I was doing some math...
Funnily enough, Garp and Roger were almost the same age, but by the time Roger became father (unless some other forsaken or hidden chield shows up), Garp was almost grandfather, but we already knew this, kinda offtopic. With this chapter, though, we find out:
Garp is 78. Dragon is 55. Garp had Dragon when he was 23 or something like that.
If i'm not mistaken, when the battle against Rocks took place, Dragon was already 17 years old... Same age Luffy had when he began his journey.
Dragon must have seen a lot from way back then, including his father defending (even though probably not liking it) the Tenryubito...
Dunno.. just some food for thought. What do you guys think?