Co-founded by Mr. Thomas in 1975, Pere Ubu became a stalwart of underground rock, influencing bands including Sonic Youth, Gang of Four, REM and the Pixies.

As a singer and songwriter, he pushed the boundaries of punk and art-rock, producing a half century of music, writings and performances and always upending expectations.

David Thomas, who fronted the boundary-pushing rock band Pere Ubu from the late 1970s forward, died Wednesday at age 71. The news was announced on the group’s Facebook page, where the cause of death was only given as the result of “a long illness.”