Unreleased for 50 years, this recording documents the debut gig by the Thad Jones/Mel Lewis Orchestra, an ensemble that pushed the big-band tradition light-years forward with its rhythmic intensity and bop-schooled sophistication. Trumpeter Jones and drummer Lewis would lead this band through a historic 12-year Vanguard residency; hearing how it all started, it’s obvious why the project caught fire. Any band that can navigate both the furious intensity of the churning, challenging “Back Bone” and the subzero cool swing of “Big Dipper” is something to shout about.