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Re: Parahongshanornis, new Chinese Cretaceous bird (free pdf)



Mickey Mortimer <mickey_mortimer111@msn.com> wrote:


>Agreed on point b, but II-2 being longer than II-1 is just a symplesiomorphy.


>From an ecomorphological perspective, the retention of
symplesiomorphic characters can often be quite significant.  Although
I concur that, in the case of _Patagopteryx_, too much significance
shouldn't be invested in this character.


> It would certainly be an interesting study, with Patagopteryx's combination 
> of primitive and derived features.  However, note that the second digit is 
> much smaller than Caudipteryx, about equal to
> metacarpus length instead of over twice as long.  Similarly, the ungual is 
> more poorly developed.  Perhaps most damning is that the first digit seems to 
> be absent, since there is a keel where it would
> normally be placed.


Yes, the manus of _Patagopteryx_ is obviously poorly adapted for
grasping (even two-handed grasping).  Nevertheless, relative to the
hindlimb, the forelimb of _Patagopteryx_ is twice the length of the
forelimb of _Caudipteryx_ (humerus+radius/femur+tibia: ~80% vs 40%).
I know this isn't an ideal comparison, given that the hindlimbs of
_Patagopteryx_ are more robust and less cursorial than the long,
gracile hindlimbs of _Caudipteryx_.  But for a flightless bird such as
_Patagopteryx_, the forelimbs were not reduced by all that much.
Either _Patagopteryx_ represents a recent transition to flightlessness
(in which case the forelimbs are still in the early stages of
truncation), or there was selection against extreme forelimb reduction
(such as not to sacrifice reach).



Cheers

Tim