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Post by Grey on Jun 23, 2013 21:27:21 GMT 5
Well, then you shouldn't just use the most liberal Carcharodons, should you? and you should also note the uncertainity in the root width scaling factor. btw, since the widths ought to be pretty constant among sharks, does someone have data on the width of extant lamniform teeth? would help to clear up the latter. These are not liberal Carcharodon, these are large Carcharodon used for large Carcharocles specimens based on the direct sizing by Gottfried et al. I've already noted the uncertainities in the width method as well, if only you could read carefully my posts. |
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Post by theropod on Jun 23, 2013 21:45:00 GMT 5
These are Carcharodon that produce very liberal estimates when compared to the average one. I don't see you noting any incertainities in any of the estimates but the (?) after the 7,2m-gws-based one.
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Post by Grey on Jun 23, 2013 21:52:02 GMT 5
These are Carcharodon very large so very large meg teeth are applied to them. The purpose is to estimate a maximum hypothetical based on individual maximum sized Carcharodon.
I've posted the video by Hubbell about the uncertainities of tooth width based of white shark (which though seems to work well with others lamniforms). In any of these extrapolations extrapolated far beyond the extant data of the analogous white shark, this produces great margin of errors. The results are alway just indicative and possible, never absolute facts.
I don't use Shimada and Randall as their methods are based on crown height measurements, datas which are often lacking in examples of large teeth.
Another difficulty with Shimada is that it is difficult to determine the exact position of the tooth in the jaws, position in the jaws being vital to get the most probable estimate...And once again, Shimada is based only on the great white. Just like for Gottfried and Randall, the proxy is perhaps not that good.
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Post by creature386 on Jun 23, 2013 21:56:36 GMT 5
These are Carcharodon that produce very liberal estimates when compared to the average one. I don't see you noting any incertainities in any of the estimates but the (?) after the 7,2m-gws-based one. You have to keep in mind that using another lamnid would too give higher results than based on the average Carcharodon, so I wouldn't call such estimates too liberal. |
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Post by theropod on Jun 23, 2013 21:57:53 GMT 5
So is it about establishing probable size estimates, or is it about hypothetical maximum sizes? Remember you often state I was speculating too much and making up overenthusiastic stuff...
You only use the two specimens that produce the most liberal estimates, while you ignore the 10 other large shark specimens in Gottfried et al. whose average suggests something completely different from the numbers. So is this about hypothetical maximum size or not? If not, you should at least also use the other sharks.
Read my post again please! This is about the uncertainity of the scaling factor (demonstrated by the table from the exhibit you repeatedly stated was excellent), not the method as a whole, which, as I stated for several times, is likely the best we have.
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Post by theropod on Jun 23, 2013 21:59:10 GMT 5
These are Carcharodon that produce very liberal estimates when compared to the average one. I don't see you noting any incertainities in any of the estimates but the (?) after the 7,2m-gws-based one. You have to keep in mind that using another lamnid would too give higher results than based on the average Carcharodon, so I wouldn't call such estimates too liberal. Based on direct sizing from great whites, which it is advocated as, it is definitely liberal, pehaps too, perhaps just liberal. Do you have data on other scaling analogoues? |
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Post by creature386 on Jun 23, 2013 22:04:05 GMT 5
Gottfried said that great white sharks have proportionally very large teeth for lamnid standards.
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Post by theropod on Jun 23, 2013 22:04:37 GMT 5
Very large overall or just very long?
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Post by Grey on Jun 23, 2013 22:04:48 GMT 5
So is it about establishing probable size estimates, or is it about hypothetical maximum sizes? Remember you often state I was speculating too much and making up overenthusiastic stuff... You only use the two specimens that produce the most liberal estimates, while you ignore the 10 other large shark specimens in Gottfried et al. whose average suggests something completely different from the numbers. So is this about hypothetical maximum size or not? If not, you should at least also use the other sharks. Read my post again please! This is about the uncertainity of the scaling factor (demonstrated by the table from the exhibit you repeatedly stated was excellent), not the method as a whole, which, as I stated for several times, is likely the best we have. I use the extrapolation by Gottfried (based on 73 individuals) as well as I use the direct sizing method (based on maximum sized white sharks). I don't speculate, I use actual published estimates, even if neither are good, even if I favor the most conservatives. I don't use the table, I use the 1,37 m per cm stated by Jeremiah in its interview. The method was in the educative book of the exhibit, I've not looked at it. But Jeremiah's method is 4,5 feet or 1,37 m per cm. |
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Post by theropod on Jun 23, 2013 22:07:05 GMT 5
Then how do you explain the table?
That's the point. An estimate doesn't get good just because its published, especially if the majority of other data from the same work suggest something completely different. It is speculative to assume C. megalodon had the proportions of such outliers.
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Post by creature386 on Jun 23, 2013 22:07:59 GMT 5
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Post by Grey on Jun 23, 2013 22:09:14 GMT 5
Then how do you explain the table? That's the point. An estimate doesn't get good just because its published, especially if the majority of other data from the same work suggest something completely different. It is speculative to assume C. megalodon had the proportions of such outliers. I use published datas that are not rejected even if discussed. That table was originally made for kids. Jeremiah's method is 1,37 m per cm. But yes, in all these methods, there are margin of errors because extrapolated far beyond the data range. Hence, the results are possible but not factual. |
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Post by theropod on Jun 23, 2013 22:21:39 GMT 5
I see... Any idea why their chondcranial reconstructions shows larger teeth in C. megalodon than in C. carcharias? |
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Post by Grey on Jun 23, 2013 22:23:30 GMT 5
I see... Any idea why their chondcranial reconstructions shows larger teeth in C. megalodon than in C. carcharias? The purpose of the comparison is to show that megalodon possessed more robust and heavier teeth at parity, but I've yet to see any data that megalodon's teeth were larger relative to the body size than in the white shark. |
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Post by creature386 on Jun 23, 2013 22:40:32 GMT 5
I see... Any idea why their chondcranial reconstructions shows larger teeth in C. megalodon than in C. carcharias? Well, he said that the teeth of Meg could have been a bit larger (he only said much larger is unlikely):  |
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