Tenor saxophonist Fred Anderson, perhaps the most beloved elder in Chicago jazz, died yesterday at 81. He’d suffered a massive heart attack on June 14 while hospitalized for stomach pain at Saint Francis Hospital in Evanston, and he passed away in hospice in Park Ridge. Anderson, a singular player with a distinctly Chicagoan sound, was a giant of free jazz, and exerted a powerful influence with much more than his muscular, blues-imbued style: he was also a mentor to many important players, among them trombonist George Lewis, drummer Hamid Drake, and reedists Douglas Ewart and Matana Roberts, and he owned and ran the Velvet Lounge, which opened in 1981 and became a crucial venue for visiting artists and locals alike, hosting a weekly Sunday jam session that has long nurtured countless emerging musicians.