RE: Swiming spinosaurus

["BJ Strata" <bjstrata@hotmail.com>]

Gunter Van Acker wrote (concerning the sails of Spinosaurus, Rebbachisaurus
and Ouranosaurus:

> The sail could have had 2 possible functions :
>
> 1. display; either to make the animal more attractive to the opposite >sex,
> or to make it look more menacing and larger when confronted with a
> competitor
>
> 2. Since the unrelated Spinosaurus, Rebbachisaurus and Ouranosaurus all
> >seem to have had a dorsal sail, and they all had different behaviour (a
> >carnivore and 2 herbivores with different feeding strategies), it's
> >possible that the evolution of a sail-like structure was triggered as >an
> adaptation to an unusual environment. The mid-Cretaceous North >Africa may
> have known long seasons when food was scarce (e.g. few >plants because of
> drought, which forced herbivores to migrate), and >the "sail" was actually
> more a sort of "hump" where fat was stored when >food was abundant. This
> theory has been forwarded before.

While I had previously considered heat-regulation as the reason for
convergent sails in these three VERY distantly related dinosaurs, this
second theory is quite appealing.  I would dismiss the first theory, as it
seems highly improbable that such distantly related animals would evolve
such similar sexual "lures."  However, the second theory "just feels right,"
as one of the list members so eloquently put it (I apologize that I forget
whom waxed eloquent :-).  How do the neural spines in these dinosaurs
compare with extant mammls with such "neural fat stores," such as camels,
bison, and...I can't think of any others (I know horses have tall "withers,"
but I don't know of fat stores).

BTW - Gunter said "this theory has been forwarded before."  Anywhere in
print?

As always, continually ranting,
BJ Strata
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