Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
Other elements of poetry were called into action in the primitive
popular carnival, the comic dance or -satura-,(5) which beyond
doubt reached back to a period anterior to the separation of the
stocks.
On such occasions song would never be wanting; and the
circumstances under which such pastimes were exhibited, chiefly
at public festivals and marriages, as well as the mainly practical
shape which they certainly assumed, naturally suggested that several
dancers, or sets of dancers, should take up reciprocal parts;
so that the singing thus came to be associated with a species of
acting, which of course was chiefly of a comical and often of a
licentious character.
In this way there arose not merely alternative
chants, such as afterwards went by the name of Fescennine songs, but
also the elements of a popular comedy--which were in this instance
planted in a soil admirably adapted for their growth, as an acute
sense of the outward and the comic, and a delight in gesticulation
and masquerade have ever been leading traits of Italian character.