The ability of birds to fly is faciliated by their _________.

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    four-chambered heart
    hollow bones
    lungs supplemented by air sacs
    external development in a shelled egg
    All of these are correct.

asked May 30, 2013 in Biology by anonymous

1 Answer

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All of these are correct.
answered May 31, 2013 by Bioshare ~Top Expert~ (34,070 points)

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