Megalodon size

[Grey]

Wrong, we know the maximum known sizes even more because that's typically what is worked and tested.
T. rex is typically since a while stated at 12 m or so. No need to recall this is not considered as an average size.

But yeah you're right, megalodon was on average 14.5 m or less and Giganotosaurus was 13.2 m on average. You're right. In the meantime I return to exchange mails with real paleontologists.

[Grey]

Coherentsheaf, that is an interesting response, I ll get back at you later.

I'd simply say that depending the regions, 15 m megs can be more or less common, some regions are very proficuents in 6 inches UA.

I would say instead that cross the path of a maximum sized individual, like in any species, would be good luck.

[theropod]

What you believe to be maximum sizes (eg. 13.2m Giganotosaurus, my point on which you unsurprisingly got wrong) are no proper maximum sizes, that's the point. How much they are worked on and tested (and that with very varying results) does not change that.

You can only get reasonably close to an accurate maximum-size estimate (which equals the figures you usually see cited in cases such as C./O. megalodon) if you have enough specimens to see how large big individuals and how big small ones tend to be. We cannot be sure of T. rex' average size, but I want to remind you that 12m is a size figure commonly and inaccurately miscited or rounded for theropods that are smaller or larger than that. It's just a standard-figure that is often used in articles, just like they tend to say megalodon was 15m or 20m long.

Yes, I think mature individuals of C. megalodon most likely averaged at ~14,5m, not 18m. Shame on me. Even worse, I think mature T. rexes averaged somewhere IN BETWEEN 10 and 12.3 metres, and likely not near the upper or lower ends of this. How can someone seriously be as biased as I am? I mean, really? I'm the biggest fanboy on this planet, making such incredibly biased claims!!!!

[Grey]

Temporal, regional, sexual sizes range differences ? Uncertainties of sizes estimates ? Isolated teeth=/=isolated full grown skeleton ? Hard to understand ?

[theropod]

What does that have to do with anything I wrote? Just writing some terms won't bring you any further, especially if it is the 1000th time you tell them. The fact remains that the average mature C. megalodon, the animal you find teeth of, is no 16m+ behemoth, I have already demonstrated this based on a sample of supposedly rather large teeth (and based on tooth width, which is the method usually yielding the highest results).

[Grey]

You demonstrated nothing, you can't when you ignore all these factors.
Tooth width don't give the highest results actually. A long UA can give higher results through Gottfried and Shimada than tooth width.

But your poor understanding can't help you on that.

[creature386]

IMO, this is again one of these debates which depends on definitions (such debates are pretty much impossible to win BTW).
One thinks average sizes represent the animal better the other thinks maximum sizes do so.

[Life]

theropod

Lets just say that a large Megalodon is realistically within 16 - 20 m range and put an end to the argument over size of this animal. Due to lack of properly preserved specimens, it is impossible to figure out average size of Megalodon.

[theropod]

I am agreed with that, however the mere size of a large specimen isn't what necessarily interests me the most in a fossil animal. It makes the potential comparisons one can make to other animals pretty limited in their meaning.

[Grey]

When you'll understand theropod :

-that determine average size in animals known by few specimens or isolated remains is lost cause
-that average size can be a different meaning between different groups

Then we will talk.

But I know that you're UNABLE to retract yourself or at least revise yourself, because that would engage your expectations in the cases of others animals.

[Grey]

coherentsheaf, I'm basically very agreed with you, now like I said, this can be applied to any species.

Blue whales observed in the wild are not all 30 m but that's their potential size range, just like living megs observed 5 millions years ago were not all +18 m (assuming this figure real, which appears very plausible through my communications). I only question the 15 m mark as being "rare" as teeth indicating something around that range are just not that rare, especially if we include isolated posterior and lateral teeth.

If pliosaurs shed their teeth in the manner of sharks and were not known by complete skeletons, we wouldn't find either all the times teeth coming from +12 m pliosaurs. But still such a size remains a very reality of their potential range.
Only, talking about pliosaurs species or megs, we cannot establish anywhere an exact average size because we dramatically lack of datas.

One remark though. I would avoid to discuss at length about the meg skeleton in Peru and its exact size but in any case it is gigantic. That's an indication that finding a gigantic specimen is not extraordinary luck at all. And that's not surprising since teeth over 6 inches in Peru and Chile are known to be very common in this region.
By contrast, the complete set of teeth from Florida owned by Hubbell obviously comes from an individual which died and lose all his set during decay. The possessor is estimated to have been ~12 m long (see Siversson talk). No wonder, megs teeth from Florida are usually not especially large (though I've reported one huge specimen earlier around 14 cm wide).
Now it is possible this particular individual did not die naturally and was killed by a larger meg, pack-hunting odontocetes or disease and thus had not achieved its growth, but in any case we see a massive size disparity depending the regions. South Carolina teeth indicates on the contrary that sharks easily over 15 m patrolled the waters of Atlantic, see Hubbell's tooth about 15 cm wide but also a number of regular specimens over 6 inches long and over 5 inches in width.

That's why I refuse to establish an average size to this very complex and poorly known species with a very long cosmopolitan existence.

[theropod]

Sept 20, 2013 3:11:21 GMT 5 Grey said:

When you'll understand theropod :

-that determine average size in animals known by few specimens or isolated remains is lost cause
-that average size can be a different meaning between different groups

Then we will talk.

But I know that you're UNABLE to retract yourself or at least revise yourself, because that would engage your expectations in the cases of others animals.

The question is, do you understand both those points apply to maximum sizes just as much or more, even tough in a different way than what you probably meant in the case of 2.?

And would you mind thinking about your last line regarding yourself first before posting your usual baseless rant on me? It's pretty amusing every single time, even when you and everyone else can see it was the other way around, I'm the one whom you accuse of that.

I'm gonna retract myself if and when you will convince me with your arguments, not before. Live with it. I'm not bashing on you all the time just because you never retract your views when arguing with me, even tough that is what causes you to do so with me.

[Life]

Sept 20, 2013 1:25:42 GMT 5 theropod said:

I am agreed with that, however the mere size of a large specimen isn't what necessarily interests me the most in a fossil animal. It makes the potential comparisons one can make to other animals pretty limited in their meaning.

This source offers some useful data: www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0010552

However, it is apparent from holistic evidence (worldwide fossil record) that it was not unusual for C. megalodon to approach 16 - 20 (m) TL. Size estimations based on tooth size are conservative in the sense that they more accurately reflect upon the biological ground realities of C. carcharias (not C. megalodon); C. carcharias is assumed to be the "closest living analogue" to C. megalodon but these sharks are not exactly biologically alike (same) and this leaves room for C. megalodon to differ from C. carcharias in the context of size even on pound to pound basis.

Existing fossil record indicates that C. megalodon ranged from 2 (m) to 20 (m) in TL. Within this range, you may regard 16 - 20 (m) TL range as HIGH END for this species.

When comparing C. megalodon with other gigantic animals, it makes sense to consider the species' HIGH END size range. However, if you are looking forward to consider an "average size" for C. megalodon then you will be left with disappointment since such kind of revelation is impossible to determine in case of poorly preserved animals.
So we have to keep all of these factors in mind.

[theropod]

I doubt a nursery were you'll mainly find juveniles and some older females is very helpful for getting a whole species average, but we can gain a good impression by looking at samples of teeth (such as this one: theworldofanimals.proboards.com/post/5281/thread). This should make clear what is a large or normal-sized specimen.

I think we can neither regard the methods we have as conservative nor liberal. We cannot know whether they are either of that. However tooth width ought to be relatively constant and yield a relatively reliable figure. From there it is quite easy to see what size individuals above 10m are typically.

Take this as an example: theworldofanimals.proboards.com/post/5281

All those are considered adult based on their size (in fact, that's a sample of pretty big teeth, all above 6 inches!), so this reflects the mature size range to a good extent. We can see what a large shark is (~16-17m), as well as what a smallish one (13-14m) or an average one is (14.6-15.9m). Of course those merely reflect that sample, but the average C. megalodon obviously wasn't 16m+. Such individuals, as large individuals in any species, wouldn't be very common. Certainly not an absolute rarity, but most commonly encountered non-juveniles are most likely smaller.

That even in a bunch of large 6in+ teeth the average size may just be 14.6m is a clear indication. All of these could potentially be fully grown individuals going by their size, since the smallest are more than 25% bigger than the 10.5m from which on they are considered adult-that's roughly comparable to how much larger Great whites tend to get after reaching maturity. Of course some may not be fully grown. Others on the other hand may have reached full size even earlier, so this is coing to balance quite well. Our evidence tells us the majority of fossil teeth are probably a good deal smaller than these.
Of course, as we can see, there are individuals also here that reach bigger sizes, but the majority of sharks probably remains smaller (see the growth curve of Great Whites in the Symposium [standard works thread]).

When comparing an animal to another species it is most important to consider what you use for comparison based on what is known for both. eg you may well use Carcharocles at it's high end to compare to an extant animal such as an Orca or Sperm whale, known from a sample that's at least as big (more likely this will create a slight bias towards the extant animal, but likely not that greatly considering there are thousands of teeth known, if we ignore freak specimens). We should not do the same with an extinct animal such as a Livyatan, since it's only known from one individual that probably does not represent the upper end of it's size range, and that with a huge amount of probability is not an extreme.

[Grey]

No one knows if Livyatan represents the high end of its species, I've already discussed that, I've enoughly talked of this with its describers.

But there is not much reason to think it was particularly small or average :

-this is not a tooth lost during a lifetime like very most of the megs teeth, this is the skull of an animal which achieved its life

-there's no indication of disease on the remains

-since it is described as an apex predator, it is unlikely this is an animal killed by a predator, no evidence for that

-hence, this is not the case of a sperm whale killed by a whaleship before it eventually got full grown either

-osteology corresponds to an adult (Lambert comm.)

-there is no isolated hint or remains suggesting directly larger individuals

-sperm whales stop growing at one given time, unlike reptiles and fishes

-one skeleton represents an average : by this logic the unique isolated meg skeleton, recently again described by Hönninger at almost 19 m, must be an average too then...


No one rejects the possibility of finding a larger animal but now keep these facts in mind. And beware with enthusiastics expectations. And keep in mind that the exact size for this individual is not conclusive at now.

Regarding meg size, you still oversimplified and ignore my last points...

One word on the nursery ? I remark that on very few specimens considered as "adults", one individual is ~ 17 m TL (according to Shimada, quid of other methods...). That's not exactly an "extraordinary" or "unusual" occurrence like a reported 7 m white shark off KANGA Island.

And we ignore by how much of time these adults megalodons individuals are spaced in the nursery...