I added the below captions with trombone-related material from Arnaldo Morelli’s “The Role of the Organ in Performance Practices of Italian Sacred Polyphony during the Cinquecento,” Musica Disciplina, 1996, Vol. 50 (1996), 239-270. You can see them in historical context in the Trombone History Timeline (16th century).

1549—Florence, Italy: Lorenzo di Frosino, organist at Santa Maria del Carmine, is requested, on First Mass, to “bring a player of cornett and trombone [trombone torto]” (Morelli).

1575—Pistoia, Italy: At the church of Santissima Annunziata, there is a report of “a most beautiful music, especially on the organ with the cornetts and trombones [tromboni]” (Morelli).

1590—Padua, Italy: Father Valerio Polidoro describes music at Sant’ Antonio: “On several principal feast days these [singers] are joined by instrumentalists, with their portable organs—in addition to the [church’s] two large ones—trombones [tromboni], cornetts and violins” (Morelli).

1590—Genoa, Italy: A document governing the ducal musicians in Genoa stipulates that the 8 instrumental players (trombones and cornetts), “… are obliged to be in the church every time the most serene doge leaves the palace to go to church, playing in the organ loft or in another place if there is no organ, both when he enters and when he leaves, and during Mass as well if the most serene senate is present” (Morelli).