ExtinctZoo - When The Sauropods Just…Stopped

Episode Date: May 23, 2026

Once upon a time, the largest animals to ever walk were in the height of their golden age, but then rather suddenly they vanished, just like that. Why?

Over the 4 billion years of life on the speck of dust we call home, the Earth has seen countless walks of life come and go. And many of these groups have been wondrous and large within their own rights, but only one group can hold a title as the largest. And when it comes to walking at least, there is one clear winner. And that would be, of course, the dinosaurs, a diverse group of reptiles that came in just about every shape and size over their record-long rule, with many of them holding various size records as well. And yet, even amongst them, there was one group that stuck out like a sore giant thumb when it came to the same. came to stature, being the biggest animals to ever walk, period.

And that would be obviously the Sarapods. First appearing in the very late Triassic period just over 200 million years ago, this group along next ended up becoming one of the most successful animals to ever live, spreading out across the entire world, touching every single continent, and reaching sizes that were once thought to be impossible for terrestrial animals, with some of the largest members possibly even surpassing 100 tons in weight, which is for reference like 20 stegosaurus smashed together into just one superanimal. And because they were so large, we have a fairly good understanding and record of them, as the larger abone is, the larger the chance technically it has at fossilizing, which is why we

have something called a preservation bias, which in short means an organism or group preserves relatively better than others. And this partially explains why in some places there are so many gosh darn giant sauropods, like the morse infirmation. In such formations where dozens of saropods live also go to show just how successful the group was, with many considering them the the most dominant herbivores of the entire Jurassic. So here you have these extremely successful giants that are literally everywhere and preserve quite nicely, but then suddenly during the Cretaceous' Cennemanian stage, about 100 million years ago, they suddenly disappear, just like that. And this wasn't a slow vanishing, rather a pretty

abrupt disappearance that would strangely last for millions of years until one day at the tail end of the Cretaceous, they would just suddenly pop up once more, creating one of the most mysterious periods in paleontology that is now referred to as the Sarapod hiatus. However, here's the real perplexing thing about the disappearance of saropods. It was not a global phenomenon, only occurring in certain places, namely North America and Europe. Whereas on the flip side, incontinence such as South America, Africa, and Asia, we see that the giant long necks continue their reign, being undisturbed by the whole event, which obviously leads to the second question of why was only parts of the planet impacted while others were not, especially since the impacted areas

seemed to be far apart. It's almost as if one day every starapod passed a certain line, vanished. But again, why? And to answer this, it's best to start before any signs of trouble begin. So in other words, the late Jurassic. Now this was perhaps the golden age for Sarapods, who after a global warming event in the early Jurassic had taken charge and became the most dominant group across the entire world, including within North America itself. And this is well reflected in the fossil records of America, wherein the Morse information, we saw at least 24 were different kinds of rather large and sometimes giant saropods coexisting side by side, and they were also not all from the same group, instead being rather quite diverse.

And such a formation was not super atypical either, as around the world quite similar structures were seen in other environments, where an abundance of saropods seemed to have made up the majority of megafaunal herbivores. So clearly at this point things were going just fine for them, and one, like I said, can consider the late Jurassic to in fact be the saropods' global peak. But of course, everything eventually gets a reality check, and during the journey, Jurassic Cretaceous boundary, an interesting fork in the road appeared for our giant friends, as they were seemingly cold in great numbers, while the rest of dinosaur kind were left rather untouched, so pretty odd.

With this said, they did not fully disappear at this time, but overall diversity was slashed, with groups like the Diplodokids, and Mementia swords in particular, going from abundant to, well, not abundant. And while some try to explain this off as just some type of preservation bias, many think this reduction is actually tied to a forgotten extinction event, which marked the transition from the Jurassic, the Cretaceous, and this was known as the Tythonian extinction. To be honest, we don't know much about this event. But interestingly, just as is what is opposite to what was claimed to have given the

starpods a head start, many believe this extinction event was a cooling period of sorts, possibly spurred by volcanism or even an asteroid impact, as three large craters, each dated to the Tithonian, have been found across the planet, possibly playing a role in their demise. Regardless, though, whatever the cause was, it seems to been fairly minor and selective, disproportionately impacting certain groups, which in this case obviously included the saropods. And depending on who you ask, this extinction was the spark for the sarapod hiatus. As in North America, it seems that the group went into the early Cretaceous, extremely weakened and rare,

with only one group being somewhat abundant in the region, a rather obscure clade known as the Tureasors, who were partially characterized by compact heads, thinner tails, relatively large, long legs, and thick torsos. They had originally evolved during the Middle Jurassic in Europe, but eventually went worldwide. And it seems that in light of the Tythonian extinction, they were able to expand into North America as well, where they existed during the Earth Cretaceous, with one member, the Miroosaurus, being known from Utah from about 136 to 132 million years ago. While within the same state, there was also the Moabosaurus, with both being similar in size, being more on the small to medium size, with each weighing about 10 tons at their maximum. So, in fact, lighter than the heaviest known African elephants, while their height, on the other hand, was comparable to that of a large giraffe.

perhaps being slightly taller or maybe slightly shorter. However, these guys, though, were the new faces in town, so to speak. As contrary to past belief, it does turn out that some familiar faces had lingered on in the north too, primarily the Barakiosauri, who are, of course, named after the Jurassic icon, the Brachiosaurus. It seems that they, too, had overcome the odds, and had persisted into their early Cretaceous as well, being the largest animals left behind from the Golden Days, so to speak, and they could be significantly larger than their fellow Tereosaurus, with members like the abidosaurus being about twice as long and possibly three times the height.

And given the different build styles between the two groups, even other Brachiosauridae were more equal in their weight, as seen with the Sedarasaurus, for example, were still taller than anything else around, excluding other Brachiosauridae, of course. But with all this said, while these two groups were conclusive proof that Sarapods made it past the Jurassic boundary in North America, they were definitely sparse in the fossil record, as were Saropods in Europe, highlighting that the survival of these giants did not mean that they were thriving. And sure enough, it wouldn't be too long until they too would disappear. It's not agreed upon exactly what the last Sarapod was in North America before the hiatus,

but for now it does seem to have been the Bracosaurus, the Sonorosaurus, which lived in Arizona and was not exactly the giant size, weighing about 10 tons as well. And based on fossil dating, it's believed that this Sarapod disappeared some 98 million years ago during the San Armenian, the first age of the late Cretaceous, what would be the beginning of the Sarapod hiatus? As for the next 30 million years, North America would be void of these giants. And this would have created for quite the odd sight, as again, it wasn't dinosaurs as a whole that disappeared from the land altogether, just Sarapods, and thus creating formations that you didn't see anywhere else in the world.

It also makes you realize that many famous dinosaurs and animals never actually saw saropods, period. For example, Dinosukas, the Tyrannadon, Gorgasaurus, Albertosaurus, casmosaurus, Styracosaurus, Parasarolophis, and many, many more, would have no clue what a star pod was, assuming you could ask them, that is, making more than a few scenes from various movies, inaccurate in more ways than just one. And unsurprisingly, in light of their absence, roles were reshuffled, with Hadrasors. Visit BetMGM Casino and check out the newest exclusive, the Price is Right Fortune Pick. BetMDMDM and Game Sense remind you to play responsibly, 19 plus to wager, Ontario only. Please play responsibly.

If you have questions or concerns about your gambling or someone close to you, please contact connects Ontario at 1-866-531-2,600 to speak to an advisor, free of charge. BetMGM operates pursuant to an operating agreement with Eye Gaming, Ontario. Enchalosaurus and serotopsids taking on the dominant role of herbivores, or predators in the area evolved to take down usually faster or more armored animals, instead of saropods who are more massive, obviously, and generally slower. The hiatus also meant that North America, America had a low-sized ceiling compared to other parts of the world that retained their giants.

Now, what's interesting and a bit ironic is that it was during the sarapod hiatus when saropods elsewhere blew up in volume. And to understand this, you have to know that going into the late Cretaceous, the Titanosaurs were the most successful group of saropods. And in South America, Asia, and Africa, these guys were ballooning in size. I mean, we even see the largest completed sarapod ever to evolve, and that is, the 80-toned Argentinosaurus. And just in general, numerous absolute monsters are popping up.

Dreadnoughtus, Bruhavsaurus, Patigate Titan, etc. And even the more isolated Australia was getting in on the action, with one formation alone, the Winton Formation, bearing at least six large Sarapods, including the Australot Titan. And again, this was just one formation. There were other similar ones too, which all goes to show that it was only in North American Europe that Sarapods truly suffered. But why?

Interestingly, one of the first studies in the matter actually claimed that that in reality the North American saropods hadn't suffered at all, and that water was simply to blame for the strange fossil record. Specifically, it was around the hiatus that the Western Interior Seaway formed, which if you watched my previous videos we know was a sprawling inland sea that cut North America into two. And what was argued is that this invasion of water forced saropods more inland and into higher grounds, where fossilization was less likely to occur. And thus, they never truly disappeared, but rather just picked areas to live where they would not be preserved. But following this study,

numerous other researchers had some qualms with it, and a subsequent one pointed out various issues with original claims, citing that while starpods might have indeed moved around due to the flooding, they had definitely gone extinct in the region for some time. And this might again actually point back to the western interior seaway, as it did cause a massive amount of habitat loss, and would have marooned these giants, who, given their size, were more dependent on being in the right kind of place to survive. There is also another key part of the starpot hadas, which was surprisingly not a natural factor, but rather a fellow dinosaur, representing a rare possible documented case of a dinosaur

killing off another dinosaur. But don't get it twisted, because the accused was no predator, rather an or an ornithician, or rather the ornithetians. Okay, so while we tend to think of dinosaurs as all being the same, there were in fact three distinct groups, with two usually being responsible for large herbivores, and that would be, of course, saropods and ornithicians. And just like herbivores of today in the same area, there was some competition amongst these two groups. and it might have turned deadly for the saropods around this time. To be exact, it was the evolution of the hadrosaurs, or duck-billed dinosaurs, that might have played a leading role. At first, you wouldn't really think these two would clash, seeing that they were, well, quite different,

with saropods being high grazers and hadrosaurs lower. But you see, budding of the heads could have occurred between the large hadroosaurs and younger saropods, though it would have been closer to the same eye level and might have been gunning for the same food items. And because the western interior seaway had already shrunk the map, competition would have been extra fierce. Not to mention that armed with their complex dental batteries and longer mouths, it seems that the hadrosaurus had what they needed to successfully outcompete the saropods, which is reflected by the fact that the last saropods before the hiatus coincides perfectly well

with the first North American hadroids to appear. And then going across the pond to Europe, the situation was bad, but not as bad as in North America, with the sarapod hiatus gaping much shorter, lasting from the coniation to the Santonian, with a group, though, tending to be rare before and after this time as well. well. And interestingly, the factors seen in North America were also seen here. As while there was no western interior seaway, Europe was at this point a region of numerous islands surrounded by warm seas that were on the rise, and thus leading to less space. Well then, conversely, where in Ephesians were expanding, suggesting that they might have butt heads on these islands as well.

And then you also have to add in the fact that these islands were also much smaller than the two continents created by the western interior seaway, making extinction just that much more likely for saropods. And between Europe and North America, the northern hemisphere became large, and largely saropod-less, which if that's not a word, I'm making it one. Well then on the flip side, no pun intended, the southern hemisphere remained big. And for both this lasted for millions of years, until just like how the star-pod hated started, it also ended, abruptly, with staropods finally making their way back. Now, dating isn't conclusive, but for now it is thought that North America remained without

its long necks up until the very last days of the Cretaceous, with the group only making a reappearance during the final Maastrichtian stage about 68 million years ago. So almost 30 million years since they had vanished. And to just illustrate how long this disappearance really is, we are talking about a gap that's fifteen hundred times longer than what you think to be the ice age. I mean that time with the classic mammoths, humans of clubs and fur, saber-tooths, etc. But while the long necks had returned, they never did achieve their old glory, as it was primarily just one sarapod that returned.

Remember the Almasaurus, a rather giant tetanosaur that might have been between 30 and 80 tons, which if true would make it fairly equal in size to the Argentinosaurus. So a pretty strong comeback regardless, and ironically makes it the largest star pot to ever live in North America, despite also being the last. So far, this remains have only been found in southwestern United States, and it is believed to have migrated upwards from South America at the start of the age. The question is though, why did they come back all of a sudden? I mean, and and dinosaurs were still around and were arguably even better off than before.

And so, the answer might have had to do something with the original problem, the Western interior seaway. In the tens of millions of years after its formation, the inland sea had already drastically shrunk, increasing the map size, so to speak, once more, and allowing for more animals to squeeze in without the worry of extreme competition. And similarly in Europe, it seems it just like the problem, the solution to the hiatus was similar as well. As worldwide there was a major marine regression and sea levels plummeted, and thus increasing the overall land size of Europe, and also making it more accessible to the rest of the world. And while this next part is more More debated, the best hypothesis at the moment is that the Sarapods' big break in Europe

came from migrating Titanosaurus out of Africa, who successfully set up shop in Europe once again, and even led to a partial resurgence in Sarapod diversity, as multiple saropods ended up evolving, such as Ampelosaurus, Lehuika Titan, Abduite DeSaurus, and Petrus Titan. Interestingly though, unlike the Alamosaurus, the new Saropods in Europe often were on the smaller side, perhaps as a reflection of insular dwarfism, and we even seen in certain places, Katzig Island, the small staropods to ever evolve that were legitimately closer to you in size than they were to their giant relatives. And so, with the hiatus officially at close, and the

saropods back in the north once more where they belong, the future for these giants was looking bright, with countless possibilities on the horizon. And with this momentum, the saropods launched a second golden age that saw the rise of yet the largest animals of all time in a legacy that would last for an additional millions of millions of years. Not. I wish that had happened, yet sadly, we were never able to see a potential second golden age. As almost immediately after the hiatus ended, the Sarapod's plans were rudely interrupted by the KT extinction event, that in the North American's case, happened only two million

years after the return, and bringing with it the demise of the dinosaurs, well, the non-avian ones, which sadly included the long necks. And thus, once again, a new Sarapot hiatus began, only this time it would not End. Thanks for watching, and until next time, on Extinct Zoo.