Sprecher
Beschreibung
Tree ferns dominated the tropical and subtropical forest canopies of the late Carboniferous to early Permian, most belonging to the eusporangiate order Marattiales. However, most Paleozoic tree fern fossils are preserved as isolated organs, such as fragmented pinnae or petrified rachis segments, thereby limiting integrated morphological and anatomical studies. The early Permian Wuda Tuff Flora of Inner Mongolia, China, a T0 fossil Lagerstätte known as the “vegetational Pompeii”, has yielded abundant tree fern fossils, including numerous organically connected specimens bearing both fertile and vegetative organs. Here we describe a new tree fern genus based on such specimens from the Wuda Tuff Flora. The type species possesses tripinnate fronds with pecopterid pinnae. Petioles and pinnae axes bear unicellular trichomes and contain endarch, C-shaped vascular bundles with two laterally involute to revolute ends, representing the stewartiopterid-type configuration characteristic of Marattiales. Fertile pinnae occur on the lower part of fronds, with strongly contracted pinnule laminae. Synangia comprise four sporangia attached to the midvein by a short pedicel, differing from all previously reported marattialean synangia, which are typically borne on lateral veins. Sporangial walls are uniseriate and lack an annulus. Spores are trilete, microechinate, 13–20 μm in diameter. This new genus integrates classic marattialean anatomical features with a leptosporangiate-like uniseriate sporangial wall, representing a mosaic of character states indicative of a transitional lineage. This discovery significantly expands early Permian tree fern diversity and provides crucial evidence for understanding the evolutionary dynamics and morphological innovation among Paleozoic ferns.
Key words: Marattiales, synangium, diversity, transitional lineage