other types of vessels than amphorae (possibly unrecognised by archaeologists) – not to speak of wooden crates, baskets or other containers of perishable materials – might have been involved in such a trade.
A possibility of further research and another paper. The topic the author discusses is quite specific and, at large, seemingly inconsequential if they did not mention the importance of these various other vessels until now. Though, they mention there is a lack of evidence regarding these vessels as many might have just been destroyed, undocumented, or otherwise.