Many people believe that the origination of dragons came from serpents. Rather, they came from snakes and eels that people saw. As time went on and art evolved, these serpents became more and more decorated until they looked more like semi-Chinese dragons or sea serpents.
It is also suggested that people saw mutated eels and snakes or thought that some of their surroundings (i.e. for eels, seaweed, for snakes, sticks) were actually a part of them. Thus making them look as if they were draconic. This actually suggest that dragons were formed out of the misinterpretation of artwork, stories, and sights throughout the ages.
This theory pertains to the remains that people found and called "dragon bones" so it definitely holds no water in battle of where the term dragon came from. However, it does provided an interesting idea that people thought the bones of dinosaurs to be dragons, and they though dragons to be descendants (or parents) to such serpents as the snake and lizard. The Bones Theory suggests that people found the bones and created stories about the fierce creatures that once lived within those bones.
Sadly, this theory is lacking when it comes to civilizations as China and other Asian dragons. Due to their unscientific structures, Chinese dragons and Asian dragons could never have originated from seeing bones. On the other hand, one might think that they either adapted the bones to the dragons or they only found some bones. Whichever the case, this theory is not as likely as the Serpent Theory.