A zygopterid fern with fertile and vegetative parts in anatomical and compression preservation from the earliest Permian of Inner Mongolia, China

Abstract

Ferns experienced the first of three radiations during the Carboniferous and Permian but most of the resulting groups subsequently became extinct. Many of these fossil taxa are incompletely known because they were preserved and are found as fragments of the former whole-plant, either as petrifactions or compressions. Here we report a new whole-plant species of zygopterid fern with fertile and vegetative parts attached to each other and preserved simultaneously as compressions and petrifactions. This fern grew on peat during earliest Permian times and was preserved in an ashfall tuff together alongside other species from the peat-forming vegetation. The new conceptual whole-plant species is here named Nemejcopteris haiwangii Pšenička et al. sp. nov. Fertile fronds are complex, preserved in three dimensions, and have been found in different developmental stages. Ecologically the species was able to live in nutrient-poor swamp environments but its xeromorphic features will also have allowed it to colonize drier environments. The results of this study together with data from the Czech Republic allow to understand the evolutionary relationships between the genera Corynepteris, Nemejcopteris and Biscalitheca and their foliage.