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Post by Grey on Feb 9, 2015 19:15:59 GMT 5
"At least 15 m", that's a difference. I think Buchy (for having speak with her) was just rather conservative. But the calculation is here.
Even using the, for some reasons, lowered 5 m figure for the Tübingen Liopleurodon you get 16 m.
17 % is almost 1/5.9
Definitely nearer to 1.6 than 1.5,19
Yes, I've edited my post, I had confused for the Peterborough estimate in his thesis.
Yet, you see that using the lowest size figure for the Tübingen specimen from vertebral measurement, you get 14 m.
I think that sizes estimates of 12 m for the Aramberri pliosaur can only be based from Kronosaurus, not Liopleurodon.
Yes, the acount says a kronosaurid affinity, but it does not refer to it as a true kronosaurid yet. I hope there's enough material to allow morphometrics scrutinity.
Good guess since this is widely in acceptance the adult size for Cryptoclidus. Checing the papers would be useful.
The point is the Aramberri is possibly at least 15 m and a late juvenile/subadult. I don't think this is something seen in Physeter, let alone Carcharocles.
Certainly, although I don't think determine the actual status of the Tübingen Liopleurodon will be difficult to solve.
The main issue I guess is whetever using Kronosaurus is valid. As much as I think using it for Peterborough is most likely inaccurate, I'm not sure for Aramberri.
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Post by theropod on Feb 9, 2015 19:28:13 GMT 5
I realize that, that’s why it would make most sense if the 5m were rounded up.
That’s why it would fit; close to 14m based on that specimen, close to 12m based on brachaucheniids.
If it’s some sort of transitional form intermediate between two shapes, we should take into account both types it is bracketed by.
That’s the guess being cited in the absence of better data then, nothing more. I’ll check the papers.
That’s the question, isn’t it? Is it an adult that retained unusual paedomorphics (although in any case probably still growing, unless its growth profile was extremely unusual), or is it a true subadult or juvenile?
As I wrote, I think using Kronosaurus for the peterborough vertebra is about as reliable as using Physeter for Livyatan.
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Post by Grey on Feb 9, 2015 19:49:07 GMT 5
My point is that I suspect 5 m for the Tübingen Liopleurodon is undersize. So 14 m would be conservative for Aramberri. I'll ask Noé...
As ever, let's await for more information. I'd say that for now we can use both.
But my point is that if we use Liopleurodon, we can get figures significantly above 15 m.
Yes, but it's quite interesting to see that no one has ever complained about this so far. A number of specimens have been known from only juveniles, with the adult size being guessed afterward.
That's the question.
I know that the Westbury pliosaur is an old individual and has fused cranial sutures. So some large pliosaurs achieved their life with fused sutures (at least in the skull).
About the pedomorphy suggested by Buchy in her thesis, I question why it would occured only in giants pliosaurs and not in others large marine tetrapods such as ichthyosaurs, mosasaurs and cetaceans.
Yes I had realized this analogy. Damn, if Liopleurodon is accurate, this pliosaur could have been really gigantic.
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Post by Grey on Feb 9, 2015 20:37:00 GMT 5
I've just asked to a contact who observed the Tübingen skeleton, he confirmed it is definitely uncomplete, especially in the tail region.  |
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Post by theropod on Feb 9, 2015 23:19:44 GMT 5
^Those are clearly far too few caudal vertebrae, even tough they seem to articulate nicely. Andrews (1913) states there were about 25-30 in Pliosaurus (=Liopleurodon) ferox and about 30 in Simolestes vorax.
Btw these could be helpful:
Length from tip of snout to occipital condyle 112.0
,, „ „ anterior angle of external nares 57.0
„ ,, „ ,, „ internal nares 36.0
Length from tip of snout to posterior end of the facial
processes of the premaxilla 74.0
Length of the external nares 5.0
„ „ internal nares 6.5
,, posterior interpterygoid vacuities 11.O
Width of skull between the outer angles of the quadrates
(perhaps exaggerated by crushing) 50.0
Width of skull at level of transpalatine hone 48.0
„ ,, middle of internal nares 19.0
,, „ at diastema 11.3
„ „ at widest part of premaxilla? 12.
Width of articular surface of quadrate 12.6
Greatest (transverse) diameter of occipital condyle .... 6.5
Teeth (PL II. figs. 2, 2 a, 2 b, 3, 4, 4 a): Largest Smallest
Length along outside of curve 23.5 6.2
Length of crown 8.5 2.0
Diameter at base of crown 2.8 1.1
Skull : length from quadrate to tip of snout 154.0
„ „ occipital condyle to tip of snout 126.5
transverse diameter of occipital condyle 8.0
width between outer ends of quadrates 72.0
width of quadrate 15.0
width of snout at constriction 13.7
,, ,, widest par of anterior expansion 15.4
Mandible : extreme length 154.0
length of symphysis 30.5
width just behind symphysis 17.0
„ of articular surface 16.7
length of postarticular process 10.5
Teeth
Length along middle of curve .... 19.0 .. 7.8
Height of crown 7.5 7.0 2.5
Greatest diameter of base of crown 3.0 2.7 1.5
Vertebra Atlas and axis. 4th (cervical) 15th(cervical) 17th(cervical) 23rd(pectoral) Anterior caudals
Length of centrum on mid-ventral line . 5.6 4.9 4.3 5.0 5.1 6.0 4.5
Width of posterior face of . . centrum 10.0 12.0 11.5 12.8 12.5 10.5 10.0
Height of posterior face of . . centrum 8.9 10.4 10.6 11.0 11.5 8.6 9.1
„ to top of neural spine .. 30.9 32.9 33.0
..„ of neural arch .. 22.2 21.7
of neural spine .. .. 17.3 17.0
Andrews 1913: pp. 21f.
This is just a roughly corrected OCR result, so if something doesn’t make sense, consult the paper. But a few things of notice:
• Mandibular and Premaxilla-quadrate lenght are both about 22% larger than condylobasal skull lenght.
• Condylobasal lenght is 10.12 times the width of an anterior dorsal. The Tübingen Liopleurodon seems to have a proportionately longer skull (94/7=13.43). Maybe Noé’s measurement is maximum skull lenght: In that case, condylobasal lenght would be about 77cm, which would bring the ratio down to 11.03. Still, it either has a proportionately longer skull, proportionately narrower centra, or a combination of both.
• Teeth seem highly variable, I’m starting to question whether we should really use them, especially with such limited samples to quentify their variations. In this case for example, the smaller skull has considerably bigger teeth. Also, the question is how comparative values were measured? Along the curve or in straight line?
–––Reference:
Andrews, Charles W.: A descriptive Catalogue of the marine Reptiles of the Oxford Clay. Based on the Leeds Collection in the British Museum (Natural History), London. Part II. London (1913)
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Post by theropod on Feb 9, 2015 23:39:53 GMT 5
I guess we’ll see then. We can, I’m not arguing against that. It’s just not a certainty, and it depends heavily on what is as of now an ambiguity of the data. The amount of complaints about speculative methods of size estimates in extinct animals scales like this, where y is the complaining index and x is the estimated total lenght of the taxon in question: y=-50+1.5xOf course there is bound to be significant variation tough, and this simple correlation fails to account for other factors, such as the number of works dealing with it, but as a mean estimate we could assume that there will not be complaints about this in an animal the size of Cryptoclidus.  Where was this reported btw? These are probably the pliosaur equivalent of FMNH PR 2081. Exceptionally old and mature individuals that had reached a phase of neglegible growth. Are there any data on bone histology (LAGs, presence of an External fundamental system etc.)? That’s a good question, but it could be explained by different growth models (cetaceans have determinate growth) or examination bias (giant ichthyosaurs are very poorly studied and fragmentary). Also, Pliosaurs have a very different mode of locomotion from all these animals, which may require different adaptions of the skeletal system (although I’m unable to come up with a concrete reason why they would benefit from unfused sutures). But what this definitely doesn’t explain is why there are large pliosaurs that show signs of osteological maturity. If there are large pliosaur specimens actually showing signs of osteological maturity, that seems more in favour of it being more parsimonous that this was normal for them, but that most specimens that we have were simply relatively immature. As I’ve mentioned earlier, there are cases were a substantial portion of a population (or even all of them) are immature. For example, based on femur lenghts, 82% of all Allosaurus individuals in Cleveland Lloyd are juveniles and subadults (Gates 2005), and it appears that there is a substantial bias towards immature theropods in the Solnhofen Formation (see this→ and this→ thread). We should compare the present evidence. "However, the neurocentral sutures remain unfused in very large
thalassophonean individuals, including Late Jurassic specimens
such as CAMSM J.35990 [57], the holotype of Pliosaurus carpenteri
(pers. obs. of BRSMG Cd6172) and the large Mexican specimen
[2]. Thus, it is possible that vertebral sutural fusion was extremely
delayed or never occurred in thalassophoneans. If so, vertebral
sutural fusion cannot be used as a reliable indicator of ontogenetic
stage in Thalassophonea (contra [2])."Benson et al. 2013"However reliable this character may be in other
groups of reptiles, its validity as an indicator of ontogenetic stage in pliosaurids and
The palaeoecology of the Cretaceous pliosaur Kronosaurus queenslandicus
brachaucheniids is doubtful. Very few pliosaurid and no brachaucheniid vertebrae
have the neural arches fused to the centra (pers. obs.); unless all of the large
Kronosaurus specimens are interpreted as juveniles, it appears that this particular
feature is paedamorphic in large pliosaurs and that claims that the Aramberri
specimen is a juvenile are misplaced."McHenry 2009: pp. 432f."Thus UANL-FCT-R2 represents the most complete very large pliosaur known to date, and
additionally exhibits an immature osteological condition, raising the question of the size, a fully
ossified member of the same taxon could have reached. It was shown that forms with unfused
neural arches represent juveniles in small (some meters long) plesiosaurian taxa (Brown, 1981).
Fusion of the neural arch to the vertebral body may have occurred earlier in life in pliosaurs than
in crocodiles (Buchy et al., 2006d); the growth rate of crocodiles most likely cannot be used to
estimate growth rate in pliosaurs. Crocodiles are small when they hatch because they have to
develop within the restricted space of an egg; on the contrary it was argued that pliosaurs were
ovoviviparous (Cheng et al., 2004; Buchy et al., 2005a). Thus newborns could be larger compared
to adults than are hatchling crocodiles, and the growth rate during the first months or years were
not necessarily similar. Another aspect is sexual maturity, which might have occurred before
osteological maturity, a phenomenon that is quite common, and possibly advantageous in
evolutionary terms (e.g. Gould, 1977; McKinney, 1988): the parents of UANL-FCT-R2 were not
necessarily much larger than it was when it died. Other far (but possibly closer) relatives are
lizards. Recent forms, however, differ from pliosaurs in many aspects, such as size, anatomy,
mode of life, etc., so that they cannot represent a reliable model for pliosaurs (see Buchy et al.,
2005a). Moreover, osteological maturity might never have been reached in very large pliosaurs, a
partly cartilaginous skeleton being then no sign of young individual age: adult giant pliosaurs
might have retained juvenile features including non-fusion of the bones (contra Buchy et al.,
2006d) as a consequence of e.g. enormous metabolic requirements or to save weight. Cartilage
might have played an essential role in their biomechanics. It is usually argued that cartilage is less
solid than bone, less resistant against the tensions created by muscles and movement; though, it is
also better absorbing shocks and loads (e.g. Evans, 2005 and references therein). Another, indirect
argument in favour of preservation in adult giant pliosaurs of a partly cartilaginous skeleton is the
rarity of such remains in the fossil record, when marine environments offer better opportunities
for fossilisation than continental ones and remains of sauropods as large as or larger than UANL-
FCT-R2 are relatively common. Giant pliosaurs must have been rare in Late Jurassic ecosystems,
as are normally large carnivores as compared to herbivores; during geological time it must still
have represented series of populations comprising a sufficient number of individuals to breed. A
partly cartilaginous skeleton would help explain why so few among these were fossilised or had
their remains correctly identified."Buchy 2007: pp. 29f.I think we did go through all of that before, when things seemed in favour of what Buchy argues in the above quote, but I seem to recall there were other examples. The difference is that based on current data it seems less of a stretch that their fossil record could actually be that biased towards immature specimens. –––References: Benson, Roger B. J.; Evans, Mark; Smith, Adam S.; Sassoon, Judyth; Moore-Faye, Scott; Ketchum, Hilary F.; Forrest, Richard: A Giant Pliosaurid Skull from the Late Jurassic of England. PLoS ONE, Vol. 8 (2013); 5; pp. 1-34 Buchy, Marie-Céline: Mesozoic marine reptiles from north-east Mexico: description, systematics, assemblages and palaeobiogeography. Karlsruhe (2007) Gates, Terry A.: The Late Jurassic Cleveland-Lloyd Dinosaur Quarry as a Drought-Induced Assemblage. Palaios, Vol. 20 (2005); pp. 363-375 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 10, 2015 0:12:00 GMT 5
Those appear to be too few caudals indeed.
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Post by coherentsheaf on Feb 10, 2015 0:14:29 GMT 5
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Post by theropod on Feb 10, 2015 1:02:53 GMT 5
None at al, whoever digitized the paper for the biodiversity heritage library did the OCR, I just copied the table and corrected a few obvious errors.
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Top Dog
Feb 10, 2015 10:00:15 GMT 5
Post by Grey on Feb 10, 2015 10:00:15 GMT 5
I think that the 94 cm measurement of the Tübingen skull is the snout tip to occipital length as this is the one Noé used as comparison with the 1.23 m long skull specimen.
Incidentally, if Noé assumes a 1.6 ratio, the commun size estimate of 6.39 m for this 1.23 m skull is an underestimate.
I'm just checking one of his emails and he says "Liopleurodon got up to about 10m total length, and has an approximate head:body ratio of 1:6 (the 1:4 or 1:5 applies to the Cretaceous pliosaurs which have relatively bigger heads, 1:6 is more representative of Jurassic pliosaurs)."
Martill says as well the largest Liopleurodon specimens he knows are 10 m long.
I don't know from which skull it is based, but this is another hint that even for the well preserved Liopleurodon specimens, 1/5.19 is not the most likely ratio to use and 6.4 m is not a maximum length for L. ferox.
Yes theropod, teeth size really appears to be unreliable. The sizes are vastly different in size depending the individual and the method of measurement compliates this.
I think that suggestions of super-giants pliosaurs based on large tooth (Martill says one extremely large (but badly preserved tooth in the NHM could certainly come from a pliosaur about 20 m) is not due to precise calculation but to a secure educated guess.
Also, the position itself can complicate this and all teeth in all pliosaurs aren't preserved.
I was watching at the 'Pliosaurus grandis' tooth and even though it is just as large as the largest Kronosaurus teeth, I have the impress that the crown is quite short in it, that does not seem to be a long crowned tooth like the usual largest pliosaurs teeth. So I wonder if this 30.5 cm tooth couldn't represent a not so large specimen in the dentition. Of course, that's impossible to verify at the moment.
The comparison with the numerous immatures specimens of Allosaurus is very interesting. You can note BTW that Benson 2013 does not reject the possibility that truly adults specimens have to be found.
It is not that impossible indeed, pliosaurs are pretty rare fossils after all, even rarer when well preserved with indications of their ontogentic stage.
We discussed this with coherentsheaf and found that unfortunatel the Westbury fused sutures are located in the skull, they don't say anything about potentially fused centra in the specimen.
But I think, I'm not sure though, to have read that the Aramberri pliosaur had unfused bones in the remains of its skull as well.
Anyway, you start to thinking that Buchy's suggestion about pedomorphy could indeed be outdated at this point ?
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Top Dog
Feb 10, 2015 14:58:53 GMT 5
Post by tripoliraider1975 on Feb 10, 2015 14:58:53 GMT 5
Hello everyone
I am little bit confused about which skull measurement one has to take into account to estimate the size of pliosaurs.
As mentioned earlier, the largest Liopleurodon skull we know about belongs to NHM R3536. It's CBL is 125.6 cm but the "extreme mandible length"/"length from quadrate to tip of the snout"(quote) is 154 cm. With the 1:5.19 ratio, the TL could range from 6.56 m to about 8 m. However, with the 1:6 ratio, it goes from 7.5 meters (based on CBL) to 9.2 meters (based on "extreme mandible length").
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blaze
Paleo-artist
Posts: 766
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Post by blaze on Feb 10, 2015 16:39:03 GMT 5
CBL is the measurement used when estimating body length. GreyI don't know, irrespective of what Martill and Noe have responded in emails, none of what they say seems to be supported by the literature, not even by Noe's own publication. Using the largest skull we have, even assuming the 1.6 ratio, as tripoliraider1975 mentioned above, it would only "grow" to 7.5m, how do you get to 10m? perhaps using the wrong skull dimension and rounding up? perhaps Martill was thinking of the estimates using the old 1:7 ratio and using the wrong skull dimensions made by Foster? This is just weird. |
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Top Dog
Feb 10, 2015 17:40:11 GMT 5
Post by theropod on Feb 10, 2015 17:40:11 GMT 5
Well, obviously this is very uncertain as of now, but I ’ve become more sceptical about it.
• So far no detailed anatomical comparisons have been made between those supposed paedomorphics. There have been suggestions for the incompletely prepared material from aramberri, and separate reports for other pliosaurs, but nobody as of now directly compared them. Sadly, this is not testable at the moment.
• Considering the examples outlined earlier, as well as the relative scarcity of large pliosaurs, it seems less of a stretch that there really are the kinds of collection biases that would serve to explain it without assuming pliosaurs never reached osteological maturity. This point would benefit from finding data on how widespread immature features really are in pliosaurs. Also, a biomechanical explanation or non-explanation of why giant pliosaurs should remain osteologically immature throughout their lifes.
• If it did retain paedomorphic features, that could also imply they correlate with what they correlate with in immature individuals: fast growth. In that case, the specimen may be adult, but it doesn’t change what phase of growth it is in.
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Top Dog
Feb 10, 2015 18:19:17 GMT 5
Post by theropod on Feb 10, 2015 18:19:17 GMT 5
There’s more tough: ––––––––––––– " In the course of this study it was also noticed that there
is an apparent variation in the fusion of mandibular
elements in Pliosaurus. In the relatively small skulls such
as P. brachydeirus (OUMNH J.9245) and P. brachyspon-
dylus (CAMSM J.35991), the coronoid is not fused to
the medial face of the dentary, in contrast to the larger
skull P. macromerus (NHMUK 39692), in which they
are firmly fused. However, in BRSMG Cc332 (Pliosaurus
sp.), which is similar in size to P. macromerus (NHMUK
39692), fusion is similar to that found in P. brachydeirus
and P. brachyspondylus. Whilst this variability in fusion
may be indicative of ontogenetic stage, it is also possible
it has taxonomic significance or varies interspecifically.
A larger sample of specimens would be needed to deter-
mine this." Knutsen 2012: p. 266 ––––––––––––– ––––––––––––– " The dentition was
not described from PIN 426 so it is not possible to refer
it to Pliosaurus on the basis of tooth morphology; how-
ever, it is possible that this species is the same as Pliosau-
rus rossicus (PIN 304/1) based on their similar sizes and
stratigraphic co-occurrence. One difference with P. ros-
sicus (PIN 304/1) is that the cervical neural arches of P.
irgisensis (PIN 426) are fused to the centrum (Storrs et
al., 2000, p. 193, fig. 11.2), suggesting osteological matu-
rity." Knutsen 2012: p. 273 ––––––––––––– ––––––––––––– " Ontogeny
In the vertebral column of PMO 214.135 and PMO 214.136,
none of the neural arches are fused to their centra. It is
noteworthy that the fusion of neural arches with vertebral
centra has not been observed in any of the Pliosaurus
specimens examined in this study, nor has this been previously
reported for any other of the large pliosaurids (e.g., Philips,
1871; Tarlo, 1959 a and b; 1960; Halstead, 1971; Buchy, 2007),
and it is therefore difficult to determine whether this is truly
a reliable indicator of a juvenile or whether it is possibly a
paedomorphic feature in pliosaurids. The humerus of PMO
214.135 has a distinct tuberosity that is partially separated
from the capitulum, suggesting it is a mature individual
(Brown, 1981). The coracoid bears a well developed anterior
process, normally seen in adult specimens, when present
(pers. obs., EMK). Wiffen et al. (1995) discussed potential
histological indicators of ontogeny in a Late Cretaceous
elasmosaurid and a pliosauroid. They noted that adult
specimens had an osteosclerotic pattern of growth compared
to the pachyosteosclerotic bones of juveniles (but see
discussion in Liebe & Hurum, 2012). The cervical vertebral
centra of PMO 214.135 and PMO 214.136 display a clear
osteosclerotic state with a very spongy internal structure. Thus,
morphological and histological characters indicate that both
Svalbard specimens were adult individuals." Knutsen et al. 2012: p. 239 ––––––––––––– • There are pliosaurus specimens with fused neural arches (Knutsen 2012). The question is, how large do they get? • There indeed appear to be many giant pliosaurs with unfused ones. In the case of P. funkei, these are hypothesized to have been adults nevertheless, based on other features. The question however is, if features otherwise universally associated with immaturity are not applicable, how was it possible to even find a correlation between maturity and these other traits (such as muscle insertions and vertebral histology)? after all, there would be no way of distinguishing between adult and juvenile in the first place. • Cranial coossification is variable, but based on the available material it seems loosely correlated with size. If their skulls fused with age, does that mean their vertebrae did too? I’ve found the description of the westbury pliosaur: www.researchgate.net/publication/263564753_Cranial_anatomy_taxonomic_implications_and_palaeopathology_of_an_Upper_Jurassic_Pliosaur_%28Reptilia_Sauropterygia%29_from_Westbury_Wiltshire_UK––––––––––––– " BRSMG Cd6172 was an old, possibly female, pliosau-
rian, of large size, with many fused sutures and a
suite of age-related pathologies, including arthrotic
disease of the articulars, which caused prolonged jaw
misalignment. Evidence of pathological damage from
maloccluded teeth in both lower and upper jaws sup-
ports this hypothesis. Disease possibly weakened the
right jaw articulation sufficiently to cause a perimor-
tem fracture." ––––––––––––– This contains detailed skull measurements: onlinelibrary.wiley.com/store/10.1111/j.1475-4983.2012.01151.x/asset/supinfo/PALA_1151_sm_TableS1-S6-and-AppendixS1.pdf?v=1&s=88caae7f3a1507c4b617eec49594134ce082a7ef––– References:Knutsen, Espen M.; Druckenmiller, Patrick S.; Hurum, Jørn H.: A new species of Pliosaurus (Sauropterygia: Plesiosauria) from the Middle Volgian of central Spitsbergen, Norway. Norwegian Journal of Geology, Vol. 92 (2012); pp. 235-258 Knutsen, Espen M.: A taxonomic revision of the genus Pliosaurus (Owen, 1841a) Owen, 1841b. Norwegian Journal of Geology, Vol. 92 (2012); pp. 259-276 |
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Post by Grey on Feb 11, 2015 8:54:23 GMT 5
Giant partial Liopleurodon pliosaur tooth from the NNHM, shared on the Kronos Rising fanpage by Dr. Adam S. Smith. More details later in the week. This tooth looks really monstrous, that's the biggest pliosaur tooth I have yet seen. They have reportedly larger specimens.  |
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