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Sponges are the most basal metazoan phylum1 and may have played important roles in modulating the redox architecture of Neoproterozoic oceans2. Although molecular clocks predict that sponges diverged in the Neoproterozoic era3,4, their fossils have not been unequivocally demonstrated before the Cambrian period5–8, possibly because Precambrian sponges were aspiculate and non-biomineralized9. Here we describe a late-Ediacaran fossil, Helicolocellus cantori gen. et sp. nov., from the Dengying Formation (around 551–539 million years ago) of South China. This fossil is reconstructed as a large, stemmed benthic organism with a goblet-shaped body more than 0.4 m in height, with a body wall consisting of at least three orders of nested grids defined by quadrate fields, resembling a Cantor dust fractal pattern. The resulting lattice is interpreted as an organic skeleton comprising orthogonally arranged cruciform elements, architecturally similar to some hexactinellid sponges, although the latter are built with biomineralized spicules. A Bayesian phylogenetic analysis resolves H. cantori as a crown-group sponge related to the Hexactinellida. H. cantori confirms that sponges diverged and existed in the Precambrian as non-biomineralizing animals with an organic skeleton. Considering that siliceous biomineralization may have evolved independently among sponge classes10–13, we question the validity of biomineralized spicules as a necessary criterion for the identification of Precambrian sponge fossils.Cross-hatch impressions from Ediacaran rocks in China are interpreted as having been left by a crown-group sponge fossil, Helicolocellus cantori gen. et sp. nov., characterized by an organic latticework skeleton. [ABSTRACT FROM AUTHOR]

Macrofossils with unambiguous biogenic origin and predating the one-billion-year-old multicellular fossils Bangiomorpha and Proterocladus interpreted as crown-group eukaryotes are quite rare. Horodyskia is one of these few macrofossils, and it extends from the early Mesoproterozoic Era to the terminal Ediacaran Period. The biological interpretation of this enigmatic fossil, however, has been a matter of controversy since its discovery in 1982, largely because there was no evidence for the preservation of organic walls. Here we report new carbonaceous compressions of Horodyskia from the Tonian successions (~950–720 Ma) in North China. The macrofossils herein with bona fide organic walls reinforce the biogenicity of Horodyskia. Aided by the new material, we reconstruct Horodyskia as a colonial organism composed of a chain of organic-walled vesicles that likely represent multinucleated (coenocytic) cells of early eukaryotes. Two species of Horodyskia are differentiated on the basis of vesicle sizes, and their co-existence in the Tonian assemblage provides a link between the Mesoproterozoic (H. moniliformis) and the Ediacaran (H. minor) species. Our study thus provides evidence that eukaryotes have acquired macroscopic size through the combination of coenocytism and colonial multicellularity at least ~1.48 Ga, and highlights an exceptionally long range and morphological stasis of this Proterozoic macrofossils. Carbonaceous compressions of Horodyskia from the Tonian successions reinforce the biogenicity of these macrofossils and indicate that they are among the oldest multicellular and coenocytic macro-organisms. [ABSTRACT FROM AUTHOR]

The origin of motility in bilaterian animals represents an evolutionary innovation that transformed the Earth system. This innovation probably occurred in the late Ediacaran period—as evidenced by an abundance of trace fossils (ichnofossils) dating to this time, which include trails, trackways and burrows1–3. However, with few exceptions4–8, the producers of most of the late Ediacaran ichnofossils are unknown, which has resulted in a disconnection between the body- and trace-fossil records. Here we describe the fossil of a bilaterian of the terminal Ediacaran period (dating to 551–539 million years ago), which we name Yilingia spiciformis (gen. et sp. nov). This body fossil is preserved along with the trail that the animal produced during a death march. Yilingia is an elongate and segmented bilaterian with repetitive and trilobate body units, each of which consists of a central lobe and two posteriorly pointing lateral lobes, indicating body and segment polarity. Yilingia is possibly related to panarthropods or annelids, and sheds light on the origin of segmentation in bilaterians. As one of the few Ediacaran animals demonstrated to have produced long and continuous trails, Yilingia provides insights into the identity of the animals that were responsible for Ediacaran trace fossils. Yilingia spiciformis, a bilaterian dating to the Ediacaran period, is described from body fossils associated with trails produced by the animal, shedding light on the origins of segmentation and motility in bilaterian animals. [ABSTRACT FROM AUTHOR]

Ediacaran successions occur widely in various depositional facies in South China and yield a series of fossil Lagerstätten, providing a complete fossil record for the evolution of marine ecosystems after the terminal Cryogenian global glaciation. Carbonate-dominated Ediacaran successions in shallow water facies in South China record a nearly complete δ13C profile that may reflect variations of marine carbon isotopic composition during the Ediacaran Period. The Ediacaran fossils and δ13C profiles from South China permit stratigraphic correlation and subdivision of the Ediacaran strata. Based on biostratigraphic, chemostratigraphic, and geochronometric data from the Ediacaran successions in South China, we propose that the Ediacaran System in China can be subdivided into two series, with three stages in each series. The lower series is characterized by acanthomorphic acritarchs and the upper series by Ediacara-type macrofossils, and the two series are separated by the declining limb of a pronounced δ13C negative excursion (EN3) in the upper Doushantuo Formation. The basal boundary of Stage 1 is the same as the basal boundary of Ediacaran System, which has been defined at the base of the cap carbonate unit. Stage 2 represents the first radiation of Ediacaran microscopic organisms, with δ13C feature representing by positive values (EP1). The base of the Stage 2 is placed at the first appearance level of a spiny acritarch species. Stage 3 is characterized by the occurrence of more diverse acritarchs and δ13C feature EP2, with its basal boundary defined by a δ13C negative excursion (EN2) occurring in the middle Doushantuo Formation. The basal boundary of Stage 4 is the same as the upper series. Stage 5 is marked by the occurrence of macrfossils of Miaohe biota, and its lower boundary can be placed at the level where δ13C values transition from positive to negative in MNE, or the first appearance level of macrofossils of the Miaohe biota. Stage 6 is characterized by the occurrences of Ediacara-type Shibantan biota and Gaojiashan biota, with its lower boundary defined by the first appearance level of Conotubus hemiannulatus. The formal establishment of the aforementioned series and stages requires further and more detailed integrative stratigraphic study on the Ediacaran successions in China. Some of the Ediacaran successions in South China have great potential to become global standards in Ediacaran subdivision. [ABSTRACT FROM AUTHOR]

Phosphorites of the Ediacaran Doushantuo Formation (∼600 million years old) yield spheroidal microfossils with a palintomic cell cleavage pattern. These fossils have been variously interpreted as sulphur-oxidizing bacteria, unicellular protists, mesomycetozoean-like holozoans, green algae akin to Volvox, and blastula embryos of early metazoans or bilaterian animals. However, their complete life cycle is unknown and it is uncertain whether they had a cellularly differentiated ontogenetic stage, making it difficult to test their various phylogenetic interpretations. Here we describe new spheroidal fossils from black phosphorites of the Doushantuo Formation that have been overlooked in previous studies. These fossils represent later developmental stages of previously published blastula-like fossils, and they show evidence for cell differentiation, germ-soma separation, and programmed cell death. Their complex multicellularity is inconsistent with a phylogenetic affinity with bacteria, unicellular protists, or mesomycetozoean-like holozoans. Available evidence also indicates that the Doushantuo fossils are unlikely crown-group animals or volvocine green algae. We conclude that an affinity with cellularly differentiated multicellular eukaryotes, including stem-group animals or algae, is likely but more data are needed to constrain further the exact phylogenetic affinity of the Doushantuo fossils. [ABSTRACT FROM AUTHOR]

Here is currently little consensus on the branching order and phyletic status of the oldest metazoan groups, but sponges are widely believed to be the earliest-branching living metazoans. Porifera are thought to have diverged before the emergence of developmental characters typical of Eumetazoa, such as well-defined symmetry; extant sponges show radial symmetry of indeterminate high order, or none, combined with polarisation along the axis. In contrast, other early-branching phyla include bilateral and tetraradial (Cnidaria) and biradial (Ctenophora) symmetry, or none (Placozoa). A variety of prismatic early fossil sponges had shown here where the shared symmetry has been overlooked, and also describe structural tetraradial symmetry in Cambrian sponges from South China. Based on this study, this symmetry is likely to have been a primitive feature of sponges, and that the earliest-known fossil sponges were highly organised, cellularly integrated individuals whose body form was under strict genetic control. [ABSTRACT FROM AUTHOR]

The Lantian biota at the Lantian Town of Xiuning County, Anhui Province, is preserved in black shales of the Ediacaran Lantian Formation. It yields some of the oldest known complex macroorganisms, including fan-shaped seaweeds and possible animal fossils with tentacles and intestinal-like structures reminiscent of modern coelenterates and bilaterians. The Lantian Lagerstätte sheds new light on the origin and early evolution of multicellular organisms in relatively quiet and deep environments soon after the Neoproterozoic Marinoan glaciation. The morphological complexity and diversity of early multicellular organisms may be closely related to sexual reproduction and alternation of generations. The fluctuation of oceanic redox conditions during this period may have played a role in the ecology and preservation of the Lantian biota. [ABSTRACT FROM AUTHOR]

The middle Ediacaran Shuram excursion, the largest negative δC excursion in Earth history, has been interpreted as indirect evidence for episodic oxidation and remineralization of deep ocean DOC (dissolved organic carbon). It has been hypothesized that such oxidation event may have occurred when anoxic DOC-laden deep water was brought to shallow shelves during oceanic upwelling, which is expected to cause localized anoxia in shallow environments. To test this prediction, we systematically analyzed rare earth elements (REE) and δC of the upper Doushantuo Formation carbonates in the Yangtze Gorges area of South China, which were deposited in an inner shelf environment and record a large negative δC excursion correlated to the Shuram event. The REE data show a significant positive shift in Ce/Ce* values, synchronous with a pronounced negative δC shift. This positive Ce/Ce* shift is interpreted to represent an oceanic anoxia event in shallow shelf environments, which may have been caused by the upwelling or impingement of oxygen-depleted and C-enriched deep water onto shelves. This anoxia event coincides with a sharp decline in the abundance and diversity of Ediacaran acanthomorphic acritarchs, raising the possibility that these two geobiological events may be causally related. [ABSTRACT FROM AUTHOR]

Palaeoproterozoic global glaciation (∼2.3 Ga) may have been the first 'snowball' Earth event in Earth history. North China has well-exposed sedimentary deposits of this time period with minimal postdepositional alteration. Sedimentary evidence of a glaciation event has been lacking, however. Here we analyzed carbon isotope composition of the Paleoproterozoic Hutuo Group (2.5-2.2 Ga) in the Wutai Mountain area, Shanxi Province, North China. Our data show, in an older to younger chronostratigraphic order, (1) positive δC values in the Dashiling Formation of the Doucun Subgroup (3.2‰ to 1.0‰, VPDB); (2) a decrease in δC values from the Wenshan Formation to the middle Daguandong Formation (from 2.0‰ to-1.2‰), during which time the occurrence of stromatolites declined; (3) a pronounced negative excursion in the upper Daguandong Formation, at the boundary of the Daguandong and Huaiyincun formations (from 1.4‰ to −3.3‰), where stromatolites disappeared; and (4) a gradual increase of δC values in the Beidaxing and Tianpengnao formations (from −1.2‰ to 1.4‰), during which time stromatolites returned. We argue that the negative carbon isotope excursion recorded from the Jian'ancun Formation to the middle Daguandong Formation of the Hutuo Group may have been North China's response to the Palaeoproterozoic global glaciation. [ABSTRACT FROM AUTHOR]

Chuaria is one of the few globally distributed macrofossil pioneers documented in the Precambrian. It is perhaps the most controversial fossil in term of its affinity despite more than one hundred years of study. Many mutually exclusive affinities have been suggested for this frequently encountered fossil. Although often treated as a multicellular alga, this interpretation remains inconclusive because the lacking unambiguous demonstration of cellular structures. In this paper the cellular details of Chuaria are clearly revealed for the first time. The cell walls in Chuaria suggest that it is a multicellular eukaryotic alga, in agreement with the latest biogeochemical analyses. Different thicknesses of cell walls suggest primary cellular differentiation in this organism. Membrane-like structures within the cells (the first to be reported in Precambrian fossils) imply a eukaryotic nature. This study partially resolves the century-long controversy over the affinity of Chuaria, and makes Chuaria one of the few recognized multicellular eukaryotes before the Neoproterozoic glaciation. [ABSTRACT FROM AUTHOR]

Vase-shaped microfossils (VSMs) described herein mainly occur as isolated individuals in thin bedded siltstone and silty carbonate of the Gaojiashan Member of the upper Ediacaran Dengying Formation (ca. 551-541 Ma). Although these fossils are abundant, chained tests or other types of colonial aggregates have not been observed. Specimens in the siltstones can easily be isolated from the host rocks by ultrasonic vibrators. Compared with the co-occurring fossils Gaojiashania and Conotubus, VSMs are rarely pyritized, yet they are always three-dimensionally persevered with little deformation, suggesting that their tests were sturdy and possibly mineralized. Petrological observation and elemental mapping reveal two types of tests that are respectively calcareous and siliceous in composition. Calcareous tests typically consist of two to three crypto-crystal laminae, somewhat resembling bilamellar walls of foraminifers. Siliceous tests consist of fine-grained particles agglutinated with siliceous cement, similar to agglutinated walls of foraminifers. The Gaojiashan VSMs are broadly similar, at least in gross morphology, to the testate amoebae-like VSMs, but their relative large sizes (600-2400 μm) and possibly mineralized (rather than organic) tests argue against this comparison. They also show some similarities to other protozoans, especially tintinnids. However, tintinnids have robust pesudochitinous loricae consisting of both secreted and agglutinated materials. Moreover, tintinnid loricae differ in shape from the Gaojiashan VSM tests in having a constricted aboral end (sometimes with a caudal appendix) and a flaring oral opening. If the Gaojiashan VSMs are indeed related to foraminifers, they indicate that foraminifers were important players in late Ediacaran communities. [ABSTRACT FROM AUTHOR]

Abundant sphaeroidal acritarch Leiosphaeridia asperata, with vesicle size ranging from 13 to 360 μm, occurred in the Proterozoic Liulaobei Formation shales in Huainan, Anhui Province. TEM/SEM studies of these sphaeroidal acritarchs have revealed complex ultrastructures, including ridges, bands, and possible trilaminar structures (TLS). Ridges, spaced ∼1 μm apart, are distributed regularly on the vesicle internal surface of one specimen. Some specimens have alternating electron-dense and electron-tenuous bands that are perpendicular to vesicle walls. Some specimens have trilaminar structures (TLS), while a few others have both bands and TLS. These wall ultrastructures provide evidence that the Liulaobei leiosphaerids are of green microalgae. The variation in wall ultrastructures may represent various stages in a life cycle or developmental phases in the cyst formation analogous to some modern chlorophyceaen microalgae. [ABSTRACT FROM AUTHOR]

Most previously reported Mesoproterozoic (1600-1000 Ma) fossils are from silicified carbonates, and they are commonly small in size (15–20 μm), ranging from coccoids to filaments in morphology. Many of them can be interpreted as cyanobacteria. Carbonaceous shales represent another source of palaeontological information of the Mesoproterozoic biosphere. Sphaeromorphic and acanthomorphic acritarchs, as well as filamentous fossils, are common in many Mesoproterozoic shales. Here we report an unusual assemblage of tubular fossils from the Meosproterozoic Ruyang Group in Shanxi, North China. Some of these tubes are branched. Others bear annular-helical thickening that might be represented by one extinct algae to adapt to a desiccating environment. [ABSTRACT FROM AUTHOR]

Abundant well-preserved large articulated sponge fossils and isolated spicules have been reported from the Early Cambrian Hetang Formation, southern Anhui Province. This unique epifaunal fossil assemblage dominated by articulated sponge fossils is called the Xidi Sponge Fauna. The sponge fauna lived in a quiet oxygenic environment below the storm wave base. Bloom of phytoplankton and rapid sedimentation rate resulted in the deposition of the black shales. Sufficient food supply, lack of other competitors, abundant ecological niches, and demand for oxygen during early Cambrian were in favor of the diversification and evolution of large sponges in the Early Cambrian. [ABSTRACT FROM AUTHOR]

Studies phosphatized biotas from the Neoproterozoic Doushantuo Formation on the Yangtze Platform. Multiple taphonomic windows contained in the cherts, carbonaceous shales and phosphorites onto the late Neoproterzoic biosphere; Clear phophatic window; Preservation of a multitude of single-celled eukaryotes, multicellular algae and microscopic animals.

Investigates the gravity anomaly during the Mohe total solar eclipse in Manchuria, China. Observation of gravity variations; Occurrence of several gravity anomaly valleys; Properties of gravitation.

Examines the structures of Doushantou phosphorites in Guizhou, China. Evolution of multicellular organisms; Coexistence of monaxonal spicules; Detection of fragments of sphaeromorphic acritarchs.

Phosphatized microfossils in the Ediacaran (635–542 Myr ago) Doushantuo Formation, south China, have been interpreted as the embryos of early animals. Despite experimental demonstration that embryos can be preserved, microstructural evidence that the Doushantuo remains are embryonic and an unambiguous record of fossil embryos in Lower Cambrian rocks, questions about the phylogenetic relationships of these fossils remain. Most recently, some researchers have proposed that Doushantuo microfossils may be giant sulphur-oxidizing bacteria comparable to extant Thiomargarita sp. Here we report new observations that provide a test of the bacterial hypothesis. The discovery of embryo-like Doushantuo fossils inside large, highly ornamented organic vesicles (acritarchs) indicates that these organisms were eukaryotic, and most probably early cleavage stage embryos preserved within diapause egg cysts. Large acanthomorphic microfossils of the type observed to contain fossil embryos first appear in rocks just above a 632.5 ± 0.5-Myr-old ash bed, suggesting that at least stem-group animals inhabited shallow seas in the immediate aftermath of global Neoproterozoic glaciation. [ABSTRACT FROM AUTHOR]

Arising from: J. V. Bailey, S. B. Joye, K. M. Kalanetra, B. E. Flood & F. A. Corsetti 445, 198–201 (2007); Bailey et al. replyBailey et al. propose that the Ediacaran microfossils Megasphaera and Parapandorina, previously interpreted as animal resting eggs and blastula embryos, represent Thiomargarita-like sulphide-oxidizing bacteria, claiming that this interpretation better explains their abundance and taphonomy. Here we highlight important observations that significantly weaken the authors' conclusions. [ABSTRACT FROM AUTHOR]

Morphology-based phylogenetic analyses support the monophyly of the Scalidophora (Kinorhyncha, Loricifera, Priapulida) and Nematoida (Nematoda, Nematomorpha), together constituting the monophyletic Cycloneuralia that is the sister group of the Panarthropoda. Kinorhynchs are unique among living cycloneuralians in having a segmented body with repeated cuticular plates, longitudinal muscles, dorsoventral muscles, and ganglia. Molecular clock estimates suggest that kinorhynchs may have diverged in the Ediacaran Period. Remarkably, no kinorhynch fossils have been discovered, in sharp contrast to priapulids and loriciferans that are represented by numerous Cambrian fossils. Here we describe several early Cambrian (~535 million years old) kinorhynch-like fossils, including the new species Eokinorhynchus rarus and two unnamed but related forms. E. rarus has characteristic scalidophoran features, including an introvert with pentaradially arranged hollow scalids. Its trunk bears at least 20 annuli each consisting of numerous small rectangular plates, and is armored with five pairs of large and bilaterally placed sclerites. Its trunk annuli are reminiscent of the epidermis segments of kinorhynchs. A phylogenetic analysis resolves E. rarus as a stem-group kinorhynch. Thus, the fossil record confirms that all three scalidophoran phyla diverged no later than the Cambrian Period. [ABSTRACT FROM AUTHOR]