First evidence of Ediacaran–Fortunian elliptical body fossils in the Brioverian series of Brittany, NW France

Abstract

Body fossils are described for the first time from the Upper Brioverian (Ediacaran–Fortunian) deposits of Central Brittany (NW France). The material consists of a dozen of specimens preserved on two slates, recently collected in a quarry in Saint‐Gonlay. The fossils, centimetric in size, have an elliptical and acuminated outline, with a peripheral bulge but without conspicuous concentric or radial lines. These body fossils are preserved in slates that are locally rich in grazing traces, sometimes associated with microbial mats. The sedimentological characteristics of these deposits correspond to a shallow marine shelf environment, with a low to moderate hydrodynamism. Such findings, in concomitance with previous ichnological discoveries, unravel the potential of the Brioverian strata from Brittany as a new locality to provide answers on Ediacaran and early Cambrian biocenoses.

New insights into the early evolution of horizontal spiral trace fossils and the age of the Brioverian series (Ediacaran–Cambrian) in Brittany, NW France

“…On a regional scale, the correlation of the Brioverian sedimentary deposits is hindered by the discontinuous cropping out, facies changes, the absence of biostratigraphic markers and the metamorphic overprint from the Devonian-Carboniferous Variscan orogeny (Denis & Dabard, 1988;D'Lemos et al 1990;Le Corre et al 1991;Ballèvre et al 2013). While traditionally interpreted as deeper-marine turbiditic deposits (Dangeard et al 1961;Denis, 1988;Trautmann et al 1999), the Brioverian sedimentary beds also show evidence of shallow-marine storm-influenced (Dabard & Loi, 1998;Dabard & Simon, 2011) and marginal-marine tidally influenced conditions (Graindor, 1957;Dabard, 1990Dabard, , 2000Néraudeau et al 2019).…”

“…Fossils recovered from the Brioverian series are algal or bacterial organic-walled microfossils in cherts and limestones (Cayeux, 1894;Deflandre, 1955;Chauvel & Schopf, 1978;Chauvel & Mansuy, 1981;Mansuy & Vidal, 1983), macroscopic body fossils of unknown origin (Néraudeau et al 2019) and trace fossils. Ichnofossils were first discovered in the late 19th century (Lebesconte, 1886), but did not draw the attention of the scientific community for a long time.…”

“…Despite the report of fossils since the 19th century, the age of its uppermost beds (Ediacaran or early Cambrian) is a long-standing conundrum. Recently, new investigations unravelled a unique assemblage of trace and body fossils in the vicinity of Rennes (Néraudeau et al 2016(Néraudeau et al , 2019Gougeon et al 2018bGougeon et al , 2019. Trace fossils are dominantly simple, horizontal and associated with microbially stabilized surfaces; of these, planispirals represent a surprising discovery.…”

Simple Structures and Complex Stories: Potential Microbially Induced Sedimentary Structures in the Ediacaran Serra De Santa Helena Formation, Bambuí Group, Eastern Brazil

“…6, 7) are preserved exclusively in carbonate and marl facies. Although these discs are superficially similar in size, shape, and relief to Ediacaran macrofossils such as Beltanelliformis (Saint Martin and Saint Martin 2018), Nemiana (Ivantsov et al 2014), and Nimbia (Néraudeau et al 2018), they are more likely to be early diagenetic concretions resulting from differential cementation (Schwid et al 2021). Unlike Beltanelliformis and Nemiana , Type 1 discoidal structures are preserved as positive epirelief features, and do not preserve concentric folds or wrinkles that could indicate the presence of an organic wall (Ivantsov et al 2014).…”

Beltanelliformis brunsaeMennerinKeller, Menner, Stepanov & Chumakov, 1974: an Ediacaran fossil from Neoproterozoic of Dobrogea (Romania)

“…Abundant works were dedicated to the identification and creation of a large number of taxa giving an idea of a fairly large biodiversity of the Ediacaran biota. Nevertheless, the interest of scientific community is naturally focused on the Ediacaran "system" with a particular regard on its palaeoecological significance in the ancient biosphere and its place in the general evolution of life (Shen et al 2008;Xiao & Laflamme 2008;Peterson et al 2008;Liu et al 2010Liu et al , 2015aRetallack 2010Retallack , 2016Serezhnikova 2010;Grazhdankin 2014;Narbonne et al 2014;Antcliffe et al 2015;Droser & Gehling 2015;Tarhan & Laflamme 2015;Dufour & McIlroy 2016;Bowyer et al 2017;Briggs 2017;Budd & Jensen 2017;Reid et al 2017).…”