What’s it about?
In modern bird, the primary flight feathers are asymmetrical. That is, if you compare the width of the feather on one side of the thick quill that goes the length of the feather with the width of the feather on the other side of the quill, they’re usually not the same. This asymmetry makes the feather capable of lift (like an airplane wing). This asymmetry is then interpreted to go hand-in-hand with birds being capable of flapping flight. From this, it is often thought that birds that lack asymmetrical feathers could not fly very well, if at all.
Why does it matter?
The authors show that with modern birds, the degree of asymmetry of feathers does not necessarily correlate with flight capability. From there, they state that scientists using the shape of feathers in the fossils of ancient and birds and dinosaurs to assume flight capabilities (or lack thereof) are likely incorrect.
Why did I read this?
This falls smartly in the category of ‘for fun’ reading. Feathers on dinosaurs and the origin of flight in birds are both hot topics these days.