Summarizing in broad strokes Liturgical developments in the Roman Rite after Constantine to the seventh century, we can mention the compilation of certain texts that were used as models for the celebration of various liturgical celebrations, known as sacramentaries(10). The most prominent of these were the Veronense (Leonine) Sacramentary, the Gelasian, and the Gregorian Sacramentaries. The Veronense Sacramentary is a collection of booklets containing the presider’s prayers for the Mass, including proper collects for the day, opening prayer, offertory prayer, and the prayer after communion(11). The Gelasian Sacramentary was used by presiding presbyters in Roman Churches. Both the Gelasian and the Gregorian Sacramentaries were taken to the Franks in the 8th century, where they were further adapted according to their customs, using elements of the Gallican Rite used there(12). The existence of these texts shows the very complex process of the growth and gradual formation of the parts of the liturgy, and the great diversity of liturgical prayers that existed. This process of development of the Roman Rite liturgy is ignored by some who would enshrine the liturgy of Trent as it was celebrated in the 1960’s as something eternal, never to be tampered with. The liturgy of Trent was a result of much development as well as the integration of liturgical elements from different regions, as we will now see.
10. New Catholic Encyclopedia – Sacramentaries