Bassist Rob Wasserman, whose incredibly diverse career is best known for his work with Grateful Dead star Bob Weir in the group Ratdog, has died after a battle with unknown health issues.

Weir confirmed the sad news via social media tonight, after reporting earlier today that his friend and longtime musical collaborator was in the midst of "a serious health struggle." As of this posting the nature of his ailment has not been reported.

There is much, much more to Wasserman's story than his time with Ratdog. A classically trained violinist in his youth, he switched to bass at age 20 and released his first jazz album, the acclaimed Solo, in 1983. He released four more solo albums over the next two decades, the most recent being 2005's jazz-rock fusion effort Cosmic Farm.

As reported by Vintage Vinyl News, Weir and Wasserman began teaming up in the late '80s, performing together over the years as members of Weir/Wasserman, Scaring the Children, Friends of Montezuma and Ratdog. The latter group's lone studio album was 2000's Evening Moods, but the popular band continued playing live regularly for another decade until Weir shifted his focus to the group Further, which featured former Grateful Dead bassist Phil Lesh.

Over his long and distinctive career, Wasserman also recorded with Van Morrison, Lou Reed, Elvis Costello and Rickie Lee Jones among many others. He is credited with performing the stand-up electric bass solo on the song "Junior Dad," from Reed and Metallica's 2011 album Lulu.

Jane's Addiction drummer Stephen Perkins, whose jazz-influenced art rock band Banyan counted Wasserman among its part-time members, also paid his respects by tweeting, "So sad to hear about Rob Wasserman passing - I had so many great jams with him."

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