The term Pteridospermatophyta (or seed ferns” or “Pteridospermatopsida”) is a polyphyletic wastebasket taxon of extinct seed-bearing plants (spermatophytes). The earliest fossil proof for plants of this kind is the genus Elkinsia and the Lyginopterids of late Devonian age. They flourished significantly throughout the Carboniferous and Permian durations. Pteridosperms declined during the Mesozoic Era and had largely disappeared by the end of the Cretaceous Period, though some pteridosperm-like plants appear to have survived into Eocene times, based on fossil finds in Tasmania. With regard to the enduring utility of this division, many palaeobotanists nonetheless use the pteridosperm grouping in an informal sense to seek advice from the seed plants that are not angiosperms, coniferoids (conifers or cordaites), ginkgophytes or cycadophytes (cycads or bennettites). This is particularly helpful for extinct seed plant teams whose systematic relationships remain speculative, as they can be classified as pteridosperms with no legitimate implications being made as to their systematic affinities.
