Analysis

(i) The standard view still appears to be that feathers evolved from reptilian scales. Christopher McGowan (1984:119) points out that one can see gradations from scales to feathers in the present world, often on the same bird, and that

feathers and scales are essentially just variations on a theme; both are formed of a horny protein called keratin, and they both develop along similar embryonic pathways. (McGowan 1984:120)

(ii) Prum and Brush (2002), who do not find the scale-to-feather transition plausible, have proposed a "developmental theory of the origin of feathers" that correlates earlier stages of feather development with evolutionary precursors of modern feathers. In their model, the earliest precursor of the feather is a simple feather follicle, an unbranched hollow tube; a series of progressively more complex intermediates (on two possible pathways) go all the way to the modern feather. Structures matching these precursors have been found in relatively new fossils.

References

McGowan C. 1984. In the Beginning...: A Scientist Shows Why the Creationists are Wrong. Buffalo: Prometheus.

Prum RO and Brush AH. 2002. The evolutionary origin and diversification of feathers. Quarterly Review of Biology 77(3).

Defender's Guide to Science and Creationism
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