5 meter or 21-foot-long tyrannosauroid roaming about, that also, given its primitiveness, may have had long, powerful arms and sharp claws, too, that made it just slightly more versatile. And it definitely seems like Cretaceous Japan had a soft, spot for predators with scary arms, because this was a three musketeer situation for large

theropods, being the spinosaur, tyranosauroid, and then to finish it off, the Fuku'i Raptoran, a type of mega-raptoran. This group, as you probably know by now, were all arms and claws, having giant four limbs that were equipped with two massive claws, which were recurved and razor-sharp. And the Fuku-I-Raptor was no exception to this. These weapons allowed it to both pin-pray and also shred them to pieces, while at the same time, being able to maneuver them like Plato, as they were hypermobile, allowing it to literally skewer and lift victims up to its mouth, where absolutely horrifying teeth awaited. Now all Megaraptorins had pretty nasty teeth, but there were levels to it, as they were

an extremely diverse bunch. And the Fuku-E Raptor happened to have just about the scariest, as its teeth was basically a hybrid, sharing traits typically seen in Carcorodontos swords and Tyrannosaurids, which are two groups explicitly known for having some messed up teeth. Carcrodontosaurids and took their trademark compression, with each tooth being very flat, serrated, and blade-like, while also sporting wrinkled enamels. Then from the Tyrannosaurus, it had oblique blood grooves near its serrations, and it goes without saying that anything called blood grooves cannot be good.

And it wasn't, as these were essentially etched out areas on the teeth that allowed blood to flow around them and out of a victim while biting down, essentially serving to speed up any blood loss. Additionally, the design helped the Fuku-E-Raptor bite like a madman as they prevented the teeth from suctioning and sticking into the prey, kind of like how an axe might get stuck in wood. And so without this problem, it was able to bite rapidly while causing major blood loss, which on top of its claws led to a swift death, or at least hopefully. What's more is that even for a megaraptor, this creature was quite quick-footed, being

light as a feather for its size, as the measured 5 meters or 16 feet, but only weighed 300 kilograms or 660 pounds, so less than the average seen in certain grizzly bear populations. And this lack of heft was due to its hollow and slender bones, which granted it abnormal speed, meaning that nothing was outrunning it. And that goes for any time travelers too, which is terrible news considering the way it killed. And what's worse is that the holotype, the biggest known specimen so far, was actually an immature individual. So in other words, it only got bigger. So between it and the two others, you can bet that herbivores were in for a rough time.

And this is not even taking to account that a potentially small to medium-sized Carcordanta sword also set up base there. However, thanks to the richness of Cretaceous Japan, herbivores still thrived, especially the hadrosaurus, which included the likes of the teeny koshisaurus, and then the big one, the Camusaurus, and then might have rivaled the Sarapods in size at its biggest. Yet it still wasn't big enough to remain out of harm's way, especially when young, and nor were the various iguanodontids that hadresors coexisted with. But perhaps size wasn't the key to staying safe here, and others did take alternative steps,

as best demonstrated by another animal that we also know from its teeth, but also tracks this time too, which both pointed to the fact that enchylosores were plentiful at the time as well. Now with just teeth and tracks to go off of, it's hard to say what kind of armor they were rocking, or if they had a tail club, but being surrounded by so many carnivores might have led to some additional pressure of developing quite a defense. defense. And it wasn't just ornithicians or sauropods who dealt with pesky predators. But other theropods, too, as Japan just kept pumping them out. And again, I'm telling you, there was something with a clause, as the two prominent kinds here were the therazenosaurs and Dinochiridae, two groups known for strange manicures. Now, they were all arguably very weird.

However, the ones in Japan broke rules typically seen, even in those families, at least in the case of the Japanese Dinochiridae, Tyrannomymus, meaning tyrantomimus. mimic. Unlike its most famous relative, the Dinochiris, this genus was not giant, instead being about the size of a human. But the real important difference is that while paleontologists think that the large claws of Dinochiris were mainly used to dig up and grab vegetation, in Tiranomimus, they might have played a more sinister purpose. You see, in many Dinochiridae, the claws are recurved, yet blunt. Meanwhile, in the Tyrannomymus, they were actually sharp, suggesting that they were used for predatory reasons on top of vegetation gathering.

An ostentician further backs this, as while they were adapted mainly for herbivorous diet, some of the teeth still had characteristics you'd expect to find in an omnivore, leading to the idea that it mainly ate plants, but would use its claws and teeth for an occasional meaty snack, such as invertebrates or small vertebrates. And while not as voracious, you can't forget about the therazenosaurs, who seemed to be even more plentiful, with paleontologists being aware of three different kinds, though only one is named, and actually didn't live during the early Cretaceous, while the other two have gotten undescribed, and are only known from fragmentary remains.

And because of this, we are unsure of just how big they were, and if they reached the giant sizes seen in the iconic Therazinosaurus. But based on the named small one, the parallel Therazenosaurus, we can't assume that they were likely on the smaller size. Now that being said, their claws were still quite big and nasty. I mean, after all, the family is known for having the longest claws ever seen in any group of animals. And in their case, paleontologists reckon that they were mainly used to do.

or hook and pull flora. And while not confirmed, it's likely that they were also used for mating displays, intimidation, and what seems to be obvious, self-defense. But this is actually still a debate of topic. Reason being that some argue that their claws were too flimsy to do any meaningful damage due to their brittleness. And then others say that while they could be used, they could not be used to slash, and instead were only good as stabby weapons, with one study finding that the claws showed maximum strain resistance during stabbing motions. So who knows?

Maybe the Megarovtorans had some competition. And actually, there was one more therazenosaur that I did not include in the counting initially, mainly because we weren't certain that it was one. And if you ran into it, you'd likely first think that it was some sort of Dramasaur. So, without further ado, let me introduce you to the Fukuwevenator. A dog-sized dinosaur, who is of 2021, is apparently not only a therazenosaur, but actually the very first one. From the outside, it looked more like raptors, with the similarities to Dramasaurus,

being chalked up to convergent evolution, though its claws did take more after its later relatives. But it was still an anomaly, having what I call a non-friendly build, as meat was still on this primitive creature's menu. And along with sharper claws than most, you noticed that it had pointed and recurved teeth, too. But if we take a good look at them, we'll see that it was actually already on the way to its pacifistic lifestyle, as some of its teeth lacked serrations and flattened out at the ends, while others were completely spatula-shaped, which in addition to a long neck implied a diet made up of large amounts of plant matter, with small vertebrates and insects sprinkled in. And for those little critters, their woes did not end with the Fukuwevenator,

as Japan had a plentiful amount to small ninjas too, or so you could say, which included the true daunted hypnovenator, the avi-a-lien dinosaur, Fuku-Epturics, and a not-so-little undescribed ramasaur, who might have actually been the same size as Jurassic Park Velociraptors. So in other words, you better bet some larger animals would have been on the menu as well. And all of these theropods seemed to show a heavy preference for dense forests that were situated inland, while also frequenting freshwater sources like rivers. And while many non-dinosaurs made up their prey, these smaller predators were likely advocates of feasting on the albalephosaurus and Scya Magnumus as well.

Too bizarre yet oddly cute ornithicians that were abundant in Japan. And to me, our strong cases for why we should definitely bring back dinosaurs, at least some of them. So clearly, early Cretaceous Japan had a dinosaur infestation. But in reality, it was actually more of an infestation of life, not necessarily dinosaurs, as virtually every group was thriving here. And you'd be hard-pressed to find an area where something wasn't on the floor, stuck to a tree, or swimming in the water. And this included a bunch of freshwater and land-based turtles,

dozens of species of frogs and toads, and many, many bugs. And in reality, if you're not a fan of insects, arachnids, and other small invertebrates, then Cretaceous Japan was not the place for you, and that's putting it mildly. Some regions, mainly swamps, were so bad that they basically rivaled the Carboniferous, and the quote-unquote creepy vertebrate lineup was no less intense. For starters, you had the classics, like lizards and snakes, which ranged in size and diet. And then you also had lizards that looked like snakes,

aka legless lizards, which weren't dangerous, but could definitely give someone quite the jump. Next, you had the more exotic and now extinct creatures, which made the swamps a bit more questionable. Chief among them were a few kinds of Christodieries, that varied quite a bit in size and niche. With skull materials showing that some had snouts very much similar to gharials, suggesting a fish-heavy diet, and others possessing shorter and more robust jaws, like those seen in alligators, which would have implied a more broad and hostile diet to human-sized animals. And while these guys looked a lot like crocs, that was all thanks to convergent evolution. And a couple of them might have lived quite a bit differently too,

because despite most being semi-aquatic, these guys in a few cases could become fully aquatic, spending essentially their entire lives in water. And though they weren't crocs, you did actually have real crocs too, or rather crocodilians. Namely, the Goniofolididae, an extinct family of moderate-sized bodied neosukians, with extensive armor both in their backs and stomachs, making them pretty darn tanky. And to go along with their defense, they also had a mean old mouth that could deliver crushing bites to basically anything that fit. Additionally, they were probably ambushed predators who lied in wait for anything to wander too close to the water's edge. And though not nearly as deadly or large, other creepish animals that called the swamps home included the Caganayas, Monjuro-sukas, Chokawa, and various extinct salamanders.

And of course, in swamps and freshwater areas, there are plenty of fish too. But surprisingly, none of them seemed to be that large or predatorial. But they did, however, attract an absolute plethora of terrosaurs, with the three major groups being tenor casmatidae, Sungarepturidae, and Ornithokiridae. Again, like the fish, these terrors were not necessarily all that lethal towards large animals. But their appearances could sometimes be a bit off-putting, and they, along with an alarming amount of dinosaurs running rampant,

might make you feel rather compelled to panic and try to flee the land, perhaps towards the sea. I mean, after all, there are no dinosaurs there. And this would actually not be the worst possible option, as breaking a bit from the trend, early Cretaceous Japan had some pretty chill waters, relatively speaking. At the time, the watery king was probably some kind of pliosaur, given their abundance worldwide. And you could also likely expect to find a handful of plesosaurs, ecteosaurs, and sharks. But I will say that all of them seemed to be rather rare in those days, which is likely due to one of Earth's forgotten extinction events, the Aptian extinction.

Ironically, while volcanic eruptions, they have been the source of Japan's diversity of life on land due to the fertile soils it created, it was actually also volcanic eruptions that wreaked havoc in the waters and caused this extinction event. Except this wasn't caused by the Japanese volcanoes, but rather the Rajmahal traps in India. Marine life everywhere was impacted by this event, and even the land got a bit scorched too, as it's thought that mammals last surviving relatives, the triteelodonts, got erased during this event, as well as unfortunately the very last Degosaur, which is likely why none were known in Japan at the time. And so overall, because of the fact that this had a marine life, groups like the Pleasiosaurus and Ecteosaurs were in very bad straits,

which led to the watered Japan being relatively peaceful. But I'd be careful to not let this get to your head, because the waters would not remain swimmable forever. And within a few million years, they'd go from chill to a complete poop show that made the land seem tame. This switch up essentially occurred of the early Cretaceous developed into the late one and it was marked by Pacific Ocean that was much warmer and higher than today

with waters being over 100 meters more elevated and also resulting in the ocean constituting 10% more of the Earth's total water than it does now which also means a lot more space for nightmares and perhaps thanks to the extinction event it was no longer the pliosaurs who were the main problems but instead mosasors who were also new to the world and let's just say they didn't waste any time

taking over Japan's waters, and within a short period, there were suddenly lots of them. In fact, not only did Japan have an abnormal amount, but they also seemed to be much more assertive here than in other places. As non-mosisor predators were fairly rare, which also makes this about one of the only times where no sharks was actually a bad thing. Of the bunch, the most troublesome and widespread was the infamous mosasaurus, who, while being best known for inhabiting the western interior seaway, was doing just fine here too. though the Japanese species was not the Hoffmani, but instead the relatively unknown Obetsuensis,

which was still one of the largest members of the entire order, measuring up to 12 meters or 40 feet long, and thus ensuring its apex predator status. Just like its relatives, it had powerful jaws adorned with numerous, large, and robust teeth, that were well designed for cutting through large amounts of flesh, so virtually anything was on the menu. And based on remains, this possibly included a variety of turtles, some of which could be quite, large, big fish, birds, other marine reptiles, and possibly even dinosaurs, as carcasses were known to float out to open waters every once in a while. Additionally, even other mosasores were probably snacks too, as the genus was highly aggressive, and attack marks have been

found on specific specimens. And so obviously, any large animals would probably want to stay well and far away from this predator. But the main issue was that it wasn't just megafauna that were on mosasaurus radar. As here, there were different genera specialized causing a different prey, making the waters safe for no one. For starters, you had the medium-sized Tanyosaurus, a Tylosaurus, that at its max was about 29 feet or 8.5 meters, give or take, and it was more specialized in slightly smaller animals than most ofosaurus, having weaker neck muscles but increased mobility that allowed it to hunt faster prey, as well as amazing binocular vision that led it better attract prey those

both agile and on the smaller side. But I say smaller, loosely. It also differed in habitat, preferring slightly deeper water. where it needed to worry less about getting gobbled up as well. Next, you had the phosphorosaurus, who preferred even deeper waters, and was smaller than both previously mentioned mosasaurus, with estimates ranging from 3 to 6 meters or 10 to 19 feet. And this creature was a bit of an oddball,

as unlike the vast majority of mosasaurus, its morphology suggested that it was a darn terrible swimmer, and thus leading to the hypothesis that had heavily relied on ambushes, utilizing the darkness of deep waters to sneak up on prey. And to aid in this bottom-dwelling life, Phosphorusaurus also possessed very large eyes compared to the rest of its family. And then to top it all off, it had slender jaws and many small teeth to help it catch squid and bioluminescent fish, giving it a kind of similar niche to lanternfish, who still live in the

area to this day. And lastly, there was the Megup Tarigius, a great wide-sized mosasaur who is essentially the cheetah of the waters. I say this because besides its nimbler stature, it also had a body plan which featured giant wing-shaped flippers, and the joints attached to them were hyper-mobile, resulting in being able to do crazy maneuvers at high speed, such as braking, rapid pitch control, and crazy turns, which basically made it a biological fighter jet, or rather submarine. So even the most agile prey wouldn't have been safe, which is thought to have been mainly

fish, and unsurprisingly, in these prehistoric waters, fish were very abundant, and it wasn't only mosasaurs that they attracted, but also flying things too, namely, terrosaurs once again. And the sushi must have been good eating this time around. Because these coastal terrosaurs were monsters, with the largest of the bunch, being surprised surprise to surprise and undescribed genera, which for now is referred to simply as the Taranodontid-like terrosaur, who had a wingspan of 6.8 meters or 22 feet. Which makes it not only the largest terrosaur ever found in Japan, but also in the entirety of Asia.

And it was further joined by probably the most infamous family of terosaurs out there, the Azdarkidae, specifically through the genus Neponopterus. This terrosaur lived in southern Japan, and like its relatives had a giant skull and relatively large body, boasting a wingspan of nearly 12 feet or 3.6 meters. However, given the proportions of asdarkids, it's almost guaranteed that while walking, it would have been even larger than the undescribed terasaur, likely standing taller than your shoulders. And though it lived in coastal areas, its design does suggest that terrestrial The other prey were a larger part of its diet than in most pterosaurs, as it had a proportionally giant neck and beak, though I will say it probably wouldn't have passed up on the opportunity

of fish if it presented itself. In joining the terrors in their love of Nemo were birds, like the Chupka Ornus, a flightless bird that specialized solely in fishing, having webbed feet that granted an impressive ability to dive down, with some remains even being found in areas associated with water depths of up to 80 meters or 260 feet. their presence here would have made it a requirement that they stay alert at all times, given the presence of not only mosasors, but also pliosaurs, which therefore means that for a brief period, Japan was one of the few areas, where you could see pliosors and mosasors compete against each other, and perhaps even fight, which would have definitely been quite the sight.

And if you think the danger ends here, you'd be mistaken as another new addition to the area where crackens, or rather giant cephalopods, namely the harbour toothis and yesotuthos. these guys only showed up some 80 or so million years ago. Thus, they probably didn't live with the pli-sores, but with mosesores they definitely did. And would have actually put up surprising defenses, considering that both were equal or greater in size than the colossal and giant squids, but also had more lethal beaks,

which seemed to be better adapted for hunting larger animals. What's more is that unlike our modern-day giants, that are quite shy, these two spend a lot of time in coastal waters, meaning that any swim would be questionable at best. and the chaotic nature of Japan and the waters seemed to remain until the very last days of the Cretaceous which then of course received the untimely KT extinction event

that ended up erasing most of the animals that made the lands quite questionable but hey at least now we have sushi and anime thanks for watching and until next time on a own it all pay off your home travel for life drive a Ferrari in celebration of the world premiere of the monopoly big board buck slot machine by aristocrat gaming

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