Jan 10 - Veteran rock musician Bob Weir, the Grateful Dead's rhythm guitarist who helped guide the legendary jam band through decades of change and success, has died at age 78, according to a statement posted to his verified Instagram account on Saturday.

He was diagnosed with cancer in July and "succumbed to underlying lung issues" surrounded by loved ones, the statement said. It did not mention when or where he died.

Along with his late fellow Grateful Dead co-founder and lead guitarist Jerry Garcia, who was at the center of the Deadhead universe, Weir was one of the group's two frontmen and main vocalists for most of the band's history.

It was Weir who sang the verses on the band's trademark boogie anthem, "Truckin'," and who wrote such key songs as "Sugar Magnolia," "Playing in the Band" and "Jack Straw." 

The youthful, ponytailed "Bobby" grew into an eclectic songwriter whose handsome appearance and diverse musical influences helped broaden the band's appeal. British newspaper The Independent called Weir "arguably rock's greatest, if most eccentric, rhythm guitarist."

After Garcia's death at age 53 in 1995, Weir carved out an interesting if somewhat neglected solo career - much of it with his band, RatDog - and participated in reunions of surviving Dead members in different configurations.

LONG STRANGE TRIP

"As the one good-looking guy in the Dead, baby-faced Weir was always what passed for the band's sex symbol," the San Francisco Chronicle's Joel Selvin wrote in 2004. "He didn't care about that, either. In fact, he always seemed to secretly relish subverting that image." 

Weir was the subject of the 2014 documentary "The Other One: The Long, Strange Trip of Bob Weir," which made a case for the Dead's "other" guitarist as a musical force. Though some diehard Dead fans, or "Deadheads," adopted the trappings of tie-dyed psychedelia, the group itself was deeply attached to American roots music and was credited with bringing experimental improvisation to rock music.

Weir's own mus...