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Post by Grey on Jun 16, 2013 14:53:22 GMT 5
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Post by theropod on Jun 16, 2013 14:53:25 GMT 5
How do you know? were there teeth found? Otherwise it is impossible to tell after it is healed. Obviously, ?ike you argue yourself, cetaceans don't all have the same body. The size of the ribcage, as you can clearly see in the orca/livyatan comparison, has significant impact on the neck shape and of course the shape of the overall animal. Without it, the reconstruction of these parts is speculative. What I do know is that even Brygmophyseter with tis tiny postcranium seems to indicate a larger ribcage depth than cranial depth, which is not shown in that reconstruction. It probably focuses entirely on the head. Regardless of the reliability, those articles do not give any precise figures. I couldn't agree more with your last sentence. like this camarasaurus ilium from Chure at al., 1998: lh6.googleusercontent.com/-UwPQqV0BS2k/Ub25Kmd4JuI/AAAAAAAACEA/6c2XK7QIVZM/w630-h604-no/camilmarks.jpgBig bones deeply damaged, not cut through, not the bite marks of an animal that kills by damaging them but of one that attacked the soft tissues on them. period I am not the one who insists on debating this. For me the situation is pretty clear until I see evidence. PS: Trying to watch that video, but it doesn't work for me at the moment. I had overlooked the link before.
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Post by Grey on Jun 16, 2013 15:01:29 GMT 5
How do you know? were there teeth found? Otherwise it is impossible to tell after it is healed.
How do I know what ?
The shark was reported 4-8 m and the balaenopterid at around 15 m. I don't have the source at hand.
I know there are differences, I (and Lambert speak about the basic body plan). The skull is determining. Check the Nature video.
This is you who's speculating there.
Bring me an evidence that raptorial sperm whales were more built like orcas please.
You'd prefer the shape of the head to be more orca-like I guess ?
You have evidences since yesterday, you did not check the video yet. No the truth is that you just don't want to accept it. I recognize some of your points valid or interesting but I see also your tendency to interpret words in a way transforming the feeding apparatus of megalodon for what it is not recognized. Same with Livyatan skull shape. You now say that the reconstruction by Lambert et al. is speculative...because you prefer your own interpretation as a giant orca-like built odontocete.
You're educated but hardly want to admit when you are, at least partially, wrong. No personnal offense don't worry.
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Post by Grey on Jun 16, 2013 15:13:07 GMT 5
The huge baleen whales vertebras he talks about are from Pliocene deposits of Aurora BTW.
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Post by creature386 on Jun 16, 2013 15:31:56 GMT 5
How do you know? were there teeth found? We know the size of the bite mark and therefore can guess the tooth width. Using the tooth width method, I estimated its length at a bit more than 7 m.
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Post by theropod on Jun 16, 2013 15:45:32 GMT 5
Even under the premise that from a healed bite mark (and despite the difficulties caused by the unknown angle at which the teeth scraped across the bone) one could estimate the attacker's size reliably, what does this change? And you tell me not to speculate? It unfortunately doesn't work, before that, I had tought it just belonged the toe speech below it. Or it is the other way around. Who said that? You are interpreting my words the way you want. I don't even interpret in this case, I'm looking at the facts, which are that the postcranium of Livyatan is not known. The proportions between cranium and postcranium can obviously vary a lot, that's the cause for the difference in the two reconstructions, which seems to assume a strict physeter-like body plan for Livyatan, even tough it is morphologically and ecologically completely different. No need to automatically call everything differing from a longirostrine suction feeder orca-like, even tough I never understood why everyone is so arguing so firecely against similarities between Livyatan melvillei and O. orca, which obviously exist. The feeding apparatus is not properly described, the sources in this case are vague. The majority of bite marks clearly support my view, hence it it probably you who misinterprets them, not me. Also, isn't Livyatan "more direct and brutal" by your own phrasing?
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Post by Grey on Jun 16, 2013 15:57:56 GMT 5
It is estimated in size by Godfrey. Read the paper please before talk. This changes that the whale was much larger than the shark, probably a juvenile meg. No wonder it did not bite though the bones. But it proves the level of agression in these sharks.
Hum...yes ? I ask you if you'd prefer to have Livyatan as a badass orca-like head structure instead of a boring sperm whale apparata.
Surely you lack a plugin for visualize the video. Mike Siversson describes physically the size of the vertebras cut through in Aurora.
Megalodon could bite through any kind of bones in balaenopterids.
Check the Nature video (again). The skull is the one of a sperm whale, they do not need the remaining body to know where to place flesh, muscles and skin. The links between orcas and this physeteroid is ecological, not morphological. No one, not even the guys in the team, has ever suggested an orca-like body. That's your idea. And frankly, I don't care of it. I rely on the actual facts me too. The actual facts is that this is a sperm whale-like head.
The bite marks are known to have let deep gashes in large bones, some even bitten in half. No, you just don't want accept that.
But okay you're right. Livyatan was built more like an orca and C. megalodon couldn't bite through large bones. Happy ?
No more discussion with you awaiting more stuff on that matter.
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Post by Life on Jun 16, 2013 16:27:45 GMT 5
How do you know? were there teeth found? Otherwise it is impossible to tell after it is healed. Here is the source: www.eurekalert.org/pub_releases/2011-11/s-doa111011.phpA scientific paper have also been published about this event. The event confirms that megatoothed sharks were very aggressive and dangerous. The fact that this juvenile managed to tear through all that flesh and blubber and got to the rib cage of such a big whale, is testament to incredible potency of its killing apparatus. This whale died after some weeks, if I recall correctly; probably infection developed? Another example of cut marks from a juvenile (different whale; different event; different shark): Obviously, ?ike you argue yourself, cetaceans don't all have the same body. The size of the ribcage, as you can clearly see in the orca/livyatan comparison, has significant impact on the neck shape and of course the shape of the overall animal. Without it, the reconstruction of these parts is speculative. What I do know is that even Brygmophyseter with tis tiny postcranium seems to indicate a larger ribcage depth than cranial depth, which is not shown in that reconstruction. It probably focuses entirely on the head. Actually lot of bones found contain wounds inflicted by juvenile Megalodon and/or adult Giant Mako. In addition, larger the shark, more damage it would have been able to inflict during attack. Furthermore, a 17 m long Megalodon may have went after the rib cage section of a whale of comparable size; just one bite would have sufficient to inflict mortal injuries to even such a big whale. Therefore, without a holistic picture, these records may confuse people. I couldn't agree more with your last sentence. big bones deeply damaged, not cut through, not the bite marks of an animal that kills by damaging them. period Most of these specimens have been found partially preserved with large chunks of their bodies missing; presumably eaten. In some cases, skulls have been missing and in some cases whole caudal regions. Of-course, if a single Megalodon attacked a whale of comparable or larger size, it would not have been possible for it to consume the entire animal by itself after killing it. It is also possible that Megalodon drove some of its victims to breaching while attacking it; therefore loosing access to the prey in the process. Huge Megalodon much more commonly lurked in the considerably deep waters where they could afford to have element of surprise; their epic kills may not have ended preserved most of the time (fossilization itself is a rare process) and the victims may have been mostly eaten by them, leaving little traces behind. Therefore, we have to focus on the holistic picture to understand what is going on. Hope this clears the confusion. Here is a decent example of what could be left of a whale, if a huge Megalodon attacked it: This shark went straight for the rib cage section; only a partially preserved bone from the victim's pectoral fin have been found. The rest of the animal is gone. This bone may have flown off from the main body during the impact of the initial attack.
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Post by theropod on Jun 16, 2013 16:36:03 GMT 5
Again, what I doubt is not the potency of C.megalodon's killing apparatus, merely the supposed ability to cut through large bones. The flipper bone in the video is a nice example of this, it shows cut marks, as if the shark attacked the appendage to disable the musculature and tendons and possibly cause a heavily bleeding wound. Arguably a bite to the ribcage would lead to pretty quick death in any case, I totally agree here. I just point otu to different killing styles in Livyatan melvillei and C. megalodon.
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Post by Life on Jun 16, 2013 16:40:34 GMT 5
I agree with the slicing analogy though lateral shaking activities may have resulted in damage being inflicted in different forms as I previously revealed with examples a few posts back.
Keep in mind that Megalodon had no trouble carving and cutting through the bones of its prey depending upon its size and its prey size as well. Huge ones would have ripped apart almost anything without much trouble.
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Post by Grey on Jun 17, 2013 15:25:31 GMT 5
Of course, megalodon is a slicer or a sawyer. Brett Kent has a non-published manuscript where he hints that megalodon teeth were more strongly anchored than the teeth in the white shark. Megalodon was a robust slicer or gousher.
At first it was made at slashing the flesh but it evolved to be able to damage even internal parts protected by bones, something that a white shark cannot do. I have yet to see any inference about its limitation at biting through any large bone. Mike Siversson described huge vertebras in the video linked above.
Its teeth are very sharp and very robust, adapted to survive impacts against bones (Kent 2013). It is obvious that this does not imply small bones, as anyone, inluding myself, can bite through small bones...
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Post by theropod on Jun 18, 2013 0:21:21 GMT 5
Nothing of that is surprising. I think the conclusion that C. megalodon could bite through any bone it wanted to is wrong, that's all. What we mostly see of it is not too different from this or what you can see described here. That C. megalodon due to its size and power as well as impact-related forces would have had the capability to heavily damage even large prey, leading to quick death, is out of the question, but its means of doing so was not primarily an attack on the bones, something it clearly is not specialized in, merely suited top some extent. I already noted at least in part the tooth robusticity in sharks may be allometric to make up for decreasing strenght relative to mass(=inertia, especially important in impacts on prey items as those known in sharks). I have yet to see examples of evidently huge bones being bitten through, the majority shows scratchmarks, not unlike those seen in some examples from the Jurassic Morrison Formation, but I'll check the video the next time I'm in Windows, there it might work. Besides, it is not true regarding attacks on bony regions it is that different from the great white (or as I already showed from other slicers), Carcharodon carcharias has been recorded preying on seaturtles, which necessitates attack on a rather robust ribcage. Not saying C. megalodon could not do this better than it, neither am I saying it did not btie through large whale's ribcages. But I have absolutely no reason to believe its bone damaging potency was comparable to that is a crusher, otherwise why would any animal have different morphology from this all-round killer? As I said, payoffs. You cannot be both a super-effective slicer AND crusher/bone-slicer. The white shark Also has been repeatedly recorded slicing off human limbs, which given the typical size of Carcharodon and the comparative size of a human femur, humerus or tipiotarsos is quite an impressive demonstration of bone-slicing. Not that different at all, merely a bit different in the emphasis and attack style.
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Post by Grey on Jun 18, 2013 6:36:40 GMT 5
In all the examples provided there's not uniquely scratch marks but deep gashes in large bones. Yes, it was mores specialized at biting through bones given its teeth much more robust and thicker than those in extant macropredatory shark. When you have teeth that robust and large and a bite force in excess of 10 tons conservatively, you can bite through bones. Allosaurs did not were abe to decapitate something as big as cetothere compared to a megalodon and I've yet to see any allosaur biting in half a thick whale bone. The bones provided above are large and the ones in Aurora described by Siversson in the video seem huge. The sea turtles example is not wise. White sharks don't crush or slice through sea turtles : The occurrence of marine turtles in the diet of white sharks,Carcharodon carcharias, is reviewed worldwide. Four records of chelonians eaten by white sharks in the Mediterranean Sea are described, which on the basis of carapace remnants con?rmed both the loggerhead Caretta caretta and green turtle Chelonia mydas to be preyed upon in those waters. The condition of these remains indicates that large white sharks can ingest turtles essentially intact.Predation by white sharks Carcharodon carcharias(Chondrichthyes: Lamnidae) upon chelonians, with new records from the Mediterranean Sea and a ?rst record of the ocean sun?sh Mola mola (Osteichthyes: Molidae) as stomach contents Ian K. Fergussona; Leonard J.V. Compagnob& Mark A. Marks We are talking about comparisons in large sized mammalians preys and in the case, megalodons and white sharks are different. Your line : Kent (2013) : The bite marks are concentrated in the thoracic region, rather on the flanks where the large swimming muscles are present. Based on biomechanical principles, predatory strikes on prey should be directed at the center of mass, as this is the most predictable target on the preyÂ’s body. For piscoid prey this corresponds to the deepest portion of the body, about one-third of the body length from the anterior end (Webb and Skadsen, 1980; Webb, 1984). This matches the highest concentration of bite marks on the whale skeleton, and is consistent with this predicted attack strategy. This region contains numerous visceral organs, such as the heart and lungs, and a bite in this area would quickly subdue the prey. But the thoracic viscera are also protected by numerous rib and forelimb bones which could deter attacks and protect vital organs. The teeth of C. megalodon are particularly robust and appear adapted for surviving impacts against bones (Farlow, et al., 1984; Kent, unpubl. data). This apparent attack strategy by C. megalodon is very different from the placement of attacks by the extant C. carcharias, which avoids this area in cetaceans and instead attacks other body areas, especially the caudal peduncle. This area has major blood vessels, the spinal cord and swimming muscles, and damage to this area would quickly disable the prey (Long and Jones, 1996). This is a very efficient attack strategy, but the caudal area of cetaceans would be a less predictable target than the center of mass and would require more rapid neuronal processing in the brain to be successful. Lamnids are known to maintain elevated brain temperatures, which would facilitate their ability to track the complex movements of the caudal area during an attack (Bernal, et al., 2012).Megalodon and white shark are different. What has to do the human in this ? A human weighs 75 kg with a gracile bone constitution. A white shark weighs typically in excess of 1 000-1 500 kg. No big deal it can dispatch a human prey. Kent is comparing both large mammalian preys in both predators. For the last time, I don't say that megalodon was a typical bone-crusher. I recall you that when you're one of the largest marine predators in history and that even the largest prey-items in the sea couldn't dwarf you, when you're armed with teeth more robust and more strongly anchored than in any other shark and with a bite force perhaps between 10 and 18 tons, yes, you can bite through any bones of any prey. Which does not mean it obligatory did this as its sharp teeth were primarily made at slashing through big blubber.But simply when you have this as teeth and a huge bite force because of your great size, you can bite through or deeply penetrate any bone.
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Post by elosha11 on Jun 18, 2013 9:51:27 GMT 5
Here's what I would call an impressive example of bone crushing by Megalodon. From elasmo.com "The below images are distal and proximal views of a portion of a large whale rib from the Yorktown formation which had apparently been bitten clean through by a large shark (probably Carcharocles due to the size of the teeth imprints). An particularly impressive feat considering that the bone is 25mm (1 inch) thick. The top of the distal image shows the impact of two of the wide upper teeth. The top of the proximal image shows the impact of three of the narrower lower teeth. I have observed similar damage to two other rib bones (including another one from Lee Creek). Of particular interest is the spacing of the apparent bite marks which indicate that the teeth of Carcharocles (if he was the culprit which appears likely to me) are set closer together than those of Carcharodon, thus the jaw and overall size may be somewhat smaller than estimates based on scaled up Carcharodon jaws. The bone shows possible evidence of partial digestion. The bone may have been swallowed, partially digested and then later regurgitated (a common occurance with sharks)."
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Post by Grey on Jun 18, 2013 10:35:49 GMT 5
Here's what I would call an impressive example of bone crushing by Megalodon. From elasmo.com "The below images are distal and proximal views of a portion of a large whale rib from the Yorktown formation which had apparently been bitten clean through by a large shark (probably Carcharocles due to the size of the teeth imprints). An particularly impressive feat considering that the bone is 25mm (1 inch) thick. The top of the distal image shows the impact of two of the wide upper teeth. The top of the proximal image shows the impact of three of the narrower lower teeth. I have observed similar damage to two other rib bones (including another one from Lee Creek). Of particular interest is the spacing of the apparent bite marks which indicate that the teeth of Carcharocles (if he was the culprit which appears likely to me) are set closer together than those of Carcharodon, thus the jaw and overall size may be somewhat smaller than estimates based on scaled up Carcharodon jaws.The bone shows possible evidence of partial digestion. The bone may have been swallowed, partially digested and then later regurgitated (a common occurance with sharks)." That's interesting, it proves that Carcharocles remains a very mysterious species. That's why I rely on the rigorous reconstructed jaws but I always recall that it's one possible interpretation but not necessary the absolute truth. But I see that nothing substantial has been written from that suggestion of Heim. I quote one of the private informations by Bretton Kent : Jaw shape is a bit problematic. In lamniforms it can be relatively long and moderately broad (whites and makos) or relatively short and quite broad (threshers). It seems to me that short, broad jaws are typically associated with smaller prey, and so would be unlikely for megalodon.But how verify it ? I'd discuss it with Kent...
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