Three origins for flight in birds are discussed in terms of adaptive scenar
ios. The discovery of feathered but flightless dinosaurs in China suggests
that many of the adaptations in birds, currently considered as components o
f flight, might better be considered as requirements for the success of fea
thers and the development of feathers may well have been a more important e
vent in bird evolution than the development of flight. The existence of an
array of potential ancestors with feathers and the success of large groups
of birds without volant representatives suggest that flight might have evol
ved more than once.