Crawford labels this quadruped as a ram. Not a great fit. Hersh thought differently:
I hate to disagree with Hersh, but I don’t think that’s an udder hanging down. I think it really must be a calf, a male calf. I submit as evidence specimens of RRC 526:
Can we by extension guess that moneyer might be a Vitulus?! Or perhaps its too early for such punning symbolism. The main family to use the cognomen in the 3rd century were the Mamilii, namely the consuls of 265 and 262 BC.
Of course bulls and bull calves and Italian identity go together more generally (Pobjoy 2000: 201):
But then again it could just be just another symbol to distinguish the series. Something vaguely thematically appropriate (abundance, sacrifice …) but of no special significance.