User blog comment:Zombiejiger/Showa Godzilla: Final Wars/@comment-3364111-20130922035804

Funny thing, Gorosaurus originally was set to appear in final wars, but was replaced by Zilla. same goes for Gotengo and Kaiser Ghidorah replacing Kiryu and King Ghidorah respectively. Looks it up in the japanese wikipedia enter on Final Wars:

http://ja.wikipedia.org/wiki/%E3%82%B4%E3%82%B8%E3%83%A9_FINAL_WARS