His updated version of an old-timey approach enhanced recordings by everyone from Bill Monroe to the Rolling Stones.Byron Berline, the acclaimed bluegrass fiddle player who expanded the vocabulary of his instrument while also establishing it as an integral voice in country-rock on recordings by Bob Dylan, the Rolling Stones and others, died on Saturday in Oklahoma City. He was 77.His death, in a rehabilitation hospital after a series of strokes, was confirmed by his nephew Barry Patton.Mr. Berline first distinguished himself as a recording artist when he was 21 on “Pickin’ and Fiddlin’,” an album of old-time fiddle tunes set to contemporary bluegrass arrangements by the innovative acoustic quartet the Dillards. The album features Mr. Berline’s heavily syncopated playing, along with long bow strokes that incorporate more than one note at the same time.Later in the decade, Mr. Berline’s lyrical phrasing was heard on pioneering recordings by country-rock luminaries like the Flying Burrito Brothers and the duo Dillard & Clark, featuring the Dillards banjoist Doug Dillard and the singer-songwriter Gene Clark, late of the Byrds. He also recorded with Elton John, Rod Stewart and Lucinda Williams, among many others.Weaving elements of pop, jazz, blues and rock into an old-timey approach to his instrument, Mr. Berline contributed instrumental selections to Bob Dylan’s soundtrack to Sam Peckinpah’s 1973 anti-western, “Pat Garrett and Billy the Kid.” He also overdubbed Nova Scotia-style fiddle on the Band’s 1976 single “Acadian Driftwood” and played on the albums “GP” (1973) and “Grievous Angel” (1974) by Gram Parsons, the country-rock progenitor and founding member of the Burrito Brothers.Mr. Parsons recommended Mr. Berline for what would become undoubtedly his most famous session appearance: the freewheeling fiddle part he added to “Country Honk,” the Rolling Stones’ down-home take on their 1969 pop smash “Honky Tonk Women.” Recorded in Los Angeles, the song was included on “Let It Bleed,” the group’s landmark album released that December.“I went in and listened to the track and started playing to it,” Mr. Berline said of his experience with the Stones in a 1991 interview with The Los Angeles Times.When he was summoned to the control booth, he recalled, he feared the band was unhappy with his work. Instead, they invited him to recreate his performance on the sidewalk along Sunset Boulevard, where the Elektra studio, where they were recording the track, was located. Hence the car horns and other ambient street sounds captured on the session.“There was a bulldozer out there moving dirt,” Mr. Berline said. “Mick Jagger went out himself and stopped the guy.”But Mr. Berline was not merely renowned for his work accompanying other artists; he was considered a musical visionary in his own right, providing leadership to, among others, the progressive bluegrass band Country Gazette.Mr. Berline was just 21 when he drew notice for his work on an album of old-time fiddle tunes by the innovative acoustic quartet the Dillards.In 1965, after hearing his playing on “Pickin’ and Fiddlin’,” the folklorist Ralph Rinzler invited Mr. Berline and his father, a fiddler himself, to appear as a duo at the Newport Folk Festival.While at Newport, Byron also had a chance to jam with the singer and mandolinist Bill Monroe, widely regarded as the father of bluegrass, who invited him to become a member of his band, the Blue Grass Boys. Then a student at the University of Oklahoma, Mr. Berline demurred; after completing his degree, he joined the Blue Grass Boys two years later.Mr. Berline spent only a few months with Monroe before being drafted into the Army, but bluegrass aficionados regard two of the three songs he recorded with him, “The Gold Rush,” written with Monroe, and “Sally Goodin,” as matchless performances.Mr. Berline was the winner of three national fiddle competitions and a member of the National Fiddler Hall of Fame.Byron Douglas Berline, the youngest of five children of Lue and Elizabeth (Jackson) Berline, was born on July 6, 1944, in Caldwell, Kan., near the Oklahoma border. His father worked a farm and played banjo and fiddle at barn dances and other events. His mother, a homemaker, played piano.Young Byron started playing a three-quarter-sized fiddle when he was 5; he won his first public competition at 10, outplaying his father. Among his early influences was Eck Robertson, the first old-time fiddler to appear on record.A gifted athlete, Mr. Berline earned a football scholarship to the University of Oklahoma, where he enrolled in 1963, only to fracture his hand that fall. The injury caused him to focus on music, although he maintained his athletic scholarship by joining the track team as a javelin thrower.Mr. Berline attracted the attention of the Dillards while playing in a campus folk group at Oklahoma. They invited him to play on “Pickin’ and Fiddlin’.” After graduating from college in 1967 and completing his military service in 1969, Mr. Berline moved to Los Angeles with his wife, Bette (Ringrose) Berline, at the urging of Doug Dillard, who recruited him to record with Dillard & Clark.After three years of session work in California, along with time in the Flying Burrito Brothers, Mr. Berline formed his own group, Country Gazette, and signed with United Artists Records. The band’s bluegrass blend proved influential, and it recorded for almost two decades, but Country Gazette never achieved mainstream success.Another project, Byron Berline & Sundance, likewise secured a deal with MCA Records. But the group’s three founding members, guitarist Dan Crary, banjo player John Hickman and Mr. Berline — later billing themselves as Berline, Crary & Hickman — fared best in a traditional bluegrass market, releasing records on independent labels like Rounder and Sugar Hill into the 1990s.Over the years Mr. Berline also provided music for television shows like “Northern Exposure” and movies like “Basic Instinct.” He also had a minor role as a musician in the Bette Midler movie “The Rose” (1979) and appeared, as part of a string quartet, in an episode of “Star Trek: The Next Generation.”Mr. Berline in 2004 at the Double Stop Fiddle Shop in Guthrie, Okla., which he and his wife, Bette, owned. The shop burned down in 2019; several months later, he opened another shop on the same street.Paul Hellstern for The New York TimesIn the mid-’90s, Mr. Berline and his wife moved to Guthrie, Okla., and opened the Double Stop Fiddle Shop, its name taken from the fiddle technique of playing two strings at the same time. The shop burned down in 2019, consuming its inventory of antique instruments. Several months later, Mr. Berline opened another shop on the same street.Mr. Berline is survived by his wife; a daughter, Becca O’Connor; a sister, Janice Byford; and four grandchildren.Although uncredited, Mr. Berline remarked in interviews that he did more than play the fiddle on Mr. Dylan’s soundtrack to “Pat Garrett and Billy the Kid.”“He said, ‘Can you sing?,’” Mr. Berline recalled, referring to Mr. Dylan in his 1991 interview.“I said, ‘Sure.’ So I got up and helped sing background vocals on ‘Knockin’ on Heaven’s Door.’” More