"One of the pillars of our city," Bun B said in tribute to the late Big Pokey. "If heart of gold was a person."
Onassis (real name: Johnny Rowan) drummed on the band's biggest hit: a cover of Neil Diamond's "Girl, You'll Be a Woman Soon" for the Pulp Fiction soundtrack.
"She was an important part of ALL that is Brazilian music in the world," said musician Paul Ricci.
She had been diagnosed in February 2021 with an incurable brain tumor.
The Grammy-winning lyricist worked with husband Barry Mann on dozens of hits over a six-decade career.
The cause of death for the mother of three with partner D.C. Young Fly has not been revealed.
The artist has collaborated with Daddy Yankee, Bad Bunny, Nicky Jam and many more.
The singer and actor toured extensively in musicals "Man of La Mancha," "Fiddler on the Roof," "South Pacific" and "I Do, I Do."
"Sheldon was an excellent addition to the band, a great writer and producer, and a genuinely kind and loving person."
McKean and her late husband Slim Dusty were the golden couple of Australia's country music scene.
