Megalodon size

[Grey]

Yes Life

To be honest, I think it is almost 8 inches but not exactly, though it's a matter of mm and relatively meaningless size wise at this scale. I'd say it is possibly at least 198 mm in slant and 150 mm in width. I've already showed it to M. Siverson, he appreciated it.

I'm half convinced for the 20 m mark, I really tend to be cautious until I get more information from the paleontologist who shared these pictures and that I get a scientifically solid comment regarding any size estimate. I'd really like that any new 20 m estimate to be listed and reviwed in litterature.

Sadly, this tooth is in private collection and the owner wants to remain anonymous, so I doubt we'll have ever any proper work on it other than anecdotal referal.

[elosha11]

^Amazing find Grey! But you said the paleontologist you spoke to had made a cast of it and was going to thus try to study it in more detail? Thus couldn't the tooth, or at least the cast of it, be used for further in depth scientific study? Or did I misunderstand you?

[theropod]

Single teeth rarely attract that amount of attention, even scientifically confirmed originals (and no matter how big they are, e.g. there appears to be an impressive number of underscribed giant pliosaur teeth). The number of publications I know that solely describe isolated teeth can be counted on the fingers of both hands (one hand for those dealing with a single tooth), and while some make hints at the approximate size of the animal, none of them produced actual estimates–they mainly use them for their taxonomic utility (out of the question here).

[elosha11]

Good point Theropod. But this tooth's purported measurement should at least be recorded and noted when estimating size based on slant height. I wish its width could be measured too, and its position described. It's almost certainly a UA.

[theropod]

There is no method of estimating size based on slant height. But yeah, its size should be properly recorded, although that alone is rarely used to warrant a whole paper (not sayign there aren’t some papers with about that much in terms of content…). It doesn’t take a scientific study to do that, I just whish there was a common practice of giving reliable measurements (even tough with meg teeth it’s better than with many others on fossil collectors’ sites).
Obviously it’s possible to measure that digitally, all the better since there are three pictures (that could potentially be helpful in finding out error bars for measurements of pictures that seem to be perpendicular).

Apparently those positional estimates seem to have an error bar of at least one tooth in either direction (those are the ranges given for use with Shimada’s method in Pimiento et al.’s papers on the gatun nursery), but yes, based on shape, proportions, robusticity and size it must be either an UA or an anterior lateral.

[Grey]

Apr 10, 2015 22:29:06 GMT 5 elosha11 said:

^Amazing find Grey! But you said the paleontologist you spoke to had made a cast of it and was going to thus try to study it in more detail? Thus couldn't the tooth, or at least the cast of it, be used for further in depth scientific study? Or did I misunderstand you?

He has several casts of it, of various quality. But he will only refer to it in a lecture talk today (Saturday) in Kansas City about the fossil vertebrate marine life of Peru.
The owner of that tooth wants to remain anonymous, so outside of any review, and with the embargo in this country, this tooth won't ever be the subject of a peer reviewed work.

Anyway paleo-artist Alberto Gennari sent me this :



There's probably some perspective though. I'll get more precise measurements soon.

[Grey]

Chilean C. megalodon tooth, 184mm in slant length, approx. 142mm crown height, 122mm wide.



Gentle little fish.

[Grey]

Isolated giant crown

[Grey]

Meg body size trends :

journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9737698&fileId=S0094837315000160

[theropod]

That’s the first study that actually evaluates a large sample of meg specimens and gives an idea of size distributions throughout its population. And

Interestingly sizeable individuals are actually found to be more common than smaller ones. I would have expected a bias towards juveniles, but that is apparently not the case at all considering the principal findings.

[theropod]

Also highly relevant: datadryad.org/resource/doi:10.5061/dryad.6q5t4

Once it’s available this will allow for some interesting insights on the objective of this thread (given the limitations of Shimada’s method, of course, but over a large sample these will tend to cancel out each other).

[Grey]

I know it but somehow it says it is still under embargo.

[theropod]

That can only be a matter of hours or days now.

[coherentsheaf]

Jun 4, 2015 22:59:56 GMT 5 theropod said:

That’s the first study that actually evaluates a large sample of meg specimens and gives an idea of size distributions throughout its population. And

Interestingly sizeable individuals are actually found to be more common than smaller ones. I would have expected a bias towards juveniles, but that is apparently not the case at all considering the principal findings.

Big juvenile populations skewing the whole thing are pretty much ruled out from th beinning given the age structure of lamniform shark populations.

[Grey]

Jun 4, 2015 23:04:20 GMT 5 theropod said:

Also highly relevant: datadryad.org/resource/doi:10.5061/dryad.6q5t4

Once it’s available this will allow for some interesting insights on the objective of this thread (given the limitations of Shimada’s method, of course, but over a large sample these will tend to cancel out each other).

Note this quote from the paper

We did not
exclude any tooth size, as we are not interested
in maximum length, but in quantifying overall
patterns of body size including all life stages
and habitats.