中国科学院南京地质古生物研究所机构知识库

Drynarioid ferns comprise a large group in the Polypodiaceae family and are characterised by anastomosing venation and line of abscission between the pinna and the costa. In this paper, after morphological comparison with other ferns, we report and describe a new species,Drynaria diplostichaY. Yu and S. P. Xie, sp. nov. from the upper Miocene sediments of the Bangmai Formation in Lincang City, Yunnan, China. This species is characterised by sori lining the midrib in two rows. The acute curvature of the midrib and the areolae at the base, as well as the slight decurrency, indicate that the fossil was connected to a costa. The occurrence of this fossil suggests that the climate in southwestern Yunnan during the late Miocene was humid and warm with clear seasonality influenced by monsoons which, based on other studies, were weaker than those experienced at present. Given that other Neogene drynarioid fossils (i.e.Drynariacf.propinquafrom the late Miocene andDrynaria callispora,Drynaria dimorpha,Drynaria lanpingensisfrom the late Pliocene) were reported exclusively from western Yunnan, that region might be a radiation centre ofDrynariain the Neogene where its extant species rapidly diversified and the distribution expanded. This may have been driven by the formerly proposed rapid topographic and climatic changes there. TheseDrynariafossils may indicate that western Yunnan was one of the cradles of Drynarioid ferns during their early evolution.