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Post by Grey on Apr 22, 2016 18:08:30 GMT 5
Extremely interesting. It seems like either Livyatan or a very similarly sized raptorial sperm whale lived into the Pliocene. If this tooth is Livyatan, it also suggest the species was capable of trans-Pacific travel, as it is about a 15,000 km straight trip from Peru (where Livytan skull was found,) to Australia, where this tooth was found. And given the migratory habits of Livytan's presumed cetacean prey, it makes a lot of sense that it would a pelagic species, and not one inclined to only South America. The tooth looks extremely similar to Livyatan's, and in fact given its robustness and length, which far exceeds that of other known raptorial sperm whales, I'm inclined to believe this is another example of the Livaytan soecues. The 18 meter length and claims that it was still growing are both speculative and likely an exaggeration, made in the excitement of the discovery. A larger 36 cm tooth associated with the whole Livyatan skeleton yields a 13.5 - 17.5 meter range, so a smaller 30 cm tooth should not yield a larger size estimate. Nor can I figure out why the scientist quoted states it was 18 meters long and still growing, unless he's accounting for the fact that larger Livytan teeth have been found. But in that case he should have clearly stated he believes this to be a Livyatan tooth and said that this animal was likely a bit smaller than the published range of the holotype. If he wants, he could then surmise that the species might reach up to 18 meters. It always annoys me when scientists themselves make exaggerated or sensationalized claims to make their discovery more impressive. To me, the size isn't the most impressive part, although it does suggest a quite large Livyatan. The most exciting thing is that it shows Livyatan likely lived longer than what was previously predicted (and may have become extinct from the same factors that doomed Megalodon) and that it suggest that the species may have covered a far greater territory than previously thought. I would be inclined to put these articles in the Livyatan profile thread, but perhaps that is a bit premature. The tooth is 30cm but somewhat incomplete, so it is possible it was closer to the biggest teeth in the Peruvian whale. I think the immature statement possibly comes from the growth curve in the tooth if viewable. And there is always the possibility the tooth isn't the largest of the dentition. I've briefly discussed with the paleontologist, he says the size analogy is (obviously) based on Livyatan estimated size, noting it could be immature, so it was scaled to 15m. My understanding is that 18m would represent the adult size. The tooth will be studied anyway. I think they tend more to think it is a closely related species to Livyatan. |
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Post by elosha11 on Apr 22, 2016 18:19:52 GMT 5
Extremely interesting. It seems like either Livyatan or a very similarly sized raptorial sperm whale lived into the Pliocene. If this tooth is Livyatan, it also suggest the species was capable of trans-Pacific travel, as it is about a 15,000 km straight trip from Peru (where Livytan skull was found,) to Australia, where this tooth was found. And given the migratory habits of Livytan's presumed cetacean prey, it makes a lot of sense that it would a pelagic species, and not one inclined to only South America. The tooth looks extremely similar to Livyatan's, and in fact given its robustness and length, which far exceeds that of other known raptorial sperm whales, I'm inclined to believe this is another example of the Livaytan soecues. The 18 meter length and claims that it was still growing are both speculative and likely an exaggeration, made in the excitement of the discovery. A larger 36 cm tooth associated with the whole Livyatan skeleton yields a 13.5 - 17.5 meter range, so a smaller 30 cm tooth should not yield a larger size estimate. Nor can I figure out why the scientist quoted states it was 18 meters long and still growing, unless he's accounting for the fact that larger Livytan teeth have been found. But in that case he should have clearly stated he believes this to be a Livyatan tooth and said that this animal was likely a bit smaller than the published range of the holotype. If he wants, he could then surmise that the species might reach up to 18 meters. It always annoys me when scientists themselves make exaggerated or sensationalized claims to make their discovery more impressive. To me, the size isn't the most impressive part, although it does suggest a quite large Livyatan. The most exciting thing is that it shows Livyatan likely lived longer than what was previously predicted (and may have become extinct from the same factors that doomed Megalodon) and that it suggest that the species may have covered a far greater territory than previously thought. I would be inclined to put these articles in the Livyatan profile thread, but perhaps that is a bit premature. The tooth is 30cm but somewhat incomplete, so it is possible it was closer to the biggest teeth in the Peruvian whale. I think the immature statement possibly comes from the growth curve in the tooth if viewable. And there is always the possibility the tooth isn't the largest of the dentition. I've briefly discussed with the paleontologist, he says the size analogy is (obviously) based on Livyatan estimated size, noting it could be immature, so it was scaled to 15m. My understanding is that 18m would represent the adult size. The tooth will be studied anyway. I think they tend more to think it is a closely related species to Livyatan. Yes, I saw they said the tip and base are missing some parts. The tip looks like its only missing the smallest fraction, not sure about the base. Doubt it would add 6 or cms in length. And as you said, it's not known where to place this tooth in the jaw, so it may not have been the largest for the whale. We'd have to compare this tooth to the holotype's dentition to see if it could be determined where to place it. Not sure about the "growth curve" comment, is there some measureable technique that the paleontologist is relying upon? So the paleontologist thinks the animal likely represents a 15 meter specimen? The way the articles reported it, it made it sound like he was claiming it was up to 18 meters. Of course, the articles could be misquoting him, journalists do that all the time. There's obviously a large time gap from the 13 million year old Livytan holotype and this 5 million year old tooth. Morphologically, they look extremely similar, at first glance. Hard to know if they are the exact same species or not. |
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Post by theropod on Apr 22, 2016 22:57:46 GMT 5
elosha11 There are some data on that interaction that are relevant. Namely the bite damage was definitely not immediately responsible for the whale’s death, since the bone remodeling suggests it lived for 2-6 weeks afterwards (Kallal et al. 2009). So whatever it died from (killed by another predator? Infection? Sickness? Stranding? All are possibilities, although I think the systemic infection Kallal et al. proposed as an explanation makes sense.), it wasn’t a result of whatever damage the bite may have done. As for how significant that damage was, how do you know that with such certainty? Perhaps it took a bite causing its teeth to impact the rib (note that there doesn’t appear to be much of a ghash or anything we’d expect if it had sliced a large piece of meat out of its prey, the three lesions are all distinct from one another), realized its mistake and then broke off the attack. Perhaps it did very impressive damage to the cetacean, but it definitely wasn’t fatal and we have no other way of observing it, so where’s the argument from that? Aren’t you forgetting about the histology of the tooth? Obviously the annular growth layers in a sperm whale tooth’s dentine can be used to estimate its age and be matched to a growth profile to assess its growth status. This can be, and if frequently done with limb bones, so it should be possible with teeth that show Lines of arrested growth. Now, obviously they would have had to use a ct-scanner to do it, but is the fossil was indeed recovered in february it’s certainly possible that they did. Or maybe there are other, more superficial histological characteristics of sperm whale teeth that are related to their maturity. Or they made the kind of guess you accuse them of, but I don’t think the former should necessarily be our default assumption, let alone the only option. 18m appears very optimistic, but that generally goes for size estimates that are guesses for hypothetical fully grown life stages of an immature fossil (I’m sure I’ve discussed some examples of that in the past). A conservative estimate based on its preserved length would put the owner at ~83% the size of the Livyatan holotype, but there really isn’t that much point in giving anything but minimum estimates based on isolated teeth. Still, that’s a lot bigger than any other stem-physeteroid, and I agree that the most interesting thing is that it massively extends the range of giant raptorial physeteroids, both geographical and stratigraphical.
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Post by Grey on Apr 22, 2016 23:46:32 GMT 5
The original size of the tooth would be needed, its more likely position in the dentition (the fact the Livyatan holotype upper teeth aren't preserved may be problematic). I guess too they were able to count the annual layers in the tooth as some part of the root is missing. I don't think it is based on guess. Lambert once said me it would be possible to know Livyatan's precise age only while counting the annual layers of its teeth so I assume they had the opportunity to count them in the Beaumaris tooth.
The 18m size is based on the upper size estimate for Livyatan, the question is if Fitzgeral sees it as the potential maximum size in those killer sperm whales and that it was more like 15m or so or if it is indeed possible the specimen was in the neighborhood of 18m and not fully grown?
The occurence in the Pliocene was quite unexpected. It is quite astonishing to realize the oceans were frequented by various clades of really gigantic macropredators only a few million years ago.
I really think the BBC "seven deadliest seas ever" would need an update, the Neogene oceans were indeed inhabited by the most powerful aquatic superpredators in the history. I more and more doubt any Mesozoic marine reptile approached the league of the killer sperm whales and megatoothed sharks. Fascinating era.
Btw, I have the PDF of a very new book about the cetacean evolution. Those interested can contact me through email.
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Post by elosha11 on Apr 23, 2016 0:25:44 GMT 5
elosha11 There are some data on that interaction that are relevant. Namely the bite damage was definitely not immediately responsible for the whale’s death, since the bone remodeling suggests it lived for 2-6 weeks afterwards (Kallal et al. 2009). So whatever it died from (killed by another predator? Infection? Sickness? Stranding? All are possibilities, although I think the systemic infection Kallal et al. proposed as an explanation makes sense.), it wasn’t a result of whatever damage the bite may have done. I'm not sure why you are addressing this to me, I made similar points in my earlier response to Life. There are certain limited conclusions we can draw from the interaction, the rest is simply speculation.As for how significant that damage was, how do you know that with such certainty? Perhaps it took a bite causing its teeth to impact the rib (note that there doesn’t appear to be much of a ghash or anything we’d expect if it had sliced a large piece of meat out of its prey, the three lesions are all distinct from one another), realized its mistake and then broke off the attack. Perhaps it did very impressive damage to the cetacean, but it definitely wasn’t fatal and we have no other way of observing it, so where’s the argument from that? Again, re-read my post, I absolutely was not arguing the bite was fatal, to the contrary I said the exact opposite. As to how significant the bite was, all we know is that a comparatively small shark, plausibly a juvenile Meg, took a bite out of a living and much larger rorqual which (likely) sheared through blubber and muscle down the ribs, and left sizeable marks on the ribs. Of course there's always the possibility that the ribs were previously exposed from some other cause before the Meg bite, but it's more likely the Meg bit into an undamaged portion of a living whale. We will never know for sure, but assuming it was an undamaged portion of the whale prior to the bite, I find the bite to be quite an impressive demonstration of its weaponry, whatever the intent of the shark in doing so.Aren’t you forgetting about the histology of the tooth? Obviously the annular growth layers in a sperm whale tooth’s dentine can be used to estimate its age and be matched to a growth profile to assess its growth status. This can be, and if frequently done with limb bones, so it should be possible with teeth that show Lines of arrested growth. Now, obviously they would have had to use a ct-scanner to do it, but is the fossil was indeed recovered in february it’s certainly possible that they did. Or maybe there are other, more superficial histological characteristics of sperm whale teeth that are related to their maturity. Or they made the kind of guess you accuse them of, but I don’t think the former should necessarily be our default assumption, let alone the only option. I would think they would mention CT scans of the tooth if they had conducted them. That's not the type of thing you fail to mention when describing this to reporters. But sure, maybe that took place and maybe it didn't. I didn't know about the growth rings being countable in whales, and perhaps that took place. And if growth rings can be counted, I wish that would be done on the Livyatan holotype's teeth. It would give us a better idea of how old the animal was, which in turn could help answer the question whether it was large or average specimen.18m appears very optimistic, but that generally goes for size estimates that are guesses for hypothetical fully grown life stages of an immature fossil (I’m sure I’ve discussed some examples of that in the past). A conservative estimate based on its preserved length would put the owner at ~83% the size of the Livyatan holotype, but there really isn’t that much point in giving anything but minimum estimates based on isolated teeth. Still, that’s a lot bigger than any other stem-physeteroid, and I agree that the most interesting thing is that it massively extends the range of giant raptorial physeteroids, both geographical and stratigraphical. Yes, that's the most amazing part of this discovery. I tend to think this is a continuation of the Livyatan line, and hopefully further study of the tooth may inform us further on that point. My responses in bold above. |
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Post by elosha11 on Apr 23, 2016 0:30:39 GMT 5
The original size of the tooth would be needed, its more likely position in the dentition (the fact the Livyatan holotype upper teeth aren't preserved may be problematic). I guess too they were able to count the annual layers in the tooth as some part of the root is missing. I don't think it is based on guess. Lambert once said me it would be possible to know Livyatan's precise age only while counting the annual layers of its teeth so I assume they had the opportunity to count them in the Beaumaris tooth. The 18m size is based on the upper size estimate for Livyatan, the question is if Fitzgeral sees it as the potential maximum size in those killer sperm whales and that it was more like 15m or so or if it is indeed possible the specimen was in the neighborhood of 18m and not fully grown? The occurence in the Pliocene was quite unexpected. It is quite astonishing to realize the oceans were frequented by various clades of really gigantic macropredators only a few million years ago. I really think the BBC "seven deadliest seas ever" would need an update, the Neogene oceans were indeed inhabited by the most powerful aquatic superpredators in the history. I more and more doubt any Mesozoic marine reptile approached the league of the killer sperm whales and megatoothed sharks. Fascinating era. Btw, I have the PDF of a very new book about the cetacean evolution. Those interested can contact me through email. I don't see any reason to find this to be an 18 meter and still growing animal, given that the maximum size of the holotype is estimated to be less than 18 meters. But we all agree that we would have to know where to place this in the jaw, to truly know the size of the animal. Did Fitzgerald tell you that he thought the animal was around 15 meters but could grow potentially up to 18 meters? That's what I thought you were saying in your earlier comments. |
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Post by Grey on Apr 23, 2016 0:35:07 GMT 5
Lambert said me the Livyatan holotype was an adult but I don't know on which criterion.
The sensationalistic part about the Beaumaris whale is the potential of an immature animal already Livyatan/Physeter-sized.
Or maybe it was a bit smaller than Livyatan and would not have grown larger with time.
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Post by elosha11 on Apr 23, 2016 0:50:05 GMT 5
So far there really doesn't seem to be any reasoned basis for claiming this tooth represents an 18 meter and still growing animal. But now I'm not even sure if that's what he meant. Did he tell you in your communications that he thought the animal was around 15 meters when it died?
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Post by Grey on Apr 23, 2016 0:54:09 GMT 5
That's what I've understood but the discussion was brief, perhaps I've confused it.
For sure the resulting study will be way more solid.
The way I question this : was this animal really Livyatan-sized and immature?
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Post by elosha11 on Apr 23, 2016 0:56:03 GMT 5
Ok. I really question how anyone could make a determinative size estimate based on one tooth.
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Post by Grey on Apr 23, 2016 0:58:53 GMT 5
Simply because it is in the Livyatan tooth size range. But who knows, maybe it could be from a smaller big-toothed sperm whale? Albicetus was much smaller than Livyatan but had very large teeth for its size.
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Post by theropod on Apr 23, 2016 2:56:36 GMT 5
elosha11 Because it seemed as if you were considering this evidence for the prey a megalodon could take, or that there was some possibility that the whale was killed by the same shark that bit it in a predatory interaction (plausibly acting in conjunction with other sharks), which it definitely wasn’t. I also have read repeated mentions of "days later" in this thread, and I wanted to clarify that one of the few reliable things we can say is that the state of bone remodeling suggests at least two weeks (and less than 6). So what we know with some reliability is indeed that the whale was indeed neither killed by that shark’s attack, nor by the action of any other sharks that attacked at the same time, nor was it dying at the time. Animals don’t survive for several weeks when they have sustained lethal mechanical damage from a predator.
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Post by elosha11 on Apr 23, 2016 3:56:13 GMT 5
elosha11 Because it seemed as if you were considering this evidence for the prey a megalodon could take, or that there was some possibility that the whale was killed by the same shark that bit it in a predatory interaction (plausibly acting in conjunction with other sharks), which it definitely wasn’t. I also have read repeated mentions of "days later" in this thread, and I wanted to clarify that one of the few reliable things we can say is that the state of bone remodeling suggests at least two weeks (and less than 6). So what we know with some reliability is indeed that the whale was indeed neither killed by that shark’s attack, nor by the action of any other sharks that attacked at the same time, nor was it dying at the time. Animals don’t survive for several weeks when they have sustained lethal mechanical damage from a predator. No that's not what I was suggesting. Sorry if that's what you thought. My comment to Life was this: "I agree that this was likely a juvenile Megalodon and that it was an impressive bite. But we have to be careful about drawing too firm of conclusions because we do not know and will never know, the exact circumstances of the attack. The whale could have been sick and dying already, and the Meg could have been part of a larger group of sharks/other predators attacking it. We see that today with tiger shark groups attacking sick baleen whales. The rorqual could have died from its sicknesses, from this bite, or from multiple bites from multiple predators. Or it could have died from something else all together. All we have is a fraction of a rib to go on...
Or the whale may have been perfectly healthy and the Meg's bite led to its eventual death days/weeks later. Or it could have died from completely unrelated causes. All we know is that likely a juvenile Meg took a bite out of sizeable rorqual whale which did significant damage. It suggest a very powerful and lethal bite to so damage even a large whale, but that's really all we reasonably infer."Read more: theworldofanimals.proboards.com/thread/1325/extinction-megalodon#ixzz46b97CYsII stated the whale died "days/weeks" later because I recalled it being some matter of weeks, but didn't have time to look up the exact estimate. It is possible that the bite led to infection and directly caused the whale's death, or it was caused by something else. Quite possibly it died due to multiple factors, including this bite. And I don't think the fact that it died two to six weeks later prevents it from being an sick or old whale that was opportunistically attacked/bitten by more than one shark, including the one in question. Maybe it was able to escape them but later died of multiple wounds and/or sickness/age. Or maybe it was repeatedly attacked over a number of weeks or months. We will never know, but all of us should agree that there were a wide range of possible scenarios that could occur. But I never said or suggested that this Megalodon could directly kill the whale outright with a single attack. Wasn't this rorqual estimated at something like 12 to 15 meters? All I am stating is that it was an impressive bite from a much smaller shark upon a much larger cetacean. |
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Post by theropod on Apr 23, 2016 22:36:48 GMT 5
It wasn’t, there are no size estimates. For what it’s worth, 12-15m is likely to fall within the range implied by its most probable identity being Megaptera novaeangliae. But it’s really a guessing game, unless the taxonomic assignment is solid and the anatomical position of the element is too, there won’t be a solid size estimate.
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Post by Grey on Apr 23, 2016 22:42:25 GMT 5
S. Godfrey said me it is humpback/fin whake sized.
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