Keyword: birs

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  • Prehistoric Birds May Have Used Four Wings To Fly

    03/14/2013 6:43:48 PM PDT · by Dysart · 50 replies
    Smithsonian ^ | 3-14-13
    Roughly 150 million years ago, birds began to evolve. The winged creatures we see in the skies today descended from a group of dinosaurs called theropods, which included tyrannosaurs, during a 54-million-year chunk of time known as the Jurassic period. Why the ability to fly evolved in some species is a difficult question to answer, but scientists agree that wings came to be because they must have been useful: they might have helped land-based animals leap into the air, or helped gliding creatures who flapped their arms produce thrust. As researchers continue to probe the origin of flight, studies of...