ExtinctZoo - Antarctica Before It Froze

Episode Date: March 15, 2025

Antarctica today is ice on ice on ice, with a few penguins sprinkled in. But once upon a time, not only was there no ice or snow, yet palm trees, giant crocodiles, noodle mammals and... dinosaurs?

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To many, Antarctica has always been like this, and will presumably, always remain like this. However, that's not actually correct, as once upon a time, not only did Antarctica have less ice, but it was instead a world of lush greenery, highly bizarre animals, and owner to a rather tragic ending, making it in all senses a lost world. While Antarctica is today known as the loner of the seven continents, sharing no natural borders, it used to be much more social, in a sense, being located higher up and closer to other continents. In fact, for a good chunk of history, it was actually connected to the rest of the world, as for millions of years it was stuck to South America and Australia, or at the very least had land bridges, with them

allowing many walks of life to use Antarctica's stepping stone throughout time, including the dinosaurs. And we know this as researchers have found sauropod skulls in all three continents, which are nearly identical to one another, implying dispersion across the three. And along with passing through, a variety of dinosaurs and other animals decided to even settle down into Antarctica. as it was much warmer during the Mesozoic, thanks to a more northern latitude and in general warmer global temperatures, resulting in the continent having a mean air temperature of about 12 degrees Celsius or 53 degrees Fahrenheit during the Cretaceous. So warmer than many European countries of today, like Germany, for example. Therefore, instead of only having a handful of resilient animals, like today, Antarctica had a plethora of dinosaurs,

including theropods, enchylosores, hadrosors, and saropods. while in the waters, sharks and marine reptiles could be found in mass. Additionally, thanks to the more negotiable weather and increased precipitation, the landscape was unrecognizable compared to now, being very green instead of white, and dominated by expansive rainforests, where conifers, firms, angiosperms, and ginkos made up the majority of flora. So in other words, there'd be absolutely no way of telling that you were even in Antarctica,

and that's even with disregarding the dinosaurs. But as you probably can tell, dinosaurs, or at least, least the non-avian kind, are no longer found in Antarctica. And that's because, despite being situated on its own tectonic plate, and quarantining itself by drifting ever more towards the South Pole, Antarctica, like the rest of the Earth, still got its face absolutely rearranged, or so you could say, by the dinosaur-ending asteroid, which most likely sent a massive tsunami crashing into its coast and heated up air enough to cook anything caught in the open and creating catastrophic forest fires. Then, even when things cooled down, it still remained a bad situation,

because while eventually it wasn't on fire, it happened to keep cooling and cooling, thanks to the massive amount of dust, sulfur, and other nasty stuff that blocked out the sun, leading to much of the world, and Antarctica, freezing over. However, where people get it wrong is that Antarctica did not remain a frozen wasteland, and not only did it make a comeback, but it reached levels of life not even seen during the Mesozoic. Not to mention that in spite of the common idea that the Senezoic, i.e., the current geological era, is cold, Antarctica also became possibly warmer than even before, minus the fire part that is, which was all thanks to pretty much the exact opposite of an ice age, a super greenhouse.

Following the end of the Cretaceous, temperatures would start to tick upwards, which was a result of abundance of carbon dioxide being released, but from where is not certain. Nevertheless, this caused major changes to the climate, and the Earth steadily became hotter and hotter, with both the Paleocene and Eocene epochs being much warmer than today. In fact, during a climatic event known as the Eocene Thermal Maximum, 1, Earth may have been at its hottest point for the last 100 million years. And in Antarctica, you could have seen some unbelievable average temperatures of around 25 degrees Celsius or 77 degrees Fahrenheit. Which, just to put that into perspective, is like Kenya today. It also helped that even though it had moved south since the Mesozoic, the continent was still higher up than presently, hovering at around 60 degrees south.

This allowed many plants to spread out and colonize the continent that today would not stand a chance. And if you ended up marooned there during most of the paleogene, you might think you were on a tropical island. As palm trees, swamp cypress, and water lilies would be greeting you instead of icy plains and glaciers. 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!

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Hilton, for the stay. No one goes to Hanks 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 co-pilot in Microsoft Excel to look at his sales and costs. To help him see if he can afford it.

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you'd soon realize that it still was not the easiest place to survive, just for all different reasons. Currently, the largest terrestrial animal and predator in Antarctica year-round is a flightless midge, so the size of a small ant, so nothing too worrisome. Yet during those times, it was something far larger and scarier, a dinosaur. No, I am not joking, but I am also not talking about the non-avian dinosaurs, but rather just about the closest thing to one since their demise, a terror bird, scientifically known as Forest Rackeds.

Now you may be a bit confused, as these guys are notorious for ruling South America, not Antarctica. But that is where the land bridge I talked about comes into play, because it was still around after the Mesozoic. In the two continents, Mayo State connected, at least periodically up until 40 million years ago, allowing terroverts to come on down and wreak havoc, having large, powerful curved beaks that could rip and dismember prey, while also having very strong legs, which were equipped with giant sickle claws at the end, which allowed them to both pin prey down or poke them, and made these guys just a bit too close to Dramasaurus, for my liking anyways.

Furthermore, the one from Antarctica, while currently undescribed, was likely one of the worst kinds you could meet, as it highly resembled the Forrest Rackos, an abnormally large and predatory member that could be the same size as male ostriches, standing around 8 feet or 2.5 meters tall, and weighing in excess of 130 kilos or 290 pounds. So, you know, just about three wolves stacked together.

Yet, despite their size, they weren't three times slower than a wolf. Because thanks to their leg construction, they were insanely fast, running at speeds over 31 miles or 50 kilometers per hour, allowing them to chase down a myriad of prey. And they were probably the undisputed terrestrial apex predators of Antarctica, patrolling the forested areas in any grasslands. But considering that the largest pure terrestrial animal is now a bug, it does raise the question, of what the heck were the terrabirds eating? Well, that land bridge with South America

did not just bring down predators or birds, but also an army of mammals, that we know about, thanks to the La Maseta formation, which represents present-day Seymour Island and dates from the Paleocene to the legacene. And given this long time span, not everything found there lived all at once, yet it still gives us a good general idea

of what this lost world was like, back when it was green. And because the connection was with South America, Many of these mammals were the kind you associate with it, not Antarctica, like the Estrapatheria, a now extinct group of rhino-like mammals, which were herbivorous and among the continent's larger creatures, though only two are currently confirmed to have lived in Antarctica, the Trigonostylops, and the Andartodon. Both of them had weird and large specialized teeth, but I assure you that these guys were vegetarians. They just had some weird dentition, and they also widely ranged in size, as while both were at least Pangolin-sized,

the Antarctodon has sometimes been estimated to reach over half a ton in certain species. However, this is more speculative. But a much more confident and equally weighted mammal was the Notio Lofos, who might be the largest confirmed land creature in Antarctica since the dinosaurs, with adults weighing up to 400 kilograms or 880 pounds. So about the size of a modern-day muscocks, and they likely sustain their respectable statures on nutrient-rich-flowering plants that were once abundant at the time.

Now, these guys were not members of the Strapotheria, but were instead the topturns, an extinct order of ungulates that could in some cases be quite strange, as best demonstrated by the only other known Antarctic, the top turn, the Victor Lemonia. This was a far smaller mammal, but at the same time, a stranger one, as it had high nasal openings suggesting a possible noodle-like proboscis, which likely operated like the one seen in tapers, allowing it to grab vegetation that was otherwise unreachable.

In recent times, its nasal openings have also been interpreted as a pair of prehensile lips, like those on a moose, or perhaps even a weirder nose similar to what's seen in Saga Antelope that would have helped it filter dust, cool it down in the summers, and keep it warm in the winters, if need be. Now with all this said, while the Estrapotheria and lit top turns likely made up the biggest mammals in Antarctica, they were by no means the only one, and many other kinds could be found. including in undescribed Xenarthen, Gondwanathyrs, and even Meridio Lestidens, better known as the saber-toothed squirrels, thanks to their enlarged teeth,

who were also possibly the continent's most dominant insectivore in one of the oldest residents, seeing that this group had been around during the KT extinction event and had managed to survive, likely thanks to their smaller bodies and diet. And then to finish it all off, you had yet another unexpected face, marsupials. When you think of a marsupial, you probably pick up. picture this, or this, or even this, basically all Australian animals. And while they may have made a good home there, they actually first evolved in South America, and thus leading to their presence in Antarctica, where it is there that they actually moved on

to Australia, because like I mentioned, the two continents were connected as well, at least for a part of the Cenozoic. So far, three groups of marsupials are known to have made it down to Antarctica, the Deroor Hincah, Polydoliphamorphia, and Microbiorea. Unfortunately, almost nothing is known about the first group, but we do know a bit more about the second one, and understand that they were quite diverse in appearance and could fill many niches. Meanwhile, the third group, Microbiotherapy, we actually know quite well, seeing that they are still living, albeit not in Antarctica.

With the sole extent member being the Monito del Monte, meaning Little Monkey of the Mountain in Spanish, and it can be found in Argentina and Chile. Interestingly enough, though, these guys are more related to Australian marsupials than its fellow South American ones. But that's besides the point. With the real point being that marsupials and many traditional ancient South American mammals are what largely made up the Antarctic environments, and thus supplying more than enough food for their terror bird overlords. And it wasn't just bird that mammals had to watch out for, as another carnivore made these lands home too, and the waters for that matter, which is one that you would never imagine in Antarctica today.

crocodiles, or at the very least, some kind of crocodileian. For a long time, paleontologists have guessed that crocs lived on the continent, given its land bridges and previous temperatures, but they never actually found anything conclusive until the discovery of a giant osteoderm dated to some time in the eocene that exactly matched those seen in both living and extinct crocodilians. Therefore, we know it was a crock, but what kind is uncertain. But what we do know is that it was a giant, as the osteoderm in question was about the size of one you'd expect to find on a 23-foot

or 7-meter-long crock, so about 15% bigger than the largest saltwater crocodile ever recorded, and about 35% greater than the average one. So this would technically give the crocodiles the title of the largest predators on land, if we were including semi-aquatic creatures. Furthermore, they were likely opportunistic ambush hunters, that dominated freshwater environments and potentially inhabited brackish and even saltwater, too. kind of like how the saltwater crocs can today, which would have, of course, brought them into contact with many mammals,

and made sure that you could never remain completely safe when you went for a drink, especially since its large size meant that absolutely nothing was completely off the menu. And interestingly, but perhaps not surprisingly, evidence shows that this mysterious reptile was not alone, as other fossils located not so far away, implied that there were also crocodiles in the area that were more specialized, namely possessing paciferous diets. But again, not much else is known about this crock either.

Though it does tell us that when Antarctica was green, virtually every animal could expect to be eaten by a crocodile at some point. And this included a very familiar face, who was actually the only animal I brought up so far that still lives in Antarctica, penguins. Now, we typically pair these guys with the cold, so it may come as a surprise that they were still around back when Antarctica was much warmer. And it was in the heat that penguins actually got their start, as they probably evolved off the coasts of warm Australia and New Zealand around 60 million years ago, and then made their way to Antarctica

where they then thrived. And if the continent is considered a penguin paradise today, then it was an absolute penguin heaven back then, because now only two penguin species call Antarctica their full-time permanent homes. Yet during the paleogene, this number was more like 16, with each one being a bit different from the last. Yet it wasn't just the numbers that were surprising, but also their diversity in size, as prehistoric penguins were absolute units, with three of the 16 species being what scientists call giant penguins. Presently, the largest penguin on earth is the emperor penguin, which can be 100 pounds or 45 kilos and stand at a maximum of 4 foot 11 or 1.5 meters, which is definitely impressive in all, but is still an absolute small

fray compared to two of the ancient giant penguins, specifically anthropornis and Palae Eudiptees. Both of these guys were Titans, who at their biggest could have stood at around 6 foot 9 inches or over 2 meters tall. In other words, taller than Michael Jordan. And they were heavier too, thanks to the robust builds and blubber, with adults weighing 108 kilos or 238 pounds. And the polyutops could be even bigger, weighing 116 kilograms or 256 pounds. So in other words, we're talking about a penguin larger than a jaguar. So you already know, being slapped by one of these guys, most likely her. hurt. And they were also pretty nifty in the water, likely being able to hold their breaths

for over 40 minutes, and thus allowing them to wreak havoc on squid, fish, and krill. Now you might be thinking, why were they so big? And the answer is, is that it's thought their giant sizes may have been for energy conservation purposes. But even with their size, it still wasn't enough to ward off crocs if they swam into one, nor did it likely stop the other nightmares that patrolled the coasts, and what were essentially the Times Mosasaurus, Cetaceans. Obviously, there are still whales in Antarctica today, who can definitely be a bit scary in their own right.

But the paleogene ones were somehow both scarier and even bigger, too, with two genera being known of so far from the Lama Seta formation. The first one was almost certainly an apex predator, as it was an undescribed basilosaurid, who were typically large, serpent-like, and specialized to be predators in shallow waters, coming equipped with massive skulls and equally giant teeth that could easily penetrate skin, muscle, and bone. And based off of at least one located mandible, it's possible that this enigmatic bacillosaurid might have measured up to 40 feet or 12 meters long, and most likely fed upon anything the

right size that it came across, which might have included now giant extinct sea turtles that once reached up to 10 feet or 3 meters long, so bigger than any turtle we have around now. And while not as predatory as the bacillosaurid, you also had the lanocetus swimming around too, The whale who visually could be even more terrifying, as this remains imply that it was absolutely colossal. For now we only have the bones of a juvenile, but here's the thing. This juvenile was freaking massive, being about the same size as the largest known adult orcas,

so who knows how big the adults got. But just going off of what we know about modern-day whales, it most likely rivaled humpbacks in size, depending on just how old the youngling was. And this is terrible news, as these guys were likely much more bloodthirsty than the same. than humpback whales, despite though also being baleen whales. You see, back in the day, balines actually still had teeth. In this extended to lanocetis, who could use them for uptorial behavior or to help trap prey as its suction fed, since its facial construction was a bit like that seen

in modern-day beaked whales. There's also a chance that it was a hybrid predator, both hunting and using suction feeding leading to a very diverse diet where almost nothing was safe, which is only further emphasized by its presence in both river deltas and the open ocean. So given its size, it could have snacked on a variety of fish, penguins, cephalopods, and even sharks. And actually, lots and lots of sharks. Because opposed to today, prehistoric Antarctica had an exhausting list of sharks. I mean, it was in some ways the Australia of the paleogene.

And so some of the groups you could find included Requium, Goblin, Gulper, Carpet, Kitefin, Longnose, School, 7gill, 6gill, hound, smooth hound, sand, angel, and saw sharks. Yeah, I did tell you it was exhausting. And even this wasn't the full extent, as you had three more interesting residents too, such as an extinct species of basking shark, the mackerel shark that was possibly the ancestor of mako sharks, and then the most fascinating, or perhaps terrifying, of all, the megalodon. Well, actually, not 100% the megalodon, but basically, as these were actually two species that belonged to the same genus that the megalodotan did,

the odotis, meaning ear-shaped tooth. Specifically, researchers know that odotis Sokolavi and Odidus Arculatus prowled the coastal waters of Antarctica where they were apex predators and presumably came into conflict with the coexisting giant whales, as these guys could be absolutely huge. The smaller of the two was the Sokolavi, which had finer serrations than most odotis and typically grew to be 6 meters or 20 feet long.

So still pretty big, and about the size of the biggest great whites in the oceans today. Now the Arculatus was far bigger, with the largest specimens measuring 9.5 meters or 31 feet. So not as long as its cousin the Megalodon, but still large enough to ensure its place as a top predator. And based off what we know about the Otitis in general, we can assume that these two likely fed on fish, turtles, other sharks, and possibly even whales. Their presence, along with the rest of the sharks, made pre-stork Antarctica's waters deceitfully deadly compared to now, and a chaotic place for penguins and really anything else that called the waters home. But penguins weren't the only birds that had to live on edge, as a huge amount called

the area home. And birds access in Antarctica, through the paleogene, actually tells of an interesting story, as some paleontologists believe that it was actually here that the first modern bird ever evolved, the vagavis. Now, this bird never made it out of the Mesozoic, but its presence on the continent represents just how important Antarctica was for bird evolution. What's more is that some also think that birds mainly survived in Antarctica following the asteroid, and thus possibly explaining their large numbers and high diversity.

And thus far, we know that falcons, ibis, albatrosses, and petrels were all present at the time. Plus you also had the strangest bird of them all, who happens to be the only one now extinct, the disorness. It was a member of the Pelagronithidae family, who were hard to miss thanks to their odd teeth, or at least what looked like their teeth, as these birds in truth did not have any teeth at all, but rather bony projections from their jaws, which just looked like them and gave them a rather freakish appearance. It also didn't help that most of the members of this family were massive, desornous included, with an estimated wingspan of about 16 and 20 feet or 5 and 6 meters, so you know, just akin to the wingspan of a small plane. Or if you

you prefer terosaur analogies, it was about the same size as a Tyrannadon. Not to worry, though, because in spite of its appearance and size, the disorness was a bit of a softy, literally, with its fossils of being abnormally fragile, which in life most likely kept it restricted to just hunting fish and cephalpods, which it did by skimming the surface of the waters and sniping any unfortunate prey that was too close to the surface. And there you have it. Before the ice, Antarctica was a chaotic but vibrant world, full of strange and terrifying animals. Which leads us to our final question,

where did they all go? And sadly, the answer is not a pleasant one, as most of the continent's inhabitants met a fairly tragic ending, with this tropical party having come crashing down during the final days of the Eocene. And if you somehow found yourself in Antarctica at that point, you'd be guaranteed a pretty grisly ending, unless that is you were a very lucky penguin or bird.

And it almost seemed as if Mother Nature had a vendetta against the continent, as everything that could go wrong did, and did so pretty much all at once. The exact timeline is blurry, but it may have started with the continent completely separating from the rest of the world, and thus creating the Drake passage between it and South America and the Tasmanian passage with Australia. This isolation meant that any animals on the continent were now stuck, which is not necessarily a problem within itself, considering that Antarctica is quite big, yet the issue is that as this problem arose, so did another much more troublesome one. For over 200 million years,

the earth had been pretty warm, and at times very hot. And then, rather abruptly, this all started to change about 34 million years ago, when temperatures just started to plummet, which ironically is possibly thanks to Antarctica's isolation. Because as the passages opened up between it and its previous neighbors, it led to the formation of the Antarctic circumpolar current, a major current of cold water that surrounds Antarctica even today and blocks warm waters from reaching the coasts while also absorbing carbon dioxide. This, in addition to its southward movements, resulted in the first ice sheets starting to form in marking the onset of the late Sinozoic Ice Age, which, by the way, we are technically still living in. The bitter cold weather

that would have accompanied these events ultimately eradicated most of the native life, for the changes being just too rapid for most to adapt, while the ice itself caused habitat loss on an unprecedented scale. Although it wasn't the end of the story yet, as the continent still had areas without ice sheets, where the last survivors could have sought solace. But the relief, like many things, was only temporary, as over the next seven million years or so,

the continent slowly succumbed to the ever-expanding ice, until it was virtually covered. And of course, to add salt into the wound, the effects of the cold only worsened as these ice sheets. grew since they reflect massive amounts of heat from the sun. And as you can probably figure out, the continent has remained in this perpetual icy state, mostly unchanged. And while we do have the Lama Seta formation, there is no telling what could be hidden beneath all the ice in the rest of the continent. Although honestly, to find that out would probably require a lot of pain that I at least

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