Megalodon not as big as we once thought!

[Semyon]

(02-07-2022, 11:08 PM)GuateGojira Wrote:

(01-23-2022, 06:47 AM)Ediacaran Wrote: Interesting discussion in response to Perez's 2021 publication that dealt with Lamniform body size estimates.

https://twitter.com/Dinoh555/status/1370043407041724420

And this is what happened with Megalodon during all these years! One people put a paper with an estimation, latter other people shows that is incorrect, other put other paper and latter is debunked. The size of this shark is very problematic as there are only teeth and a very few vertebrae that managed to be fosillize. 

The conversation is very interesting and try to refute those estimations. Using Cretolamna, they propose a maximum size of 13.2 m and 20 tones for the largest known tooth by scientists and of 14.6 m and 27 tones for the largest tooth in private record. Of course this are just the estimations of a few posters there, but they suggest that the work of Dr Shimada is more reliable.

Who knows what will say the next document about this giant shark.......

(06-28-2022, 10:34 AM)AndresVida Wrote:

(06-27-2022, 07:31 PM)Semyon Wrote: An outlier is the 24 m male Physeter in a sample of 500 000 (McClain 2015). GHC-6 is certainly not as exceptional as this, especially when taking into account the regional size differences (Pimiento 2015, Shimada 2022).
The 20 m data in Perez et al. is itself somewhat conservative being the mean of the range (17.4-24 m) and using the lowest regression available here.

20,3 was actually the alleged mean of such range, but the same study mentioned that the 24 m long estimate is an exagerration derivied from error (very common when you have one of the most fragmentary animals on the planet of which you don't know it's true proportions and the rest is just nice speculation)

*This image is copyright of its original author

Source : https://www.researchgate.net/publication...dentitions

I don't buy 24 meters either, 19 - 20 m seems more reasonable.

And yes, even if the 24 meters long estimate is real, ghc-6 would still be an outlier since it is crossing the max reported size range of megalodon just quoted at 19 - 20+ meters. It doesn't matter if there might be an even larger individual out there, always using the leopard example a 91 kg leopard is an outlier just like the 98 kg male from north Iran since both have reached the max reported size of this species.
So no matter if there's an even 24 meters long megalodon out there, any megalodon reaching the max reported size is therefore an outlier specimen.

For a female cold water Otodus Megalodon offhand

13-14 m would be below average probably immature or exceptionally small females
15 - 16 m would be average
17 - 19 m would be large
20+ meters would be exceptionally large where the largest specimens (aka outliers) can be found

I'm actually quite agreed, but you certainly jump to premature conclusions as no new global review of size distribution in Otodus using the newer SCW method has been done yet. It is not impossible that we underestimate a bit the size of the Otodus genus, the backbone from Belgium was estimaged using centra diameter (155 mm) compared to white shark centra that it came from a 9.21 m megalodon (Gottfried 1996, Shimada 2019) however work by Catalina Pimiento and on going work by Jack Cooper indicates the Belgian backbone is actually 11.1 m on its own, almost 2 m longer than the previous estimate for the whole shark.

Cooper article should come out soon, but there is this talk last year https://youtu.be/X4FA45QwlIA

Spoiler : they estimate the whole shark (adding chondocranium and caudal) at 15.93 m.

As you see in the talk, this seems to confirm to solidity of the SCW method over Shimada's equation.

Using this, the largest reported megatooth centra in the literature is from some Danish material, today unfortunately discarded, described in Bendix-Almgreen (1983) as 23 cm in diameter.
Simple scaling from the Belgian 11.1 m backbone gives in a 16.5 m long backbone so the correspondingly whole animal..

But before arguing about anything I'd prefer to wait to see the feedback on Cooper's article, as well as we'd need an updated size distribution review for the genus.

Again by outlier I meant a freak, a 20 m bull sperm whale is not a freak to me, the purpoted 24 m male from McClain's review would be.
As the SCW method proposes several 18-20 m individuals in Shimada 2022, 20 m does not make it the Robert Wadlow of the genus.

I don't buy firmly the 24 m bull Physeter from McClain but the report seems relatively reliable and being the longest individual among 500 000 would make it an normal outlier, marge jawbones from comparably sized individuals are reported in the literature.
Even so, we know that Physeter can physically reach 20.7 m so I would not consider it a freak, just like there is nothing to say Sue and Scotty are freaks on their kin. Reply