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Post by spinosaurus1 on Mar 11, 2014 23:51:32 GMT 5
i was curious on knowing the strength of spinosaurus neck vertebra. despite having none, many people on carnivora argue that they weren't very strong and very insufficient. were there any evidence of this?
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Post by theropod on Mar 12, 2014 1:53:05 GMT 5
Stromer described cervical vertebrae of the S. aegyptiacus holotype. People inferred that from the fact that the centra are so much smaller than that of an analogous Tyrannosaurus vertebra. That in itself of course does not mean they were by any means "insufficient", that assertion is plain ridiculous. Tyrannosaurus and Spinosaurus are far from easily comparable in terms of vertebral morphology. For example Spinosaurus’ dorsal (I know, this is referring to cervicals, which are pneumatic, even in Spinosaurs) vertebare have apneumatic centra: Im Gegensatz zu den Halswirbeln sind sie im Innern nicht hohl, aber ebenfalls unten und seitlich, besonders seitlich weit oben stark konkav, d. h. ihre pleurozentralen Gruben (Nopcsa 1906, p. 6 1 ff.)sind tief und sehr weit.In contrast to the cervical vertebrae they [the dorsal vertebrae] are internally not hollow, but likewise below and laterally, especially laterally far above, strongly concave, i.e. their pleurocentral pits (Nopcsa 1906, p. 61ff.) are deep and very wide. Lower pneumatisation of course affects the resistance of structures, one that is hollow will have to be more voluminous to be as strong (and that’s what we see in Tyrannosaurus, presumably also with other bones, which is why it has such thick vertebrae and thick femora) as one that is solid, although the degree to which is a more complicated thing to calculate. To make up for their lack in centrum thickness (i.e. in second moment of area against bending in the dorsoventral plane), Spinosaur vertebrae have huge neural spines, which very likely severd as an anchor point for strong superspinal and nuchal ligament to give the necessary additional support (their hypertrophy can thus be explained by the overall size of the animal). The assumption is not a far fetched one that also the cervicals of Spinosaurus are less hollow than those of coelurosaurs, especially since the former is both a megalosauroid and a semi-aquatic. In short, the arguments made there are insufficient for supporting the enthusiastic claims.
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Fragillimus335
Member
Sauropod fanatic, and dinosaur specialist
Posts: 573
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Post by Fragillimus335 on Mar 12, 2014 3:30:34 GMT 5
I wouldn't doubt that at parity, Spinosaur necks were less robust and less resistant to damage than other theropods. But not by a drastic margin, as is often claimed.
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