“A number of them were developed while at least +John was alive.”
Which ones?
“Which ones?”
Probably the West Syriac ones, at least some of them. The Didache speaks of them. I think its likely that the anaphora used by the Maronites might be one, or at least very close. The one we use on most Sundays is from the 4th/5th century, but is taken from the West Syriac ones so would be recognizable if not exactly the same wording. This isn’t as remarkable as you might think. If I were to attend a Maronite Liturgy, or a Roman Catholic Mass or a High Church Anglican Liturgy, or the Liturgies of ++ Mark or James, I’d recognize their anaphorae immediately despite the fact that they are all different from the ones I hear. They all come from the same sources.