On September 30 1960, at 8:30 PM, ABC network aired the first episode of “The Flintstones”. The late broadcast hour was a recognition that initially “The Flintstones” were made with an adult audience in mind, a cartoon version of that new TV genre, the sitcom. The adventures of the two Stone Age families, the Flintstones and the Rubbles, went on for six seasons, initially a great hit, slipping in ratings in later seasons.