Mortoniceras is an ammonoid genus belonging to the superfamily Acanthocerataceae, named by Meek in 1876, based on Ammonites vespertinu, named by Morton in 1834. Mortoniceras is the type genus of the Mortoniceratinae, one of 4 subfamilies in the Brancoceratidae which is part of the Acanthocerataceae (renamed Acanthoceratoidea to conform with the ICZN ruling on superfamily endings)