User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-3339774-20111220000609/@comment-5020152-20120727182044

My theory is that Ancient Rathian is a monster from ancient times that has only recently awoken. That could explain why there aren't very many. As for the new attacks, it's possible that it knows special skills that, over time, were forgotten by modern Rathians. ... How's that sound?