The old paradigm of bird evolution is admittedly flawed, according to writers of an article in Scientific American. The authors admit that evolution does not provide a valid mechanism for creating the amazingly strong, yet lightweight, structures found in birds but not in their close dinosaur cousins. Archaeopteryx is discounted as shedding no light on the subject since its feathers look just like modern feathers. There is no fossil evidence of the transition from simple reptilian scales to complex feathers with their many interlock parts. Evolution cannot explain why feathers would have developed from scales for flight and then developed a new developmental pathway to form them. To explain this, the authors suggest that feathers evolved before theropod dinosaurs or birds. There is no fossil evidence to support this claim and the possible reasons for the development of feathers includes camouflage, insulation, protection and other hypotheses that are not supported by the fossil evidence.
Challenging evolution is not an option, so the evidence just gets reevaluated. The new mode of interpretation is called evolutionary development biology for short. According to this, "the complex mechanisms by which an individual organism grows to its full size and form can provide a window into the evolution of a species' anatomy." In other words, by looking at the stages of feather development in a bird today, we can look for "ancient" dinosaur feathers at the early stages of development. The new concept is based on many assumptions that limit its scientific validity, but it has become popular nonetheless. Challenges to the idea of dino-to-bird evolution continue to plague the proposal and leading evolutionary biologists can't even agree on the big picture, let alone the details.
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