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Post by theropod on Jun 22, 2013 22:50:31 GMT 5
Seems rather 11,4 to me (648/67px) Grey: Just wondering, could you include a references-section (links) in the opening post please, since you are basing a whole thread full of size estimates on it? And I'd be interested in that supposed giant 7,2m Great white, were was it reported? The "direct sizing" seems to produce overestimates, at least based on this: books.google.at/books?id=2My8M5tL-KIC&pg=PA60&lpg=PA60&dq=great+white+tooth+length+total+length&source=bl&ots=3qkJ367cpS&sig=hRdXM1ExDKyaDKh9G0BTGAcCACk&hl=en&sa=X&ei=rODFUczRHY2Wswbl4oHIAg&redir_esc=y#v=onepage&q=great%20white%20tooth%20length%20total%20length&f=falseReporting 10 large female great whites to have an average tooth height (Upper anterior 2) of 5,92cm and an average TL of 5,5m. This has a 5 times larger sample and should be more realistic. Using the largest tooth this would yield a lenght close to 18m, and for the uften-used 16,8cm one it yields 15,6m. This is nowhere stated as an overestimate but the most simple non conservative method of sizing. The references are in the name of methods in the first post of the thread. Well, the two specimens you use produce overestimates compared to the sample from Gottfried. Why don't you describe the root width method in that post? If it is 1,37m, that means proportionally not just shorter but also less wide teeth than in C. carcharodon. A reference and basis for that method would be good, no? |
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Post by Grey on Jun 22, 2013 22:54:20 GMT 5
This is nowhere stated as an overestimate but the most simple non conservative method of sizing. The references are in the name of methods in the first post of the thread. Well, the two specimens you use produce overestimates compared to the sample from Gottfried. Why don't you describe the root width method in that post? If it is 1,37m, that means proportionally not just shorter but also less wide teeth than in C. carcharodon. A reference and basis for that method would be good, no? The direct sizing is also from Gottfried et al. works. It can also be used, the extrapolation based on the sample is certainly more conservative and more reliable. But the purpose of the direct sizing is to indicate a possible max using an UA. Gottfried did not spent time to write about a method he thinks useless either. But yes, this is not because I use it that I believe in it. Nor in the others, even if I have personnal preferences... I thought that everyone was aware of the methods (which are explained in the wiki page). |
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Post by theropod on Jun 22, 2013 22:57:56 GMT 5
Isn't the purpose of this thread also to explain the methods? I didn't see the emthod give anywhere.
even more interesting would be what it does base on, and how it was verified, instead of reading a long array of size estimates.
In any case, only using the liberal direct scaling, not the other specimens, gives a pretty one-sided image.
Also, I still don't get were the 1,37m are from. The tooth from that table seem to indicate a root width of 5,08cm for a 635cm long shark. Scaling that up to the largest known teeth (~15cm) yields 18,75m. That's why I'd like to have a bit more detailed explanations on the method at least.
It has been some time since I last used a wikipage for information...
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Post by Grey on Jun 22, 2013 22:58:50 GMT 5
I now get ~15,6 m. This is a really huge specimen. Using this methods, we get larger sizes approaching 20 m TL (Siversson), but more interestingly, we see numerous teeth indicating sharks in the 13-17 m range, more than using the others methods, in that meg teeth are more wide and compact than large. |
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Post by Grey on Jun 22, 2013 23:01:13 GMT 5
Isn't the purpose of this thread also to explain the methods? I didn't see the emthod give anywhere. even more interesting would be what it does base on, and how it was verified, instead of reading a long array of size estimates. It has been some time since I last used a wikipage for information... The wikipage about megalodon is excellent and wiki is actually a rather good and reliable source depending the article, much more than years earlier. The meg articles is certified as "Good Article" anyway... I will edit my first post and present the methods which I thought everyone had read about and knew. You've already found Gottfried's works. |
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Post by Grey on Jun 22, 2013 23:11:11 GMT 5
Theropod, where did you found that meg teeth are less wide than in Carcharodon ? Jeremiah established it based on Carcharodon actually, but it appears that this method works well with others predatory lamniforms and not only the white shark, unlike Gottfried and Shimada.
That's why Mike Siversson relies on it, despite it displays the same uncertainties than in Gottfried (and not Shimada which uses allometry instead), it is not restricted to Carcharodon which is not an obligate template. It works also with others perhaps phylogenetically more related species.
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Post by theropod on Jun 22, 2013 23:14:01 GMT 5
I think root width is a good method, due to the obvious relationship with jaw size, but if it is 1,37m for every centimetre of tooth, that means proportionally smaller teeth than in the table (1,25m/cm for the largest at least).
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Post by creature386 on Jun 22, 2013 23:15:53 GMT 5
The table I have shown was for megalodon.
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Post by theropod on Jun 22, 2013 23:16:41 GMT 5
Then its even stranger...
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Post by creature386 on Jun 22, 2013 23:17:22 GMT 5
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Post by Grey on Jun 22, 2013 23:21:37 GMT 5
I think root width is a good method, due to the obvious relationship with jaw size, but if it is 1,37m for every centimetre of tooth, that means proportionally smaller teeth than in the table (1,25m/cm for the largest at least). That's weird, it would make Jeremiah's conservative, which I don't think can be considered as such, despit giving less large results than the direct sizing. But since it works with others lamniforms as well, it is still interesting. However, I have faith in it but not that much. My personnal opinion about meg size is the one of Brett Kent, very cautious. I believe that a maximum size of 18 m TL is possible given the uncertainities of such methods, but I'm opened to sizes approaching 20 m TL proposed by Siversson given that the root width works well with others lamniforms than the white shark. And also given these hints of this large skeleton. For personnally speaking with Klaus Hönninger, I know he thinks that regarding that unique meg skeleton specimen, an appropriate method would be 2,7 m per inch of UA tooth in slant height, but he advised me to not consider this one as valid yet. |
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Post by Grey on Jun 22, 2013 23:25:02 GMT 5
Mark Renz book is globally reliable. Jeremiah's method was presented in it and several meg specialists (Kent, Hubbell, Ward, Jeremiah...)worked on it or were used as advisers. Some datas are obsolete (the last chapter was less serious as it made a count of the top 10 predators of all times, meg being second behind the 150 tons liopleurodon of the time...), but regarding the scientific and informative content, this is still a high quality source. |
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Post by creature386 on Jun 22, 2013 23:26:05 GMT 5
Yeah, the last chapter was the reason why I asked that question.
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Post by Grey on Jun 22, 2013 23:28:42 GMT 5
The tooth width method can be trustable, but not totally either, according to Dr Gordon Hubbell (perhaps the world meg expert as even paleontologists use him as reference, he has studied fossils sharks for 40 years).
Anyway, I don't know his personnal educated guess, but I know Gordon Hubbell states megalodon reached at least 60 feet regardless of the various methods.
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Post by theropod on Jun 22, 2013 23:32:16 GMT 5
I think root width is a good method, due to the obvious relationship with jaw size, but if it is 1,37m for every centimetre of tooth, that means proportionally smaller teeth than in the table (1,25m/cm for the largest at least). That's weird, it would make Jeremiah's conservative, which I don't think can be considered as such, despit giving less large results than the direct sizing. But since it works with others lamniforms as well, it is still interesting. However, I have faith in it but not that much. My personnal opinion about meg size is the one of Brett Kent, very cautious. I believe that a maximum size of 18 m TL is possible given the uncertainities of such methods, but I'm opened to sizes approaching 20 m TL proposed by Siversson given that the root width works well with others lamniforms than the white shark. And also given these hints of this large skeleton. For personnally speaking with Klaus Hönninger, I know he thinks that regarding that unique meg skeleton specimen, an appropriate method would be 2,7 m per inch of UA tooth in slant height, but he advised me to not consider this one as valid yet. I think a maximum (at least known to date) of ~19m as stated by Siversson is most likely, based on the root width table. But apparently, it is in disagreement with what you can read in "Hunting the Hunted". I just whished that book was a bit more in-detail and not just superficial. It contains really nice photographs of bite marks tough. We have to determine which is accurate, the 1,25m/cm or 1,37m/cm root width. for the largest known teeth, that makes a difference of almost two metres. |
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