Some specimens From the Jurassic-Cretaceous boundary of Australia may belong to the Group
Life restoration of theLepidopteris plant, withLepidopteris ottonis foliage andAntevsia zeilleri pollen-producing microsporophylls, from the Late Triassic of Europe
Life restoration ofFurcula granulifer from the Late Triassic of Greenland
ThePeltaspermales are an extinctorder ofseed plants, often considered "seed ferns".[2] They span from the Late Carboniferous to the Early Jurassic or the Jurassic-Cretaceous Boundary. It includes at least one valid family,Peltaspermaceae, which spans from the Permian to Early Jurassic, which is typified by a group of plants withLepidopteris leaves,Antevsia pollen-organs, andPeltaspermumovulate organs, though the family now also includes other genera likePeltaspermopsis,Meyenopteris andScytophyllum.[3] Along with these, two informal groups (the "Supaioids"[4][5] and the "Comioids"[6]) of uncertain taxonomic affinities exist, each centered around a specific genus;Supaia andComia, known from the Early Permian of the Northern Hemisphere, especially of North America.[4][6] Both the "Comioids" and the "Supaioids" are associated with the peltaspermacean ovulate organAutunia (also known asSandrewia).[7][8] The Late Triassic-Middle Jurassic genusPachydermophyllum may also have affinities to the peltasperms.[3]
The morphology of peltasperm leaves is highly variable, ranging from dissectedpinnate (fern-like) to forked andsimple morphologies. The leaves of many peltasperms have "monocyclicstomata with wedge-shaped subsidiaries ending in a beak-like papilla overarching the guard cells", something which is found among other seed plant groups. The seed-bearing organs are generally fan-shaped or peltate.[9]
It is unclear whether the broad grouping of peltasperms as a whole ismonophyletic.[2] Some authors have suggested that some peltasperms may have close affinities tocorystosperms, another group of extinct "seed ferns".[3] Meyen (1987) argued that Peltaspermales were ancestral toGinkgoales, due to similarities between certain peltasperm form genera (Tatarina,Kirjamkenia,Stiphorus,Antevsia) and the extinct ginkgoGlossophyllum, and grouped peltasperms with Ginkgoales as part ofGinkgoopsida.[10] Later authors have considered the position of Peltaspermales within seed plants to be uncertain.[9]
It is suggested that at least some peltasperms may have beeninsect pollinated, with Pemian members of the long-probiscisscorpionfly familyProtomeropidae from Russia associated with peltasperm pollen. The insects are suggested to have fed on pollination drops produced by peltasperm reproductive organs.[11]
During the late Paleozoic, peltasperms are primarily known from the Northern Hemisphere,[3] withLepidopteris first appearing in the region during the Late Permian.[12] During theTriassic,Lepidopteris became globally distributed and was abundant, especially during the Late Triassic.Lepidopteris populations collapsed during theend-Triassic mass extinction,[3][13][14] with small populations persisting in Patagonia into the Early Jurassic.[3] The genusPachydermophyllum, along specimens referred asLepidopteris? from theBattle Camp Formation ofClack Island, of latest Jurassic or earliest Cretaceous age may indicate an even longer survival in Gondwana.[15]
^abChaney, Dan S., Mamay, Serguis H., DiMichele, William A., and Kerp, Hans. 2009. "Auritifolia gen. nov., Probable Seed Plant Foliage with Comioid Affinities from the Early Permian of Texas, U.S.A."International Journal of Plant Sciences, 170, (2) 247–266.https://doi.org/10.1086/595293.
