Rheotropic Epifaunal Growth, Not Felling by Density Currents, Is Responsible for Many Ediacaran Fossil Orientations at Mistaken Point

The assumption that the majority of the Ediacaran fossil taxa on the iconic Mistaken Point E lived erect in the water column underpins inferences concerning: 1) paleoecology of early macrofossil assemblages; 2) how they reproduced; 3) importance of tiering and 4) controls on community dynamics (Mitchell et al., 2015;Mitchell et al., 2019;Mitchell and Butterfield, 2018;Mitchell and Kenchington, 2018).Recent work has cast some doubt on the erect mode of life of some elements of the Mistaken Point biota (namely Beothukis mistakensis, Charnia masoni, Charniodiscus procerus and Gigarimaneta samsoni; McIlroy et al., 2020;McIlroy et al., 2021;Taylor et al., 2021).Careful consideration of morphology, taphonomy and sedimentology have led to the proposal that the fractal-like Rangeomorpha in particular could have harboured sulfur-reducing symbionts and lived as soft sediment recliners (Dufour and McIlroy, 2017;McIlroy et al., 2020, McIlroy et al., 2021).Critical to this type of palaeobiological assessment is determining life attitude.To this end, it has been proposed that-since it seems that rangeomorphs and relatives could feasibly live in the reclining position like Fractofusus-the null hypothesis for interpreting the mode of life of the organisms in this biota should be that they lived as they are found, flat upon the ancient seafloor (McIlroy et al., 2021).This challenge to the Ediacaran palaeobiological community included recommendations for evidence that might be sought to demonstrate an erect mode of life (McIlroy et al., 2021) such as the presence of associated scratch circles (Jensen et al., 2018).Those methodologies have been used to good effect in demonstrating that Charniodiscus concentricus and Arborea spinosus lived with the frond somewhat erect (sediment-parallel recumbent) in the water column, whereas C. procerus was probably a recliner (Pérez-Pindeo et al., 2022). COMPETING TUFFITE DEPOSITIONAL MODELS FOR MISTAKEN POINT E SURFACEThe work of Vixseboxse et al. (2021) aims to demonstrate using orientation data that all of the fronds on the Mistaken Point E surface apart from Fractofusus misrai lived erect in the water column thereby validating all the assumptions in their recent works (Mitchell et al., 2015;Mitchell and Butterfield, 2018;Mitchell and Kenchington, 2018;Mitchell et al., 2019).The iconic images of the E surface with current-aligned fronds have fuelled the idea that the overlying tuffite was deposited from a turbidity current (Benus, 1988;Seilacher, 1999;Matthews et al., 2020).Many authors have also considered that it may have also been a water-lain ash-fall tuff (Anderson and Conway Morris, 1982;Jenkins, 1992;Wood et al., 2003;Bamforth et al., 2008;Brasier et al., 2012).The evidence for tuffite deposition from turbidity currents is

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