Foliar seed-bearing organs of paleozoic ginkgophytes and the early evolution of the ginkgoales

This paper deals with the Late Paleozoic phase of the evolution of the ginkgophytes (gymnosperms attributed to the order Ginkgoales). New genera and species of Permian gymnosperms are erected that are more or less confidently related to the Ginkgoales or belong to ancestral (for this order) pteridosperms with foliar seed-bearing organs: Cheirocladus longicheirus Naugolnykh, gen. et sp. nov. and Psygmophyllodendron uralensis Naugolnykh, gen. et sp. nov. A new family, Cheirocladaceae Naugolnykh, fam. nov., uniting gymnosperms with weakly modified foliar seed-bearing systems is proposed. The extended diagnosis of the family Psygmophyllaceae Zalessky emend. Naugolnykh, emend. nov. is provided. The extensive study of additional new material allowed the author to describe the morphology of Biarmopteris pulchra Zalessky (Cheirocladaceae), Psygmophyllum expansum (Brongniart) Schimper, and P. cuneifolium (Kutorga) Schimper (Psygmophyllaceae). Racemose aggregations of seeds of Karkenia sp. (Karkeniaceae), the oldest reliable record of Karkenia Archangelsky, are characterized. The typology of foliar seed-bearing organs of early ginkgophytes and morphogenetic transformations of the leaves of ginkgophytes are discussed.