|
Spinosaurus News ~
|
11-28-2020, 05:39 PM
( This post was last modified: 11-29-2020, 04:37 PM by DrZapxX
Edit Reason: Typos
)
''Those vertebrae MAY belong to Spinosaurus but that is not 100% certain. I gave you the benefit of the doubt in assuming it did.
Also, have you considered that a density of 1 or more is still possible, even with airsacs, because most tissues as a whole are denser than water?'' The thing is, if you like it or not, they have been assigned to Spinosaurus, it's not a may, its confirmed for now, fsac kk 18118 is spinosaurus ignoring that sigilmassasaurus is spinosaurus too (fsca kk 720) Tissues vary with density, animals with the presence of air sacs (birds) have a density less than 1.0. ''Crocodilians naturally have a density of 1.05 kg/l following Asier Larramendi's works. What I actually did was give the head and neck of SpinoInWonderland's Spinosaurus a density of 0.9 and the rest a crocodilian density to show that even with airsacs an animal can be as dense or denser than water.'' See the thing is you never really specified this in the first place, you just magically applied a 0.9 density for SpinoInWonderLand's spinosaurus, which the actual image itself contradicts, also finding total density I would still think the total density is less than 1.0, (1.05+0.9 then /2) I believe Donald Henderson and Young nailed density correctly with a pneumatic neck,heads and body (based on other theropods) while having the limbs have a specific gravity of 1.05. ''I got it from Scott Hartman's blogpost, which has been clearly linked in my first reply to you. But if we're going to reference the date of publication, Asier Larramendi's work is more recent (2016), and suggests a density of 0.95 for the majority of theropods. This density has been used on significantly more pneumatic animals than Spinosaurus (eg: Aerosteon), and therefore I find it hard to believe a much less pneumatic theropod would have been as pneumatic or less than many theropods with a lot more airsacs.'' I've already discussed the sauropod argument of yours, Hartman doesn't specify how he got these densities, also the thing you quoted was in reference to SpinoInWonderlands image, I checked Sereno et al 2008, and I'm not aware of a density value of Aerosteon. ''That paper got their densities from dead birds that had lungs inflated to the very maximum (a far cry from live, relaxed sauropods with considerably less inflation in theirs), and it failed to take into account that the tissues were denser than water. Also, it should be noted that Wedel has overestimated the airspaces if we follow Larramendi, let me get a screenshot. *This image is copyright of its original author Larramendi seems to have covered everything on sauropod density that I can think of, and I don't see much reason at this point to doubt a density of roughly 0.9 for sauropods. And therefore, since sauropods are MUCH more pneumatic than Spinosaurus but still have a density of 0.9, I strongly believe Spinosaurus would be a good deal denser than what you suggest.'' I checked Wedel 2005, maybe you can too, I haven't seen any quote from their methods that they used dead birds, and why did you not take into my blog post from Wedel himself the author of the paper saying if anything he UNDERestimated sauropod density https://svpow.com/2009/03/16/brachiosaur...ncomplete/ This is a clear contradiction to what you are saying, theres no direct density value for tissues they vary, Wedel literally left out air spaces and halved the air volume from the lungs, I also showed you Henderson 2003 which have densities not even from Diplodocus that have much lower total densities than 0.9. ''There exists a difference between what you and I are using as a reference. Loons do not seem to fly as much as terns, gannets, pelicans, and grebes, and they also seem to spend more time in the water and dive deeper, so it is therefore presumable they are less pneumatic because of it. And I didn't say any airsacs at all would be detrimental, what I am saying is that an animal of 0.833 kg/l is far less realistic that 1+ kg/l given everything above. Finally, keep in mind that simply having airsacs does not prevent a density of 1 or more as shown above.'' Ummm, loons have known to fly 500 miles in a 24 hour period, they are just as aquatic as Grebes, and yes animals with air sacs have a density less than one, even with solid bones like loons. ''Or it could simply mean the size difference between those specimens is more than 32%. That would also be supported by the size of the corrected model from Henderson (2018) and some other skull reconstructions.'' Henderson got 15 metres from Ibrahim et al 2014, which in return favours 14.5 metres, which is dubious because of FSAC-KK 11888's length was not detailed on how it was 11 metres. ''t doesn't matter if it's peer reviewed or not, what does matter is if it's factually correct. And you have given no evidence suggesting it not to be other than fallaciously suggesting inaccuracy due to no peer reviewing. And show me where I'm taking anything as gospel here? I am aware nothing is truly gospel in palaeontology, so I'm simply endorsing what I find most probable.'' How do you define factually correct? In this debate you provided barely anything thats peer reviewed, I am not saying everything has to be, but the majority of your sources are poor resolution images or from people who aren't even experts, why don't you at least borrow the sources from those people which are in return peer reviewed? You see when something has been approved by two qualified experts, then it has much more reliability. Also could you mind not stating false statements, I have specifically stated much more reasons, the 32% skull difference between FSAC-KK 11888 and MSMN v4047's skull length, as well as Henderson and Therriens separate downgrade.You seem to reference SpinoInWonderLand way too much than you should, which is almost like taking his word for complete gospel we are all aware palaeontology is a ever changing field with newer discoveries Also it doesn't scientifically matter whats ''factual'' or not, this is science, science has to go through a process of being factual in the first place, anything that hasn't gone through the requirements is like it or not is invalid. ''Then would you mind explaining exactly why the larger estimates of theropod1 and SpinoInWonderland (especially that of SpinoInWonderland to which your argument of using a different species doesn't apply) are wrong? What you seem to be saying is that they are wrong because they are large, and you don't give any explanation for exactly why the skull reconstructions of either have been done wrongly.'' Because SpinoInWonderlands imagery placing is simply too simplistic (as if it was that simple!) aren't these skull reconstructions anyway? Theropod1's I have already explained because he/she like you claim used separate spinosaurid taxon, I am not saying that at all, if anyone you seem to be maximising the size of it, I am simply being more realistic, it is normal for prehistoric fauna to downgrade in size. ''In their sample size for the equation, they used Greg Paul's tyrannosaurid skeletals from Predatory Dinosaurs of the World, which happened to have rather short tails.'' You see I have checked Therrien et al and tried to quickly see if him and Henderson used Paul's 1988's skeletals, also I scaled Ibrahim et al 2020's spinosaurus and Pauls Tyrannosaurus, and its actually the opposite even with a curved tail it rivals the tail length,  *This image is copyright of its original author ''Can I see a source for this?'' It's literally from Henderson et al 2018 ''The digital Spinosaurus model used in the current study was based on the illustration provided in Fig. S3 of the Supplementary Materials of Ibrahim et al. (2014), and the geometry of the model was taken from this figure using the slicing method of Henderson (1999). The length of the model was also based on the new restoration of Spinosaurus by Ibrahim et al. (2014). These authors state that a life size replica of Spinosaurus, generated from their new skeletal data, was ‘over 15 m in length’ (last sentence, third paragraph). As measured from the tip of its snout to the tip of its tail, the length of the present digital model is 15.55 m. '' ''I don't recall referencing Mortimer's arguments here, therefore I do not see the point of that.'' You just been using his arguments from the beginning http://dml.cmnh.org/2007Mar/msg00292.html ''What on Earth are you talking about? I gave all my sources and methods right there in the post! If there is anything that you need clarification on, just ask. Edit: As it turns out, the skull length on the newest skeletal of the neotype from Ibrahim et al. 2020 is 122 cm, not 112 cm. Based on that and SpinoInWonderland's 186 cm estimate for MSNM v4047's skull length, MSNM v4047 would have been 16.63 meters long and 13.7 tonnes. theropod1's skull length estimate of 177 cm also yields a very large size - 15.86 meters and 11.8 tonnes. The mean of these 2 estimates is basically the same as the corrected model from Henderson (2018), so I'd consider these further support still for very large sizes.'' Not really, barely any sources at all just poor resolution images.I am not here to dissect you, I am here to post another side to the argument on my findings so a viewer could determine for his/her self The head NOT the skull, where does it say skull? Also this still gives a length of 160cm, I have gave my own mass estimates for 160cm (around close to 7 tonnes).  Quote:The thing is, if you like it or not, they have been assigned to Spinosaurus, it's not a may, its confirmed for now, fsac kk 18118 sigilmassasaurus unlike fsca kk 720 Nowhere did I say that those were not assigned to Spinosaurus. What I said was that the assignment is not 100% certain. Quote:Tissues vary with density, animals with the presence of air sacs (birds) have a density less than 1.0. Not necessarily, I have shown how it's possible for that not to be the case. And tissues do vary in density, but because muscle and blood (1.06 kg/l) as well as bone (2+ kg/l) and probably many more are denser than water, that would mean that a density of 1 or more is still possible even when there are airsacs. I don't know how many times I explained this already. Quote:See the thing is you never really specified this in the first place, you just magically applied a 0.9 density for SpinoInWonderLand's spinosaurus, which the actual image itself contradicts, also finding total density I would still think the total density is less than 1.0, (1.05+0.9 then /2) I believe Donald Henderson and Young nailed density correctly with a pneumatic neck,heads and body (based on other theropods) while having the limbs have a specific gravity of 1.05. I did specify that, maybe you just didn't read my post close enough. But give it a try yourself; the total volume of the head and neck is 1073.69 litres, while the rest of the animal is 9595.86 litres. If you multiply the head and neck by 0.9, and the rest by 1.05, I am not aware of any way to get an overall density of 0.9. Quote:I've already discussed the sauropod argument of yours I see. I'll discuss that with you further down the post. Quote:Hartman doesn't specify how he got these densities I'm not Hartman but he could have got them from Bates et al. 2009 (come to think of it, his densities are probably a bit conservative based on the work of both Bates and Larramendi). Quote:also the thing you quoted was in reference to SpinoInWonderlands image I'm a little bit lost on this. In my last post to you, the response paragraph that simultaneously dealt with Hartman's densities and what kind of density Aerosteon was likely to have had did not reference SpinoInWonderland's work. Quote:I checked Sereno et al 2008, and I'm not aware of a density value of Aeroteon. Sereno was not looking for a density for Aerosteon. Molina-Pérez and Larramendi were, however, and on every theropod in their book a graphic double integration was used with the 0.95 density. And I therefore will need evidence that a megaraptoran tyrannosauroid that's so pneumatic it was named for the air in its bones is going to have a higher density than an aquatic spinosaurid megalosauroid which could plausibly have been denser than 1 based on modern relatives. Quote:I checked Wedel 2005, maybe you can too, I haven't seen any quote from their methods that they used dead birds, and why did you not take into my blog post from Wedel himself the author of the paper saying if anything he UNDERestimated sauropod density https://svpow.com/2009/03/16/brachiosaur...ncomplete/ This is a clear contradiction to what you are saying, theres no direct density value for tissues they vary, Wedel literally left out air spaces and halved the air volume from the lungs, I also showed you Henderson 2003 which have densities not even from Diplodocus that have much lower total densities than 0.9. This abstract from Wedel's paper suggests otherwise; it seems as though dead and inflated birds were used as reference. Quote:Data presented by King (1966:table 3) indicate that the lungs and air sacs of birds may occupy 10%–20% of the volume of the body. Hazlehurst and Rayner (1992) found an average SG of 0.73 in a sample of 25 birds from 12 unspecified species. On this basis, they concluded that the lungs and air sacs occupy about a quarter of the volume of the body in birds. However, some of the air in their birds probably resided in extraskeletal diverticula or pneumatic bones, so the volume of the lungs and air sacs may have been somewhat lower. In the interests of erring conservatively, I put the volume of the lungs and air sacs at 10% of the body volume. Also, the things Wedel did not take into account were that the density of normal, relaxed sauropods is much higher as well as tissues being denser than water to begin with. Furthermore, Larramendi has outlined how the air spaces were overestimated in the original density of 0.8, and not even birds are that pneumatic when relaxed. Not to be blunt but you haven't been refuting Larramendi's proposition at all; you're just ragging about old stuff that his density estimation took into account. One last thing. I've spoken with Wedel in SVPOW's comments, and he thinks 0.9 is viable these days. So in conclusion, for Spinosaurus to have been significantly less dense than sauropods really does not seem viable from known data. Quote:Ummm, loons have known to fly 500 miles in a 24 hour period, they are just as aquatic as Grebes, and yes animals with air sacs have a density less than one, even with solid bones like loons. Are they really? Loons appear to spend more time in and around water and less time in the air going by what I could find. And nowhere did I say they couldn't fly, I said they did not seem to fly as much and were solid boned with a high density due to that. Quote:Henderson got 15 metres from Ibrahim et al 2014, which in return favours 14.5 metres, which is dubious because of FSAC-KK 11888's length was not detailed on how it was 11 metres. I'll go over Henderson further down, but I don't see why a discrepancy of more than 32% is dubious or incorrect. With the newest model and with the skulls restored using the same criteria, I am not able to replicate a mere 32%. Also, they simply restored the skeleton and got 11 meters or so. That's all that was done. Quote:How do you define factually correct? Exactly how it sounds, facts that are correct. Which can be just as viable non-peer-reviewed as they are peer-reviewed as long as they are correct. (An example of this would be saying that Spinosaurus was a reptile. That's just as correct coming from a non peer-reviewed source as it is from a peer reviewed one because it is factually correct that dinosaurs are reptiles and therefore peer review does not matter in that case). Quote:In this debate you provided barely anything thats peer reviewed That does not matter. What matters is how factually correct it is, and like I said before you don't seem to have any refutations save for the fallacy of no peer reviewing. Quote:I am not saying everything has to be, but the majority of your sources are poor resolution images or from people who aren't even experts, why don't you at least borrow the sources from those people which are in return peer reviewed? You see when something has been approved by two qualified experts, then it has much more reliablity. Why don't you actually take some time to point out why you think my images are wrong instead of constantly just ragging about no peer review as you are doing now? I don't need peer reviewed material for the above reasons, but what you need to do is actually point out why you think it is wrong. Quote:Also could you mind not stating false statements, I don't see what is so false about this. With both skulls restored using the same criteria, I just could not replicate a 32 percent size difference, and I don't know what Ibrahim did to get 32%. Simple as that. Quote:I have specifically stated much more reasons, the 32% skull difference between FSAC-KK 11888 and MSMN v4047's skull length, as well as Henderson and Therriens separate downgrade. Then the onus is on you to show how a difference of 32% can be obtained when both skulls are restored using the same criteria. I cannot replicate 32% as I can 52.5% and I don't know how Ibrahim got it, like I have said before. Quote:You seem to reference SpinoInWonderLand way too much than you should Nothing wrong with referencing him as much as I do, he is a good source so far as I can see. Quote:which is almost like taking his word for complete gospel Mind explaining how? It's simply what I find most probable, I think you know as well as I do that I am taking nothing for gospel here. Quote:we are all aware palaeontology is a ever changing field with newer discoveries That is the very reason I don't take anything as even close to gospel. I even stated this in my other post. Quote:Also it doesn't scientifically matter whats ''factual'' or not, this is science, science has to go through a process of being factual in the first place, anything that hasn't gone through the requirements is like it or not is invalid. Then please explain exactly what makes my non peer-reviewed arguments factually incorrect. Quote:Because SpinoInWonderlands imagery placing is simply too simplistic (as if it was that simple!) aren't these skull reconstructions anyway? I'm failing to see how being simplistic makes it wrong. The reason it was so simple is that all that needed to be done was superimpose the rostrum on a complete and undistorted Spinosaurus skull. That's it. And I find his skull reconstruction the most probable (but nowhere near gospel contrary to what you may think) given that it uses only Spinosaurus material. Just like I said before. Quote:Theropod1's I have already explained because he/she like you claim used seperate spinosaurid taxon That doesn't necessarily make for a wrong reconstruction. Can you please explain what turned out so wrong when the different taxa were used to fill in the gaps? Quote:I am not saying that at all, if anyone you seem to be maximising the size of it, I am simply endorsing what I find to be the most realistic based on known data. Quote:it is normal for prehistoric fauna to downgrade in size It is also common for them to upgrade in size. And based on known data, I find the latter most probable. Quote:You see I have checked Therrien et al and tried to quickly see if him and Henderson used Paul's 1988's skeletals, also I scaled Ibrahim et al 2020's spinosaurus and Pauls Tyrannosaurus, and its actually the opposite even with a curved tail it is longer That doesn't change the fact that the results from Therrien and Henderson (2007) end up too short compared to what 100% Spinosaurus material would yield, because for a given mass Tyrannosaurus is shorter than Spinosaurus. And that was my point, that that formula overestimates the weight but seems to underestimate the length. Quote:It's literally from Henderson et al 2018 That sounds like they are talking about the Ibrahim et al. 2014 model rather than the model that was used in the study. And given that nothing else was rounded off in the data table, I find it most likely that the 16 meter estimation refers to a non rounded measurement of the study's own model. Quote:You just been using his arguments from the beginning http://dml.cmnh.org/2007Mar/msg00292.html It's purely coincidental in that case, because I had not seen that entry of the DML until you linked it. But I will say that Mortimer does make good points there. Quote:Not really, barely any sources at all just poor resolution images. Everything had been explained in those posts. Including what changes had been made to the model, why those changes were made, and how they were made. I really do not see how that is no sources at all and just poor resolution images. Quote:I am not here to dissect you, I am here to post another side to the argument on my findings so a view could determine for his/her self And I am here to defend my viewpoints. Quote:The head NOT the skull, where does it say skull? Those can be used interchangeably when referring to things like dinosaur skeletals. Quote:Also this still gives a length of 160cm, As I said, I cannot replicate such a relatively low size difference between the 2 specimens. Quote:I have gave my own mass estimates for 160cm (around close to 7 tonnes). A 160 cm skull, even though it seems to be a serious underestimate for all the above reasons, would yield more than 8.7 tonnes. Now DrZap, I say this with all due respect, but I think it's time that you and I drop the debate with one another. We've had this debate multiple times already, it's been going on for quite a while, and we have been beating around the bush a lot. I also don't know if I'll change your viewpoints regardless of whether more people believe you or me. Whether you reply to this post or not, I don't think I will be continuing to debate. Anyone else who would like to know more can feel free to ask me about anything (including what DrZap says should they reply to this post), but I'd like to respectfully drop the debate with DrZap specifically for the reasons above. Edit: Seems DrZap has now replied to this post. I'm now up for questioning if anyone has any questions about their reply to me. 
11-30-2020, 08:10 PM
( This post was last modified: 11-30-2020, 08:20 PM by DrZapxX
Edit Reason: Typos
)
It turns out that Ibrahim et al 2014 overexaggerated on FSAC KK 1188 Spinosaurus's length, the 11 metres was a roundup of 10.37m (however this could been a revised length from Ibrahim et al 2020 but since it overexaggerated 14 to ''over 15 meres'' I am sceptical) which + 32% equals = 13.688 metres
''Nowhere did I say that those were not assigned to Spinosaurus. What I said was that the assignment is not 100% certain.'' Your kind of having doubt of it, we have no other option but to say they are Spinosaurus, I don't know how FSAC KK 18118 isn't spinosaurus when it's clearly been assigned to spinosaurus but sure. ''Not necessarily, I have shown how it's possible for that not to be the case. And tissues do vary in density, but because muscle and blood (1.06 kg/l) as well as bone (2+ kg/l) and probably many more are denser than water, that would mean that a density of 1 or more is still possible even when there are airsacs. I don't know how many times I explained this already.'' Idk where you shown that, blood and bone is a trait to many animals and they still have a total density around 1000km/3 including pneumatic birds. ''I did specify that, maybe you just didn't read my post close enough. But give it a try yourself; the total volume of the head and neck is 1073.69 litres, while the rest of the animal is 9595.86 litres. If you multiply the head and neck by 0.9, and the rest by 1.05, I am not aware of any way to get an overall density of 0.9.'' No, you really didn't, you just said SpinoInWonderlands image supports you with a density of 1+ despite a 0.9 neck, which the actual image does not have 900km/3 density in the head and neck also the thing is about that, that because the litres = kg and then volume is kg/1000 the density will always be a 1000, any total litres of volume will always have a 1000kg/m3 density ''I'm not Hartman but he could have got them from Bates et al. 2009 (come to think of it, his densities are probably a bit conservative based on the work of both Bates and Larramendi). '' Bit of an assumption to be honest.You just assumed this. '' I'm a little bit lost on this. In my last post to you, the response paragraph that simultaneously dealt with Hartman's densities and what kind of density Aerosteon was likely to have had did not reference SpinoInWonderland's work.'' Oh, you was only responding to the last sentence of the quote, I don't know why you quoted the density calculation on SpinoInWonderlands image on imgur, but ok. ''Sereno was not looking for a density for Aerosteon. Molina-Pérez and Larramendi were, however, and on every theropod in their book a graphic double integration was used with the 0.95 density. And I therefore will need evidence that a megaraptoran tyrannosauroid that's so pneumatic it was named for the air in its bones is going to have a higher density than an aquatic spinosaurid megalosauroid which could plausibly have been denser than 1 based on modern relatives. '' I am not saying Aerosteon was more pneumatic than Spinosaurus, I am going to assume they assumed a 0.95 density because it would have been higher than the 0.9 density of more pneumatic sauropods? ''This abstract from Wedel's paper suggests otherwise; it seems as though dead and inflated birds were used as reference. '' I've checked the abstract, (this wasn't in the PDF I read) I also read the introduction too, where does it say this? Can you quote? https://arxiv.org/ftp/arxiv/papers/1302/1302.3267.pdf 'Also, the things Wedel did not take into account were that the density of normal, relaxed sauropods is much higher as well as tissues being denser than water to begin with. Furthermore, Larramendi has outlined how the air spaces were overestimated in the original density of 0.8, and not even birds are that pneumatic when relaxed. Not to be blunt but you haven't been refuting Larramendi's proposition at all; you're just ragging about old stuff that his density estimation took into account. One last thing. I've spoken with Wedel in SVPOW's comments, and he thinks 0.9 is viable these days. So in conclusion, for Spinosaurus to have been significantly less dense than sauropods really does not seem viable from known data.'' You see Larramendi is being contradicted by the words of Welder himself who said he underestimated Diplodocus's air spaces, birds can have much lower densities than that some as low as 0.6, you see if we take Larramendi's supposed increase to 0.9, by changing the sauropods to a relaxed position, changing the soft tissue densities, and air space proportion this would have a 100kg/m3 increase, which is surprising has not a lot of effect, even when Welder missed out air spaces this would had to be <0.9 anyway, so if anyone Larramendi is overestimating specific gravity. Welder's comment also states 0.85 is just as reasonable too. ''Are they really? They appear to spend more time in and around water and less time in the air going by what I could find. And nowhere did I say they couldn't fly, I said they did not seem to fly as much and were solid boned with a high density due to that.'' I would say so according to Padilla 2015... ''Grebes are small- to medium-sized, heavy-bodied birds with long necks and feet set far back on the body. They have an almost exclusive aquatic lifestyle and are limited in mobility when on land.'' ''I'll go over Henderson further down, but I don't see why a discrepancy of more than 32% is dubious or incorrect. With the newest model and with the skulls restored using the same criteria, I am not able to replicate a mere 32%. Also, they simply restored the skeleton and got 11 meters or so. That's all that was done. '' Because Ibhraim et al 2014 states this? If anything it should be less, since they overexaggerated alot of the values in the first place and Therrien et al 2007 agrees it's consistent with that 32% increase They didn't really back it up with any evidence, they just said 11 metres that's it, btw this would still give a 8700kg value at 14.5 metres. ''Exactly how it sounds, facts that are correct. Which can be just as viable non-peer-reviewed as they are peer-reviewed as long as they are correct. (An example of this would be saying that Spinosaurus was a reptile. That's just as correct coming from a non peer-reviewed source as it is from a peer reviewed one because it is factually correct that dinosaurs are reptiles and therefore peer review does not matter in that case).'' Ok then, I'll rephrase, how do you know its factually correct? The thing is it's more than that, your not even referencing genuine Palaeontologists, just one guy, the difference this, there is many peer reviewed literature supporting that from other a century? ''Why don't you actually take some time to point out why you think my images are wrong instead of constantly just ragging about no peer review as you are doing now? I don't need peer reviewed material for the above reasons, but what you need to do is actually point out why you think it is wrong.'' Why don't you show actual sources backing the ''factually correct'' ideas up at least, and then I would give it more attention? ''And I am here to defend my viewpoints.'' I wasn't attacking yours in the first place? ''I don't see what is so false about this. With both skulls restored using the same criteria, I just could not replicate a 32 percent size difference, and I don't know what Ibrahim did to get 32%. Simple as that.'' They isometrically scaled both fsac kk 1188's premaxillae to msnmn v4047's premaxillae and got a percentage increase. ''That does not matter. What matters is how factually correct it is, and like I said before you don't seem to have any refutations save for the fallacy of no peer reviewing.'' Yes it does, you can't show 20 sources that are not scientifically reliable, and I did though. ''Those can be used interchangeably when referring to things like dinosaur skeletals.'' You don't know for certain, we are taking this for literal, head =/= skull, Ibrahim et al 2014 specifically states skull, Ibrahim et al 2020 states head,. ''Everything had been explained in those posts. Including what changes had been made to the model, why those changes were made, and how they were made. I really do not see how that is no sources at all and just poor resolution images.'' Because all of it was just coming from you? You aren't a source, you need to have sources backing your claims, its really that simple.Everything you linked were images. 'That doesn't change the fact that the results from Therrien and Henderson (2007) end up too short compared to what 100% Spinosaurus material would yield, because for a given mass Tyrannosaurus is shorter than Spinosaurus. And that was my point, that that formula overestimates the weight but seems to underestimate the length.'' I would say it was only off by less than a metre Fsac kk 11888's supposed length 10.37 metres Apply a 112cm skull gives 1.03161 * 10^(0.85673*Log(Skull Length)+0.93482) = 9.7836 metres this is off by half a metre (a 5.99% difference) and Paul's Tyrannosaurus has a longer tail proportionally than Ibrahim's 2020 spinosaurus restoration. ''I'm failing to see how being simplistic makes it wrong. The reason it was so simple is that all that needed to be done was superimpose the rostrum on a complete and undistorted Spinosaurus skull. That's it. And I find his skull reconstruction the most probable (but nowhere near gospel contrary to what you may think) given that it uses only Spinosaurus material. Just like I said before.'' Because why wouldn't Palaeontologists have done something so basic and simple in the first place, also I did the exact same thing and got less than 150cm, based on Ibrahim's 2020 skeletal. ''Then please explain exactly what makes my non peer-reviewed arguments factually incorrect.'' I have already. ''Mind explaining how? It's simply what I find most probable, I think you know as well as I do that I am taking nothing for gospel here.'' You take his findings and evidence for your own, it's self explanatory nearly 90% of the time you reference him. ''Nothing wrong with referencing him as much as I do, he is a good source so far as I can see.'' Really? I can reference other members of the Paleo community then? Who I agree with.Anyone can reference any enthusiast . ''That sounds like they are talking about the Ibrahim et al. 2014 model rather than the model that was used in the study. And given that nothing else was rounded off in the data table, I find it most likely that the 16 meter estimation refers to a non rounded measurement of the study's own model.'' ''The length of the model was also based on the new restoration of Spinosaurus by Ibrahim et al. (2014).'' It was based on Ibrahim et al 2014. ''Now DrZap, I say this with all due respect, but I think it's time that you and I drop the debate with one another. We've had this debate multiple times already, it's been going on for quite a while, and we have been beating around the bush a lot. I also don't know if I'll change your viewpoints regardless of whether more people believe you or me. Anyone else who would like to know more can feel free to ask me about anything, but I'd like to respectfully drop the debate with DrZap specifically for the reasons above.'' Fair enough I guess. I should have saw it before then I wouldn't have wrote all of this. 
It looks to me as though my suggestion of a crocodilian-like density for Spinosaurus, somewhat above that of water, may have been right on the money. Larramendi, Paul, & Hsu (2020) extensively examine the probable densities of a number of extinct animals, non-avian dinosaurs included, and have come to the same conclusion as myself: that Spinosaurus would most likely have had a density at least that of water if not somewhat denser, in contrast to the 0.833 density that DrZap and Henderson et al. 2018 have supported. Relevant parts in all quotes outlined.
Quote:A few extinct theropods appear to have been particularly dense, in particular the supposedly amphibious Spinosaurus (Ibrahim et al., 2014, 2020a; 2020b contra Henderson, 2018). Lines of evidence that appear to indicate an aquatic lifestyle for Spinosaurus, including recently discovered material attributed to S. aegyptiacus, reveals that these dinosaurs sported a transversely flattened tail with exceptionally developed caudal neural spines and chevrons apparently suitable for aquatic locomotion (Ibrahim et al., 2020b), long bones which are about 30%–40% denser than those of any other known theropod (Ibrahim et al., 2014), very poorly pneumatized or even apneumatic vertebrae (Rauhut, 2003; Ibrahim et al., 2020a, b), retracted nares (Ibrahim et al., 2014, 2020b), piscivorous adaptations of jaws and teeth (Dal Sasso et al., 2005), an elongated body, short hind limbs (Ibrahim et al., 2014, 2020a, 2020b) – although that needs to be verified by more complete remains– stable isotopes (Amiot et al., 2011) and apparently too short femur relative to its center of mass for a feasible bipedal locomotion on land (Ibrahim et al. 2020b), which is further supported by its remarkably small ilium and hindlimbs proportions relatively to its large BM (Larramendi and Paul, unpublished observations) suggesting a limited terrestrial performance. So, it is likely that the NSG of it, and perhaps other spinosaurs, was comparable to that of current crocodilians and other semi-aquatic animals at around 1.05. In the case of Spinosaurus it was probably able to regulate its FRC to achieve neutral buoyancy when diving. A recent study by Henderson (2018) that tested the hypothesis of a semi-aquatic Spinosaurus concluded that it was unsinkable. However, the study, which was based on a skeletal restoration that now appears obsolete, applied a too low SG to soft tissues and body parts, omitted that Spinosaurus vertebrae are largely apneumatic –which may suggest a restricted air-sacs system– and assumed an air-system similar to extant birds (although he tested an alternative model lacking air sacs, he committed the here mentioned errors) with the respiratory system normally fully inflated. Also excluded were possible gastroliths which despite their possibly limited mass (Cott, 1961, Henderson, 2003), could have increased the Spinosaurus NSG while lowering its center of gravity. As a result, Henderson (2018) obtained overly low SGs for all the analyzed animals in his study including a mean SG for Spinosaurus at only 0.833. For what it is worth (since this was brought up earlier), the paper also supports a density of over 0.9 for sauropods (that were much more pneumatic than Spinosaurus was) for the same reasons I outlined: Quote:The resulting NSG values in analyzed sauropods range from 0.917 to 0.984. These are significantly higher than estimated by Bates et al. (2016) which included most of the sauropod genera calculated here. They found very low SGs ranging from 0.776 to 0.929 –excluding their minimum convex hull models which further reduce the SGs–. Their low results are because the authors applied an overly low SG of just 1.0 to different apneumatic sections, and estimated extremely large respiratory systems for most of the sample which generally far exceed even what is expected in flying birds in a neutral state. Because the poorly pneumatized vertebrae of dicraeosaurids, the species in this clade were found to be the densest (Table 10), while the lowest NSG were found in the sauropods with the longest necks like mamenchisaurids, Giraffatitan, Barosaurus and Euhelopus with a NSG approaching to 0.93 in some cases. Colossal sized titanosaur carrying relatively large necks (Paul, 2019), were probably in this region (Table 10), or slightly below because their very wide torsos may have allowed them to possess relatively larger respiratory systems. If the lesser density of the neck of the neck relative to the rest of the body is not taken into account when calculating total BM, the later will be overestimated by up to ~3% among very large necked sauropods such as mamenchisaurs and brachiosaurs relative to short necked examples such as shunosaurs. The BM results herein are ~5-12% higher than for the same specimens volumetrically massed by Paul (2016, 2019) for the same specimens due to the lower NSGs used in those efforts. As well as 0.95 or more to be used with the majority of non-avian theropods (that were much more pneumatic than Spinosaurus as well) for the same reasons I outlined as well, since this point was brought up too: Quote:Turning to the nonavian tridactyl footed avepod theropods (sensu Paul, 2002: theropods that either possess a foot in which metatarsal I does not contact the tarsals, or descended from such theropods, and belong to the clade to the clade that includes Neotheropoda), estimating these dinosaurs’ densities is complicated because like their close avian relations, they probably had air sacs linked with their pneumatic postcranial skeletons (Paul, 1988b, 1997, 2002, 2016; O’Connor 2004; O’Connor and Claessens 2005; Henderson, 2018). But their body form was sufficiently different to complicate matters. Being flightless with few exceptions, lacking large sterna, and having large, airless tails, it is highly improbable that any nonavian theropod had as a large a neutral respiratory space as derived flying birds. Instead, it is terrestrial birds that run but do not fly that are superior density models for such dinosaurs. It follows that a NSG comparable to big ground birds would be expected for nearly all nonavian avepods, or a very little higher in the case of large theropods as their limb-bones, contrary of what is found in extant terrestrial birds, were not comparably pneumatized. As a result, the NSG for large avepod theropods, would be about 0.95, or a bit higher, somewhere between 0.95 and 0.99 in some cases, compared to 0.85 used for derived nonavian avepods in Paul (1988, 1997, 2016). @GuateGojira, you may be interested in this since we had this discussion earlier on the thread. Just as a comparison of the Henderson et al. 2018 model with the Ibrahim et al. 2020 model or with the mounted skeletons would suggest (as was outlined previously), the authors of the paper are in definite agreement with the suggestions of myself and SpinoInWonderland that Henderson's model was much too narrow. This is what is stated in the paper: Quote:Finally, the thoracic region of the 3D reconstruction of Henderson (2018) appears to be too transversely narrow, nonavian theropod anterior trunks tended to be somewhat wider and more rounded (Paul, 1997, 2016), especially so in view of the strongly arced rib illustrated by Stromer (1915 Plate 1, Fig. 15). That combined with the seemingly shallow pelvis would have resulted in a high and therefore more stable metacentric height. If the Ibrahim et al. (2020b) skeletal reconstruction is correct, then the sail backed dinosaur should have had better hydrodynamic stability than indicated by Henderson (2018). 
Very well done ! A pure instant of magic... A little spinosaurus animation.
I'll make it very brief for the reader to make conclusions about NSG of S.Ageypticus...
Crocodilians are not reliable indicators, even going from the paper itself it states crocodilians have NSG of 1.050 because of having no air sacs, and having hard dense dorsal osteoderms, with Spinosaurs because there's no evidence of crocodile like osteoderms as well positive evidence it having air sacs, therefore this would mean a density of at max 990kg/m3 would be most realistic, as animals with airsacs are less than 1000kg/m3. If we take the more pneumatic dinosaurs for face value, with a increased density this still reaches around 8 tonnes using upper length estimates.
I do think the following should be noted in regards to DrZapxX's reply:
-As the abstract states, terrestrial non-avian neotheropods, despite having significantly more air sacs than Spinosaurus, are estimated to be 0.95-0.99 kg/liter. This alone would disagree with the suggestion of a density of 0.99 for Spinosaurus at most, because your suggestion implies that animals like the hyperpneumatized tyrannosauroid Aerosteon, with airsacs so extensive they invaded its ilium, furcula, and gastralia, would have a similar density to an aquatic megalosauroid that either only had a small amount of airsacs in its neck, or simply none at all. Obviously the second is going to be denser. -As has been gone over well enough in the previous posts, simply having airsacs does not equate to a density less than that of water because the tissues themselves are a good deal denser. Like I went over above, highly pneumatized and terrestrial non-avian theropods are a good example of this (being not that far off from the density of water itself despite all those airsacs), and therefore I am more than certain that Spinosaurus would have been at least as dense as water if not more given its either very sparse or completely nonexistent airsacs. -While crocodilians do have osteoderms that have the potential to increase their density, it seems as though diving birds (with no osteoderms and a fat layer to stay warm that there is no reasonable basis to assume Spinosaurus had, so if anything the densities for the birds are underestimates given that fat layer) are also sometimes denser than water going by Ibrahim et al. 2020's mass estimate file. So simply not having osteoderms does not prevent the animal to be more dense than water. -A mere 8 tonnes is not at all realistic for a maximum size. Let's take Henderson's model for example; as was went over on Page 7 and as turned out to be precisely in agreement with what the new estimates on density suggest, it ends up over 12 tonnes (precisely 12.26) correcting the much too low density, the much too narrow torso, and no new tail. And this uses a density only equivalent to that of water; it could plausibly have been denser as was went over above. Considering all the mass estimates and whatnot I have outlined in this thread, I consider 10-13+ tonnes to be a much more plausible range for Spinosaurus than a mere 8 tonnes. 
Informative discussion. A few questions and discussion points from me...
Would it be possible for Spinosaurus to have pneumatized cervical vertebrae but then reduction/obliteration of such more caudally? The thought came to me from this quote from Ibrahim et al. (2020): "With much additional spinosaurid material now available for other taxa such as Baryonyx, Suchomimus and Ichthyovenator, we know that the extent of lamination and pneumaticity varies not only along the presacral column of single individuals as might be expected, but also between spinosaurid genera." From Lakin and Longrich (2019), an indeterminate spinosaurid's thoracic vertebra lacked pneumatization.: "FSAC-KK-18121 is a partial anterior thoracic vertebra. The neural arch is completely absent and the articular facet of the centrum is poorly defined. There is no central pneumatic foramen, nor is the parapophysis present on the centrum (Fig. 6G&6J), supporting the diagnosis of an anterior thoracic vertebra." I am unsure what trends are in other dinosaurs. However, a pneumatized skull and cervical column would allow easy access to air and above water vision which could fit with the aquatic behavior. Whatever the case, the obliterated medulla of the long bones need to be reconciled with the cervical pneumatization (assuming those are correctly assigned). A floating animal (<1 density) would either mean Spinosaurus stayed at the surface or the density is wrong if Spinosaurus was a sinking animal. Quote:Would it be possible for Spinosaurus to have pneumatized cervical vertebrae but then reduction/obliteration of such more caudally? The thought came to me from this quote from Ibrahim et al. (2020): I do agree that if those pneumatized cervicals really did belong to Spinosaurus, it is likely for the airsacs to have been limited to the neck or otherwise reduced elsewhere. Assuming that Spinosaurus had any airsacs at all, the only advantageous place to really have them would be that region; there's not really a whole lot that would benefit it from airsacs elsewhere. Quote:I am unsure what trends are in other dinosaurs. However, a pneumatized skull and cervical column would allow easy access to air and above water vision which could fit with the aquatic behavior. While you are correct that airsacs in the neck allow for greater ease in above-water activities, it is important to keep in mind that crocodilians are able to maintain a float and vision above water simply by inhaling, so Spinosaurus may not have necessarily needed airsacs to get a good breath, good view above water, etc. I'm not saying the assignments of pneumatic cervicals were definitely wrong, but that not having airsacs wouldn't necessarily be a disadvantage for the above activities. Quote:Whatever the case, the obliterated medulla of the long bones need to be reconciled with the cervical pneumatization (assuming those are correctly assigned). A floating animal (<1 density) would either mean Spinosaurus stayed at the surface or the density is wrong if Spinosaurus was a sinking animal. I think the most parsimonious scenario if we were to assume that the animal had both pneumatic cervicals and very dense long bones is that the overall density could be changed at will by inflating and deflating the airsacs as needed. In this scenario, with the airsacs inflated, the whole density would be slightly less than water for an easier time floating, but with the airsacs deflated when the animal was underwater (as it presumably would be most of the time), there wouldn't be anything preventing it from being at least as dense as water if not moreso. (12-16-2020, 12:36 AM)DinoFan83 Wrote:Quote:Would it be possible for Spinosaurus to have pneumatized cervical vertebrae but then reduction/obliteration of such more caudally? The thought came to me from this quote from Ibrahim et al. (2020): I think the limitation with the crocodile comparison is the discrepancy in the neck. The crocodile has a much shorter and less mobile neck than Spinosaurus looking at the anatomy. With its long and seemingly flexible neck, I wonder if the body of Spinosaurus was underwater while it kept its head up to breathe as needed. Whatever animal those cervical vertabrae are from, is it correct to infer they would be surrounded by some type of air sac based on this study? If Spinosaurus was rather thin in the chest (please correct me if not, but I recall thin vertebra on Spinosaurus, which I am inferring to mean a lack of chest girth) and the thoracic vertebrae lacked pneumatization, it does not seem it had (space for) much lung/air sacs without sacrificing diving capability. I've never really delved into avian/theropod anatomy so please make all the corrections needed. Quote:I think the limitation with the crocodile comparison is the discrepancy in the neck. The crocodile has a much shorter and less mobile neck than Spinosaurus looking at the anatomy. With its long and seemingly flexible neck, I wonder if the body of Spinosaurus was underwater while it kept its head up to breathe as needed. You make a fair enough point. I do think the using the neck alone as the point of flotation would be useful for breathing assuming there were airsacs. Quote:Whatever animal those cervical vertabrae are from, is it correct to infer they would be surrounded by some type of air sac based on this study? I believe so, yes. However, the airsacs in question on those cervicals wouldn't have been very numerous in the first place given the relative paucity of attachment spots for them compared to animals like Aerosteon (in the study you linked). Quote:If Spinosaurus was rather thin in the chest (please correct me if not, but I recall thin vertebra on Spinosaurus, which I am inferring to mean a lack of chest girth) and the thoracic vertebrae lacked pneumatization, it does not seem it had (space for) much lung/air sacs without sacrificing diving capability. I don't think it's necessarily just the width of the animal we should be looking at, but also the overall shape. While Spinosaurus wasn't exactly thin in its chest (as you may remember reading about in the discussion on the Henderson et al. model a few pages back), it does not seem to me as though it would have been able to have a lot of lung or airsac space without having to worry about its buoyancy given the shape of its thoracic region. The reason for this being that birds as well as non-avian theropods with a lot of pneumatization (for example, tyrannosauroids like Aerosteon) have a very different thorax shape. As we can see in, for example, GetAwayTrike's skeletals, the highly pneumatic Aerosteon has a short and deep torso for its size compared to Spinosaurus, and so do all modern birds. And that makes sense - a sausage-like Spinosaurus is going to greatly inconvenience itself when it tries to inflate/deflate airsacs throughout that stretched out torso because it would take quite a while to get air sufficiently in and out of the airsacs given that the air must literally go on the longest route possible to get in and out of all those airsacs. Not to mention if it can't empty them out sufficiently, it faces buoyancy problems. TL.DR: The thorax in Spinosaurus is not at all what we see in animals with many airsacs and having them in such a thorax shape would be generally detrimental given how the airsacs work, so I think you are correct that there does not seem to be sufficient space for airsacs without it having to worry about how well it could dive. Quote:I've never really delved into avian/theropod anatomy so please make all the corrections needed. No problem. Any inquiries you may have, I will answer to the best of my ability.
I think to avoid getting into another debate which you proposed we should drop, I'll finally make an response and I'll let you be, I've only made this response and comment because of the new paper that I didn't bare in mind previously.
Not necessarily, 0.99 is the upper range, Larramendi proposes a lower 0.95 too, we do not know exactly the density of general theropods, so therefore a density of 0.99 for Spinosaurus is perfectly fine, as mentioned to you several times Spinosaurus was almost certainly post cranial pneumatic also just because the direct evidence is limited in the neck does not mean the other part of body wasn't pneumatic, in fact, it the dorsal vertebra described by Rauhut 2003, MAY be pneumatic however not to the extent of other spinosaurids. Since generic reptiles have a density of 1.0 while having no pneumaticity, crocodilians have no pneumaticity too, therefore I can only imagine a density of 0.05 being from the osteoderms alone, the air sacs do exist despite me telling you, and just because the direct evidence indicates they are sparse doesn't mean they only belong in the cervical vertebrae only.For certain, a density of 1.05 is way too much. Alexander 2006, states organisms with airsacs are less than than 1000kg/m3, diving birds are solely have higher specific gravities because of the dense plumage , removing the plumage the bird is pneumatic, because it has airsacs (even by not being pneumatic) check Larrimendi et al 2020. ''For example surface swimming anhinga are waterlogged, with only the neck and head above water, so their NSGs are about 1.0. But the situation is more complicated. Surface floating boobies, gannets, pelicans, diving ducks, grebes, loons, auks and penguins float with considerable freeboard, so their SGs, at least in part because of their feather shells, are below 1.0, in some cases significantly so. This is confirmed by the need of these birds including penguins (Sato et al., 2002) to propel their dives underwater, and their lesser need for active propulsion while returning to the surface. This is true even if the feather shell is collapsed due to water pressure at depth. At this time, it can only be said that the NSGs of diving birds excluding any feather shells, are probably in the area of 0.95.'' Also just a reminder, from Ibrahim et al 2020, a density for a neotype, without the certain cervical pneumaticity (and potential dorsal) with the already dense bones have a 1000kg/m3, therefore with the airspaces in mind I would expect <1000kg/m3, this is very consistent with what I already stated against Larremendi et al 2020. Despite most tissues being denser than water, the low density of fat neutralises this making flesh have a specific gravity of 1.0, flesh in itself is the same as water. I never even said having osteoderms mean a density less than water, what I did say was Larrimendi et al overestimated density based on niche and not the biology of the animals, because of the assumption of Spinosaurus having osteroderms and no air sacs and pneumaticity is a far cry from what we do know. Yes it really is, basing a 13.6 metre long MSMN V4047 with a 3.8 m3 volume individual I have already discussed, the problems of page 7 (lack of sources/poor sources), overestimating length ect (the size comparison of Carcharodontosaurus to Spinosaurus is ridiculously overexaggerated in favour of Spinosaurus) in fact theres really no need correcting Hendersons model just follow square cube law for FSAC KK 18888.
Thank you very much for respecting my wish not to get involved in a lengthy debate, I appreciate that.
Anyone else can feel free to ask me about absolutely anything in DrZap's reply. |
| Users browsing this thread: |
| 3 Guest(s) |