BUENOS AIRES (AP).- A Spanish collector plans to auction what he claims is a newly discovered 8-mm version of a film purportedly showing Marilyn Monroe having sex when she was still an underage actress known as Norma Jean Baker. A Marilyn Monroe expert, however, says the actress in the film is someone else, considerably heavier and less feminine than the legendary film star. “That’s not Marilyn. The chin is not the same, the lips are not the same, the teeth are not the same,” said Scott Fortner, who has a sizeable collection of Monroe memorabilia, including a belt he said proves how much more petite she was. “Marilyn was a tiny little thing. And I know that for a fact. I own her clothing.” Collector Mikel Barsa said in an interview Wednesday that he wants at least $500,000 for the sexually explicit 6½-minute, grainy black-and-white film, which he says was made before 1947, when Monroe was not yet 21. He said it’s an exact copy of a 16-mm film discovered more than a decade ago.