Complex sentence: After its cancellation, "The Flintstones" became the first primetime animated series to last more than two seasons; this record wasn't surpassed by another primetime animated TV series until the seventh season of "The Simpsons" in 1995/1996.
Split into simpler sentences: After its cancellation, "The Flintstones" became the first primetime animated series to last more than two seasons. This record wasn't surpassed by another primetime animated TV series until the seventh season of "The Simpsons" in 1995/1996.