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Post by Grey on Aug 10, 2019 0:52:03 GMT 5
Theropod, weren't there some projections of pliosaurs bite force scaling from in vivo estimates ?
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Post by theropod on Aug 10, 2019 1:31:18 GMT 5
Me and coherentsheaf did some estimates based on Erickson et al.’s crocodile regressions back in the day I think.
These are the formulae in question:
all examined crocodylian taxa:
Y(bite force, N) = 29.632 x(body mass, kg) + 569.35; R² = 0.92
(captive) C. porosus:
y(bite force, N) = 115.39 x(body mass, kg) ^ 0.7629; R² = 0.98
A 31.6 t specimen (the estimated weight of a 15m Pliosaur based on McHenry’s thesis) would have estimated bite forces of 936.651 kN and 311.463 kN respectively. One problem you will have noticed immediately is how far these two regressions diverge when extrapolating so far outside the data range. The difference is relatively minor over the size range of extant crocodiles, but obviously they cannot both be accurate for something so much bigger (this already becomes quite noticeable in their estimate for Deinosuchus, whereas for a large saltwater crocodile their estimates are still fairly consistent).
I am generally sceptical of the relevance because of the differences in jaw morphology as well as head/body proportions, as well as the issues with comparing peak to sustained bite forces.
It also goes without saying that those figures cannot be compared to most bite force estimates based on computational methods, and with most bite forces we are focusing here being such estimates, that is a problem.
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.
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Post by Grey on Aug 10, 2019 2:37:35 GMT 5
Was the second published bite force estimate for meg somewhat comparable ? The one with anterior bite force twice higher than among in Wroe ?
If by being conservative we restrict meg at 50-60 tonnes of body mass, should we follow Wroe's method or the other obe to predict the bite ?
Would a 50-60 tonnes meg still have the highest bite force among all taxa ?
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Post by theropod on Aug 10, 2019 3:57:45 GMT 5
I am not sure I follow you fully; what other method than Wroe et al’s was there for estimating megalodon’s bite force? That is the only published attempt to calculate the bite force of either megalodon or Carcharodon.
According to Wroe et al.’s figures, a 60 t meg would have a posterior bite force of about 126 kN. As you know, Wroe et al. already provided an estimate for a near 50 t shark (47.7 t, 109 kN), but the corresponding bite force at exactly 50 t would be 112 kN.
As for whether that would be the highest bite force in the animal kingdom, more likely not. I would expect Livyatan’s bite force would have been higher than this. Scaling up Basilosaurus gives a figure very similar to that for Megalodon (111 kN), but this a bit of a lower bound estimate, basing on skull length and a figure at P4, not the posteriormost teeth.
Of course if what you mean are published figures, these estimates for megalodon are the highest to date, with the exception of Meers’ (2002) estimate for Tyrannosaurus (183 and 235 kN), though it is also true that the estimate for Deinosuchus by Erickson et al. is actually only less than 7kN lower than the one for the conservative max sized shark in Wroe et al.
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 Grey on Aug 10, 2019 4:35:38 GMT 5
You re not aware of that one ? "We used the relationship in Fig. 7 to predict the bite force of the extinct megatooth shark, Car- charodon megalodon. The maximum length of the mega- tooth shark has been estimated from tooth anatomy to be approximately 17 m (Portell et al. 2008) to 20.3 m (Got- tfried et al. 1996). Based on the relationship established in this study, a 17- and 20.3-m shark would possess an anterior bite force of 123,876 (95 % CI 80,595–183,849) and 179,219 (95 % CI 112,251–247,843) N, respectively. Wroe et al. (2008) used computer modeling and estimated a bite force of 93,127 N for a 103,197-kg (20.3 m, Got- tfried et al. 1996) megatooth shark. Our analysis suggests significantly higher bite force in this species. However, it is important to point out that the megatooth bite-force estimates presented here are based on the measurements of only 10 of the approximately 400 extant species of sharks. Clearly, the value reported here is only an estimate and additional adult bite-force data over a range of species are needed. The true bite force of this species will likely never be known, but as stated by Wroe et al. (2008) “C. megalodon is clearly one of the most powerful predators in vertebrate history.”" www.researchgate.net/profile/Glenn_Parsons/publication/291419180_Correlates_of_bite_force_in_the_Atlantic_sharpnose_shark_Rhizoprionodon_terraenovae/links/59e366e3458515393d5b8925/Correlates-of-bite-force-in-the-Atlantic-sharpnose-shark-Rhizoprionodon-terraenovae.pdf |
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Post by Verdugo on Aug 10, 2019 5:28:50 GMT 5
I think the implications of the "weak" skull are blown a bit out of proportion. We need to remember that a pliosaur also has a skull that is quite a bit larger relative to its body size than that of a modern crocodile. I wonder if Pliosaur really has 'larger' skull relative to its 'body size' than other animals though. Considering that Body Mass or Volume (if assume similar Density) is the most objective measurement of Body Size (we usually assume equal Mass when discussing Size Parity concept among vastly different groups of animals and not equal Length or equal Height), wouldn't Skull Volume also be a more objective measurement of Skull Size than linear dimensions like Length? McHenry paper rescaled Kronosaurus and Saltie to similar skull Volume and not similar skull Length when they made the comparison related to 'relative' skull strength of this animal. Anyway, you can see the details of the measurements in the screenshot in my post above. There are a couple of things that needed to be noticed: 1. The Kronosaurus's specimen has vastly greater Skull Length than that of the T-rex's specimen, yet only 2/3 the volume 2. When scaled to similar Skull Volume to that of the Saltie, Kronosaurus still has significantly longer skull 3. When scaled to similar Skull Volume, Kronosaurus achieved a fairly similar Body Mass to the Saltie, suggesting fairly similar Skull Volume/Body Volume ratio (or Head Size/Body Size if you will) Again, not sure if the whole 'big' headed notion of Pliosaur really holds up, maybe we should call them 'long' headed instead. Even when scaled to similar Skull Volume of Saltie (at similar Skull Volume, Kronosaurus's skull is still greater in linear dimension aka Length), the Saltie still outperformed Kronosaurus in many skull Strength measurements (also noted that the Saltie in McHenry is only 3.1m long, its skull does not exhibit the same degree of robustness that one would expect from a fully grown male Saltie). Another thing to keep in mind: Pliosaurus is anisodont, and has large caniniform teeth with carinae and smaller, conical teeth. the former are morphologically closer to T. rex teeth, whereas the latter resemble crocodile teeth. So I think we can assume their dentition functioned differently, and would require different mechanical properties from the skull. Aren't Crocodiles have Caniniform teeth as well? Anyway, do the Carinaes of Pliosaur have serrations? Monfroy (2017) pointed out that Croc's teeth also have Carninaes, though they lack serrations: "The main differences between Crocodylia and theropod teeth
were the carinae and the stoutness. Crocodylia and theropod
teeth showed two carinae on the AP axis, therefore forming sharp
edges. Theropod teeth have serrations along the full height of
the tooth crown, while Crocodylia do not exhibit any on the
carinae."One problem you will have noticed immediately is how far these two regressions diverge when extrapolating so far outside the data range. The difference is relatively minor over the size range of extant crocodiles, but obviously they cannot both be accurate for something so much bigger (this already becomes quite noticeable in their estimate for Deinosuchus, whereas for a large saltwater crocodile their estimates are still fairly consistent). I wonder if Log-Transforming could have helped controlling the Size factor and thus provide better model for extrapolation? Anyway, Aureliano et al (2015) used the same data from Erickson et al (2012), however, they log-transformed the data in order to estimate the bite force of Purussaurus. I wonder if we could use the same techniques here. As a natural trade off, maybe this is another indication of an incredibly powerful bite ? Arent there any chances that we actually underestimate their power ? Forrest once said there is three ou four times more space in pliosaurs jaws muscles than in crocodiles jaws muscles. As Theropod already said, it's a possibility that the Bite force estimates from models have been underestimated. However it's needed to be noted that the Bite force concepts itself may be different across studies. Foffa et al (2014) pointed out Bite forces from models are usually representatives of Sustained or Static bite force while Bite forces from in vivo are usually Impact or Peak bite force. Anyway, for apple-apple comparison, it's best that we compare Bite force estimates that were obtained from using similar methods. As you can see in the second screenshots in my previous post, Kronosaurus does appear to bite slightly harder than a Saltie when adjusted for Skull Volume. Kronosaurus (rescaled) Bite force (Front; Mid; Rear position respectively): 1500; 1700; 2700 N Saltie Bite force (Front; Mid; Rear): 1000; 1400; 2000 N Pliosaur are indeed quite impressive, Bite force wise. Of the three positions, the Mid position is the most important for prey capturing purposes since it's the the position of the Caniniform: "The middle of these (i.e. the M5 in C. porosus) is the largest tooth in the jaw, and is taken to be functionally equivalent to the M4 in Alligator and Caiman, M7 in Varanus komodoensis, M1 in Kronosaurus, and M4 in Tyrannosaurus (Table 7-6): these are comparable to the canines of carnivorous mammals, in that they are teeth with a ‘fang-like’ morphology that are predicted to be used in killing prey." |
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Post by theropod on Aug 14, 2019 0:03:22 GMT 5
I wonder if Pliosaur really has 'larger' skull relative to its 'body size' than other animals though. Considering that Body Mass or Volume (if assume similar Density) is the most objective measurement of Body Size (we usually assume equal Mass when discussing Size Parity concept among vastly different groups of animals and not equal Length or equal Height), wouldn't Skull Volume also be a more objective measurement of Skull Size than linear dimensions like Length? McHenry paper rescaled Kronosaurus and Saltie to similar skull Volume and not similar skull Length when they made the comparison related to 'relative' skull strength of this animal. Anyway, you can see the details of the measurements in the screenshot in my post above. You are right, I should have specified I meant long-skulled. Yes, that is true for Kronosaurus (even though the Kronosaurus in question wasn’t a very big specimen either). 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). Good point. I’ve never noticed any carinae on any brevi- or mesorostrine crocodile I’ve seen, so I just assumed they weren’t there. The serrations likely aren’t a big factor in T. rex teeth either though. Another good point. The second equation in Erickson et al. seemingly was log-transformed, which is probably why it gives so much more reasonable results than the first one. Actually it’s somewhat weird Erickson et al. used a linear model for their data in the first place, now that you mention it. Thanks for pointing this out!
Here are the formulae from Aureliano et al. 2015. log10(BF[N]) = 2.21779+0.66776*log10(BM[kg]) or BF[N] = 10^2.21779*BM[kg]^0.66776
For our 15m pliosaur (31590.23 kg), this gives us 166.8827 kN (but with a very wide 95% PI: 32.73795–850.690 kN), which indeed seems a lot more reasonable and also way less extreme compared to the computational bite force estimates of other sources (in vivo bite forces being 2-3 times higher, as we would tend to expect, is one thing, but that wouldn’t really be cutting it if in vivo-measurements were to suggest 90t…). For an 18m pliosaur using the same method, we’d get 240.4549 kN (44.36983–1303.105 kN).
Probably more interestingly, using McHenry’s mean estimate of 11.696 m and 14.976 t based on the vertebral width of the Aramberri specimen, which might be the biggest somewhat reliable pliosaur specimen at this date, we’d get an estimated bite force of 101.380 kN (PI 21.62081–475.3709 kN).
Aureliano, T., Ghilardi, A.M., Guilherme, E., Souza-Filho, J.P., Cavalcanti, M. and Riff, D. 2015. Morphometry, Bite-Force, and Paleobiology of the Late Miocene Caiman Purussaurus brasiliensis. PLOS ONE 10 (2): e0117944. 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.
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Post by Grey on Aug 14, 2019 2:48:22 GMT 5
So, if we ever find a ~18 m pliosaur, there are good chances that it would present the most powerful bite force ever in history then ?
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Post by elosha11 on Aug 14, 2019 3:14:06 GMT 5
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 Grey on Aug 14, 2019 3:32:08 GMT 5
Very debatable but it is interesting to notice how potentially powerful a 18 m pliosaur would be, nonetheless a match for the Neogene titans. While searching about pliosaurs size, I came to see the blog of this guy : psdinosaurs.blogspot.com/2019/05/size-calculations-for-pliosaurs.html?m=1Despite using recent studies as basis, he gets sizes up to 18 m for the larger pliosaurs. I m a bit confused by how he got those results. |
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Post by theropod on Aug 14, 2019 4:13:12 GMT 5
Very debatable but it is interesting to notice how potentially powerful a 18 m pliosaur would be, nonetheless a match for the Neogene titans. While searching about pliosaurs size, I came to see the blog of this guy : psdinosaurs.blogspot.com/2019/05/size-calculations-for-pliosaurs.html?m=1Despite using recent studies as basis, he gets sizes up to 18 m for the larger pliosaurs. I m a bit confused by how he got those results. Some of the math is faulty (somehow 14cm is 1.5% smaller than 15.5cm, and 17.1 cm is 1.6% larger than 15.5cm according to his calculations  ) and he uses a very simplistic methodology (using a single Liopleurodon specimen to scale up everything with a skull–not to mention that it is a specimen that doesn’t actually have any postcrania that he is using as a basis there, and a single Kronosaurus for everything with vertebrae). He also seems to be lumping a lot of different skull measurements into one by comparing all of them to the same figure, or at least he’s not clear as to how he accounts for the difference between the different measurements (which can be highly significant in some taxa, the famous 154cm long Liopleurodon skull described by Andrews is only 126.5cm long in condylobasal length). Some of the other stuff he writes is quite confusing though (his skull measurements for Kronosaurus for example), as well as why he ignores significantly more complete specimens’ measurements (like the Harvard Kronosaurus’ total length, which we can be fairly confident is not above 13m, and probably below it) in favour of estimating their size based on skull or vertebral length. Of course, many pliosaur size estimates use overly simplistic methods. Even McHenry, who for all intends and purposes was very rigorous as far as pliosaur size estimates go, based a lot of his estimates on a commercially available pliosaur model, including the proportions he assumed for things like P. macromerus. I do think this could benefit from being revisited at some point, but this only works if unambiguous (and not 3 different figures each for skull length and total length as in the Tübingen Liopleurodon) and detailed (more than just a measurement for a single vertebra in an entire skeleton) information on reasonably complete specimens becomes available. The Aramberri pliosaur, from what I hear, is currently being housed in several parts at two different institutions who don’t seem to cooperate very well, for example… |
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Post by Infinity Blade on Aug 14, 2019 6:29:21 GMT 5
Called it. I suspected a while ago that the Nile crocodile in their study was probably an adult. I just couldn't see any reason to think Foffa et al. would use an immature individual for comparison. I had no idea the size of the specimen was in the supplementary material all along, though.
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Post by Grey on Aug 14, 2019 6:54:20 GMT 5
Very debatable but it is interesting to notice how potentially powerful a 18 m pliosaur would be, nonetheless a match for the Neogene titans. While searching about pliosaurs size, I came to see the blog of this guy : psdinosaurs.blogspot.com/2019/05/size-calculations-for-pliosaurs.html?m=1Despite using recent studies as basis, he gets sizes up to 18 m for the larger pliosaurs. I m a bit confused by how he got those results. Some of the math is faulty (somehow 14cm is 1.5% smaller than 15.5cm, and 17.1 cm is 1.6% larger than 15.5cm according to his calculations ) and he uses a very simplistic methodology (using a single Liopleurodon specimen to scale up everything with a skull–not to mention that it is a specimen that doesn’t actually have any postcrania that he is using as a basis there, and a single Kronosaurus for everything with vertebrae). He also seems to be lumping a lot of different skull measurements into one by comparing all of them to the same figure, or at least he’s not clear as to how he accounts for the difference between the different measurements (which can be highly significant in some taxa, the famous 154cm long Liopleurodon skull described by Andrews is only 126.5cm long in condylobasal length). Some of the other stuff he writes is quite confusing though (his skull measurements for Kronosaurus for example), as well as why he ignores significantly more complete specimens’ measurements (like the Harvard Kronosaurus’ total length, which we can be fairly confident is not above 13m, and probably below it) in favour of estimating their size based on skull or vertebral length. Of course, many pliosaur size estimates use overly simplistic methods. Even McHenry, who for all intends and purposes was very rigorous as far as pliosaur size estimates go, based a lot of his estimates on a commercially available pliosaur model, including the proportions he assumed for things like P. macromerus. I do think this could benefit from being revisited at some point, but this only works if unambiguous (and not 3 different figures each for skull length and total length as in the Tübingen Liopleurodon) and detailed (more than just a measurement for a single vertebra in an entire skeleton) information on reasonably complete specimens becomes available. The Aramberri pliosaur, from what I hear, is currently being housed in several parts at two different institutions who don’t seem to cooperate very well, for example… Yes I had hears the German and Mexican teams didnt work well together... Do you suspect that McHenry estimates could be actually understated ? www.kronosrising.com/apex-predator-spotlight-pliosaurus-macromerus/I know, it's Max Hawthorne stuff, but this is a bit intriguing. He claims this pliosaur bone comes from a 15 m Pliosaurus per a scaling by paleoartist Andrew Cocks who built a very large (2.6 m while "fleshed") pliosaur head. But I m in contact with the guy and I m not sure at all Andrew Cocks actually did that at all. I will ask him. My understanding is that 15-18 m hypothetical pliosaurs could very well be contenders as for the title of the most potent biting carnivores in history. Is there really absolutely nothing to indicate anything grew larger than the ~12 m, 15 tonnes Aramberri pliosaur (still massive for a macropredator by any standard). Are we to expect marine apex carnivores massing 20 tonnes and more only from the Neogene or are there still some hints at the possibility of pliosaurs in the megalodon/Livyatan category ? What is certain, the potential power of destruction in the bite of a hypothetical 18 m pliosaur is mind-blowing. theropod, if a 18 m pliosaur could have 24 tonnes of pressure, could we expect Livyatan to have something in the same area ? Or are pliosaurs really more muscled ? |
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Post by theropod on Aug 16, 2019 18:24:48 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.
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Post by Grey on Aug 16, 2019 22:56:49 GMT 5
A bite force study for the killer sperm whales seems necessary.
I m would extremely curious to see such an analysis, pretty sure the results will be colossal.
But would they rival pr exceed the one in a large sized meg ..
As for the pliosaurs, they are almost uniquely fitted for biting, it of interest if there is still trace of one specimen that would be large enough to be consider a contender for the greatest carnivore, a real-life Predator X...
But so far, no reliable evidence of anything larger than 15-20 tons (yes it is massive nonetheless).
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) and he uses a very simplistic methodology (using a single Liopleurodon specimen to scale up everything with a skull–not to mention that it is a specimen that doesn’t actually have any postcrania that he is using as a basis there, and a single Kronosaurus for everything with vertebrae). He also seems to be lumping a lot of different skull measurements into one by comparing all of them to the same figure, or at least he’s not clear as to how he accounts for the difference between the different measurements (which can be highly significant in some taxa, the famous 154cm long Liopleurodon skull described by Andrews is only 126.5cm long in condylobasal length).
