Four-Winged Dinosaur Reveals Birds Lost Flight Before Becoming Modern Avians

One hundred and sixty million years ago, a four-winged creature moved through what is now northeastern China — not striving toward the sky, but retreating from it. New analysis of Anchiornis huxleyi, published in Communications Biology, reveals that this feathered dinosaur was not a proto-flier but a secondarily flightless animal, its ancestors having already mastered and then abandoned flight. In reading the fossil record of its molting patterns, scientists have found that the arc of evolution is not always a climb — sometimes it is a deliberate, or at least inevitable, descent.