Re: The Men Who Stare At New Papers

[David Marjanovic <david.marjanovic@gmx.at>]

> > In the evolution of flight in theropods, the key word is
> > "exaptation".  Many flight-related features that we see in birds
> > likely evolved originally for other purposes, such as the furcula
> > ("wishbone"), long forelimbs, pneumatic bones, enlarged breastbone
> > (sternum), and of course feathers.  All these features came to be
> > incorporated into the avian flight apparatus (probably in a
> > stepwise fashion), but they probably didn't begin that way.
>
>  I thought flight (gliding or powered) came before the enlarged
>  breastbone, and that primitive birds (which clearly could at least
>  glide) didn't have them?

That's another level of "enlarged". :-)

> > For example, are these features perhaps correlated
> > with reinforcing feather attachment?

Yes, of course.

One obvious activity that requires firmly attached feathers is flight. 
But there are others (WAIR, stability flapping...).

> > It was once assumed that the presence of
> > quill nodes along the ulna was an exclusively flight-related
> > character - until they turned up in _Velociraptor_.
>
>  Unless, of course, Velociraptor had flying/gliding ancestors / was
>  secondarily flightless, which appears likely.

Do any extant flightless birds have quill knobs? I think not...