The silhouettes I used were representative of what rig I felt they would fit.
Placodus looked vaguely like a marine iguana
Not really a reason to not include new things mate 
Allo’s rig is way to huge for Alio. Bary’s rig is far underutilized and I feel like it’d be a great fit.
Oxalaia isn’t in the game so it has no rarity 
As with most things in the game, realism is often pushed aside in favor of creative liberty. Thanks for giving it a read!