We describe distinctive characteristics of the magnum-trapezoid and other carpals found associated with an antler of the extinct genus Bretzia from southwestern Idaho from late Pliocene (Blancan V) Glenns Ferry Formation deposits (2.4 × 10⁶ years ago) of the Birch Creek drainage. This antler and elements of the foreleg represent a midpoint in the known evolutionary history of the genus. The oldest known antlers from a species of Bretzia are from the Pliocene Ringold sediments (4.2 × 10⁶ years ago) of Washington; and the most recent antlers are from South Dakota and Nebraska sediments of Rancholabrean–Holocene times (10,000–15,000 years ago). Carpal elements of the foreleg of Bretzia have a unique feature of the magnum-trapezoid not found in other extant New World cervids studied.