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Post by Infinity Blade on Feb 16, 2015 1:20:35 GMT 5
This is for the posterior teeth as theropod said, correct?
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Post by coherentsheaf on Feb 16, 2015 1:39:53 GMT 5
Yes
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Post by Grey on Feb 16, 2015 2:43:12 GMT 5
Forrest comparing between pliosaur bite force and Livyatan's.
The geometry of the jaw musculature of whales is somewhat different.
The coronoid eminence around which the jaw muscles attach is more
posterior in the jaw, significantly reducing the force exerted at
tooth positions. Also, and unlike pliosaurs, the architecture of the
skull has to allow for a large brain, reducing the space available for
jaw muscles.
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Post by Infinity Blade on Feb 16, 2015 5:37:11 GMT 5
I had always thought the large brain of cetaceans would have reduced room for jaw musculature.
Gonna go out on a limb here. The discrepancy in force between what I think are the anterior and posterior tooth bite force figures in the Bates & Falkingham study is 22kN (57,000-35,000). If ~90-98.066kN (~9.2-10t) is a probable posterior bite force for Tyrannosaurus, I guess I would suppose an anterior tooth bite force of ~68-76.066kN (~7-7.7t) would be reasonable.
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Post by Grey on Mar 8, 2015 9:57:09 GMT 5
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Post by Grey on May 3, 2015 23:01:47 GMT 5
Foffa is currently working on the biting performances in marine reptiles, including Liopleurodon. More in few months..
He said me this about pliosaurs bite force :
It's true that the supratemporal fenestra in pliosaurids is comparatively much larger than in crocodiles. But that's not the only factor. As you said the muscle volumes are hard to understand because some muscles groups exceeds the bone boundary (muscle pterygoideus in crocodiles - and we simply don't know this about pliosaurs). Other factors are the muscle lines of action which influence the efficiency of the biting.
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Post by Grey on Jun 26, 2015 2:49:44 GMT 5
My understanding is that Tyrannosaurus bite force according to Bates and Falkingham was up to 5.7 tonnes of pressure in Stan specimen and the whole problematics suggest the whole maximum bite force was in the 5-10 tonnes range.
But really how Pliosaurus kevani compares to it ? Using the same problematics and assuming the same approach for Tyrannosaurus bite force, is there a whole likely range possible for P. kevani ?
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Post by theropod on Jun 26, 2015 12:27:07 GMT 5
The range assumes dry skull estimates (specifically McHenry's IIRC) to be underestimes by a factor of 2-3, so just do the same for the pliosaur and you've got your range.
Note though that those figures were based on sue, with some error bounds, so they apply to large specimens.
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Post by Grey on Aug 27, 2015 8:06:49 GMT 5
The range assumes dry skull estimates (specifically McHenry's IIRC) to be underestimes by a factor of 2-3, so just do the same for the pliosaur and you've got your range. Note though that those figures were based on sue, with some error bounds, so they apply to large specimens. So the results for P. kevani and Kronosaurus have to be multiplied 2 to 3 times ? I thought Foffa proposed some explanations regarding the peak bite forces and sustained bite forces, hinting that while conservatives these results are not vast underestimates. Also, we expect superior peak bite forces in the large white sharks and meg than what was presented in Wroe et al. 2008 ? |
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Post by theropod on Aug 27, 2015 16:12:37 GMT 5
Those are the factors coherentsheaf applied to T. rex estimates achieved using a comparable method, yes. I know Foffa et al. already applied a correction factor in some of their estimates (but a far lower one, at 1.5), but as you see, the in vivo measurements from Erickson et al. 2012 are still vastly higher (yes, as they explained that is likely also because they record peak forces) than the estimated figures for pliosaurus and crocodilians based on FEA or MDA.
I thought there was a study about the underestimates produced by the dry skull method in squamates, but I can’t seem to find it any more.
In any case what Foffa et al. clearly implied in their paper is that based on comparable methods, Pliosaurus bit about as hard as a crocodile with the same skull length.
I would assume that the computed estimate for sharks is also prone to underestimation, but I don’t know how much of this is reptile-specific and whether the estimate should rather be compared to the results from McHenry or those of Bates & Falkingham. It would be advisable to evaluate this further, e.g. a using a comparison of estimated and measured bite forces for sharks could help assess the amount of bias.
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Post by Grey on Aug 27, 2015 18:08:20 GMT 5
So Foffa and McHenry results are underestimates ?
Scaling from crocodilians, their results appear proportionally quite inferior in pliosaurs but this is related to the scaling body mass which réduces the relative muscle strength ?
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Post by creature386 on Aug 27, 2015 18:38:09 GMT 5
Reminds me of Richard Forrest's 5-15 t range for P. kevani. Multiplying Foffa's results by 2-3 times would fit nicely within that range. Though I have to say that this is not hard, given that the range is broad.
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Post by Grey on Aug 27, 2015 19:48:50 GMT 5
The 5-15 tons range he gave was from the jaws of life, not the pliosaur to which he gave 4-5 tons....the actual results from Foffa.
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Post by theropod on Aug 27, 2015 21:37:55 GMT 5
Yes, although I am not sure how precisely they can be compared (I’ll have to re-read McHenry some time). Scaling from crocodilians, their results appear proportionally quite inferior in pliosaurs but this is related to the scaling body mass which réduces the relative muscle strength ? Not sure I understand what you mean. |
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Post by Grey on Aug 28, 2015 2:11:51 GMT 5
I think I'll ask directly to Colin about the alleged underestimate.
What I meant is that while scaling from a smaller croc, the strength in the much larger pliosaur is proportionnally lower, like seen between a large white shark and large megalodon (bite force at 1.8 tonnes for 3.3 tonnes weight against bite force at 18 tonnes against 103 tonns weight, a large megalodon has a bite force proportionnally much lower than a large white shark).
This is the same observation between a Nile croc and P. kevani ?
Foffa told me this :
It's true that the supratemporal fenestra in pliosaurids is comparatively much larger than in crocs. But that's not the only factor. As you said the muscle volumes are hard to understand because some muscles groups exceeds the bone boundary (muscle pterygoideus in crocodiles - and we simply don't know this about pliosaurs). Other factors are the muscle lines of action which influence the efficiency of the biting.
So while the figure is conservative, is it really an underestimate...
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