Complex sentence: The Opiconsivia festival was superintended by the Vestals and the Flamines of Quirinus, an early, Sabine god said to be the deified Romulus, absorbed by and included in the first and earliest Capitoline Triad, along with Mars--then an agriculture god--and Jupiter.
Split into simpler sentences: The Opiconsivia festival was superintended by the Vestals and the Flamines of Quirinus, an early, Sabine god said to be the deified Romulus. Quirinus was absorbed by, and included in, the first and earliest Capitoline Triad, along with Mars--then an agriculture god--and Jupiter.