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Post by Grey on Jan 19, 2016 4:32:31 GMT 5
It would be needed to estimate TL of the 544 teeth using dentition width to see the differences. I suspect the differences are going to be decisive, even though I couldn't argue Pimiento's results are invalidated. I currently discuss with a PhD student working on this, he already suggests to takes Pimiento's data with a grain of salt at this point. Regarding the Chilean teeth, you can discuss with meg teeth collectors, they all agree that teeth from that region are noticeably larger than from anywhere else, and this despite the embargo. For example look at this one, I don't know the measurements but there little doubt it is larger than anything in Pimiento's sample. Sampling bias toward larger teeth can be expected from any region of the world, not only the Bahia Formation, it doesn't change that Chilean specimens are known to be noticeably big among collectors. It is very much suspected the largest in the world is Chilean.  |
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Post by Grey on Jan 29, 2016 13:19:09 GMT 5
On my instigation, a new work about meg TL based on dentition size is in preparation, conducted by two researchers from the Florida MNH. I've presented a preliminary work and they've expressed enthusiasm about it, considering it poster quality. I will avoid to discuss this too much on the forum from now.
I can say this disregards Lowry's 2009 method because of the unknown interdental spacing in meg and only measurable in fresh white shark jaws and the vast underestimates this method yields in dentitions from sharks with known TL (even adding arbitrarily 15% of tooth spacing as suggested earlier in this thread).
It also appears that TL estimates for meg based on upper anterior teeth scaled from the white shark (height or width) imply a shark with a dentition 25-35% larger (in summed width) relative to the white shark i.e. the 16m megatooth from Gottfried would have a total dentition size corresponding to a theoretical 20-21m white shark (although Gottfried et al. expected a "somewhat larger mouth than the white shark" they never actually measured the associated dentitions nor compared them with white sharks dentitions).
Nevertheless I expect improvements and tweaking by the two guys.
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Post by elosha11 on Jan 29, 2016 21:36:11 GMT 5
Nice job Grey! I always suspected that all the rare teeth you've hunted down might assist some researchers, if they'd just take the time.
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Post by Grey on Mar 18, 2016 1:32:52 GMT 5
  If, as the shape and thickness of the root and and the narrow base of the crown seem to suggest, this broken tooth was a Lower Anterior, it is likely the whole dentition at least (or the whole shark) may have been really outsized. By comparison the adult Yorktown dentition has its Lower Anterior in the 86-98 mm of crown width. |
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Post by Life on Apr 12, 2016 17:40:22 GMT 5
GreyThe images in your post are not working. I'd suggest that you use tinypic.com to upload pics; it's a good site for the said purpose.
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Post by theropod on Apr 13, 2016 15:30:22 GMT 5
@life Are you referring to his last post? I can see the images.
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Post by creature386 on Apr 13, 2016 22:25:53 GMT 5
Can you at least view them when you click on them (as a link is included)?
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Post by Grey on Apr 23, 2016 0:44:09 GMT 5
Life hmm the tooth is pretty viewable for me.  Is there someone who has access to pictures of white sharks dentitions with known total length, other than from the 1996 book or from the elasmo website?
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Post by elosha11 on Jul 6, 2016 22:25:01 GMT 5
Apparently there are extremely large teeth from Argentina, around Bajo del Gualicho, Rio Negro (Black River) Province. I am in touch with a reporter who is trying to uncover private collections rumored to have teeth exceeding 20 centimeters in slant height. But the local museum there also has some very large teeth. But before I post pics of the Museum's teeth, here's an absolutely enormous one from the same region of Argentina, posted from a private collector. He claims it dates back to the Oligocene. It's just about 7 inches in width and I think probably over 7 inches in slant height. Assuming the accuracy of the picture, Theropod/Blaze, either one of you want to try to scale the vertical and slant height properly based on the tape measure? EDIT - Actually, I've done a rough scaling myself. Assuming the measurement's accuracy, my scaling would indicate it's well over 7 inches in slant height and approaching or even exceeding 8 inches. I will try to contact the website owner for further verification. Carcharodon megalodon. Shark Teeth. Oligocene
Bajo del Gualicho, Rio Negro Province.
Unfortunately they are not so common here. It's a large specimen from Argentina.Description and picture from the website: www.mineralesyfosiles.com.ar/fossils.htm |
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Post by elosha11 on Jul 6, 2016 22:36:28 GMT 5
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Post by Grey on Jul 7, 2016 7:12:34 GMT 5
elosha11Great to hear from you, I'm of course curious about the investigations of your contact. However, the rule in the first picture is in metrics. It looks more like a 7cm wide tooth, I don't think Argentines use inches. I can't see the pictures in your second post. Anyway I've done a quick research about this Museum and found this; if what the ruler in this picture is accurate, this is amazing :  www.anbariloche.com.ar/noticias/12/06/2016/53494-el-tiburon-mas-grande-que-existio-el-megalodonThis reminds me of the French paleontologist who told me to have observed a 22cm tooth in a Museum in Angers, long ago... Before going enthusiastic, contacting the Museum is needed, I had contacted several Chilean and Peruvian Museums while investigating about Livyatan teeth. I've often been disappointed by the "fish stories" about giant Megs, pliosaurs or Livyatan teeth before. But 23cm for the ruler seems quite precise. I note their reproduction of the Meg jaws is massive and sounds quite rigorously built although the teeth are reproductions.  Some news, the study about Megalodon size based on dentition size is now involving Dr. M. Siversson as well. The team is progressing.
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Post by elosha11 on Jul 7, 2016 18:32:18 GMT 5
Grey, you appear to be right about the tape measure for my first tooth. That's disappointing. I am also aware of the 23 centimeter tooth you are showing. I'm in contact with the reporter who wrote the article showing the tooth and also with the Museum. So far, they have not confirmed this scale is accurate and in fact the reporter seems to express uncertainty as to whether the measurement is accurate. The picture of the tooth is also posted on another Museum website. plus.google.com/+MuseoAPB/postsSo we will see. It would be a real letdown if they inaccurately scaled it. |
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Post by elosha11 on Jul 7, 2016 18:39:38 GMT 5
I'm glad your study is proceeding. Siversson will be a great addition. Any idea how long the study will take to complete?
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Post by Grey on Jul 7, 2016 19:32:57 GMT 5
I've myself contacted him and the Museum, hopefully one of us will get a response.
The tooth would be actually around 21cm high if the ruler is accurate.
I don't know when the study will be finished and published but given my position I'll know the results before.
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Post by theropod on Jul 7, 2016 19:49:18 GMT 5
Apparently there are extremely large teeth from Argentina, around Bajo del Gualicho, Rio Negro (Black River) Province. I am in touch with a reporter who is trying to uncover private collections rumored to have teeth exceeding 20 centimeters in slant height. But the local museum there also has some very large teeth. But before I post pics of the Museum's teeth, here's an absolutely enormous one from the same region of Argentina, posted from a private collector. He claims it dates back to the Oligocene. It's just about 7 inches in width and I think probably over 7 inches in slant height. Assuming the accuracy of the picture, Theropod/Blaze, either one of you want to try to scale the vertical and slant height properly based on the tape measure? EDIT - Actually, I've done a rough scaling myself. Assuming the measurement's accuracy, my scaling would indicate it's well over 7 inches in slant height and approaching or even exceeding 8 inches. I will try to contact the website owner for further verification.Carcharodon megalodon. Shark Teeth. Oligocene
Bajo del Gualicho, Rio Negro Province.
Unfortunately they are not so common here. It's a large specimen from Argentina.Description and picture from the website: www.mineralesyfosiles.com.ar/fossils.htmMore like 7-8cm probably, who sais that measuring tape is in inches? It sais "3m" on there, not "10ft". Also check out some of the other fossils with the same tape, it would be extraprdinarily wide if it really was in inches, and some of the other fossils would be unusually large too. |
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