Feathers

Alan Feduccia, a world authority on birds at the University of North Carolina at Chapel Hill and an evolutionist himself, says "feathers are a near-perfect adaptation for flight" because they are lightweight, strong, aerodynamically shaped, and have an intricate structure of barbs and hooks. This structure makes them waterproof, and a quick preen with the bill will cause flattened feathers to snap into fully aerodynamic shape again.9

Some evolutionists claim that feathers evolved from scales, but scales are folds in skin. Feathers, on the other hand, are complex structures with barbs, barbules, and hooks. Feathers also originate in a totally different way, from follicles inside the skin in a manner akin to hair. Finally, feather proteins (φ-keratins) are biochemically different from skin and scale proteins (α-keratins) as well.

Special flow-through lung

Bird lungs are very different from reptile lungs. A reptile lung is like a bellows, that is, air is breathed in, and blood takes up the oxygen and releases carbon dioxide. The stale air is then breathed out the same way it came in.

However, birds have a complicated system of air sacs that makes use of even the hollow bones. This system keeps air flowing in one direction through special tubes (parabronchi,singular parabronchus) in the lung, and blood moves through the lung's blood vessels in the opposite direction for efficient oxygen uptake,10 an excellent engineering design.11

How would the "bellows" style of lungs of reptiles evolve gradually into avian lungs? The hypothetical intermediate stages could not conceivably function properly, meaning the poor animal would be unable to breathe. One of the first developmental stages would be a poor creature with a diaphragmatic hernia (hole in the diaphragm), and natural selection would work against this. Lung experts who studied the incredibly well preserved fossil of Sinosauropteryx (an alleged evolutionary ancestor of birds) argued that "its bellows-like lungs could not have evolved into high performance lungs of modern birds."12

Could Bird Flight Have Evolved?

There are two main theories for the origin of flying birds: (1) that birds evolved "ground up" from running dinosaurs (the cursorial theory) and (2) that they evolved "trees-down" from small reptiles (the arboreal theory). Both sides produce devastating arguments against the other side. The evidence indicates that the critics are both right—birds did not evolve either from running dinos or from tree-living mini-crocodiles. Yet, whenever one or the other theory is proposed, the popular press fosters the impression that this new "evidence" mounts a cumulative case for bird evolution, when in reality this new evidence cancels out at least one of the theories.

Furthermore, many of the arguments don't understand what flight involves. For example, the skeptic-dominated Australian Museum asserted that certain dinosaurs evolved a certain bone that "also allowed them to move their hands in a broad fan-shaped motion and to snap their long arms and grasping fingers forward to grab fleeing prey. This powerful, flapping motion has today become an important part of the flight stroke in modern birds."13

However, this would be just the wrong sort of motion for flight. A flap in the forward direction would have the effect of pushing the bird backward. Also, feathers are not the sorts of structures that would be useful on limbs that flap at a prey animal, since the prey would be damaged by their pounding.

Finally, the purpose of the wings is to force air backward and downward so that the bird is propelled forward and kept aloft. Therefore, wings must form a wide surface that has high air resistance, so that they can move large volumes of air. But for a limb designed to grab forward at prey, it's an advantage to have a surface that has low air resistance, i.e. lets air through easily. Picture, for example, the holes in a fly swatter or streamlined shapes designed to move through the air as opposed to moving the air itself. Also, the rush of air from the proto-wing would warn the prey of its impending doom!