Feathers play an important role in evolution. Originally providing insulation they eventually led to flight. The fossil discovery of the Sinosauropteryx, a four-winged dinosaur with primitive wings, has provided evidence that dinosaurs gradually developed wings with feathers, ultimately becoming the birds that we see today. Feathers are shaped asymmetrically for aerodynamic flight, and are also important in courtship displays.   The Pterosaurus, a prehistoric flying reptile, had hollow bones and large membrane covered wings. The Confuciusornis, a prehistoric bird with a toothless beak, was more similar to our birds. 

Birds continue to hone their flight abilities today: condors in the Andes can fly 6,000 meters above sea level; frigate birds can reach speeds of 400 km/h; snipes may fly non-stop for 5 days while migrating. Feathers were a very important innovation in the history of vertebrate life.