Complex sentence: He fought in what some consider to be the greatest heavyweight era of all-time, which included Muhammad Ali, Joe Frazier, George Foreman, Floyd Patterson, Jerry Quarry, Oscar Bonavena, George Chuvalo and Earnie Shavers, among others.
Split into simpler sentences: He fought in what some consider to be the greatest heavyweight era of all-time. The top heavyweights of the time included Muhammad Ali, Joe Frazier, George Foreman, Floyd Patterson, Jerry Quarry, Oscar Bonavena, George Chuvalo and Earnie Shavers, among others.