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Post by prehistorican on Jul 11, 2018 17:19:56 GMT 5
Well if that is your opinion that's fine. I just imagined it as a predation event by a possible large Meg on a smaller macropredatorial whale morphologically similar to Livyatan. Based on fossil evidence, we know that Megalodon could attack the jaws and skull of whales so why not a far smaller (even though quite raptorial one). That is my opinion, and I gave some reasons and and I even admitted that it very well could be wrong. Most likely, even though not by such a large margin, I believe this is a predatory event.
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Post by prehistorican on Jul 11, 2018 17:24:48 GMT 5
Prehistorican, You may very well be correct that the fossil tooth in question is from a Livyatan, representing the "C" position in the holotype. The longest holotype teeth were 36 cm, and it looks like to me that the tooth in the C position looks to bearound 30-31 cm, but that's just a rough guess. I believe there is published, publically available descriptions of the holotype that may give the length of the C positioned tooth. I have no idea of how the growth rate of the teeth would assist in predicting the body length of a Livytan, but at 21 cm v. 30-31, it would need to be significantly smaller than the holotype. If the holotype was 16 meters, as you postulate, 11-13 meters is not an unreasonable estimate of the Livyatan with the bitten tooth. But again, we should be cautious since there are multiple layers of assumptions built into such a conclusion. And of course, there's simply no way to determine whether the Megalodon was predating the whale or scavenging its carcass. Although you have made me less certain this was prehistoric sperm whale, rather than a subadult Livyatan, it's still a bit unknown. Here's a somewhat similar tooth, that's called a prehistoric sperm whale, but may have very well be a Livytan-like whale rather than a traditional sperm whale. i.pinimg.com/originals/c9/f4/66/c9f466d1c7485ed158c2de2911222283.jpg That's a Zygophyseter, quite easy to see in the tooth shape itself. But not as straight and similar shaped as the shark bitten fossil tooth similar position to "C" in holotype Livyatan jaw. |
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Post by prehistorican on Jul 11, 2018 17:51:54 GMT 5
I believe that the normal "Megalodon vs Livyatan" interactions are *almost* never between adults of each species, that would cause too much damage towards both and they would know it. I'd suggest that these interactions are likely adults of the species, preying upon the young of another. Ex: Livyatan sneaks into a shallow nursery to catch a Megalodon pup. In my opinion, I believe this is most likely vice versa. Sperm Whale bitten tooth suggestions: 1: Feeding Frenzy 2: Misstrike 3: Scavenging 4: Predatory Attack Based on the multiple slash marks, I speculatively interpret the intial deep slash mark on the tooth as a depth strike from below. This is the first major bite mark, and is at full force coupled with the shark's speed+body mass which makes a deep mark on the tooth. As it slightly ascends, the whale slips down slowly further in the Meg's jaws. The bite marks get slightly placed higher with each bite as the shark is trying to readjust its jaws since it is bitting into something very bony. Remember the Deep Blue video? Biting down onto a metal pole, the pole was a hard object and trying to readjust her jaws since she wasn't used to it. This makes me more inclined to believe that Theropod may be right in saying that it was a mistrike. youtu.be/JlpNooty0io6:00-6:12 |
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Post by elosha11 on Jul 11, 2018 23:55:25 GMT 5
Well if that is your opinion that's fine. I just imagined it as a predation event by a possible large Meg on a smaller macropredatorial whale morphologically similar to Livyatan. Based on fossil evidence, we know that Megalodon could attack the jaws and skull of whales so why not a far smaller (even though quite raptorial one). That is my opinion, and I gave some reasons and and I even admitted that it very well could be wrong. Most likely, even though not by such a large margin, I believe this is a predatory event. Were you replying to one of my posts? I definitely agree this could be (1) a predation, (2) a scavenging event, or (3) a conflict of some kind in which neither animal was killed. Given some evidence that Megalodon was not shy about attacking the head region, (e.g., fossil whale in Sharkzilla) it certainly could have been a predatory behavior. Unfortunately, the fossil evidence can only carry us so far. |
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Post by elosha11 on Jul 12, 2018 0:02:38 GMT 5
I was just reading through this thread and find it very reassuring that only one poster("prehistorican") is showing bias, while Theropod is saving me the trouble with points I would've brought up in response. I'll just note that, to me, this whole forensic speculation saga is, while interesting, kind of silly as there is no doubt that these animals have killed each other on countless occasions throughout their co-existence. No need to prove or disprove it, it's just common sense and the law of probability. We can discuss and speculate about how probable and frequent the attacks were, but again, there's no doubt that they were happening. I'll note that this thread's purpose is not to "prove or disprove" that large sharks preyed on cetaceans or vice-versa. But in examining the different bite marks on different sized bones from different species, we're able to glean some valuable but limited information as to how/when these animals were interacting. Occasionally, we even come across the very interesting sign of healed bones, a tell-tale sign of a predatory interaction, or something as unusual as a shark bitten physteriod tooth. Speculation it may be, but such clues are tantalizing and it's pretty fun (and somewhat educational) to surmise just how it went down |
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Post by theropod on Jul 12, 2018 1:54:18 GMT 5
And especially, the purpose of this thread is not to discuss Livyatan vs Megalodon. I propose that aspect should be moved to the appropriate thread (there are certainly a few claims I’d be thrilled to see more evidence of presented there, and perhaps a proper citation once in a while…) and this one to strictly focus on identifying and describing bite marked bones. And we should all should try to make ourselves concious that bite marks are pretty much never a clear evidence of predation as opposed to scavenging or vice versa, at best vaguely indicative. Grey: I actually did find an osteological description of a sperm whale, and one newer than the 19th century at that, but sadly all the figures of the vertebrae somehow went missing: eprints.cmfri.org.in/572/1/Article_20.pdfAnyway, it seems the anteriormost two caudals shouldn’t have haemal arches, so the first vertebra (the one elosha posted) might also be one of the anteriormost caudals, but I’m still leaning towards (posterior) lumbar. Without the neural spine and zygapophyses (if present) being preserved, it’s hard to tell for sure. But with what remains of the neural arch being so narrow, the zygapophyses must have been fairly narrow if they were present, so it can’t have been too far anterior in the collumn. Your centrum looks more like an anterior caudal to me. At least it does have that hole at the margin of the ventral surface. I don’t have a sperm whale skeleton at hand to compare it to, but off the top of my head the only thing I can think of is that being part of where the haemal arch attached |
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Post by creature386 on Jul 14, 2018 3:37:00 GMT 5
And we should all should try to make ourselves concious that bite marks are pretty much never a clear evidence of predation as opposed to scavenging or vice versa, at best vaguely indicative. What about healed ones (which are not rare)? |
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Post by elosha11 on Jul 14, 2018 3:58:01 GMT 5
Are they not rare? I only recall two examples of clear cut healed bones in this thread, the oft cited healed baleen rib bone found by Godfrey and another caudal bone from a museum that I posted on this thread, but which unfortunately no longer has the picture available.
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Post by theropod on Jul 14, 2018 4:36:29 GMT 5
creature386: Good point, I was not including healed injuries even though they are also bite marks. I meant bite marks as in trace fossils, excluding palaeopathologies. I think that yes, healed bite marks are pretty solid evidence of predation*. The problem that they present is that it can be very difficult to match the pathologies up with the right attacker, and that they necessarily represent traces of unsuccessful predation (so of limited use if we want to argue about what a predator could or did actually kill). But certainly useful, especially in combination with (post-mortem) bite marks. I just wished there were more examples of this. *Including "flesh-grazing", as may have been the case with Kallal et al.’s whale rib. Let me reiterate that I think distinguishing between "flesh-grazing" and failed predation is meaningless, given the attacker is at least theoretically capable of causing fatal damage to the victim.
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Post by Grey on Jul 14, 2018 19:12:03 GMT 5
I'm skeptical of the flesh-grazing theory of the Kallal et al. case.
To my knowledge, such a feeding behavior has never been observed in any pelagic macropredatory shark.
An unrealistic predation attempt is the simpler and more likely explanation to me.
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Post by theropod on Jul 14, 2018 20:08:51 GMT 5
^That is the point, there’s no difference between flesh-grazing and an "unrealistic predation attempt".
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Post by elosha11 on Jul 14, 2018 21:14:05 GMT 5
^Can't agree with that in general. There's a difference in outcome, and a difference in intent. To use the analogous shark flesh grazer, a cookie cutter shark's "intent," as it were, is not to kill its target, it's more parasitical in nature and its intent is truly to feed on small divots of flesh it bites out of its huge host targets. It's not an "unrealistic predation attempt," since the flesh graver has no chance whatsoever in killing or even seriously injuring its "prey." The cookiecutter shark is undertaking the natural and specialized feeding behavior for which it evolved. Whereas a 4-8 meter juvenile mega-toothed shark is far less likely to have such a grazing "intent" in attacking a much larger baleen whale. Its predatory behavior is evolved to kill, not to flesh grave. And of course, comparatively speaking, the attack on the whale in the Kallal case caused damage far more significant than what a typical flesh graver would do. A cookie cutter shark merely removes a plug of blubber, leaving an unsightly scar, but not a serious injury. This shark however, bit the whale down to the rib bone and damaged the bone itself. It likely removed a large chunk of blubber and flesh, leading to blood loss and possible infection. It could have been a significant injury and probably contributed or even led to the whale's death several weeks later.
I'm not saying it's impossible that this shark could have been intentionally flesh grazing, albeit with far more serious consequences for the target. But as Grey says it's not something we see in modern day apex predator sharks. I'm more inclined to see it as an overly ambitious predatory attack, which may have still been successful for the shark in that it got at least one large mouthful of nutritious whale blubber.
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Post by theropod on Jul 15, 2018 3:23:19 GMT 5
As I wrote: "given the attacker is at least theoretically capable of causing fatal damage to the victim"
I do recall a video of a tiger shark feeding on a sick blue whale, and I do think that qualifies as flesh-grazing, as the attack did not directly lead to the animal’s death (although it probably contributed, just like Kallal et al.’s bite mark), yet involved the shark feeding. If we call false killer whales taking bites out of sperm whales "flesh-grazing", then we should certainly call that, and the bite mark on the rib. and pretty much anything where a large predator takes bites out of its prey without killing it "flesh-grazing". Hence why I think it’s not objectively distinguishable from predation. Cookie-cutters on the other hand do qualify as different, because a cookie-cutter parasitises animals that are far too large for it to ever be able to seriously harm.
The point is that the only possible difference is in practice, meaningless, as long as you can not read the thoughts of the animal to determine whether its "intent" (if it even had one) was to kill, or just to take a few bites. But we can’t read the thoughts of extant animals, and certainly not of extinct ones. The only thing that is observable is the actual behaviour, which isn’t really qualifiably different, or, in the case of fossils, the end-result; a healed bite mark.
If all we have is a piece of bone with healed bite marks, all it tells us about the predation event is that the animal was bitten, but not killed. If we break it down, that’s the definition of "flesh-grazing". If you want to redefine the term to only apply to harmless parasitism by small predators, I’ve got no problem with that. But I’ve heard the term being applied to (hypothetical) large theropod feeding behaviour on sauropods, and to attacks by Orcinus and Pseudorca on large whales, so as long as it is used in this manner, it remains a form of predation.
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Post by Grey on Jul 15, 2018 14:32:28 GMT 5
^That is the point, there’s no difference between flesh-grazing and an "unrealistic predation attempt". I get what you mean. But there is a difference in the intentional nature. Flesh-grazing is a mean of feeding, the agressor having no intention to kill the larger prey items, such as cookier-cutters and apparently false killer whales. This is not observed in large pelagic sharks to my knowledge. An attack on a large prey items is always in the attempt to kill it. |
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Post by theropod on Jul 15, 2018 17:00:49 GMT 5
Once again, how do you determine the "intent" of an extant predator, let alone an extinct one, if the outcome is the same? How can you claim to know the thoughts of an odontocete or shark? See my last post; I certainly think the behaviour of a tiger shark, which is an apex-predatory shark, does qualify as "flesh-grazing" (because of the results of the interaction, but even by the standard of "intent", I do find it hard to believe that it approached the blue whale with the concept of killing it in mind), but you may not agree with that assessment…
A predator might even enter an interaction with the "plan" to kill, but then change its mind and content itself with a few mouthfuls of flesh. Is that predation, according to this logic (the original intent was to kill, after all), or is it "flesh-grazing"? It’s really anyone’s guess, seeing as we would have to be a telepath who can actually observe thought patterns in order to determine the actual intent (which is itself an oddly human concept when talking about the thoughts of an elasmobranch, who knows what goes on in a shark’s brain when hunting?) behind an attack.
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