I was thinking about social classes too, after posting that post of mine. I think it would work well if you'd assign multiple classes to one critter. This way, you wouldn't have to put same emotes into many classes. You've probably thought it like that too, as I see generic in your list.

Examples:

A lion(as well as cat, panther, jaguar, tiger, lynx and bobcat(the latter two didn't have very long tail IIRC, so tail might need to be removed from the list when they are concerned)) could get classes:

Generic(basic socials for all forms)
Mammal(socials common to all mammals)
Tail(socials that include having tail)
Cat(feline socials)

A spider monkey could get classes:

Generic
Mammal
Tail
Primate(socials including hands, apish gestures not containing facial gestures)
face(socials containing facial gestures)

If we drop tail from the list, we get socials for orangutan, dropping face from list gives socials for sifaka lemur.

That kind of stuff. I was just playing with the thought some ;P