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Re: The Men Who Stare At New Papers

> 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...