Shaolinopteris gen. nov., a new fern rhizome genus with solenostele from the Jurassic of Northeast China and its palaeogeographic and taxonomic implications

Abstract

China possesses an abundant fossil record of Mesozoic ferns, predominantly preserved as leaf compressions or impressions. In contrast, permineralized fern fossils revealing anatomical details are comparatively rare. Recently, a novel permineralized flora was discovered from the Middle Jurassic Xinmin Formation in Horqin Right Wing Middle Banner, Northeast China, yielding diverse permineralized plant remains. Here, we report a new permineralized fern rhizome genus Shaolinopteris gen. nov. from this flora. The new genus is anatomically characterized by a solenostele with exarch protoxylem, a homogeneous pith, a two-layered rhizome cortex, and “Dennstaedtia-type” adventitious roots featuring diarch protoxylems. Notably, the rhizome inner cortex comprises aerenchymatous columns. Anatomical analysis of Shaolinopteris indicates probable phylogenetic affiliation with the extant fern family Dennstaedtiaceae. Furthermore, a comprehensive revision of the fossil diversity and palaeogeographical distribution of Mesozoic solenostelic fern rhizomes is presented. This new specimen constitutes the first documented occurrence of Mesozoic solenostelic ferns in continental East Asia, providing critical evidence for reconstructing the palaeophytogeography of these taxa.