Megalodon size

[theropod]

Isn't Jeremiah's method for upper anterior tooth width? If so it cannot work with lateral teeth without producing an overestimate if those are proportionally wider, so no problem with that width.

[Grey]

It depends the lateral tooth. The L5 is usually typically as wide or wider than the UA. So an estimate based on a tooth which is not the widest in the dentition produces a conservative estimate (see Siversson's mail page 2).

[theropod]

It is apparently wider, so a method for UA width will produce overestimates if used with a width that's bigger than the UA width.

[Grey]

You've confused. Jeremiah's method is based on the widest tooth of the dentition, not the width of the UA itself.

The purpose of this method is determine the jaw perimeter, so the best if to look at the widest tooth, a narrower producing underestimate. Check the mail by Siversson I said.

[theropod]

dunno which mail you mean, but:

Root width

In 2002, shark researcher Clifford Jeremiah proposed that total length was proportional to the root width of an upper anterior tooth. He claimed that for every 1 centimetre (0.39 in) of width, there is approximately 4.5 feet (1.4 m) of the shark. Jeremiah pointed out that the jaw perimeter of a shark is directly proportional to its total length, with the width of the roots of the largest teeth being a proxy for estimating jaw perimeter. The largest tooth in the possession of Jeremiah had a root width of about 12 centimetres (4.7 in), which yielded 16.5 metres (54 ft) total length. Ward asserted that this method is based on a sound principle that works well with most large sharks.[12]

en.wikipedia.org/wiki/Megalodon#Size_estimation

As I noted eralier, this method lacks proper documentation.

[Grey]

This method has been used by Henry Mollet and Brett Kent on C. carcharias and P. benedeni. Mike Siversson and David Ward use it too.

That post, that was really hard to find ?
theworldofanimals.proboards.com/post/1371/thread

theworldofanimals.proboards.com/post/1412/thread

[theropod]

And yet, there is no paper describing the method properly. You should correct the error in Wikipedia if it is really about the widest tooth, not the upper anterior.

Am I now supposed to know where every single one of your screenshots was posted?

[Deleted]

There is apparently a Megalodon skeleton in Peru that is said to be ~18 meters long.

I would take that figure over any and all figures obtained using teeth.

[Grey]

I've said you the mail page 2 in my posts, not a big task.

The method is used in several papers by sharks specialists authors (but they are certainly wrong !) about the white shark and the extinct "false mako".

[Grey]

Jul 9, 2013 22:17:43 GMT 5 @brolyeuphyfusion said:

There is apparently a Megalodon skeleton in Peru that is said to be ~18 meters long.

I would take that figure over any and all figures obtained using teeth.

That was in my post, I'm in contact with the discoverer since two years. I'm confident in it, but don't use it as it is not published.

[creature386]

Jul 9, 2013 22:17:43 GMT 5 @brolyeuphyfusion said:

There is apparently a Megalodon skeleton in Peru that is said to be ~18 meters long.

I would take that figure over any and all figures obtained using teeth.

I too would, if it gets finally described.

[Grey]

A short testimony of the tooth width method in this article :

eicheworldview.blogspot.fr/2011_05_01_archive.html

[theropod]

Jul 12, 2013 2:28:25 GMT 5 theropod said:

so far we always assumed the measurements and figures in Gottfried et al., 1996, to refer to slant height.

HOWEVER
In Gottfried the following is stated:

All tooth height measurements given are the maximum height of the tooth, measured as a vertical line from the tip of the crown to the bottom of the lobes of the rooth, parallel to the long axis of the tooth.

you can see the vertical green line here, indicating the long axis:

and the upper black mark indicating the maximum lenght of the tooth along it.

So this makes the size-estimate situation even more difficult, since we have no comparable figures for some of the biggest specimens (eg. Bertucci's tooth), and cannot easily apply gottfrieds methodology to them.

Also another point in favour of the root-width method since that's a much less problematic measurement.

By this measurement, Gottfried's 168mm tooth is only 3mm shorter than Hubbels tooth (18,4cm/7,24in in slant lenght and 17,1cm/6,75in in perpendicular lenght), which makes sense considering it was supposed to be the "biggest tooth available".

It seems doubful whether the direct-sizing or Gottfried-based figures proposed in this thread are correct, since slant "height" is a bigger measurement than the lenght Gottfried seems to have used and based on.

Luckily we have the measurement for Hubbels tooth, which by any standard is a very big specimen, tough not the world record (please post if you know a photograph or measurements of the 19,4cm Bertucci's tooth). Also important to note that slant height doesn't appear to be used in any publication, perhaps because it isn't actually height but a rather random measurement, so this isn't all that surprising.

Using this specimen's perpendicular height of 17,1cm the owner would be 16,4m long following Gottfried's regression, based on linear scaling from the sample (avg. 5,5m, 5,92cm) 15,9m.

The 6m shark would make the specimen 17,1m long, and the two large individuals (6,4 and 6,6m with 5,9cm UA2's) 18,5 and 19,1m long.

The above is probably not very meaningful anyway since tooth height is not the best predictor in two animals with differently elongate teeth, however it should be kept in mind when extrapolating sizes.

[elosha11]

Jul 9, 2013 22:27:08 GMT 5 Grey said:

Jul 9, 2013 22:17:43 GMT 5 @brolyeuphyfusion said:

There is apparently a Megalodon skeleton in Peru that is said to be ~18 meters long.

I would take that figure over any and all figures obtained using teeth.

That was in my post, I'm in contact with the discoverer since two years. I'm confident in it, but don't use it as it is not published.

According to Honninger, the skeleton was originally measured at 18.43 meters but after further inspection was revised to 18.26 meters. If that is accurate, the living shark was almost certainly longer than its skeletal length, possibly exceeding 19 meters. The entire jaw and associated teeth are also part of the discovery. If this is fully described and accurate, it should help put to rest all of the conflicting theories as to how to measure Megalodon (and perhaps other mega-toothed species) based on their tooth size. We will be able to accurately compare the various measuring theories and see how they measure up to the full length of the fossil. If the two other Megalodon skeletons are also fully described and contain full sets of teeth, this will provide a larger size sample and will further bolster the correct way to measure the shark's length based on tooth size.

Of course this is contingent upon the discovery actually ever being published...

[theropod]

^If it doesn't get published that would be a desastrous loss. We can only hope they find a solution or at least collect as many data as anyhow possible.