Board Thread:MHX General Discussion/@comment-25706585-20151203134449/@comment-5167887-20151203135837

Let's say Dino and Tama are the "wyvernest" of the four. Wyverns are usually weak to dragon. Raizex is for sure a wyvern but it has some insect parts in its design -and insect monsters in MH are usually resistant to dragon-, and Gamuto is just a fanged beast.

That's how it can be explain IMO.