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Post by theropod on Jul 16, 2018 21:12:34 GMT 5
^First of all, yes, I did want to see that source, Thanks. Seems pretty similar to one I got off of a 3d model on DA a long time ago (~2.9m³at 10m).
In both cases though, I’d be interested in what the dorsal views actually base on, or whether they are just guesses.
Also Torvosaurus has pneumatic cervicals and anterior dorsals. In Carcharodontosaurids and Tyrannosaurids all dorsals and at least part of the sacrum and even tail are pneumatic. Why is it that those GDI values assume the same density for the torso segments of animals that evidently had large abdominal airsacks and literally two to three times as many pneumatic vertebrae as for ones that did not?
What’s supposed to be better about centrum height than width for estimating size? It just seems to be nitpicking the lower figure to me, but that is ignoring that that’s probably just comparing it to the wrong measurement to begin with.
ML 1100 has a centrum height of 129mm medially, 145mm at maximum height and width of 121mm
MUJA-1913 has a centrum height of 150mm and width of 140-145mm
I do trust Rauhut and colleagues to be able to compare a measurement to an equivalent measurement, as well as estimate an incomplete centrum width without going totally overboard. It doesn’t take a phd to see that the width figures are much more consistent with the centrum height of MUJA-1913 being taken at the neural canal than at the base of the neural arch. But I can ask him when I see him at SVPCA if you want.
Anyway, taking both into account it’s closer to 17% bigger than 18%. If we just compare the geometric mean of height and width (150*142.5 vs 129*121 we get 17% so I guess 11.7m then, and 4.3t when based on the mass estimate you cited.
About the second post, do you even need to ask?
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Post by Grey on Jul 31, 2018 16:19:36 GMT 5
Is there any material suggesting something larger than 15 m and 7.5 tonnes for Spinosaurus ?
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Post by theropod on Jul 31, 2018 16:43:50 GMT 5
Given MSNM V4047’s 99cm rostrum, the length I am getting for Ibrahim et al.’s skeletal reconstruction is actually 16.4m when measured through the neural canal, but nothing substantial suggests a greater body mass, no. The length is highly susceptible to variation based on minor measuring errors though, because the resolution is really quite poor. I’ve seen people get lengths closer to 15m when scaling it, but those seem to actually scale the rostrum larger than what is actually indicated on the composite.
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Post by Grey on Jul 31, 2018 18:08:22 GMT 5
Nothing to suggest the genus would be actually heftier ?
Nowadays, what are the biggest fragmentary carcharodontosaurids ?
Last time I checked, there is one Mapusaurus bone that suggests, maybe, a Sue-sized (in mass) specimen (discussion with Franoys).
There is also the alleged abelisaurid 115 cm print. Isn't the 12 m figure reported here and there somewhat conservative if it really comes from a 115 cm foot ?
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Post by theropod on Jul 31, 2018 19:20:24 GMT 5
Well, the whole Ibrahim et al. reconstruction is still questioned at this point (Evers et al. 2015). But given this restoration is correct, no. Evers, S. W., O. W. Rauhut, A. C. Milner, B. McFeeters, and R. Allain. 2015: A reappraisal of the morphology and systematic position of the theropod dinosaur Sigilmassasaurus from the “middle” Cretaceous of Morocco. PeerJ 3:e1323.I suppose you are referring to this→? Given the generally appalling scientific quality of this report, it’s hard to be sure of anything really. Is there any more reliable documentation out there? But if this is an actual 115cm footprint that is not significantly enlarged, 12m is definitely an underestimate. However a more detailed documentation would help to determine whether the prints are underprints and/or taphonomically altered. Sue-sized footprints from Hell Creek are a little over 70cm, and a few around that size or slightly larger are known from the Upper Jurassic, which were presumably from very large theropods in their own right (Brochu 2003, Manning et al. 2008, Boutakiout et al. 2009, Rauhut et al. 2015)… Also I wouldn’t be sure of its Abelisaurid affinities at all (footprint morphology isn’t very taxonomically informative on its own, and while different footprint morphotypes might be recognizable, relating them to taxa below the level of theropoda is generally difficult without basing it on provenance and age). There is also the presumed sue-sized Giganotosaurus’ dentary, a possibly sue-sized or larger Carcharodontosaurus skull, depending on that taxon’s morphology, which remains too incompletely known to reliably reconstruct… EDIT: and by the seem of it, a conservatively sue-sized Allosaurus→. |
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Post by Grey on Jul 31, 2018 19:55:01 GMT 5
Yup, I never understood their obligate id as abelisaurid. Carcharodontosaurid would make more sense. Is there a study planned for this one ?
Which Carcharodontosaurus skull ? The one Sereno found ?
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Post by theropod on Jul 31, 2018 20:05:17 GMT 5
Yup, I never understood their obligate id as abelisaurid. Carcharodontosaurid would make more sense. Is there a study planned for this one ? no idea, I was going to ask you that since you brought it up. Which Carcharodontosaurus skull ? The one Sereno found ? Yes |
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Post by Deleted on Aug 2, 2018 1:50:50 GMT 5
Is there any material suggesting something larger than 15 m and 7.5 tonnes for Spinosaurus ? Going by the most likley/accurate reconstructions... no. The updated GDI that has been done on it suggests 6.9 tonnes for the largest Spinosaurus, solidly placing it within the same tier as the largest Carcharodontosaurinae theropods. (atleast the ones that aren't estimates from tiny shitty fragments) |
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Post by Deleted on Aug 2, 2018 2:04:26 GMT 5
Well, the whole Ibrahim et al. reconstruction is still questioned at this point (Evers et al. 2015). But given this restoration is correct, no. I suppose you are referring to this→? Given the generally appalling scientific quality of this report, it’s hard to be sure of anything really. Is there any more reliable documentation out there? But if this is an actual 115cm footprint that is not significantly enlarged, 12m is definitely an underestimates. However a more detailed documentation would help to determine whether the prints are underprints and/or taphonomically altered. Sue-sized footprints from Hell Creek are a little over 70cm, and a few around that size or slightly larger are known from the Upper Jurassic, which were presumably from very large theropods in their own right (Brochu 2003, Manning et al. 2008, Boutakiout et al. 2009, Rauhut et al. 2015)… Also I wouldn’t be sure of its Abelisaurid affinities at all (footprint morphology isn’t very taxonomically informative on its own, and while different footprint morphotypes might be recognizable, relating them to taxa below the level of theropoda is generally not possible without basing it on provenance and age). There is also the presumed sue-sized Giganotosaurus’ dentary, a possibly sue-sized or larger Carcharodontosaurus skull, depending on that taxon’s morphology, which remains too incompletely known to reliably reconstruct… The Giganotosaurus dentary is only 3mm thicker than that of the Holotype going off of listed measurements, with such a small difference I would say the specimen wasn't much bigger if at all than the Holotype. I see no reason to assume SGM Din 1 was Sue sized or larger. Its skull is no larger than that of the 6.4 tonne tyrannotitan or the 6.8 tonne Giganotosaurus holotype. (while most mass estimates right now put Sue around the 9 tonne mark) |
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Post by creature386 on Aug 8, 2018 15:18:23 GMT 5
The Giganotosaurus dentary is only 3mm thicker than that of the Holotype going off of listed measurements, with such a small difference I would say the specimen wasn't much bigger if at all than the Holotype. Why do you think thickness is a more reliable for estimating the size than length (as you should know, the dentary is about 8% longer than the holotype's)? |
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Post by theropod on Aug 8, 2018 15:25:34 GMT 5
It was apparently sufficiently bigger to warrant a paper specifically about its size from the only people who actually examined both specimens first hand, so I think that it is bigger is pretty clear. That being said, I asked Coria about it, and he doesn’t seem to recall how they measured the 8% figure (the thing is, the paper, doesn’t actually specifically state a dimension, it states the 8% was "on average") but retains that the specimen is bigger, offering a guess of 5%.
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Post by Deleted on Aug 13, 2018 23:05:43 GMT 5
The Giganotosaurus dentary is only 3mm thicker than that of the Holotype going off of listed measurements, with such a small difference I would say the specimen wasn't much bigger if at all than the Holotype. Why do you think thickness is a more reliable for estimating the size than length (as you should know, the dentary is about 8% longer than the holotype's)? Im not sure the 8% figure is legit. It can't be replicated by the scale bars on the images given by the paper for one. |
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Post by theropod on Aug 14, 2018 1:20:22 GMT 5
That doesn’t mean anything, scalebars are usually only very approximate in terms of accuracy.
Their purpose is not to allow people to take precise measurements from the photographs (which is problematic due to parallax anyway), they are to give an idea of the scale of the thing they are looking at without having to look up the measurements.
Some are quite accurate and good enough to use for more than just that, but you cannot automatically assume that. The Giganotosaurus holotype’s skull is 1.7m long going by the scalebar in the original description paper…
They hardly made their measurements up out of thin air, and they are the ones who actually had access to measure the specimens…
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Post by Deleted on Aug 14, 2018 4:54:54 GMT 5
Even if it is 8% bigger?.. that doesn't mean the whole specimen is that large overall. (Ill discuss more on this topic later)
For example, Tyrannosaurus Sue isn't 17% bigger than the T.rex holotype even though it's dentary would suggest it was indeed that large.
Minor size differences of a few mm or cm in isolated bones shouldn't be used to get super sized fragmentary dinosaurus is what im saying.
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Post by theropod on Aug 17, 2018 12:22:58 GMT 5
The publication of Henderson’s talk at SVPCA 2016 is out now: peerj.com/articles/5409/15.5m/6.5t, pretty much as expected |
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