Re: The origin of flight: from the water up (still short!)

["David Marjanovic" <david.marjanovic@gmx.at>]

> Oh.  What aerodynamic properties does a large wingspan relative to trunk
> length specify?  Are you saying that R was a spanloader?

Probably not, as I don't know what a spanloader is. :-) -- Basically I'm
just naïvely saying that *R.* was able to fly at all, and that *Caudipteryx*
was not. When the wings are below a certain relative size, flight is
impossible. *Rahonavis* has longer wings than both *Archaeopteryx* and
*Confuciusornis* in relation to both trunk length and hindlimb length (just
checked from illustrations); in the latter 2 the tibia is the longest bone
in the body (the plesiomorphy), while in *R.* the ulna is longest (it is 150
% femur length while the tibia is 137 % femur length, according to the
description), even though the tibia is relatively longer than in the other
two animals.

BTW, I think FUCHSIA may be able to explain the short tails of Pygostylia,
"enigmosaurs" and basal "dromaeosaurs" incl. Archie, as well as the
pygostyle:
    - If the tail with its long rectrices was used for steering in Archie,
it would have been rather difficult to move if it would have been longer.
Secondarily whatever-less "dromaeosaurs", oviraptorids and others all
independently lengthened their tails independently -- *Microraptor* has a
short tail, dromaeosaurids have twice as long ones and look more similar to
basal coelurosaurs; *Caudipteryx* must be careful not to fall on its few
teeth, *Oviraptor* is better balanced.
    - The pygostyle is widely thought to provide stronger anchorage to the
tail feathers, so it may well have brought an advantage here, too. A tail
that is mobile throughout its length (except the pygostyle), as seen in
"Enigmosauria" and Pygostylia, should influence manoeuverability, though I'm
not exactly sure how; but such things are testable. :-)
        (I can suggest a probably cheap way to do it: Take a cormorant, or
another diving bird that steers underwater with its stiff tail feathers,
glue an artificial Archie tail on it -- Superglue will hold to the next
molt, it's terrific on keratin --, set the poor bird free, and see what
happens. ;-) )