PerspectiveEvolution

How birds became birds

Science  01 Aug 2014:
Vol. 345, Issue 6196, pp. 508-509
DOI: 10.1126/science.1257633

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Summary

Birds evolved from dinosaurs, but how long did this evolutionary transition take? Twenty years ago, it was widely assumed that the first bird—Archaeopteryx, which lived in the Late Jurassic (see the photo)—evolved its feathers, wings, and ability to fly within just 10 million years or so. Since then, it has become clear that most of the 30 or more characteristics that distinguished the small, flying Archaeopteryx from ground-dwelling, carnivorous dinosaurs (theropods) emerged much earlier. On page 562 of this issue, Lee et al. (1) provide evidence for sustained miniaturization for 50 million years before Archaeopteryx evolved (see the graph).