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Post by Grey on Aug 8, 2019 19:56:42 GMT 5
...be more formidable and overall more powerful as a foe than would be in the same size range "the meg" and Livyatan.
Added to that, what is the chance for 15-18 m individuals to have existed at all ?
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Post by creature386 on Aug 8, 2019 20:13:18 GMT 5
I like the topic, reminds me so much of the founding days.
It would be a bit a lot less bulky at length parity though, wouldn't it? Ignoring that, I suppose the combination of shark-like dentition and crocodile-like bite force (OK, maybe not quite equal, but at least close) should let it outperform the competition at mass parity.
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Post by dinosauria101 on Aug 8, 2019 21:09:45 GMT 5
GreyIsn't the Monster of Aramberri supposed to be 15-20 meters or so? This may not be fantasy after all if that's the case. Anyhow, I think it would be THE most formidable sea creature; similar to what creature said, it combines crocodile skull size and bite force with shark dentition, and both seem to already have an edge over cetaceans at parity.
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Post by creature386 on Aug 8, 2019 21:16:13 GMT 5
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Post by Verdugo on Aug 8, 2019 21:29:51 GMT 5
At size/weight parity, i still don't think Pliosaur would be as formidable the Meg or macropredatory Cetacean, based on the research on their skull strength that i have seen.
These two independent researches came up with similar conclusion regarding Pliosaur's skull strength
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Post by dinosauria101 on Aug 8, 2019 21:31:12 GMT 5
It says I can't download the files.
That said...there is yet again another prehistoric giant downsized. Shame.
On another note, what about locomotion? I'm not sure who'd hold the advantage there, the pliosaurs or their counterparts. Could play a large role if it's significantly inferior in any of them.
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Post by Infinity Blade on Aug 8, 2019 21:36:36 GMT 5
To my knowledge the four flipper-powered locomotion of a pliosaur (and other plesiosaurs for that matter) would provide it with a maneuverability advantage over something with thunniform locomotion.
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Post by Grey on Aug 8, 2019 23:40:13 GMT 5
At size/weight parity, i still don't think Pliosaur would be as formidable the Meg or macropredatory Cetacean, based on the research on their skull strength that i have seen. These two independent researches came up with similar conclusion regarding Pliosaur's skull strength Yup but in terms of sheer biting force, I recall the analysis by Erickson for the Predator X doc predicted a 45 tonnes pliosaur would have a bite pressure of 15 tonnes. That is more than the 11 tonnes predicted by Wroe 2008 for a 48 tonnes meg. Bringing another question, could a 15 m pliosaur (first estimate for Predator X) really weigh 45 tonnes ? |
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Post by dinosauria101 on Aug 8, 2019 23:55:45 GMT 5
Bringing another question, could a 15 m pliosaur (first estimate for Predator X) really weigh 45 tonnes ? I'm a bit doubtful of that. Would a dimensional increase of only about 35 percent really result in quadrupling the weight? Maybe 30-35 tons is better |
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Post by Verdugo on Aug 9, 2019 9:50:57 GMT 5
Yup but in terms of sheer biting force, I recall the analysis by Erickson for the Predator X doc predicted a 45 tonnes pliosaur would have a bite pressure of 15 tonnes. That is more than the 11 tonnes predicted by Wroe 2008 for a 48 tonnes meg. I'm not aware of the paper (if there is) regarding the 15 tonnes Bite force of P.funkei. I suspect it was probably obtained by using regression based on in vivo data from modern Crocs. Anyway, i'm not sure about it, if you have the paper, please post it here. The only Bite force papers regarding Pliosaur Bite force that i know of are the two that i posted above. Both of the bite forces in the paper were obtained with the use of 3D FEA modelling. According to Foffa et al (2014)(1st paper in my previous post), the posterior bite force for a P.kevani with 2m mandible is 49000 N (range 28000-49000 N). According to McHenry (2009)(2nd paper), the posterior bite force for Kronosaurus with Basal skull length of 1.87m is 38000N   Since the bite force estimates from McHenry is right in the middle of the range of Foffa, i suppose this could give us a fairly accurate idea of the bite force of this animal. Feel free to extrapolate it to whatever hypothetical size you want. Foffa et al (2014) pointed out that the difference between their and McHenry's estimate was most likely to different out level (different tooth position when estimating the Bite force): "The values for P. kevani along the tooth row closely match those previously reported in Kronosaurus (McHenry, 2009); the differences (lower rostral and higher caudal values) likely arise from features such as snout length and outlever arm length (due to different positions of the most caudal bite position between the two taxa)"While Bite force is undoubtedly important for predatory purposes, Skull strength and shape seems to be a more determinant factor of predatory capabilities (if you use Crocodilian as a model). In Erickson et al (2012), they pointed out almost all modern Crocs exert lb 4 lb similar Bite force despite their differences in skull morphology and prey selection (with only 2 exceptions of this rule): "The results of our investigation into the biomechanics and evolutionary ecology of crocodilian feeding revealed a number of unexpected findings. We found negligible support for the commonly held view that bite forces correlate strongly with rostral form – a proxy for strength. Rather, bite forces vary independently of rostral morphology, so much so that in some cases same-sized taxa from the extreme bounds of crocodilian rostal morphology and dietary ecology (e.g. the slender-snouted, Crocodylus johnsoni and robust-snouted, Caiman latirostris; Figure 1) show “pound for pound” comparable molariform bite forces (Figure 3A). During cladogenic events, when rostral form was modified into different types (presumably to allow access to different prey), bite forces were just as likely to increase as decrease.
Our findings suggest that for crocodilians of similar body mass, the same absolute bite forces will be generated at equal distances from the quadrate-articular joint. A consequence of this is that more slender-snouted forms will at the same time experience higher stresses to their jaws since they have lower area moments of inertia with which to resist bending. Furthermore, since they have relatively longer snouts, equal loads applied at the tip of the jaws will lead to higher absolute bending moments than in shorter-snouted forms. This begs the question: How do slender-snouted species sustain bite forces typical of more robust-snouted crocodilians? We suspect the answer lies primarily in their prey selection. They target small prey relative to their size (e.g. fish and crustaceans, and/or birds and small mammals by the larger species) whose low inertia contributes little to resistance forces. It is also plausible that their jaws experience stresses closer to rupture strength (i.e. lower safety factor [24]) during feeding than the other ecomorphs. This is certainly the case during other behaviors such as fighting and defense, where they show a much greater propensity to sustain broken jaws [25]."Despite the Pliosaur having very high Bite force, their relatively weaker skull would indeed restrict their prey sizes (based on modern Crocs for ecology models), hence restrict their macropredatory capabilities when compared to the like of the Meg or Livyatan. Bringing another question, could a 15 m pliosaur (first estimate for Predator X) really weigh 45 tonnes ? McHenry provided an estimate of 10.5m long and 11 tonnes of body mass for Kronosaurus. If you scale it to 15m, you would get a body mass of 32 tonnes. The 45 tonnes is probably an overestimation. Anyway, regarding Pliosaur's bulk compared to Shark of similar length, i made a post on Carnivora before: If i use square-cube law to scale a 6 m 2 tonnes GW up to 10.5 m long, i'll get 10.7 tonnes. So it is around 11 tonnes like that of the Pliosaur here. It seems to me that a Pliosaur would weigh just as much as a Great white of similar length. |
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Post by dinosauria101 on Aug 9, 2019 9:52:10 GMT 5
VerdugoAren't larger pliosaurs proportionately bulkier than smaller ones? I was always under that impression
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Post by spartan on Aug 9, 2019 21:31:23 GMT 5
As far as I know the largest known pliosaur is P. macromerus with 19200kg at 12.7m. It's very unlikely that this specimen was the largest to ever exist, though. It's probably a given that were much larger ones at some point, but that can be said for every animal species that is only known from a few individuals.
Scaling from this a 15m P. macromerus would weigh about 31600kg.
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Post by Grey on Aug 10, 2019 0:22:22 GMT 5
Verdugo, there is no paper, that was just an independant estimate made by Erickson on a hypothetical 45 tonnes pliosaur.
I think their bulk model was quite on the upper end.
Anyway, this bite force at least gives us a hint of the region of the only real tetrapod macropredator that is known to have probably reached 45 tonnes, Livyatan.
I had read these indications of weak skull in pliosaurs but was always unsure of their relevance in terms of overall formidability.
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.
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Post by Grey on Aug 10, 2019 0:30:27 GMT 5
As far as I know the largest known pliosaur is P. macromerus with 19200kg at 12.7m. It's very unlikely that this specimen was the largest to ever exist, though. It's probably a given that were much larger ones at some point, but that can be said for every animal species that is only known from a few individuals. Scaling from this a 15m P. macromerus would weigh about 31600kg. Remember this estimate from the Cumnor mandible which is greatly overreconstructed. However I ve heard of a paleoartist, Andrew Cocks, who built a 2.6 m Pliosaurus skull model based on some pubis material that would indicate a 15 m animal. But this information is from Max Haxthorne blog, who is prompt to exaggerations with those beasts and may have overlooked some details. The bones are large but unsure if they fit in 15 m monster. I think I ve seen an estimate of rather 9 m. So based on this, even a 13 m pliosaur does not seem to be confirmed. But I m perfectly opened to the idea or 13 m or even 15 m monsters. But a 18 m one, this comes in the territory of the Neogene titans... I think the only professional researchers I know to admit pliosaurs in the 15-18 m range are David Martill and Frey and Stinnesbeck, who worked on the Aramberri big one. |
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Post by theropod on Aug 10, 2019 0:46:05 GMT 5
We are probably underestimating their maximum bite force, as other estimated made using the same method are consistently underestimates relative to in vivo measurements. This is acknowledged in both the relevant works and there are several potential reasons for this (unconstrained size of m. pt. ventralis, unknown degree of fiber pennation, difference between static and peak bite forces), as pointed out by Foffa et al..
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. Remaining differences in skull strength may have to do with differences in feeding behaviour (e.g. much of the excess robusticity in large crocodilians may be related to torsional feeding, which pliosaurs didn’t do). 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.
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