Answer:
The imagery on the lorica musculata cuirass (typical of legates [1] ) refers to the Parthian restitution of the Roman eagles, or insignia, in 20 BC, one of Augustus’ most significant diplomatic accomplishments. The date of the (hypothetical) bronze original is therefore later than 20 BC. The fact that Augustus is depicted barefooted is intended to be a divine representation, as this was a standard depiction of gods or heroes in classical iconography. The date of the marble copy would presumably fall between that date and Livia's death in AD 29.on:
