I was reading Crawford and he said that there was no convincing proposal of which A. Postumius Cos the portrait meant to honor. I grant there are seven men who held the consulship with this name (DPRR link to search results).
BUT I’m strongly inclined to think the man who made the coin is honoring his v own adoptive father the consul of 99.
The ancestry is deduced from Cicero’s letters, reading Cic. Att. 5.21.9 with Cic. Att. XII 22.2. Shackleton Bailey in his commentary endorses this reading and others have followed.
If correct this would also throw out Crawford’s speculation that his adoptive father was the moneyer of RRC 372.
The consul of 99 was killed in a mutiny in 89 in the social war, but even ancestors with greater failures had been celebrated on the coins…. Cf. this early post.
Update the next day: A colleague points out via twitter that it would be a very early adoption in an old family. A valid concern, I wonder if any one has done a typical age at adoption study for the Roman elite? How deep is the data to do such a study? This question generated some twitter convo of its own.
The same colleague points out that the consul of 99 also was ‘trounced’ (great word!) by Jugurtha.