The last surviving original member of the classic Southern rock group, he played the soaring slide guitar solo on “Free Bird” and co-wrote “Sweet Home Alabama.”Gary Rossington, an original member of Lynyrd Skynyrd, the quintessential Southern rock band, whose guitar helped define its sound and who was a key figure in the group’s eventual rebirth after a plane crash in 1977 killed three of its members, died on Sunday. He was 71.The band posted news of his death on its Facebook page but did not say where he died. No cause was given, although Mr. Rossington had had heart problems for years. He was the last surviving member of the original band.Growing up in the Jacksonville, Fla., area, Mr. Rossington got the rock-star bug when a friend, Bob Burns, was given a drum kit in the summer of 1964. The two teenagers decided they would become rock drummers.“The practical limitations of forming a band with only two drummers soon became apparent,” Mr. Rossington’s biography on the band’s website notes, “and Gary gravitated toward playing the guitar.”That same summer, according to a portrait of the band written for the Rock & Roll Hall of Fame, which inducted the group in 2006, another teenager, Ronnie Van Zant, was playing in a baseball game when he hit a foul ball that struck a spectator, Mr. Burns. Mr. Van Zant, too, had rock-star aspirations, and the three began playing together, adding other members and trying out group names — the Wildcats and Sons of Satan were among those considered.Eventually they settled on Lynyrd Skynyrd, a bastardization of Leonard Skinner, a gym teacher who had hassled them in high school because of their long hair.The band, playing countless bar dates around Florida and eventually beyond, evolved into a seven-piece with three guitars — Mr. Rossington, Allen Collins and Ed King (later replaced by Steve Gaines) — backing Mr. Van Zant’s vocals. The guitarists would alternate as lead, sometimes in the same song. Mr. Rossington was adept as a lead and also had a knack for adjusting his style to support the other guitarists when one of them was front and center.“Back in the day, we had three guitars and a keyboard, so that’s all strings,” he told the website Premier Guitar in 2017. “It’s hard to get all those strings together, and the hardest part is not playing. Growing up, we learned where not to play. Even though you could play, you leave the space and room.”The band’s breakthrough came in 1973, when the musician and producer Al Kooper caught a show in Atlanta, liked what he heard and signed the group to his Sounds of the South label. Mr. Kooper produced the band’s first album, “Lynyrd Skynyrd (pronounced ‘lĕh-’nérd ‘skin-’nérd),” which was released in 1973 and included “Gimme Three Steps,” “Simple Man” and what became one of rock’s most famous songs, “Free Bird,” with Mr. Rossington’s evocative slide guitar solos.By the fall of 1977, the group had released four more albums, had hits with “Sweet Home Alabama” (which Mr. Rossington wrote with Mr. Van Zant and Mr. King) and other songs, and was one of the best-known bands of the day. Then, on Oct. 20, the band’s chartered plane ran out of fuel and crashed in a thicket in Mississippi, killing Mr. Van Zant; Mr. Gaines; Cassie Gaines, Mr. Gaines’s sister and a backup vocalist; the band’s road manager; the pilot; and the co-pilot. The 20 other passengers were injured, including Mr. Rossington, who sustained numerous broken bones.The crash was the end of Lynyrd Skynyrd, for a time. After a few years to recover physically and psychologically, Mr. Rossington and Mr. Collins formed the Rossington Collins Band, which strove to distinguish itself from Lynyrd Skynyrd, in part by hiring a female vocalist, Dale Krantz, whom Mr. Rossington would later marry.But the new band did play “Free Bird” at its shows.“We do it now as an instrumental,” Mr. Rossington told The Orlando Sentinel in 1980. “We don’t do the vocal on it because that was Ronnie’s. It still gets heavy when we play it. I can hear him singing.”In 1987, the 10th anniversary of the crash, Mr. Rossington helped bring about a tribute tour, reuniting surviving members, with Mr. Van Zant’s younger brother, Johnny, taking over as vocalist.Mr. Rossington, right, duets with Rickey Medlocke in the reconstituted Lynyrd Skynyrd in Fort Hood, Tex., in 2004.Steve Traynor/The Killeen Daily Herald, via Associated Press“We were just going to do a one-show thing,” he told The Los Angeles Times that year, “but it turned into a tribute tour because, 10 years later, the music’s still being played on the radio, and it’s still requested, and it’s still selling real good.”The reconstituted group stuck, and it has been touring as Lynyrd Skynyrd, with various lineups, ever since, as well as releasing albums. Later this year the band is scheduled to tour with ZZ Top. Mr. Rossington, though, had cut back his participation to only occasional appearances, for health reasons.Mr. Rossington was born on Dec. 4, 1951, in Jacksonville. His father died when he was a boy, and his mother was an important force in his life, so much so, he said, that he named his first serious guitar, a Les Paul, “Berniece” after her.In a 1993 interview with The Associated Press, Mr. Rossington recalled some early validation for the fledgling group: winning a battle of the bands in Jacksonville in 1968.“There were 10 bands playing soul music,” he said. “We came in and did Yardbirds and Stones. We were a little over the audience’s heads. Except that the judges went, ‘These cats are cool.’”Mr. Rossington, right, with Lynyrd Skynyrd in 2019. He cut back his participation in the band in recent years because of health problems.Suzanne Cordeiro/Agence France-Presse — Getty ImagesMr. Rossington and other band members were known for a wild lifestyle. In 1976 Mr. Rossington smashed his car, with alcohol and drugs contributing to the accident. The crash inspired the band’s song “That Smell,” a track on its 1977 album, “Street Survivors.”In addition to his wife, Mr. Rossington’s survivors include two daughters.When Mr. Rossington and the others in the tribute group of 1987 gave their first concert, in Nashville, they played “Free Bird” as an instrumental, as Mr. Rossington had in his earlier group. The audience filled in for the absent Ronnie Van Zant.“You could hear 16,000 people singing,” Mr. Rossington said, “and it sounded like a million.” More