User blog comment:Mckrongs/Monster Hunter 4 for the Nintendo 3DS/@comment-4775842-20120803125321

I personally believe we should've had 'both' Pelagus and Primatius as seperate monster groups. The first pelagus such as bulldrome and blangonga were quite obviously mammalian. But some of the new pelagi such as Aoshira are more difficult to classify. Aoshira is almost an inbetweener. So, I think that Primatius should be brought back to classify the obviously mammalian monsters (Blangonga, Rajang, Bulldrome, Congalala, and even the new Kecha Wacha) and use the pelagus group to classify the monsters that are somewhere in between the evolutionary groups of reptile and mammal (Aoshira, Rangurotora, etc.)

Hopefully they'll make the change in MH4.