An extinct order of the class Pinopsida comprising a natural grouping of Paleozoic forest trees or shrubs that first appeared in the Lower Pennsylvanian. They became an important component of the tropical vegetation during the Middle and Upper Pennsylvanian and diminished during the basal Permian. The Cordaitales were divided into three families, Cordaitaceae, Pityaceae, and Poroxylaceae. However, members of the Pityaceae and Poroxylaceae are now known to be either seed ferns or progymnosperms, so only the Cordaitaceae remain. Detailed information about these prominent Paleozoic gymnosperms comes from impression-compression fossils and sandstone casts. However, coal balls, which are mineral nodules in which the plants are preserved with three-dimensional anatomy, have been essential to establishing whole-plant concepts of cordaitean species.