In some classifications, a class of gymnosperms comprising 4 orders: Cordaitales; Coniferales (conifers); Ginkgoales (ginkgos); and Taxales (yews). The Cordaitales appeared in the early Carboniferous and became extinct at the end of the Permian. The Coniferales appeared in the Upper Carboniferous, the Ginkgoales in the early Permian, and the Taxales in the Jurassic. These three are extant.