(2) Suborder Spiriferidina . Theses are strophic spiriferids, whose pedicle valve interarea is well developed. The orientation of the spiralia are perpendicular to the commissural plane and parallel to the plane of symmetry in brachiopods. Spirifirids typically have a well defined fold and sulcus and are frequently ornamented with radial plicae and/or costae. Commonly (but not exclusively) spiriferids are alate shaped such as Mucrospirifer from the Middle Devonian of New York.