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Jack Sheldon, once known to America’s schoolkids as the voice behind “I’m Just a Bill,” "Conjunction Junction" and other songs on “Schoolhouse Rock,” and to older TV viewers as a sidekick of talk-show host Merv Griffin, has died at age 88.

Sheldon succumbed Friday to natural causes, his longtime manager and partner, Dianne Jimenez, said in a statement Tuesday, according to The Associated Press. No further details were provided.

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An acclaimed jazz musician who played trumpet on the award-winning song “The Shadow of Your Smile,” Sheldon was a prominent part of the vibrant West Coast jazz movement in the 1950s alongside fellow artists Art Pepper, Stan Kenton and Shorty Rogers. He also played with jazz and pop greats including Benny Goodman, Peggy Lee, Lena Horne and Frank Sinatra.

“The Shadow of Your Smile” was introduced in the 1965 film “The Sandpiper.” It won a Grammy as song of the year and an Oscar for best original song.

Born in 1931 in Jacksonville, Fla., Sheldon started playing the trumpet professionally as a youth and moved to Los Angeles in 1947. He served in the Air Force, playing in several military bands.

He also found work as an actor, with TV credits including the 1966-67 comedy series “Run Buddy Run,” the 1970s series “The Girl With Something Extra" opposite Sally Field and in episodes of “The Simpsons,” “Family Guy” and “Star Trek: The Next Generation.”

Jack Sheldon, an accomplished jazz trumpet player, was also a talented actor, comedian and singer who recorded several songs for the "Schoolhouse Rock"  television series, including "I'm Just a Bill."

Jack Sheldon, an accomplished jazz trumpet player, was also a talented actor, comedian and singer who recorded several songs for the "Schoolhouse Rock"  television series, including "I'm Just a Bill."

He appeared on Griffin’s show for most of its run from 1962 to 1986.

Sheldon’s films included 1991’s “For the Boys,” in which he played a World War II bandleader opposite Bette Midler and James Caan and the documentary “Let’s Get Lost,” about fellow trumpet player Chet Baker.

His gravelly voice was heard in more a dozen episodes of the educational animated children’s series “Schoolhouse Rock!”, including “I’m Just a Bill,” written by Dave Frishberg. The song tells the tale of a legislative bill that journeys through Congress with the goal of becoming a law.

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"At least I hope and pray that I will," he sings, "but today I am still just a bill."

Sheldon’s health problems in recent years included colon cancer in 1996 and strokes in 2005 and 2001, The Associated Press reported. He is survived by his longtime partner Jimenez and children Jessie and John.

The Associated Press contributed to this story.