Herald
Part of speech: noun
Definition: A messenger, especially one bringing important news. A harbinger, giving signs of things to come. An official whose speciality is heraldry, especially one between the ranks of pursuivant and king of arms.
Part of speech: verb
Definition: To proclaim, announce, etc. an event.
Precursor
Part of speech: noun
Definition: That which precurses, a forerunner, a predecessor, an indicator of approaching events.One of the compounds that participates in the chemical reaction that produces another compound.