REFERENCES Eagle behavior: cbop.audubon.org/conservation/bald-eagle-biology#:~:text=Territorial%20Fights%3A%20Although%20eagles%20are,eagles%20throughout%20the%20nesting%20season. Additional eagle behavior: pages.vassar.edu/sensoryecology/bald-eagle-haliaeetus-leucocephalus-general-biology/ Nile crocodile behavior: www.sciencedirect.com/science/article/pii/S2351989421002936#:~:text=Socially%2C%20crocodiles%20are%20gregarious%20and,Crocodile%20Specialist%20Group%2C%202009). Tyrannosaur pack footprints: www.theguardian.com/science/2014/jul/23/tyrannosaurs-hunted-packs-tracks-canada Collaborative hunting in crocodilians: www.researchgate.net/publication/272369202_Apparent_coordination_and_collaboration_in_cooperatively_hunting_crocodilians Albertosaurus mass mortality: pubs.geoscienceworld.org/cjes/article-abstract/47/9/1119/344288/Stratigraphy-sedimentology-and-taphonomy-of-the?redirectedFrom=fulltext Teratophoneus mass mortality: peerj.com/articles/11013/ Daspletosaurus bonebed: scholar.google.com/scholar_lookup?title=An%20unusual%20multi-individual%20tyrannosaurid%20bonebed%20in%20the%20Two%20Medicine%20Formation%20(Late%20Cretaceous,%20Campanian)%20of%20Montana%20(USA)&author=Currie&publication_year=2005 Sue was a part of a nightmare of Tyrannosaurus: www.amazon.com/Tyrannosaurus-Tyrant-King-Life-Past/dp/0253350875 (Page 20). Peter Larson personal communication; Bucky Derflinger personal communication. Triceratops herd behavior: www.naturalis.nl/en/about-us/media/press-releases/triceratops-teamed-up-research-shows-that-five-three-horned-dinosaurs Crocodiles working together to take down a rhino: Guggisberg, C.A.W. (1972). Crocodiles: Their Natural History, Folklore, and Conservation. David & Charles. p. 195. ISBN 978-0-7153-5272-4.
You forgot to Mention the Tailes rex specimen. While not Direct evidence, its injuries would have prevented it from Hunting for several months and it would have died if not helped by a mate or Packmate. To me its not a display of true pack Behavior, but i believe that Theropods in general would act more like their descendants and live in monogamous pairs that would protect their young before they would be chased off before their sexual maturity.They wouldnt hunt for them but allow them to roam their territories and feed on the Smaller preys and smaller carnivores, taking out any treath to younger broods.
Accurate in terms of crocodylians being a reasonable point of comparison. And Tyrannosaurus rex did have one of the largest brain to bodymass ratios amongst dinosaurs (only a handful of maniraptorans score better), but it is still within the range of modern reptiles, yet below the range of all but the relatively-smallest-brained birds. The structure of its skull also resembles modern crocodylians a lot more than it does resemble modern birds. Now, cooperative behaviour is at best... let's say, loosely tied to intelligence (the most drastic example are multicellular organisms, or if one wants to one-up that, siphonophorae; literally brainless organisms cooperating to the point of forming complex bodies and adopting specialised roles), and Tyrannosaurus' habit as a terrestrial predator (exact means of predation debatable, but I personally lean towards it being a pursuit predator, courtesy of its immense size and the excellent eyesight of diapsids making hiding difficult, plus the moderately ectothermic tendencies of its prey making pursuit a fairly favourable proposition) being rather distinct from that of crocodylians also makes behavioural inferences from this comparison problematic at best. To be clear, nothing that you wrote was wrong, and nothing I wrote disagrees with what you said. I just feel like heading off the usual swerving into bird intelligence (and to be clear, the average bird is not a corvid or psittacine...), which just... doesn't apply to anything except some maniraptorans. And actual birds. Sources: Relative size of brain and cerebrum in Tyrannosaurus rex: an analysis using brain-endocast quantitative relationships in extantanalysis using brain-endocast quantitative relationships in extant alligators, by Grant R. Hurlburt et al (available as .pdf) Fossil biomolecules reveal an avian metabolism in the ancestral dinosaur, by Jasmina Wiemann et al (paywalled)
@@Manny4Life948 I haven't seen any of the studies specific to their skulls (they exist, but I haven't looked at them yet). The second of the two abovementioned studies suggests that most ornithischians were secondarily ectothermic (similar to crocodiles, who have adaptations suggesting an endothermic past, but apparently lost this at some point; worth noting that the ornithischian breathing apparatus may have been somewhat comparable to crocodylians, on this, see 'A new Heterodontosaurus specimen elucidates the unique ventilatory macroevolution of ornithischian dinosaurs' by Viktor J Radermacher et al; note also the distinct lack of evidence for air sacks in ornithischians), and said study explicitly argues for this implying an order of magnitude lower neuron density, but 1. some hadrosaurs cross the boundary to 'Maybe endothermic' in terms of the analysed isotope patterns in said study 2. that's specific to this isotope study. Growth patterns for hadrosaurs suggest a more endothermic physiology 3. while there is a tendency towards endothermic animals being brighter than ectothermic ones, this is not an absolute. Off the top of my head, varanids, crocodylians, cartilaginous fish, some hymenopterans and some spiders have all demonstrated considerable intelligence, and they're certainly not endothermic Given hadrosaurs' efficient metabolisms (chewing) and the evidence of parental care, I cannot imagine them being particularly lacking in the intelligence department. Loosely around modern crocodylians would be my guess. A smidge behind Tyrannosaurus. But again, that's without actually having looked at the studies of their skulls.
"What could be worse than a 40 foot long predator with the strongest terrestrial bite force?" "Oh I know! Two (or more) 40 foot long predators with the strongest terrestrial bite force!"
"Nightmare" is the perfect collective for Tyrannosaurus. A gaggle of geese, a murder of crows, a blessing of narwhals...a _nightmare of Tyrannosaurus._
not an expert but nobody brings up that no modern reptiles have the same niches as dromaeosaurs (larger ones) so maybe we should base them partily on wolves/cats..?
@@playernotfound9489 yeah, these animals probably needed more territory because they need way, way, way more energy than especially crocodiles and alligators do, so if they were gregarious, definitely not in the same manners as crocodiles and such. Personally, I think that the difference there is so great that if they're found in groups, they're either fighting, mating, or hunting. They're not amphibious either, so while they'd need to get water, they wouldn't all have to slide in every once in a while nor do we think they needed to bask. So, essentially, all the things that drive crocodilian gregariousness in the way that it is do not apply at all to Tyrannosaurs. Cats and birds of prey can tell us things, I think we agree. I think crocodilians do the opposite and essentially show that some coincidences are unlikely, so if we find them together, it's better proof.
New evidence: Trexes would congregate together once in a blue moon to do a "fusion dance" to form a super predator now known as Titanus Gojira Rex in order to hunt bigger prey such as Alamosaurus. In a more serious note, this is mind blowing. A 10 ton predator working possibly working in groups? I'm excited to see some more material about this! I wish we could actually see breathing and living Rexes (from a safe distance) and watch them do their thing.
I have heard rexes only got massive once they reached a certain age. They spent most of their lives as subadults, being vassal predators to the fully grown adults. To me, it would make sense that once they are abandoned by their parents, siblings would likely have stuck together for protection, slowly becoming more solitary as they grow and thus required more calories. An adult rex would have needed to eat a lot of meat to sustained itself, so sharing probably wasn't common outside of especially large prey or a parent with offspring. Not to say they were on their own once they reached 6+ tons, but it seems reasonable that the younger rexes would be more social than adults due to their smaller size and lower caloric intake.
Great video! And thank you for FINALLY pointing out that intraspecific combat (or even cannibalism) by no means rules out gregariousness and even social behavior. On Sue being found with other juveniles, I actually messaged Thomas Holtz JR about it months ago. He pointed out that those other specimens, while coming from the same Quarry, seem to come from different stratigraphic levels. Died at the same place, but not at the same time. I'd like to see other experts's take on that. That said, I do personally believe T. rex was indeed social, and I often portray it in my artwork as monogamous (for life or seasonally) and caring for it's young for the first few years of their lives. Great to have a video laying out the potential evidence from related taxa as well! Keep up the great work!
I appreciate your comment! I spoke with Pete Larson about it, since he and Neal were the ones leading the dig, and he specified that the bones were buried together in a pile. You can even see in some of the pictures that the lacrimal was inside one of Sue's fenestra. Your artwork sounds awesome! Do you have a link?
I have pictured the same thing about adult tyrannosaur behavior too, but when it comes to the juveniles I think they stay with their parents until they are eleven to twelve years old and strike off on their own and then meet other juveniles and form coalitions with them.
I love hearing people open up with “I was wrong” so much. It’s not that I like people being wrong. I’m pretty ambivalent about that. It’s just that people who are willing to admit their mistakes and correct the record are very rare today.
Sue was already 30 years old when she died, I’m more scared on what killed Scotty (aside from disease) as he was slightly larger or same size but much younger (23-27 years)
You forgot about Yutyrannus and, if I remember correctly, Guanlong being found in groups when first found. Also, Stan, Duffy, and Stephinie (formerly Steven before eggshell fragments were found) were found fairly close together.
That's true! Yutyrannus and Guanlong were relatively distantly related, but it's still a valid point. Apparently there may have also been some grouping with some of the LACM Tyrannosaurus specimens, but it's hard to verify that they were buried in the same event unless it's something like what I covered here with Sue.
It’s definitely an interesting debate I personally believe that using modern archosaurs as a comparison is a bit of fallacy when it comes to certain behaviors like pack hunting as Non Avian Dinosaurs took up very different ecological roles from modern archosaurs like crocodiles and avian dinosaurs.
Modern archosaurs are far from a perfect analogy, for sure. More closely related taxa are better comparisons, and it's even better to find things like this!
Ikr, especially when you realize that Crocodilians & Birds of various groups were around at the time and were most likely maintaining the same niches as today, including Avisaurus which is believed to have lived a lifestyle similar to modern day birds of prey and there were even Ratites related to Ostriches & Emus that were around as well, a lot of people don’t realize that birds were already quite diverse in the Cretaceous period, so maybe it wouldn’t be too far fetched to assume that the ecological niches that non avian dinosaurs maintained in their ecosystems would’ve been very similar to mammals despite the fact that they’re not closely related, they could’ve easily taken up the same niches that medium to large sized mammals take up today and even certain small mammals in the case of Alvarezsaurids, and they could’ve even been similar as far as behavior is concerned, because sometimes certain niches can correlate to certain behaviors.
T.rex is already overpowered enough, but God decided that it needed another buff. One Rex by itself is already a nightmare, but several… I would start praying Mr. Alamosaurus
The most Dinosaur resembling creature that I can think of is the Cassowary. If you squint just a smidge you can just make out a Dromaeosaur. Observing the Cassowary's environment should give a good analogy for Therapod behavior.
Seeing one T.rex in the wild would be dangerous, but a family or a mob of these dangerous creatures would be a nightmare. It’s interesting that both prehistoric planet and ironically Jurassic Park lost world both depicted the T. rex as either a solitary, family hunting and strong paternal care for their young. Even the males in both programs were shown to either help with the young or actually care for them. Hell the buck rex from lost world cause a lot of damage to get his son back.
Fun Fact: Tigers the big cats we often stereotype was loners have been recorded hunting in pairs & even groups up to 4-5 to bring down large prey in regions of Nepal & India...
Personally i believe the evidence for complex socialising and pack hunting is nigh nonexistent. It seems like tyrannosaur adults are frequently found with juveniles, suggesting parental care, but not that they stuck together after that, and certainly not that they hunted together. Until inarguably disproven, I believe in the statistical fact that complex pack hunting is incredibly rare throughout the animal kingdom. It should always be viewed as an exception and never be assurmed without strong direct evidence.
I firmly think that, like hawks and eagles, Tyrannosaurus Rex absolutely mated for life. Most especially since Celurosaurids like Rex were on a much higher intellectual spectrum than say, a carnosaurian predator like Allosaurus and Giganotosaurus. Even though they were bigger than elephants, Tyrannosaurus is STILL a close relative of birds and most likely exhibited much of the same behaviors. And it makes sense given the extraordinarily dangerous world they lived in.
I'd say that while Tyrannosaurus hunted alone more often than not, it was probably smart enough to assess that in some situations it was equally beneficial to work with another Rex or so. Similar to how Eagles make temporary groups with infighting from time to time, while also being able to coordinate with strangers similar to crocodiles.
Also haven't Crocodiles been shown to use bait to grab birds, I have seen a few videos where they use branches to trick birds onto getting them for nests before the Croc takes the bird..
Good job. You helped me change my perspective on Tyrannosaurus Rex pack hunting. I've seen Sue many, many, many times and seeing more discoveries related to "Sue" makes me just love them more. A gregarious lifestyle makes more sence to me. I personally think that Tyrannosaurus Rex would have only pack hunted with young with their young was old enough, yet, they would still ambush their prey. Tyrannosaurus Rex migth have hunted in packs in other instances but since theres not much evidence we really have to create our own theories. Finally, what are your opinions on "Ivan" and "Bertha"the Tyrannosaurs. Those are just my personal thoughts and opinions. Amazing job.
I like this hypothesis too, it would explain the difference in morphs between the specimens so far, which is interesting because I would have guessed the opposite with the bulkier ones being specialized in ceratopsians and not hadrosaurs
@@Charlie-Charlot perhaps the more gracile and smaller tyrannosaurs are smaller due to being stunted because of how difficult Triceratops are to take down? as an AVID trike fa i sure as hell hope it aint bc trikes are fodder lmao
@@IndominusRex-wc1ey I’m quite convinced these horned tanks were definitely not fodder lmao, it is just kind of counterintuitive to imagine the less robust specimens being more adapted to hunt trikes although it could explain a certain disproportion of smaller specimens to die due to these confrontations and fossilize afterwards Man these rexes keep getting more fascinating every time
so they were social animals. I wouldn't be surprised if they hunted together to take down a larger dino and then shared the meal. and one thing to notice is that even today. A lost of highly intelligent animals tend to stick together> Chimps, Orcas, elephants, lions, crows, parrots ETC and sense trex was a highly intelligent animal. I would assume that it did the same, not to the same degree as primates or other animals but still very affective
I often wonder if Rex benefited from interspecies sparring and competition similar to lions where they can learn basic combat and hunting techniques from their siblings and older relatives
Came upon this on my recommended and was pleasantly surprised to hear the speculative rex sounds I created for the channel intro! Really sick video. The thought that predators as big as rexes couldve planned hunting together or been social is just crazy to think about. If you ever need more dinosaur art/graphics I’m also a paleoartist and would love to work on something like this or make more sounds, feel free to reach out! :)
Hello, and thank you for your comment! I definitely will--I loved the sounds that you created. I remember reaching out about using it as an intro last year and I'm glad that you like how it was used! Do you have a Deviantart?
I'd also like to mention a lot of the push for mobbing rather than actual coordinated hunting is based on intelligence. That's what the paper on Deinonychus used, that reptiles aren't intelligent enough to work together. Tyrannosaurs seem to be on the upper end of dinosaur intelligence, and at the very least needed brains that could process all the information from their absurd senses, so I don't quite think that goes against them being potentially social. I've also read that crocodiles will work together when subduing extra large prey, like a trio of crocs that actively worked together to bring down a female black rhino.
@@TheVividen I found the description here en.m.wikipedia.org/wiki/Dietary_biology_of_the_Nile_crocodile With citations from [2] Guggisberg, C.A.W. (1972). Crocodiles: Their Natural History, Folklore, and Conservation. David & Charles. p. 195. ISBN 978-0-7153-5272-4. And [72] Selous, F. C. (1908). African nature notes and reminiscences. Galago.
T. Rex was certainly quite intelligent. We can't really know if it's brain was more akin to an avian brain or a non-avian reptile brain. This does make a huge difference with regards to its actual intelligence. Even with a reptilian brain, though, pack hunting is not out of the question. Tegus and monitor lizards don't hunt in packs, but they are more intelligent than most people think, and have been described as being dog-like in their behavior. That crocodile group hunting would also be good evidence of pack hunting in non-avian reptiles. T. Rex had, to my knowledge, a higher EQ than any of those (though that metric certainly has its flaws). In fact, its EQ was on par with chimps. Even with a reptilian brain that has the potential to make it a lot smarter than people think, and with an avian brain it would be probably even smarter than most primates. Keep in mind that birds have a higher neuronal density than mammals, so even if T. Rex had a neuronal density a little lower than birds, it still might be as smart as some of the most intelligent animals alive today.
@@TheWigglergler Even with the statements after that it was "a chimp compared to reptiles" like mentioned crocodiles can and do have the capacity to cooperate with others. This is even true in feeding which is more commonly filmed. Groups of crocodiles taking turns to feed on say a hippo carcass. That shows crocs can understand their own self, what another is doing and to hold back rather than just all chomping down at once. One could imagine T.rex or mcraensis doing that with a fallen titanosaur. Indeed, the first papers refuting dino group behavior used Komodo Dragons as their evidence at how uncoordinated and lacking in brains reptiles were perceived. But like you said they can be quite cunning.
I would be very interested if you made another video about the potential social behaviors of carcharodontosaurids as well since Mapusaurus was also found in a group of individuals of various ages preserved together.
I would agree that theropod dinosaurs would hunt in gangs not pack hunting. I don’t think they would not live together and I’m pretty sure that when they kill something they would probably fight over it a lot and that’s why you see bite marks on some specimens and I didn’t know that Sue Was with other tyrannosaurs. Maybe it’s a possible chance that Sue was probably the dominant one and chased after the others to claim the carcass while the smaller individuals lay back and wait their turn to eat the carcass, but then again, there was no dead triceratops or no dead hadrosaur but I’m just saying a hypothetical scenario, and yea Tyrannosaurus rex’s brain was more that of a crocodile than a bird, even though bag that I used to think that M would’ve hunted in pairs like eagles, but that’s not really the case but who knows
This information has a secondary implication - that Nanoturannus is its own genus. I had the opportunity to speak with Dr. Larson at the Black Hills institute, and I got to see the mandible of one of the baby rexes discovered alongside Sue… teeth were shaped exactly like an adult Rex’s, and nothing like the blaze like teeth on a Nano. Anyway, there’s my two cents.
I can only think of two pack hunting dinosaurs Yutyrannus and albertosaurus both of these are relatives of t rex though one is a tyrannosauroid who has fully functioning arms and 3 claws My ideas for naming a group of prehistoric animals A group of triceratops and torosaurus is a crash A group of yutyrannus is a floof a floof of yutyrannus A group of pterosaurs is a band A group of hadrosaurs is a flock cuz yes A group of albertosaurus is a mob A group of spinosaurids is a net a net of spinos A group of dromaeosaurids is a coalition A group of pachyrhinosaurus is called a mob boss A group of shunosaurus is a smack A group of every other sauropod is called a boom A group of deinocherius is called a Quack Ok last one a group of therizinosaurids is called a slap
Paleontologist: "You are no pack. You are..." Tyrannosaurus Rex: "A nightmare. And I don't mean it metaphorically or rhetorically or poetically or theoretically or any other fancy way. I'M A NIGHTMARE". Reference to Puss In Boots: The Last Wish.
Sue was found with TWO juveniles? I heard about her being discovered with multiple other T-Rexes, but what I heard was that of the two youngest, one was a juvenile with an 18-inch skull, and the other was a BABY with only a 10-inch skull.
Solid video! Only parts that are a bit off is "There are no birds around today that fill the apex predator niche" The narrator does correct this by bring up Eagles. Eagles are considered apex predators. The other is thinking crocodiles are a closer analog for T.rex than birds. T.rex is part of the Coelurosaur family which are all dinosaurs closer to birds than crocodiles. If we were talking Allosaurus, Torvosaurus, Carcharodontosaurus or other dinosaurs of the sort then crocodiles would be a better analog than a bird. Allosaurus actually has a brain similar to that of a crocodile which we know from CT scans. The Albertosaurus group sight did have juveniles indicating some sort of family group. It would make sense for a T.rex to hunt in groups to take down a Triceratops. One on one the Triceratops is going to win regularly. But two adult T.rex against one Triceratops? That Triceratops will make a nice buffet for the Rex pair. Pack hunting would work for Edmontosaurus, though ambushing or taking on the young would also be sufficient. Now that I think of it, T.rex would probably need to reach a certain size before it would stand a good chance of killing an adult Triceratops with or without backup.
On the topic of fossil remains of other Tyrannosaurids found in groups, Phil Currie has mentioned yet to be described fossil finds of Tarbosaurus in groups. Which is what might have given the Prehistoric Planet team the justification for their pack living Tarbosaurus.
With this being posted on the 30th of March, I almost worried it was supposed to be an April Fool's joke. But man I'd love to hear more about the other specimens found with Sue. I actually messaged the Field Museum just now about this.
@@TheVividen "Hi Preston, Thanks for your email. The other Tyrannosaurus specimens found with SUE are all isolated, often incomplete bones. There are isolated bones from other dinosaurs, too. The only other dinosaur found at the SUE site which was more than an isolated bone is a skeleton of a pachycephalosaur. The isolated bones from various dinosaurs were probably washed into the site by the flood which buried SUE. Best, (His name)"
Now I did hear Sue was found with other rex's and I think the reason nobody has gone back is because they don't trust the rancher. Sue has been studied inside and out and there is no evidence to support that she was killed by another Rex.
I personally am not super convinced by the idea of Sue getting killed by another rex, but I do know that there was quite a bit of controversy around the original finding that may discourage further research. Sadly...
@@TheVividenThere is a study (or at least a preprint) of a reanalysis of the holes in Sue's jaw. The researchers are part of the study concluded that they are bite marks, and not caused by parasitic infection as previously thought.
If we discover more sites with a large adult or two in close proximity to smaller and younger individuals then perhaps Tyrannosaurus living in family groups could be opened for debate. Young and Juvenile rexes stuck with one or both of their parents for quite awhile before becoming and adult and going off on their own.
This video is awfully quiet, FYI. Also, let's not forget that Sue is the only T-rex observed eating humans. Admittedly, she was chomping down on zombies, and was herself a zombie at the time, and the whole thing was written off as a mass hallucination and a college prank.
@@TheVividen Thanks! Loved the video btw, found it really fascinating how evidence suggests that megatheropod pack hunting slowly started to focus on smaller prey, from sauropods to hadrosaurs
One thing nobody points out is that while tyrannosaurus is large, so was its prey. And not only that, herbivores like the triceratops were far more dangerous than people give them credit for. I think it would be difficult for even a single Rex to hunt a herd of trikes but not impossible. It is also difficult to judge an animals social hierarchy based on their fossil record. Even the fossilization process would be difficult, there are probably more fossils that didn’t get preserved.
5:02 Wait, oh my gosh. In the abomination of a documentary Jurassic Fight Club, I distinctly remember a dumb scenario where a Nanotyrannus was fighting some young T-rexes along with their mother which came in later. So... JFC actually somehow contributed to science by depicting that fossil find with Sue?
I think some type of 'cooperation' is likely, if, as a recent paper proposes, larger Rexes would not have been able to run. Therefore they may have relied on younger Rexes driving or killing game, that the larger ones would then steal and eat.
Hi Vividen. I enjoy the content. With that said . . . On gregariousness in bald eagles. You can find video on YT where fishermen are surrounded by bald eagles--dozens at a time, being thrown bycatch fish. Similarly, in Unalaska, a woman named Pam Aus took videos of her housecats and their friends--visiting bald eagles and wild foxes. These normally hostile predators were perfectly comfortable in each others' company. My point? Wherever food is plentiful, more complex sociality is not only possible, but permissible. Thanks for taking time to consider this. Here's a video from Dutch Harbor on eagles losing inhibitions due to plentiful food: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-y0pOndzESnY.html Here's video shot from Pam's front porch: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-AI2dtKxxuYc.html
8:20 turtle remains? I've always felt that a Rex would be ideally suited for feeding on sea turtles during the breeding season--sea turtles were particularly vulnerable when crawling ashore to lay eggs, and Rex teeth and jaws would probably have no problem crushing turtle shells==I even imagined Rexes would gather at beaches like Kodiaks waiting for the salmon runs. Naturally these are seasonal opportunities--they could pursue other prey at other times of the year (hatching season would be a great feed for younger Rexes or other tyrannosaurids/oids); That assumes that the sea turtles who lived in the Western Interior Seaway weren't all armored giants like archelon (though, given the predators that DID live in the sea, would probably mean sea turtles had to be built like the proverbial brick house)
it takes a long time and a lot of failed lives for T Rex to get to it's maximum size so when it finds another one of it's max size why wouldn't they group up? Over 9000 Rexes together are better than 1
