ExtinctZoo - The T. Rex's Savage Older Brother

Episode Date: February 8, 2025

We all love and know the T. rex, but have you ever asked yourself, where did it come from, and what ruled before it? Well.. here's the answer.

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Save up to 40% your first year at LifeLock.com slash special offer. Terms apply. 65 million years ago, the plains of prehistoric North America were being dominated by the infamous Tyrannosaurus Rex, the Tyrant King. Thanks to its immense size and Titanic Jaws, its reign was absolute, and helped make a name not only for itself, but for its family too, the Tyrannosaurus. And while famous, none others in the family have come even close to obtaining the T-Rex status of fame and infamy, even though the Rex wasn't the first member of its family to arise, nor was it even the first to rule Nor was it even the first to rule North America. As just a few million years before, a very close relative was already playing the role of big bad wolf and happened to be the second largest Tyrannosaur to ever rule the continent.

This being Daspletosaurus, meaning the frightful lizard. Unlike many new discovered Tyrannosaurs that are found in poor condition, the first known Despletosaurus specimen was greatly preserved, consisting of a complete skull and over 50% of the body, including the vast majority of its vertebrae. This helped the researchers instantly recognize that they discovered a massive monstrous Tyrannosaurid, but there was still a lot of initial confusion, as the skeleton was very similar to previously described genera, and it was ultimately misclassified. And for 50 years, it remained not a new genus, but rather a new species of gorgasaurus, simply because the two had similar teeth and superficially seemed similar, mainly in size.

Eventually, a curious paleontologist re-examined the holotype and realized it was much more of a chunkster than the gorgasaurus was, having a denser and bulkier body, while the skulls of the two weren't really that identical beyond the teeth, with despletosaurus's head being more wide, resulting in it being reclassified as a new genus, with the holotype being dubbed daspletosaurus, terosis, with the latter part to meaning muscular,

which was taking inspiration from its monstrous head and body that actually turned out to share more similarities with another genus, the Tyrannosaurus. Upon further analysis, it turned out that this new predator was a lot like the king, with the two being so similar that a few times, paleontologists have tried to reclassify it as a new Tyrannosaurus species, and it's honestly harder to point out their differences than their similarities, with the only clear discrepancies being that dyspletosaurus was a bit smaller, had different bone density, relatively longer arms, smaller feet, and more prominent crests in the front of the eyes. The brains were also different in shape, but both still had

some features that were generally not seen in other Tyrannosaurus, including a tall eye socket and expanded air pockets within the skull. They also happened to live very close together in time, with Desplatosaurus existing between 78 and 74.4 million years ago, while the Tyrannosaurus popped up just 1.7 million years after. This closeness, combined with their lack of differences, created a lot of interest in the relation between the two and where this new genus fit in the family overall, with some even suggesting that it is what eventually became the T-Rex itself. In other words, it was a direct ancestor. This hypothesis was further developed after studying its evolution through time, as over the years researchers discovered two more species belonging

to it, Daspletosaurus Wilsonie and Hornary. which together with the original species, seemed to demonstrate a pattern of becoming more derived in Tyrannosaurus-like over time, at least according to one paper, which concluded that through anogenesis, the Dasplatosaurus lineage ultimately gave way to the Tyrannosaurus. Now, not everyone is on board of this idea, and some still retain that it wasn't the T-Rex's direct ancestor,

with one of the main arguments being that deciphering an extinct animal's true predecessor is nearly impossible without DNA, in that even though 1.7 million years is not a huge gap, in a broad sense, it's still big enough to leave room for a lot of questions. In a recent find, which demonstrates this, is a recovered tooth that remains unassigned to any genus, but boars a striking resemblance to the teeth seen ensue the T-Rex. A perplexing find is this fossil dated to 77 million years ago. So, in other words, before the Tyrannosaurus, but at the same time of the Daspidosaurus,

hinting that other potentially more T-Rex-like theropods were roaming about. Nevertheless, even those who think it was not the progenitor of Tyrannosaurus, still agree that they are extremely related. And many recent cladograms have it as being the most closely related North American Tyrannosaur to the Tyrannosaurus genus, and the second most related to the specific species, T-Rex, with the only one being ahead of it being in the King's sister species, the Macrensus. And what's more is becoming more in the species,

intercepted that each of the three species were in fact on a trajectory of getting more derived, as the study stated. But they were still largely the same, with the biggest differences being seen in the skull and in their sizes, with the pterosis being the largest, trailed by Wilson E, and lastly, Corneri. Although, all three were still giant by modern and even prehistoric standards. And across the board, matured specimens are believed to have measured between 8.5 and 9 meters, or 28 and 30 feet, while standing 2.2 meters were 7.2 feet tall at the hips. And thanks to their robust builds, they were also pretty hefty, for theropods, weighing up to 3 tons, which puts them in the upper echelon of North American pyranosaurs when it comes to size.

However, thanks to a few monster specimens, we know that they got far bigger. With the biggest specimen to date, a terrosis individual named Pete III, or Pete 3, likely measured some 11 meters or 36 feet in length, and weighing a gop-smacking 5.5 tons, making it the second largest North American Tyrannosaur, genus, and the biggest predator in North America during its existence, giving it undisputed apex predator status. So obviously, the Daspletosaurus got those good Tyrannosaurus genes, or perhaps it's the other way around.

But regardless, it apparently extended to its skull, which was massive in its own right. with most reaching more than one meter or three feet long, and were constructed like the carcinamad max. In other words, like tanks, with the bones being unusually heavy and robust, while the nasal bones at the top of the snout were fused together in order to maximize strength. And to match the intimidating muscles and bones this skull has,

the Dasplatosaurus possessed a mouth filled with over six dozen teeth that were extremely long, pointed, and oval at the cross-section, hinting that like its future relative, it had a bite built for terrifying power, as the oval cross-section provides durability and stability to the base of the teeth, allowing them to withstand a men's power when crushing down onto their doomed victims. And indeed, studies have found that it did possess a wicked bite, with one even suggesting that it had the strongest bite force in its entire family second to the Tyrannosaurus, while also having the second largest deductor jaw muscles, and the third greatest cranial stresses

after the tarbosaurus, all creating a bite powerful enough to pulverize tough armor and cause bones to literally explode upon impact. Some scientists believe that it hunted a lot like the T-Rex too, given its bite force, using a puncture and pull method, which involved using an initial powerful bite to penetrate and grip a victim that was then swiftly killed as it was pulled backwards, tearing off massive amounts of muscles, organs, and bone simultaneously. Based on its environment and what animals it was found alongside, paleontologists reckon that as pletosaurus's diet

mainly consisted of a variety of large seratopsids, hadrosores, and anchylosaurs. But ultimately, anything caught was its diet, as one matured specimen demonstrates, having a stomach full of the digested remains of young small hadrosaurs. Its titanic jaws were definitely not great news for any co-existing dinosaurs. And if they wanted to keep safe, there was only one drawback to its build that could be exploited, and that was speed. Due to its tanky nature, it wasn't the fastest animal around, and was probably restricted in what it could go after,

likely relying on surprise attacks to catch other dinosaurs off guard. Though the upside to this reduced speed and great robustness was the benefit of durability, which meant that armored herbivores, who were usually pipe dreams for most predators, were actually viable targets for desplatosaurus. And it did have other tools that made up for its lack of dexterity, one ironically being its arms. Ironically, because Tyrannosaurs are famously known for comically short arms. And while not massive, Daspletosaurus did have the longest four limbs of any Tyrannosaur relative to its body size,

with each being up to three feet or one meter long. They were also deceptively strong given their narrowness, indicated by thick bones and lots of attachment points from muscles, possibly enabling them to catch and hold on to struggling prey trying to escape. Its tail likely helped in combat too, being remarkably heavy and powerful, helping to give it amazing balance that proved invaluable when scuffling with the largest herbivores, who could, of course, be pretty big, to say the least. And though not graceful like a cat, it did have some feline-like senses,

or rather crocodilian-like, as there is evidence of integumentary sensory organs that came in the form of large plates located on its snout, which possibly gave it the ability to modulate precise jaw movements, re-temperatures, and detect prey, while also providing, of course, additional armor to its face. Suffice to say, Despletosaurus was kidded out, and yet the most broken aspect about it may not have been found on the body, but rather around it. Other despletosaurus. Over the years, specimens have been found next to each other in groups, indicating a certain level of socialness, with the most prominent discovery being a cluster of three individuals which ranged in age and size,

and were found next to five hadrosaurs. Studies in the sediment and bones concluded that all three had died at the same time whilst feeding on the dead hadrosaurs. And because age gaps were present, certain paleontologists believed this find represented a familial pack. And this would make sense

as other closer related tyranosaurs are also known to sometimes have grouped together, like the gorgasaurus and albertosaurus, thus increasing the chances that Aspletosaurus really was a gregarious creature. And these family-based packs would have been exceedingly annoying for prey, as the range in size meant you had younger, faster members who could catch and disrupt herbivores, while the older units would come in to finish the job.

And this problem is only doubled when you further consider that the young stayed small for quite a length of time, with one analysis of bone growth finding that juveniles did not see much growth for the first five years of their lives, before then undergoing rapid weight gain and size, which lasted for about 15 years. And while the evidence for familial groups is pretty strong, another contrasting belief is that it operated more like Komodo dragons, in that non-cooperative individuals would mob prey in carcasses, leading to pretty much all-out gorefests, and leading to frequent conflict amongst esplodosaurus. To lend credibility to this view, we know that in general it was a tough lover, with many of them experiencing their worst injuries from the hands or jaws of their own.

A unique trend has also been identified, which shows that biting each other's face was the preferred method of introspecific fighting, and was extremely common, with numerous specimens containing dozens of bite marks to their skulls, which were also inflicted with enough damage that they were left with deep grooves. This ill-tempered Tyrannosaur is also one of the few theropods known to carry out both non-fatal and fatal attacks in competition, seeing that sometimes the marks never fully healed, implying death. The most commonly thought to reasons behind this violence is territorial disputes, fight over resources, or over dominance within a social group.

A grumbling stomach appeared to be a trigger too, seeing that one dyspletosaurus skull found in Alberta, Canada, had bite marks that healed, but also ones, which not only didn't heal, but had zero signs of inflammation or any sign of bone growth, heavily implying that they were made after death by another despletosaurus that was scavenging its carcass, and providing the first evidence that this carnivore was a carcass, and providing the first evidence that this carnivore was a cannibal at times. Now why exactly it would choose to turn on its own is a bit of a mystery. But the answer could lie in its environment, which was known to experience periodic droughts and natural disasters, resulting in mass mortality and chaotic conditions, thus potentially forcing despletosaurus to turn on their own. Another explanation presented is that if it truly did mob prey and carcasses, then during the carnage, it might have been normal for an unlucky individual to get caught up in the frenzy, becoming a little snack themselves.

So obviously being a despletosaurus had to be at least a little bit stressful, always needing to watch your back for others of your own kind. And interestingly enough, it wasn't the only Tyrannosaur that could get caught up in its shenanigans, as Despletosaurus is among the few examples of a tyrannosaurid that lived alongside another. In this case, the Gorgosaurus. Back in the late Cretaceous, North America was divided into two, thanks to the presence of the Western Interior Seaway, creating the island continents of Laramidia to the west,

and Appalachia to the east. Now Dasplatosaurus was found solely in Laramidia, where it was joined by the Gorgosaurus in at least three different formations. Like the former, Gorgasaurus was a really large predator, and one of the biggest North American theropods of the entire Cretaceous, with individuals measuring up to 9 meters or 30 feet. It also had a pretty giant skull and ferocious bite, making it probably the only animal that could actually threaten the daspletosaurus.

But don't you worry, because our guy had an advantage. and that was its signature tankiness. While the two were similar from the side, if you looked at them from the front, you'd clearly see that the frightful lizard was way bulkier, leading to a stronger body, more powerful bite, and heavier weight, with the gorgasaurus tapping out at three metric tons. Therefore, it's safe to assume that adults were still secondary

to large despletosauruses, although they did get the benefit of speed, with their lighter skeletons and nimbler legs. While fights no doubt happened at least a couple of times, their differences is actually what allowed for some breathing room, as the two likely developed their own ecological niches, with Gorgasaurus hunting faster, smaller prey, and Daspleetosaurus, preferring slow, better armored giants.

And this could be why the two seem to have their own separate kingdoms, with the despletosaurus being more common to the south, while Gorgosaurus ruled the north. However, due to the sporadic growth patterns seen in the Despletosaurus, paleontologists do think that conflict could have been rampant with the adolescents, given their smaller sizes and greater speeds. Not to mention that, as stated, the adults still did occasionally hunt prey that weren't exactly slow poaks.

But ultimately, there was enough food to go around, typically, as Laramidia was abundant in life. At the time, the Rockies made up a good chunk of the island continent, forming many large rivers that ran from the mountains down to the seaway, helping create vast, rich environments like floodplanes in which the dust platoosaurus could be found. This combination of rivers floodplains and the coast created a huge blend of diverse animals, namely dinosaurs, but is by no means limited to, the Edmontonia, Scolosaurus, centrosaurus, chasmosaurus, cyracosaurus, corithosaurus, gryposaurus, lambiosaurus, perisorolophis, Stegoceris, Ornithomimimus, Apatoraptor, Albertonichus, Etroseraptor,

Truthiomimus, Radovates, Cidopies, Chirostenatis, Sauronithelestes, and Dramasaurus. Meanwhile, non-dinosaurs were everywhere too, being represented by over eight different invertebrates, 20 fish, including sharks, 20 mammals, 10 turtles, five lizards, and multiple pleasios, terosaurs, camsasores, and crocodilians. And while no conclusive proof has ever been found, there is also a chance that as Pleidosaurus met a lot more dinosaurs, and life across the pond, so to speak, considering that the distance between the two continents wasn't that great, allowing for some to potentially end up in Appalachia,

though most of the time there was simply no need to venture elsewhere. This being said, this island paradise, which held the semi-tropical climate, could get a bit sinister at times, demonstrated by multiple mass mortality events which took place periodically. Based on the sediment, paleontologists believed that the biggest perpetrator of these great die-offs was extreme volcanism that stemmed from the western side. It could blanket the entire island in layers of thick ash and causing massive forest fires,

resulting in widespread problems and deaths, but also enriching soil for the future. While less of a problem, Laramidia was subjected to the occasional droughts and sea level fluctuations as well, which again helped to keep things lively, but sometimes probably a bit too lively. And for those who don't believe

that it kept evolving and instead went violently extinct, these disasters are thought to have been a potential murder weapon to have taken out the despoletosaurus since it was restricted solely to this island and thus making way for a new family member to rise up and eventually take the throne. Thanks for watching and until next time on extinct zoo. Ambition comes in all shapes and sizes. At First Citizens Bank we roll with your goals because we're built for what you're building. Fit for your ambition for Citizens Bank Own it all. Pay off your home, travel for life, drive a Ferrari.

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