Petrophonics is Birdsongs of the Mesozoic's first album in five years and only the second to feature the lineup of Michael Bierylo (guitar), Ken Field (flutes, saxophones), Erik Lindgren (piano), and Rick Scott (synthesizers). The music has matured and if it's still highly eclectic, ranging from contemporary music to avant-jazz and prog-rock, approaches are better integrated into a distinctive "sound" and include an attempt at catching up with younger fans. Whether it is fruitful or not will depend on the listener's interest in turntable work (on two tracks). "Petrophonics" opens the album with a complex progressive rock motif backed by an annoying electronic bass drum -- enjoyable nonetheless. Field's "One Hundred Cycles" has a strange calypso groove topped by hot sax licks and guitar solos: a destabilizing number, very cheerful. "Study of Unintended Consequences" dives into avant-garde textures and atonal improvisation, while percussion abounds on "Birdhead," built on a track by Drumhead and bringing two musical visions into focus. But the album's highlight is comprised in the next four tracks, reworkings of the music Birdsongs wrote for the project 1001 Real Apes, a stage production with David Greenberger. This suite is as exciting as anything the band recorded in the past. The three-part "The Insidious Revenge of Ultima Thule" is another riveting piece of work, this one driven by Lindgren's piano, a kind of avant-rock concerto that brings the album to a beautiful halt. Fans of Birdsongs of the Mesozoic will be very happy with this release. If it weren't for the fact that the band aims at too many ducks in the course of the first seven cuts, this album would rank as their best. Well, maybe it still does.