As bebop evolved, smaller jazz groups dropped the guitar, and many free jazz ensembles dropped the piano as well. Auxiliary percussion such as claves, bongos or maracas can also be used, especially in music influenced by strains from Latin America such as salsa and samba. In theory any instrument or instruments can provide a steady rhythm: for example, in the trio led by Jimmy Giuffre the late 1950s, the clarinet, valve trombone and guitar all switched between lead and supporting roles.