Re: Cost in Aquatic Birds (long)

["James R. Cunningham" <jrccea@bellsouth.net>]

I'm curious and have a question about the old thread that postulated flight
origins in the water (I don't know if that was the progenitor of this thread,
but it was convenient to post by hitting the reply button on this message).
Sorry if I'm off-thread.  For those who postulated that archie was an aquatic
swimmer, have you considered the following?  For reasonable thrust efficiency,
underwater 'flying' requires substantially more pronation during the downstroke
than flight in air (because the body weight doesn't have to be supported in the
water).  If archie were a swimmer, there should probably have been substantial
adaptations for increased pronation-supination ability at the shoulder, to the
extent that it should be observable in the fossil record.  This should require
either an advanced supra-coracoideus (sp?) or an equivalent mechanism.  I know
the s-c isn't advanced.  Are the equivalent modifications present?  If not, it
might imply that archie wasn't much of a swimmer, if at all.

All the best,
JimC

Williams, Tim wrote: snipped

> Jaime Headden wrote: snipped
>