Re: Microraptor did not sprawl!

["Jaime A. Headden" <qilongia@yahoo.com>]

Greg Paul (GSP1954@aol.com) wrote:

<... I have seen no femoral head that has the classic, transversly broad 
cylindrical femoral head typical of avetheropods, including most large
flightless dromaeosaurs. All sinornithosaur femoral heads are modified
from the typical pattern in a manner that would allow considerably larger
lateral play, although just how far is not certain.>

  Except in all "sinornithosaur" femora which are known, currently, or
verifiable. Any statements of fact about femora not currently available
for comparisons to the readership should remain private, or be published;
for instance, I currently possess photos of quite a number of privately
held "microraptors" that include postural variations as seen in
*Microraptor* and *Confuciusornis,* with a fairly well-biased posture
towards lyin on their sides. Virtually every single femur is preserved in
side view, or the proximal end is obliterated or impossible to determine,
as in NGMC 91 (Dave) and most of the fine details of bones in Yixian
theropods. C'est la Liaoning.

  I would also like to direct attention to fig. 27, B of Hwang, S.H.;
Norell, M.A.; Ji Q. & Gao K.-q. 2002. New specimens of *Microraptor
zhaoianus* (Theropoda: Dromaeosauridae) from northeastern China. _American
Museum Novitates_ 3381. This, as Tim Williams pointed out a few days ago,
shows a non-spherical caput, which is block-ended, has no deep channel
separating the caput from trochanteric crest, has a primitive lower,
anteriorly placed lesser trochanter than the crest of the greater
trochanter, and there is virtually NO femoral neck. The femoral head is,
essentially, cylindrical. As in *Archaeopteryx,* the lesser trochanter is
separated from the greater, is lower, and the caput is not elevated above
the trochanters (though it is not in neither *Sinornis* nor
*Confuciusornis* though each have a well-defined neck and semi-spherical
caput); unlike *Microraptor,* the caput of "Archie" is rounded and almost
triangular, as in the afore-named basal birds, without a medial
block-shaped (i.e., quadrangular) caput, and the channel between
trochanters and caput is considered absent. These features illustrate that
NEITHER *Microraptor* nor *Archaeopteryx* possessed a femur, as both Scott
Hartman and myself have said before, capable of elevating laterally
without dislocating the femur; the acetabulum, as shown in both _Dinosaurs
of the Air_ and Hwang et al. (see above) of *Microraptor* nor
*Archaeopteryx,* does not allow the femur to elevate this way.

  There are OTHER ways to allow the leg feathers to act as a flight
surface, including tucking the legs up as in birds, or extend the legs
straight out rearward, but this, too, would be prevented by the primitive
arrangement of trochanters and their muscular analogues (see Scott's posts
and John Hutchinson's papers of femoral and pelvic musuclar anatomy
evolution).

  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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