Abstract
A monospecific flora containing a peltasperm species, Germaropteris martinsii, is discovered from the uppermost Permian Kayitou Formation of Southwest China. The epidermal characteristics of G. martinsii from the South China Block are described for the first time on the basis of charcoalified specimens. The plant is characterised by small, leathery foliage with prominent papillate epidermal cells and slightly sunken stomata. The stomatal apertures are covered by the long papillae of the surrounding subsidiary cells. The specific epidermal traits suggest that G. martinsii is a highly environmentally tolerant taxon that probably formed monospecific communities during the dramatic degradation of the peat-forming rainforest ecosystems. The frequent appearance of charcoalified leaves in the flora demonstrates that intense wildfires were prevalent at the time. The appearance and reflectance value (1.33%) of these charcoalified leaves reveal that they were formed at temperatures of 450–500°C during brief surface fires. Our study indicates that the terrestrial ecosystems may have been frequently subjected to desiccation and was vulnerable to the spread of fires as a result of the end-Permian biotic crisis in the tropics of the eastern Tethys region.
Highlights
Peltasperms are a group of seed plants that have long been considered a typical component of the early Mesozoic vegetation (Taylor et al, 2009)
Samples were treated with 47% hydrofluoric acid (HF) for several days, sieved, washed with diluted water, and prepared for optical and scanning electron microscopy (SEM) investigations
More than 100 Germaropteris martinsii leaves were investigated in this study
Summary
Peltasperms are a group of seed plants that have long been considered a typical component of the early Mesozoic vegetation (Taylor et al, 2009). Because the peltasperms were an exceptionally successful and diverse group that spanned the Permian and Triassic periods, they are important for understanding how plants responded to the end-Permian terrestrial crisis. The fossiliferous Permian–Triassic transitional deposits, including the Xuanwei, Kayitou, and Dongchuan/Feixianguan formations, are exposed extensively in eastern Yunnan and western Guizhou provinces, Southwest China. High-resolution biostratigraphic and geochemical analyses suggest that the Kayitou Formation is a diachronous lithostratigraphic unit ranging from the uppermost Permian to lowermost Triassic (Zhang et al, 2016; Shen et al, 2019). On the basis of detailed field observation across different sedimentological settings, the entire Kayitou Formation has recently been assigned to the uppermost Permian in the terrestrial sections but to the lowermost Triassic in the terrestrial–marine transitional sections (Feng et al, 2020)
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