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Re: Sifaka and Chukar Behavior: Trees Down or Ground Up?



I wrote:

<<I would add an "alular" fluff at the leading edge of the first digit,
though it may have only covered it and not form an actual alula (which I
suspect is more the case)...>>

Jim Cunningham (jrccea@bellsouth.net) wrote:

<Why, Jaime?  Note that I have no objection whatever to the alula fluff,
but am curious about either the evidence or alternatively, the line of
reasoning for assuming its presence (or lack thereof).>

  My reasoning is thus:

  The fluff sticking out from the leading edge of the first digit, and
apparently from the ungual/penultimate phalangeal joint in the left manus
(not as well preserved in the right) of *M. gui* are preserved primarily
as several parallel rachis that are not in fact parallel to the digit. If
pennate, they would angle distally into the resistant air current is the
animal was airborne unless the wing were backswept. Flexion of the digit
would only enhance this. I cannot tell if the vanes were fully locking,
even in the high-res photo I have, but their relationship to the finger
would at once suggest they serve a less than aerodynamic function. They
may be dissarticulate from the digit, but the regularity of the feather
directions in the main wing would seem to attast against this. My initial
conclusion had been that these feathers were less pennate than were
others, or downy, but I cannot support this on the available evidence.

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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