Saturday, September 27, 2014

Birds Evolved From Dinosaurs Slowly—Then Took Off

An 80-million-year transition was capped with a burst of feathered diversity

Birds evolved from dinosaurs in patchwork fashion over tens of millions of years before finally taking to the skies some 150 million years ago, paleontologists report.

Birds are defined by a plethora of traits that are unique to them, such as feathers, hollow bones, a wishbone, and beaks. Paleontologists once supposed that the earliest bird, 150-million-year-old Archaeopteryx, represented a great evolutionary leap from dinosaurs. But over the past two decades, new discoveries have revealed that many of its avian traits had evolved in dinosaurs long before.
The Current Biology journal report released on Thursday confirms this new picture, finding that the dinosaur forebears of birds began gradually evolving avian traits almost as soon as dinosaurs appeared on Earth some 230 million years ago. (Related: Watch "Dinosaur Birds.")
The new study also supports a view proposed by the American Museum of Natural History paleontologist George Gaylord Simpson in 1944. He suggested that evolutionary novelty, flight in this case, can lead to rapid diversification among species exploiting new environmental niches.

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