prior to the Romans, the shofar was blown at Shachris. But we don't say malchius, zichronos and shofros at Shachris?
allen schuldenfrei, baltimore, MD
The Ran on the Rif asks your question and answers that when the Shofar was blown during Shacharis so too were the three Berachos of Machuyos, Zichronos, and Shofros added to Shacharis (also brought by the Tosfos Yom Tov).
The Ran also brings the Ba'al ha'Ma'or's opinion that all Tefilos of Rosh Hashanah were 9 Berachos, but he argues on him.
All the best,