Dragons have been common to many cultures and mythologies. Some famous are St. George slaying a dragon and Chinese dragons, such as the symbol used for the Emperor of China.
Creationists and Bible literalists do assert that dragons existed and that they are basically special dinosaurs.
Dragons are reptillian or snake-like creatures that share many characteristics with dinosaurs and may well be the same creatures.
http://conservapedia.com/Dragons
Consider the many dragon legends. Most ancient cultures have stories or artwork of dragons that strongly resemble dinosaurs.
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The simplest and most obvious explanation for so many common descriptions of dragons from around the world is that man once knew the dinosaurs.
http://www.creationscience.com/onlinebook/FAQ27.html
Has physical evidence ever been found that a dragon existed?