Spinosaurus News ~

[tigerluver]

(09-09-2020, 07:02 AM)DinoFan83 Wrote: As for the pubis vs skull measurement, both of the models appear very similar in that regard, as well as in skull/quadrate length to pelvic depth ratios; the width of the pubis is not really relevant so much as its length so if either has a pubis that is too thick or thin it does not affect the mass with correction. It seems moreso to me that the new model is more massive due to the above reasons (wider torso, lesser pneumaticity, bigger tail, and so on).

Regarding that forelimb, I have heard about it as well, and the anteroposterior view of the humeral shaft is pretty much identical to that of NMC 41852, so once it gets described it should be helpful to scale NMC 41852.
However, Spinosaurus would have almost certainly been bipedal. In addition to theropods being unable to pronate their hands, here is a quote from Jaime Headden that explains that well:

"First, the forelimbs, if they are anything like normal theropod forelimbs, are completely unsuited for weight-bearing. Rather than arranged vertically, the shoulder blades are aligned across the ribs in such a way that any quadrupedal stance would shove the shoulders deep into the neck and likely behead a Spinosaurusfaster than Sean Bean in his next deat–film. Rather, they were suspended as in other theropods free from the ground, to dangle as they please.
Second, the authors even provide a furcula (recovered with the spinosaur Suchomimus tenerensis) for the shoulder, and this would have kept the shoulders from moving independently of one another, meaning it is unlikely the arms were permitted to walk in anything like a natural gait or a “typical” quadruped.
Third, the forelimbs while massive have not been described in sufficient detail and appear to possess characteristic typical of other spinosaurs. If they are anything like the forearms of Baryonyx walkeri, they’d lack almost any quadrupedal attributes, especially in the metacarpus, manus, and especially in the phalanges. The authors propose a semi-knuckle-walking locomotion style, but all extant knuckle-walkers have specific adaptations of the arm to permit this (and so it appears in extinct ones, even if you include chalicotheres which may not have been knuckle-walkers), including the presence of thickened, columnar first phalanges and strong curling joints for the other phalanges to bring them out-of-the-way, as well as thickened, solid wrists. Theropods, rather, have flexible wrists due to the semilunate carpal hinge and would likely have been unable to bear weight translating through the upper into the lower arm, much less straighten the limb passively enough to bear weight in such a fashion that a knuckle-walker would require."

Sorry, I don't follow on the proportions. What osteological measurements have resulted in the Ibrahim et al. reconstruction being so much wider in the lateromedial axis? The wider torso has to be a function in part of the pelvic girdle (lateromedial diameter) as we don't have a scapula one would think. IIRC, the centrums of spinosaurus were quite thin as well compared to say T. rex. Reply