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Carnivorous dinosaurs other than the famous t-rex and spinosaurus..
Carnivorous dinosaurs other than the famous t-rex and spinosaurus..
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Carnivorous dinosaurs other than the famous t-rex and spinosaurus..
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@DinoFan83 :
About #75: OK, but I use your numbers quoted before at #70... " -An 8 ton T rex has a 1.5 meter skull, while a 7 ton Giganotosaurus has a 1.6 meter skull -A 7 ton Tarbosaurus has a 135.7 cm skull, while a 7 ton Mapusaurus has a 1.5 meter skull " T-rex's advantage: a more powerful bite force, by far. Carnosaur's advantage: a 10 cm longer skull i.e. a fifteenth longer (10cm/150cm). Not certain that the carnosaur's advantage could counterbalance the t-rex' one... 
@Spalea
Advantage? What advantage? That was kind of my point exactly; in a fight between the 2, a bite from the other animal would be decisive enough for a win. Therefore, each animal has an equally deadly bite. And a skull that's 10 cm longer means that the carnosaur has that much more of a chance of landing the decisive bite. (09-26-2019, 08:13 PM)Spalea Wrote: @DinoFan83 Oh, sorry! Maybe you misunderstood me. The message I was trying to convey, simplified: -Even with a 12.5% mass disadvantage, Giganotosaurus still has a bigger skull -At parity, a larger skull would give it more of a chance of landing a decisive bite -That gives it the win  (09-26-2019, 08:41 PM)DinoFan83 Wrote:(09-26-2019, 08:13 PM)Spalea Wrote: @DinoFan83 Bigger in what sense.... Longer? Wider? Heavier? What about teeth as well? Bending Strength, Robustness, Length? There are many factors that goes into it. Tigers for instance have a shorter skull than Lions but usually are wider a parity with larger muscle attachments and thus their bite force is higher. A 3'' difference in length on a long skull isn't more of an advantage than a heavier, wider and more muscle packed skull. Neither animal is going to kill the other with one bite, thus the one that does more damage usually wins out. But there are examples against that too... For instance a GWS vs a Croc Crocs have a higher biter force while sharks have a more damaging bite but this shows clearly in their preferred method of attack. GWS's will bite then sit back and let the prey bleed out while a Croc will bite and hold, but I'm not sure eithers teeth fit into the sharks category, correct? (09-26-2019, 09:15 PM)Pckts Wrote:1: Yes, it is longer. Weight is likely similar while T rex has a slightly (key; slightly wider skull, and at the base, not really the jaw)(09-26-2019, 08:41 PM)DinoFan83 Wrote:(09-26-2019, 08:13 PM)Spalea Wrote: @DinoFan83 See this chart for a better idea: https://cdn.discordapp.com/attachments/583074799836856350/617003995638005770/comparison.jpg 2: Length is similar, robustness and strength are inferior but that is irrelevant as they do not need to be strong in that area for Giganotosaurus' strategy 3: My point was that the Giganotosaurus still possessed a larger skull with a 12.5% mass disadvantage, therefore its skull would be somewhat larger than that at parity 4: And they are equal in that regard - ignoring other factors such as size of the skull, a bite from a T rex/Tarbosaurus or Giganotosaurus would be equally deadly. 5: Yes, good example. That should fit well here. Seriously, I don't see what makes a tyrannosaurid's bite supposedly more deadly than that of a same sized carnosaur.  *This image is copyright of its original author Based off this representation I'd definitely say the T-Rex "Sue" has a significantly wider skull whether at the Base or the Snout. It also looks to have more area for muscle attachment. I'd compare it to a Nile or Saltie Croc to an Orinoco Croc. *not as exaggerated as the Orinico* The T-Rex also looks to have significantly more powerful neck and rib section as well, it to me just seems like it'd be the more powerful animal. Also the bottom 2 T-Rex's skulls look different than Sue's, almost like they'd be different sub species? Below is my Girlfriend with a T Rex Skull from the LA natural history museum, she's 5'8'' for scale  *This image is copyright of its original author
@Pckts
Yes, that is true. You need all of those things for a good crushing bite. But may I ask, how does that make it deadlier than the carnosaur's bite? Both animals have the power to turn the fight in their favor with a single bite. And about skull width, look at the weights! The carnosaurs are at notable size disadvantage (lower estimates), and even then the disparity with skulls is not that much. So at parity the carnosaurs would have comparable skull width and much bigger in all other dimensions. Moreover, I think both being larger in other dimensions and having wider gapes compensates for thinner skulls even with the mass disadvantages.  (09-26-2019, 08:41 PM)DinoFan83 Wrote: -Even with a 12.5% mass disadvantage, Giganotosaurus still has a bigger skullGiganotosaurus actually does not have longer (yes longer, not bigger. T-rex's skull is very volumous, even relative to its size) skull than T-rex does. The popular elogated skull that you see a lot on the Internet is an outdated reconstruction. For example, this one is an outdated reconstruction:  *This image is copyright of its original author This is something that Scott Hartman has pointed out quite a long time ago (like in 2013 or something): Scott Hartman Wrote:No, the elongated skulls are basically a myth. There's no such thing as a complete Carcharodontosaurus skull, and the one that NGS helped popularized is notoriously elongated beyond what the bones support (the nickname for that reconstruction is Pinnochio). But that was published while a team of sculptors was creating the Giganotosaurus mount, so they copied it assuming that it was a good guide. No carcharodontosaur ever had a skull like that, and Giganotosaurus was no exception. You can see in Hartman's reconstruction that the skull is not ridiculously elongated like what you see in the mounts  *This image is copyright of its original author Anyway, Franoys does provide the figures for his skull measurements:  *This image is copyright of its original author  *This image is copyright of its original author Going by the figures provided by Franoys, we can calculate the skull length relative to body mass: Skull length relative to mass = Skull length / Cubic-root(Body mass) (adjusted for square cube law) We will have: Giganotosaurus's skull length relative to mass = 8.06 T-rex's skull length relative to mass = 7.35 Which means that, assuming weight parity, the skull of Giganotosaurus is 9.6% longer (not bigger) than that of T-rex. Assuming Giga weighs as much as Sue, it will have a skull length ~ 167 cm. So at weight parity, the skull of Giganotosaurus is ~15 cm longer than that of Rex. However, i'm not sure what the point of assuming weight parity. There is no Carcharodontosaurid specimens that can be reasonably (emphasis added, so no, isometric scaling of fragmentary specimens will not be accepted) estimated to weigh as much as the big Rex specimens like Sue or Scotty. It's like saying that male Jaguar would beat male Lion assuming weight parity, which is pointless since male Lion is larger in real life. Yes, the specimens we have of Carcharodontosaurid are in no way representatives of their species so may be there are larger specimens out there, who knows. But in palaeontology, vague assumptions would lead you to no where. If you have no specimens, than no estimates, it's really that simple. In absolute term, Giganotosaurus's skull is not longer than that of T-rex. Also, i'm not sure how having slightly longer skull would dramatically improve the chance of an animal to land a decisive bite. Having longer skull would surely help increase the gape, even assuming similar gape angle. Some factors in favour of T-rex in landing a decisive bite such as binocular vision or agility that you might want to consider: Stevens (2006) regarding Tyrannosaurid's binocular vision: Quote:The binocular capabilities provided by a BFoV 55º wide and In contrast to Allosauroid who has a narrower field of binocular vision: Quote:The maximum binocular overlap for the allosauroid design Or Snively et al (2019) regarding Tyrannosaurid's agility: Quote:Tyrannosaurids consistently have agility index magnitudes twice those of allosauroids and some other theropods of equivalent mass, turning the body with both legs planted or pivoting over a stance leg. PhylANCOVA demonstrates definitively greater agilities in tyrannosaurids, and phylogeny explains nearly all covariance. Mass property results are consistent with those of other studies based on skeletal mounts, and between different figure-based methods (our main mathematical slicing procedures, lofted 3D computer models, and simplified graphical double integration). On the other hand, the Allosauroid's lighter and more lightly built head may help it to move its head faster (due to lower inertia) Anyway, i would place more weights on these factors when it comes to landing a "decisive bite" than having slightly longer skull... But anyway, it's up to you to decide which factors you think are relevant of course. (09-27-2019, 05:16 PM)Verdugo Wrote:1: And that may give Giganotosaurus a bit more of a chance because a larger skull will give more reach for a bite and allow a bigger area of a bite. (but not THAT much more, just a small edge)(09-26-2019, 08:41 PM)DinoFan83 Wrote: -Even with a 12.5% mass disadvantage, Giganotosaurus still has a bigger skull 2: True. However, confirmed sizes are close enough for a fair debate. And, as I said earlier in this thread, large theropods in general had decent weight ranges so I see absolutely no reason why that would not apply to big carnosaurs. Besides, my only point was why I felt carnosaurs were overall superior to tyrannosaurs at parity. And parity is pretty close from what we do know 3: A longer skull grants more reach, and therefore more of a chance to land that first bite, as well as a larger area bitten and damaged. And a wider gape only adds to the 2nd advantage. 4: Wouldn't these only hold relevance if the disparity was so significant as in, say elephant and mouse, or bat and ichthyosaur? I'm not discounting them but wouldn't they have to have more disparity to have a large impact? 5: My main point here was to make a case for carnosaurs against tyrannosaurs at parity; I have absolutely no idea where the myth of crushing bite>slicing bite stemmed from, and tyrannosaurids are often viewed as vastly superior parity fighters with no good evidence to back it up. (09-28-2019, 01:30 AM)DinoFan83 Wrote: 2: True. However, confirmed sizes are close enough for a fair debate. And, as I said earlier in this thread, large theropods in general had decent weight ranges so I see absolutely no reason why that would not apply to big carnosaurs.I already said above that i also think it's unlikely that the Carcharodontosaurid specimens we have are representative of their species. However, i have also pointed out that when dealing with extinct taxons, you need something more concrete than just some vague assumptions like 'how large this species could get'. One could also argue that some T-rex specimens could go pass 10 tonnes and it's just as legitimate as your argument that some Carcharodontosaurid specimens could go pass 8 tonnes. In fact, if not even more legitimate. For example, Hutchinson (2011) estimated the mass of Sue at 9.5 tonnes based on volumetric method (laser scanning the skeleton cast). And Sue is a complete skeleton. On the other hand, mass estimates of 8+ tonnes for Carcharodontosaurids are usually based on bad methodologies that do not have much scientific soundness to it such as isometric scaling of very fragmentary remains. In fact, we have an improve method of isometric scaling, it's called regression (because regressions allow you to incorporate more specimens and data). And even so, regressions are rather a hit or miss sometimes... The only sort-of legitimate 8+ tonnes estimates for Carcharodontosaurid comes from Hartman's Giganotosaurus MUCPv 95 based on assuming that it's 6.5% larger than the holotype. However, Hartman himself even stressed that 6.5% assumption is about as liberal as he will go Scott Hartman Wrote:7) I must reiterate, the lower jaw fragment of MUCPv-95 does not come from an animal that is 8% larger than the type. In fact it honestly could be from an identically-sized animal that just has a more robust dentary, so scaling it up 6.5% (in linear dimensions) should if anything be seen as the upper bounds.To summary, the 8+ tonnes estimates are quite concrete. On the other hand, the 8+ tonnes estimates for Carcharodontosaurids are meh, for lack of better words. Maybe one day we will discover larger specimens but let just wait for that 'one day' rather than making baseless assumptions... (09-28-2019, 01:30 AM)DinoFan83 Wrote: Besides, my only point was why I felt carnosaurs were overall superior to tyrannosaurs at parity. And parity is pretty close from what we do knowI figure parity debate would have been more interesting but that's not my point here. You can make a hypothetical assumption for a parity match-up between whatever animals as you like, i don't really care for that but you cannot state it as factual that Carcharodonosaurids weighs as much as those big T-rex specimens simply because, as i said above, i have yet to see anything concrete about 8+ tonnes estimates for Carcharodontosaurids. It's a possibility that they could weigh that much, yes, but where are the evidences? (09-28-2019, 01:30 AM)DinoFan83 Wrote: 1: And that may give Giganotosaurus a bit more of a chance because a larger skull will give more reach for a bite and allow a bigger area of a bite. (but not THAT much more, just a small edge)So you think that 15 cm more reach on 12+ m animals is a 'decisive' reach advantage but something like 'twice as much agility' (Snively 2019) or significantly better field of visions negligible? For example, if it takes a Giga 2 secs to make a 90 degree turn, it will only take a T-rex 1 secs to do that, that's essentially what it means to have 'twice as much agility'. Regarding visions, T-rex has better binocular vision than that of Hawks and in Stevens 2006's words, allows for 'judging the timing and direction of a terminal lunge' vs the narrower binocular vision of Allosauroid that would have 'detected preys on the basis of motions'. In fact, refer to Stevens 2006 Fig 8, Carcharodontosaurus actually requires to tilt its head downward about ~20 degree from the horizontal line just to achieve some narrow binocular visions. If it does not tilt its head downward to that point, it would have no overlapping visions at all and would literally have a blind spot right in front of its face. Now, obviously, not all Carcharodontosaurids are like Carcharodontosaurus but that it something to keep in mind here. Really can't see how having 15 cm more reach would be more decisive than these factors but i figure it probably depends on perspectives. (09-28-2019, 01:30 AM)DinoFan83 Wrote: I have absolutely no idea where the myth of crushing bite>slicing bite stemmed fromDidn't say anything about that. However, it's needed to point out that the whole crushing vs slicing bite things are not two mutually exclusive concepts and that animals can only pick one. For most macrophagous animals, it's actually somewhat in between. For instance, Tiger sharks' teeth allow it to crush and slice. Or Hyenas who are usually considered to be bone crushers can slice meat just as well (Hyenas have enlarged but blunt premolars for crushing bones and sharp carnassials/molars for slicing meat). T-rex's teeth have serrations that would allow it to slice meat to a certain extent (though obviously not as good as that of Carnosauria) Personally i would prefer something with robust teeth and skull that could facilitate 'jaw grappling' (holding, pulling, shaking, controlling). Personally, i can imagine that T-rex could survive if a Carcharodontosaurid bites down on its head, however, i can't imagine it the other way around. But again, different perspectives i suppose, i would not argue with you on this. 
Firstly, for those interested in the volumetric method this is a great read discussing many of the method's faults. Unfortunately, it is very subjective as the authors decide how fleshy or dense the animal is. This does not happen with isometric comparisons or regression.
While there are a plethora of estimations of therapods, it seems the raw data gets missed in the quest to find the magic formula. Based on the cEq equation of Campione (2014), Scotty has been given the highest weight. Nonetheless, as I stated in another thread, the limitation of the Scotty study is that it only takes into account femoral circumference, not length. The justification is that Campione (2012 and 2014) found femoral circumference to have the strongest correlation to mass. However, while the dataset of Campione is vast, this may bring in some inaccuracies. Animals very different in proportion are being compared and there is a wide confidence interval that indicates that another random dataset may show another measurement, such as bone length, as a stronger predictor. Thus, a combined measurement estimate should at least be considered. Another thing to note is that errors calculated by regression are simply the errors limited to the dataset itself. A better way to test for error is to test the regression in specimens not used to produce it but this has not yet been done. Here are the femoral measurements of the largest therapods:  *This image is copyright of its original author Scotty and the holotype Giganotosaurus can be compared by the follow method: Using measurement X, the amount specimen 1 is larger or smaller in terms of mass than specimen 2 = (Specimen 1/Specimen 2)^3 = Xm Using measurement Y, the amount specimen 1 is larger or smaller in terms of mass than specimen 2 = (Specimen 1/Specimen 2)^3 = Ym Overall amount specimen 1 is larger or smaller than specimen 2 in terms of mass = (Xm + Ym)/2 We will put Scotty as specimen 1 and the holotype Giganotosaurus as specimen 2 and substitute in the numbers to the above: Using femoral circumference, Scotty is Xm larger or smaller in terms of mass than specimen 2 = (590/520)^3 Scotty is 1.46x heavier than Giganotosaurus. Using femoral length, Scotty is Xm larger or smaller in terms of mass than specimen 2 = (1330/1365)^3 Scotty is 0.925x lighter than Giganotosaurus. Overall amount Scotty is larger or smaller than the holotype Giganotosaurus in terms of mass = (Xm + Ym)/2 = (1.46 + 0.925)/2 Scotty is 1.1925x heavier than the holotype Giganotosaurus overall. For the second larger Giganotosaurus cited to be 8% larger by the original work, we can extrapolate this specimen's femoral circumference to be (520 * 1.08) 562 mm and femoral length to be (1365 * 1.08) 1474 mm. We can go through the aforementioned math again as follows with the larger Giganotosaurus as specimen 2: Using femoral circumference, Scotty is Xm larger or smaller in terms of mass than specimen 2 = (590/562)^3 Scotty is 1.16x heavier than Giganotosaurus. Using femoral length, Scotty is Xm larger or smaller in terms of mass than specimen 2 = (1330/1474)^3 Scotty is 0.735x lighter than Giganotosaurus. Overall amount Scotty is larger or smaller than the holotype Giganotosaurus in terms of mass = (Xm + Ym)/2 = (1.16 + 0.735)/2 Scotty is 0.95x lighter than Giganotosaurus overall. Now I acknowledge Scott Hartman's estimate for the second Giganotosaurus being no more than 6.5% but his reasoning could be better explained before it's taken over the original work's determination. Persons et al. (2019) themselves do acknowledge that the holotype Giganotosaurus they used in their table is likely not the largest specimen for the species. 
I think that if we use modern animals, we can see that a crushing bite is better than just a slicing bite. T. rex have the most powerfull bite among dinosaurs, so he will need to bite the skull of its prey and that is all. Certainly, Giganotosaurus do not have that advantage. T. rex is more massive than Giganotosaurus, this discussion started by DinoFan83 is over even before it started.
By the way, I digged more and found no evidence that biggest Mapusaurus was even close to the weight of the biggest T. rex, so Franoys is right. Most reliable sources says that they weighed less, and just the biggest Giganotosaurus specimen (the little piece of mandible, and with a lot of speculation) barely reach the figures of T. rex. |
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