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Maiaspora: ‘hallmark’ of gleichenioid ferns (Gleicheniales) from Early Carboniferousстатья Исследовательская статья
Статья опубликована в высокорейтинговом журнале
Статья опубликована в журнале из списка Web of Science и/или Scopus- Авторы: Mamontov D.A., McLean D., Gavrilova O.A.
- Журнал: PAPERS IN PALAEONTOLOGY
- Номер: IN PRODUCTION
- Год издания: 2024
- DOI: 10.1002/spp2.1561
- Аннотация: The Paleozoic origin of gleichenioid ferns (Gleicheniales) arouses the curiosity sincelast century. The oldest confident sign of this ancient clade was reported from the spore wallultrastructure from the Raditheca dobranyana from the Moscovian of Central Europe. However,family assignment of this fern fossil is uncertain. When comparing these in situ spores and the dispersed genus Maiaspora from Visean, it seems they could be produced by a same group ofleptosporangiates. Although these spores have metareticuloid sculpture in common, the ultrathinstructure of dispersed counterparts remained unknown before. In this contribution, we presentultrastructural details for two species of Maiaspora from Central Russia and Northumberland for the first time: M. concava and M. panopta. Under the TEM, the wall of Maiaspora revealed thatthe middle exospore layer is composed of foliated lamellae spreading from the base of theaperture slit to the subequatorial margins of kyrtome areas. Lamellae do not overlap the aperture slit and terminate at two-thirds or three-fourths of the slit height. The miospores have threelayered exospore at the interradial areas, while non-apertural parts of the exospore consist of two layers. Such an ultrastructure type is shared by Gleicheniales and fossil R. dobranyana. When considering all evidences together from morphology, ultrastructure, and spatiotemporal distribution of Maiaspora, radioisotope dating and additional macroplant fossils, we hypothesized the origin of the Gleicheniales stem related to the closure of the Rheic Ocean. Apparently, the first Maiaspora-producing gleichenioids emerged as neoendemic terrestrial ferns on the volcanic islands in the peri-Gondwanan region.
- Добавил в систему: Мамонтов Дмитрий Аркадьевич