Re: Pro(to)avis

[Michael Habib <mhabib5@jhmi.edu>]

> > 2) The hindlimb feathers may have more important to increasing 
> > passive stability than to generating lift.
>
> To be passively stabilizing with anhedral, the hindlimb feathers would 
> need to be creating a download rather than upwardly directed lift.  
> Some aircraft do that, but I doubt that an animal would deliberately 
> create a substantial download for any extended period of time.

Good point.  I doubt that as well.  I was just throwing out ideas, but 
it doesn't strike me as particularly likely now that you mention it.

> Creating lift with the hindlimbs either lifting or downloading in a 
> subhorizontal orientation would do this anyway, due to the increase in 
> induced drag as the hindlimb aspect ratio decreases.

Which reminds me...

1) What sort of shape is currently being ascribed to the hindlimb 
airfoils where present?

2) Is there any osteological evidence in those specimens with hindlimb 
airfoils for anchoring of the lengthened feathers (similar to the 
anchoring points on the posterior ulna in most birds)?

Cheers,
--Mike Habib