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Post by Grey on Sept 20, 2014 19:36:01 GMT 5
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Post by theropod on Sept 21, 2014 3:47:36 GMT 5
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Post by Infinity Blade on Sept 21, 2014 5:33:47 GMT 5
I'm sort of confused now, what then really was Spinosaurus like?
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Deleted
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Post by Deleted on Sept 21, 2014 9:50:45 GMT 5
After reading it, I think it makes total sense for most of the spines to be encased in tissue, so it would stand up to greater water drag/forces. Probably explains why the texture that suggested a sail is only located at the topmost third of the spines, as well as being broad rather than rods... A half-ridge, half-sail(referring to the part of the dorsal spine that was likely visible in life) is better protected against the force of water flow than just a skin sail. |
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Post by theropod on Sept 21, 2014 15:06:47 GMT 5
Yes, as noted in one of the posts bone is a costly material. If it was only for display, it would really look like Dimetrodon’s. But if it was used for hydrodynamic purposes and ligament attachments, it would have been subjected to far greater forces.
@macronectes: We don’t know that much more than before, except for the shorter legs. Legs being as short as shown in the skeletals or obligate quadrupedalism are being debated right now, until a conclusion is reached we should prefer the bipedal posture for obvious reasons.
Apparently it had a very unusual foot morphology if you count that (perhaps not so easily visible though, at least on land), and its ribcage was roughly semi-circular in crossection based on the mount. And there are some parts of the skull and mandible that are known know, but remain to be described, and which may or may not help with the proportions of its skull.
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Post by theropod on Sept 23, 2014 1:45:14 GMT 5
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stomatopod
Junior Member
Gluttonous Auchenipterid
Posts: 182
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Post by stomatopod on Sept 24, 2014 3:05:42 GMT 5
Another post on Theropoda.
Maganuco estimates Spinosaurus at 6 tons.
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Post by Godzillasaurus on Sept 27, 2014 2:27:45 GMT 5
What other fragments did they find with the leg remains? That means a lot in how accurate the reconstructions or skeletals may be.
If there was nothing else found, then that certainly could have been a juvenile. Just something to think about
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Post by Godzillasaurus on Sept 27, 2014 2:35:49 GMT 5
Theropod, so there is more skull material that we don't even know about yet!? Cool!
I must add though that what we know of the rostrum, mandible, and teeth already would be able to support both land-based OR water-based feeding; either way we can make firm speculations as to how it caught fish, and being less restricted to living on land with a supposedly more crocodile-like niche would not alter much aside from how far it would have to lower its head and its versatility in deep water.
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Post by theropod on Sept 27, 2014 4:25:06 GMT 5
Yes, Ibrahim et al. mention (but haven’t properly described yet) fragments of the nasals, prefrontals, squamosals and quadratojugals, most of both quadrates, a "possible lacrimal and parts of the dentaries. How much those can tell us will have to wait until they publish their monograph.
What do you mean "restricted to living on land"?
The current reconstruction is the restricted one, it restricts it to live in water.
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Post by creature386 on Sept 27, 2014 13:51:39 GMT 5
Well, restricting it to one thing can also mean less restricting it to the other, so what Godzillasaurus said makes sense.
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Post by Godzillasaurus on Sept 28, 2014 0:47:33 GMT 5
I just got a new National Geographic in the mail today, and it was about the new discoveries of spinosaurus! I just skimmed it, and it does in fact seem that the new leg material was in fact found with more vertebrae and skull pieces among a few others if I recall correctly.
theropod, it is less restricted to living on land than previous reconstructions and drawings, which exhibited more typical theropod characteristics save for its elongated skull and raised vertebrae. The new findings propose that it was far better adapted for life in the water, but that at the same time does not mean it was restricted to the water. The knuckle-walking idea is conceivable.
It seems that spinosaurus has gradually become more and more bizarre over the years; at first it was described almost as an allosauroid with a heightened spinal column, and then evidence of an elongated snout and conical teeth came in, and now it is proposed that it would have walked on land bipedally.
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Post by theropod on Sept 28, 2014 2:34:40 GMT 5
Why don’t you simply read the paper, or the supplementary material? The knuckle-walking hypothesis is problematic. You should find the link to Jaime Headden’s explanation somewhere on the last few pages of this thread (or, just search for "Spinosaurus the bite stuff" and you’ll find it). I used to consider it realistic too, but it seems I was too naive believing knuckle walking didn’t require major adaptions. Andrea Cau’s ad hoc-hypothesis→ of a bipedal Spinosaurus with a high-craned neck, somewhat erect body and retracted forelimbs shifting the COM backwards sufficiently makes more sense to me (luckily that’s somewhat independent of hindlimb size), especially if we also believe Headden on the matter of tail vertebrae. Still, I such a large and tiny-legged animal would be largely limited to the water My point is that the previous reconstructions are not restricted to live on land. The animal could probably propel itself through water just as well (if not better, because its longer legs would make it easier to reach the ground in deeper water). Those short legs aren’t an immediate adaption to water, they only make sense on the long term, in conjunction with other adaptions for swimming (which haven’t been described yet beyond what we already knew). That, in turn, only makes sense if the animal gave up locomotion on land in favour of adapting to water. Spinosaurus was never described as an allosauroid with heightened spinal collumn. Early reconstructions merely showed it with a deeper skull (because that’s the norm for other theropods, not because they knew or claimed to know anything about Spinosaurus), that’s all, but it didn’t base on any material and was never conceived as anything but baseless speculation. I don’t think we can really say it "has become" anything if that never based on any material or was postulated with any confidence in the first place. Oh, and a quadrupedal Spinosaurus has been proposed before (Bailey 1997). So has a quadrupedal Baryonyx btw (Charig & Milner 1997, probably the paper I’m citing most these days…), but both were before people knew enough about the forelimbs of non-avian theropods (still assuming them to be pronated and essentially like mammal forelimbs).
References:Bailey, Jack B.: Neural Spine Elongation in Dinosaurs: Sailbacks or Buffalo-Backs?. Journal of Palaeontology, 71 (1997); 6; pp. 1124-1146 Charig, Alan J.; Milner, Angela C.: Baryonyx walkeri, a fish-eating dinosaur from the Wealden of Surrey. Bulletin of the Natural History Museum, London (Geology), vol. 53 (1997); 1; pp. 11-70 |
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Post by Grey on Sept 30, 2014 20:44:31 GMT 5
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Post by theropod on Oct 25, 2014 23:28:47 GMT 5
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