百科全书中的解释：
http://en.wikipedia.org/wiki/Wyvern
A wyvern (or wivern) is a winged reptilian legendary creature often found in medieval heraldry. Its usual blazon is statant (standing). The wyvern is similar to a European dragon, but it differs in that it has only two legs (thus making it rather bird-like), cannot breathe fire, and has a barbed or snake-like tail. Occasionally, it is said to be smaller than a dragon or to be able to breathe fire. The wyvern is similar to another mythical creature, the cockatrice, which is similar to the basilisk. Its sounds are similar to the tone of a whistle or flute.
Variants of the wyvern include the sea-wyvern, which has a fish-like tail. Of the dragon-like creatures, wyverns are said to be the most feline, having a cat-like intelligence and temperament. During the Middle Ages, they were supposedly the most useful of all dragons to sorcerers, as they had the unique ability to work easily with spells.
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http://en.wikipedia.org/wiki/dragon
A dragon is typically depicted as a large and powerful serpent or other reptile, with magical or spiritual qualities. Mythological creatures possessing some or most of the characteristics typically associated with dragons are common throughout the world's cultures.
