When humans first came upon dragons. And yes, I'm being non-specific on purpose.
They can come form mouth nose or some dragons it comes out of tail or its spikes if it has any
No, only the true drags 'breath fire' and they are a small minority of all types of dragons.Not all of them, some come from the tall snow peaked mountains (there fire is totally un-useable). Dragons use a special crystal tooth near their throat to breath fire, in colder or wetter climates this is totally useless.
Dragons are said to have come a long time ago from another plane (see sites.google.com/mythology1000)
Worms do not come out in the sun because if they do come out in the sun, their skin will dry out. And if worms skin drys out they cannot breath and will die. The reason they would not be able to breath is because worms observe oxygen from the moist on their skin.
it may come from some dinosaur bones that were dug up and mistook for dragons
Come NOW
they were chickens in the first place but then the turned into dinosours then dragons
1999
1997
Where did the dragons come from in revelations
The random dragons come in different kinds, depending on your level. The first ones are just called 'Dragon', after that are Blood Dragons, then Frost Dragons, Elder Dragons, then Ancient Dragons. Some dragons have names, these dragons will be one of the types mentioned above.
Seals can't breath underwater, so they have to come to the surface for air.
probably people or dragons.