Just had another look through my photos and I think this must be Shani, she does look slightly older.
Actually yes this one's head is quite rounded more like a young animal - I failed to spot that. I thought at first this was an older animal displaying the sagging lower lip that is sometimes seen in older primates. But thinking about that Shani at 20 years old probably wouldn't be old enough for that anyway. The mouth looks like that because she's eating and there is a piece of food in her hand.