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Gigantopterids (Gigantopteridales) is the name given to fossils of a group of plants existing in the Late Permian period, some . Gigantopterids were among the most advanced land plants of the Paleozoic Era and disappeared soon after the massive Permian–Triassic extinction event . Though some lineages of these plants managed to persist initially, they either disappeared entirely or adapted radically, evolving into undetermined descendants, as surviving life prospered again in much-altered ecosystems. One hypothesis〔Asama (1982)〕 proposes that at least some "gigantopterids" became the ancestors of angiosperms and/or Bennettitales and/or Caytoniales.〔Miller (2007)〕 Gigantopterid fossils were documented as early as 1883, but only investigated more thoroughly in the early 20th century. Some of their most significant evidence was initially found in Texas, but they might have been present worldwide. Another key region for gigantopterid fossils is in China, and the consolidation of all major continents into Pangea would have allowed for easy global dispersal. They were among the most striking and important plants of the Cathaysian flora of Sino-Malaya, also called ''Gigantopteris'' flora to reflect this.〔Wang (1999)〕 ==Description== They bore many of the traits of flowering plants, but are not known to have flowered themselves. Gigantopterid plants had simple, bilaterally symmetrical leaf structures, woody stems and spines. They grew new parts by producing shoots, like flowering plants. Judging from the fossil remains, they were probably robust plants with fronds that resembled fern fronds when young. When mature they were more like flowering plant leaves with reticulate venation arranged in a frond. ''Gigantopteris nicotianaefolia'' for example is named thus because each of its leaflets resembles a tobacco leaf in shape. They grew at least over 20 cm (around 10 in), probably over 50 cm (20 in) tall, depending on whether it grew as a scrambling vine (the initial assumption) or erect (nowadays considered more likely). Some apparently preferred wetlands, while others throve in rather arid habitat.〔Wang (1999), Glasspool ''et al.'' (2004)〕 The vascular tissue contains vessel elements and in at least some taxa resembles that of the Gnetophyta. They had a cuticula similar to that of other seed plants. Some male sporangia (''Gigantotheca'') and seeds (''Gigantonomia'', ''Cornucarpus'') have been tentatively referred to this group.〔Li & Yao (1983)〕 While the sporangia are certainly not flowers, they differ from other sporangia of Permian plants.〔 Chemical analysis of fossil remains indicates that gigantopterids produced oleananes, chemical compounds otherwise known to be used by flowering plants, for which they function as a suppressant of insect pests. They are apparently also found in certain modern ferns however.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Gigantopterid」の詳細全文を読む スポンサード リンク
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