Taphonomy of Permian leaves with Flinders-style Ediacaran preservation

Preservation of unskeletonized Ediacaran vendobionts in red sandstones has been considered unique to that period of geological time, but hundreds of Phanerozoic localities have comparably preserved unskeletonized fossil plants. This study draws taphonomic parallels between Ediacaran vendobiont taphonomy and sedimentology in Flinders Ranges and Nilpena National Parks of South Australia, and seed fern fossils (Evolsonia texana) from the early Permian (Kungurian) Vale Formation, near Lake Abilene, Texas. The seed fern leaves were part of early successional vegetation preserved on weakly developed streamside palaeosols (Fluvents and Psamments), along with the oldest trace fossil evidence of earth worms (Edaphichium lumbricatum). ‘Old elephant skin’ (Rivularites repertus) microbial earth textures, as well as aquatic algal textures (Neantia verrucosa), and adhesion ripples from eolian redeposition were found on the weakly developed palaeosols (Fluvents and Psamments). No fossils were found in moderately developed palaeosols of the Vale Formation (Udepts and Udalfs). The strongly plicated leaves were preserved in three dimensions by ferruginous biofilms from iron oxidizing bacteria, and high relief of the leaves was due to thick veins and robust cuticles. The preservation of Evolsonia texana matches that of Ediacaran Dickinsonia costata from classic South Australian localities, and both are taphonomically unlike any known animal fossils.