in the gillespie big band, jackson fell into a pattern that led to the founding of the modern jazz quartet: gillespie maintained a former swing tradition of a small group within a big band, and his included jackson, pianist john lewis, bassist ray brown, and drummer kenny clarke (considered a pioneer of the ride cymbal timekeeping that became the signature for bop and most jazz to follow) while the brass and reeds took breaks. when they decided to become a working group in their own right, around 1950, the foursome was known at first as the milt jackson quartet, becoming the modern jazz quartet (mjq) in 1952. by that time percy heath had replaced ray brown.