How is it possible, one might reasonably ask, that 58 previously unreleased recordings by Charlie Parker—who died in 1955—managed to stay hidden until now? The tracks on this new two-CD collection, which also includes another 11 that have seen the light of day before, apparently came from the archives of the late Verve Records founder Norman Granz. The liner notes, by longtime jazz historian Phil Schaap, don’t delve into where the tapes have been squirreled away all these years but, in any case, it’s a significant find. Significant, but not game-changing. Cut between 1949-52, the newly unearthed tracks vary in both audio and performance-quality, and many are incomplete snippets or false starts, works-in-progress not always worth hearing more than once—except for the most die-hard of Birdophiles. But among the full alternate takes, there are gems to be discovered: small group and orchestral numbers, Latin-tinged jams and more. One of the first here is an alternate of “Visa,” a 1949 track by a swinging septet featuring trumpeter Kenny Dorham and trombonist Tommy Turk among its stellar cast. Backed by an ace rhythm section (including drummer Max Roach), the horn men trade solos that are just different enough from the master take to draw attention to their creative instincts. A 1950 all-star quartet, with Buddy Rich drumming, also satisfies. Later in the set, a series of collaborations between Parker and the equally celebrated Dizzy Gillespie add context to their already legendary sessions, but some of the most revealing music comes at the tail end: fascinating alternate takes of Parker’s sassy, brassy renditions of three swinging Cole Porter numbers: “Night and Day,” “Almost Like Being in Love” and “What Is This Thing Called Love.”