| Peltaspermales Temporal range: Some specimens From the Jurassic-Cretaceous boundary of Australia may belong to the Group | |
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| Life restoration of the Lepidopteris plant, with Lepidopteris ottonis foliage and Antevsia zeilleri pollen-producing microsporophylls, from the Late Triassic of Europe | |
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| Life restoration of Furcula granulifer from the Late Triassic of Greenland | |
Scientific classification  | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Spermatophytes |
| Order: | † Peltaspermales Delevoryas 1979 [1] |
| Families and genera | |
See text | |
The Peltaspermales are an extinct order of seed 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 with Lepidopteris leaves, Antevsia pollen-organs, and Peltaspermum ovulate organs, though the family now also includes other genera like Peltaspermopsis , Meyenopteris and Scytophyllum . [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 and Comia, 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 organ Autunia (also known as Sandrewia). [7] [8] The Late Triassic-Middle Jurassic genus Pachydermophyllum may also have affinities to the peltasperms. [3]
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The morphology of peltasperm leaves is highly variable, ranging from dissected pinnate (fern-like) to forked and simple morphologies. The leaves of many peltasperms have "monocyclic stomata 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 is monophyletic. [2] Some authors have suggested that some peltasperms may have close affinities to corystosperms, another group of extinct "seed ferns". [3] Meyen (1987) argued that Peltaspermales were ancestral to Ginkgoales, due to similarities between certain peltasperm form genera ( Tatarina , Kirjamkenia , Stiphorus , Antevsia) and the extinct gingko Glossophyllum, and grouped peltasperms with Ginkgoales as part of Ginkgoopsida. [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 been insect pollinated, with Pemian members of the long-probiscis scorpionfly family Protomeropidae from Russia associated with peltasperm pollen. The insects are suggested to have fed on pollination drops produced by peltasperm reproductive organs. [11]