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Re: Concavenator has two humps



I'd be very careful about jumping to conclusion about a "sail". The
tail has higher neural arches than the back (but for the hump) - but
given the fat tails of dinosaurs (yours, dear Greg, are always too
thin, see, e.g., Persons's wonderful talk in Bristol) these high
caudal neural arches may simply be related to the tail musculature,
and not to any showy of other structure. So there may have been a
sail, or there may not.

If there was one extraordinarily high caudal spine - the way the
dorsal one sticks out -, then one could reasonably assume that a sail
was stretched between them. But as things are any sail talk is very
speculative, and extending that to a generalization about dinosaur
sails is bad practice.

Best
HM

On Thu, Sep 9, 2010 at 2:53 AM,  <GSP1954@aol.com> wrote:
> Both the text and the life illustration of Concavenator show a single hump
> just before the hips. But the tail base neural spines are also elongated
> while those over the pelvis were apparently not, so there are two humps (there
> may be a less extreme hip dip in Ouranosaurus). The arrangement tends to
> favor that dinosaur sails were for display rather than supporting fat deposits
> in at least some cases.
>
> Hopefully this example will establish that the presence of scales on a
> dinosaur specimen does not exclude the presence of feathers elsewhere on the
> animal. And with bristles etc showing up hither and yon in the group it is
> highly plausible that feathers go way back into basal theropods - as per the 
> old
> Sarah Landry feathered Coelophysis (=Syntarsus) in Bakker's 75 Sci Amer
> article.
>
> GSPaul</HTML>
>