If you go through the quests for Bismark and Ravana's Ex modes, the tales you're told are not completely unlike the tales of Nidhogg and Ratatoskr. So how did they go from ancient dragons to a sky whale and a beetleborg is likely how the Ananta's deity is the way she is.

Quote Originally Posted by Enla View Post
Given that most of the beast tribes have some Allagan influence or origin in ARR
It's not until HW you discover it, and then it's only the Ixali. What other beast tribes were affected by the Allag?
If anything, I'd say the one thing they all have in common is actually the Ascians, as they're the ones teaching everyone how to summon Primals.