The Mystery of the Megaraptors

dinosaurs are an incredibly diverse lineage of animals having existed for over 230 million years and adapting to film many different kinds of niches across our planet they made it through all sorts of mass extinction events even surviving today as the Ten Thousand living bird species currently inhabiting the Earth many Mysteries still remain when it comes to prehistoric dinosaurs though and a lot of debate and controversies surrounds various aspects of dinosaur paleobiology and evolutionary relationships one of the most interesting dinosaur Mysteries that still hasn't been entirely resolved is the issue of the megaraptors or more properly the megaraptorans a group of carnivorous theropods that lived during the Cretaceous Period this group of predatory dinosaurs were fairly diverse containing quite a few different species although the exact relationships between groups of megaraptorans and even which ones should be included as megaraptorans themselves are still debated these animals ranged in size from about 4 meters in length such as the relatively basal fukui Raptor that lived during the early Cretaceous in Japan all the way up to the massive and very recently described mipe macrothorax named in April of 2022 based on material from Argentina dating to the very end of the Cretaceous which is estimated to have reached about 9 or 10 meters in length one of the most notable features of these dinosaurs are the large and robust fall limbs with particularly big and fearsome looking claws on the ends of the inner two fingers of each hand and a much smaller Claw on the third digit in fact the heavily built arms and hands of these theropods were the subject of a recent study that aimed to reconstruct the musculature of the limbs in order to try and gain a clearer understanding of what exactly these animals were using them for when looking at the arm bones the paleontologists found that a lot of the muscle attachment sites seen on the fossils are notably well developed suggesting an important use of the arms and hands in the lives and paleobiology of the megaraptorans they even found that during the evolution of the group going for more basal members such as fukuri Raptor two derived forms particularly australianata from Australia and megaraptor itself from Argentina there was a notable increase in the size of these muscle attachment points so clearly they were becoming more specialized and more reliant on the use of their forelimbs the muscle attachment sites on the bones making up the pectoral girdle 2 show a similar enlargement and a trend to becoming more pronounced in later species looking at Australia Veneta in particular from the late Cretaceous of Queensland which is known from partial for limbs it's been established these dinosaurs were definitely up to something with their unusual Arms by creating digital models of the arm and hand bones in order to see how they connected to one another and how far they could move relative to each element paleontologists in 2015 discovered that australianata had an extraordinary range of motion for its arms and wrists as well as its fingers which bore the massive claws all of this evidence has therefore been taken to indicate that Mega raptorans were implying the use of these high highly flexible strong arms and hands that were capable of complex movements to capture their prey however the exact details of how they were doing this and the specific prey capture methods they had are yet to be fully understood whatever it was though it was definitely something interesting and seemingly very different to other groups of giant carnivorous theropods which mostly show a trend of decreasing arm size and more Reliance on their jaws made famous by the Tyrannosaurus megaraptor itself was first named back in 1998 and was subsequently classified in a variety of different positions among other theropod dinosaurs even as a spinosaur at one point the group technically called a clade known as megaraptora was actually only named in 2009 when paleontologists took a look at a grouping of carnivorous theropods called the allosauroids and attempted to resolve some of the classification issues with these animals the result of this study was that six problematic theropod taxa namely erosion australianata chilantisaurus for Curry Raptor megaraptor and orca Raptor were found to be relatives of a dinosaur found in England called neovenator neovanita is known to be a definite member of the allosauroids a large super family of carnivorous theropods including the famous Allosaurus and its relatives plus the carcarcharodontosaurs such as Acrocanthosaurus Giganotosaurus carcaradontosaurus and many others the researchers in 2009 therefore named two new clades of theropod dinosaurs to account for this newly found relationship the larger more inclusive grouping was named neovenatorade and included all of the six problematic taxa plus neovanator itself and then a more inclusive group within this one was named two comprising erostion australianata fukui Raptor Orca Raptor and megaraptor this clade was named megaraptora and for the first time the relationship between these mysterious dinosaurs was officially recognized this had some important implications for the evolution of the allosauroids too 2 as Orca raptor is known from fossils dating to the very end of the age of the dinosaurs so the inclusion of the species seemed to disprove the idea that allosauroids went extinct before the end of the Mesozoic Era but this is paleontology and specifically large carnivorous dinosaur paleontology so of course things were not going to remain quite so straightforward and controversy soon followed in 2013 a very different hypothesis of megaraptoran relationships was published paleontologists in Argentina performed a large review of Patagonian theropods from the Cretaceous finding some surprising evidence that supported the placement of the mega raptorans within the cellular Source another major clade of theropod dinosaurs including ornithomimosaurs of erepterosaurs theraxenosaurs dromosaurs Tyrannosaurs and the birds as well as others even more surprisingly the mega raptorans were found to be very close relatives of the Tyrannosaurus and it was argued that the anatomical characters of the bones previously used to show the they were allosauroids are actually quite problematic as these features are fairly widespread among many different lineages of theropods the paper also created a new family within the megaraptor and clade itself named megaraptoraday to include all of the species that come from the southern supercontinent of gondwana at the time of publication this included megaraptor erosion and orca Raptor from Argentina and australianata from Australia though others have since been named 2013 also saw the description of another large carnivorous dinosaur that has a problematic history of classification itself seats mikaorum seats comes from Utah and dates to the late Cretaceous Period about 98 million years ago when it was described in 2013 it was classified as a mega raptoran and mega Raptors were again considered to be included within Neo venatorade this was therefore reported as the first evidence of Mega raptorans being present in North America and seemed to show some interesting things about the patterns of how different lineages of large theropods replaced one another in North America before the Tyrannosaurs properly took over later in the Cretaceous we'll come back to seats again but in the time since it's been named it's been classified all over the place as an allosauroid some kind of celerosaur and as a tyrannosauroid then in 2014 researchers in Argentina published some more good evidence for a mega Raptor on Affinity with solorasaurs and specifically the tyrannosauroids again they described the partial skeleton of a juvenile megaraptor individual which preserved part of the skull of this animal and shows all sorts of features that are very similar to the Tyrant dinosaurs these features include very similar openings on the pre-maxor of the skull teeth at the front of the upper jaw with a d-shaped cross section and very similar structures on the roof of the skull in their evolutionary analysis of the position of megaraptors in the study the authors found strong support for them being nested deep within Tyrannosaur audio the super family of all Tyrannosaurs and the even recovered eotaranus from the Isle of Wight in the UK as a mega raptorin as well seemingly showing that these dinosaurs were also present in Europe although more recent Studies have since taken eoteranus out of the group moving forward to 2016 this year saw the description of another new Mega raptorum named Morris Raptor barosciences and coming from the late Cretaceous of Argentina the classification of megaraptorans was of course discussed in this paper and the two main competing hypotheses that their neovanitoroid allosauroids or that their tyrannosauroids were both considered but neither one was really committed to more than the other Morris Raptor was added to the known Argentinian radiation of megaraptorans though along with megaraptor erostion and orca Raptor 2016 also saw the description of yet another new Mega raptoron from you guessed it Argentina named aeoniraptor libertatum this dinosaur is represented by a series of fossilized vertebrae but they show enough similarities to other Mega raptorans to allow the classification of this dinosaur as such additionally it only Raptor shows more features with similarities to the anatomy of Tyrannosaurs especially in the tail vertebrae again providing support for megaraptors as a lineage of tyrannosauroids also in 2016 another very interesting and potentially quite important dinosaur was described that we also need to throw into the mix guelicho shinye was named from fossils found in unsurprisingly Argentina and is a fascinating example of apparent convergent evolution with the Tyrannosaurus since it possesses just two fingers on his hands with the third digit reduced to a splint just like in the Tyrant dinosaurs gueliche was class certified as a new venator red in its initial description and was found to be a close relative of the African Delta dromius however the evolutionary position of that dinosaur could be a whole other video on its own the paper also found Mega raptorans to be positioned back within new Aventura day as in those earlier studies since 2016 though guelicho has also been recovered as a cilerosaurin along with the mega raptorans 2016 was quite an action-packed year for megaraptor research as another paper published that year described some more Australian material from the early Cretaceous this specimen which comprises various fragments of the skeleton remains unnamed and is simply referred to by its accession number lrf 100-106 however it actually gives us some pretty important information about the origin of the mega rap Torrid family not only does this material represent the largest theropods so far identified in Australia but it shows that Australia was likely involved in formal interchanges between other gondwan and continents and the megaraptor self may actually have originated and first begun to radiate in Australia before spreading to South America Mega Raptor runs as a whole though were found to have first Arisen in Asia as indicated by fukui Raptor from Japan the most basal megaraptoran known at that point heading into 2018 the description of another megaraptoran named trattainia rosalezi was published and there are no prizes for guessing where this one was found it was Argentina trataunia was placed as another member of the more inclusive family of Southern mega raptorans mega rap toraday and found to be quite similar to other Argentinian Representatives but still distinct enough to be a new species trattayinha also turned out to be the largest carnivorous dinosaur in the particular geologic formation it was found in showing that after the extinction of the cockrodon Saurus here Mega raptorans were the ones to take over as the apex predators of South America interestingly though according to the phylogenetic analysis of the evolutionary relationships done in this paper Mega raptorans were positioned as an early branching lineage of silicosaurian dinosaurs but not as members of the tyrannosauroids supporting another third hypothesis of Mega raptorans as basal solarisons that are not included within the Tyrannosaurs and that brings us to 2019 when an interesting new Mega raptora named fuiang Veneta yay Nyomi was described this time actually from the early Cretaceous of Thailand this new species was found in to not be a member of the megaraptoraday family and was actually positioned as the most basal representative of megaraptora even more basal than the slightly younger fukuri Raptor from Japan this seems to show then that the megaraptors most likely first originated in Asia since the most basal species come from formations here another interesting conclusion drawn by the paleontologists on this paper is that the mega raptorans seem to have become fairly geographically widespread early on in their evolution with slightly younger but still early Cretaceous aged megaraptorans known from Australia as well as South America however the megaraptorans then became highly provincial later on in the Cretaceous with the majority known from South America in terms of megaraptorin classification the controversy was once again discussed in the paper naming furiang venator and the clade was recovered as belonging to silerosoria but not being especially closely related to the Tyrannosaurs then we come to 2022 when a very exciting paper was published describing the largest known Mega raptoron found to date the enormous mipe macro thorax from the very latest Cretaceous of Argentina maibe comes from a formation dating to the final stage of the Cretaceous Period and is so far the only relatively complete megaraptoran from this time it again groups with the other previously named South American megaraptorids and some key anatomical differences with the mega raptorans known from Asia and Australia were also identified such as the South American forms being much larger in overall body size and far more robust in their proportions MIP itself is particularly notable for its very wide chest measuring about 1.2 meters across and giving the species a particularly bulky appearance for a megaraptor the animal likely measured about 10 meters long and it seems the reason the species was able to grow to such a large size was due to the extinction of the cochradontosaurus dinosaurs in South America near the start of the late Cretaceous the lineage of theropods including Giganotosaurus mapusaurus and others the Spinosaurus also went extinct at a similar time too with those other giant terrestrial carnivores out of the way South America the very end of the Cretaceous seems to have become the land of the mega Raptors with these dinosaurs growing to ever increasing sizes and taking advantage of those newly opened niches the major radiation of megaraptor and diversity in South America also appears to have coincided with the extinction of those other theropods too providing more evidence to explain the success of the megaraptors around this time the paper naming map also managed to better refine some of the internal relationships within megaraptora as well the Asian and Australian representatives were again shown to be the more basal members leading up to the more derived South American clade within the South American clades though a more inclusive clade called clade a was defined that includes megaraptor Morris Raptor and the less inclusive clade B which contains Orca Raptor trattainia erostion and maip the signif significance of these two South American groupings is that they appear to reinforce the timings of the megaraptored radiation with megaraptor and Morris Raptor coming from earlier in the Cretaceous and reaching generally smaller sizes compared to the members of clade B which lived later and grew even bigger but what about the paper's findings on where megaraptor and sit among other theropods well the authors once again support a position as silicosaurians but instead of being placed within tyrannosauroidia they found megaraptorans to be the Sister Clay to them meaning they are each other's closest relatives so the paper concludes that unlike the situation at the end of the Cretaceous in North America where the tyrannosaurids took over the apex predator Niche after the cochradontosaurus Disappeared in South America it was the Mega Raptors that occupied these terrific positions alongside a diverse lineup of other theropods such as the abelisaurids famously including Carnotaurus and the unin logians such as Ostro Raptor and that leads us to another fairly recent and interesting development in the mega raptoron story when in 2022 an extensive and very detailed study on the early Cretaceous age tyrannosauroid eotaranus from the Isle of Wight in England was published This research thoroughly described All the known material for this dinosaur and then also investigated its Evolution relationships among theropods finding some significant support for the megaraptorans to again be included within the Tyrannosaurus super family it supports the mega raptorans as being a second wave of large-bodied tyrannosauroids that evolved towards the end of the early Cretaceous and even suggests that the arrival of this lineage may have actually delayed the radiation of the Tyrannosaurus the group leading two T-Rex itself this is because siat which we met earlier was again found to be a basal member of the megaraptorans so it potentially represents a lineage of megaraptorans that invaded North America and ended up suppressing the rise of the Tyrannosaurus until much later the previous interpretation of eotaranus as a megaraptor that was made in 2014 and which I mentioned earlier was not supported by the study however eotaranis therefore is positioned as a more basically branching tyrannosauroid with mega raptorans splitting off later the placement of megaraptorans as a branch of tyrannosaurus which seems to be better and better supported every year has many fascinating implications for the evolution of one of the most famous dinosaur lineages not only did they potentially have a major influence on the evolution of later tyrannosaurids but it's very interesting that the megaraptorans seem to have evolved more specializations for pre-capture and manipulation with their forelimbs whereas the Tyrannosaurus went down a very different route undergoing a trend towards smaller for Limbs and prioritizing prey capture with their robust Jaws so there we have an overview of the megaraptorans and the recent history of study on this fascinating group of theropods obviously this is still a changing and very fluid subject and I'm certain more studies will be coming out soon that make parts of this video outdated but this is our understanding of these dinosaurs so far it's amazing how much our understanding of this pretty significant lineage of dinosaurs has changed over the last decade or so and to think of these dinosaurs as another branch of tyrannosauroids is honestly pretty exciting showing that these dinosaurs led to not just one but two separate lineages of apex predators I really cannot wait to see what other discoveries are made about the mega raptorans and what new species must be out there for us to find anyway thank you for watching and a big thank you to our patreon supporters especially our dinosaur tier supporters Amanda Von nordek archieanthus Clara Middleton Daniel Ingraham drove srivastava Gary Arrington giotist Greg Silvernail Corey Peterson loxypoo Mark Nevin mendicant Friar Mike Pace monitor man Persian Boy Ralph Balzac Robert Thomas and Steve Bradshaw if you would like to find out more 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Channel: Ben G Thomas

Views: 634,120

Keywords: Biology, Science, Paleontology, Palaeontology, Dinosaurs, Animals, Nature, Wildlife, Ben, Thomas, Prehistory, Anatomy, Fossil, Bones, News, 7Daysofscience, Days, of

Id: Xmg4yhkZLwQ

Length: 19min 11sec (1151 seconds)

Published: Sun Aug 13 2023