Whole-plant reconstruction of Scolecopteris libera (Marattiales, Psaroniaceae) from the early Permian of China

Premise of research. Reconstructed whole-plants provide high-quality information on extinct plant species comparable to the morphological and anatomical information available from living plants but are rarely recognized from the fossil record. Based on fossils preserved under a blanket of ash in the earliest Permian aged Wuda Tuff Flora, Inner Mongolia, China, we reconstruct a new whole plant species of marattialean tree fern.

Methodology. The reconstruction is based on anatomical and morphological information including an almost entire fossil tree.

Pivotal results. Scolecopteris libera is reconstructed as an arborescent tree with an apical crown of fronds above a zone of leaf scars from shed fronds. This species has stems of the Psaronius-type, rachises of the stewartiopterid-type, leaf scars of the Caulopteris-type, small aphlebiae, vegetative leaves of the Pecopteris-type, and fertile foliage of the Scolecopteris-type bearing Cyclogranisporites microspores.

Conclusions. Scolecopteris libera represents the most completely reconstructed in-situ preserved Paleozoic marattialean fern and is the first marattialean plant reconstructed from the Wuda Tuff Flora and the Permian Cathaysian floras. Combined with geological information our reconstruction allows us to interpret the S. libera plant as a middle story tree-fern growing in a peat-forming forest that developed on a low-lying delta plain under a humid, tropical climate, therefore occupying the niche and habitat preferred by the majority of extant marattialean tree ferns. Amongst late Paleozoic Marattiales, species of the family Psaroniaceae are distinguished by features of their fertile organs that evolved faster than their more evolutionary conservative vegetative organs including stems, rachises, and leaves.