PerspectiveEvolution

Beyond the rainbow

Science  24 Oct 2014:
Vol. 346, Issue 6208, pp. 416-418
DOI: 10.1126/science.1258957

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Summary

Once believed to be a diagnostic feature of birds, feathers are now known to have evolved in dinosaurs well before the first birds. In birds, feathers serve several functions: Down feathers insulate the body, whereas planar or pennaceous feathers are necessary for flight, communication, camouflage, and brooding (see the first figure). What was their original function in nonavian dinosaurs? Based on a specimen of Archaeopteryx that preserves a spectacular plumage of pennaceous feathers, Foth et al. (1) recently hypothesized that pennaceous feathers did not evolve for flight but for display. Together with insights into body size evolution in dinosaurs along the line to birds (2) and the discovery of protofeathers in early dinosaurs (3), these results contribute to an emerging understanding of why pennaceous feathers may have been superior to filamentous protofeathers.