Dating of the Synoptic Gospels:
Assuming Markan Priority, then Matthew and Luke used the gospel of Mark as a source.
1) Mark was written in the 50's or early 60's.
2) Matthew was written in the late 50"s or the 60's.
3) Luke was written between 59 and 63.
Assuming Matthew and Luke did NOT use Mark as a source.
1) Mark written 65-70.
2) Matthew written in the 50's.
3) Luke written between 59 and 63.
Another open question is whether John Mark was an "interpreter" of Peter's sermons. Note the parallel sequence of Peter's sermon, starting with John the Baptist Acts 10:37 and Mark.