By Piya Sinha-Roy

LOS ANGELES (Reuters) - Led Zeppelin may owe an American musician millions of dollars in royalties, a plaintiff's attorney said on Wednesday in closing arguments of a trial over whether the British band stole the opening riff for its 1971 hit "Stairway to Heaven."

Led Zeppelin guitarist Jimmy Page, in testimony earlier in the seven-day copyright infringement trial, said the riff was commonly used long before its appearance on American band Spirit's 1967 song "Taurus" and before "Stairway to Heaven."

Lawyer Francis Malofiy, who represents a trustee for late Spirit musician Randy Wolfe, also known as Randy California, told jurors in U.S. District Court in Los Angeles that Page did not say how he was inspired to compose the opening chords of the chart-topping song, which has a place in the Grammy Hall of Fame.

"He didn't tell you where he got the idea," Malofiy said. "That's because the piece of music was lifted from 'Taurus' and Randy California."

Malofiy said he was seeking a one-third writing credit on "Stairway to Heaven" for Wolfe and presented various estimated valuations of damages ranging from $3 million to $30 million.

The federal trial has called into question the originality of the signature song of one of the top-selling rock acts of all time.

Peter Anderson, an attorney for the band, repeated to jurors his argument that the riff that opens "Stairway to Heaven," a chromatic descending arpeggiated line that misses the 'E' note, was in the public domain and had been widely used.

"Randy Wolfe did not create the descending chromatic scale," Anderson told jurors.

Anderson also questioned the damage figures sought by Malofiy, telling jurors that even if they decide Wolfe deserves a writing credit, they would have to determine the value of a riff that only forms part of "Stairway to Heaven."

The lawsuit was brought in 2014 by Michael Skidmore, a trustee for Wolfe. The musician drowned in 1997.

Earlier in the trial, Skidmore's lawyers simultaneously showed the jury two video clips of expert Kevin Hanson playing the riff in both songs. Hanson said the two clips "play together as one piece of music. It is not discordant."

Led Zeppelin's attorneys brought in music expert Lawrence Ferrara, who testified that the "descending chromatic minor line progression" in question at the trial was used 300 years ago, as well as in many pop songs since.

(Writing by Alex Dobuzinskis; Editing by Peter Cooney)