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A new interpretation of fossilized soils (palaeosols) suggests that at least some Ediacaran (625–542 million years ago) organisms lived on land; thus these Ediacaran fossils were not animals, but a fungus-dominated terrestrial biota that predated vascular plants by about 100 million years. Coming in to land Ediacaran fossils —542 to 635 million years old — occur worldwide in a variety of sedimentary deposits, generally interpreted as shallow to deep marine origin. They have been regarded as early animal ancestors of the Cambrian evolutionary explosion of marine invertebrate phyla, as giant marine protists and as lichenized fungi. Here, Gregory Retallack raises doubts over the assumption that Ediacaran organisms were marine: a new interpretation of fossilized soils ('palaeosols') from South Australia suggests that at least some lived on land. Retallack's suggestion that some Ediacaran fossils were large sessile organisms of cool, dry soils is compatible with observations that Ediacaran fossils are similar in appearance and preservation to lichens and other microbial colonies of biological soil crusts, rather than marine animals or protists. Ediacaran (635–542 million years ago) fossils have been regarded as early animal ancestors of the Cambrian evolutionary explosion of marine invertebrate phyla 1 , as giant marine protists 2 and as lichenized fungi 3 . Recent documentation of palaeosols in the Ediacara Member of the Rawnsley Quartzite of South Australia 4 confirms past interpretations of lagoonal–aeolian deposition based on synsedimentary ferruginization and loessic texture 5 , 6 . Further evidence for palaeosols comes from non-marine facies, dilation cracks, soil nodules, sand crystals, stable isotopic data and mass balance geochemistry 4 . Here I show that the uppermost surfaces of the palaeosols have a variety of fossils in growth position, including Charniodiscus , Dickinsonia , Hallidaya , Parvancorina , Phyllozoon , Praecambridium , Rugoconites , Tribrachidium and ‘old-elephant skin’ (ichnogenus Rivularites 7 ). These fossils were preserved as ferruginous impressions, like plant fossils 8 , and biological soil crusts 9 , 10 of Phanerozoic eon sandy palaeosols. Sand crystals after gypsum 11 and nodules of carbonate 12 are shallow within the palaeosols 4 , even after correcting for burial compaction 13 . Periglacial involutions and modest geochemical differentiation of the palaeosols are evidence of a dry, cold temperate Ediacaran palaeoclimate in South Australia 4 . This new interpretation of some Ediacaran fossils as large sessile organisms of cool, dry soils, is compatible with observations that Ediacaran fossils were similar in appearance and preservation to lichens and other microbial colonies of biological soil crusts 3 , rather than marine animals 1 , or protists 2 .

Charniodiscus is a leaf-shaped Ediacaran (terminal Neoproterozoic) fossil with a worldwide distribution, but the scarcity of complete specimens has previously hindered evaluation of its taxonomy and ecology. The presence of hundreds of complete (fronds with stem and disc attached) Charniodiscus specimens from the Avalon Zone of Newfoundland has allowed for detailed morphometric analysis of Charniodiscus specimens and permits determination of characteristics which vary with growth (e.g., stem length, frond width, and disc diameter) versus those that reflect taxonomic differences (e.g., number of primary segments, presence of a distal spine, shape ratios). This has led to the recognition of three species of Charniodiscus in the Mistaken Point biota, including numerous specimens of two new taxa, C. procerus n. sp. and C. spinosus n. sp., and rare specimens of the Australian species C. arboreus. C. procerus n. sp. and C. spinosus n. sp. represent similar, yet ecologically distinct forms of upper-level filter feeders with diverging feeding strategies in order to reduce the competition for resources. Ratio plots and principal components analyses (PCAs) confirm the existence of five (possibly six) morphologically distinct species of Charniodiscus worldwide.

Impressions of soft-bodied Ediacaran megafossils are common in deep-water slope deposits of the June beds at Sekwi Brook in the Mackenzie Mountains of NW Canada. Two taphonomic assemblages can be recognized. Soles of turbidite beds contain numerous impressions of simple (Aspidella) and tentaculate (Hiemalora, Eoporpita) discs. A specimen of the frond Primocandelabrum is attached to an Aspidella-like holdfast, but most holdfast discs lack any impressions of the leafy fronds to which they were attached, reflecting Fermeuse-style preservation of the basal level of the community. Epifaunal fronds (Beothukis, Charnia, Charniodiscus) and benthic recliners (Fractofusus) were most commonly preserved intrastratally on horizontal parting surfaces within turbidite and contourite beds, reflecting a deep-water example of Nama-style preservation of higher levels in the community. A well-preserved specimen of Namalia significantly extends the known age and environmental range of erniettomorphs into deep-water aphotic settings. Infaunal bilaterian burrows are absent from the June beds despite favorable beds for their preservation. The June beds assemblage is broadly similar in age and environment to deep-water Avalonian assemblages in Newfoundland and England, and like them contains mainly rangeomorph and arboreomorph fossils and apparently lacks dickinsoniomorphs and other clades typical of younger and shallower Ediacaran assemblages. Fossil data presently available imply that the classically deep- and shallow-water taxa of the Ediacara biota had different evolutionary origins and histories, with sessile rangeomorphs and arboreomorphs appearing in deep-water settings approximately 580 million years ago and spreading into shallow-water settings by 555 Ma but dickinsoniomorphs and other iconic clades restricted to shallow-water settings from their first known appearance at 555 Ma until their disappearance prior to the end of the Ediacaran.

Reconstruction and new description of the rare species Charniodiscus yorgensis Borchvardt et Nessov, 1999, which has previously been represented by a single, presently lost specimen, is provided. New material collected in the type locality and closely situated outcrops of Zimnii Bereg of the White Sea allows reconstruction of the structure of this fossil form in more detail. Like other species of the genus Charniodiscus Ford, 1958, the specimen of C. yorgensis , replaced by pyrite initially nonmineralized skeleton of an organism, consisted of a bilobate frond with the rachis passing downwards into the basal disk. It is shown that each lobe of the frond of C. yorgensis was an entire membrane arranged in transverse folds, as an accordion. Plicate lateral lobes, with their free margins directed upwards, adjoin sharp ridges of folds on either side of the membrane. Semipouches formed of bends of lateral lobes were probably the bases of tubular or seedlike elements of branches of the second order, recognized in C. oppositus Jenkins et Gehling, 1978 and C. arboreus (Glaessner, 1959) from Australian localities. Unique records of C. yorgensis buried in an upstanding position corroborate the well-known hypothesis of the vertical lifetime orientation of Charniodiscus .

Fossiliferous Ediacaran successions of South China, the Doushantuo and Dengying formations and their equivalents, are key to understanding bio- and geological evolution at the Neoproterozoic–Cambrian transition. However, their absolute ages, especially the upper Ediacaran successions, are poorly constrained. SIMS zircon U–Pb dating results in this study suggest that ash beds at the basal and middle parts of the Jiucheng Member (middle Dengying Formation) in eastern Yunnan Province were deposited at 553.6 ± 2.7/(3.8) Ma and 546.3 ± 2.7/(3.8) Ma, respectively. These new dates indicate that the age for the base of Dengying Formation in eastern Yunnan Province is similar to the 550.55 ± 0.75 Ma date, which is from an ash bed at the top of the Miaohe Member and has been regarded as the age for the base of Dengying Formation in Yangtze Gorges area. These dates do not permit a clear test of the two correlation models for the chronostratigraphic position of the Miaohe Member (uppermost Doushantuo Formation vs. middle Dengying Formation), implying that further integrated intra-basinal stratigraphic correlations and more high-resolution chronological data from the upper Ediacaran deposits of South China are required. New dates of the Jiucheng Member constrain the age of the fossil biotas in the middle Dengying Formation and extend the stratigraphic range of Rangea, Hiemalora and Charniodiscus to 546.3 ± 2.7/(3.8) Ma. The geochronology of the Dengying Formation implies that Ediacaran-type fossils preserved in this formation are younger than the White Sea Assemblage and temporally overlapping with the Nama Assemblage.

Earth's earliest known metazoan ecosystems are represented by a handful of globally distributed fossil assemblages, collectively referred to as the Ediacara Biota. Although a number of these deposits have been extensively studied, a large proportion of Ediacaran diversity remains uncharacterized. As a result, our understanding of community structure during this important stage of early metazoan evolution is largely incomplete. Moreover, it is only by examining these deposits from a taphonomic perspective that we can hope to decipher these enigmatic forms and fully reconstruct the Ediacaran community. Using this approach, we describe the anomalous preservation of a distinct, prolific, and previously undescribed Ediacaran biogenic sedimentary structure, informally known as “mop,” from the Ediacara Member of the Rawnsley Quartzite in South Australia. Morphological resemblance, spatial association, size distribution, and examination of intermediary forms indicate a shared origin with the holdfast form genus Aspidella and convergence with Pseudorhizostomites. We interpret mop to have been formed by the dragging or uprooting of a Charniodiscus-like frond through a microbially bound substrate by unidirectional currents. Like a freeze frame, mop captures the momentary interaction of organisms and their physical and biotic environment. Detailed characterization of morphological and sedimentological features suggests that variability of mop and associated forms is due largely to taphonomically controlled factors. A better understanding of problematic structures like mop may elucidate the still-enigmatic Ediacaran substrate and the non-actualistic taphonomic processes at work in the preservation of Ediacaran deposits.

We report new high-resolution laser scanning of the type material for the earliest, complex Ediacaran genera Charnia, Bradgatia, Charniodiscus and Ivesheadia from Charnwood, UK, and compare these with Beothukis mistakensis gen. et sp. nov. and the recently described taxa Charnia wardi, Charnia antecedens and Fractofusus spp. from broadly coeval strata in Newfoundland. We use the laser and other techniques to map the similarities and differences in morphology between these Ediacaran rangeomorphs. Key features are suggested to include the number of growth axes, the number and placement of growth tips, the presence of radiating or subparallel axes for the first- and higher-order branches, the extent of displayed or undisplayed leaf-like \"rangeomorph\" architecture, and the extent of furling of the margins of these leaf-like elements. These features are then used to propose suggested homologies between these taxa, leading to a preliminary phylogenetic hypothesis for the evolution of the Avalonian Ediacara biota.

Newly found fossils in the Conception and St. John's groups of the Bonavista Peninsula considerably extend the known geographic distribution of the Ediacaran fossils in Newfoundland. They occur in deepwater sediments and are preserved as epireliefs, forming census populations underneath volcanic ash layers throughout a more than 1 km thick turbiditic sequence. The exposed fossiliferous units comprise the Mistaken Point, Trepassey, Fermeuse, and Renews Head formations. The remains are tectonically deformed, with long axes of elliptical discs aligned parallel to cleavage strike; shortening of originally circular bedding surface features is on the order of 30-50% (averaging ∼35%). The assemblage includes Aspidella, Blackbrookia, Bradgatia, Charnia, Charniodiscus, Fractofusus, Hiemalora, and Ivesheadia. These occur throughout the succession, with Aspidella being the most common genus, followed by Charnia and Charniodiscus. Four new taxa are described, with candelabra-like fossils with a Hiemalora-like base referred to Primocandelabrum hiemaloranum n. gen. and sp., bush-like fossils to Parviscopa bonavistensis n. gen. and sp., ladder-like fossils to Hadryniscala avalonica n. gen. and sp., and string-like fossils with basal disc to Hadrynichorde catalinensis n. gen. and sp. The remains also include dubiofossils. The stratigraphic ranges of some taxa on the Bonavista Peninsula are longer than previously reported from the Avalon Peninsula, with Fractofusus spindles present in the Trepassey Formation, Bradgatia, Charnia, Charniodiscus, and Ivesheadia reaching as high as the Fermeuse Formation, and Aspidella extending into the middle of the Renews Head Formation. The spindles in the Trepassey Formation are comparable to those found mainly in the stratigraphically older Briscal Formation on the Avalon Peninsula.

We propose that some of the more conspicuous Ediacaran fossils from the Avalon Peninsula of Newfoundland, including Aspidella, Charnia, and Charniodiscus, were biologically similar to members of the Kingdom Fungi. These organisms were multicellular or multinuclear, lived below the photic zone, could not move or defoul themselves, did not exhibit taphonomic shrinkage, and were not transported or moved. Aspidella, in particular, appears to exhibit indeterminate growth without a maximum size constraint, and appears to show growth zonations similar to modern mycelia. Other fossils from this deposit exhibit a fractal-like growth pattern. Together, these features falsify algal, lichen, and metazoan interpretations of these fossils, yet reflect characteristics of modern fungal mycelia. We emphasize that although no Mistaken Point fossil appears to be a metazoan, not all of the Mistaken Point taxa, and not all of the Ediacaran organisms in general, can reasonably be interpreted using a fungal analogy. Furthermore, the hypothesis that these fossils were functionally fungus-like need not imply that the organisms were members of the crown-group Fungi. We propose further tests for evaluating both this functional hypothesis and the phylogenetic hypothesis that these organisms were members of the total-group Fungi.

The Mistaken Point and Trepassey formations (Conception and St. John's groups, respectively) comprise a terminal Neoproterozoic, deep-marine succession of fine-grained turbidites and volcanogenic deposits that are part of the Avalonian Terrane. Debris-flow beds, slumped units, the low dispersion of turbidity-current paleoflow directions, and the absence of wave-generated structures together indicate that the sediment was deposited on a deep-water, southeast-facing slope. Channels were not present in the study area. The upward increase in the abundance of slump structures suggests that these units represent toe-of-slope and mid-slope environments, respectively. These units prograded over basin-floor deposits of the Drook and Briscal formations, which have (axial) paleocurrent directions that are orthogonal to the inferred downslope flow that characterized the overlying deposits. Within the Mistaken Point and Trepassey formations, a diverse assemblage of soft-bodied, non-phototrophic Ediacaran organisms is preserved beneath volcanic ash layers on more than one hundred surfaces. Individual fossiliferous surfaces can be correlated up to several kilometres. The felling orientations of frondose fossils indicate that contour currents, as well as up- and downslope currents of tidal and (or) wind-forced origin, influenced the sea floor in the intervals between event beds when the organisms lived. The contour currents may have been responsible for sustaining the organisms in this deep-water setting. The current-produced inclination of the frondose organisms at the time of ash deposition allowed their preservation by preventing the accumulation of ash beneath them.