A Mega Megaraptora Episode

This episode is brought to you by Herd of Horns, an awesome new tabletop role-playing game where you lead a herd of seratopsids through challenging landscapes, fending off predators and outsmarting rivals. The campaign ends soon, so go to iNoDino.com/HerdOfHorns to back it like we did. Hello and welcome to iNoDino. Keep up with the latest dinosaur discoveries on Science with us. I'm Garrett. And I'm Sabrina. And today in our 575th episode. We have a mega mega raptor episode. Oh yeah, you teased that last time. Yeah, this was a request by a few of our patrons, so it's been a long time coming. And we talk about this enigmatic group of carnivorous serapods. They have huge arms and handquas, which is unusual for large serapods. We also have an update on mega raptor and an overview of all-known mega raptorons. Wow. Thorough. Yes. Plus, we have our dinosaur of the day, a nexusosaurus, a possible mega raptor that was also possibly gregarious and bonus because I wanted to be thorough. We also have a owner raptor, a mega raptor, and with a lot of air spaces in its tail bones. And our fun fact for this mega episode is that paleontologists originally considered mega raptors' handclaw to be a giant footclaw. And funny thing is the opposite happened with Velociraptor. That is funny. But before we get into all of our mega raptor action, we've got some patrons to thank. And this week we have four new patrons to thank. And they are L Velociraptor on theme and Josephine. And then rounding out our shout-outs, we've got Rachel Raptor. All right. A couple raptors. Yeah. Serosaurus Rex, Jurassic Jim, Allo Mary, Steph, and Carcavodontosaurus. I wonder, though, for the raptors, if it's more like for the Velociraptor, the Dremea Saws than the mega raptors, yeah, we don't know. Maybe they can let us know. Yes, thank you so much for being part of our Dino at All community. We really, really appreciate it. And it's thanks to Dino at All's that we get to do episodes like mega raptor episodes. So if you want to join, we've got plenty of perks and exclusive content. You can access things like our monthly I Know Paleo show, as well as many episodes, because tries we might, we can't fit all the new dinosaur news into regular episodes on I Know Dino. So you can do all that at patreon.com/I Know Dino. So yes, mega raptor episode. We had a few requests. I want to thank Tales of Extinction and Morgan, who requested this mega raptor in episode to quote Morgan. It wasn't just Tyrannosaurs in the North and Abelosaurs in the South. True. Mm-hmm. Don't forget the mighty mega raptorans. Yeah. And the other raptors. Well, they're much smaller. True. So mega raptor, mega raptorans, they had long skulls and big claws on their hands. This group lived in the Lake Cretaceous. They've been found in Australia, Asia, probably Europe, Africa, and South America. Pretty much the whole world. Yeah. I guess not Antarctica so far. A 20/25 study found that mega raptorans may have had a cosmopolitan distribution, meaning they lived all over the planet, before lurasia and gondwana split, which is fairly early on. Yeah. You didn't mention North America either. But I feel like there has been at least some proposed mega raptorans from North America. If there are some, those are the possible mega raptorans, not for sure definitive mega raptorans. Because for this episode, I researched all the definite known mega raptorans, and then I kind of just skimmed over the potential mega raptorans, but I don't remember reading any that were North American. There is on the paleobiode database in the Cedar mountain formation. That's where sea otts is, which is maybe in mega raptorra. That's the proposal. So that's in Utah, but that's the only one on the entire North American map. Yeah. And you're right. There's nothing in Antarctica. No, although they probably traveled through Antarctica. Yeah. It's more that we don't have a lot of rock to work with in Antarctica, so we just haven't found it yet. Yeah. Mega raptorans, they're carnivorous. They're therapists, they've got the strong arms, the large claws on their hands. And that's what makes them so interesting is because other large therapists usually had smaller arms. Yeah. They mostly replaced their big hands and grabbing ability with a big powerful skull, but mega raptorra, not so much. Most species of mega raptorans, we know only from fragments, which is too bad, no complete mega raptorous skeleton has been found yet. And mega raptor has often described as an enigmatic group or a mysterious group you could say. Yeah. Partially because of the fragments and also because why did they have such big hands and claws on their hands? They were highly specialized predatory therapists. So of course, they had the well-developed arm bones. And as mega raptorans evolved, their muscle attachments on their arms got even more developed. This is according to a 2023 study. So like you're saying, Garrett, with other big therapists, they kind of evolved to have the bigger heads, but mega raptorans as they evolved, they got stronger arms. Yeah. Mega raptorans had three fingers on each hand. The first two fingers were long with the large curve claws and the third finger was small. Yeah. I always think of it as like the biggest finger is the first finger and then they kind of get progressively smaller down the hand. Yeah. Different than our hand. It's like if we had the middle finger switched with the pointer finger kind of. Yeah. The pointer finger was a lot longer. A mega raptor had a vestigial fourth hand bone, but it didn't have a finger attached, which is interesting. Mega raptorans could likely do complex movements with their arms and their hands. I want to just quote tales of extinction here who said, given the large claws and moderate bite strength, I wonder if it specialized in hooking smaller moving prey that it could easily overpower like crocodile morphs, a spear fisher on land. I didn't see anything specifically about mega raptorans and crocodile morphs, which is too bad, but I will get into later a bit about how they use those arms. Now mega raptorans, they also had wide belly ribs or gastroia and that means that they had wide bodies. They had long foot bones, which is an indication of being a fast runner. Their leg bones were slender and similar to salura sores that could run, which also indicates running. And they may have had deep muscular tails that's based on ridges on the back bones or dorsal vertebrae. Their bones were heavily pneumatized, so lots of air sacs to make them lighter, especially the vertebrae ribs and ilium in the hip. And what's interesting about that is we only see this kind of pneumatization outside of mega raptor in neovenator or neovenator, which is a carcara dontosaur. Some mega raptorans like Marous raptor and aerostion had very pneumatic bones in the hips and the ribs, which were likely like modern birds and housing sinuses connected to the lungs. Oh, that's cool. So they were actually using the air sacs for improved breathing. Yeah. Omega raptorans, their neck bones or cervical vertebrae were epistocelus. That means they were convex from the front and concave from behind. So their necks may have been flexible. They had long lightly built skulls with many relatively small teeth and they had proportionally small teeth. I was going to say their teeth didn't seem that small, but I guess for such a large animal, proportionally, they were small, not like t-rex teeth or, I guess, allosaurus teeth. Exactly. Just like when we talk about t-rex had proportionally small arms, but if you were to measure it on an absolute scale, it's still pretty big. Yeah. Like kind of size, all the most mega raptorans would put those arms to shame, for sure. True. And multiple mega raptor fossils have been found around the world. We may find more from lurasia in the future north, but we'll see, there's been a lot of debate over how mega raptorans are related to other therapods, part of their mystery. They evolved from being small in lurasia to being large and highly pneumatic in Gondwana. A 2025 study found that it appears that at least in central Patagonia, mega raptorids lived through a lot of climate changes and they successfully adapted, so it seems like they could thrive in a lot of different kinds of habitats. I guess that makes sense because they were found on pretty much every continent. That's a lot of habitats. Yeah. The hypothesis right now is that they moved from Australia to South America and then they got really big once they were in South America, not long after. They got their likely via Antarctica, sometime in the mid-Cretaceous. And then they seemed to have increased in size, going from like five meters long to seven meters long. So that's roughly 15 to 20 feet, I'm going to round two. That sounds roughly right. And they went from like 300 kilograms to a thousand kilograms. and weight. So like 600 to 2000 pounds. Yeah. Very roughly. Yeah, that's a pretty big increase. And then they stayed large. For example, mape is a very large one. I like mape. Yeah, it could get up to like 33 feet or 10 meters long. Then there's Baharia source, which is a potential possible mega-raptorine. That one is estimated to be up to 42 feet or almost 14 meters long. So yeah, mega-raptorine is like medium to large in size. That is bigger than I usually think about mega-raptorine being. So at least lengthwise, that largest one is pretty much T-rex size. And in just a moment, we'll get into mega-raptor, the dinosaur that started the whole clade, but first we're going to pause for a quick sponsor break. This episode is brought to you by Horde of Horns, this really cool new tabletop role-playing game where you lead a herd of serratopsids. We're so excited about this game. It was designed to be as scientifically accurate as possible by a pair of paleo nerds. All I had to read was in the FAQ where it said, where are the tyrannosaurs and try serratops? And the answer is, in geologic time, they will come later. Resisting the urge to put in just a big name dinosaurs that don't belong in the ecosystem is fantastic. This game takes place in the campaignian roughly 80 million years ago, which is perfect timing for serratopsians. The game includes eight serratopsids species, including centrosaurus, chasmosaurus, packurinosaurus, pentaseratops, regala serratops, spinoffs, styrakosaurus, and xenoseratops. Oh, all the ones with the best frills and horns. They are. You can see why they picked the campaignian. I didn't actually realize that centrosaurus and chasmosaurus were both in the campaignian until reading this list of serratopsids in the herd of horns description, so they taught me something to do. But it's not just a list of dinosaurs. This game looks really awesome. Yeah, we can't wait to play this game and we already backed it, so we're looking forward to trying it out. Yeah, they shared some of the book with us with some of the details about how the game works and it looks super fun. The kickstarter is ending very soon, so if you want a copy like we do, you should back it as soon as possible. Yes, and you can do that with our link I know dino.com/herdofhorns. You can also grab that link in our show notes. So that brings me to mega raptor, the arguable star of the show because that's where mega raptor I got its name. Yeah, you're not going to have mega raptor without mega raptor. Yeah, we did cover mega raptors our dinosaur of the day back in episode 216, but that was many, many years ago. Yep. So I wanted to devote some time in our mega mega raptor in episode to mega raptors specifically. That's a lot of mega raptors in one sentence. Yeah. What's the new research has come out since our dinosaur of the day? So mega raptor was a large therapist. It lived in the lake Cretaceous in what is now Argentina. It was found in the Portezuelo formation. It was about 30 feet or nine meters long and weighed about one ton. So on the larger size for mega raptorans, it had a long slender skull, at least in the juveniles. As an adult, it was probably a deeper, more robust skull, but we know the juvenile skull. It had long jaws. It had small conical teeth in the front of its jaws, and then more curved teeth in the back. So that gives it the heterodont teeth, different shaped teeth in the mouth. It had 10 cervical vertebrae or neck bones, and it had a wide, deep torso, the chest, the abdomen, the hips. It had very strong arms and long hands, and those hand claws were long and curved. It had three fingers on each hand, and the first finger, just like its relatives, was the longest and had the large claw. The third finger was the smallest. At times, mega raptor has been depicted as looking like a Dramayasaur, but it's not closely related to raptors, even though it's got the name raptor in the name. Trick-and-the-artists. The type and only species is mega raptor, Namun Huai Kyi. That genus name means "large thief," and the species name means "footlands" in Mapuche. It was named in 1998 by Fernando Inovas. He's the one who found the fossils in 1996, and at first only four bones were found, an arm bone, a long finger bone, part of a foot bone, and a huge claw. The claw looked a little bit like a Dramayasaur's foot claw, so originally, that's why the thinking was the claw was on the foot, instead of the hand. Those other bones, when compared to an Allosaurus, they were larger. They were larger than an Allosaurus's arm bone, foot bone, and finger bone, so for a while, mega raptor was thought to be larger than Allosaurus, and having this big killing claw on its feet. Like a hybrid Allosaurus raptor. Yeah, although some Allosaurus specimens could get bigger than the rough estimate for mega raptor, and four years later, a more complete skeleton was found, including a complete hand. And that's how he figured out that the foot claw was a hand claw. That's pretty handy. It didn't even mean to do that one. Now interestingly, Novas considered mega raptor to be a salurisaur related to either Dramayasaur's or Troodontids. So not exactly a raptor raptor, even though in the name. Now we know mega raptor from seven partial or fragmentary skeletons. Not too bad. Yeah. But only two of the individuals have parts of the skull. That is not great. Yes. The second specimen found included an arm bone and the complete hand, and it was found associated with a sauropod femur or thigh bone. The third specimen was a partial juvenile skeleton, although not everyone agrees that that belongs to mega raptor. It's hard to tell if the differences in features like the tail are because this animal was still growing, or if it's a different species. Juveniles are tricky. That they are. The fourth specimen found includes a humorous an arm bone. The fifth specimen has parts of the skull and a "large part" of the skeleton. But that one's only been described in a thesis, which also mentions two more specimens that include parts of the arm and a finger bone. So maybe one day it'll be even more described. We'll see. Mega raptor, of course, is known for its large claws. That first claw that was found was three times longer than a grizzly bear's claw. Moof. And that doesn't even include the tip of the claw. Oh, because that's just the bone part, not the keratin covering. Yes. So with just the bone, it's estimated to be about 14 inches or 37 centimeters long. But with the keratin, it probably was over 16 inches or 40 centimeters long. That is huge and terrifying. Yeah. That was one of the fun facts I really liked, including in our National Geographic Kids book. I know, I know. That was the exclamation mark. Yes. So at first, once scientists realized that Mega raptor had these huge hand claws, not foot claws, it was thought that it used its hand claws to rip open carcasses. But now it's considered to be a more active predator. It probably would have scavenged if there was an easy meal because what animal wouldn't, but maybe it also used its claws to grab prey and pull that prey closer to its jaws. A 2023 study found that Mega raptor could extend and bend its arms and could move its hands a lot, which probably would have helped with catching prey. Now, Mega raptor is closely related to Australoventador or how do you say, Gary, because I can't remember now. I used to say Australovenator. Yes. That's why I used to say it too. And now I can't go back. I just got used to saying Australoventador. Anyway, they're closely related and they had a lot of similarities. Australoventador had mobile arms and wrists and could possibly grip prey and then move it close to its jaws. So it could be that all Mega raptors did this. One study examined the brain case of the juvenile Mega raptor and then reconstructed soft tissues. So the brain, the blood vessels and more, the brain case is partially preserved. So that helps. And they compared it to morose raptor and other terapods. The brain case is highly pneumatized. A lot of air-filled spaces that seem to be one of the ways to just describe Mega raptor in general. Lots of air. Light weight. Yes. That's why it was only one ton despite being like the length of an Allosaurus. Yeah. And they found that Mega raptor may have had a mean range of hearing, somewhat similar to Velociraptor and the Therazinosaur falcareus. It also had a relatively large floccular lobe of the cerebellum. So they found that it probably had a stable gaze and then it could keep its head stable while moving its head rapidly. Good for hunting. Yes. Yeah. It would be better at pursuing prey compared to some other carnivores that lived around the same time like Abelosaurs and even morose raptor. Mega raptor had a small olfactory apparatus, so its sense of smell wasn't as good as Tyrannosaurus and Carcara dontosaurus, though. Now Mega raptor lived in a human climate with rivers or streams and other dinosaurs that lived around the same time and place include Abelosaurs, like Elmgasm, Titanosaurs, like Foot Alongosaurus and other terapods like Unilogia. Some other Other animals that lived around the same time and place include terrors, turtles, fish, and crocodile forms. Now that we've covered mega-raptor, I wanted to go into the rest of the mega-raptorans and just give a brief description of each because it turns out that we have covered most of these as our dinosaur of the day in various episodes. Yeah, a lot of them have been found fairly recently, right? Oh, yeah. So some of them are news items, too. But I will start with the unnamed ones. So there's an unnamed mega-raptor known as lightning law. It was found in Opal Fields near Lightning Ridge, Australia. I like lightning claw for that. Me, too. It lived in the early Cretaceous. It's estimated to be up to 20 feet or six meters long. That hand claw is about 10 inches or 25 centimeters long. And maybe it used it like a grappling hook to catch prey. When it was found, I think when it was found, as when they said, it was the largest therapist known from Australia, but I think that was before Australovendidar was found. Anyway, it was found by miners in Opal Fields, and they found a footballed parts of the hips, ribs, arm, and of course that giant hand claw, although it may be synonymous with rapidore. There were also two partial mega-raptor and skeletons described in 2020. These are from the Lake Cretaceous in Patagonia, Argentina, found in the Bajo-Bari-L formation. They're in two boot province. The fossils found include vertebrate, parts of the hips, parts of the hand, parts of the leg and feet. They also have large first fingers on their hands and other features that make them seem like their mega-raptorins. And they're likely at least seven meters long and weighed at least one metric ton. Now the oldest mega-raptored fossils have been found in Australia. These two individuals, again we're in Patagonia, Argentina, they're the oldest known mega-raptors from South America, or at least the oldest indisputable ones, by three or more million years. So that's why it seems that mega-raptorids started in Australia in the early Cretaceous and then moved to South America where they grew larger and eventually became apex predators. Now for the named mega-raptorins, we've got Fukui Raptor, which was our dinosaur of the day in episode 32. That's name means Fukui Thief. It lived in the early Cretaceous in Japan, and it was lightly built in Slender. The halotype is immature, but estimated to be like 14-ish feet or 4.3 meters long and weighed 1,300 pounds or 590 kilograms, and it had large flat hand claws. Then we've got Fukui Yung Venador that we talked about in episode 238. That's from the early Cretaceous in Thailand. Its name means Fukui Yung Thief and that refers to the Fukui Yung Mountains where it was found. Now, the oldest mega-raptorins that we know of are Fukui Yung Venador and value-raptor from Thailand. I should differentiate here, we've got mega-raptorah and then there's mega-raptorids. So earlier I was talking about the mega-raptorids that started in Australia and then moved to South America and then got really big. And this is a slightly broader group of mega-raptorah. Yes. The value-raptor, we talked about in episode 238, early Cretaceous Thailand again. The name means Win Thief and that was estimated to be like 13-15 feet or 4-4-1/2 meters long. So on the smaller side for mega-raptorah. So this might have been one of those many groups of dinosaurs that started out smaller and then got bigger. Oh, they definitely did. Yeah. I mean, mape. Yeah, that's true. And then there's Rapitar, we talked about in episode 91 from the Lake Cretaceous in Australia and it's fossil is opalized. We've got one left hand bone that was found in 1905. And again, lightning claw might be Rapitar. But I imagine it's hard to know for sure when all you have to compare is one hand. Yeah. But if you are going to have one bone, it's pretty cool if it's made out of opal. That's true. So getting more narrowly focused, we've got the mega-raptoriday. The group that's the closest to true mega-raptor itself. Yes. Well, it includes mega-raptor. But I'm going to go in alphabetical order. So we've got Arostion, which we talked about in episode 352. That genus name means airborne. Yeah. It's interesting. When I think of mega-raptor, I think hand claws, but I should also think about all these air bones. How lightweight they were. It's from the Lake Cretaceous in Argentina, and it's estimated to be about 25 feet or seven and a half meters long and weigh like one-ish short tones. Then we've got aiana raptor. But that's our bonus dinosaur of the day. So I'm not going to say anything about that one yet. And Australoventador, we talked about an episode 126, the southern hunter from the Lake Cretaceous in Australia. It's the largest known predatory dinosaur from Australia. It's estimated to be about 20 feet or six meters long and weigh like 680 to 1,100 pounds or 310 to 500 kilograms. So I'd say it's kind of small for a mega-raptor, but it's large for a carnivorous dinosaur in Australia, at least that we know of so far. Australia seems like there's a lot of discoveries happening. It's a little bit early days still for discoveries there, yeah. There was a 2024 study of how Australoventador went after prey that found that its claws were more for a hook and pull function, and they adapted to do that as mega-raptor evolved. So Australoventador may have gone after small animals or used its arms to go after larger prey by hooking the claws into the prey and then pulling them or tearing or slicing its flesh. Australoventador probably didn't have a high bite force. Even though it looks really cool. When I think of Australoventador, I just think of Banjo. Yeah, and the cool statue. Next up there is Joaquin Raptor, we talked about an episode 552, I think we called that one What Dinosaur's Eight, because that one was cool, it was found with a crocodile-form arm bone by its jaws with tooth marks on the bone. So it lived in the Lake Cretaceous in Argentina. It's estimated to be about 23 feet or 7 meters long and weigh over 2,200 pounds or 1,000 kilograms. Also known as a ton. Yeah. And it's very derived. It's one of the latest surviving mega-raptorons, it's from the latest of the Cretaceous. So it helps show that mega-raptorons were there until the end, until the bitter end. And it also helps with the hypothesis that mega-raptorids moved from Australia to South America and then got really big, because it was getting bigger and it's in South America. When we talked about it in the episode about What Dinosaur's Eight, we also mentioned how it's one of the most complete mega-raptor individuals found so far. And it was at least 19 years old when it died. So that 7-meter 23 foot length is probably around the maximum. Yeah. Well, it was maybe not full grown. Oh, really? Yeah. But maybe it was close. You'd think by 19 years old it would be. I don't know. There's a lot of debate over dinosaur growth. It's true. Yeah. It was cool because what keen raptor lived in this warm, humid flood plain environment close to the sea and it helped show that mega-raptorons could live in all sorts of habitats because other ones had been found in more semi-arid climates in the land. Mm-hmm. So next up, we've got MAPE. We talked about in episode 388. It's from the Lake Cretaceous in Argentina and it's the largest no mega-raptorid because I mentioned Bahariosaurus, but we don't know for sure if that's even a mega-raptora. But MAPE was about 30 feet or 9 meters long and weighed over 1.4 short tons. Pretty good size. Yeah. I like MAPE a lot. So I remember when it came out, or when it was first discovered, then of course there's mega-raptor, the large thief. That's what the name means. And MERS raptor talked about in episode 88, the wall thief. It was named in 2016, so that one must have been a news item. Yeah. It lived in the Lake Cretaceous in Argentina. It had a long snout and it's very pneumatic. An immature specimen was found, but it was larger and more grass-yled than mega-raptor specimens. It's estimated to be 21 feet or over 6 meters long, but again, that's based on the immature specimen. And it had fang-like teeth in the front of its jaw. Then we've got Orco raptor. We talked about an episode 489, the Toothed River thief, what the name means. That one lived in the Lake Cretaceous in Argentina and it's estimated to be about 28 feet or over 8 meters long and weigh 3,100 pounds or 1,400 kilograms. And the last of our mega-raptorids is Tratillenia, which we talked about in episode 175. This one lived in the Lake Cretaceous in Argentina and it's estimated to be about 26 feet or 8 meters long. There are likely mentioned before some uncertain or possible members of mega-raptora. And it turns out that we covered all but two of them in our episodes and one of them were covering in today's episode. Yeah, you've got Anisa Soros, that's the one we're talking about today. And I'll just list them without saying the episodes because if you want to look them up, the best way to deal it is to go to our website, I KnowDino.com and go to our episode list. But yeah, there's Bahariya Soros, Chalantai Soros, Da Tong Long. I will say we haven't covered that one yet. So maybe someone will request it. And there's Delta Dremayas, which we have covered, we've covered all the rest of them in this list. Io Taranis, Gualicio, Siatz. That's the North American one. Yes. Vectero Venador and Walgatosugas, which when I was looking at this list, I was surprised that some of them were considered possible mega-raptorids. Yeah, that's true. Yeah, like Gualiccio isn't that one more of a tyrannosaur? Could be. Well, depends who you ask. I guess so. When I, but I was thinking like, "Walgettosuchus," something was "Suchus" in the name, I think. Crocodile form. Mm-hmm, true. So yeah, that's mega-raptura. Before we get into our dinosaur of the day, I wanted to bring up a listener question. This one's not so much a question as a story that somebody shared with us. From mastodon, who says, "Yes, I know, that's not a dino." And they said, "Not a question, but I thought you might find this to be funny." A couple of years ago, my wife and I were at our son's house for dinner. We were sitting outside having wine and conversation while my five-year-old granddaughter was feeding mealworms to the chickens that they keep for egg production. Suddenly, their cat flushed a mouse out of the garden area. Before he could catch it, a hen rushed in, grabbed the mouse and swallowed it in one gulp. Oh, man. Upon seeing this, my wife, who's a city girl, let out a yelp and surprise. Without missing a beat, my granddaughter patted her on the shoulder and said, "It's okay, Baba. That's why chickens are really dinosaurs." I love everything about that story. Yes. It felt fitting to share in this episode, since we're talking about a carnivorous group of dinosaurs and how they potentially fed. Yes. That story is so good, because it's the five-year-old knowing and just completely not being surprised by a dinosaur-like chicken. Also, just that ferocious of a chicken. Oh, my gosh, yes. Because we know we have some friends who they dealt with rats, like basically killing off their chickens. It's funny to hear the chicken getting the upper hand. Yeah. I guess it can go both ways. And on that note, we're going to take a quick break for our sponsors, but stay tuned for our dinosaurs of the day. And now onto our dinosaurs of the day, because we have two of them. I'm going to start with the possible mega-raptor, keeping with our theme of mega-raptor, a nexusaurus. It was an avapod dinosaur that lived in the Lake Cretaceous in what is now Tribute Province in Argentina. So in other words, it's in the group that's closest to birds or close-ish to birds, maybe I should say. Yeah. If there are pods. It's interesting, because in some ways, it looked like allosaurus. It didn't have the crest on its head, but it walked on two legs. It had long arms, a long head, and a long tail. But it was small and robust. It's estimated to be like seven feet or two meters to 10 feet or three meters long and weigh up to between 77 to 99 pounds or 35 to 45 kilograms. That is small. Dog-sized, one might say. Oh, yeah, you could. The five individuals have been found and they range in age from juvenile to subadults. Its tibia was longer than its femur, so its shin bone was longer than the thigh bone, which likely means it was a fast runner. It was described in 2006 by Ruben Dario Martinez and Fernando Emilio Novus, Novus, who named mega-raptor. The halotype includes a right leg and foot, and the type and only species is an exosaurous Darwini. And that genus name means spring lizard, because it was found in the spring in the southern hemisphere, specifically September 21st, 1995. Ooh, the exact date. Yeah, that's over 30 years ago now. Ooh. The species named Darwini is an honor of Charles Darwin, who visited Patagonia sometime between 1832 to 1833. The details in its vertebrae, feet, legs, and hips are what make it unique, such as having deep neural arches on its neck bones. There's a lot of debate about how to classify this dinosaur, but a 2022 study found it to be a mega-raptor. It may have been gregarious, since five individuals were found in a bonebed together, and they know there are at least five individuals, because they found five right tibia. Mm-hmm. You only have one of those. Only one right leg per dinosaur. Yes. They were buried in a fluvial environment, a river or a stream. The skeletons were disarticulated from the currents and then buried. Mm-hmm. Making a trickier to piece together. Yes. That happens a lot in bone beds. True. There's no evidence of cannibalism or intra-species competition, which is why they thought the dinosaurs were gregarious. They all died together. But we've talked about on the show before, it's really hard to know from bone beds what kind of behavior the dinosaurs had. True. As we like to say, just because they died together doesn't mean they lived together. Mm-hmm. Yeah, because the fossilization is just one moment in time. Mm-hmm. And I guess in this case, we don't even know they died together. They could have just been squished together by the river. Oh, the thinking is that they did die together based on how they were buried and everything. One femur has small like three millimeter wide tooth marks, which is probably from a small scavenger. So it's possible they were just gathering at a water hole and they happen to be there at the same time, because we see this with some rhinos. Two of the individuals are estimated to be about three years old that's based on histology. And the three year olds died around the same time, which does make it seem more likely they were gregarious. Other therapists have been interpreted as being gregarious when they're found in bone beds, like celifices, a bird's-saurus, sign ornithamymus. Crocodilians, birds, and mammals are often gregarious too, and sometimes they're just gregarious at certain life stages, like earlier on. So maybe this dinosaur was gregarious or social as a sub-adult, like sticking together for protection or finding food together, and then maybe it became more solitary as an adult, we don't know. But it is fun to think about. Some other dinosaurs that lived around the same time and place include the ebela-saur, Xenotar-sosaurus. Saurapods such as Sarmientosaurus and Ornithopods, such as Notohypsilophadone. Then we've got our definite mega-raptorine. Our second dinosaur of the day, Aoniraptor. That was a mega-raptorine that lived in the early Cretaceous and what is now Argentina found in the Queen Cole formation. It likely looked like other mega-raptors. It walked on two legs. It had a long head and a long tail and long arms. So that's a decent size for a mega-raptorine. The type and only species is Aoniraptor Libertatum. It was named in 2016 by Mateus Mata and others. That genus name means south-thief. Aonir means south in Tehuilce. And then the species name Libertatum means freedom. And it refers to Aoniraptor being found on the bicentennial of Argentina's independence from Spain in 1810. The holotype is a partial skeleton and it includes tail bones and a sacral vertebra. It's a bone around the hips. The individual is probably not skeletally mature. It's based on neural arches not being fused to the center of the vertebrae. It basically comes down to some fusions of the bones. It's got a lot of similarities with delta-dramias and Baharia-saurus, which are both potentially mega-raptorines. So that's interesting because this one is definitely a mega-raptorine. It's vertebrae where long and highly pneumatic, which shouldn't surprise you if you've been listening to the rest of the episode. So there's a lot of air spaces in those bones. Even the hemal arches were pneumatic. That's the bones that attach to the bottom of the tail bones. Wow. Yeah, some scientists informally considered Aoniraptor to be synonymous with gualicio. That's a therapy pod found in the same formation because of similarities with their tail bones. And we were just saying how gualicio is a potential mega-raptorine. But a 2020 study found that there's a lot of differences between these two dinosaurs. Other dinosaurs that lived around the same time and place include the, well, of course, therapy pod, gualicio, the peravian overa-raptor, carcara-dontosaurus-like toravenedar, and titanosaurus-like chucarosaurus. Other animals that lived around the same time and place include some lizard-like reptiles and turtles. And last but not least, going back to our fun fact that we mentioned at the beginning of the episode, paleontologists originally considered mega-raptors' hand claw to be a giant foclo. And the opposite happened with Velociraptor. Because when Velociraptor was first discovered, scientists thought that its toe claw was a hand claw. Now we know where the claw is belong. And we know mega-raptor, despite having wrapped her in its name, was not a dremea sore raptor like Velociraptor. They're not that closely related. Yep. They're therapy pods, but other than that, I mean, I guess they're both avetherapods or, you know, in the more birdish realm of thetherapod family tree. Yeah. But not too close. Which maybe if you were to look at mega-raptor, you wouldn't think, that's like a bird. Yeah. But now knowing about all its airsacks, that's pretty bird-like. It is. Thank you for listening. We hope you enjoyed this mega-megaraptor episode. Stay tuned in our next episode of I Know Diana, which will come out in a couple weeks. We're gonna be talking about a bird that choked on rocks and dinosaur digestion. And we'll have some movie reviews. In the meantime, if you want your paleo fix, we will have a dino download about dinosaur brains and skulls. That's for our patrons. You can access that at patreon.com/inodino. Thanks again. And until next time. One last reminder that the Kickstarter "Herd of Horns" is ending very soon. It's a really cool new tabletop role-playing game where you lead a herd of serratopsids through all sorts of challenges. And you can be some of our favorite dinosaurs, like packy rhinosaurus, regalos serratops, styrakosaurus, and many more. It also features other cool dinosaurs from the campaignion, rivaling as well as trying to hunt your herd, which just sounds like so much fun. So if you wanna check it out, head over to our custom link at ino-dino.com/herdofhorns and back it as soon as possible so you don't miss out. You can also grab that link in the show notes.