Tridentine Mass 90%+ same as Roman Rite a century earlier

According to Luc Perrin*, writing in the ctngreg yahoo group:

"Tridentine" is conveying the false idea, used by pope Paul VI in his 1969 constitution promulgating NOM, that council of Trent = Tridentine liturgy, Vatican II = Novus Ordo, so everything's fine. When it is neither fine nor correct, historically speaking. The Pian missal is in no way a complete reshaping of the previous Roman liturgy, but is reprinting over 90% of a missal edited one century ago, adding the "rubrics".

Allen Maynard adds:
The Ordinary of the 1570 Missal was identical to that of 1474 and differed very little from the 8th century versions.

If you don't have one, get a copy of Michael Davies' wonderful little booklet "A Short History of the Roman Mass" - it is an indispensible 'primer' on the highlights of Western liturgical development. The text is available online at: http://www.latin-mass-society.org/msshst1.htm.

Luc Perrin again:
> Is there any telling how much the Roman Rite changed in the century
> prior to Trent? I am curious how different the missals used in Rome
> immediately before Trent were from the one authorized by Pius V.

very limited changes have been introduced by the Commission installed by s. Pius V : reminder once more "Trent" has nothing to do with that, except to mandate the pope for this reduced revision. Apart from the "rubrics", the Pian missal is making compulsory the Last Gospel, which was existing before but as a pious exercise. I've read it has also incorporated other minor changes. I've read the Pian missal is mainly a reprint of a Roman Curia missal dating around 1470.

That being said, there were numerous diocesan missals in the whole Latin Church, plus the particular rites/uses of some religious orders. The principal aim of the Pian missal was not to revise the Roman rite but to introduce more liturgical unity within the Latin Church, in a very soft manner : the pope confirmed all rites over 200 years, i.e. nearly all that were existing in 1570.

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* Luc Perrin is a professor at the University of Strasbourg 2 - Marc Bloch, where he teaches History of the Church.