Actually she'd have to be a lot older than that I think. I'm not sure how specific the dialogue is, but I always took it that Ultimecia existed at least 100 years after the game's main events, I can't actually remember why though.
It was generally taken (at least by me), that Sorceresses either had longer lifespans than normal, or could sustain themselves magically. Evidence for this being the fact that Edea doesn't look nearly as old as she should, and arguably neither does Adel. Ultimecia in particular has a special relationship with time, though I can't remember exactly what it was, so I can't really back much up with that. I think the story of Hyne also might point towards such survival capabilities, but again, I've forgotten it.
Anyway, I don't know exactly what Ultimania says, but it seems to discredit at least a lot of the above speculation.
EDIT: DfKimera, the quote Sir Bahamut posted is from the Japanese version I believe. If I remember correctly then in one of the versions you get something similar through 'Scan'.




), that Sorceresses either had longer lifespans than normal, or could sustain themselves magically. Evidence for this being the fact that Edea doesn't look nearly as old as she should, and arguably neither does Adel. Ultimecia in particular has a special relationship with time, though I can't remember exactly what it was, so I can't really back much up with that. I think the story of Hyne also might point towards such survival capabilities, but again, I've forgotten it.
