Paramount and Warner Bros. have signed David Fincher to direct a pair of tentpoles – “Zodiac,” starring Mark Ruffalo, and “The Curious Case of Benjamin Button,” with Brad Pitt and Cate Blanchett – back-to-back. Fincher, whose last film was 2002’s “Panic Room,” is in pre-production on “Zodiac,” which also stars Robert Downey Jr., Jake Gyllenhaal and Anthony Edwards. Production is slated to start in September, with Jamie Vanderbilt adapting from Robert Graysmith’s “Zodiac” and 2002 sequel “Zodiac Unmasked: The Identity of America’s Most Elusive Serial Killer Revealed.” Fincher and partner Cean Chaffin are producing with Vanderbilt and Phoenix principals Mike Medavoy, Arnold Messer and Brad Fischer. Shooting will take place in San Francisco – where the Zodiac Killer operated starting in the late 1960s – and in Los Angeles. Par and Warner are aiming for Fincher to start lensing “Benjamin Button” in October 2006. Fitzgerald’s story “The Curious Case of Benjamin Button” centers on a man who, at age 50, begins aging backward and the complications that ensue when he falls in love with a woman of 30.