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Post by Infinity Blade on Nov 23, 2015 18:36:03 GMT 5
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Post by creature386 on Nov 23, 2015 20:24:50 GMT 5
As for the Tylosaurus depiction:
He can do that. I believe that Elasmosaurus would have a very small chance against Tylosaurus if we let them fight under the rather strict rules used in the AVA threads here and on carnivora. That doesn't mean that Elasmosaurus was not able to destroy the hunting success of Tylosaurus some times or even injure it so badly that it may never hunt again. Pleisosaurs were surely not COTD sauropods.
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Post by theropod on Nov 23, 2015 20:51:03 GMT 5
I also think obligate piscivory could be underestimating them, but what their skulls and necks were capable of needs further testing.
In any case, its jaws would have had to be able to withstand any force it hoped to excert on a prey item (trivial). Soft tissues and mobile parts can act as shock-absorbers to reduce unwanted peak stresses, but any force it actually wanted to excert itself (such as biting down or restraining a prey item) it would still have had to be capable of withstanding without yielding to reduce it. The FEA does imply that the skull was somewhat robust, that is true. But its neck won’t help it in that regard.
An even bigger question is whether the neck itself was strong enough to support inertial feeding, as that’d be the prerequisite of almost any form of large-prey acquisition by something with such a small head and long neck.
Some of the analogues aren’t all that relevant either, because none of them have a long or flexible neck, and in all of them the skull is considerably longer relative to body size. As Nash himself noted in the comments, when plesiosaurs developed more typical piscivorous skull morphologies, their skulls became longer, with neck length decreasing in exchange (e.g. Polycotylidae). The animal may not benefit from having a short AND gracile skull at the end of that neck, since that would lower prey size even further.
At one point Nash also seems to hypothesize an "increase in power and bite force" based on the enlarged temporal fenestra, whereas based on what he outlined earlier this also coincided with a decrease in the size of the pterygoid (which is very important in crocodiles, and potentially very important in pliosaurs), so that all it implies is that there wasn’t necessarily a decrease. Relative to skull size that is. What he doesn’t seem to consider is that the skull was also proportionately very small, unlike those of pliosaurs or crocodiles.
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blaze
Paleo-artist 
Posts: 766
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Post by blaze on Nov 24, 2015 1:59:23 GMT 5
I mostly agree with what theropod said above but just to drive further the point that Nash seemed to forget how small the skulls of plesiosaurs are, remember that the skulls of the largest elasmosaurid plesiosaurs were in the range of 40-50cm in greatest length.
I disagree with Nash where he disagreed with Araujo & Polcyn (2013), that the pterygoid musculature is more developed in crocodilians because of a need to conceal the head underwater, as argued by Pierce et al. (2009), the pterygoid musculature is just in a much better position to produce strong bites, its line of action being further away from the jaw joint has a greater mechanical advantage and produces slower but stronger movement than the same amount of muscle doing the same but in the supratemporal fenestrae area, crocodilians however appear to be unique in this regard because the secondary palette is an important anchoring point for the pterygoid musculature, Pierce et al. (2009) argue that since Thalattosuchians lacked a fully formed secondary palette and had relatively small pterygoid bones, they couldn't develop the pterygoid musculature to the level of crocodilians and were restricted to the faster moving but weaker and lower mechanical advantage supratemporal musculature, their solution to how produce strong bites was to ridiculously enlarge the supratemporal fenestrae and its corresponding musculature, I think it's reasonable to assume that similar constrains apply to other animals with convergent supratemporal fenestre development, like pliosaurs and plesiosaurs so no, crocodiles main jaw muscles are the pterygoid ones because by chance, they stumbled upon a much more efficient way of producing strong bites and it just so happened that it resulted in the corresponding musculature being shifted to be below the head, not because they needed to conceal their heads underwater (which ignores why are there horned crocodilians).
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Post by Infinity Blade on Jun 2, 2021 3:58:21 GMT 5
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