[kosta50]

Wikipedia is a good start (but don't put too much trust in it), as a general overview and for external links. New Advent may be of greater help. Medieval documents sites could provide actual manuscripts. I have not seen any. I do know that the order of prayers was reversed (beginning to end) and some prayers have been added or removed. Specifically, the epiclesis does not appear in the TLM, not as far as invocation of the Holy Spirit, but rather in a round about way only mentioning "God."

Novus Ordo Mass returned some of the more ancient elements to the Mass, such as the sign of peace (still practiced in Antiochan Orthodox Churches), and epiclesis, calling on the Holy Spirit, as is done in all Orthodox Churches.

[maryz]

such as the sign of peace (still practiced in Antiochan Orthodox Churches)

Well, it was there, if in somewhat truncated form (Pax Domini sit semper vobiscum).

Somehow I can't picture the Antiochan Orthodox going for the free-for-all bonhomie of the NO sign of peace! (If they do, please don't disillusion me!)

Thanks for the starting hints. I know the Sarum is the earliest surviving English liturgy, but the mss. only date to the 12th century, so that doesn't get me very far!