Alton Kelley, a graphic artist whose mind-blowing posters and album covers for the Grateful Dead, Big Brother & the Holding Company, and legendary San Francisco concert halls ushered in the psychedelic rock ‘n’ roll era, died Sunday at his home in Petaluma, Calif. He was 68 and had been suffering from osteoporosis.

Kelley and his long-time collaborator, Stanley “Mouse” Miller, created some of the most distinctive and memorable images in rock music, including the famous skull-and-roses emblem for the Grateful Dead and the “Girl With Green Hair” poster that advertised a concert at the Avalon Ballroom.

His work, with its colorful swirls, spiral designs, and exaggerated hand-drawn lettering, plastered telephone poles, head-shop windows, and vacant buildings in San Francisco in the 1960s. The handbills cost about $5 to print and were given away at the end of concerts. They now sell for tens of thousands of dollars to art collectors who compare them to the belle epoque art of such masters as Henri de Toulouse-Lautrec and Alphonse Mucha.

Kelley and Mr. Miller scored their first big hit with a 1966 poster advertising a concert of Big Brother & the Holding Company and the Quicksilver Messenger Service. The art was based on the logo of the Zig-Zag cigarette rolling-paper company.

“When Stanley and I did that poster, we got really paranoid,” Kelley said. “We figured, ‘Oh no. Now they know we smoke dope!’ And we took what little pot we had and flushed it down the toilet.”

The word on the streets of San Francisco at the time was that if you could not read the poster, you should not go to the concert, said rock historian Paul Grushkin, who wrote “The Art of Rock: Posters from Presley to Punk” (1987).

A native of Houlton, Maine, who had worked as a mechanic in a helicopter factory in Connecticut, Kelly raced motorcycles and drew cartoons of hot rods before he moved to San Francisco in 1964. He lived in a group house in Haight-Ashbury where he launched the Family Dog, an enterprise that set up weekend concerts with dancing and light shows, featuring local bands such as Jefferson Airplane, Country Joe & the Fish, and the Grateful Dead.

“Stanley and I had no idea what we were doing,” Kelley told the San Francisco Chronicle in 2007. “But we went ahead and looked at American Indian stuff, Chinese stuff, art nouveau, art deco, modern, Bauhaus — whatever. We had free rein to just go graphically crazy.”

Musicians including Pete Townshend and Mick Jagger sought out the pair, and Kelley moved into album art, designing six Grateful Dead album covers, the Pegasus image for Steve Miller’s 1977 album “Book of Dreams,” and three Journey albums in the late 1970s.

Corporations eventually took over the rock ‘n’ roll music scene. Kelley worked for a few years on album covers, then returned to an earlier love, hot rods. He illustrated the cars in fine-art oil paintings, then sold the images for T-shirts and other merchandise.