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



David Marjanovic (david.marjanovic@gmx.at) wrote:

<Need not impair the claw, IMHO. The claw is still quite large, unlike in,
say, the coeval *Sinornis*.>

  The point was that feathers attach or overlap the non-ungual phalanx.
The claw is irrelevant, and I wasn't using it.

<The 3rd finger is under the wing and free, best seen in *Confuciusornis*,
but also in all those specimens, e. g. of *Archaeopteryx*, with crossed
fingers. Fits Dial's observation that the base of the 3rd metacarpal is
ventral respectively medial to the 2nd, rather than lateral respectively
caudal.>

  I was talking about metacarpals. In modern birds as in some early birds
like *Jeholornis*, the third digit is proximally bowed and expanded
laterally, providing a structure basis against distortion, likely as a
result of the overlaying feathers on the proximal second finger phalanges.
However, in reference to the metacarpals, outward bowing, however the
unmentioned fingers were, would imply the third digit could have been
constrained by integument.

  Also on this thread, I mentioned an alula for *Microraptor* (as in the
new paper) as well as NGMC 91, which Luc Bailly may have misinterpreted
when he pointed out images of the alula. I was hoping not to be
misunderstood, but my fault for my phrasing. I did in fact mean to say
that both *Microraptor* and NGMC 91 have alular like tufts of feathers on
the first, bowed phalanx of digit 1. This is unlike the later birds which
have a distinct pennate alular structure, and unlike *Archaeopteryx* which
appears to lack an alula altogether. There was either a loss of the
structure in *Archaeopteryx* from the "more advanced fliers" at the base
of the dromie radiation (Greg Paul's view) or there were two convergent
developments of a leading foil alular structure, one pennate and one
apparently not despite the presence of pennate primaries and secondaries.
*Caudipteryx*, a basal oviraptorosaur with incipient wings, and contra
Paul's hypothesis, lacks an alula, and would seem to disprove its
secondary flightlessness inately. In fact, I would offer the realtively
short, thick-legged Caudi as a parallel to Dial's chukar partridges,
rather than the long-legged, slender-limbed and seemingly scansorial
dromaeosaur or dromie-like theropods.

  Cheers,

> 
> The femoral head of the holotype of *Sinornithosaurus*, drawn in the
> Nature
> paper from 1999, is :-o suggestive of sprawling capability, along with
> the
> mentioning of an "open acetabulum tending to close off medially". But
> are
> there any good illustrations available? The Nature photos of *M. gui*
> have
> much too low resolution to even discern the femoral heads from the
> pelvis.
> :-(
> 
> 
> 


=====
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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