Yangopteris ascendens (Halle) gen. et comb. nov., a climbing alethopterid pteridosperm from the Asselian (earliest Permian) Wuda Tuff Flora
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Colleges, School and Institutes
Alethopteris ascendens Halle is an endemic element in the Permian Cathaysian floras and is assumed to be a member of the Medullosales based on its alethopterid type foliage. Previous accounts have documented only its pinnae and bipinnate fronds, but other parts of the plant are unknown. Here we describe new specimens from the earliest Permian (Asselian) Wuda Tuff Flora that are identified as A. ascendens, but shows additional features including an integrated structure comprising an apical hooked prolongation with two lateral rows of hooked spines. Investigation of previously published specimens from another location confirms that they also bore the same kinds of hooked appendages. Systematic comparisons demonstrate that A. ascendens is distinct from previously recognized members of the genus but that it does not conform with the generic diagnosis, leading to the establishment of Yangopteris ascendens gen. et comb. nov. The appendages in Y. ascendens are interpreted as climbing devices, and are most similar to those previously described pteridosperm Karinopteris from the Pennsylvanian of Euramerica. Similarities in the specialized climbing structures in Y. ascendens with alethopterid foliage and Karinopteris with mariopterid foliage suggest ecological convergence in unrelated pteridosperms within late Paleozoic peat-forming swamp ecosystems of Euramerica and Cathaysia. In addition, associated naked axes that co-occur with Y. ascendens are interpreted to be the main stems of the species. The growth habit of Y. ascendens is presumed to be a semi-self-supporting plant but also with a hook-climbing habit, with this similar to modern climbing palms.
|Journal||Review of Palaeobotany and Palynology|
|Early online date||31 Jul 2020|
|Publication status||E-pub ahead of print - 31 Jul 2020|