Ecological interactions in Cloudina from the Ediacaran of Brazil: implications for the rise of animal biomineralization

Abstract

At the Ediacaran/Cambrian boundary, ecosystems witnessed an unparalleled biological innovation: the appearance of shelled animals. Here, we report new paleoecological and paleobiological data on Cloudina, which was one of the most abundant shelled animals at the end of the Ediacaran. We report the close association of Cloudina tubes with microbial mat textures as well as organic-rich material, syndepositional calcite and goethite cement between their flanges, thus reinforcing the awareness of metazoan/microorganism interactions at the end of the Ediacaran. The preservation of in situ tubes suggests a great plasticity of substrate utilization, with evidence of different life modes and avoidance behavior. Geochemical analysis revealed walls composed of two secondary laminae and organic sheets. Some walls presented boreholes that are here described as predation marks. Taken together, these data add further information regarding the structuring of shelled animal communities in marine ecosystems.

Discovery of bilaterian-type through-guts in cloudinomorphs from the terminal Ediacaran Period

“…To briefly summarize taphonomy in the Wood Canyon (see also Fig. 7): (i) The initial burial event emplaced the cloudinomorphs within the sulfate reduction zone of the sediment (oriented prone to bedding, whether 34 or not 35 this was their in-vivo position). (ii) Decay by sulfate-reducing bacteria commenced, producing bisulfide that initiated pyrite mineralization.…”

Cuando la vida anduvo errática: Un factor ambiental para la biomineralización de metazoos

“…Erosion of uplifted Ediacaran terrains delivered thick piles of sediments to the oceans, as well as bio-limiting nutrients, especially N, P, and Fe, sulfate, and carbonate alkalinity (as well as Ca 2+ ) released through silicate weathering. Alternatively, the 12 C-rich alkalinity may have built up in anoxic seawater through microbial sulfate reduction promoted by the weathering flux of sulfate to the oceans and a vast reservoir of dissolved organic carbon -although it is the growth of the oceanic Ca 2+ reservoir that most likely promoted This preservational window -suggesting that the organism grew recumbently along the mat surface and thus did not require structural support for orientation in currents -is remarkably similar to that of Cloudina in Ediacaran successions of Brazil (Becker-Kerber et al, 2017). In cross sections of the mounds, it is clear that both metazoans and microbes collaborated in the construction of reefs (contra Mehra & Maloof, 2018).…”

Sedimentary facies, fossil distribution and depositional setting of the late Ediacaran Tamengo Formation (Brazil)

“…11G). They have been described as Cloudina pavements (Becker‐Kerber et al ., 2017) and the spread of shell fragments represents allochthonous bioclasts related to the storm‐wave action (Wood et al ., 2017). The allochthonous bioclasts probably originated from the proximal mid‐ramp setting, and were reworked and transported via the action of storm‐waves and currents.…”

“…1B), the Tamengo Formation comprises black shales, mudstones, wackestones, packstones and grainstones that represent a mixed carbonate–siliciclastic ramp influenced by storm events. The Ediacaran fossil assemblages reported for this unit include Corumbella werneri , Cloudina lucianoi (Zaine & Fairchild, 1987; Grant, 1990; Babcock et al ., 2005; Pacheco et al ., 2011, 2015; Adorno et al ., 2017; Becker‐Kerber et al ., 2017), vendotaenids and conulariids (Van Iten et al ., 2014, 2016), and meiofaunal ichnofossils (Parry et al ., 2017). According to Boggiani et al .…”

“…The presence of low angle to parallel lamination (F5) and hummocky cross‐stratification (F6) provides evidence of reworking by combined oscillatory and unidirectional flow generated by storms (Dott & Bourgeois, 1982; Burchette & Wright, 1992; Demicco & Hardie, 1994; Dumas & Arnott, 2006). Shells of Cloudina with deformational features may be related to transport or compaction (Meira, 2011; Becker‐Kerber et al ., 2017). Thin layers composed of disrupted and flattened clasts of stromatolites (F6) suggest that the reworking of non (or poorly) lithified microbial mats was important (Batten et al ., 2004).…”