Many of the big bands who were deprived of experienced musicians because of the war effort began to enlist young players who were below the age for conscription, as was the case with saxophonist Stan Getz's entry in a band as a teenager. This coincided with a nationwide resurgence in the Dixieland style of pre-swing jazz; performers such as clarinetist George Lewis, cornetist Bill Davison, and trombonist Turk Murphy were hailed by conservative jazz critics as more authentic than the big bands. Elsewhere, with the limitations on recording, small groups of young musicians developed a more uptempo, improvisational style of jazz, collaborating and experimenting with new ideas for melodic development, rhythmic language, and harmonic substitution, during informal, late-night jam sessions hosted in small clubs and apartments. Key figures in this development were largely based in New York and included pianists Thelonious Monk and Bud Powell, drummers Max Roach and Kenny Clarke, saxophonist Charlie Parker, and trumpeter Dizzy Gillespie. This musical development became known as bebop.