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Post by theropod on Feb 27, 2014 16:58:03 GMT 5
12.66cm wide, 16.36cm in perpendicular height, 17.65cm on the longer and 16.92 on the shorter slant
It looks a lot like an upper anterior. Its crown is symmetrical, not inclined to one side, and has slightly convex edges, not slightly concave (at least on one side) as in most laterals. The roots are never perfectly symmetrical anyway.
It reminds me most of an A1
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Post by creature386 on Feb 27, 2014 17:32:10 GMT 5
Wow, and this time I have thought something like "this can't be an A1". Thanks for the crown/root correction.
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Post by theropod on Feb 27, 2014 22:32:57 GMT 5
That’s just what I think most likely, I could easily be wrong. There sadly is no rigorous published diagnosis for Identifying megalodon teeth.
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Post by Grey on Feb 27, 2014 22:43:23 GMT 5
Oh that's really probably a UA, and experienced sharks teeth hunters and sharks fossils specialists have no big trouble to identify teeth, that's the posteriors that are more difficult to assign because of ontogeny.
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Post by theropod on Feb 27, 2014 22:58:27 GMT 5
That’s also only an opinion. You cannot be sure unless you know a complete descriptive catalogue listing diagnostic morphometric characters and quantifying the range of variation.
Shark teeth hunters are not the most reliable source out there. Specialists certainly know what they are talking about, but as you see even they cannot identify teeth with absolute precision. The identification remains a problem.
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Post by Grey on Feb 27, 2014 23:31:24 GMT 5
Don't exagerate man ! For posteriors yes, but identifying an Upper Anterior is really not that difficult. In several docs with researchers finding Meg teeth, they often remark and argue directly what tooth is it. The latest tooth is most likely an UA. Experienced sharks teeth hunters like Jim Bourdon are absolutely reliable.
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Post by elosha11 on Feb 28, 2014 2:12:11 GMT 5
Don't know if this has ever been posted here, but it's found at Catalina Pimiento's flicker page, discussing Panama's fossil sharks. Shows a Megalodon vertebrate from Belgium presumably from the set of centra and associated teeth found there. The largest centra are said to be 23 cms in diameter. www.flickr.com/photos/sharkspanama/4109437905/in/photostream/Picture doesn't post, but can be viewed at link above.
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Post by coherentsheaf on Feb 28, 2014 2:56:50 GMT 5
Don't know if this has ever been posted here, but it's found at Catalina Pimiento's flicker page, discussing Panama's fossil sharks. Shows a Megalodon vertebrate from Belgium presumably from the set of centra and associated teeth found there. The largest centra are said to be 23 cms in diameter. www.flickr.com/photos/sharkspanama/4109437905/in/photostream/Picture doesn't post, but can be viewed at link above. For comparison, 23cm diameter is comparable to or slightly larger than the largest pliosaur vertebrae and again similar to the largest verts by macrophagous ichthyosaurs.
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Post by theropod on Feb 28, 2014 3:04:58 GMT 5
Grey: Researchers, that’s the point. the kind of researchers that actually publish the data we rely on. But is there proper, published data on their methods in this regard? I’m an experienced fossil hunter. I bet you wouldn’t believe me if I claimed I had found a 40cm temnodontosaur vertebra from Lyme regis, indicating a sea monster approaching 30m. elosha11: That’s an interesting find. Are those the largest known centra (and how many are there)? They suggest a size around 13.5-13.6m based on Gottfried et al. 1996 and Caillet et al. 1985, which is also somewhere within the size range of those Ichthyosaurs and Pliosaurs.
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Post by coherentsheaf on Feb 28, 2014 4:28:32 GMT 5
Grey: Researchers, that’s the point. But is there proper, published data on that? elosha11: That’s an interesting find. Are those the largest known centra (and how many are there)? They suggest a size around 13.5-13.6m based on Gottfried et al. 1996 and Caillet et al. 1985, which is also somewhere within the size range of those Ichthyosaurs and Pliosaurs. Afaik the Peruvian verts are larger, around 26cm diameter.
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Post by Grey on Feb 28, 2014 7:49:42 GMT 5
Theropod : I just know that Meg teeth assignement and formula is well known and that only isolated posterior are difficult to use.
I had already seen that centra but never measured it.
Elosha : is there a source that it comes from an associated piece ? The only published associated material I know of comes from Denmark, 20 centras with one at 23 cm associated with an UA that had an original height of 16 cm and 12 cm in width. I've rougly measured it and unless I've made a big mistake, this one does not measure 23 cm, it's merely approaching 15 cm.
Coherentsheaf : Klaus said me that vertebra in the picture was 26 cm, he never said me if it was the largest in the skeleton nor if it was completely preserved.
Megs centras are extremely rare to be found so estimating size using them is unreliable as one needs to be sure the centra found is the largest in the skeleton which appears highly unlikely. Even among teeth I've never heard of Megs teeth of comparable sizes to the specimens from others regions of the world.
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Post by coherentsheaf on Feb 28, 2014 15:31:44 GMT 5
Coherentsheaf : Klaus said me that vertebra in the picture was 26 cm, he never said me if it was the largest in the skeleton nor if it was completely preserved. Megs centras are extremely rare to be found so estimating size using them is unreliable as one needs to be sure the centra found is the largest in the skeleton which appears highly unlikely. Even among teeth I've never heard of Megs teeth of comparable sizes to the specimens from others regions of the world. Same is true for verts of other animals. Nevertheless they are a lot better metric than tooth size. This is e.g. the reason why we tentatively downsized the MoA and P. funkei. They do not have vertebrae we would expect from a 15m pliosaur, even though we only have a few of their vertebrae. Other skeletal elements like flippers would suggest a 15m pliosaur, which I think can reasonably dismissed until further data is found.
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Post by Grey on Feb 28, 2014 15:47:05 GMT 5
Yes, but vertebras from Megs are far more rare comparatively to others species, the reason why no rigorous work or revision could be done based on centras size. Centra are much less common than teeth, and since the largest teeth are exceptionally rare huge centra should be even more difficult to find. Basing Meg size on one isolated centra is pointless given the estimated total number of vertebras in the body of around 200 or more. Also, I doubt the assignements of Megs vertebras is just as known as in pliosaurs. Because of their number and that they are more extensively studied the teeth and jaws datas remain the best alternative.
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Post by coherentsheaf on Feb 28, 2014 15:53:28 GMT 5
Yes, but vertebras from Megs are far more rare comparatively to others species, the reason why no rigorous work or revision could be done based on centras size. Basing Meg size on one isolated centra is pointless given the estimated total number of vertebras in the body of around 200 or more. Also, I doubt the assignements of Megs vertebras is just as known as in pliosaurs. Because of their number and that they are more extensively studied the teeth and jaws datas remain the best alternative. Assigning pliosaur verts correctly wont help. The size of the centra of Kronosaurus varies along the column by quite a bit and has no clear trend. Fossils of giant Pliosaurs are very rare as well. We have maybe 10 or so. Same is true for giant Ichthyosaurs. I think the number of Meg skeletal remains is in the same order of magnitude.
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Post by Grey on Feb 28, 2014 16:01:19 GMT 5
In the case of Meg, the absence of huge centra is assumed because of sampling bias. Centra are much less common than teeth, and since the largest teeth are exceptionally rare huge centra should be even more difficult to find. I doubt the number of vertebras from large marine reptiles is just as rare as the number of Megs vertebras, and this despite the cosmopolitan distribution and very long existence of the shark. The probability of finding the largest vertebra in the largest Megalodon is rather insignificant.
The best option is that we lack the largest elements in the column of the largest old individuals. The second option is that Megalodons grew very large but were less bulky than expected. The last is that large Megalodons were much closer in size to the estimates of Randall in the 70's. I don't think that anyone has seriously taken that one.
There's certainly the same problem of sampling bias in pliosaurs, but much less marked. Large or small individuals, sharks centras are rare or extremely rare respectively.
If fossils centra size was such a solid support at estimating size in Megalodon, no one would rely anymore on tooth and jaws parameters. Which is certainly not the case.
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