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Post by sam1 on Aug 22, 2019 18:50:34 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. I'd say Livyatan jaws and teeth were primarily of a gripp-and-tear type. Sure it could've simply crushed a smaller 5-6m prey, but for something larger, I see Livyatan just holding onto with those jaws and then deal massive damage channeling the body momentum force. |
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Post by theropod on Aug 22, 2019 19:49:49 GMT 5
Yeah, well, basically the answer is that nobody has studied it, that’s all there is to it. Crocodiles have a relatively similar skull shape subject to relatively similar ecomorphological selective pressures, and they have very similar bite forces at comparable skull lengths according to studies using the same methodology. T. rex has a completely different skull morphology; it skull is proportionately much shorter, but more voluminous, and its bite force was likely higher for a given skull length due to this. But also, using T. rex as an analogue would be pointless, as we can’t measure in vivo bite force for a T. rex. So if we want to use a taxon as an analogue that we only have estimated bite forces for anyway, why not use a pliosaur itself, as there are estimated bite forces for pliosaurs just as there are for T. rex? The problem is not that scientists "can’t simply calculate the force of the jaw closing muscles of Livyatan", it’s that nobody has done it so far. Research doesn’t just do itself over night because someone thinks "huh, that’s interesting", you need access to specimens, you need people with the relevant expertise, you need funding and you need time. I’m sure there must be ongoing research on the Livyatan holotype, but that doesn’t guarantee that someone has thought of and been able to study exactly those aspects of it that you find interesting. Regarding Basilosaurus, as I already wrote: The Basilosaurus estimate (Snively et al. 2015) is based on a combination of FEA and dry skull method.
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. |
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Post by Grey on Aug 22, 2019 20:20:12 GMT 5
I wonder if Stephen Wroe is working on Livyatan bite. He appeared in a tv doc where he briefly talked meg and Livyatan (no detail), so maybe he is at it. He already worked on Cenozoic mammals before.
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Post by sam1 on Aug 23, 2019 3:02:13 GMT 5
Regarding Basilosaurus, as I already wrote: The Basilosaurus estimate (Snively et al. 2015) is based on a combination of FEA and dry skull method.
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.Ah, alright, thanks. Got it, anyway I just feel it's a bit odd that the largest tetrapod bite hasn't been studied as opposed to so many less formidable ones. |
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Post by theropod on Aug 23, 2019 3:57:25 GMT 5
Yes, it certainly is, though it’s no less weird that no extant odontocete’s jaw mechanics have ever been studied either.
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Post by Grey on Aug 23, 2019 4:09:31 GMT 5
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Post by Life on Aug 24, 2019 23:33:45 GMT 5
IMHO, Megalodon and Livyatan are/were two of the most powerful macropredators to have ever existed.
Rest is noise.
If I need to pick one; Megalodon is/was the nature's ultimate killing machine.
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Post by dinosauria101 on Aug 25, 2019 9:28:19 GMT 5
1:Rest is noise. 2: If I need to pick one; Megalodon is/was the nature's ultimate killing machine. 1: What do you mean by that? 2: Wasn't Carcharocles chubutensis rather comparable in size? It may be a good candidate too |
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Post by creature386 on Aug 25, 2019 15:19:00 GMT 5
He means that the rest can't compete.
However, this thread is largely about a hypothetical pliosaur while Life was probably comparing Megalodon and Livyatan to real animals.
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Post by theropod on Aug 25, 2019 16:23:01 GMT 5
Yes, entirely hypothetical, no reliably known pliosaur seems to exceed 11-13m, whereas adult meg and Livyatan are pretty clearly in the 14-17m range. Everything we have discussed here is based on fictional pliosaurs of comparable sizes, which do not exist in the known fossil record.
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Post by Grey on Sept 3, 2019 17:26:39 GMT 5
I have heard the Aramberri material should have a final description in project...
What is your take on the largest, most powerful pliosaur taxa ?
I think Aramberri, Kronosaurus and or Sachicasaurus
I think Sachicasaurus has the second most impressive preserved macroraptorial skull after the Miocene killer sperm whale Livyatan.
This thing even has crown diameter up to 70 mm and a root at 90 mm in diameter. Something not seen so far in other pliosaurs and only in some large sperm whales.
The widest reptile teeth that I know of or at least very comparable to some T. rex teeth. Although I think I ve read about a 350 mm long T. rex tooth, which I guess maybe quite massive in diameter too.
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Post by dinosauria101 on Sept 3, 2019 18:05:38 GMT 5
GreyI could be incorrect, but don't most pliosaurs have larger heads/jaws in relation to size than sperm whales/Livyatan?
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Post by Grey on Sept 3, 2019 19:48:14 GMT 5
Definitely.
Sachicasaurus, if it was 11 m while complete, would have a ratio 1:5.
Pliosaurs were essentially swimming giant jaws. Theropod hinted at something interesting, that their body size could have been limited by the sheer power of their skull.
If Aramberri or Sachicasaurus were around 15 tonnes in body mass, they would have had a posterior bite force as high as what Wroe calculated for a 48 tonnes Otodus.
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Post by dinosauria101 on Sept 3, 2019 19:49:12 GMT 5
That's very interesting!
I'd think a 20-25 ton pliosaur would be needed to match Megalodon's bite if that holds true
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Post by theropod on Sept 3, 2019 21:41:50 GMT 5
Well, I was actually talking along the lines of their giant jaws in comparison to body size removing the need for the body to grow larger. Whatever studies based on the jaw mechanics have more or less suggested (weak skull etc.), there are pliosaur bite marks suggesting they preyed, or at least fed on 5-20t Leedsichthys, the biggest marine animal we know from that time. As you all know, maximum size of animals depends on a whole range of intrinsic and extrinsic factors. For a herbivore, larger size means greater security from predation, but for a predator, it means access to larger prey. If a predator is already capable of preying on the largest potential prey in its environment, that can be a factor stopping it from growing even larger. Not the only factor to consider, but one of them. Not really related to this, plesiosaurs have a style of locomotion completely different from all other giant marine animals, which means intrinsic factors related to locomotion could be very different to those in axial swimmers, which are all shaped by strong convergence in this regard. This by itself could either mean pliosaurs were limited to smaller sizes, or could theoretically grow to larger sizes, and we do not know whether this is the limiting factor to actually affect them. @dinosauria: What, he just wrote 15 tons in the very same post you are referring to! Grey: That being said, scaling up Sachicasaurus based on P. kevani (= comparable methodology to Wroe et al.) based on midline skull length gave me 62kN, so that’s not quite as high as the 48t meg (109kN). If we use other skull measurements (2.52m pmx-q gives 77kN), which are comparatively larger in Sachicasaurus but not so much in P. kevani, we can get higher values, but not that high. |
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