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Post by theropod on Feb 8, 2015 22:36:55 GMT 5
Well, that was my point.
Take a hypothetical specimen X% larger for one, and you have to do so with others too given that the situation is similar, which it is here. I don’t think we should adopt this practice, we should just compare the specimens to more typical ones of other species.
Btw you were talking about 25m earlier?
Fair enough. Still, it would be good to see an actual publication on the matter.
"There are several discrepancies between Romer and Lewis’ description and the
specimen as mounted. There are no records of modifications to the mount since it
was completed – thus, Romer and Lewis’ account seems simply to have contained a
number of errors, mainly concerning the position in the axial column of artificial
vertebrae that were included to mitigate what were believed to be gaps in the fossil as
collected. Romer and Lewis counted 46 preserved vertebrae – the mounted specimen
actually contains the remains of 45, including cervicals, pectorals, dorsals, sacrals, and
caudals. The posterior part of the tail is missing: the most posterior vertebrae in the
mount that contains fossil material is the ninth caudal, which is the 56th vertebrae
(v56) in the axial column of the mount. Forward of this point, 11 of the vertebrae in
the mount are entirely artificial.
[…]
The interpretation of MCZ1285 preferred here is ‘CRM 1’, with 13 cervicals, 3
pectorals, and 19 dorsals. This interpretation depends upon one of the restored
cervical vertebrae as being unwarranted: circumstantial support for this comes from
comparison with USNM 4989, where the proximal end of the rib on v12 indicates is
of similar appearance and relative size in its proximal portion to that preserved on
v13 of the MCZ 1285 mount: v14 of the MCZ1285 mount would thus, by analogy
with USNM 4989, be a prothoracico-cervical, equivalent to v13 in USNM 4989,
leaving v14-v16 as the pectoral vertebrae. The accuracy (or not) of this interpretation
will be more certain once the pectoral vertebrae in other specimens of
brachaucheniid – in particular, USNM 4989, QM F10113, RMFM R236 (see below),
and the K. boyacensis holotype – have been described more fully, and at that point it
would be worth re-visiting the anatomy of the pectoral region in MCZ 1285.
Table 6-13:
Interp. head neck torso snout-hip tail TL volume(litres) femur length
Mount 2,231 1,989 4,285 8,506 3,904 12,409 17,888 1,060
CRM 1 2,287 1,870 3,156 7,312 3,356 10,668 11,366 960
CRM 2 2,256 1,751 3,156 7,163 3,288 10,451 10,684 -
CRM 3 2,308 1,870 3,291 7,469 3,428 10,897 12,113 -
[…]
An uncritical acceptance of the mounted specimen gives a total length (TL) of 12.4
metres (compare with Romer & Lewis’ reconstructed length of 12.8 metres, which
appears to include a proportionally longer tail), and a volume of 17.9 m3 (equating to
17.9 tonnes if a density of 1,000 kg/m3 is assumed). In contrast, the most generous
of the revised interpretations (CRM 3) gives a TL of 10.9 metres and a volume of
12.1 m3, whilst the most conservative (CRM 2) gives a TL of 12.5 metres and a
volume of 10.6 m3. Although not as large as initially reconstructed, MCZ1285
nevertheless represents a large individual, with a TL of 10.5–10.9 metres and a body
mass of 10.6–12.1 tonnes."
from McHenry 2009: pp. 397f.
This is what McHenry wrote on the earlier paper on the peterborough vertebra:
McHenry et al. 19961 reidentified an isolated vertebra (PETMG R272 – previously
identified as from a sauropod dinosaur) from the Oxford Clay near Peterborough as
a pliosaur cervical vertebra: by comparison with the Harvard Kronosaurus mount, they
estimated the length at between 15-18 m. However, the assumption of accuracy in
the Harvard mount (see below), and the identity of the Peterborough vertebra, have
been questioned (A. Cruickshank, pers. comm.): the vertebra may well belong to a
sauropod after all, although consensus has not been reached on this matter (D.
Naish, pers. comm.).
This seems compelling to me, or was he misinformed about the number of hypothesized vertebrae in the mount?
Thanks, you’re right. That sounds like an interesting subject for someone to publish a paper or thesis on, I hope it happens soon…
That’s because the data for the saltwater crocodile were based on in vivo measurements, the shark’s bite force was a computer simulation. At least in reptiles, the latter are known to produce significant underestimates, but how much can’t be ascertained, neither how much this applies to the shark. Unfortunately this is not an apples to apples comparison. Estimations for Pliosaurs and crocodilians of similar skull lenght appear to be similar when they base on a comparable method (Foffa et al. 2014).
I think we can be reasonably confident that a pliosaur has a higher bite force than a shark at equal body mass, but how much exactly is not clear.
Foffa et al. provided some discussion of how pliosaurs compare to crocodilians:
"This mismatch between in vivo and digitally calculated
bite forces can be explained in various ways:
1 Crocodilians generate higher bite forces at similar
sizes.
2 Erickson et al. (2012) recorded the highest values, pre-
sumably produced during impact peaks; in this regard,
it was noticed that sustained bites are considerably
lower than static values (see also Bates & Falkingham,
2012; Fig. 2) and our models better represent static con-
ditions. If confirmed, this would mean that the values
are representative of different situations, and so cau-
tion is recommended when comparing them; it would
also explain why other digitally calculated values (Kron-
osaurus, Crocodylus and Alligator) (McHenry, 2009;
Bates & Falkingham, 2012) are comparable with our
rescaled model and much lower than Erickson’s values.
3 Our correction for pennation is not enough. It might
be that crocodilians have more pennate muscles than
pliosaurs do, or vice versa.
4 As previously discussed, M. pt (ventralis) is uncon-
strained by the lower jaw bones in most lepidosaurs,
birds and crocodiles; the extent of this muscle cannot
be ascertained for the pliosaur. Hence our model and
correction for M. pt muscle might still underestimate
its volume (see Data S1,b)."
Bold part highlighted by myself.
He made a conversion error with that figure. I seem to recall he stated something about the skull being restored too shallow somewhere.
Yes, that is intriguing. Qualitative features suggest immense, perhaps unparalelled bite strenght. Estimates from quantitative studies are very high, but comparable to those of other very powerful biters. I think the key is simply size, in a hypothetical 18-20m pliosaur the jaw muscles would simply be ridiculously gigantic, while P. kevani, albeit very large, doesn’t have a significantly larger skull than other giant predators, or for that matter the oversized Deinosuchus skull Foffa et al. compared it to.
The current estimates suggest pliosaurs were similarly powerful to crocodiles at equivalent skull sizes, but obviously they had proportionately larger skulls and were larger overall. But the dry skull method apparently underestimates bite force more so than multibody dynamics (e.g. Bates & Falkingham 2012 in Foffa et al. 2014, Table 3), and in vivo measurements may overestimate it for our purposes because they record the bite force peaks and not sustained bite forces.
–––References:
Foffa, Davide; Cuff, Andrew R.; Sassoon, Judyth; Rayfield, Emily J.; Mavrogordato, Mark N.; Benton, Michael J.: Functional anatomy and feeding biomechanics of a giant Upper Jurassic pliosaur (Reptilia: Sauropterygia) from Weymouth Bay, Dorset, UK. Journal of Anatomy, Vol. 225 (2014); 2; pp. 209-219
McHenry, Colin R.: 'Devourer of Gods'. The palaeoecology of the
Cretaceous pliosaur Kronosaurus queenslandicus. Newcastle (2009)
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blaze
Paleo-artist 
Posts: 766
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Post by blaze on Feb 9, 2015 0:06:50 GMT 5
The Tubigen specimen.... I've realized something, Check Noé et al (2003), remember the 4.88m Liopleurodon mentioned in that publication? GPIT 1754/2, GPIT is the institutional abbreviation for Institut und Museum für Geologie und Pal¨aontologie, Tübingen, so unless this museum has two complete/subcomplete Liopleurodon specimens, this is the supposedly uncatalogued 5.3m specimen mentioned by Buchy et al.
Applying this correction to the Peterborough vertebra estimate results in 17.6m. Of course, Assuming no allometric growth of any kind.
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Post by Grey on Feb 9, 2015 0:10:08 GMT 5
The Tubigen specimen.... I've realized something, Check Noé et al (2003), remember the 4.88m Liopleurodon mentioned in that publication? GPIT 1754/2, GPIT is the institutional abbreviation for Institut und Museum für Geologie und Pal¨aontologie, Tübingen, so unless this museum has two complete/subcomplete Liopleurodon specimens, this is the supposedly uncatalogued 5.3m specimen mentioned by Buchy et al. Applying this correction to the Peterborough vertebra estimate results in 17.6m. Of course, Assuming no allometric growth of any kind. Indeed I have seen it. Maybe the 5.3 m figure is the estimate of the pliosaur as complete, since the skeleton is said to be subcomplete. |
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Post by creature386 on Feb 9, 2015 0:10:50 GMT 5
Is that from you Macronectes? Did you delete your comment or is my computer for some reason not showing it (sorry if the question sounds stupid)?
EDIT: Forget it, it sounded like a reaction to what I wrote.
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Post by theropod on Feb 9, 2015 0:39:09 GMT 5
The Tubigen specimen.... I've realized something, Check Noé et al (2003), remember the 4.88m Liopleurodon mentioned in that publication? GPIT 1754/2, GPIT is the institutional abbreviation for Institut und Museum für Geologie und Paläontologie, Tübingen, so unless this museum has two complete/subcomplete Liopleurodon specimens, this is the supposedly uncatalogued 5.3m specimen mentioned by Buchy et al. Applying this correction to the Peterborough vertebra estimate results in 17.6m. Of course, Assuming no allometric growth of any kind. I think that was what I had in mind. eprints.gla.ac.uk/55067/1/55067.pdfBuchy et al. cite an unpublished doctoral thesis for the specimen (Noé 2001). The size of the cranium from which CAMSM J.27424
was derived can be estimated by comparison with
NHM R2680. The isolated cranium of NHM R2680
has a snout to occipital condyle length of 1120 mm
(Andrews, 1913, p. 21) and a paroccipital length of
150 mm (Andrews, 1897, p. 178). CAMSM J.27424
has a paroccipital process length of 165 mm. Assuming
a 1:1growthratiobetweenthecraniumandparoccipital
process beyond the 1.12 m cranial length of NHM
R2680, the length of skull from which CAMSM J.27424 came can be estimated at approximately
1.23 m. This length estimate is slightly shorter than an
‘old adult’ (sensu Brown, 1981) individual of
Liopleurodon ferox (NHM R3536), estimated at 1265 mm from
snout tip to occipital condyle (Andrews, 1913, p. 22).
The overall length of the animal from which
CAMSM J.27424 came can be estimated by comparison to a skeleton of
Liopleurodon ferox (GPIT1754/2).
GPIT 1754/2 has a skull:total body length ratio of
approximately 1:5.19 (skull length 0.94m,overall body
length including skull 4.88 m). This would indicate a
calculated overall body length for the CAMSM J.27424
animal of approximately 6.39 metres.
Noé et al. 2003 Looks as if it was the complete lenght. This indicates a skull 19.3% of total lenght. So given that Buchy’s vertebral measurement for it and McHenry’s for the Peterborough vertebra are correct, the figures are as follows: dorsal vertebral width 252.5÷70×488=17.6m 252.5÷70×488=17.6m And while we are at it, for the MoA: dorsal vertebral width 200÷70×488=13.9m femoral head lenght 450÷140×488=15.7m creature386: theworldofanimals.proboards.com/post/21266/thread |
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Post by Grey on Feb 9, 2015 1:32:16 GMT 5
I note that the old Westbury pliosaur has fused sutures. This makes me wonder further if the Aramberri pliosaur with its unfused sutures is really a full grown adult.
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Post by theropod on Feb 9, 2015 2:29:49 GMT 5
It probably is not full grown, as it likely didn’t have determinate growth (unfused sutures representing growth zones). The more relevant questions would be whether it was still in an exponential stage of growth when it died, or whether it was socially or ecologically mature and could thus be considered an adult (adult in the same sense that is used in theropods). It depends on that into which part of the size distribution it is likely to fall.
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Post by Grey on Feb 9, 2015 2:44:46 GMT 5
Yeah. But we just don't know the statistical size distribution in pliosaurs, even less in that undescribed species so it's anyone guess.
My guess is that, based on the Peterborough specimens (see below), if 20 m is a normal adult size for some giants pliosaurs, then the full grown size of the MoA could maybe have been +18-20 m.
I ll ask to Noé if his estimate based on the Tubingen skeleton at 1.5,19 isn't off given that :
- Buchy reports the skeleton as subcomplete
- Noe repeated me that we must use 1.6 rather than 1.5 or 1.4 for Jurassic pliosaurs.
If the Tubingen Liopleurodon is really subcomplete and applying the 1.6 ratio this gives :
- a 5.64 m complete skeleton
- the MoA at 17.7-18.1 m based on respectively vertebra and femoral head measurement.
- the Peterborough at 20.3 m.
I need to ask him.
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Post by theropod on Feb 9, 2015 3:58:50 GMT 5
Yeah. But we just don't know the statistical size distribution in pliosaurs, even less in that undescribed species so it's anyone guess. That’s true. We don’t know it either way. But what its state of maturity would tell us is whether we should assume it’s a typical adult, or smaller than the typical adult. A fully grown or de facto fully grown adult on the other hand is probably a very rare ocurrence (at least it is in other large reptilian predators), and larger than the average mature individual. My guess is that, based on the Peterborough specimens (see below), if 20 m is a normal adult size for some giants pliosaurs, then the full grown size of the MoA could maybe have been +18-20 m. I ll ask to Noé if his estimate based on the Tubingen skeleton at 1.5,19 isn't off given that : - Buchy reports the skeleton as subcomplete - Noe repeated me that we must use 1.6 rather than 1.5 or 1.4 for Jurassic pliosaurs. If the Tubingen Liopleurodon is really subcomplete and applying the 1.6 ratio this gives : - a 5.64 m complete skeleton - the MoA at 17.7-18.1 m based on respectively vertebra and femoral head measurement. - the Peterborough at 20.3 m. I need to ask him. That’s a good idea. This makes me sceptical tough. Buchy repeatedly published estimates of about 15m, 18m wasn’t ever scientifically estimated anywhere (didn’t she even criticise it somewhere?). The most recent estimates by Frey & Stinnesbeck were 14m or less based on the vertebrae. I tend to think it’s the 1:6 ratio that is too generous, especially considering the fairly detailed figures reported by Noé for that Liopleurodon.  This is in all probability the Liopleurodon in question. I’ll see whether I can make a trip to Tübingen or at least pop in while passing this summer. |
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Post by Grey on Feb 9, 2015 5:29:30 GMT 5
In fact Buchy estimates were precisely "at least 15 m". Sounds like a rounded figure.
I don't know if 1.6 is too much but that's what Noé repeatedly said me to use with Jurassic pliosaurs.
If we're looking at 1.6 ratio, the Peterborough pliosaur could indeed be gigantic. The Tübingen specimen has a 94 cm skull and 70 mm thoracic vertebra. Applied to Peterborough this yeilds a 3.38 m skull. Using the 1.6 ratio proposed by Noé this yeilds a 20.3 m figure. And I dont know the size of the other vertebra. I had read somewhere both were about 40-50 % larger than Kronosaurus comparable material. Not sure at all but this could mean the other to be 260-270 mm wide.
Regarding the unfused sutures, you then agree that this represents not fully grown individuals ?
I think Frey et al. referal was based on McHenry estimate though in another part of the book they still list the specimen at around 15 m.
I had contacted Dino in 2011, he said the specimen was in the 14-18 m range, likely late juvenile/subadult.
As an example, I know that Cryptoclidus is known from only 3-4 m immature individuals because of unfused sutures, the 6-8 m estimates being extrapolated for the adults.
I would ask this from another angle as well :
- do we know any other macropredator around 15 m that still exhibits immature features ?
And if this is pedomorphy, why this would have occured only in pliosaurs and not in others giants aquatic tetrapods (cetaceans, ichthyosaurs, mosasaurs, giants crocodilians).
Regarding the 25 m figure we were talking earlier, I was only reporting this from Martill to show that this is only hypothetical, not necessarilly an exageration. The point being is that we have possibly a unique pliosaur individual in the 20 m mark, whereas such a size is only encountered in remarkably sperm whales. That could (I mean could) mean that 24 m is not an absurd exageration (it is certainly when we bases it on the available substantially preserved Liopleurodon skeletons) but something hypothetically possible, like a 14.5-15 m theropod individual which might have existed.
Yes this is the Tübingen Liopleurodon. Note the tail which seems quite uncomplete.
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blaze
Paleo-artist
Posts: 766
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Post by blaze on Feb 9, 2015 7:47:04 GMT 5
We are looking at it from an angle and there doesn't seem to be photos taken from the side anywhere on the internet, the tail doesn't seem incomplete to me but who knows, Buchy calling it subcomplete is not necesarly a reference of "it's missing several vertebrae", it could be limbs, ribs or parts of the pectoral, shoulder girdle.
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Post by Grey on Feb 9, 2015 8:31:36 GMT 5
Are you sure blaze ?
All the pictures I see depict a rather extremely short tail.
And there is this ratio suggested by Noé of being 1.6 rather than 1.5.
I assume that Buchy's precision of it being subcomplete is related to the length since she precised this in the contexte of estimating the size of the Aramberri pliosaur.
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Post by theropod on Feb 9, 2015 16:30:50 GMT 5
In fact Buchy estimates were precisely "at least 15 m". Sounds like a rounded figure. And it is, but not down from 18m. But the only thing he published is quite different, so that’s very peculiar. I do. The range is decidedly higher than McHenry’s estimates for the same specimen. In fact, it fits what you get from using the Tübingen Liopleurodon’s measurements as reported by Noé 2003 (the estimates were based on vertebral width, which was 20cm, 2.86 times the size of that Liopleurodon, which would indicate a lenght approaching 14m). I think they may have taken it into account, but also used other specimens for comparison. The book we are talking about is from 2014 and estimated it at 12-14m. Was there a quantitative method used to arrive at that figure? If not, that isn’t an extrapolation, just a guess. There are certainly sperm whales, and thus definitely also megalodons that size that were still growing. Perhaps not that much tough, that’s why it’s important to know the specifics of whether this is normal for an adult, but still in a phase of substantial growth, or whether it’s subadult. If we can trust the asessment of it being a subadult, then it’s probably a small specimen. I think the problem is that scientists arguing either of these points have not actually confronted each other’s arguments. |
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Post by Grey on Feb 9, 2015 18:30:00 GMT 5
Hmm depends. The Tübingen skull is 94 cm. Using the 1.6 ratio this yeilds a TL of 5.6 m for the complete skeleton. Using the femoral head comparison you exacly get 18 m for Aramberri. Using the 5.3 m figure provided by Buchy, you get 17 m. That's why I need to ask him, but the fact he repeated me to use that, and that others others authors (Naish) propose this as well, makes me think the 1/5.19 ratio is outdated. I think you're wrong here. Using the 4.88 m figure for the Tübingen skeleton, you get 13.94 m (from vertebral measurement) and 15.68 m (from femoral). That's definitely larger than 12-14 m. And again : the 4.88 m figure most likely isn't the complete one and that most adequate ratio we have to use a 1.6. I don't know what is the basis for Frey 2014 estimate and I really think it is based on Kronosaurus rather than Liopleurodon. The issue with the Aramberri pliosaur size is whetever Liopleurodon or Kronosaurus is the best analogue to use. I know man, remember it's me who reported the book. I just posted the 2011 information by Frey for principle. I don't know, that's from Naish interview : "There is some confusion about the total length of Cryptoclidus. All of the good specimens indicate total lengths of 3-4 m but several authors have said that these are juveniles or subadults, and that the true adult length was more like 6-8 m." blogs.scientificamerican.com/tetrapod-zoology/2014/03/03/plesiosaur-peril-and-plesiosaur-lifestyle-and-behaviour/Just a thought, according to the 2015 paper about oceans giants, 95 % of the sperm whales ever recorded have been under 15 m. Following Gottfried and Pimiento data, a Meg reached adulthood in the 10-14 m range. This pliosaur would be possibly at least 15 m (using Liopleurodon based estimates) and is stated as possibly juvenile/subadult. And that's just one specimen of a likely new taxon. To me, this could put the specimen potentially above sperm whales and megs. Again I mean "could". If I'm right, the Aramberri pliosaur and the Peterborough vertebra (as maybe some others undescribed remains) are hinting on the existence of really massive pliosaurs in the Upper Jurassic. |
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Post by theropod on Feb 9, 2015 18:56:50 GMT 5
Hmm depends. The Tübingen skull is 94 cm. Using the 1.6 ratio this yeilds a TL of 5.6 m for the complete skeleton. Using the femoral head comparison you exacly get 18 m for Aramberri. Using the 5.3 m figure provided by Buchy, you get 17 m. And yet, what she wrote was 15m, I think if the actual figure she arrived at had been 20% higher that would have been accounted for. And she lowered the figure for the Liopleurodon to 5m in her thesis. Maybe that was a correction due to reading Noé et al. 2003? Naish used 17% head lenght, that’s between both. These are McHenry’s estimates for the Aramberri specimen based on brachaucheniids: snout-hip TL volume
min 4,963 7,240 3,553
mean 6,674 9,737 8,642
mean(by width) 8,016 11,696 14,976
max 8,502 12,404 17,865 Table 5-20 C, p. 417 That’s what I was referring to. The estimates in question were only based on the vertebrae, not the femoral head. The specimen was supposed to be more similar to Kronosaurus than other contemporary pliosaurs are, so I think both have their value. But only application of more detailed morphometrics will tell us more. that does sound like a guess. And the average lenght for fully grown bulls is almost 16m, while 13-15m bulls are usually still growing (see page 30 here→), so there’s a difference between fully grown individuals and the bulk of the population, not just in pliosaurs, but in most animals. Adult ≠ fully grown, look at growth curves for these animals. Mature individuals do grow, even in sperm whales, and of course in sharks and reptiles. Of course it could, I just wouldn’t be too sure of that with so little to work with. This "possibly" itself bases on an uncertain length figure for an undescribed subadult Liopleurodon. This is certainly an intriguing possibility, but it would hold a lot more credibility if the data it is based on were not ambiguous. |
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