Birds can fly— at least, most of them can. Flightless birds like penguins and ostriches have evolved lifestyles that don’t require flight. However, there’s a lot that scientists don’t know about how the wings and feathers of flightless birds differ from their airborne cousins. In a new study in the journal PNAS, scientists examined hundreds of birds in museum collections and discovered a suite of feather characteristics that all flying birds have in common. These “rules” provide clues as to how the dinosaur ancestors of modern birds first evolved the ability to fly, and which dinosaurs were capable of flight.
Not all dinosaurs evolved into birds, but all living birds are dinosaurs. Birds are members of the group of dinosaurs that survived when an asteroid hit the Earth 66 million years ago. Long before the asteroid hit, some of the members of a group of dinosaurs called Penneraptorans began to evolve feathers and the ability to fly.
Members of the Penneraptoran group began to develop feathers before they were able to fly; the original purpose of feathers might have been for insulation or to attract mates. For instance, Velocirpato r had feathers, but it couldn’t fly.