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Post by elosha11 on Aug 16, 2019 23:19:21 GMT 5
Bump. Any of you want to comment on this? I'm curious as to your thoughts. Nice thread. Although bite force is interesting, it seems Megalodon, Livyatan, and a more hypothetical 18 meter pliosaur would have enough brute bite force to inflict very damaging bites on their prey or (in a hypothetical sense) each other. To me, the full picture of biting formidability has to include (1) bite force, (2) bite volume and, relatedly, bite gape, and (3) type of teeth. Meg, Livy, and Plio all have very different mechanisms with regard to all these factors. If the pliosaur does not have sufficient gape, it's going to have a hard time biting critical areas of the very deep bodied shark and whale. It could attack flippers and tails but it might not be able get enough of a "mouthful" in the middle of body, if its long but thin mouth can't open wide enough. Livyatan may have had similar limitations in its gape. Whereas an animal like Megalodon has both a very wide and fairly deep set of jaws, and a very large gape. This gives it a lot more places to attack, and in the pliosaur, it's already going against an animal that is likely going to be thinner than it at equal lengths. As to type of teeth, it's slicing v. crushing as we've discussed in multiple threads. A shark like Meg would crush to some extent, along with primarily slicing, and Livy and a Pliosaur would certainly cut to some extent as well as crush. Either way can be extremely deadly, and at these colossal sizes, the animals will be doing both to some extent. Meg would shake their heads, allowing both bite force, muscle and serrations to do massive damage. Not sure about Livyatan, it might try to strip flesh with its bite more like an orca, or perhaps it just crushed down. Pliosaurs probably couldn't shake a lot after biting, as Verdugo has pointed out. That may be another comparative disadvantage. |
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Post by dinosauria101 on Aug 16, 2019 23:22:04 GMT 5
Bump. Any of you want to comment on this? I'm curious as to your thoughts. Nice thread. Although bite force is interesting, it seems Megalodon, Livyatan, and a more hypothetical 18 meter pliosaur would have enough brute bite force to inflict very damaging bites on their prey or (in a hypothetical sense) each other. To me, the full picture of biting formidability has to include (1) bite force, (2) bite volume and, relatedly, bite gape, and (3) type of teeth. Meg, Livy, and Plio all have very different mechanisms with regard to all these factors. If the pliosaur does not have sufficient gape, it's going to have a hard time biting critical areas of the very deep bodied shark and whale. It could attack flippers and tails but it might not be able get enough of a "mouthful" in the middle of body, if its long but thin mouth can't open wide enough. Livyatan may have had similar limitations in its gape. Whereas an animal like Megalodon has both a very wide and fairly deep set of jaws, and a very large gape. This gives it a lot more places to attack, and in the pliosaur, it's already going against an animal that is likely going to be thinner than it at equal lengths. As to type of teeth, it's slicing v. crushing as we've discussed in multiple threads. A shark like Meg would crush to some extent, along with primarily slicing, and Livy and a Pliosaur would certainly cut to some extent as well as crush. Either way can be extremely deadly, and at these colossal sizes, the animals will be doing both to some extent. Meg would shake their heads, allowing both bite force, muscle and serrations to do massive damage. Not sure about Livyatan, it might try to strip flesh with its bite more like an orca, or perhaps it just crushed down. Pliosaurs probably couldn't shake a lot after biting, as Verdugo has pointed out. That may be another comparative disadvantage. Maybe the sheer skull size of the pliosaur could make up for lack of skull shaking? I think they're all pretty even |
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Post by elosha11 on Aug 16, 2019 23:25:23 GMT 5
^ I don't really think even the biggest pliosaur skull/jaws are as big as Megalodon. In order of size/volume of bite, it seems likely to be Megalodon, Livyatan, hypothetical 18-20 meter pliosaurs. And their gape was less than Meg's as well. Very long but very thin jaws. Huge bite force for pliosaurs, but not necessarily a huge bite with less gape and such relatively thin jaws. Ok, I'm done for now, back to my work deadline...  |
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Post by dinosauria101 on Aug 16, 2019 23:30:13 GMT 5
Oh, that much? Meg's probably the superior.
And take as long as you need. No rush.
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Post by theropod on Aug 17, 2019 17:13:33 GMT 5
Verdugo: At least some pliosaur teeth are in fact serrated (Taylor & Cruickshank 1993 p. 412), I missed that earlier. elosha11: I think you are underestimating the overall size of pliosaur jaws. If, as proposed by McHenry, a 3m mandible corresponds to a 12.7m Pliosaurus, then a geometrically similar 18m pliosaur would have a 4.24m mandible. For reference, that would be a 54.6t pliosaur, also according to McHenry’s figures, equivalent to a 17.1m shark. An 18m megalodon, as you will recall, would be expected to mass around 63.8t. BRSMG Cc332, the smaller of the Westbury Pliosaurus sp. skulls has a (horizontal) gape of 75cm (Taylor & Cruickshank 1993 p. 408). The mandible is missing the symphysis, but by overall skull length the specimen is about 95% the size of the second westbury pliosaur, which has a complete 205cm mandible (Sassoon et al. 2012, supplement). So the gape width of a hypothetical 18m Pliosaur would be over twice that of BRSMG Cc332 (~1.6m). The holotype of Sachicasaurus has a mandible length of 273cm, and the width of the jaws from measuring Fig. 3 in Páramo-Fonseca et al. (2018) seems to be about 130cm. This would suggest 2m when scaled up. Calling this a "thin mouth" doesn’t seem very accurate, it is comparable to the width we would expect for the shark’s mouth: Scaling isometrically from the specimen you posted here (52.4 cm mouth width, 530 cm TL), a shark the same mass (17.1m long) would have a 169 cm wide mouth, a shark the same length (18m) would have a 178 cm wide mouth. I think you are getting a wrong impression of Pliosaur jaws being comparatively narrow or gracile from only looking at the skulls of ~10 or at best 20 ton pliosaurs and contrasting them with jaw reconstructions for very large adult megalodons based on the largest specimens available, which as restored would probably correspond to sharks in the 80-100 ton range, some of them even overblown for that. But for their size, pliosaur skulls are far from narrow. As for shaking, again, this might hold true for some pliosaurs (such as Kronosaurus, based on McHenry’s results), but with Pliosaurus’ snout having similar 2nd moments of area to a large nile crocodile when scaled to the same length, I don’t see how shaking is so out of the question in its case. You wouldn’t assume a gharial skull and a saltwater crocodile skull are structurally the same either just because they are both crocodilians, would you? Further testing would no doubt be needed on this, but the suggestion that pliosaurs were limited in their predatory capacities due to weak skull architecture seems fishy. I don’t know what exactly led Foffa et al. to make that suggestion, but perhaps it had to do with gullet size and the prey size it could have swallowed whole. As you know there are bite marks left by pliosaurs on Leedsichthys fins, a prey item likely larger (by mass) than the attacking pliosaur itself, so it appears they are certainly able to hold their own in terms of relative prey size, which would suggest their jaws were effective in this function. Páramo-Fonseca, M.E., Benavides-Cabra, C.D., Gutiérrez, I.E., Páramo-Fonseca, M.E., Benavides-Cabra, C.D. and Gutiérrez, I.E. 2018. A new large Pliosaurid from the Barremian (Lower Cretaceous) of Sáchica, Boyacá, Colombia. Earth Sciences Research Journal 22 (4): 223–238.
Taylor, M.A. and Cruickshank, A.R.I. 1993. Cranial anatomy and functional morphology of Pliosaurus brachyspondylus (Reptilia: Plesiosauria) from the Upper Jurassic of Westbury, Wiltshire. Philosophical Transactions of the Royal Society of London B: Biological Sciences 341 (1298): 399–418.
Sassoon, J., Noe, L.F. and Benton, M.J. 2012. Cranial anatomy, taxonomic implications and palaeopathology of an Upper Jurassic pliosaur (Reptilia: Sauropterygia) from Westbury, Wiltshire, UK. Palaeontology 55 (4): 743–773.
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Post by Grey on Aug 17, 2019 18:22:11 GMT 5
The sheer width of the skull of some pliosaurs is also what brought me to reconsider the question of the power generated by a hypothetical 15-18 m pliosaur.
Regardless of any media exaggeration, the preliminary description of the Svalbard pliosaurs clearly suggestted an all mighty reptile.
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Post by Infinity Blade on Aug 17, 2019 19:11:22 GMT 5
Would it be reasonable to assume other Pliosaurus spp. had serrated teeth or is there some phylogenetic variation as to whether or not they are present?
Also, didn't Liopleurodon have tricarinate teeth? Or am I mixing it up with something else? Were its teeth serrated too?
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Post by theropod on Aug 17, 2019 20:03:21 GMT 5
The trihedral shape seems to be characteristic of the genus Pliosaurus, Liopleurodon teeth are more rounded in cross-section.
Don’t know whether there is phylogenetic variation in terms of the serrations among Pliosaurus species, tooth crowns often aren’t preserved (e.g. in P. funkei they are all broken), especially the large caniniforms.
At any rate, large Pliosaurus teeth resemble maxillary T. rex teeth more so than most crocodile teeth. Considering Pliosaurus also had similar bite forces, presumably the way the bite functioned could have actually been somewhat comparable.
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Post by Verdugo on Aug 21, 2019 6:50:07 GMT 5
However the strength profile of P. kevani’s skull closely matches that of a Nile crocodile scaled to the same skull length (Foffa et al. 2014). And that was a serious-sized crocodile, 63 cm in skull length according to the supplementary material. The difference in the skull strength also don’t really seem to correlate well with prey-size in these animals, at least I don’t think caimans and alligators are known to take proportionately larger prey than nile crocodiles, and the differences between the former two and the nile crocodile and pliosaur are at times greater than those between the latter two and a gharial (Foffa et al. 2014, fig. 4, p. 7). Consistent with this, bite force estimates were also similar between the pliosaur and crocodiles at equal skull length. So with Pliosaurus having similar skull-strength to a large nile crocodile scaled to the same skull length, and a proportionately longer skull, I don’t really see its "weak" skull being much of an issue for its predatory capabilities (it’s of course quite rare for large aquatic predators to take anything proportionately larger than a large nile crocodile would, pliosaurs probably being no exception). Are there any chances that Foffa 2014 may have made some mistakes with the Nile croc? Otherwise there are a lot of things here that logically do not add up simply because of that 'Nile croc' in Fig 4 of Foffa 2014. First thing first though, the results in Fig 4 are not really for the overall skull strength but for just the rostrum (50% snout length). Anywar here are some fallacies that i notice:  1. When adjusted to similar length, the seriously-sized Nile croc rostrum only performs equivalently to that of Baryonyx regarding medio-lateral direction bending and torsion (Fig 4D and 4F). The Nile croc even performs slightly less so than Baryonyx regarding dorsal-ventral direction bending per fig 4E. This does not really make much sense to me. A Nile croc of that size is a serious boss Croc with clearly very robust skull and rostrum. For instance, here is a record Nile croc's skull measured 68 cm in DCL ( source)  Just look at how robust it is, and this record Nile croc here is actually not that much larger than the one from Foffa 2014. I can't really see how it will have length-adjusted weaker rostrum than that of Baryonyx. 2. The boss Nile croc also perform significantly less than a sub-adult Gator when adjusted for length (Fig 4D-F). The sub-adult Gator is a small animal and not fully-developed (since it is not fully grown) with a Skull length of only 18.4 cm. Judging by its skull length, the animal probably weighs less than 100 kg. Even in absolute term, the boss Nile croc only performs marginally better than that of the sub-adult Gator in medio-lateral direction bending and torsion per Fig 4A and 4C. Again, i can't really see how a seriously sized boss Nile croc would perform only marginally better than a sub-adult Gator weighing less than 100 kg. 3. The conclusion of Foffa 2014 is also contradictory. For instance, the concluded that Pliosaurus will not be able to perform shake and twist feeding, and be restricted to hunting preys only half their size. Assuming Fig 4 is correct and that Pliosaurus performs equivalently to an adjusted Nile croc, than their conclusion makes little sense. Twist and shake feeding are Nile crocs' preferred methods for preys dismemberment; and Nile crocs have been recorded taking preys similar to their size or even larger (at 0:39). Like i said, clear logical fallacies here. If anyone can contact the researchers in Foffa 2014 maybe we can ask them to clarify this. Otherwise, i suggest the Nile croc in Fig 4 should be ignored at the moment for the purpose of our discussion regarding Pliosaurus's skull function. |
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Post by theropod on Aug 21, 2019 15:40:17 GMT 5
Verdugo: Yes they are just rostrum length, but the rostrum seems to occupy a similar proportion of the skull length for pliosaurs and mesorostrine crocodylians, so I would expect them to have similar skull lengths as well. 1) I think there are some problems with this point. Firstly, that is a logarithmic scale. What looks like a small difference there would actually be a pretty big difference in terms of the absolute values. Secondly, this is the same Baryonyx specimen analyzed by Cuff & Rayfield 2013, and their results appear to be consistent with this, especially the high dorsoventral bending strength but lower lateral and torsional strengths. If the specimen appears too strong at length parity to you, then this might be because the rostrum is incomplete, and the preserved portion scaled too large (42% of rostrum length, which they based on the old reconstruction from Charig & Milner’s description). This does not affect the other figures though, only the relative bending strength of Baryonyx. 2) This is also not as unreasonable as you make it seem, a subadult gator already has a very broad snout, even if those of adults get even broader, so corrected for length, it’s not surprising it would be stronger. Again, in absolute terms the crocodile performs much better than the gator, it’s merely on a logarithmic scale. 3) Yes, of course I have wondered about these statements as well. However if you have followed discussions on the DML, even among the professional community there is considerable disagreement on what constitutes a relatively large prey item, or how common it is for predators to take prey their own size or larger (there was a recent discussion on that issue with regard to whether theropods could bring down prey their own size or larger, and I had a very similar discussion on there with Mike Habib a few years back). Presumably, we can explain Foffa et al.’s statements as cautious, and as them considering what they are referring to to already be relatively large prey, which by all accounts it is compared to typical prey sizes taken by other marine predators. But whatever they imply for ecology, Foffa et al. clearly repeat their statement that the rostral bending strength indicators are comparable to C. niloticus, so there’s not much to discuss about that, even though there are aspects of the interpretation that remain debatable. Cuff, A.R. and Rayfield, E.J. 2013. Feeding mechanics in spinosaurid theropods and extant crocodilians. PLoS One 8 (5): e65295.
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Post by Verdugo on Aug 21, 2019 17:41:11 GMT 5
Verdugo : Yes they are just rostrum length, but the rostrum seems to occupy a similar proportion of the skull length for pliosaurs and mesorostrine crocodylians, so I would expect them to have similar skull lengths as well. 1) I think there are some problems with this point. Firstly, that is a logarithmic scale. What looks like a small difference there would actually be a pretty big difference in terms of the absolute values. Secondly, this is the same Baryonyx specimen analyzed by Cuff & Rayfield 2013, and their results appear to be consistent with this, especially the high dorsoventral bending strength but lower lateral and torsional strengths. If the specimen appears too strong at length parity to you, then this might be because the rostrum is incomplete, and the preserved portion scaled too large (42% of rostrum length, which they based on the old reconstruction from Charig & Milner’s description). This does not affect the other figures though, only the relative bending strength of Baryonyx. 2) This is also not as unreasonable as you make it seem, a subadult gator already has a very broad snout, even if those of adults get even broader, so corrected for length, it’s not surprising it would be stronger. Again, in absolute terms the crocodile performs much better than the gator, it’s merely on a logarithmic scale. 3) Yes, of course I have wondered about these statements as well. However if you have followed discussions on the DML, even among the professional community there is considerable disagreement on what constitutes a relatively large prey item, or how common it is for predators to take prey their own size or larger (there was a recent discussion on that issue with regard to whether theropods could bring down prey their own size or larger, and I had a very similar discussion on there with Mike Habib a few years back). Presumably, we can explain Foffa et al.’s statements as cautious, and as them considering what they are referring to to already be relatively large prey, which by all accounts it is compared to typical prey sizes taken by other marine predators. But whatever they imply for ecology, Foffa et al. clearly repeat their statement that the rostral bending strength indicators are comparable to C. niloticus, so there’s not much to discuss about that, even though there are aspects of the interpretation that remain debatable. Cuff, A.R. and Rayfield, E.J. 2013. Feeding mechanics in spinosaurid theropods and extant crocodilians. PLoS One 8 (5): e65295. 1. I don't really mind the fact Baryonyx's rostrum has high dorsal ventral strength. However, how are you supposed to explain that Baryonyx also has similar medio lateral and torsion strength to that of Nile croc per Fig 4D and 4F? You even said it yourself that Baryonyx would have low medio lateral and torsion strength, why would it be similar to that of a predator who is well-known for their lateral shake and torsion feeding? Even Foffa 2014 stated that animals that have broader rostrum would perform better in medio lateral bending: "For example, broad rostra show greater bending resistance about the dorso-ventral axis (i.e. bending in a mediolateral direction, Iy) than about the medio-lateral axis (i.e. bending in a dorsoventral direction, Ix;Iy ≫ Ix). As a consequence, such shapes perform well in lateral shaking feeding."Why would a Nile croc, who clearly has relatively broader rostrum that those of P.kevani and Baryonyx, only perform equivalently in medio-lateral bending? Also, why does the fact that Baryonyx specimen is incomplete have anything to with its strength anyway? As you can see in Fig 4, they did adjust for the fact that the Baryonyx is incomplete. The purple line of Baryonyx stops at the ~40% mark while for other, their lines stop at 50% mark. 2. I can accept this explanation though it's not satisfactory 3. Okay so predator-prey size ratio is debatable. But how are you going to explain that they concluded that P.kevani will not be able to perform shake and twist feeding even though its rostrum strength is comparable to that of Nile croc (assuming that Fig 4 is correct), an animal who is well-known for their shake and twist feeding? Let me restructure this sentence for you: "Based on our test, we found out that the rostrum strength of P.kevani is relatively comparable to that of C.niloticus, an animal who is well-documented for their shake and twist (death-roll) feeding style, thus we concluded that P.kevani would NOT be able to perform shake and twist feeding". Be honest with yourself, does that really make any sense to you? The result from Fig 4 and the Conclusion are contradictory to each other and thus, they are mutually exclusive. There is no explanation to satisfy both Fig 4 and the Conslusion/Implication. There can only be one that is correct here. |
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Post by theropod on Aug 21, 2019 18:03:54 GMT 5
Verdugo: 1) The point is that the rostrum might have been scaled too large (Charig & Milner’s skull reconstruction is definitely outdated by now). That affects the relative strength when scaled to equivalent lengths, because the whole thing ends up being larger than it should be. Of course a larger specimen has a stronger skull. 3) Yes, and that is a somewhat weird conclusion given the data, but given this obvious contradiction, why would you choose to reject the raw data rather than their interpretation? Conclusions and Discussions are, by their very nature, debatable. Results much less so. If you find other results of Foffa et al. 2014 suggesting the strength comparison with the nile croc to be erraneous or calling its implications into question, please point them out. Of course the strength profile is only for the anterior parts of the skull, and there is other evidence in pliosaur skull morphology that suggests they didn’t engage in torsional feeding, unlike rhomaleosaurs (see Taylor & Cruickshank). As for shaking, I am at a loss for explaining why they reject it, but then, I am also at a loss for explaining why alligators have so much stronger skulls than crocodiles despite not doing anything obvious that would require them to be that much stronger.
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Post by sam1 on Aug 22, 2019 1:05:58 GMT 5
Don’t know. An 18m pliosaur would have a considerably longer skull overall, on the other hand that of Livyatan is extremely broad and massive for its length (at least comparable in terms of width). In terms of jaw mechanics and muscle configuration, they are quite different, obviously. And as far as jaw muscles or bite force of odontocetes is concerned, they are a total wildcard, nobody seems to have ever studied it. In fact, the only scientific estimate for a cetacean bite force that I am aware of is the one for Basilosaurus isis. So far all we can say about raptorial physeteroids is that their bites must have been very powerful, based on the strong teeth, robust jaws, bony exostoses on the jaw margins and the enlarged temporal fossae. How they compare to other large predators is hard to tell, though, as I mentioned before, I suspect that scaling up Basilosaurus would represent a lower-bound estimate, and this would at least suggest a bite force higher than the one likely reached by any reliable pliosaur specimen (be that large Kronosaurus specimens, Sachicasaurus or the Monster of Aramberri), especially if both were based on a comparable methodology. Can you shed some light on why exactly the pliosaur estimates are possible and physeter are not? Is it thanks to crocodile bite force measurements? What is the Basilosaurus' bite force estimate based on? Thanks |
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Post by theropod on Aug 22, 2019 2:13:49 GMT 5
Physeter??
Do you mean why there are figures for pliosaurs but not for Livyatan? That’s because people have conducted research on the bite force of these pliosaurs (from which one can hypothetically extrapolate bite forces for larger pliosaurs) and published that research, and because crocodiles appear to be fairly good analogues for pliosaur bite force, and there are sufficient in vivo data from crocodiles to derive an estimate that way.
On the other hand, I am not aware of any research, published or unpublished, on the bite force of any odontocete. The closest thing there is is the estimate for Basilosaurus, and it isn’t a very close analogue. We have previously made some attempts to extrapolate the bite force of Livyatan based on that estimate–with the associated caveats making the result very unreliable.
Then there is the additional problem of these estimates being derived from different methods.
The Basilosaurus estimate (Snively et al. 2015) is based on a combination of FEA and dry skull method. This can be compared to other estimates made using a similar method, e.g. Foffa et al.’s estimates for Pliosaurus, Wroe et al.’s estimates for Carcharodon or, to some extent, multi-body-dynamics based estimates for T. rex (though I think this method is much less prone to underestimate results, judging by how figures from McHenry 2009 and Foffa et al. 2014 and the MDA estimates from Bates & Falkingham 2012 compare to in vivo measurements from Erickson et al. 2012).
In vivo measurements such as those done on crocodiles are commonly 1.5-3 times higher than comparable dry skull estimates, so while those 24t I estimated earlier might represent a realistic peak bite force for a(n entirely fictional) 18m pliosaur, the 11-14t you’d get for Livyatan if you just scaled up Basilosaurus to skull length is almost certainly an underestimate, the question is just, by how much? However, this is potentially useful for comparing it to other estimates made using the same methodology, such as that for Pliosaurus kevani from Foffa et al. (a specimen with a 2m skull) at 1.7–4.9t (front–back), or the estimate for megalodon (a 48t specimen) at 5.6–10.9t.
At any rate, that 18m Pliosaur and the Livyatan would have fairly similar skull widths, so I would expect a similar ballpark of bite forces. Those in turn you can more properly compare to the ones based on other sharks’ in vivo bite forces, refer to grey’s post on the subject.
Bates, K.T. and Falkingham, P.L. 2012. Estimating maximum bite performance in Tyrannosaurus rex using multi-body dynamics. Biology Letters 8 (4): 660–664.
Erickson, G.M., Gignac, P.M., Steppan, S.J., Lappin, A.K., Vliet, K.A., Brueggen, J.D., Inouye, B.D., Kledzik, D. and Webb, G.J. 2012. Insights into the ecology and evolutionary success of crocodilians revealed through bite-force and tooth-pressure experimentation. PloS one 7 (3): e31781.
Foffa, D., Cuff, A.R., Sassoon, J., Rayfield, E.J., Mavrogordato, M.N. and Benton, M.J. 2014. Functional anatomy and feeding biomechanics of a giant Upper Jurassic pliosaur (Reptilia: Sauropterygia) from Weymouth Bay, Dorset, UK. Journal of Anatomy 225 (2): 209–219.
McHenry, C.R. 2009. ‘Devourer of Gods’: The Palaeoecology of the Cretaceous Pliosaur Kronosaurus Queenslandicus.University of Newcastle, 616pp.
Snively, E., Fahlke, J.M. and Welsh, R.C. 2015. Bone-breaking bite force of Basilosaurus isis (Mammalia, Cetacea) from the late Eocene of Egypt estimated by finite element analysis. PloS one 10 (2): e0118380.
Wroe, S., Huber, D.R., Lowry, M., McHenry, C., Moreno, K., Clausen, P., Ferrara, T.L., Cunningham, E., Dean, M.N. and Summers, A.P. 2008. Three-dimensional computer analysis of white shark jaw mechanics: how hard can a great white bite? Journal of Zoology 276 (4): 336–342.
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Post by sam1 on Aug 22, 2019 18:43:49 GMT 5
Physeter?? Do you mean why there are figures for pliosaurs but not for Livyatan? That’s because people have conducted research on the bite force of these pliosaurs (from which one can hypothetically extrapolate bite forces for larger pliosaurs) and published that research, and because crocodiles appear to be fairly good analogues for pliosaur bite force, and there are sufficient in vivo data from crocodiles to derive an estimate that way. On the other hand, I am not aware of any research, published or unpublished, on the bite force of any odontocete. The closest thing there is is the estimate for Basilosaurus, and it isn’t a very close analogue. We have previously made some attempts to extrapolate the bite force of Livyatan based on that estimate–with the associated caveats making the result very unreliable. Then there is the additional problem of these estimates being derived from different methods. The Basilosaurus estimate (Snively et al. 2015) is based on a combination of FEA and dry skull method. This can be compared to other estimates made using a similar method, e.g. Foffa et al.’s estimates for Pliosaurus, Wroe et al.’s estimates for Carcharodon or, to some extent, multi-body-dynamics based estimates for T. rex (though I think this method is much less prone to underestimate results, judging by how figures from McHenry 2009 and Foffa et al. 2014 and the MDA estimates from Bates & Falkingham 2012 compare to in vivo measurements from Erickson et al. 2012). In vivo measurements such as those done on crocodiles are commonly 1.5-3 times higher than comparable dry skull estimates, so while those 24t I estimated earlier might represent a realistic peak bite force for a(n entirely fictional) 18m pliosaur, the 11-14t you’d get for Livyatan if you just scaled up Basilosaurus to skull length is almost certainly an underestimate, the question is just, by how much? However, this is potentially useful for comparing it to other estimates made using the same methodology, such as that for Pliosaurus kevani from Foffa et al. (a specimen with a 2m skull) at 1.7–4.9t (front–back), or the estimate for megalodon (a 48t specimen) at 5.6–10.9t. At any rate, that 18m Pliosaur and the Livyatan would have fairly similar skull widths, so I would expect a similar ballpark of bite forces. Those in turn you can more properly compare to the ones based on other sharks’ in vivo bite forces, refer to grey’s post on the subject.
Bates, K.T. and Falkingham, P.L. 2012. Estimating maximum bite performance in Tyrannosaurus rex using multi-body dynamics. Biology Letters 8 (4): 660–664.
Erickson, G.M., Gignac, P.M., Steppan, S.J., Lappin, A.K., Vliet, K.A., Brueggen, J.D., Inouye, B.D., Kledzik, D. and Webb, G.J. 2012. Insights into the ecology and evolutionary success of crocodilians revealed through bite-force and tooth-pressure experimentation. PloS one 7 (3): e31781.
Foffa, D., Cuff, A.R., Sassoon, J., Rayfield, E.J., Mavrogordato, M.N. and Benton, M.J. 2014. Functional anatomy and feeding biomechanics of a giant Upper Jurassic pliosaur (Reptilia: Sauropterygia) from Weymouth Bay, Dorset, UK. Journal of Anatomy 225 (2): 209–219.
McHenry, C.R. 2009. ‘Devourer of Gods’: The Palaeoecology of the Cretaceous Pliosaur Kronosaurus Queenslandicus.University of Newcastle, 616pp.
Snively, E., Fahlke, J.M. and Welsh, R.C. 2015. Bone-breaking bite force of Basilosaurus isis (Mammalia, Cetacea) from the late Eocene of Egypt estimated by finite element analysis. PloS one 10 (2): e0118380.
Wroe, S., Huber, D.R., Lowry, M., McHenry, C., Moreno, K., Clausen, P., Ferrara, T.L., Cunningham, E., Dean, M.N. and Summers, A.P. 2008. Three-dimensional computer analysis of white shark jaw mechanics: how hard can a great white bite? Journal of Zoology 276 (4): 336–342.
Yeah I meant raptorial sperm whales, not Physeter. And I get what you're saying, that's why I asked in the first place..why are crocodiles good analogy for giant pliosaurs? What about T Rex for example? What is the method for calculating its bite force? Why can't scientist simply calculate the force of the jaw closing muscles of Livyatan? And again, what was the method for basilosaurus figure? |
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Nice thread. Although bite force is interesting, it seems Megalodon, Livyatan, and a more hypothetical 18 meter pliosaur would have enough brute bite force to inflict very damaging bites on their prey or (in a hypothetical sense) each other. To me, the full picture of biting formidability has to include (1) bite force, (2) bite volume and, relatedly, bite gape, and (3) type of teeth. Meg, Livy, and Plio all have very different mechanisms with regard to all these factors. 
