Megalodon size

[theropod]

The above is undoubtedly a very big specimen, but world record appears unlikely. The tooth is 17,27cm (6,8in) tall perpendicularly and 17,97cm (7in) in greatest (slant-) lenght and 14cm (5,5in) wide in greatest width, which is roughly comparable to Hubbel's tooth. It however reaches 7,25 inches when measured along the ruler and up to the point were the rulers meet (18,4cm).
I'd be very cautious regarding the supposed erosion on the fossil, and it appears unlikely this would have accounted for a whole inch. Among the biggest we have without a doubt, but not bigger than Hubbel's or Bertucci's tooth.

[Grey]

In direct slant height, I get around 7.5 inches, which roughly corresponds to Bertucci's tooth.

Now, whatever since I'm more interested in the tooth width...

[Grey]

Found the archives of MegMawl with 6 and 7 inches teeth :

web.archive.org/web/20070929140640/http://megmawl.com/6inch.html

They report a 7.62 inches tooth from a private collection in New England and a stolen 7.5 inches tooth from the Museum in Lima (this country is definitelu terrible for paleontology).

Also, given the professionnalism of the restorations, I wouldn't be critic with the using of some of these teeth for scientific estimates, since they criticize themselves the restorations of some original teeth to make them larger.

[theropod]

CMU7843R is 19,2cm (?in slant supposedly) long and 13,7cm wide, so this is perhaps the second-biggest tooth known, only short of 2mm shorter than Bertucci's, however only as wide as Hubbel'sEDIT:it appears Hubbel's is significantly wider than what I recall was given here earlier.
This also means it might actually be taller than Bertucci's tooth in perpendicular height, if it is nearly as tall in slant height despite being relatively elongate.

Using the root width formula from the great white regression reported by Kent the width yields 17,17m, using the one from Renz' book it's 18,77.
CMU7842R is also pretty big (18cm in slant and 13,49cm wide) and would yield 16,9m and 18,48m respectively, depending on the formula.

That these two yield such different results is strange considering Jeremiah's root width method is supposed to work with all lamniforms. I could measure the perpendicular height but width is probably more reliable anyway, and usually the height method produces figures that are a bit lower than the width method so we know what to expect.

These are the figures for the rest of the teeth (ignoring the pathological specimen):
Height/width
6,004 4,291
6,004 4,527
6,004 4,645
6,004 4,763
6,004 4,803
6,024 4,33
6,024 4,72
6,024 4,842
6,063 4,212
6,063 4,645
6,063 4,645
6,063 4,685
6,063 4,685
6,062 4,921
6,102 4,212
6,102 4,724
6,122 4,252
6,141 4,33
6,181 4,094
6,181 4,685
6,259 4,881
mean(cm): 15,4283228571 11,5983657143(->14,547-15,89m TL)
max(cm):15,89786 12,49934 (->15,73-17,12m TL)
megmawlteeth.ods (13.57 KB)

Now these are not all in the same position but they all seem to be upper anterior or lateral specimens, so root width should work reasonably well with them, as those are the widest teeth of the dentition, and at least give us a good idea. Also it is of limited use for the size estimates of the whole species since its obviously an assimilation of big teeth for sale, not an unbiased sample, but it can tell us what ballpark we're in.

Strange enough several of the teeth above seem to be exactly the same slant height.

BTW someone with lots of spare time could try to derive a relationship between slant height and perpendicular height or width.

[Grey]

Nice effort. However I had told you Brett has not demonstrated any method, only showing the mean in a sample of white shark from Hubbell. The purpose of his scatterplot was to show the potential issues, not to establish a method of him. When speaking with him, he acknowledges the only available method based on width is the one by Jeremiah, that's the one he refers in his paper.

Wait for the details of Siversson's method based on total upper teeth width in the paper about Cardabiodon that we could apply to meg (I'd appreciate he briefly discusses meg size in it). I ignore the details, only knowing that he based it on a number of porbeagle, makos and white sharks specimen, species already with a respective size disparity and that the largest meg teeth predict an almost 20 m TL.

Another thing : web.archive.org/web/20080104173754/http://www.megmawl.com/define.html#lateral

Tooth Size:

One of the most frequent questions we receive is, "What size shark did my tooth come from?". Others are "Was my tooth from an adult or juvenile?" and "Was it from a male or female?". Another question to complicate the discussion would be "Where in the mouth did this tooth come from?". These are easy questions if we are talking about a 6 7/8 inch tooth. They are extremely hard questions to answer for many of the smaller teeth for these reasons:

We think that the megalodon evolved over a 20 million year period. At the end of this time, megalodon had evolved into the largest it had ever been. Then for whatever reason, the species became extinct. A 6 7/8 inch tooth would have come from one of these animals who lived about 2 million years ago. The shark would have been a mature female, 60 to 70 feet long and weighed 80,000 pounds. It most likely would have been an upper Anterior tooth.

Let's suppose that the species started out 22 million years ago as a descendant of Carcharocles chubutensis. Let's also suppose that a mature adult of that time reached a length of 25 feet. The largest tooth in her maw would only have been about 2 3/4 inches in slant height.

How do we describe the animal that a 3 inch tooth came from? Was it from a mature shark that lived 20 million years ago or a juvenile that lived 6 million years ago? Further complications come from changes due to ontogenetic stages in the development of an individual shark and species variation due to relative geographical isolation.

One of the ways we could be relatively comfortable with an intelligent speculation would be to date the strata that the tooth came from. Most of the river teeth and all of the teeth from "REFORMULATED" formations can not be dated in this manner because of the absence of "index fossils" or the mix of "INDEX" fossils that originated in the original layers that were "reformulated".


I don't know the scientific basis of this statement as I don't remember to have read, except in one occasion, that megalodon was that larger in the Pliocene than at its begining. I expect the first members of the species to be smaller of course, but not that smaller. I should discuss this with Kent and/or Siverson.

If this is true however, that even complicates the average size of 10-14 m that our fella coherentsheaf proposed, in that only teeth from the same age (and perhaps region) could be compared. And here again we have to problem of tooth position, life stage of the owner, adequate sizing method... We already struggle to know the maximum potential size of meg, and even then, trying to estimate an exact average range is almost impossible. Like in the near-totality of fossils species.

Also, that should please you theropod : web.archive.org/web/20070322071706/http://megmawl.com/measure.html

[Grey]

Dr. Mike Siversson mailed me a comparison of sizes between oceanic superpredators, only he asked me permission to put it on the forum (not that this minds him but he justifiably prefers to give formally his permission), I guess he has read some part of the forum (or carnivora). I will post after I get his approval (or those who are interested can see this with me privately).

[blaze]

It's been 20 days, you haven't got his approval yet? :sad face:

[Grey]

He's hard to contact directly these times but we can discuss it privately.

[blaze]

how?

[Grey]

I was recently discussing with a fossil collectore owning Mark Renz book, and he said me there is in it a naturel sized photo of Gordon Hubbell massive tooth specimen. Based on it, he measured the width of the tooth at 5.9 inches in width (14.98 cm). I was suspicious and directly asked to Renz but he just confirmed this : Yes, the tooth is 5.9 across the top of the base, but if you measure a little lower in the base, it's actually 6 inches.

So Gordon Hubbell tooth (found by Vito Bertucci) is really really huge and in all likelihood represents a predator of immense proportions.

[Grey]

coherentsheaf

I post here your response on another forum :

I dont count neonates and juveniles. The vast majority of sizable Megalodon teeth indicates below 14.5m individuals.

I dont count lateral/posterior teeth only anterior teeth. They easily make my case.

5 inchers probably belong to sharks around 12-13m long. So frequent five inchers dont make any case at all.

These observation are true for deposits were the majority of teeth come from sizable Megalodon, indicating that these were not waters for small fish. Still most Megalodon are far smaller than sizes commonly attributed to the species.

I believe to have aswered some of these points previously.Please do not simply restate them before addressing criticism.

You surprisingly forget or ignore some factors.

At first, may I recall you that nobody don't know for sure if a 5 incher corresponds to a shark of a given length ? As well as body size based on teeth length appears itself more doubtful than tooth width.

Then, why are you still considering that any isolated tooth comes from a full grown individual ? I mean, I don't learn to you that sharks loses THOUSANDS of teeth through their whole life. So just understand that a 5 incher just belongs to a shark that loses a tooth at one given moment of its life stage, nothing more.

This is even complicated by the potential sexual, regional, temporal sizes differences. Earlier teeth are not the same size as the later. Comparing 23 millions years and 5 millions years teeth to establish an average size makes no sense.


Consider a predatory tetrapod such as a 11 m Pliosaurus with 33 cm teeth, and consider that pliosaurs would lose and replace their teeth at the same speed and rythm than sharks through their whole life, you would expect to find uniquely 30 cm+ teeth ? Certainly not.

You say that megalodons were on average smaller than what is commonly stated. At first, a number of mentions only states 15 m as a typical size. Then, of course they talk of the potential full grown size of the species, in the absence of exact datas and absolute certainty of the relationship between teeth size and growth curve.


Also, I've seen that you compared megalodon to the basking shark on that forum. I know it's thanks to one information I've shared with you. Only, you have to know that consider the basking shark as an exact model for megalodon is absolutelu not certain either, according to Brett Kent :

Hard to say for sure, but I don't think meg and Cetorhinus centra are all that similar. The large meg vertebrae I've seen are pretty robust. They don't have the more tightly packed septa of the lamnids and odontaspids, but overall they're much more solidly built than those of Cetorhinus. The vertebrae of Cetorhinus are so poorly mineralized that they are almost always badly distorted during fossilization. It's very rare to see this type of distortion in meg vertebrae.

[theropod]

If one is talking about the average size of an extinct non-mammalian species, one never just refers to the mean of the size each individual potentially could have reached when maximum age was reached.
The fossil record, given appropriate assumptions are made for sampling, reflects the sizes usually seen in sexually mature individuals, that many may have grown bigger in their lifes is irrelevant since they also loose teeth in that case which will also be included in whatever analysis one does-they are just less common because sharks of such sizes are also fewer.

[Grey]

Any size statement always reflects the potential max size.

The blue whale is typically described as reaching 30 m, not 24 m, unless average is precised.
The white shark is typically described as reaching 6 m, not 4.5-5 m, unless they ask average size.

The same is done for extinct taxa in which we don't know the exact average sizes in most of the species.

But get lost theropod, I don't discuss with you genius, I was talking to another member.

[theropod]

Again, we know the maximum sizes even less, and numbers merely refer to the largest found specimens, which in most cases are closer to average sizes than anything else. Since you already made clear you won't accept the logic that different sample sizes will also cause the maxima of samples to be incomparable, why discuss this?

Blue whales are commonly cited to REACH 30m, great whites to occasionally exceed 6m. That's not the same as a general statement on the species' size, look at the wikipedia article. B. musculus is commonly said to be 100t, which is correct in that most specimens don't exceed that.

I see you now want to order me to keep quiet. Funny enough, when I tell you you should not respond to me if your response was going to be disrespectful, you ignore it too, so why do you think I'm not allowed to tell my opinion? It is simply that I agree with coherentsheaf, not you. What a disaster, because someone who disagrees with you is a fanboy...wait, only I am, regardless of what I write!

I must say it's quite ironic I'm less subject to defamations and arrogant insulting posts when I'm on Carnivora than when I'm here...

[coherentsheaf]

Sept 19, 2013 21:23:21 GMT 5 Grey said:

At first, may I recall you that nobody don't know for sure if a 5 incher corresponds to a shark of a given length ? As well as body size based on teeth length appears itself more doubtful than tooth width.

Sure we do not know how large these aimals are exactly but our point estimates are lower than commonly stated lengths.

Then, why are you still considering that any isolated tooth comes from a full grown individual ? I mean, I don't learn to you that sharks loses THOUSANDS of teeth through their whole life. So just understand that a 5 incher just belongs to a shark that loses a tooth at one given moment of its life stage, nothing more.

Because this is how the populations looked like. They were not all adults.

This is even complicated by the potential sexual, regional, temporal sizes differences. Earlier teeth are not the same size as the later. Comparing 23 millions years and 5 millions years teeth to establish an average size makes no sense.

Yeah early teeth are even smaller. E.g. the teeth in the Zurich museum are not much larger than gws teeth. Does not detract from the point.

Consider a predatory tetrapod such as a 11 m Pliosaurus with 33 cm teeth, and consider that pliosaurs would lose and replace their teeth at the same speed and rythm than sharks through their whole life, you would expect to find uniquely 30 cm+ teeth ? Certainly not.

Agreed, large individuals like Cumnor or MOA would be the exception. Most pliosaurs were smaller. Exactly as large Megalodon are the exception.

You say that megalodons were on average smaller than what is commonly stated. At first, a number of mentions only states 15 m as a typical size. Then, of course they talk of the potential full grown size of the species, in the absence of exact datas and absolute certainty of the relationship between teeth size and growth curve.

What I mean: If you were to swim in pliocene oceans and pop into Meg, it would likely be smaller than 15m, even if you swim offshore.

Also, I've seen that you compared megalodon to the basking shark on that forum. I know it's thanks to one information I've shared with you. Only, you have to know that consider the basking shark as an exact model for megalodon is absolutelu not certain either, according to Brett Kent :

Hard to say for sure, but I don't think meg and Cetorhinus centra are all that similar. The large meg vertebrae I've seen are pretty robust. They don't have the more tightly packed septa of the lamnids and odontaspids, but overall they're much more solidly built than those of Cetorhinus. The vertebrae of Cetorhinus are so poorly mineralized that they are almost always badly distorted during fossilization. It's very rare to see this type of distortion in meg vertebrae.

I think my comparison was inappropriate. Meg is not a basking shark. It is not a lamnid either.