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Pteridinium simplex is an iconic erniettomorph taxon best known from late Ediacaran successions in South Australia, Russia, and Namibia. Despite nearly 100 years of study, there remain fundamental questions surrounding the paleobiology and paleoecology of this organism, including its life position relative to the sediment–water interface, and how it fed and functioned within benthic communities. Here, we combine a redescription of specimens housed at the Senckenberg Forschungsinstitut und Naturmuseum Frankfurt with field observations of fossiliferous surfaces, to constrain the life habit of Pteridinium and gain insights into the character of benthic ecosystems shortly before the beginning of the Cambrian. We present paleontological and sedimentological evidence suggesting that Pteridinium was semi-infaunal and lived gregariously in aggregated communities, preferentially adopting an orientation with the long axis perpendicular to the prevailing current direction. Using computational fluid dynamics simulations, we demonstrate that this life habit could plausibly have led to suspended food particles settling within the organism's central cavity. This supports interpretation of Pteridinium as a macroscopic suspension feeder that functioned similarly to the coeval erniettomorph Ernietta, emblematic of a broader paleoecological shift toward benthic suspension-feeding strategies over the course of the latest Ediacaran. Finally, we discuss how this new reconstruction of Pteridinium provides information concerning its potential relationships with extant animal groups and state a case for reconstructing Pteridinium as a colonial metazoan., Copyright © The Author(s), 2022. Published by Cambridge University Press on behalf of The Paleontological Society. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (https://creativecommons.org/ licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited., NHM Repository

The stratigraphic section “Kellwasser-Tal” is the type locality of the Late Devonian Kellwasser Horizons. The locality, which was already badly preserved shortly after its discovery in the middle of the 19 th century by F.A. Roemer, has recently been re-opened and widened. The newly created section ranges from the upper Frasnian to the Lower Carboniferous “Kulm-Kieselschiefer”. Although some parts of the outcrop are highly tectonised it is nonetheless possible to reconstruct the sedimentary sequence. The Kellwasser Horizons, connected to one of the five most severe mass-extinction events in Earth History (Kellwasser Crisis), can now be studied again in detail. Conodonts sampled by O.H. Walliser (Göttingen) in the 1980s as well as new samples were investigated with respect to conodont biostratigraphy and microfacies. The type locality is situated in the European Geopark Harz-Braunschweiger Land-Ostfalen and should be protected as a geosite. Das Profil Kellwasser-Tal (NW-Harz) ist die Typlokalität der oberdevonischen Kellwasser-Horizonte. Die Lokalität, schon bald nach ihrer Entdeckung durch F.A. Roemer Mitte des 19. Jahrhunderts verfallen, ist maschinell erneut freigelegt worden. Es liegt nun ein zusammenhängendes Profil vom höheren Frasnium bis in die Kulm-Kieselschiefer des Unterkarbons vor. Obwohl Teile des Aufschlusses tektonisch sehr stark beansprucht sind, ist die Rekonstruktion der sedimentären Abfolge möglich. Die beiden Kellwasser-Horizonte, zwei isochrone, global nachweisbare Litho-Einheiten (,,Kellwasser-Kalke“), sind wieder gut aufgeschlossen. Sie bezeugen eines der fünf größten Aussterbe-Ereignisse der Erdgeschichte (Kellwasser-Krise). Im Zusammenhang mit den Geländeaktivitäten ist Sammlungsmaterial (Conodontenfaunen, An- und Dünnschliffe) aufgearbeitet worden, so dass der gegenwärtige Bearbeitungsstand der Lokalität dargestellt werden kann. Grundlage der stratigrafischen Bearbeitung waren insbesondere Conodontenproben, welche unter Leitung von O.H. Wall

Thomas Schindler, Michael R.W. Amler, Andreas Braun, Matthias C. Grimm, Winfried Haas, Georg Heumann, Ulrich Jansen, Markus Otto, Markus Poschmann & Eberhard Schindler