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Re: Feather Flap

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).


--Mike H.