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Post by theropod on Aug 5, 2018 14:51:23 GMT 5
Regarding the size of the owner of the 5.5m Nantucket Jawbone I used the average ratio between the two reported skull (cbl) and mandible lengths from James & Soundararajan to estimate the mandible lengths for Lambert et al.’s dataset of male sperm whales with known TL and CBL, then ran a linear regression (the residuals are not statistically significantly correlated with size, at R²=0.12 and p=0.27) of TL against mandible length. I’ve attached my data if someone wants to check my numbers. here is the resulting dataset: tl cbl jaw
1 1630 490 396.9964
2 1440 470 380.7925
3 1560 450 364.5886
4 1460 415 336.2317
5 1000 255 206.6002
6 1400 430 348.3846
7 1280 310 251.1610
8 1150 320 259.2630
9 1360 365 295.7218
10 1220 340 275.4669
11 810 213 169.0000
12 1740 445 368.0000
11 and 12 are the ones whose ratio between reported mandible and skull length was used. The ratios for the two specimens are within 5% of each other, the smaller specimen 79.3%, the larger 82.6%. If anyone has more data please let me know, but I think going by this ratio is a fairly reasonable prediction, since mandible size probably doesn’t deviate too much with regard to skull length. The 75% prediction interval would be 20.0-23.4m, for 50% it is 20.8-22.7m. So 21m is a bit on the conservative side, but over 25m is extremely unlikely. Considering this, I do think the 24m bull cited by McClain et al. is plausible though (at least it is within the 95% PI for the Nantucket jawbone. As for the supposed 26m whale that sank the Essex (Carrier et al. 2002), no solid material seems to exist backing that estimate at this point, although McClain does cite a jawbone at the BNHM supposedly indicating 25.6m (though not from a credible source…it would be interesting to know the measurements of that jaw). sam1 Theropod, I think the main factor here is the sample size. Two skulls are just not enough. The total proportional range in sperm whales is pretty big. The head length/total length proportions can go from 1:3 to 1:4, and the skull length/head length can vary significantly too, depending on the rostrum tissue(it tends to be bigger the bigger the animal is). A 5.5m jawbone means a head of around 7m length, so the possible TL could be 21-28m. But I won't hijack this thread any more. We can discuss the maximum possible size from a 5.5m mandible in a separate one. Condylobasal skull length does not include soft tissues, and the sample used for the head-body proportions is 12, not two. All clear now? Carrier, D. R., S. M. Deban, and J. Otterstrom. 2002: The face that sank the Essex: potential function of the spermaceti organ in aggression. Journal of Experimental Biology 205:1755–1763.
James, P., and R. Soundararajan. 1981: An osteological study on the sperm whale Physeter macrocephalus Linnaeus from Indian Ocean. Indian Journal of Fisheries 28:217–232.
Lambert, O., G. Bianucci, K. Post, C. de Muizon, R. Salas-Gismondi, M. Urbina, and J. Reumer. 2010: The giant bite of a new raptorial sperm whale from the Miocene epoch of Peru. Nature 466:105.
McClain, C. R., M. A. Balk, M. C. Benfield, T. A. Branch, C. Chen, J. Cosgrove, A. D. Dove, L. C. Gaskins, R. R. Helm, and F. G. Hochberg. 2015: Sizing ocean giants: patterns of intraspecific size variation in marine megafauna. PeerJ 3:e715.code: theworldofanimals.proboards.com/attachment/download/257
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Post by theropod on Aug 6, 2018 12:33:05 GMT 5
Grey : I have not seen Zenitani & Kato 2013, where do I find that paper? And how many specimens did they base that on? With the 12 data points that I have, I don’t so much "not take into account" non-linear scaling as simply find no solid evidence for it.  As you see, the residuals are pretty much randomly distributed. There is no statistically significant correlation between the two (as I wrote, p for that correlation is 0.27…), as you would expect to see if the scaling significantly deviated from linearity. So I don’t see any convincing evidence to reject the null-hypothesis of linearity for this size range. That is why I stuck with the linear model. Log-transforming it would simply not make a big difference anyway, but I would doubt the reliability of extrapolating such a model that far beyond the data range. That being said, the slope of the line is below isometry, there are several specimens in the dataset that when scaled isometrically would predict sizes well outside the 95% PI. So this does account for some degree of allometry, it’s just that the data for male Physeter that I have seem to scale linearly (as you can see for yourself).
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Post by sam1 on Aug 6, 2018 12:49:58 GMT 5
We are talking about the largest *possible* size here, not the *likely* size for a male with 5.5m mandible.
The 12 individual data sample is good enough to give a likely size, but it doesn't dismiss the possibily of an individual whale with a large rostrum protrusion, 7m head and a stretched HL:TL ratio (3.5-4).
The point is, it is very unlikely but still *possible* for a 5.5m jawbone to come from a 26m whale.
As for the mandible in question, it is claimed to come from a 24m animal.
And as for the Essex destroyer, the 26m figure was taken because that was the length of the Essex and sailors have claimed the whale was at least as long as the ship.
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Post by theropod on Aug 6, 2018 16:34:45 GMT 5
We are?
I’m not, I’m talking about an actual plausible size of the whale that bone came from, which I think would be 20-23m. That being said, the probability of that jawbone coming from a whale more than 25m long is less than 2.5%, based on these data, so that does amount to some quantification of "the largest possible size", even though that term is very vague. I think a good real-world definition for the "largest possible size" would be to take the upper end of the 95% confidence band. Which would be the 24.8m. A proportionately tiny head in a 20+m sperm whale simply isn’t that likely.
Of course the largest possible size in the strict sense is less constrained, it will just be astronomically unlikely. Could this be a 30m Physeter? Certainly in a few hundred thousand sperm whales there might be a few with proportions that could make this work. It’s just so far from the normal expected value that it’s pretty much meaningless. So I would argue that no, that is not a reasonable upper estimate for the specimen. Same problem as with Gottfried et al.’s 20.2m megalodon.
Interesting info regarding the Essex sperm whale.
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Post by Grey on Aug 6, 2018 18:15:55 GMT 5
And as for the Essex destroyer, the 26m figure was taken because that was the length of the Essex and sailors have claimed the whale was at least as long as the ship. Just like the fishermen who swear the great white they saw was 2 meters larger than their 21 foot boat. |
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Post by theropod on Aug 6, 2018 18:30:30 GMT 5
Does anybody know the measurement of the mandible McClain et al. mention, the one at the nhm? Is there any recorded jawbone larger than the 5.5m Nantucket specimen?
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Post by sam1 on Aug 6, 2018 19:46:45 GMT 5
Well, that was my intention. "But I won't hijack this thread any more. We can discuss the maximum possible size from a 5.5m mandible in a separate one" |
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Post by sam1 on Aug 6, 2018 19:50:01 GMT 5
And as for the Essex destroyer, the 26m figure was taken because that was the length of the Essex and sailors have claimed the whale was at least as long as the ship. Just like the fishermen who swear the great white they saw was 2 meters larger than their 21 foot boat. Except that the alleged shark is technically nothing more than a word of mouth while the whale in question actually sunk the ship. |
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Post by Grey on Aug 6, 2018 20:04:52 GMT 5
Just like the fishermen who swear the great white they saw was 2 meters larger than their 21 foot boat. Except that the alleged shark is technically nothing more than a word of mouth while the whale in question actually sunk the ship. The fact it sunk the ship doesn't make the claim more true from a scientifical standpoint. A sperm whale didn t need to be 85 feet to be able to destroy such a ship. |
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Post by sam1 on Aug 6, 2018 20:55:45 GMT 5
Except that the alleged shark is technically nothing more than a word of mouth while the whale in question actually sunk the ship. The fact it sunk the ship doesn't make the claim more true from a scientifical standpoint. A sperm whale didn t need to be 85 feet to be able to destroy such a ship. It doesn't make the figure true, but it adds a lot more weight to the whole picture. It's just not the same as some anecdotal testament, as you imply. Also keep in mind that the whale hit the ship twice.. after the first hit he floated in close proximity for a while, and then came back to finish the ship. |
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Post by theropod on Aug 6, 2018 21:12:55 GMT 5
In any case it was enough to be included in a peer-reviewed paper, that was my whole point, not that the figure was necessarily correct.
So the claim that such sizes are not being taken seriously by scientists is not true. The argument from authority regarding some popular scientific book not recognizing these sizes doesn’t work either, because we clearly have much more "authoritative" (i.e. peer-reviewed) sources (McClain et al. 2015, Carrier et al. 2002) that actually do recognize them.
That one bull isn’t an isolated ocurrence either, McClain et al. cited 8 other specimens between 21 and 23m long. Obviously this is an exceptional size for sperm whales to reach, but it would appear that it’s not completely anecdotal either. And coincidentally the probable size range of the Nantucket mandible fits this size range very nicely, so we do have physical evidence (at least given the length of that jaw is reported correctly) as well.
And yes, individual measurements by whalers can certainly be off, obviously. Still I find the error associated with these measurements quite acceptable compared to certain other size figures based on estimates, and even some measurements of extant animals such as great whites (Malta…) for that matter.
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Post by Grey on Aug 6, 2018 21:13:38 GMT 5
The fact it sunk the ship doesn't make the claim more true from a scientifical standpoint. A sperm whale didn t need to be 85 feet to be able to destroy such a ship. It doesn't make the figure true, but it adds a lot more weight to the whole picture. It's just not the same as some anecdotal testament, as you imply. Also keep in mind that the whale hit the ship twice.. after the first hit he floated in close proximity for a while, and then came back to finish the ship. Given the context and the shock, I would take such a statement with even more salt. The legendary GWS nicknamed submarine was witnessed several times in the 70's, including by a marine biologist, this doesn't make the claim of 8-9 m anymore true. A GWS was observed in the Dakar harbour by a marine biologist that was according to him 9 m (Maddalena 2001). The French paleontologist Jean-Loup Welcomme, who collects sharks teeth, told me the largest megalodon he has seen was in a Museum in Angers and was, in vertical height, 22 cm. George Blasing reported to have seen a broken tooth, the root only, the was twice larger than the same part in a 5 inches tooth he possessed. Despite these claims coming from scientists or educated people and being modern accounts, unlike those of the Essex which are 2 centuries old, we have to take these claims with extreme caution. |
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Post by Grey on Aug 6, 2018 21:22:42 GMT 5
In any case it was enough to be included in a peer-reviewed paper, that was my whole point, not that the figure was necessarily correct. So the claim that such sizes are not being taken seriously by scientists is not true. The argument from authority regarding some popular scientific book not recognizing these sizes doesn’t work either, because we clearly have much more "authoritative" (i.e. peer-reviewed) sources (McClain et al. 2015, Carrier et al. 2002) that actually do recognize them. That one bull isn’t an isolated ocurrence either, McClain et al. cited 8 other specimens between 21 and 23m long. Obviously this is an exceptional size for sperm whales to reach, but it would appear that it’s not completely anecdotal either. And coincidentally the probable size range of the Nantucket mandible fits this size range very nicely, so we do have physical evidence (at least given the length of that jaw is reported correctly) as well. And yes, individual measurements by whalers can certainly be off, obviously. Still I find the error associated with these measurements quite acceptable compared to certain other size figures based on estimates, and even some measurements of extant animals such as great whites (Malta…) for that matter. I have no issue with the data in McClain 2015. They are dealing with 8 specimens among 500 000 and appear solid enough. But they do not acknowledge any 26 m figure, unlike the Essex crew. I disagree with your comparison with Malta, there is enough scientific data from various sources indicating a size of 6.5-7 m for this individual. Arguing this case is less likely than a 200 years claim by whalers is certainly erroneous. Carrier 2002 only took the reported claim from the whalers, subsequent works bring doubts on this. |
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Post by theropod on Aug 6, 2018 21:38:32 GMT 5
True, they don’t acknowledge any such figure. Neither did I.
I think it’s rather clear I was not comparing "Malta" to the guesstimates for the Essex whale, but to actual measurements taken by whalers. It was you who reported that these measurements were frought with inaccuracy. However, the error doesn’t seem greater than in many figures you are yourself inclined to take seriously. If you acknowledge the sizes reported by McClain et al. then we are on the same page about that.
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Post by Grey on Aug 6, 2018 23:04:34 GMT 5
Yes, I slightly revised that statement of mine and accept them but have some issues about it :
- why Wood did not record them in his account.
- 100 years old whaling measurements are not the most reliable.
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Theropod, I think the main factor here is the sample size. Two skulls are just not enough.
