Cornetist Rob Mazurek’s Chicago Underground group has assembled a compelling post-bop canon while fluctuating between anything from a duo to an orchestra. The Trio, rounded out by bassist Noel Kupersmith and drummer Chad Taylor, is where he sounds most at home. Mazurek nimbly hops from beat to beat on “Shoe Lace,” evoking cornet legend Don Cherry’s duels with Billy Higgins. Slon is no musty throwback, though; while the menacing drones of “Kite” protest too much (and leave Mazurek sounding tentative), Taylor’s rolling percussion exhibits touches of both jungle and Elvin Jones, and the band’s stretches of electronica sound admirably unforced.