Re: Feather Flap

[Michael Habib <mhabib5@jhmi.edu>]

> Having said that, there is the argument that the reason why 
> _Archaeopteryx_ and _Caudipteryx_ lack an "inner wing" is a 
> preservation artefact.  The argument runs that these festhers are less 
> likely to be preserved with the skeleton because the attachment is not 
> as strong, given that these proximal feathers have a lesser role in 
> thrust-generation.

I agree that there is a very real chance that the lack of tertiaries in 
Archaeopteryx, at least, is an artifact.  However, the feather 
attachment argument for it is very weak.  The attachment of tertiaries 
to the wing, while not quite as rooted at the bone as secondaries, 
should still be quite resistant.  Furthermore, while the inboard 
feathers have a lesser role in thrust production, they have a greater 
role in weight support, and thus still experience significant 
aerodynamic forces (though the inboard wing experiences minimal induced 
drag because it is distant from the tip vortex).

The more likely explanation, at least for Archaeopteryx, is that the 
tertiaries (if present) would likely have been lying right over the 
body of the animal at death in most of the better Archie specimens 
(based on humeral positions).  As such, they would be destroyed during 
preparation to uncover the skeleton of the specimen.  That how it 
appears to me, at least, but that is purely based on photograph 
observation.  I still think it's less of a punt than poor feather 
connection.  The specimen that might be a counter to this is the London 
Archaeopteryx, which has good feather preservation and one humeri not 
as tight to the body as in other specimens.  The feathers are a bit of 
a directional mess, though, so I can't tell what is going on there from 
photos alone (even good ones).

Cheers,

--Mike H.