Jazz standard and Billy Strayhorn's "Take the 'A' Train" (1941). With the big bands struggling to keep going during World War II, a shift was happening in jazz in favor of smaller groups. Some swing era musicians, such as Louis Jordan, later found popularity in a new kind of music, called "rhythm and blues", that would evolve into rock and roll in the 1950s. Bebop emerged in the early 1940s, with Charlie Parker, Dizzy Gillespie and Thelonious Monk leading the way. It appealed to a more specialized audiences than earlier forms of jazz, with sophisticated harmonies, fast tempos and often virtuoso musicianship.
Debut Records Teo Macero, later a producer with Miles Davis, recorded his first album as a leader as a saxophonist for Debut, an album described by critic Dan Morgenstern as an oddball fusion of Lennie Tristano and Anton Webern. Debut was the label on which the "Jazz at Massey Hall" concert album was first issued. Recorded in Toronto, it features Dizzy Gillespie, Charlie Parker, Bud Powell, Charles Mingus, and Max Roach, and was the last recorded meeting of long-term musical partners Parker and Gillespie. In 1957 Danish bookseller Ole Vestegaard leased the company's catalogue from Mingus and produced recordings on the Danish