Flight feathers are extraordinarily detailed in construction and strong for their weight. The upstroke of the wing forces the feather's vanes to open like Venetian blinds. This effect lets the air pass through and offers little resistance. The downstroke is the power stroke - the feathers twist back into a flat wing surface, and move the bird through the air. Not only do the individual parts of birds appear to be designed, but the bird itself is a synergistic whole, created for the purpose of flight.
Conclusions There are arguments that birds evolved from dinosaurs, but there is no evidence.
What was thought to be an intermediate, Archaeopteryx , was really a true bird that lived at the same time as the dinosaurs and other true birds. The evidence that does exist demonstrates birds did not evolve from dinosaurs. There are arguments that birds evolved, but no evidence. The evidence that does exist demonstrates that birds did not evolve. The oldest known fossil birds are those of true birds.