Looking in the GR papers, what
@Sir Rhosis posted was the second outline, which is marked as having arrived in the Star Trek offices on March 17, 1967. There's an earlier outline, marked up by Bird, which Cash sez was submitted March 5, and
@Harvey has marked as March 10, 1967, but I don't see a date. Both were around the time writers were pitching stories for the second season. The author would only have had first season episodes as reference, and would likely be unaware of other stories being considered/developed.
A 3/23 letter from NBC's Stan Robertson to Roddenberry includes "[...]we are both in agreement this should be our final episode story of the forthcoming season in which we update, or attempt to go back and examine a society, system, or civilization of the past.[...]"
A 3/27 memo from sts (Star Trek Staff) nixes both the wolves and the Vulcan proconsul fighting Spock, suggesting they save the latter for a future story.
EDIT:
The DeForest Research reports indicate the credit changes:
- May 10: “BREAD AND CIRCUSES” BY JOHN KNEUBUHL
- Sept. 7: “BREAD AND CIRCUSES” BY JOHN KNEUBUHL AND GENE COON
- Sept 15: “BREAD AND CIRCUSES” BY GENE RODDENBERRY AND GENE L.COON (REVISED 9/12/67)
A Sept. 19, 1967 letter from Coon to the WGAw's Mary Dofman re the credits includes the following, which indicates the story springboard began at the Trek offices and was assigned to Kneubuhl:
[...]Gene Roddenberry and I sat down and developed the story idea, which you have in your possession at this time, included among other pertinent material. We then called in John Kneubuhl, gave him the story, which, while not completely developed, was considerably developed. John added a few pages to the story, we had it approved and then he went into First Draft; then into Second Draft. But he had many personal problems and his health failed him, and one day John called me and told me that he simply could not finish the screenplay and requested that he be withdrawn from the project.
This was granted. At this time, I went back to the original story, the one written by Roddenberry and me, and wrote a brand new First Draft, with different structure, dialogue, character development, and so on, which you will see in the first mimeographed copy of the script. When I had finished with a First Draft, Re-Write and a Polish, Gene Roddenberry stepped in and contributed a complete Re-Write, with new structure and character, based upon NOT THE KNEUBUHL SCRIPT, but upon my script, which was, in its turn, a complete original and not a simple Re-Write of the Kneubuhl effort.
Ordinarily, I would not go to such lengths, but since John Kneubuhl gave up completely on the script and returned the job to us, not only unfinished, but, in fact, unstarted-upon, since he had done no writing at all on his Re-Write as far as I know, I want to be sure the arbitration panel knows the full story.[...]