This being my third in a series of reviews of films involving the stop-motion animator Willis O'Brien, this particular one has an interesting sequence in which one of the cavemen is ripped apart between his bare chest and fur skirt with his bare chest part being thrown to a tree branch by the dinosaur that he was riding on! This short involves a mailman, a woman he tries to have his way with, and another man who she prefers. I'll stop there and just say that the particular sequence I just mentioned was the most entertaining part of this 12-minute film which I watched with no music score. (I had just previously watched a 4-minute version missing some of the beginning scenes with a piano score playing that confused me so I'm glad I got the watch the longer one right after that, both on YouTube.) So that's a recommendation of R.F.D 10,000 B.C.