Mark, then is to be dated either in the late fifties or the middle sixties. While the latter is the majority view, we favor the late fifties. Indeed, we are required to date Mark before A.D. 60 if our assumptions about the ending of Acts and the priority of Mark are valid...Dating Mark in the fifties does go against the earliest traditions about Mark having been written after the death of Peter. But other traditions affirm that Mark wrote while Peter was still alive, so the early evidence is by no means unanimous on the subject (Carson, et. al., 1992).
Mark's connection with the second gospel is asserted or assumed by many early Christian writers. Perhaps the earliest (and certainly the most important) of the testimonies is that of Papias, who was bishop of Hierapolis in Phrygia of Asia Minor until about A.D. 130. His statement about the second gospel is recorded in Eusebius's History of the Church (Historia Ecclesiastica), written in 325...Those who are skeptical of the reliability of Papias conclude that the author of the gospel is unknown. Yet, as we have seen, there is nothing in the New Testament that is inconsistent with Papias's claim that Mark wrote the second gospel. And since we have no indication that anyone in the early church contested Papias's claim, we see no reason not to accept it (Carson, et. al., 1992).