Thread:Knj00/@comment-7149557-20130331175140/@comment-4830404-20130331180532

No. The dragon that you get is decided the moment that you put it into the den.

In some extremely rare, confusing cases listed on the Glitches page, the game messes up and you get a completely different egg than the timer suggests. That is due to the game having an error somewhere and I haven't heard a report of it for months.

Speeding up the dragon with gold will NOT give you anything rarer. That functionality is not built into the game.