User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-7584137-20131024180456/@comment-17735225-20131026034605

I don't think I can find any plausible explaination of this monster from in-game info yet, but this is my speculation on the concept of this monster.

Frontier dev team think they should mash up all the monster of one type and create the ultimate monster for player. This time they choose flying wyvern ('true' flying wyvern as dubbed by some fans). This time they don't take their effort to design a new monster and decide that they should use the altered appearance of the old monster. Rath couple come to their mind because they're the first and iconic of their type. So now they fused both characteristic of the two (Los' wing, Ian's hair, etc.) and now unknown was born.

It has been made unknown probably because of the above concept, it doesn't make sense in any evolutionary line much (except dubbing it the prime ancestor of all the flying wyvern, but then it wouldn't make sense why they would evolve to be weaker, they don't possess any disadvantage from current ecosystem, maybe they require a lot of food to survive?). So letting people create theory for this monster themselves seems to be a better idea overall.

Same could be said for Mi Ru.