It might not be immediately obvious just how birds could evolve something as complex as the wings needed for flight. But that's just it: flight was basically incidental to the real adaptation. The secret is a little something called flap-running.

All winged insects look more or less the same: a main thorax that's split into three segments, two legs on each segment, and four wings. But there's one exception, and it's spectacularly weird. Meet the massive "helmets" of treehopper insects.

Or so said Dr. Lucien Bull of the Marie Institute at Paris, as cited in this 1929 issue of Modern Mechanics. And you know what? I'm with him. I don't know about you, but I wouldn't mind living in Hawkworld. [Spotted on Modern Mechanix]