Conversation so far:
what part of the chicken is the keel
A keel in bird anatomy is an extension of the sternum which runs axially along the midline of the sternum and extends outward, perpendicular to the plane of the ribs.
what purpose does the keel serve in a bird
The keel provides an anchor to which a bird's wing muscles attach, thereby providing adequate leverage for flight.

Question: is the structure different in flightless birds
Self-contained rewrite: is the keel different in flightless birds