This is an idea that grew out of my last post which spiraled into tessera hospitalis, tokens of friendship. It makes good sense that we have ones in the shape of joined hands. The dextrarum iunctio was a common symbol of concordia and fides. But what is up with all the half animals? I think that it is likely to represent the animal sacrificed in the creation of the union. I would also hypothesize that pigs are popular in this private domestic context for the same reason that we see pigs being used to seal a foedus.
Allow me to remind you of some famous numismatic pigs:
The coin above is just there as a reminder that boars do appear on early Roman coinage in other contexts. The main point of this post is put up this curious theory about the elephant and pig currency bar (RRC 9/1):
Taken from p.462 of Borba Florenzano, Maria Beatriz ‘Aes signatum bars, signa and coins: emblematic objects and apotropaism’ from XII. lnternationaler Nurnismatischer Kongress, Berlin 1997 (2000), 460-465.
I would just note in comparing the boar above to our friend the sow below, that both are represented with an impressive line of bristles down their backs. I do think, however, the two engravers have carved the animals in such away as to plainly distinguish their genders. And, I have my doubts that the legions would use the female, instead of the male, as their totemic creature…