Ferruginous biofilm preservation of Ediacaran fossils

Ferruginous biofilms are a form of preservation of fossil leaves making detailed imprints of venation even in coarse sandstone. In modern examples, the biofilm is robust enough to persist after separation, or rotting of the leaf. The biofilms are created by filamentous, iron-oxidizing bacteria such as Leptothrix and Sphaerotilus, and have distinctive felted microscopic textures. Ediacaran vendobionts with fine detail preserved in coarse sandstone show these diagnostic felted textures under the scanning electron microscope. These biofilms were thus pre-depositional ferruginous death masks, and lack distinctive framboidal textures or pyritohedral textures of pyrite. Pyritic external-only death masks are undocumented from any geological age or locality. Ediacaran fossils are also preserved by silica permineralization, silica-cemented molds and casts, and pyrite permineralization and replacement after burial. This examination of unskeletonized Ediacaran fossils from Australia, Russia, Namibia, California, and Newfoundland in thin section and scanning electon microscope shows no evidence for a uniquely Ediacaran style of fossil preservation. (C) 2022 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

Automated summary

Ferruginous biofilms are a form of preservation that can retain detailed imprints of venation in fossil leaves even in coarse sandstone. These biofilms, created by filamentous iron-oxidizing bacteria, exhibit distinctive felted textures and are observed in Ediacaran vendobionts. This study finds no evidence for a uniquely Ediacaran style of fossil preservation, suggesting that various preservation methods were used for Ediacaran fossils.