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Post by Deleted on Sept 18, 2014 21:28:59 GMT 5
Spinosaurus is quite bulky and with a barrel-like rib cage, in contrast to previous assumptions that it was quite thin and gracile.     I can't measure it exactly due to the angle, but it seems that the width is approximately equal to the depth of the rib cage. This is gonna be a surprisingly voluminous and heavy dinosaur, I can tell. |
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Post by creature386 on Sept 18, 2014 22:08:37 GMT 5
  Does this really look more heavily built than previously thought? It actually looks thinner than the previous reconstruction (unsurprising, since this is a juvenile). |
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Post by Deleted on Sept 18, 2014 22:38:34 GMT 5
Does this really look more heavily built than previously thought? It actually looks thinner than the previous reconstruction (unsurprising, since this is a juvenile). I judge bulkiness by torso bulk, not relative to length. Also, it has been previously assumed, at least by Scott Hartman, that Spinosaurus was sort-of slab-sided.
"From the front I think the torso would be taller than wide (even ignoring the sail), so I don't think the mass would be as...well...massive as it looks in side view."The comment was made back in 2013. Then 2014 rolls by and gives Spinosaurus a fat barrel chest. Sure, the spines would have uplifted the back to some degree and made the torso deeper than wide, but he stated that "torso depth > torso width" even when ignoring the spines. Also, ditch that tucked-in belly, it's leftover GSPaulianism. The neck is also a bit shrinkwrapped if you ask me. An adult would likely be bulkier, as non-avian theropod dinosaur juveniles tend to be more gracile than the adults. |
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Post by Infinity Blade on Sept 19, 2014 0:37:51 GMT 5
It would have been quite a sight to see Spinosaurus facing off against the giant fish it hunted and even crurotarsans (Sarcosuchus) in the water.
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blaze
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Post by blaze on Sept 19, 2014 2:09:03 GMT 5
The torso is very shallow, that's why it looks round.
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Post by theropod on Sept 19, 2014 2:14:28 GMT 5
The ribs themselves are very shallow, but that’s because they are laterally extensive and don’t encompass the whole body cavity dorsoventrally.
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Post by Grey on Sept 19, 2014 7:59:45 GMT 5
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blaze
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Post by blaze on Sept 19, 2014 9:27:59 GMT 5
It doesn't seem like the rim to rim measurement is going to account for the 27% difference. And they should have wrote that in their paper.
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Post by theropod on Sept 19, 2014 17:46:39 GMT 5
Foreshortening is a factor, but it should not affect the ilium, which is paralell to the vertebral collumn (if anything the ilium should look bigger since it’s closer to the viewer than the vertebrae) and unless they gave it a very strong deviation from the vertical the effect isn’t going to be huge on the femur and other long bones either (most people in seem to just assume parasagittal posture because it comes close enough). For what it’s worth I just tried measuring the other skeletal (the one from the paper itself, which was also posted in the response of the authors), and even when I follow the rim-to-rim (I assume that what they mean is probably in straight line, even though I’m still not convinced that’s the measurement that Charig and Milner designated as rim-to-rim in their osteology of Baryonyx) and measure the ilium in its greatest dimension and the vertebrae (dorsals 6 through 8) as conservatively as possible the ilium still comes out too small. The authors are defending their position that Spinosaurus was a semiaquatic piscivore with reduced legs, but that doesn’t seem necessary since nobody ever seriously doubted that (and I think that based on their table the neotype ilium is smaller than that of the Allosaurus topotype is a clear demonstration of that, so no need to make it even smaller). The quantifyable proportions are the real issue. This part sounds good: "We are working on a monograph that
will include detailed descriptions and more measurements, as well as large amounts of unpublished data."→ |
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Post by creature386 on Sept 19, 2014 19:21:53 GMT 5
The torso is very shallow, that's why it looks round. Are you referring to the Dal Sasso reconstruction which I called bulkier or to the new one where broly claimed it to be more heavily-built? |
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blaze
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Post by blaze on Sept 19, 2014 22:03:30 GMT 5
the new one
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Post by spinodontosaurus on Sept 20, 2014 2:13:00 GMT 5
To me the rib cage looks broad because the ribs are articulated differently to how Andrea Cau portrayed them, close to what I could do with the little I had (although I don't believe I ever posted it anywhere). This has the affect of widening the rib cage, but making it less deep, for a minimal change in mass overall (as per Bates et al., 2009).
Also of note, the femur may be short, but it's pretty robust. Although the photograph Hartman posted isn't ideal, it still looks as though the femur is at least thick as anything belonging to an Allosaurus, Daspletosaurus or even Suchomimus.
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Post by Grey on Sept 20, 2014 9:37:02 GMT 5
I think the level of antagonism toward this paper has been excessively high. It is justifiable to discuss the potential issues in it but certainly behind the educated thoughts of Hartman and others, there is always the internet dino-mob for who the version of Spinosaurus from Ibrahim et al. does not correspond to their version, closer to a kaiju's depiction than an actual dinosaur. Hopefully, more details, analysis, measurements and stuff will follow in the next days and months. But really, people should be at least as cautious with Hartman's observations, made in one day, than with Ibrahim et al. study, made in several years.
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blaze
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Post by blaze on Sept 20, 2014 10:28:42 GMT 5
theropodI think straight-line rim to rim is accurate after the scaling I did on Baryonyx vertebral column, "over the curves" rim to rim seems to cryptic a measurement and of top of that it'll result in an even smaller total length estimate than Cau's and mine of ~7.5m. I wonder how much of that unpublished material is Suchomimus material, it's been 16 years! when are we going to see a proper monograph of Suchomimus? it's known from several individuals of various ontogenic stages and there was new material found some years ago. I completely dislike that Sereno does that, every single new dinosaur he names in which he is the lead author never gets any follow up from the 2-page long science/nature article.
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Post by theropod on Sept 20, 2014 14:33:10 GMT 5
I think the level of antagonism toward this paper has been excessively high. It is justifiable to discuss the potential issues in it but certainly behind the educated thoughts of Hartman and others, there is always the internet dino-mob for who the version of Spinosaurus from Ibrahim et al. does not correspond to their version, closer to a kaiju's depiction than an actual dinosaur. Hopefully, more details, analysis, measurements and stuff will follow in the next days and months. But really, people should be at least as cautious with Hartman's observations, made in one day, than with Ibrahim et al. study, made in several years. We are that sceptical about it. It’s just that Hartman’s observations happen to be replicable–in fact the very thing he criticised is that he cannot replicate the digital skeletal using the published measurements, and I cannot either. And qilong also does have a point in saying that something is fishy about an alledged quadruped whose forelimbs have not been described as having any adaptions for quadrupedalism (and have in fact been described to be very similar to those of the biped Baryonyx), doesn’t he? The very point is that there’s a lot of scepticism (not "antagonism") towards the interpretatio The bulk (and certainly the most valuable and interesting parts) of Ibrahim et al.’s work is not the part that is affected; they provide information on previously unknown parts of the osteology and bone histology indicating that Spinosaurus was certainly semiaquatic, had very short legs and a long, low slung body, very dense bones and a top 1/3 of the spines covered in skin). But you cannot deny certain aspects (such as the odd proportions shown in the skeletal and the popular depictions that base on it, which you’ll find mushrooming up everywhere atm) deserve discussion, and that other aspects (taxonomy) will always be debated.
REFERENCES:Hartman, Scott (2014): There's something fishy about the new Spinosaurus. www.skeletaldrawing.com/home/theres-something-fishy-about-spinosaurus9112014 Accessed 20.09.2014 Headden, Jaime (2014): The Outlaw Spino Saurus. qilong.wordpress.com/2014/09/12/the-outlaw-spino-saurus/ Accessed 20.09.2015 Ibrahim, Nizar; Sereno, Paul; Dal Sasso, Christiano; Maganuco, Simone; Fabbri, Matteo; Martill, David; Zouhri, Samir; Myhrvold, Nathan; Iurino, David: Semiaquatic Adaptions in a Giant Predatory Dinosaur. Science, published online (2014); pp. 1-6 |
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