Megalodon size

[Grey]

Very sensitive explanation by Kent :

[Grey]

Mail from Brett Kent about why meg was most likely the largest top predator in existence, educated opinion about L. melvillei size and Gottfried's tooth measurement (sounds like Theropod is right after all, though I'd like more statement as Brett himself does not seem that certain either).

[Grey]

Let's try to get estimates for the meg tooth with 20 associated centras found in Denmark described 1983.

The tooth was estimated originally to have been 16 cm high and approx. 12 cm wide. On the 20 associated centras, the largest was 23 cm in diameter.

For the tooth, assuming the length was measured perpendicularly, using Gottfried's regression, the meg was 15.14 m TL.
Assuming Jeremiah's calculation, the meg was approx. 16.44 m TL.

Using isometric scaling based on great white vertebras (probably just as, or more debatable than figures based on teeth(?)), from a 5.57 m TL great white with the largest vertebra measured at 8.3 cm, this results in an approx. 15.43 m TL meg.
Using the largest vertebra at 8 cm of the Cojimar female, if it really measured 6.4 m,, this results in a meg of about 18.4 m TL. If we merely list 6 m for the Cojimar great white, this results in a meg at 17.25 m TL.

In both cases, this is indicative, and I don't know the reliability of estimates based on vertebras. But based on these examples, we can hypothetically expect for this meg a body size in the 15-18 m range.

However, note that the 23 cm vertebra was the largest of the 20, and most likely not the largest of the complete column. Same for the tooth, I've not found which was its clear position.

By sheer cautiousness, I've not used the vertebra measurement from the peruvian skeleton at 26 cm...

Even if we conservatively attribute 15-16 m overall for the specimen, this unique material was the first evidence of megalodons in Denmark. And still, the very first specimen was probably at around 15 m or more. This is somewhat again confirming my claim that megs that large were not that rare, since this first and unique specimen is obviously not in the 10-14 m category. This can be added with peruvian discovery which certainly represents too a large or very large specimen.

In short : megs above perhaps 15 m were anything but a sheer rarity and to found large individuals from a species in fossil records, even in unique specimens, is very possible (cf : L. melvillei).

Sources : elasmollet and "Carcharodon megalodon from the Upper Miocene of Denmark".

[theropod]

If I understood it right, the total lenght on the regression above is 0,73+0,12*tooth width(mm)

For a 120mm tooth that's 15,13m, not 16,44m (16,33 is yielded by a 13cm tooth and 17,05 by a 13,6cm one)

The result appears closer to the 1,25*TW from the museum width table once posted.

If the 1,37*TW(cm) is accurate "for all lamniforms", what did I overlook, since this makes it look like it definitely isn't when based on the great white?

[Grey]

Brett actually drew a midline in the sample of these great whites, not properly using Jeremiah's value. But the results on the midline are roughly corresponding with Jeremiah's results, with the beginning at 25 mm TW exceeding Jeremiah's value (1.48 instead of 1.37). I made a mistake when stating this as Jeremiah's method scatterplot, this is simply the middline in a sample of great whites from Mollet website.

Brett agrees that there is an error in Renz book when it is listed that a 12 cm TW results in a 15.5 m meg, whereas 16.4 m appears to be the good measurement.

Don't forget however that tooth width is useful not only in the great white, but the methods actually works with other lamniforms as well.

[Grey]

From Mike Siversson about tooth height VS tooth width.



Note : the method based on tooth width is going to be published within the paper about Cardabiodon.

[Grey]

From Brett Kent :

[blaze]

Did the screenshot get corrupted?

Edit: it was an error on my part it seems.

[Grey]

Which one ?

[blaze]

The one you had just posted, it appeared all black but I think it was an error on my side, a refresh fixed it.

[Deleted]

Does anyone have any info on the size of the Megalodon vertebrae(not the ones Klaus found in Peru)?

iirc, there were also some Megalodon vertebrae found(again, not talking about Klaus' discovery)

[Grey]

There are very few found.

The largest published was 230 mm found in Denmark in 1983 with 19 others vertebras and one associated upper anterior tooth (about 16 cm high and 12 cm wide). Since this is only the largest of the 20 associated, and that according to Gottfried et al. meg had around 200 vertebras, this is perhaps not the largest in this particular individual.

Source : "Carcharodon megalodon from the Upper Miocene of Denmark".

[Deleted]

Aug 1, 2013 17:20:51 GMT 5 Grey said:

There are very few found.

The largest published was 230 mm found in Denmark in 1983 with 19 others vertebras and one associated upper anterior tooth (about 16 cm high and 12 cm wide). Since this is only the largest of the 20 associated, and that according to Gottfried et al. meg had around 200 vertebras, this is perhaps not the largest in this particular individual.

Source : "Carcharodon megalodon from the Upper Miocene of Denmark".

Thanks.

We could probably get a lower bound estimate by assuming that it is the largest in the entire individual though.

[Grey]

You welcome. Yes, that's what I did in an earlier post : theworldofanimals.proboards.com/post/4916/thread

The problem being that here too, it seems that vertebra width exhibits variations the size of the shark. A 5.5 great white can have slightly bigger vertebras than a 5.8 m individual.

But overall, if we acknowledge this centra was the largest of the whole column (unlikely IMO but whatever), this meg was overall 2.5 times longer than the large white sharks individuals.

[Grey]

Brett Kent about the size patterns in marine carnivore hinted by McHenry in his doctorial thesis, and regarding the report of a 20 m whale shark :