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Post by creature386 on Mar 2, 2014 22:30:42 GMT 5
Yes, so ? (I don't like spamming so I fill the post with useless things like this line^^). I have now looked it up and it looks like it yields 18.4 cm in slant height. 19.3/18.4*17?17.8 m. Not as much as 18 cm would have yielded, but still close to 18 m.
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Post by Grey on Mar 2, 2014 23:00:21 GMT 5
I have nothing against this. What about other reasons to favor mako there then... Or again, a higher percentage to the white shark, despite what says Kent. I don't know why he'd use something else than a method knew since 2009 (anterior to his talks). Or with the great he used a higher percentage, or got something close to 11 m mark. Still he points on 11 m, not something lower than this. I really don't think he used the same percentage than in Cardabiodon. Or perhaps in Cardabiodon this wasn't 4.2 % added, inducing your calculation is wrong somewhere. How do we get with 15 % for the white shark ? If this is approaching 11 m that can fit his quote. Based on white sharks. If you get 11.2 m with the shark lower that may fit. Only I'm not confident with that 15 % figure. I'd like something as explanation (from him). Thanks I had forgotten that, need to check it again. Why Kent did use the lower for Parotodus ? I'm not convinced that, by the greatest fate, the only GW set we have is such over the top with the formula. That's not like if it was at 15 %, we need to add 25 % to get something fiting its original size. Mollet did not specify something special about the proportions of that specimen on his page. We need another to verify this. Or another source of percentage. Despite I appreciate discussing with you we have a history of conflictual debates so it is not surprising that I get suspicious when you retain so much attention to something poorly interesting in terms of size estimate such as Megs centra. I participate because I'm in the search of the truth regarding this beast, or something approaching the truth, and as intelligent you are I cannot let you consider something as fallacious as this centra thing. That's not the same with our present discussion which is a field we investigate together. There was almost nothing to investigate in centra regarding the subject of this thread. And since carnivora, there has been so much discussion, fanboys and evolutions, I've not all the time been sure of your objectivity regarding Meg. But I'll do some efforts, I already did. Once asked Brett which tooth was it, but he did not respond. When discussing pliosaurs size, do I see posters reporting smaller, less spectacular specimens ? No. Like Meg, there is a tendency to investigate potential large sizes in all these giants predators. No if you want post pictures and measurements of smaller teeth no problem. At least this thread showed that monsters sizes above 15 m are not rare, I should count all the potential large specimens on that thread. The poster itself was from Balk, not Pimiento. And yes she said me after feedback from colleagues it was filled with errors. And probably outdated in terms of samples data. This is my point, this is the normal upper range of Meg. That was from the article not so long ago about her presentation. www.livescience.com/40920-megalodon-got-too-big-extinction.htmlThe posters are not definitive. How's that at anytime the largest exceeded 18 m ? In the poster this was not the case, and in the article (and the abstracts) it is implied 18 m is the max size of the species. yes I think Shimada is conservative as I don't think we'll have sizes estimates clearly exceeding 18 m, approaching 19 m. Shimada is perhaps not conservative on individual basis using posterior teeth of difficult assignement, but overall it is more conservative among the various methods. However I'm surprised that Gottfried appears finally to be the most conservative of all. Any estimate is of course approximate. That's far easier from our means behind our screen that attemptiong to rigorously get an average size, at any time from any region, for Megalodon. In others animals at least we can have skeletons when they achieved their lives, so the largest size they achieved at one given moment. In Meg we mostly have teeth shed at one time while the shark was still growing. Here's something to think about. Except for the teeth that are only shed by a still living, growing Meg, we have : The Belgium associated column, that may have possibly belonged to a shark at 9-10 m (rough figure). So a Meg died at this size. Killed by a predator(s), a large prey, disease, environemental cause or natural death ? The Uyeno et al. set. I've not seen any measurements but he did not look that large if I'm right. Then, same question, natural death or not ? The Hubbell's set, a shark that was around let's say 10-11 m. Died at this time. How. The Yorktown set which belongs to a larger Meg but probably still far of the monsters we have discussed. How it died ? The Denmark specimen. As the centra are too few and not assigable to predict size, using the tooth measurements let's say it was around 14-15 m. Same question here. Now the mysterious Peruvian specimen, this one reported very large. Certainly died of natural causes (or disease ?). So regarding the others, even if not all were predated (after all, even in the Miocene seas, it needs balls to take on a 10 m macrophagous shark) are they died of natural cause ? In that case, if they achived their life at 10 m of natural cause (then preserved), what can explain than a number of Megs has reached MUCH larger dimensions reaching or exceeding 17 m ? Subspecies, sizes differences depending the region, environemental causes, different longevity depending the time or the region...? Or smply in all cases predation (larger Megs, packs odontocetes...) ? Except for the Peruvian one (and let's exclude the Denmark individual) there's a clear disparity between these several animals died at a size of about 10 m when we know that this species could possibly approach a length twice that large. That is an interesting question to me.
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Post by Grey on Mar 2, 2014 23:01:31 GMT 5
Yes, so ? (I don't like spamming so I fill the post with useless things like this line^^). I have now looked it up and it looks like it yields 18.4 cm in slant height. 19.3/18.4*17?17.8 m. Not as much as 18 cm would have yielded, but still close to 18 m. Which tooth actually ? 17.8 m using Gottfried regression ?
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Post by creature386 on Mar 2, 2014 23:38:06 GMT 5
The largest known tooth. No, I have used no regression, just linear scaling, would the regression change a lot?
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Post by Grey on Mar 2, 2014 23:46:14 GMT 5
The largest known tooth. No, I have used no regression, just linear scaling, would the regression change a lot? I've not well understood, what the vertical height for that tooth you have predicted ?
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Post by creature386 on Mar 2, 2014 23:53:34 GMT 5
You said the 19.3 cm tooth was measured in slant height: theworldofanimals.proboards.com/post/11611/threadI have used this tooth for showing that you can get something close to 18 m when not using the tooth from Gottfried's paper, but the largest known today. For comparing both and being able to scale, I took the slant height of the largest tooth mentioned in Gottfried's paper which is (according to theropod) 18.4 cm: theworldofanimals.proboards.com/post/4623/threadI don't know the vertical height of the 19.3 cm tooth, in fact, I don't know a lot about it, I only know it was mentioned quite often here (I so badly lost the overview here).
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Post by Grey on Mar 3, 2014 0:08:22 GMT 5
I'm anything but sure that the tooth used by Gottfried was 18.4 cm in slant.
Anyway, we talked about Gottfried's regression which is unlikely to give sizes of 18 m. Now, this is method considered as conservative, perhaps the reason, added to direct sizing, why Gottfried thought 18 m within the range of Meg.
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Post by creature386 on Mar 3, 2014 0:51:32 GMT 5
May I ask for the reason of your skeptical view of the 18.4 cm figure?
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Post by theropod on Mar 3, 2014 1:14:18 GMT 5
I see no reason to presume that. Because that method does not include all the taxa he listed. At least for some, he must have used something different. Either way, at least the upper end of his figures is very clearly inconsistent with the use of a white shark. You are free to check for errors in my calculation. slightly below 11m for the upper jaw, slightly above for the lower. Its close to the lower bound. For everything else, he must have used a different method/shark species. As long as we are agreed that the great white shark is likely the best model for its jaw apparatus, this argument is unnecessary. I’m not confident with that either, but I’m even less confident in anything bigger than that. No, it’s not to have found such an outlier in a random individual, but the facts point out to it being the case here. 25% is definitely not a normal amount of spacing for a white shark. Or, perhaps the the 18ft 1/2in (=549.9cm) were still an overestimate, like the other lenght measurements. The point is, this specimen itself is problematic, certainly not fit to disprove a method and invalidate quotes from scientists. You know there are always two people needed for a conflictual debate? I’m sick of always being the one who’s accused of inobjectivity. Try to consider that please. those discussions are specifically about the biggest pliosaurian taxa and specimens. And I’d have no problem if you’d report smaller, less spectacular specimens of those. But C. megalodon is not of the same taxonomic diversity as the whole pliosaur clade. They are coauthors on that research. It doesn’t make a difference who of them made it. That must be a massive amount of outdated data indeed. What do you call a "normal upper range"? Crocodiles can exceed 6m, as can Great White Sharks. Allosaurus could reach 11m+. Elephants can reach 4m in shoulder height, and sperm whales can reach 18m+. But all of those are not normal for those species, not in a random specimen, not in an adult and also not in a specimen when it dies. If I got you right, we are fully agreed about this matter. That article is only a few days younger than the poster. And it’s even less definitive. Newspaper articles commonly misinterpret and misrepresent data. It is very strange to envision in just a few days they could have come up with various individuals equaling the largest from 12ma, and that size being even more common in periods were previously the biggest reported specimens were just 11-14m long. That means litterally a complete overhaul of the whole work, days after it has been presented. Is this not by any means a little "suspicious"? The weight estimate at 12ma indicates an animal in excess of 18m long following Gottfried’s method for estimating the weight. You think? Is there any scientific basis for that? Gottfried et al. was conservative from the beginning. Not including the astronomic attempts using wrong size estimates resulting in a freakish great white of course, which was only subsequently used by one single paper, and without really discussing the size estimate. The regression used gave conservative results, and I already discussed why, for the same reason for which Shimada gave conservative results using the same tooth. That’s not the case with the vast majority of fossil taxa, take dinosaurs as an example?. Of course if you count immature specimens. We already agreed on that when we were discussing the figure you reported from Facebook. Exactly. That affects all fossil organisms, few of them die because of old age. Most specimens on the fossil record, and most specimens in life, never reach the maximum size known for the species. And even between fully grown specimens, there are usually 2-3 fold differences. While I don’t think that’s the case here, individual variation would be your answer. ... Livyatan... Mortality rate in young specimens is certainly higher than in old ones. Hence, (old) particularly large ones are rare to find, in every species.
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Post by theropod on Mar 3, 2014 1:24:42 GMT 5
You said the 19.3 cm tooth was measured in slant height: theworldofanimals.proboards.com/post/11611/threadI have used this tooth for showing that you can get something close to 18 m when not using the tooth from Gottfried's paper, but the largest known today. For comparing both and being able to scale, I took the slant height of the largest tooth mentioned in Gottfried's paper which is (according to theropod) 18.4 cm: theworldofanimals.proboards.com/post/4623/threadI don't know the vertical height of the 19.3 cm tooth, in fact, I don't know a lot about it, I only know it was mentioned quite often here (I so badly lost the overview here). Hmm. Regarding Betucci’s tooth, it seems a near-myth, only known from a short mention in the Wikipedia article. But if you base it on Hubell’s, which is 18.4cm in slant lenght, you get almost 18cm in perpendicular height. Of course that’s problematic itself. I highly doubt that tooth was as wide and massive as Hubbel’s, more likely it was a more slender piece, perhaps taller, but not from a jaw bigger than the one Hubbell’s tooth belonged to. That also applies to whatever other tooth the 18cm tall one may have been. It’s most likely from a slightly different position also. Using 18m in perpendicular height with Gottfried’s regression, you get only 17m. I think you misunderstood me. Gottfried’s paper mentions no 18.4cm tooth (that’s the slant measurement of Hubbel’s specimen and 1 or two others we know of). It mentions the 168mm tall one was the biggest they had available. This measurement being not much smaller than the one commonly labeled as the largest, but sadly in a private collection (only reported on by book authors of questionable credibility AAARGH) makes sense, since it doesn’t seem to be THAT difficult to find a tooth that large or bigger.
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Post by creature386 on Mar 3, 2014 1:47:23 GMT 5
Thanks for the correction, I thought 18.4 cm would just be the slant height measurement for the 16.8 cm tooth. As for Betucci's tooth, I remember someone on carnivora has shown a more detailed length number of the tooth than the one on wikipedia, so it looks like they are other sources for it: carnivoraforum.com/single/?p=8240143&t=9380168
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Post by coherentsheaf on Mar 3, 2014 2:57:14 GMT 5
Thanks for the correction, I thought 18.4 cm would just be the slant height measurement for the 16.8 cm tooth. As for Betucci's tooth, I remember someone on carnivora has shown a more detailed length number of the tooth than the one on wikipedia, so it looks like they are other sources for it: carnivoraforum.com/single/?p=8240143&t=9380168rry I missread Gottfried to refer to slant height. 19.3cm is not form a published surce and refers to slant height.
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Post by Grey on Mar 3, 2014 13:27:21 GMT 5
The fact is he gave that range of size with the basis of several sharks including the white shark, that deserves to be further investigated. I'm no satisfied with the arbitrary 0-15 %. Just like Kent's Parotodus estimate, which exact percentage he used ?
There are three methods I know of so far actually :
- Lowry et al.
- The jaw length (= distance from symphysis to the corner of jaw, or 1/2 the jaw perimeter) is generally assumed to represent 10% of the total body length; the jaw length is measured in meters and multiplied by 10.
- Use the jaw perimeter in the regression equation of Mollett, et al, (1996) on extant Carcharodon to predict the body length.
That's best available we have so far. So either Siversson indeed used Lowry, most likely IMO as he indicated me to check his new paper, or he used one of the others, preferably the second because I don't know he could measure the symphysis to the corner in Hubbell's specimen.
What about unpublished data about Lamna nasus that he may own. Or that he assimiled nasus to paucus in his talk. I see no reason to think he did not use Lowry formula from Megalodon just because of that. We're not sure yet if the upper figure is that inconsistent with the white shark. Perhaps the possible range is even greater than what Kent suggests. The boneclones jaws at least suggests this.
I'm anything but skilled at maths, but I wonder about the validity of that 4.2 %.
And/or a different percentage.
A greater range of %...
Let's put it straight, until I found how he did his calculation about Hubbell's set, I'm more confident and interested in his estimate than in your based on a method that we still lack data regarding that particular case and use an arbitrary percentage within a wide range, possibly even wider than 15 % based on at least one white shark set. Not dismissing your work but there's no conclusion to be done at now. At least in my opinion. I will investigate this further asking Dr. Siversson. If you're not interested in this results and prefer your own, I will not share it one the board, except privately for those interested.
Just not convinced. Why the hell the only set we have as model is so much over the range we use here ? I'm in the opinion that the range is possibly greater.
I see no reason to think it is still an overestimate, it was revised several times and Mollet is very prone to caution with measurements. This shark was almost exactly the same length than the Cardabiodon in Siversson paper. That does not disprove anything, that just indicates there is a problem with the method, probably in the percentage we use. As for quotes from scientists, I justly base this investigation from Siversson quotes.
Okay. But another thing, you have to understand that you may seem like the guy who has response to everything without expressing cautiousness. Like here, you express your results regarding Hubbell's Meg size like if anything else, counting Siversson's estimate, was hogwash and don't considering you don't know all the data yet. More than I, you want to have the last word. Such a discussion could have been finished on a point of agreement like "the results are quite good but we investigate further to be sure".
The taxonomic diversity has nothing to do with this. The threads were named "pliosaurs size" "megalodon size" respectively. In both the largest specimens in each species/clade, that's the large potential sizes that were investigated. Anyway, in pliosaurs species or Meg we're unlikely to have by ourseleves a solid data about average sizes. Actually all the statements of average size in extinct animals here and on carnivora was educated simplified guess. For discuss this, I propose to wait Balk and Pimiento publication.
There, it was Balk's document and talk. They're coauthors but she was behind this poster and she presented the talk.
We've got an agreement, except that I don't consider these sizes exceptionnal in all these species. Allosaurus depends on the species itself, and in the case of sperm whales, sizes above 18 m are in that case (at least today) indeed exceptionnal (Ellis doubts many got over 18 m even in older times). Overall we have an agreement. But I do a difference between upper sized specimens and anormal individuals. Listed at 13 m or 18 m, both are a normal size attributed for the species. There's no need to recall each time "no, Megs were not all that large !". We can recall this for any species, not only Megalodon.
Pimiento posted the article herself on her twitter. The article is reliable.
Who said that Balk's poster was so close in time than this article ? The dates in Balk CV are only listed in the year. We don't know when that graph of Balk was made and when it was itself presented.
I know but you said "at anytime the largest exceeded 18 m ". Typo ?
Absolutely. I can be wrong though.
A basic observation, for now no estimate exceeds 18 m with Shimada. By tooth width related methods, we get sizes above 19 m. Pimiento said me too she had for now no individual above 18 m. Shimada also considered his own estimate as conservative. I don't say the results are themselves conservative on individual basis. Now we'll see in the final results if some 19-20 m Megs are figured after all...
Was agreed since a long time, Gottfried's estimates have all the time be stocky.
In dinosaurs we have an extensive history of growth rates, not in Megalodon.
Sharks grow their whole life, not only the immatures => the shark that shed Hubbell's big tooth was still growing at the time, at an ever slower rate, but still.
Which figure from FB ?
The point is, how died these individuals ? All predated ? Even in Miocene environnements, there are not many things able to take on a 9-10 m shark. If these individuals died of natural cause, this may suggest how Megalodon species (subspecies ?) knew huge variations of life history.
Would be only. I'm thinking even more that there were striking sizes differences between some Megs populations on a geographic basis.
Not counted it because all the Megs individuals I've listed come from areas where there is no sign of this odontocete's presence. No, I don't count in my questions the Peruvian specimen, which so far is certainly dead of natural causes....
It doesn't change that there is quite a size difference between these individuals which finished their lives at around 10-12 m (do you know Uyeno individual dimensions ?) and the much larger sharks that we have traces. They could have been predated but that could be also a sign of smaller populations.
I hope MacFadden will found something interesting about this.
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Post by Grey on Mar 3, 2014 15:40:32 GMT 5
You said the 19.3 cm tooth was measured in slant height: theworldofanimals.proboards.com/post/11611/threadI have used this tooth for showing that you can get something close to 18 m when not using the tooth from Gottfried's paper, but the largest known today. For comparing both and being able to scale, I took the slant height of the largest tooth mentioned in Gottfried's paper which is (according to theropod) 18.4 cm: theworldofanimals.proboards.com/post/4623/threadI don't know the vertical height of the 19.3 cm tooth, in fact, I don't know a lot about it, I only know it was mentioned quite often here (I so badly lost the overview here). Hmm. Regarding Betucci’s tooth, it seems a near-myth, only known from a short mention in the Wikipedia article. But if you base it on Hubell’s, which is 18.4cm in slant lenght, you get almost 18cm in perpendicular height. Of course that’s problematic itself. I highly doubt that tooth was as wide and massive as Hubbel’s, more likely it was a more slender piece, perhaps taller, but not from a jaw bigger than the one Hubbell’s tooth belonged to. That also applies to whatever other tooth the 18cm tall one may have been. It’s most likely from a slightly different position also. Using 18m in perpendicular height with Gottfried’s regression, you get only 17m. I think you misunderstood me. Gottfried’s paper mentions no 18.4cm tooth (that’s the slant measurement of Hubbel’s specimen and 1 or two others we know of). It mentions the 168mm tall one was the biggest they had available. This measurement being not much smaller than the one commonly labeled as the largest, but sadly in a private collection (only reported on by book authors of questionable credibility AAARGH) makes sense, since it doesn’t seem to be THAT difficult to find a tooth that large or bigger. Bertucci's tooth is not a near-myth, it's only poorly documented like most Megs teeth, Shimada saw it (with the others teeth of the reconstructed jaws) and find it impressive. The most complete mention is there. There are a total of 182 fossil teeth, all well preserved and most possess fine serrations and good enamel coverage. The natural colors of the fossil teeth vary, ranging from earthy browns to gunmetal blues to rusty orange. The largest tooth, measuring 7 5/8 inches in length along the diagonal with 7 ¼ inches of it fully exposed above the gum line, and is among the largest Megalodon tooth ever discovered. Three other anterior teeth measure over 7 inches in length but have ¼ inch of their length covered under the gum line. fineart.ha.com/s/d/shark-jaws.pdfI'm not sure if the tooth wasn't just as wide as Hubbell's, there's no direct picture of that one and no reported direct measurement of its width. It could be in the same region of width without being as wide, somewhere within the 13.5-15 cm range of width. Width is less often reported. It is also not impossible that these teeth came from the same shark. Both were found by Bertucci in the same area and both are gigantics. Or simply this area was home to regular largest members of the species. Bertucci found numerous huge teeth there enough to built a giant (though not scientifically accurate) jaw : Note these teeth are the lower anterior, not the larger upper where is certainly the specimen we're talkin about. But I wouldn't argue anything about this without more precise informations about that tooth. In any case I doubt too that tooth is about 19 cm in vertical height, which would allow to get 18 m from Gottfried's regression. At best, perhaps it would indicate an approaching 18 m TL without reaching it.
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Post by theropod on Mar 3, 2014 19:13:08 GMT 5
That’s a simplistic ratio, just like the "1cm of tooth lenght=1m of total lenght" or the "1cm of root width=4 ft of TL" I wouldn’t give much credibility to it. Thats the regression Kent used. That’s not difficult. According to Kent, the tooth-free gape adds 17%. I thought that he might have used something like the second, becasue I recall at one time he wrote something like that in a mail you posted. Lowry et al gave no figure for Lamna, which means he cannot have used their formula for this taxon. Period Apart from that, isn’t Lamna a fairly terrible model, considering it’s so much smaller than even Great whites and makos? Above 15% is simply not a feasible assumption for a white shark. Kent explained why (I’ve sent you the quotes), the purpose of cutting teeth constrains the spacing they can have. EDIT: here are the quotes in question, I’ve now asked his permission to post them: Darius; The spacing between teeth in lamnids is quite variable and can range from no space (i.e., the root lobes of adjacent teeth are on contact) to at least 25% of the root width. The spacings are the largest and most variable in Isurus and smallest and least variable in Carcharodon. The spacing in the Parotodus paper were consistent with Carcharodon, as well as those of Alopias, which have teeth morphologically similar to Parotodus. I suspect reconstructing Carcharocles size from bite size would be fraught with difficulties. One problem is that we don't know the dental arcade shape in Carcharocles: is it relatively long and narrow (e.g., Carcharodon, Isurus) or short and broad (e.g., Alopias). In the Parotodus paper I assumed arcade shape was comparable to that of Carcharodon, but since the phylogenetic position of the otodontids is not well defined, this is open to debate. I'm currently dealing with this problem in giant alopiids that have very large teeth that are convergent in morphology with Cosmopolitodus and Carcharodon. We have no extant lamniforms with broad dental arcades with this tooth morphology, and so it's difficult to reconstruct body size. The other problem is that bite size can change dramatically under different conditions. If the prey's body is bent when the bite is delivered any subsequent changes in prey body position after the bite will alter the apparent bite size and arcade shape. This would, in turn, produce a good deal of statistical noise in the data. Good luck on your project and let me know if I can be of any other help. Brett Darius; You've very precisely identified the fundamental problem -- the results you get depend on the extant species used as a model. And carcharias, paucus, and oxyrinchus giving very different results isn't surprising, since megalodon almost certainly exhibits decoupled scaling compared to these species. Intuitively we'd expect carcharias to be a better model because of the general similarity in tooth morphology, although the teeth are not identical and this is likely responsible in large part for the decoupling. I'd also be very reluctant to use a 25% tooth spacing in megalodon. In his 1988 article on shark tooth biomechanics, T. H. Frazzetta argues that cutting teeth with serrated edges need to be relatively close together near the tooth bases to facilitate the removal of prey tissues that would otherwise become wedged between the teeth. No such constraint is present on grasping teeth, and wide spacing actually allows the upper and lower teeth to intermesh, providing a more secure grip on small, active prey. I'd argue that carcharias would be the best model to use to estimate body length, even it is a fairly unreliable (as the length estimate for the 5.5.m individual indicates). Brett Why should you not share if if you get a response? that the range is possibly greater with some individuals we cannot exclude. But that doesn’t mean that those would be a good model. It would pretty much equal to Gottfried et al’s direct sizing approach, nitpicking the highest. That’s the point. there were several measurements in his list, that were all debunked. Lenght measurements of Great white sharks are commonly inaccurate. The measurement for this shark was almost the same as the estimate in Newbrey et al. Yes, there may be a problem in the percentage. But if you change the percentage, there will be a problem with those sharks that we know have a smaller spacing (or none at all). So what would you rather use, a spacing you extrapolated for what’s likely an outlier, or a spacing we know occurs in Great whites? we all know Most pliosaurs are far smaller than the biggest ones (e.g. Simolestes, Peloneustes, Liopleurodon...). Few people think about that in C. megalodon. Again, I”ve got no problem if you post estimates for smaller specimens of pliosaur. But it is a different thing to search for the largest species in a higher-rank clade, and to search for the maximum size attained by a species. We don’t know whether they are going to give an average size for adult specimens. Those average sizes are rough but comparable. Maximum sizes are not, because we have a very different figure in an animal known from 400 specimens, and an animal known from 3. Coauthors know what the other one is talking about, especially if the abstract they submitted has both their names on it. As mentioned above, it’s a big difference whether in 3 specimens you find such a size, or whether you find it in hundreds. It is a lot more exceptional if a size is sometimes reached in the latter. and we have got such massive sample biases with fossil animals (not that much with most extant species tough, excluding deep-sea animals). Whether you call it exceptional or not is a matter of terminology. You mean that? " Their poster tells us something very different, and not long ago you remarked to be surprised that at any time the largest exceeded 18m because you thought Shimada’s method was conservative." I was responding to you, because you wrote that at every time megalodon reached 18m, even though you claim that Shimada’s method never yielded such results and that you even doubted the largest one in the graph. Well, afaik there is simply no basis for saying that. There are differences, depending on what tooth you use. Because Shimada did not estimate the largest specimens, and because the subsequent studies using the method studied a nursery area. That in such an area specimens approaching 18m were found isn’t necessarily conservative. And in the poster, as previously remarked, the largest does exceed 18m. Exactly, so the method in general isn’t either. Some results are. You’d have no guarantee for that with other methods either. yes, that, again, applies to the majority of animals. The one you wrote Tom Holtz had reported. Yes, that falls under the term "individual variation". What do you count as "natural causes"? Just old age? Disease? Consequences of an encounter with a pod of nasty odontocetes? It most likely is, most species vary in size depending on the individual time period and geographic range, the sex etc. No, I don’t know the exact size of that specimen. The tables in Uyeno et al. confuse me. But the biggest measurement listed and the biggest in the row that seems to refer to tooth width are 136 and 106.4 respectively, so (assuming that’s in millimetres, a near-certainty) it’s save to say it’ not humungous, probably about comparable to the yorktown dentition or slightly larger.
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