Megalodon size

[theropod]

On individual sizes, and among these individuals the largest represent the largest size known or estimated for the species.

Your quote of Zhuchengtyrannus talks about the size range, not any specific average size for Tyrannosaurus and Tarbosaurus. They say it enters the size range of others large tyrannosaurids. Like Kent's chapter where he says that the Cetorhinus and Rhincodon are comparable to megalodon in size. He does not say they can reach the upper sizes of meg (though for Rhincodon it's debatable), he does not say they are equal to the average size of megalodon, he says the enter the size range known or estimated for megalodon.

It sais "equivalent in size". I don't exactly see how an animal that's obviously smaller (perhaps even on average, but that needs to be studied more) can be stated to be equivalent based on maximum sizes.

Ok, assume that was just supposed to mean "reaching the same size range", that still proves my point that scientists do not automatically assume a species with bigger known maximum size to be bigger, neither do they assume maximum (known) size was the only relevant metric.
Tough I suppose "comparable" in the context of Kent's work means "the closest we have today", not the same as "equivalent".

I don't compare the size range in very sexually dimorphic species with an animal known by a single specimen plausibly representing a male. So I separate genders. Livyatan is, in the paper, stated in the size range of adult bull Physeter. So compare it with the size range of bulls, not cows.

Well, at the lower end of it's size range it is closer to a cow in size. Were you may most probably place it depends entirely on that, and will thus be irrelevant to the size of the taxon.

I also find that logic quite strange. We don't know anything about it's gender, it is of UNKNOWN sex, and yet you choose to just compare it to one of them?

I won't do it for you (size of mature female GW, size of average female GW and maximum size of female GW= proportionally larger variation than in adult full grown bull Physeter).

The variation in mature great white sharks does not appear to be greater than that of adult physeter, neither is what has been presumed by Gottfried (which is in fact broadly comparable to Physeter's size range).

If meg biology and life history appears to have significant difference with the white shark, your basis on Gottfried works becomes potentially worthless.

And we don't know for sure whether this was the case, and if, we don't have any clue of it's effects, so (as you yourself claimed when it was about the weight, were Gottfried was relatively liberal) these assumptions are best to use.

Stop growing at 13.5 m ? That's odd then that several sizes estimates based on this table from Gottfried yeilds sharks at 15.9 m, 17 m and perhaps 20.3 m...

That's what I wrote!

Yes, assuming the shark matures and grows like a great white, a shark that matures at 10,5m should stop growing at 13.5m, of course with a huge scope of variation.

I think we have already made sufficiently clear during previous debates why the 20.3m figure was more or less worthless considering it based on a single, unusually proportioned and inaccurately estimated great white individual.

Again, some C. megalodon specimens still grew after they reached 13.5m (the approximate point where they would on average reach physical maturity based on Carcharodon). Others are going to stop growing earlier, this is an AVERAGE, not a lower bound. The average size of physically mature individuals will be somewhere above that, and in all likelihood below 15m.
The point remains that 16m and above are very large specimens, and they have always been treated as such.

And whatever, meg is not a white shark.

Nobody sais it is, not even Gottfried et al., even tough they viewed it as a similar animal, due to the suggested phylogeny at the time(becoming more and more unlikely now). Still, the white shark is proposed and used as the most likely analogy by most experts, and we probably have nothing better than it.
All the time you are just criticising what I'm doing wrong (and what all the experts are apparently doing wrong too!) instead of offering anything better or even close to being as good.
If you cannot offer an alternative, don't complain!

The sperm whales reported were all mature but possibly not all fully grown as they were killed and not animals that achieved their life the Livyatan holotype.

Animals dying of old age are pretty rare in nature. We just know it seems to be completely adult, not whether it is on the upper or lower end of the range adult physeteroids are in.
Anyway, that's a bit as with shark growth then, even tough at some point rather late (average of 15.9m in males, not sure about the females, but that's certainly much lower) Physeter stops growth.

At first, it is almost impossible that 30 m, 200 tonnes active macro-predators lived in the Earth trophic systems. This kind of figures is for SF amateurs and kids.

That was a hypothetical point, not a suggestion that they did. Anyway, you just agreed with me, it's improbable, even tough it has not been proven to be impossible. These two are different things.

Livyatan type could be an average specimen but as well it could be a large one because of the points. Based on indications that it was an adult which achieved its life. based on the total absence of isolated material pointing toward larger specimens.

We are talking about adults that achieved their lifes. There's a reason there is an average size and not simply a fixed figure at which sperm whales stop growing. Adults, even males still show variation, that's why we see ones in excess of 18m (some even 20) and some probably below 14. The same is of course true in all animals, specimens are not uniform in the way they grow and mature.

And the variation of large lamniforms doesn't seem to be any greater than that between adult Physeter.

Well, that's just what I wrote. But at 13.5 m it could also represent a female. But again, I'm not interested in these meaningless speculations.

Then why keep doing them? I already told you all this, so we'd better put this point to rest since we even agree on it.

No, I've highlighted you the points that could also make think it was more in the higher range of its species. I've not argued anything about Livyatan size status. That's your job.

It's certainly not my job, and I'm seriously getting tired of always having to do it, neither is it yours of course, and I can imagine you feel the same way. There are other people who have this exact job, but it will certainly take losts of time to collect a decent sample of Livyatan.
These points all rather point out to it being fully grown, not more. It can be on the high or the low end. Eg. assuming it's a male, and it's about the same average size of a male physically mature Physeter (short of 16m, again, with a big scope of variation since you like to disregard this simple truth), it is likely that the biggest or smallest individuals were just as much bigger or smaller as in Physeter, perhaps it's more or less, but that would be entirely speculative.

Any you have argued a lot about "Livyatan size status". you regard it as having maxed out at the size reported from just a single individual!

I always discuss what we know, not what we don't know, contrary to you.

So why are you even discussing then? Obviously just what we have physical evidence for is not always meaningful.

Do you know "All yesterdays"? From what I heard that book may help you understand the place speculations have in palaeontology. The next step for you would be to understand when a speculation should be preferred over a less probable one, even if that less probable speculation is what you cannot comprehend to be one.

So you start speculating it was a female with the same sexual dimorphism than in Physeter ? In the goal to speculate about +20 m Livyatan in your next step ?

Oh for god's sake, how paranoid can someone get? You see something you don't understand, and your response "you fanboy! you...."

And that's curious how you use the particular biology of Physeter (unique huge sexual dimorphism) or reject it in other occasions (template as size/proportions).

We know the size and proportions of other physeteroids likely closer to it. We do not know their growth rates. unless we have better ones, their growth rates also have to be based on it. After all, you also base Meg's growth rate on other sharks, don't you.

If so, you're really not objective.

You do. You argue to know the average size of megalodon. But actually no one knows.

I argue to have a reasonably good idea of it, not to "know it". EDIT: It turns out, a way better idea of it than you, even tough I myself appear to have been too liberal:

Maximum size known.

Which is pretty much irrelevant if a species is know from too few individuals, since it is very far from the actual maximum size in all but very unlikely cases.
EDIT: So, following recent statistics, the probability of a 17.9m megalodon lies around 0.2%. Even if we only count specimens above 10.5m, the probability is only ~0.4%.- That means the likelyhood of a single, random individual being this large is that small. and that’s only slightly larger than the upper estimate for a specimen of Livyatan that currently still represents the expected value for its species…

An update of mine, I don't say it is more likely to be a large individual than an average one, but that the probabilities are similar.

I apreciate that, that's a step in the right direction. Now if the probabilities for average, large and small are the same (which depends on the population structure of course, but in normally distributed populations it’s unlikely), where does that leave us regarding the most objective assumption?

Have I said a 18 m meg is average sized ? Have I said Livyatan was average sized ? No, we don't know the intraspecific variations. Period.

Then I find it really curious that you still insist in saying megalodon was larger, just because an 18m Megalodon is likely bigger than the Livyatan holotype. You should have the ability to say that you don’t know which is larger either, if you don’t know these.

The points by Siversson, Kent and others I've talked with are not speculation but observations on the extant datas. Observations that I had made myself before discussing with them.

Observations whose interpretation is speculation, speculation that both you and these authors happen to agree on, tough perhaps for different reasons.

Actually you can convince me on some matters where NO SPECULATION is involved, like the actual scientific measurement of sharks teeth (I guess you're proud of that case).

A very rare case indeed, you won't find many like that one. And would you please either thank me for pointing that out or at least stop always making fun of me just because I was demonstrably right and dared to stand up to you when you tried to deny it?

But I cannot convince you of anything, you have a gigantic ego and really think to have superior skills in any paleontological field. That's why I don't feel any pleasure discussing with you.

You can convince me of things, and, though rarely due to the way you present your arguments, you have done so in the past. I rather get the feeling that I’m the one who cannot convince you of anything, and that’s not because of the evidence.

Nearly is quite a difference. And I much more appreciate to discuss with coherentsheaf, despite we sometimes share opposed views, than with you, you should wonder why.

Because you don't like me. Because coherentsheaf is a scientist whom you have more respect for. Because you could never swallow your stupid beliefs about me, and because what I argue personally hurts your feelings about your favourite animals.

Obviously I don’t have his level of expertise in some matters, but neither do you, so that would be a hypocritical reason. I don’t even expect you to trust me to the same degree, I don’t care about that. But I have got the right to be treated with respect regardless of what your feelings towards me are.

That's no offense, that's my tastes, the structure of your posts is not appealing to read IMO. And I don't appreciate how you regard paleontology and your overenthusiasm, typical of the psyche of a teen male (bigger, bigger, bigger...). That's at least what I feel reading you since a while.

Then I'd suggest you to keep your tastes to yourself, because they are offensive. That is, unless you also want to read about mine, but I think you don’t. Your grudges don't interest anyone.

That's your opinion and I'm fairly sure it is most likely wrong because you ignore the contradicting factors I've listed in both cases.

That may be the case, which has nothing to do with it's justification. Of a sample of large C. megalodon the average size is defintely below 16m, and more probably below 15m. Up to now nothing better has been proposed.

Here is a speculative statement : Livyatan has a comparable average size to megalodon.

Here is an actual scientific statement : Livyatan is in the size range of adult megalodon.

Well, I'm totally fine with that, just don't speculate about one being larger then, when you are fully aware of the factors making that impossible.

[Grey]

I don't have time and energy to waste to respond your whole post theropod, though some of the first responses are not that bad but I'm not interested at all to respond it. Some of the other posts are just the same usual crap that I barely take time to read, stop to lose more time.

Only that :

Observations whose interpretation is speculation, speculation that both you and these authors happen to agree on, tough perhaps for different reasons.

Totally wrong, the observation of these authors is based on the actual datas available about these species. One reach probably larger sizes than the other as far as we know for now. Period.

"Of a sample of obviously large C. megalodon the average size is defintiely below 16m, more probably even below 15m. Up to now nothing better has been proposed."

Nothing has been proposed at all about megalodon average size and because of all the factors and uncertainties, it is impossible to establish an average size of a species that roamed during almost 20 millions years with its significant size increasing and regional particularities. You're making up a non extant data.
Nothing has ever been proposed regarding the precise average adult size estimate of C. megalodon. And I don't have souvenirs of precise average size statements like known in modern well studied species. But of course, you're a genius. You had even described the paratype of Livyatan at 20 m, before it is even published. Yeah, that was a time ago and you ignored what was a paratype but that's for demonstrate how much you adventure yourself in speculative worlds, only leaded by your overenthusiasm.

"Well, I'm totally fine with that, just don't speculate about one being larger when you are fully aware of the factors making that impossible at now."

You don't understand the statement : "Livyatan is in the size range of adult megalodon". It means that it enters the size range known for megalodon, it doesn't say it is as large as megalodon.

It is therefore likely, but not demonstrated beyond all doubt, that megalodon was larger than Livyatan.


The highlighted part should satisfy you and I'm totally agreed with that part.


Now keep your world with your own rules and principles, and don't discuss with me, I won't discuss with you.

Just contact me once you've excavated a partial skeleton of a 200 tonnes sauropod, a 20 m Livyatan and several tens of megalodons skeletons allowing to get a precise idea of the average size variation within the species. That will change of your baseless blabla.

[Deleted]

I prefer to compare Livyatan specimen with notable megs specimens individually, not to loosely calculate an average range because of all the uncertainties for the already proposed figures and the various factors I've listed above.

I would agree as I said above I don't think average is applicable for megalodon.

some paleontologists I've talked with considers 13.5-14 m to be the most probable size.

Well I agree with them.

[theropod]

Totally wrong, the observation of these authors is based on the actual datas available about these species. One reach probably larger sizes than the other as far as we know for now. Period.

You did not read what I wrote, you jsut read the word "speculation" and filled in the rest...

Nothing has been proposed at all about megalodon average size and because of all the factors and uncertainties, it is impossible to establish an average size of a species that roamed during almost 20 millions years with its significant size increasing and regional particularities. You're making up a non extant data.

I'm not making them up, that's what you have to comprehend.

You had even described the paratype of Livyatan at 20 m, before it is even published. Yeah, that was a time ago and you ignored what was a paratype but that's for demonstrate how much you adventure yourself in speculative worlds, only leaded by your overenthusiasm.

Again, you apparently didn't know what a paratype was either, otherwise I have no doubt you would have corrected me with some snide remark, and after all you where the one who even informed me of a potentially bigger specimen, which I saw no reason to not believe in due to your very badly phrased arguments against it (you basically used the argument of individual variation, not continuous tooth growth).

You don't understand the statement : "Livyatan is in the size range of adult megalodon". It means that it enters the size range known for megalodon, it doesn't say it is as large as megalodon.

Neither does it say it is smaller, which you seem to take as some sort of default condition.

It is therefore likely, but not demonstrated beyond all doubt, that megalodon was larger than Livyatan.


The highlighted part should satisfy you and I'm totally agreed with that part.

I've got no problem with the highlighted part, just with the "likely", which it frankly isn't, that's just speculation.

Just contact me once you've excavated a partial skeleton of a 200 tonnes sauropod, a 20 m Livyatan and several tens of megalodons skeletons allowing to get a precise idea of the average size variation within the species. That will change of your baseless blabla.

Very funny.

@broly: You should read what coherentsheaf has posted on that matter, 13.5m is probably slightly underestimated even based on the Physeter-sample, since it doesn't exclude two outliers. I just repeated the same calculation, with the same result. livy.ods (19.09 KB)

[Grey]

"I've got no problem with the highlighted part, just with the "likely", which it frankly isn't, that's just speculation."

No it is because to now there's no indication the physeteroid reached +18 m, whereas this is very plausible for megalodon. Hence, likely.

[theropod]

We just know it is well within Megalodon's size range, and it's similar to all that we can predict for it's average size (14-17.5 vs 14.5-15.9m), so they could have reached comparable maximum sizes too (because both full-grown physeter AND mature sharks display immense variation, and there is absolutely NOTHING indicating a single fully grown specimen to automatically be a particularly large one-you don't argue that in T. rex regarding Sue, do you?), but there is no need to speculate if you don't whish to.

And didn't you state on youtube 15m was "a typical size for megalodon"? And elsewhere that this was a good estimate for the Livyatan holotype?

[Grey]

There's no indication that the whale reached over 17.5 m (and 17.5 m does not constitute a certain prediction.
This is plausible that megalodon exceeded 18 m because of some huge isolated teeth,, so there's, for now, a greater likelihood that the shark grew larger. There's no speculation there.
I had read a post of you on Carnivora where you wrote something very similar.

[theropod]

It's possible you did read such a post, my understanding of these matters has changed over the time (which is the reason why in some old posts you'll see me comparing maximum sizes, even tough I've tried various means of comparison and have had many discussions) so I'd recommend to look at the date. It's also possible you just misunderstood me tough.


I rest my case but stay on my position.

[Grey]

The post was quite recent and I did not misunderstood it.

I care less of your position regarding megalodon size and many other paleontological subjects. Epic speculator.

[theropod]

That line was incredibly redundant and impolite, tough not unexpected.

Could you give me a link to that post you have in mind?

[Grey]

Update of Pimiento et al.2013, with new specimens and sizes estimates. Note that the new largest individual in the nursery is listed at 17.9 m TL using Shimada's method.

stri.si.edu/sites/publications/PDFs/STRI-W_Pimiento_et_al_2013_Sharks_and_Rays_from_Gatun.pdf

[creature386]

Great finding Grey! Looks like the idiots under my marine predators video won't be happy with that.

[Grey]

Indeed creature, it seems that regarding meg, we have to look forward Pimiento, it seems that she works extensively about megalodon biology.

[theropod]

It seems there were much more really large specimens present at that location than thought...

[Grey]

So let's see again the various modern sizes estimates for megalodon, excluding Randall, the old 20th century estimates and fossils collectors methods.

Gottfried's regression in 1996 predicts a conservative ~16 m TL for a large adult female megalodon from a 16.8 cm in total height tooth. They also hypothesize from that tooth through direct sizing with modern very large white sharks measurements a maximum of 18.2-20.2 m TL. The potential error, given the uncertainty of the size in the largest white shark (revised from 7.1 m to 6.6 m) and the direct measurement make these figures only hypothetical, even though they still use the same tooth specimen. The regression of Gottfried is hard to use on the very largest isolated teeth known since these teeth are usually measured in slant height, not in the adequate vertical height. Essentially, it was reported in a later paper referring to Gottfried that meg was three times the length of any white shark.
Shimada's method in 2002 predicts for the same tooth owner a size of 15.1 m. Pimiento using Shimada finds a tooth belonging to an adult individual estimated at 16.8 m, and in 2013 two new adults specimens, one estimated at 17 m TL, the other at 17.9 m TL. Shimada's method is even harder to use privately on isolated teeth than Gottfried's since it needs precise measurement in the crown height of the tooth and its exact position in the jaws. However, it demonstrates that a number of small posterior/lateral teeth can easily belong to unexpectedly large individuals.
These estimates are based on the largest specimens available at the time in each field of study and may not reflect the largest individuals.
Siversson did not properly published something yet about this, but calculating upper jaw perimeter (already used by Kent while estimating size in Parotodus benedi), using data in moderns lamniforms, the complete set of teeth owned by Gordon Hubbell and larger isolated teeth, estimates a maximum size of almost 20 m TL, though it remains unknow which specific tooth he used (except for the Atacama specimen seen in one of his talks).

Awaiting mails from some of these authors, and new specific works. In the absence of hard data on meg's anatomy, this is the best we have at now. In anycase the fish was almost unimaginably huge from a modern and evolutionnary perspective.