Lyginopteridales

Lyginopteridales Temporal range: Famennian–Lopingian PreꞒ Ꞓ O S D C P T J K Pg N
Diplopteridium holdenii, Early Carboniferous Drybrook Sandstone, Forest of Dean, UK.
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Division:	†Pteridospermatophyta
Class:	†Lyginopteridopsida
Order:	†Lyginopteridales
Families
Moresnetiaceae Genomospermaceae Eospermaceae Lyginopteridaceae Physostomaceae[1]

The Lyginopteridales are an extinct group of seed plants known from the Paleozoic. They were the first plant fossils to be described as pteridosperms (a polyphyletic group sometimes referred to as "seed ferns") and, thus, the group on which the concept of pteridosperms was first developed;^[2] they are the stratigraphically oldest-known pteridosperms, occurring first in late Devonian strata;^[3] and they have the most primitive features, most notably in the structure of their ovules.^[4] They probably evolved from a group of Late Devonian progymnosperms known as the Aneurophytales,^[5] which had large, compound frond-like leaves. The Lyginopteridales became the most abundant group of pteridosperms during Mississippian times, and included both trees^[6] and smaller plants.^[3] During early and most of middle Pennsylvanian times the Medullosales took over as the more important of the larger pteridosperms but the Lyginopteridales continued to flourish as climbing (lianescent) and scrambling plants. However, later in Middle Pennsylvanian times the Lyginopteridales went into serious decline, probably being out-competed by the Callistophytales that occupied similar ecological niches but had more sophisticated reproductive strategies. A few species continued into Late Pennsylvanian times, and in Cathaysia and east equatorial Gondwana they persisted into the Late Permian, but subsequently became extinct.^[7] Most evidence of the Lyginopteridales suggests that they grew in tropical latitudes of the time, in North America, Europe and China.