ExtinctZoo - The Fossils That Shouldn't Exist

Episode Date: October 4, 2025

Didn't have two headed marine reptiles and dinosaur mummies on your bingo card, did ya?

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then you're probably aware that fossilization is kind of a big deal, being pretty dang rare. In just in case, you need a quick refresher, it's thought that less than 1% of all deceased animals undergo this process. Therefore, it's not crazy to call any fossil, both rare and unique. However, like everything, there is of course levels to this. And this has made me think, what exactly are the rarest of the rarest fossils or paleo-fines that we've discovered thus far? And apparently, it's kind of hard to say, as I quickly came to realize that it's kind of impossible to say it shurdily, especially since what would constitute as the

rarest is pretty subjective. But, in my oh-so-arduous research, I did stumble upon a few discoveries that stuck out more than others, some of which I even legitimately thought were fake at first. And this included one image that upon first seeing, I mistook for a monster from Greek mythology, when really it was a scientific sketch. I mean, see for yourself. At first you might be thinking you're looking at a newborn hydra, or some sort of long-lost kaiju.

But this is in fact a real creature, and not of the alien kind either, but instead an earthly animal that lived long and long ago in a galaxy not so far away, the high phallosaurus, meaning the submerged lizard. They first appeared during the early Cretaceous period, and were, let's say, an odd bunch. not because they had two heads, as that fact is actual makes this specimen so rare, as this guy is polycephalic, meaning it had more than one thinker, and in this case also possessed two necks. This amazing find was made in 2006 by the UK Royal Society within China, and was so rare that the paleontologists first thought that it must have been two separate specimens,

and they were just missing a second body. However, the remains were well preserved enough that after it was fully analyzed, there was absolutely know mistaking that this was a double-headed reptile, making it also the oldest example of polycephaly, and the only known case where one is fossilized, making it literally one-of-a-kind. When the news of its discovery was first made, there was naturally quite a bit of buzz around it and some confusion, as was reported to be a two-headed dinosaur. But sadly though, for the sensationalists, hyphalosaurus was no terrible lizard, rather an aquatic member of the ancient Caristadera, and now extinct order of diapsids, which

are widespread for the mid-Masazoic all the way to the recent Cenozoic, and contained members such as the champsosaurus, who is well known for living alongside the T-Rex. And the group as a whole differed greatly in appearance in size, with the high phallosaurus specifically, superficially resembling a plesiosaur, albeit a miniature one at that, as this guy was fun-sized, with fully grown adults only reaching about three feet or one meter in length. So luckily, they get the safety approval stamp for time travelers. You also wouldn't have to worry about seeing this creature too often either, as they were extremely adapted for aquatic lives, being pretty much found exclusively within the deepest parts of lakes,

where they utilize webbed feet, a flattened tail, and needle-like teeth to hunt, with prey mainly consisting of tiny fish and soft-bodied invertebrates. Not super-duper exciting, but exceedingly effective, and the high phallosaurus has actually provided paleontologists with thousands of specimens, but of course only this one has come with two heads, which is for sure remarkable, but at the same time a little bit sad, as these These guys did not get a chance of life due to its birth defect. And we know this because the specimen's body size was extremely small even for this genus, leading to the assumption that it died early in infancy or was even already deceased at birth.

And this does kind of check out because we do know that polycephaly in general does tend to greatly reduce lifespan in the affected. And what's kind of interesting when you think about it is that this fossil is obviously reptilian, and one interesting tidbit is that in modern times polycephaly is often noted for being much more common in reptilian. compared to mammals, and specifically happens quite a bit in snakes and turtles, who are also both diapsids. Now, it's not exactly known why this happens, but it does lead to the fascinating notion that a two-headed dinosaur could also be out there as well, seeing that they too were diapsids. So definitely a rare find, and one with somewhat sad undertones. But let me tell

you, it doesn't hold the candle to the heartstrings pulled by another extremely rare fossil find, which shows just about the only known instance of two prehistoric animals cuddling, and to make things even crazier, the cuddlers aren't even the same species. This all started in 2013, when a team of paleontologists operating in the early triassic portion of the Karoo Basin, stumbled upon the fossilized remnants of a burrow. Now, an ancient burrow alone is pretty remarkable and rare in itself, but there was also something hidden inside, a Theronaxodon, a type of carnivorous synodont which has survived the pyramid extinction and was about the same size as a fox.

Specimens belonging to this species had been found in burrows before, and perhaps because of this, not much interest was initially paid to its presence, and the Thronexodon went unexamined for quite a long time. However, thanks to a bit of luck, the cast was eventually scanned at a facility in Europe, and they found something the first review missed, and that was an entire other creature in the burrow. And get this, it wasn't a Thronacodon, nor any other kind of synodont, for that matter, but instead an amphibian of all things,

Brumistega. It belonged to the Temptospondoli order, which first appeared during the early Triassic, and they were not known burrowers. So what on earth was the Brumis stega doing alongside its renaxidon in its den? And not just alongside, actually, but rather tightly pushed up together

like two peas in a pod. And at first we thought the answer was pretty easy, being that this was no cuddle sesh, but rather a predation attempt that was rudely interrupted. Yet, this hypothesis quickly fell apart, as neither animal were the others, typical prey, and none of their skeletons showed any signs of the two having fought.

Although, in their analysis, they did note that the amphibian was injured, having suffered several fractured ribs on the right side and two bite marks on the roof of the skull. But evidence suggests that these injuries occurred prior to it undering the burrow, and are now actually believed to have been the spark that ignited this odd situation to begin with, with the idea being that after being injured, paleontologists reckon that the Brumusaga, exhausted and now in pain, stumbled upon the den and decided to venture within, in the hopes of finding some shelter. It's also believed that it chose an underground area instead of something above because the early Triassic's intense heat and aridity. Within, the Brumistega encountered the

Thranacodon, who did one of either three things. First, it might have attempted to kick the new roommate out but couldn't manage, and thus had to simply put up with the unwelcome cuddles. Second, it could have just been a good dude and simply paid no attention to the amphibian, allowing it to share its home. And then the third and final option is that the Thronachydon might have been in a state of something called Aest of Aisivation, which would make it just be a good. makes sense given the area's extreme seasonal ridity. And for the uninitiated, ace divasion is basically a state much like hibernation, except for the heat and dryness instead of the cold.

And therefore while in it, the Throne Accadon wouldn't have bothered with trying to evict the Brumustega in the first place. But whatever the situation was, once inside, the two got cosied up with each other, as their positions showed the amphibian resting on the right side of the Thronacodon, with their bodies heavily pressed against each other. Unfortunately though, this adorable scene would ultimately conclude with tragedy. as the fact they were fossilized together, of course, means that they, well, died together. And the current hypothesis is that whilst resting, or napping, a massive flash flood

descended upon the area, thus flooding the burrow and slamming the pair into one of the corners, rapidly drowning them. Unpleasant to say the least, and very sad. Yet this being said, a fossil doesn't have to be sad in order to qualify as extremely rare. Sometimes it can just be itself, with the craziness stemming from who the fossil actually belonged to, and this is perhaps best seen into one of the rarest primate specimens of all time, and in fact, one of the rarest human specimens of all time. Back in 2012, Russian archaeologists were excavating the Denisovic cave, which is located

in the all-time mountains of Siberia. The location was well known for being the discovery site of the Denisovans, and these guys are an extinct species of humans which disappeared around 30,000 years ago, making them one of the most recent groups of humans to have lived. And during the excavation, researchers located a single fragment of a long bone that was then grouped with almost 2,000 other poorly fragmented bones, which were visually unremarkable. But eventually, some of these pieces of bone underwent further testing, including genetic testing.

And in the case of the long bone, peptide mass fingerprinting and mitochondrial DNA analysis were employed. And the results were a bit shocking to say the least. As this specimen, now dubbed Denny, turned out to be a human hybrid. Yeah, sometimes real life is stranger than fiction. And she wasn't just any regular old hybrid, but importantly, a first-generation one, meaning she was half and half of two different human species, and thus far, Denny is the only known specimen of a first-generation hominine hybrid, meaning across humans, chimps, and Bonobos, she is

the only known case. Furthermore, it turned out that this 90,000-year-old human wasn't even a mix of Homo sapien and something else, rather a split of two fully-gone species, Denny Sovins, which makes sense considering the cave and our favorite extinct relatives, or at least mine, the Neanderthals, with the testing showing that her mother had been a Neanderthal and her father and Denisovin. So suffice to say, this was a mind-blowing find and one that came with immense ramifications, as it led to speculation that interspecies mating between Denisovans and Neanderthals could have been ongoing over several periods of contact that lasted for thousands of years.

It also supports the idea that interactions between humans weren't always as bloodthirsty as media would have you believe, and that they sometimes had offspring. Another interesting find regarding Denny was that her mother's genome was more like that of Western European Neanderthal DNA, who were found thousands of miles away, rather than the Neanderthals who actually lived around or in the cave, implying that Neanderthals migrated east in several waves, where they then encountered and coexisted with the Denny Sovins. And as if things couldn't get any more interesting, Denny's DNA also revealed that her Denny Sovan daddy had signs of exposure to Neanderthal ancestry himself, only just a lot

removed, with the minimal amounts being traced back to over 600 generations before his life, which in other words is an ancestor that lived about 18,000 years prior to you. And this might all sound rather insignificant, but in reality it's quite monumental, because this find represents the first direct primary fossil evidence for human species interbreeding. But with that said, there obviously is a ton of other direct evidence found in non-fossil form, in fact within our own DNA, which also gives proof to cross-species breeding. But to find evidence of it so clearly in a fossilized individual is a, unique, to say the least. So suffice to say, then he made quite the impression on anthropologists and paleontologists alike,

and we'll probably continue to do so as you learn more about her. However, if I was a betting man, I'd wager that we aren't going to find any more first-generation hybrids anytime soon. But you don't literally have to be one-of-a-kind to be extraordinary, which is best demonstrated by dinosaurs. Obviously, I, and I assume we, love these terrible lizards. And over the years, they have yielded some amazing finds. But perhaps the rarest dinosaur discoveries have been specimens collectively dubbed dinosaur mummies.

The name is pretty straightforward and actually describes it. As simply put, these are remarkably well-preserved dinosaurs, who despite being millions of years old, still have skin traces covering large amounts of their bodies, making them look more like an animal caught in a drought than a fossilized dinosaur. The first of these exceptional specimens to ever be found was a large in Montessaurus dug up in 1911, now dubbed AMNH 50-60. It was discovered during an excavation in Wyoming. and rapidly became big news with the body being in pristine condition and nearly fully complete at that,

with the sole missing pieces being the tail, back feet, and part of its pelvis. It was concluded that natural causes or perhaps dehydration had killed this amazing creature, who then dried out and was rapidly buried leading to its mummified-like state, which in turn allowed paleontologists to literally see what its skin had looked like, which in this case consisted of non-overlapping scales named tubercles that came into variations. The skin was also noted for being shockingly delicate and thin, especially when given the size the amount of a source. But what really blew them away wasn't seen in the skin, as so much more than that, was preserved. The fingers and hands were all kept well intact, while its nostrils

have been spared too. Even hundreds of tendons could still be seen along the body, a first in paleontology, so no small feat. And yet somehow, since then, this mummy has arguably been triumphed by even better preserved ones. And this includes a baraculophosaurus, nicknamed Leonardo, whose body is still 90% covered in skin, and even has preserved outlines of the muscles, making it seem like it died last year, not 77 million years ago. In addition to this, Leonardo was also maintained at parts of its cratinous beak, along with the frill and the remains of its last meal, which admittedly wasn't the most exciting, being a bunch of plant material.

Yet, inside the plants was something a bit more interesting and, at one point, lively. Worms. Delicious, unfortunately for Leo, these creepy crawlies aren't thought to have been a yummy snack, but instead a parasite which infected him. No Bueno. And then on top of Leo, we also have, of course, the infamous Borealisal-Pelta specimen that could pass for being asleep instead of a fossil. This early Cretaceouss Incalus was found in Alberta, Canada, within an oil sands mine back in 2017. And funnily enough, despite being one of the best preserved dinosaurs of all time, it was misidentified for a brief moment, as until its discovery, no land animal had ever been found in the oil sands.

and thus it was originally thought to be a plesiosaur or some other kind of marine reptile. But after a quick peak, it was pretty obvious that this was indeed an enchilosaur, and a nearly complete one at that. Given its amazing state, the fossil was instantly labeled as paleo gold, before it was even recovered, by the way, as that was a challenge in itself, as the mummy was high up in the rocks and quite sizable, measuring 18 feet or 5.5 meters, and weighing well over one ton. So it might not come as a shock that, regrettably, disaster struck during excavation.

and the mold meant to protect it gave way, allowing it to smash directly into the ground, which is also why the specimen has those large cracks all along it. Yet with some magic, elbow grease, and maybe some duct tape, it was able to be pieced back together, and thus giving us one of the most spectacular dinosaur exhibits of all time. Some of the memorable features of this dinosaur include preserved skin, armor, the actual placement of spikes, and its stomach contents, which in this case was made up of ferns, stems, wood, and oddly a smidge of charcoal. But alas, thankfully, no worms. Furthermore, something that makes it very unique is that it's the only dinosaur mummy in which

melanosomes are preserved, giving us a window into what colored might have been, with tests implying that adults would have had reddish, pinkish skin tones whilst alive. And if I had been this Boralapelta, I would be darned proud to be on display. Because, I mean, look at it. It's stunning. But I'm not sure if I could say the same for one more, quote-unquote, exceptional fossil, that has caught two prehistoric animals in a rather compromising position. To be frank, I'm talking about a fossil that has suspended animals, making love, and the only

instance in history of two vertebrates being fossilized in such a state. Yeah, they may be hard to believe, but across mammals, reptiles, fish, etc., there's only been a single fossil showing direct mating, and the suspects, turtles, of all things, though not any kind you find along the beach anymore, as the joint specimen consisted of extinct genus, Aleocellus, which lived throughout the Eocene and Miocene periods in a multitude of continents. And fun fact, the family to which it belongs to is the ancient Kareto-Kellidae, who are still around today, represented by just one exand member, the pig-nose turtle from Australian Papua New Guinea, who, mind you, is threatened.

Back to our fossil friends here, in the early 2010s, this specimen was collected in Messil, Germany. And though others of its kind have been discovered in the same location, this find was a lot different than anything previously seen, as it was composed to two distinct individuals who were intertwined and facing away from one another. Pretty PG, so you'd think. as in humans turning your back on someone is like giving them the cold shoulder, but in turtles, it's pure love, because that's how they mate.

Well, actually, it's not, but I guess these two specimens were a bit freaky. And we know it wasn't just plain wrestling or territorial fighting, as their tails were exactly aligned with how you'd expect mating turtles to have theirs. And then for just a tad bit more proof, detailed analysis and the size differences between the two fossils, as well as certain anatomical features, pointed out that this duo was without a doubt, a male and female pair. So, what exactly went so wrong for our two lovebirds here, or rather love turtles?

Well, it seems to have had something to do with the place they chose, as these guys wanted a spicy location, nothing ordinary, choosing to mate in a warm tropical volcanic lake that laid deep within a crater, the bold choice to say the least, and one that would cost them quite dearly. Now I know what you're thinking, this couple definitely wouldn't have willingly waited into dangerous waters, and you'd be right saying that, as in fact the top layer of the lake was probably safe. The issue was that deep below there were toxic gases and other nasty things that were being released by the volcano. And newsflash, mating in water for an extended time is quite exhausting, especially so for turtles. And it's believed that after becoming fatigued enough,

the pair sunk about 30 feet or 10 meters below the surface, thus exposing themselves to the dangerous gases. And here's the problem. Though they don't breathe water, this turtle belongs to a family with super porous skin, skin that's porous enough that it literally absorbs oxygen through it. Therefore, while they could technically hold their breaths, they could not close their skin, and the toxic, dangerous stuff quickly rushed in, thus killing the turtles, whereupon they sank into the volcanic sediment and would remain there for 47 million years, embraced as one. And that's quite a long relationship right there, and as mentioned, this is the only case like it,

seen invertebrates. Whereas I will say in insects and other invertebrates, they do have a quote-unquote head start, because despite still being rare, there are multiple examples where they fossilized mid-act. And lots of these cases consist around amber-trapped insects, but also extends to trilobites as well. And if you're curious about some other crazy amber specimens, check out the video I made on that just recently. But either way, I guess the takeaway in all of this is always be careful with what you're doing, because you never know if you're going to end up getting fossilized or when and how it happens. Thanks for watching, and until next time, on Extinct Zoo.

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