What Was the Biggest Dinosaur? - Part 1

dinosaurs are famous the world over for being big and for being dead but as our understanding of these animals developed over the decades and even centuries since they were first discovered it's become more clear that this isn't exactly true firstly dinosaurs are not dead as an incredibly successful lineage of theropods survives to the modern day the birds and secondly not all dinosaurs were big but of course some of them were some of them were really really big the largest land animals to ever walk on our planet in fact ever since the biggest of the dinosaurs the sauropods were first recognized for what they were people have been asking which one was the largest of them all various different contenders have been proposed at different times but this is far from a simple question as problems of incomplete fossil records for these giants differences in how various weight estimation methods work and other issues have led to a great deal of controversy over the most gigantic dinosaurs i recently had to answer this very same question for an assignment for university and so i thought it would be fun to repurpose the research i did and expand upon it for a video so then what was the largest dinosaur well a pretty solid contender for this title is the titanosaurus species argentinosaurus huinkolensis the remains of this sauropod were first uncovered in the late 80s by an argentinian farmer who uncovered a massive lower leg bone that he first thought was a petrified tree trunk of some sort however after paleontologists realized what he had found they investigated the locality further and managed to uncover more from this individual with the holotype the specimen the species is based on including several vertebrae parts of the hip and a fragment of a rib by the time it was described in 1993 although a couple more bones have since been referred to the species specifically two thigh bones the known remains of this animal are clearly relatively incomplete this is something you'll see as somewhat of a trend with these giant dinosaurs and makes their study quite frustrating sometimes nevertheless despite the incompleteness of the full skeleton it was obvious that argentinosaurus was a seriously huge animal and numerous different total size estimations have been given for it over the years many different paleontologists have attempted to calculate argentinosauruses total length and weight using various methods and the result has been quite a range of estimates total body length has ranged from about 27 meters up to a ridiculously huge 39.7 metres with many values in between also having been suggested some of these estimates can be dismissed straight away the 39.7 meter length was obtained when researchers measured the total length of a reconstruction of the sauropod on display in a museum in argentina however this reconstruction is obviously mostly hypothetical in its dimensions only being based on the currently very limited remains that are known so that length is not likely to be very accurate at the other end of the scale the smaller length of 27 meters or less was based on the assumption that argentinosaurus was placed more towards the base of the titanosaur grouping and so had a relatively shorter tail like other related basal titanosaurs additionally since its vertebrae are not as wide as another titanosaur that we'll look at in more detail soon puertosaurus it was assumed that it must have been a little smaller than the 27 meters calculated for this animal however the evolutionary position of argentinosaurus has actually been switched around quite a bit as new studies have revised its relationships and our current understanding of these sauropods places it in a more derived position now so this older estimate also may not be so accurate anymore using related animals to estimate the size of the incomplete argentinosaurus has been a technique used many times including in a 2006 study which viewed this dinosaur and other relatives as essentially just a scaled-up saltasaurus a highly derived and more completely known titanosaur resulting in a length of 30 meters for argentinosaurus similarly a 2008 study used the relatively complete remains of a specimen of titanosaur called futalognosaurus to base revised estimates of argentinosaurus on coming to the conclusion that it was likely somewhere less than 33 meters in length not exactly a definitive size but the study does also give the very sensible advice that researchers should be careful when giving size estimates to incompletely known dinosaurs such as these various other estimates have of course been made but many of the recent values given appear to be somewhere in the range of between 30 and 35 meters but again it's very difficult to say for certain how accurate these are without having a complete skeleton but what about the mass of these giant sauropods how heavy was argentinosaurus this is another area of lively debate with different methods being utilized in different studies and some researchers criticizing the use of certain approaches we'll look at the techniques in more detail shortly but again they're severely impacted by the limited fossil material known for this species the ranges of body masses calculated in different studies vary wildly with 50 tons or so at the lower end and up to 96.4 tons of the other using both volumetric methods and scaling equations the disagreements between calculations and different paleontologists means that we cannot say for certain how heavy argentinosaurus was but several of the recent estimates have put it at around 60 to perhaps 75 tons though this is excluding the more extreme measurements so argentinosaurus was huge absolutely but was it the biggest dinosaur well it still has a few competitors one of these other contenders is the species puertosaurus ruili another titanosaur from argentina that was named and described in 2005. frustratingly this dinosaur is known from even more incomplete remains than those for argentinosaurus with just four disarticulated vertebrae being the basis for the taxon however these vertebrae are incredibly interesting and indicate that this was definitely a huge organism one of the vertebrae like the second dorsal is actually the single widest vertebra known from any sauropod as it possesses two massive wing-like processes on either side the anatomy of the vertebrae does allow for some inferences about total mass and length to be made but again the incredibly fragmentary nature of the skeleton has led to many urgent caution when trying to calculate these values still shortly after it was first named the lead author of the paper gave a length estimate of between 35 and 40 meters and a weight of 80 to 100 tons now clearly these values should be treated with a fair amount of skepticism especially given the fact that the maximum diameter measured for the face of the centrum this part of the vertebra is 60 centimeters in both puertosaurus and argentinosaurus now you may be wondering why this is an important measurement well it's been suggested that the area of the face of the centrum that is the area that articulates with the vertebrae next to it is directly related to the mass of the organism since this is the region of bone that's going to have to bear the compressive load of the animal so considering the very similar measurements in argentinosaurus and protosaurus it appears unlikely that they would have been especially different in their body masses indeed more recent studies since the description of the sauropod have yielded results more in the range of 30 to perhaps 33 meters in length and a body mass of maybe 50 to 60 tons but once again it's impossible to know for certain how accurate these estimates are without more complete material one thing is clear though from the bones we do have it does seem like protosaurus was in the same rough size range of giant titanosaurs such as argentinosaurus and could certainly be a worthy competitor we'll just have to wait for more complete fossils to be found from both another giant sauropods that could potentially take the title for the world's biggest dinosaur is strangely enough another titanosaur from argentina named patago titan mayoram this was a very recently named dinosaur being described in 2017 and when its discovery was first announced it was hailed by almost everyone as the new largest dinosaur ever known to have lived and for once it's actually known from a fairly complete skeleton with many more of the bones actually being represented compared to argentinosaurus and protosaurus in the paper describing patago titan a total body mass of 69 tons was obtained when using one method of scaling using an equation while a different method a volumetric one gave a range of between 45 and 77 tons the exact value depending on the amount of soft tissues reconstructed and although not stated in the actual paper some of the early media reports gave a total length of 37 meters for this titanosaur however there's been a good deal of criticism about these reports of patago titan being the largest ever first of all it's clearly still in the mass range of the estimates for his other titanosaur relatives but even more specifically than that when looking at dimensions for the bones that can be compared between this dinosaur and argentinosaurus it's slightly smaller in every instance comparisons done by sauropod expert matt weddle of the excellent sv pal blog showed that the maximum diameter of the articulating face of the largest argentinosaurus vertebrae were larger just than in patago titan at 60 centimeters versus 59 centimeters additionally the largest female known for argentinosaurus is estimated to have been 2.5 meters long while in patagonic titan the largest is 2.38 meters long now to be fair the length of the upper limb bones by themselves are not the best indications of total body size but interestingly the circumference of the argentinosaurus bones are much greater than patago titan 2 even in another argentinosaurus femur that was shorter in length so it's argued that the fatter fimora and larger weight-bearing regions of the vertebrae in argentinosaurus compared to particle titan are evidence that as far as we can tell from the data available at the moment patago titan was not the largest species but yet again it's of course important to keep in mind that the limited remains of argentinosaurus make it difficult to say that any comparisons are completely trustworthy indeed in 2020 another paper was published which reevaluated the mass estimates given for particle titan originally using a modified scaling equation that resulted in a range of 42 to 71 tons and a mean of 57 tons which is actually similar to the ranges obtained in the first paper but certainly doesn't put this animal significantly above the estimates for the other giant titanosaurs the paper naming patago titan though did also make a fascinating discovery concerning the evolution of such massive body size in these organisms finding a previously unrecognized grouping of titanosaurs that includes most of the largest members such as patago titan argentinosaurus puertosaurus and others it therefore seems that gigantism developed somewhere at the base of this grouping giving rise to this clade of apparently similarly sized giants but not only that gigantism also evolved independently in another group of titanosaurs too hinting at some interesting ecological implications for why this might have occurred in these dinosaurs such as changes in the climate and fauna as well as possibly the rising dominance of angiosperms the flowering plants another aspect of this debate that must also be mentioned is the story of amphicelius fragilismus now officially known as mariponysaurus fragilis in 1878 in colorado a school teacher named oramel lucas and his brother made a remarkable discovery of a huge dinosaur vertebra and soon shipped it to the infamous paleontologist edward drinker cope well known for being one of the men involved in the bone wars a rivalry with another paleontologist to name and describe as many prehistoric animal species as possible coming from a site in colorado charmingly called cope's nipple the giant vertebra was late jurassic in age and was classified as a kind of basal diplodocoid called amphicelius giving it a new species name amphiceleus fragilimus and this vertebra was absolutely huge according to cope's description measuring 1.5 meters tall the bone was not even completely preserved resulting in a total height estimation of an astonishing 2.7 meters by some authors though we'll come back to that in a bit tragically this mysterious giant bone has since been lost with no trace of the vertebra being able to be located during the cataloguing of cope's collection after it had been sold and transferred to the american museum of natural history in the early 1900s even worse the quarry from which the fossil originally came from has also been lost despite attempts in the 90s to relocate it using ground penetrating radar so the elusive bone remains lost to us with just club's description and illustrations remaining what most likely happened is that the very basic methods used at the time to try and preserve fossils were not enough to maintain the fragile vertebra during the transportation from kopp's collection to the museum leading it to literally just crumbling away however we'll probably never be able to know for sure what the fate of this infamous fossil was nevertheless a lot of interesting developments have still been made regarding the giant vertebra based on the dimensions reported by cope various paleontologists have since used these to estimate a total body length and mass with some absolutely ridiculously huge values being given by some for example a paper in 2006 proposed a total skeletal length of 58 meters and a body mass of a hundred and twenty two thousand four hundred kilograms based on comparisons with diplodocus seeing as amphiceleus fragilis was thought to be classified as a basal relative of this dinosaur the paper noted that this length was actually also in the range of lengths calculated over a decade earlier by another paleontologist who gave an estimate of between 40 to 60 meters clearly then if amphiceleus fragilismus really did exist and had body proportions similar to diplodocus this very well could have been the largest dinosaur to ever have lived however this animal is understandably a very controversial species other researchers have cast doubt on the validity of cope size estimates even questioning the reliability of his illustrations and measurements arguing that a typographical error namely using an abbreviation from meters instead of millimeters could be what resulted in the perceived giant size of the fossil but since then it has also been shown that kope's measurements are likely reliable and the different abbreviations used were in fact common for the time however in addition to this it was then discovered that amphiceleus fragilis was actually not a member of the amphiceleus genus after all in 2018 a paper was published which re-examines the descriptions and illustrations of this infamous bone and very convincingly showed why the dinosaur it belonged to was likely a type of sauropod called arabachisauret now robakisarids are actually also the plodicoids so it hasn't moved all that far among the branches of the sauropod evolutionary tree however it did mean that the name had to be changed as such this animal is now known as maraponisaurus fragilamus but this reclassification did also come with some significant implications for its total body size the dorsal vertebrae of robachiosaurus are actually proportionally much taller than the equivalent bones and diplodocus notes diplodocus not diplodocoids meaning the giant height of the maripoonisaurus vertebra would actually result in a much smaller total length if this animal really was a robaki sword instead at somewhere around 30 to 32 meters so not quite the absolute largest of all time but maripounisaurus is nevertheless still getting up there as a solid contender additionally the reclassification hasn't affected estimates of its height which placed the dinosaur at 7.95 metres tall at the hips so it would absolutely still have been an astonishing animal to see in life as maripounisaurus illustrates the evolutionary placement of a dinosaur can have a massive effect on the outcome of his size estimates but there are also other highly significant factors that influence this a great deal too including the actual scaling methods used in recent years two main methods have been commonly used when estimating the dimensions of large prehistoric animals such as sauropods allometric and volumetric methods allometric methods involve techniques such as using scaling equations which have been found by measuring a certain part of anatomy and comparing the relationship to the total body mass of the organism in living animals and then applying such an equation to the known limb bones of a dinosaur a scaling equation commonly used for sauropods in recent years was derived from the relationship between the circumference of the upper limb bones and total body mass in living quadrupedal mammals and reptiles as this relationship was discovered to be fairly conserved and therefore thought to be applicable to extinct quadrupeds too volumetric methods on the other hand involved the creation of a digital mathematical or even physical model of an animal working out what the volume of said model is before then multiplying it by a scale factor and then by an assumed density of the actual living animal both of these methods have problems especially considering their application to dinosaur taxa which are sometimes known from incredibly fragmentary remains so caution in accepting these dimensions as entirely reliable is often advised by the paleontologists who use them however it's generally accepted by researchers the volumetric methods are much more reliable for calculating body mass of extinct animals than allometric ones being much more precise and accurate in comparison as well as being relatively cheap and easy to do but still the calculated estimate will also rely on the amount of soft tissues and various densities assumed for the taxon in question which can be a matter of quite a bit of debate with non-avian dinosaurs such as sauropods a perfect example of the controversy of the scaling methods in these animals concerns the case of dreadnaughter's shrani another huge titanosaur discovered in argentina the significant thing about this sauropod is the fact that the fossils known from it are far more complete than any of the other giant argentinian titanosaurs with about 70 percent of the body skeleton recovered and when the description of dreadnaughtus was first published back in 2014 this meant that paleontologists studying it were fairly confident in the mass estimates they gave using the previously mentioned scaling equation based on the circumference of the humerus and femur bones which were both preserved in dreadnoughtus a mass of about 59.3 tons was calculated while not quite as large as the values for the later named patico titan all the ranges variously estimated for argentinosaurus and puertosaurus at the time of its description this was the largest mass estimate for a sauropod that could seemingly be confidently estimated based on the relative completeness of its remains and so it was hailed by the media and by the paleontologists who named it as potentially one of the most massive sauropods found so far however other paleontologists did not exactly agree with this conclusion almost immediately after the publication researchers such as the previously mentioned sauropod expert matt weddle investigated the mass estimates for dreadnaughtus using volumetric methods instead finding that when taking into account the body shape and the fact that sauropods had extensive air sac systems as well as airspaces within their bones which would have reduced their density a mass of 35 to 40 tons was far more plausible then in 2015 an actual paper was published by different paleontologists who re-evaluated the original dreadnought as mass again and used volumetric methods to illustrate that a much lower mass was more likely creating a series of volumetric models using a technique called convex hulling this study calculated a mass of the animal at a minimum convex hole volume then at 21 expanded volume and then maximal mass with a 50 percent greater trunk segment volume and all other segments being 100 greater these increases in volume were representations of greater mass and more extensive soft tissues in the live animal since as i mentioned earlier this is an important factor to keep in mind the study then also increased the volume of the model by the amount that would be required to achieve the original mass estimate of 59.3 tonnes and what they found was that this was a ridiculously unrealistic amount of extra soft tissue for this animal to have had in life instead a mass of between 22.1 and 38.2 tons was deemed much more consistent with the soft tissues that should be present and the relative densities of those tissues the paper also highlights some of the main concerns and problems with these mass estimation techniques calling for further collection of density and volume data in living animals so that more plausible limits and extinct ones can be determined as well as investigation into the discrepancies between volumetric modelling and scaling equation approaches that seem to keep occurring in estimates of extinct dinosaur masses neither methods are perfect and are of course made much more challenging by the limited remains of the animals they're often being applied to but with further study and our increasing knowledge of dinosaur anatomy it seems likely that volumetric estimates will continue to become increasingly refined over time still this is definitely another reason to remain cautious when estimating the mass of an extinct animal anyway this video has ended up being much longer than i originally intended as so often happens on this channel as such i've decided to split it up into two parts since we still have much more to cover to try and answer this question as well as other categories for the biggest dinosaur to consider such as length and height hopefully it won't be too long until the next part comes out i know i have a bad habit of taking a while to do the next parts for videos but life as a paleontology student is quite a busy one well i really hope you enjoyed this video and learned something new a big thank you to our patreon supporters too especially our dinosaur tier supporters amanda von nordeck archaeanthus bella anderson brent furman clara middleton dhruv srivastava george vojtek greg silvernail just f max corey peterson mike pace nicole bueno og khan persian boy robert thomas steve bradshaw and tiffany trammell if you would like to find out more about our world its history and the wonderful life that surrounds us all please feel free to subscribe to the channel if you think we deserve it and if you would like to see more from us

Channel: Ben G Thomas

Views: 439,629

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

Id: oi369_kEgP0

Length: 21min 20sec (1280 seconds)

Published: Sun Nov 21 2021