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Is it a quadruped, like what many people now think it is?
Well, I don't think it's a quadruped. The legs and hips are too small in their model.
www.skeletaldrawing.com/home/t…
According to Scott Hartman, the actual hips and legs are ~127% of their digital model dimensions. This shifts the center of gravity backwards, and long with the longer legs and larger pelvis, revives the bipedalism of Spinosaurus.
How far does the spine at the back extend?
I think it still extends to the tail by a degree, like the previous reconstructions. The sacrals, as well as most of the caudals, especially those that are situated closer to the hips, have not been found. I would give it a tall anterior caudal, based on this:
qilong.wordpress.com/2010/05/1…
(Scaling the holotype's alleged anterior caudal to the centrum length of the neotype's first anterior caudal seems to make the neural spine end up surprisingly short compared to the dorsal spines)
And with the large gaps in the caudal series, who's to say for certain that it isn't the case? That reddish-orange(holotype) caudal there that seems to restrict the extent of the spine? I shifted it two vertebral positions backwards, it ends up still far enough from the red caudals after it that this can't really be proven nor disproven, just moving it enough for a steep slope at the posterior end of the (extended) dorsal spine.
Neither the paper nor the supplementary information refutes the placement of the tall holotype spine as a caudal spine at all. They don't even mention reasons on why they place it as the last presacral spine, none, nothing. No mentions of it's placement anywhere in the main paper or the supplementary paper.
Is the spine a sail, a ridge, or a hump?
I think it's a ridge with a sail on top.
The surface striae(which they interpreted as signs of a sail in the main paper, along with sharp edges on the top)only cover the top ~33.3%(or 1/3) of the spine.
"proximal one-third of dorsal neural spines textured externally by vertical striae"
www.sciencemag.org/content/sup…
There's ~66.7% left for humps and ridges. The lack of vascularization in the bone would eliminate most if not all of thermoregulatory purposes. So no more Dimetrodon comparisons once and for all, it seems.
The chameleon had axial muscle covering roughly ~1/3 of it's spines, judging from the figures in the paper. Spinosaurus may have had the axial muscle a bit higher up proportionally, being a larger animal with a larger dorsal structure, which, due to the square-cube law, needs more support proportionally. I don't find it hard to imagine Spinosaurus having the lowest ~1/3 of it's spines completely buried in it's back, the middle ~1/3 being a ridge composed of likely adipose tissues, fat, whatever, etc. while the sail occupies the top.
So, what do you think Spinosaurus looks like overall?
Basically, I think of Spinosaurus as something like this:
It's a rushed, half-arsed edit, but you get the idea. I inflated the underbelly a bit because the original one looked a bit starved in that region. As for the back, it may look like I added too much flesh into it, but remember that it's not going to be a circular cross-section, it would have roughly looked like the commonly-depicted shape of a raindrop in cross-section, although quite a bit loosely. I also tweaked the angle of the shoulders to roughly match that of Scott Hartman's skeletal.
________________________________________
Spinosaurus is quite a sensitive topic for most of the dinosaur community, so I'll have to put this up here:
Comments are welcome, but no s**tstorms please. If you disagree with anything here, feel free to explain, but be cool in civil about it. No personal attacks, insults, condescending statements, and the like.
This isn't Youtube, and don't try to make this site anything like it. Any thoughts about insulting me, keep them to yourself. I'll ignore and/or hide any overly aggressive or condescending comment here. If you keep doing it too much, I'll block you.
And there will be NO comparisons with Tyrannosaurus, period. Any comment hinting at SvT will be removed at sight. We all know how s**t hits the fan when Spinosaurus and Tyrannosaurus are compared.
Just replace the Transformers with rabid Tyrannosaurus/Spinosaurus fanatics and you got a very good idea of the intensity of SvT flame wars.
Well, I don't think it's a quadruped. The legs and hips are too small in their model.
www.skeletaldrawing.com/home/t…
According to Scott Hartman, the actual hips and legs are ~127% of their digital model dimensions. This shifts the center of gravity backwards, and long with the longer legs and larger pelvis, revives the bipedalism of Spinosaurus.
How far does the spine at the back extend?
I think it still extends to the tail by a degree, like the previous reconstructions. The sacrals, as well as most of the caudals, especially those that are situated closer to the hips, have not been found. I would give it a tall anterior caudal, based on this:
qilong.wordpress.com/2010/05/1…
(Scaling the holotype's alleged anterior caudal to the centrum length of the neotype's first anterior caudal seems to make the neural spine end up surprisingly short compared to the dorsal spines)
And with the large gaps in the caudal series, who's to say for certain that it isn't the case? That reddish-orange(holotype) caudal there that seems to restrict the extent of the spine? I shifted it two vertebral positions backwards, it ends up still far enough from the red caudals after it that this can't really be proven nor disproven, just moving it enough for a steep slope at the posterior end of the (extended) dorsal spine.
Neither the paper nor the supplementary information refutes the placement of the tall holotype spine as a caudal spine at all. They don't even mention reasons on why they place it as the last presacral spine, none, nothing. No mentions of it's placement anywhere in the main paper or the supplementary paper.
Is the spine a sail, a ridge, or a hump?
I think it's a ridge with a sail on top.
The surface striae(which they interpreted as signs of a sail in the main paper, along with sharp edges on the top)only cover the top ~33.3%(or 1/3) of the spine.
"proximal one-third of dorsal neural spines textured externally by vertical striae"
www.sciencemag.org/content/sup…
There's ~66.7% left for humps and ridges. The lack of vascularization in the bone would eliminate most if not all of thermoregulatory purposes. So no more Dimetrodon comparisons once and for all, it seems.
The chameleon had axial muscle covering roughly ~1/3 of it's spines, judging from the figures in the paper. Spinosaurus may have had the axial muscle a bit higher up proportionally, being a larger animal with a larger dorsal structure, which, due to the square-cube law, needs more support proportionally. I don't find it hard to imagine Spinosaurus having the lowest ~1/3 of it's spines completely buried in it's back, the middle ~1/3 being a ridge composed of likely adipose tissues, fat, whatever, etc. while the sail occupies the top.
So, what do you think Spinosaurus looks like overall?
Basically, I think of Spinosaurus as something like this:
It's a rushed, half-arsed edit, but you get the idea. I inflated the underbelly a bit because the original one looked a bit starved in that region. As for the back, it may look like I added too much flesh into it, but remember that it's not going to be a circular cross-section, it would have roughly looked like the commonly-depicted shape of a raindrop in cross-section, although quite a bit loosely. I also tweaked the angle of the shoulders to roughly match that of Scott Hartman's skeletal.
________________________________________
Spinosaurus is quite a sensitive topic for most of the dinosaur community, so I'll have to put this up here:
Comments are welcome, but no s**tstorms please. If you disagree with anything here, feel free to explain, but be cool in civil about it. No personal attacks, insults, condescending statements, and the like.
This isn't Youtube, and don't try to make this site anything like it. Any thoughts about insulting me, keep them to yourself. I'll ignore and/or hide any overly aggressive or condescending comment here. If you keep doing it too much, I'll block you.
And there will be NO comparisons with Tyrannosaurus, period. Any comment hinting at SvT will be removed at sight. We all know how s**t hits the fan when Spinosaurus and Tyrannosaurus are compared.
Just replace the Transformers with rabid Tyrannosaurus/Spinosaurus fanatics and you got a very good idea of the intensity of SvT flame wars.
Volumetric estimate for Giganotosaurus
I had performed a volumetric analysis on my Giganotosaurus carolinii reconstruction to see how voluminous and massive it might have been, well, my take on it. This also has implications for its lifestyle in regards to a certain hypothesis claiming allosauroids to be obligate scavengers... Full blogpost: https://thesauropodomorphlair.wordpress.com/2022/01/09/volumetric-estimate-for-giganotosaurus/
Edwin's two-beamed sauropod
The diplodocid taxon Dystylosaurus edwini has long been commonly assumed to be a synonym of Supersaurus. But does this long-held idea still really hold up? Full blogpost: https://thesauropodomorphlair.wordpress.com/2021/05/28/edwins-two-beamed-sauropod/
Size of the duck titans
My take on size estimations for adult Edmontosaurus annectens. Some of them got real big... Full blogpost: https://thesauropodomorphlair.wordpress.com/2021/02/10/size-of-the-duck-titans/
Tetrapod body densities and updated mass estimates
Haven't gotten out a blog post in a while. Sorry for the hiatus, but it took some time to get the hang of Wordpress' block editor. Without further ado, here's the new post. New published data on tetrapod body densities, and updates to my previous mass estimations. Full blogpost: https://thesauropodomorphlair.wordpress.com/2021/02/05/tetrapod-body-densities-and-updates-to-mass-estimations/
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Hartman increased the leg size incorrectly as he didn't counter in perspective and outward angle of the femur. So if we assume that Ibrahim is correct in that the neotype is all one animal, then the legs are not too small. The main issue with Ibrahim's reconstruction is that they used isolated Sigilmassaurus material from the Kem Kem beds as well that might have different proportions. The neck, arms and tail are the areas from which we have the least material on Spinosaurus aegyptiacus.
I also do not believe the sail extended onto the tail. All vertebrae that are definite caudal I have seen do not have the hypertrophied neural spines like the dorsal vertebrae do. The holotype only has one caudal vertebra and that does not have a very long spine. I've also seen Spinosaurid dorsal vertebrae that have the neural spine curving strongly downwards, which would suggest the sail might end in front of the sacrum. Though time will only tell when we find more specimens. But my guess would be that the sail was more similar in shape to that of Edaphosaurus with a strongly curved caudal end than the sail we see here and in Ibrahim's reconstruction.
Though this might still be up for debate. I don't think there was much of a hump on the sail of Spinosaurus. Yes Chameleons might serve as a decent example. But those proportions might not scale. Chameleons are quite small, and Spinosaurus is obviously quite huge. My hunch would be that any hump would extend to around the widened areas on the lower end of the neural spines. Since there are no muscle attachments on the higher parts of the spines it's likely that there wasn't too much tissue.