Re: To Sprawl or Not to Sprawl?...

["Tim Williams" <twilliams_alpha@hotmail.com>]

DinoBoyGraphics@aol.com wrote:

> The morphology of the femora and pelvic girdle of the CAGS specimens of M. 
> zhaoianus clearly show that they were of the typical theropod 
> (non-sprawling) variety, so speculations about the hind "wings" flapping!  
> or being employed in a sub-horizontal manner need to be amended.

A few things to consider...

(1) The femoral morphology of _M. zhaoianus_ may not be the same as that of 
and _M. gui_.  The former appears to have the normal theropod-type femoral 
head (also retained in birds); but _M. gui_ may have a derived subspherical 
femoral head allowing a "sprawling" hindlimb posture.  (If this is the case, 
this would undoubtedly warrant generic separation for _M. gui_).

(2) A subspherical femoral head maybe functionally correlated with the 
presence of hindlimb wings, toward coplanar orientation of the fore- and 
hindwing surfaces 9e.g., for gliding).

These are working hypotheses that need to be tested based on examination of 
the actual specimens.  This will hopefully also resolve the taxonomic 
standing of _M. gui_ and _Cryptovolans pauli_ vis-a-vis _M. zhaoianus_.



Tim

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