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The timescale of animal diversification has been a focus of debate over how evolutionary history should be calibrated to geologic time. Molecular clock analyses have invariably estimated a Cryogenian or Tonian origin of animals while unequivocal animal fossils first occur in the Ediacaran. However, redating of key Ediacaran biotas and the discovery of several Ediacaran crown-Metazoa prompt recalibration of molecular clock analyses. We present revised fossil calibrations and use them in molecular clock analyses estimating the timescale of metazoan evolutionary history. Integrating across uncertainties including phylogenetic relationships, clock model, and calibration strategy, we estimate Metazoa to have originated in the early Ediacaran, Eumetazoa in the middle Ediacaran, and Bilateria in the upper Ediacaran, with many crown-phyla originating across the Ediacaran-Cambrian interval or elsewise fully within the Cambrian. These results are in much closer accord with the fossil record, coinciding with marine oxygenation, but they reject a literal reading of the fossil record. [ABSTRACT FROM AUTHOR]

ABSTRACT The lower Nama Group in southern Namibia contains trace fossils and soft‐bodied and biomineralized macro‐organisms from the terminal Ediacaran Period (ca 550 to 539 Ma), offering insights into early metazoan evolution. Interpretation of the fossilized Nama Group organisms as being preserved in, or very close to, the environments in which they originally lived has yielded insights into organism feeding habits, reproduction and life histories. Sedimentological evidence presented here reveals that typical ‘Nama‐type’ Ediacaran macro‐fossils (Cloudina, Ernietta, Pteridinium and Rangea) in the Dabis and Zaris formations of the Witputz Sub‐basin seldom preserve organisms in life position in their original palaeoenvironments. Both soft‐bodied and biomineralizing organisms were transported in sediment gravity flows (debris flows, turbidity flows and transitional debris flow‐turbidity flow ‘hybrid’ event beds) or combined flow (hummocky cross‐strata) to their terminal environment of deposition in shoreface and offshore shelf settings. Transport has placed studied beds and their associated macro‐organisms in depositional settings detached from the original life habitat, with macro‐organisms sourced from shallower‐water, up‐slope environments. Integrated sedimentological and palaeontological data indicate that the Nama Group may not provide a high‐fidelity record of original Nama ecosystems. Individual macro‐organisms are clasts within beds, and can be horizontal, imbricated or chaotic in orientation. Transport can blend different communities at various scales (bed, outcrop and basin), complicating interpretations of life habitats, species interactions and taxon‐specific ecology, such as feeding behaviour and life position of organisms. Recognition of organism transport also impacts datasets used for comparing global Ediacaran fossil assemblages, with implications for tracking spatial and temporal patterns in early animal evolution. [ABSTRACT FROM AUTHOR]

Fossils of the Ediacara Biota preserve the oldest evidence for complex, macroscopic animals. Most are difficult to constrain phylogenetically, however, the presence of rare, derived groups suggests that many more fossils from this period represent extant groups than are currently appreciated. One approach to recognize such early animals is to instead focus on characteristics widespread in animals today, for example multicellularity, motility, and axial polarity. Here, we describe a new taxon, Quaestio simpsonorum gen. et sp. nov. from the Ediacaran of South Australia. Quaestio is reconstructed with a thin external membrane connecting more resilient tissues with anterior‐posterior polarity, left‐right asymmetry and tentative evidence for dorsoventral differentiation. Associated trace fossils indicate an epibenthic and motile lifestyle. Our results suggest that Quaestio was a motile eumetazoan with a body plan not previously recognized in the Ediacaran, including definitive evidence of chirality. This organization, combined with previous evidence for axial patterning in a variety of other Ediacara taxa, demonstrates that metazoan body plans were well established in the Precambrian. [ABSTRACT FROM AUTHOR]

This study focuses on a rare sail-shaped macrofossil, Alienum velamenus gen. & sp. nov. from the Jiangchuan Biota in Yunnan Province, China. The new species presented here possesses an unique bipartite body consisting of a wide unbranched, asymmetrical sail-shaped anterior section and a small narrow tail-like posterior section. The macrofossil of the new species is preserved through carbonaceous compression. Its appearance is different from known macroalgae but similar to Vetulicolia from the early Cambrian Chengjiang Biota. The anterior section of the new species, which is broad and smooth, shows only indistinctly arranged suspected gill slits and a nearly horizontal pharyngeal groove, without significant segmented structures. Owing to lack of samples, the specific biological properties and taxa of the new species are still undefined. The discovery of Alienum velamenus indicates that the Jiangchuan Biota is an exceptional lagerstätte with great potential for the preservation of Precambrian early life through carbonaceous compression. Furthermore, the Jiangchuan Biota shows significant differences in species diversity from the Miaohe Biota of the Doushantuo Formation and the Shibantan Biota of the Dengying Formation in the Three Gorges area of Hubei Province. [ABSTRACT FROM AUTHOR]

The Ediacaran Period is of interest for the emergence of multicellular life, one or more glaciations, and the occurrence of the largest δ13C excursion in Earth history (the Shuram). The Ediacaran stratigraphic succession in the Flinders Ranges of South Australia is distinctive also for well‐exposed outcrop examples of palaeocanyons and salt diapirs. We present data placing a level of salt‐sheet breakout during deposition of the Wonoka Formation, within the time span of the Shuram, and at a datum indistinguishable from the canyon incision level. We hypothesize that canyon incision and salt breakout were triggered by subaerial erosion and non‐deposition associated with sea‐level drawdown in a temporarily isolated embayment. This mechanism provides support for the idea that the palaeocanyons were fluvially incised, and imposes a new constraint on the palaeoenvironmental setting of Australia at the time of the Shuram and the Ediacara fauna. [ABSTRACT FROM AUTHOR]

A time discrepancy of at least 200–300 million years exists between the generally accepted onset of metazoan evolution as currently evidenced from fossils compared with that from studies at the molecular level. That temporal disparity coincides with the existence and subsequent breakup of the Rodinia Supercontinent when the earliest evolutionary crucibles were isolated intracratonic basins rather than the globally connected shallow seaways of subsequent eras. However, the discovery of fossil evidence to complement the extrapolations from molecular data has been, and continues to be, hampered, by both the geographical limitations of these isolated intracratonic basins and the fact that any such discovery would conflict with the global geological mindset that macrofossils of such age do not exist. Yet recently identified within the intracratonic Amadeus Basin of central Australia is a suite of macroscopic metazoan fossils that dates to ca 850–840 Ma, exemplifying an early attempt at animal evolution within the restrictions of the Rodinia Supercontinent. Such early metazoan evolution within such isolated crucibles, however, was extremely vulnerable to variations in climatic conditions, which threatened total extinction because the isolation of these basins limited metazoan distribution by denying them the possibility of migrating to safer havens. The Amadeus Basin evidence suggests that early metazoan evolution perhaps comprised cycles of about 10 million years when evolution flourished followed by climate change induced extinction and a subsequent evolutionary void of between 50 and 100 million years. Such cycles possibly characterised metazoan evolution until the Rodinia Supercontinent broke-up, after which connections between smaller oceans, shallow seas and narrow waterways provided metazoan life passageway to sanctuary during times of environmental stress. As the Amadeus Basin was just one of a number of isolated Rodinian-aged intracratonic basins, it is likely that similar fossils of the earliest metazoans are preserved elsewhere awaiting discovery. KEY POINTS: Metazoan evolution is widely believed to have followed the Gaskiers Glaciation at ca 580 Ma, yet studies at the molecular level suggest evolution began 200–300 million years earlier. Fossils discovered in the Amadeus Basin of central Australia suggest that a diverse metazoan biota had evolved by 850 Ma. Before the Rodinia Supercontinent fragmented during this temporal disparity, intracratonic basins acted as crucibles for early metazoan evolution. Being isolated, intracratonic basins were vulnerable to periodic environmental change causing metazoans, with no means of escape, to periodically become extinct. Amadeus Basin fossils suggest that pre-Ediacaran metazoan evolution possibly comprised cycles of ca 10 million years when evolution flourished before extinction and a following evolutionary void of between 50 and 100 million years. [ABSTRACT FROM AUTHOR]

Burgess Shale-type deposits provide a wealth of information on the early evolution of animals. Questions that are central to understanding the exceptional preservation of these biotas and the paleoenvironments they inhabited may be obscured by the post-depositional alteration due to metamorphism at depth and weathering near the Earth's surface. Among over 50 Cambrian BST biotas, the Chengjiang and Qingjiang deposits are well known for their richness of soft-bodied taxa, fidelity of preservation, and Early Cambrian Age. While alteration via weathering has been well-investigated, the thermal maturity of the units bearing the two biotas has not yet been elucidated. Here we investigate peak metamorphic temperatures of the two deposits using two independent methods. Paleogeotemperature gradient analyses demonstrate that the most fossiliferous sections of the Chengjiang were buried at a maximum depth of ∼8 500 m in the Early Triassic, corresponding to ∼300 °C, while the type area of the Qingjiang biota was buried at a maximum depth of ∼8 700 m in the Early Jurassic, corresponding to ∼240 °C. Raman geothermometer analyses of fossil carbonaceous material demonstrate that peak temperatures varied across localities with different burial depth. The two productive sections of the Chengjiang biota were thermally altered at a peak temperature of approximately 300 °C, and the main locality of the Qingjiang biota experienced a peak temperature of 238 ± 22 °C. These results from two independent methods are concordant. Among BST deposits for which thermal maturity has been documented, the Qingjiang biota is the least thermally mature, and therefore holds promise for enriching our understanding of BST deposits. [ABSTRACT FROM AUTHOR]

The three-dimensional (3D) morphology, anatomy, and in-situ chemical composition analysis of fossils are crucial for systematic paleontology and determining their phylogenetic positions. Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS), offers valuable structural and chemical information for the analysis of fossils. However, its primary limitation is the restriction to two-dimensional surface data, which limits the exploration of fossils' 3D complexities. Conversely, 3D X-ray microscopy (3D-XRM), also known as a novel form of micro-computed tomography (micro-CT) facilitates the non-destructive 3D reconstruction of fossil specimens. Nevertheless, it lacks the capability to provide in-situ compositional data. Acknowledging the constraints inherent in these individual techniques, and in response to the evolving requirements of paleontological research, this study introduces an integrated approach that combines 3D-XRM with EDS-coupled focused ion beam scanning electron microscopy (FIB-SEM). This innovative strategy is designed to synergize the advantages of both techniques, thereby addressing challenges that conventional methods cannot. It enables the rapid identification of regions of interest (ROI) within fossil specimens at micrometer resolution. Subsequently, this method collects detailed data on both 3D structures and chemical compositions at the nanometer scale for the identified ROI. This integrated approach represents a significant advancement in paleontological and geological research methodologies, promising to meet the increasing demands of these fields. [ABSTRACT FROM AUTHOR]

Cnidarians are among the most important diploblastic organisms, elucidating many of the early stages of Metazoan evolution. However, Cnidarian fossils from Cambrian deposits have been rarely documented, mainly due to difficulties in identifying early Cnidarian representatives. Halysites, a tabulate coral from Silurian reef systems, serves as a crucial taxon for interpreting Cambrian cnidarians. Traditionally, the biological characteristics of Halysites have been analyzed using methods limited by pretreatment requirements (destructive testing) and the chamber size capacity of relevant analytical instruments. These constraints often lead to irreversible information loss and inadequate data extraction. This means that, to date, there has been no high-resolution three-dimensional mineralization analysis of Halysites. This study aims to introduce novel, non-destructive techniques to analyze the internal structure and chemical composition of Halysites. Furthermore, it seeks to elucidate the relationship between coral organisms and biomineralization in reef settings and to compare Silurian Tabulata with putative Cambrian cnidarians. Techniques such as micro-X-ray fluorescence spectrometry (micro-XRF), micro-X-ray computed tomography (micro-CT), and scanning electron microscopy (SEM) were employed in this research. With the help of high-resolution micro-CT scanning, we identify the growth pattern of Halysites, showing both lateral and vertical development. The lateral multiple-branching growth pattern of Halysites corals is first established herein. The flaggy corallite at the initial stage of branching is also observed. The micro-XRF mapping results reveal the occurrence of septa spines for Halysites, a trait previously thought rare or absent. Additionally, the ratio of coral volume to the surrounding rock was assessed, revealing that Halysites reefs were relatively sparse (volume ratio = ~30%). The cavities between Halysites likely provided more space for other organisms (e.g., rugose corals and bryozoans) when compared to other coral reef types. Additionally, we provide a comparative analysis of post-Cambrian colonial calcareous skeletons, offering insights into the structural features and growth patterns of early skeletal metazoans across the Ediacaran–Cambrian boundary. [ABSTRACT FROM AUTHOR]

The study of Neoproterozoic carbonate sequences is complicated due to several variables influencing the geochemical and mineralogical composition, compounded by the scarcity of environmental analogs. The Tamengo Formation in the Corumbá Group is one of the most extensively studied archives of the Neoproterozoic in South America and encompasses Ediacaran guide fossils of Corumbella werneri and Cloudina lucianoi. This research focused on a marl sample containing well-preserved bioclasts of exoskeletons of Corumbella werneri, which is one of the earliest biomineralizing organisms. By utilizing diverse techniques such as optical and SEM microscopy, QEMSCAN imaging, electron microprobe, in situ ICP-MS, and isotope analyses, this study reveals primary and secondary signals in the bioclastic exoskeletons and the matrix within. These findings shed light on the sedimentary environment and diagenetic history of the Tamengo Formation. It is revealed that Corumbella werneri likely inhabited calm conditions, just below the base of storm waves and above a sharp chemocline at the bottom. In addition, the presence of distinct hydrothermal signals in the composition of REEs indicates a potential magmatic event that occurred in the region after the deposition of the succession. This pilot study highlights that the history recorded in the Neoproterozoic rocks of the Tamengo Formation is complex, and thus more detailed studies integrating lithological, paleontological, and geochemical parameters are necessary to reach a correct interpretation of this sequence. [ABSTRACT FROM AUTHOR]

Elongated biconvex Carex fossil fruits are relatively common in fossil assemblages, but they are of much uncertain taxonomic affinity. Three fossil-species have been erected to accommodate the materials from the respective type localities (C. klarae, C. paucifloriformis and C. paucifloroides) and a number of superficially similar-looking fossils were reported from other sites. The formerly proposed affinities mostly pointed to the extant C. pauciflora (subgen. Euthyceras) or Carex sect. Cyperoideae (subgen. Vignea), depending on the authors. But despite the similar superficial resemblance of the fossil remains to these not very closely related sedge taxa, other groups are also possible matches. We used a comparative approach employing stereomicroscope and SEM to analyze the affinities of several Old World "mummified" fossils (ca. 23 to 0.1 Ma) of elongated biconvex fruits. Several samples showed a fair preservation of previously unattested microscopic characters. In particular, one of them allowed us to detect an indirect record of fine silica body morphologies (impressions) on the periclinal walls, which permitted the sound taxonomic placement of the remains from the Miocene of Siberia as a Carex sect. Cyperoideae. In all the other fossils analyzed, the epidermal cell outline and the central position of the main silica body were sufficient to discard assignment to subgen. Euthyceras, despite a purported affinity to C. pauciflora reported in previous literature. In the absence of detailed information on silica bodies, epidermal cell (exocarp) details in fossil specimens do not seem to be determinant for the systematic placement. However, the addition of diagnostic style characters pointed to sect. Cyperoideae as the best match with the available information. Our data support a continued presence of Carex sect. Cyperoideae in the Old World since the Miocene, which candidates Eurasia as a possible place of origin for it, despite DNA-based reconstructions alone proposed North America. This study underlines the importance of detailed taxonomic studies to properly address the identity of fossils and unravel the biogeographic history of plants. [ABSTRACT FROM AUTHOR]

Somatic design is crucial for soft grippers to emulate the embodied intelligence of their biological counterparts, due to the blurry boundaries among material, structure, and function. There are five critical parts in somatic design, including morphology, material, fabrication, actuation, and variable stiffness. The strong nonlinear coupling among these factors often leads to mutual influence and functional compromise after integration. Herein, methods and strategies harnessed in these parts for performance improvement of soft grippers are systematically reviewed, particularly clarifying how to exert the coupling enhancement effects of the somatic parts for functional synergy. Finally, the remaining challenges and the future development directions of soft grippers for organism‐like intelligence and wide‐range applications are discussed. [ABSTRACT FROM AUTHOR]

Autotrophic microaerophilic iron-oxidizing Zetaproteobacteria seem to play an important role in mineral weathering and metal corrosion in different environments. Here, we compare the bacterial and zetaproteobacterial communities of a mature iron-rich mat together with in situ incubations of different Fe-bearing materials at the EMSO-Ligure West seafloor observatory, which is located on the abyssal plain in the NW Mediterranean Sea. Our results on bacterial communities enable us to make a clear distinction between those growing on mild steel anthropic substrata and those developing on basaltic substrata. Moreover, on anthropic substrata we highlight an influence of mat age on the bacterial communities. Regarding zetaproteobacterial communities, our results point to an increase in ZetaOTUs abundance and diversification with the age of the mat. We corroborate the key role of the ZetaOTU 2 in mat construction, whatever the environment, the substrata on which they develop or the age of the mat. We also show that ZetaOTU 28 is specific to anthropogenic substrata. Finally, we demonstrate the advantage of using dPCR to precisely quantify very low abundant targets, as Zetaproteobacteria on our colonizers. Our study, also, allows to enrich our knowledge on the biogeography of Zetaproteobacteria, by adding new information on this class and their role in the Mediterranean Sea. [ABSTRACT FROM AUTHOR]

The present study reports the well-preserved Ediacaran sack-like soft-bodied fossils assigned as Finkoella ukrainica and Finkoella oblonga from the Sonia Formation of the Jodhpur Group, Marwar Supergroup, western Rajasthan, India. The F. ukrainica is found in elliptical, ovate-shaped and sometimes oblong or cucumber-shaped forms with a distinct short neck, and a small circular protrusion or depression may be present on the organism. F. oblonga is elongated, ovate to cucumber-shaped fossil specimen with poorly preserved six longitudinal low grooves and ridges arranged parallel to the marginal ridges of the organism. Both F. ukrainica and F. oblonga are also well comparable to the type materials of Ukraine in the preservation of concave (negative relief) and convex (positive relief) with oral/atrial siphons, double marginal ridges/grooves and elevated edges in the Sonia Formation. The Finkoella fossil remains are believed to be the flattened bodies of tunicate organisms. Similar sack-shaped Burykhia fossils recorded in the White Sea of Russia contrasted to sponges and similar hollow-shaped organisms have been interpreted and compared with lichenized fungi and fungal affinity. Thus, the biological affinity of the Finkoella organism is still unresolved. [ABSTRACT FROM AUTHOR]

This article provides information on the trilobite Eldredgeops (Phacops) rana, which lived around 390 million years ago in Ohio and surrounding areas. The trilobite was originally classified as Phacops but is now known as Eldredgeops, although the name Phacops is still commonly used. The article focuses on three locations where the trilobite can be found: two commercial rock quarries in Ohio and a fossil park in New York. While the Ohio quarries no longer allow collecting, the fossil park in Ohio is still open to collectors. The article describes the characteristics of the trilobite and the fossils found in the Silica Shale formation, including brachiopods, corals, and early fish. It also mentions the differences in color between the trilobite specimens found in the Ohio quarries. The article concludes by highlighting two fossil parks in New York State where visitors can collect fossils, particularly trilobites. The Fossil Park in Sylvania is open to the public for free and has received positive reviews. The Penn Dixie Fossil Park in Hamburg is a popular destination for fossil collectors and offers opportunities for surface collecting and digging in situ. Visitors are advised to come prepared with sunscreen, hats, and drinking water. The article encourages readers interested in finding their own trilobite fossils to explore these collecting sites. [Extracted from the article]

Prospecting fieldwork in a new fossiliferous locality of the marine Early Miocene Gaiman Formation (Patagonia, Argentina) results in the discovery of abundant fossil cetaceans (n = 29). We analyse stratigraphic, sedimentologic, palaeontologic, and taphonomic data with the aim of understanding the factors that control the preservation and distribution of these specimens. The cetacean sample is dominated by small odontocetes exhibiting five different preservation categories. Based on sedimentological features, three distinct facies were recognised in the stratigraphic section. Stratigraphically condensed deposits of facies C, related to a ravinement surface and subsequent transgressive deposits, enclose 52% of the specimens, grading from isolated postcranial elements to articulated and associated postcranial and cranial elements. In contrast, facies A and B exhibit predominantly isolated postcranial elements. Facies C shows higher degrees of corrosion, encrustation and fragmentation than those specimens from facies A and B, reflecting differences in preservation quality among the facies. The higher abundance and evidence of long exposure times recorded for facies C seems to be resulted mostly from physico-chemical factors after stratigraphic condensation. Finally, intrinsic biological features and ecological preferences of the specimens could explain the dominance of small-sized odontocetes in a restricted inner shelf to lower shoreface environmental setting. [ABSTRACT FROM AUTHOR]

The potential carcinogenicity of talc has been evaluated in many studies in humans and experimental animals published in the scientific literature over the last several decades, with a number of these studies reporting no associations between talc exposure and any type of cancer. In order to fully understand the current state of the science regarding the potential for talc to induce human cancers, we conducted a comprehensive and systematic review of the available experimental animal and mechanistic evidence (in conjunction with a systematic review of the epidemiology evidence in a companion analysis) to evaluate whether it supports talc as being carcinogenic to humans. We considered study quality and its impact on the interpretation of results and evaluated all types of cancer and all exposure routes. We also evaluated the evidence on the potential for talc to migrate in the body to potential tumor sites. We identified seven experimental animal carcinogenicity studies and 11 mechanistic studies of talc to systematically review. We found that several of the experimental animal carcinogenicity studies of talc have limitations that preclude their sensitivity to detect increases in tumor incidence. Regardless, the studies cover multiple exposure routes, species, and exposure durations, and none indicate that talc is a carcinogen in experimental animals except in rats under conditions of extremely high exposure that likely resulted in lung particle overload, a nonspecific effect of high exposures to poorly soluble particles, and not from any carcinogenic properties of talc. Lung particle overload leading to lung tumor formation has only been observed in rats and not in any other species, including humans. The mechanistic studies indicate that talc is not genotoxic or mutagenic, but can induce some effects that could be events on a possible pathway to carcinogenicity, mainly at high exposures or in in vitro studies with exposures of unclear relevance in vivo, but these effects are not consistent across studies and cell types. This systematic review of the experimental animal carcinogenicity and mechanistic evidence for talc indicates that an association between talc exposure and cancer is not expected in humans. Talc carcinogenicity is not plausible in any species except rats, and only when the exposure conditions are high enough to induce lung particle overload, which is not relevant to human exposures. [ABSTRACT FROM AUTHOR]

Apart from within the Arumbera Sandstone that spans the Ediacaran–Cambrian boundary, the entire Neoproterozoic succession of the Amadeus Basin has been generally believed to be devoid of metazoan fossils, despite features of possible biogenic origin having been described in the earliest geological mapping reports. Herein are described a suite of curious, rounded impressions preserved upon the surface of a sandstone bed from the basal Neoproterozoic unit, the quartzitic Heavitree Formation that dates to ca 850 Ma. Compared with rounded structures of both organic and inorganic origin, these features resemble fossils of stranded medusae, both modern and ancient, and thereby add a potentially pelagic lifeform to previously described burrowing and sessile forms of likely metazoans, which are preserved as fossils/trace fossils within the Tonian period of the Neoproterozoic elsewhere in the basin. An organic origin for these features would support the contention that the Amadeus Basin harbours the earliest evidence that macroscopic life flourished, albeit briefly, some 215 million years prior to the start of the Ediacaran period and 250 million years before metazoans successfully colonised the late Ediacaran seas. Curious rounded impressions upon a scree sample of Heavitree Formation (ca 850 Ma) are best compared with fossils of stranded jellyfish, both modern and ancient. Such impressions add to the phyla seemingly extant within the Amadeus Basin during the Tonian Period (early Neoproterozoic). Such phyla suggest that metazoan life evolved some 250 Ma earlier than generally believed, although became extinct locally some 10 Ma later. Extinction occurred at ca 840 Ma when changing climate caused the enclosed Amadeus Basin to evolve from conducive shallow aquatic conditions to a harsh evaporitic salt pan. Two later forays into metazoan evolution within the basin are evidenced by burrow-like tubular structures at ca 720 Ma and the Arumberia fossils at ca 560 Ma. [ABSTRACT FROM AUTHOR]

The early Ediacaran Weng'an biota (Doushantuo Formation, South China) provides a rare window onto the period of Earth history in which molecular timescales have inferred the initial phase of crown-metazoan diversification. Interpretation of the embryo-like fossils that dominate the biota remains contentious because they are morphologically simple and so difficult to constrain phylogenetically. Spiralicellula from the Weng'an biota is distinguished by spiral internal bodies, allied through development to Megasphaera or Helicoforamina and interpreted variously as metazoan embryos, encysting protists, or chlorophycean green algae. Here we show, using X-ray microtomography, that Spiralicellula has a single-layered outer envelope and no more than 32 internal cells, often preserving a nucleus and yolk granules. There is no correlation between the extent of spiral development and the number of component cells; rather, the spiral developed with each palintomic stage, associated with cell disaggregation and reorientation. Evidence for envelope thinning and cell loss was observed in all developmental stages, reflecting non-deterministic shedding of gametes or amoebae. The developmental biology of Spiralicellula is similar to Megasphaera and Helicoforamina, which otherwise exhibit more rounds of palintomy. We reject a crown-metazoan affinity for Spiralicellula and all other components of the Weng'an biota, diminishing the probability of crown-metazoan diversification before the early Ediacaran. [ABSTRACT FROM AUTHOR]

The beginning of the Phanerozoic saw two biological events that set the stage for all life that was to come: (a) the Cambrian Explosion (the appearance of most marine invertebrate phyla) and (b) the Great Ordovician Biodiversification Event (GOBE), the subsequent substantial accumulation of marine biodiversity. Here, we examine the current state of understanding of marine environments and ecosystems from the late Ediacaran through the Early Ordovician, which spans this biologically important interval. Through a compilation and review of the existing geochemical, mineralogical, sedimentological, and fossil records, we argue that this interval was one of sustained low and variable marine oxygen levels that both led to animal extinction and fostered biodiversification events throughout the Cambrian and Early Ordovician. Therefore, marine ecosystems of this interval existed on the edge—with enough oxygen to sustain them but with the perennial risk of environmental stressors that could overwhelm them. We review the current research on geochemistry and paleontology of the Cambrian and Early Ordovician periods. Low and oscillating oxygen levels in the marine realm promoted diversification and evolutionary innovation but also drove several extinction events. Taphonomic modes and marine authigenic pathways that were abundant in the Cambrian were supported by oceans that were persistently less oxygenated than today's oceans. [ABSTRACT FROM AUTHOR]

Ediacara‐type macrofossils appear as early as ~575 Ma in deep‐water facies of the Drook Formation of the Avalon Peninsula, Newfoundland, and the Nadaleen Formation of Yukon and Northwest Territories, Canada. Our ability to assess whether a deep‐water origination of the Ediacara biota is a genuine reflection of evolutionary succession, an artifact of an incomplete stratigraphic record, or a bathymetrically controlled biotope is limited by a lack of geochronological constraints and detailed shelf‐to‐slope transects of Ediacaran continental margins. The Ediacaran Rackla Group of the Wernecke Mountains, NW Canada, represents an ideal shelf‐to‐slope depositional system to understand the spatiotemporal and environmental context of Ediacara‐type organisms' stratigraphic occurrence. New sedimentological and paleontological data presented herein from the Wernecke Mountains establish a stratigraphic framework relating shelfal strata in the Goz/Corn Creek area to lower slope deposits in the Nadaleen River area. We report new discoveries of numerous Aspidella hold‐fast discs, indicative of frondose Ediacara organisms, from deep‐water slope deposits of the Nadaleen Formation stratigraphically below the Shuram carbon isotope excursion (CIE) in the Nadaleen River area. Such fossils are notably absent in coeval shallow‐water strata in the Goz/Corn Creek region despite appropriate facies for potential preservation. The presence of pre‐Shuram CIE Ediacara‐type fossils occurring only in deep‐water facies within a basin that has equivalent well‐preserved shallow‐water facies provides the first stratigraphic paleobiological support for a deep‐water origination of the Ediacara biota. In contrast, new occurrences of Ediacara‐type fossils (including juvenile fronds, Beltanelliformis, Aspidella, annulated tubes, and multiple ichnotaxa) are found above the Shuram CIE in both deep‐ and shallow‐water deposits of the Blueflower Formation. Given existing age constraints on the Shuram CIE, it appears that Ediacaran organisms may have originated in the deeper ocean and lived there for up to ~15 million years before migrating into shelfal environments in the terminal Ediacaran. This indicates unique ecophysiological constraints likely shaped the initial habitat preference and later environmental expansion of the Ediacara biota. [ABSTRACT FROM AUTHOR]

The Qinghai-Tibetan Plateau and its surrounding areas have a long and complex tectonic evolutionary history. Cratons and blocks, such as northern India, Lhasa, Qiangtang, Qaidam and Central Qilian, and their in-between orogenic belts constitute the main part of the Qinghai-Tibetan Plateau. During the Cambrian Period, most of these cratons and blocks were on the northwestern periphery of Gondwana, and were associated with the surrounding blocks, e.g. Arabian, Central Iran, Afghanistan, Tarim, Alxa, North China, South China and Sibumasu through the Proto-Tethys Ocean. The Cambrian stratigraphic sequences on these stable blocks are composed of mixed siliciclastic and carbonate rocks deposited in the shallow-water marine environments, and contain the trilobite assemblages of shelf facies. The Cambrian stratigraphic sequences in the Qilian tectonic belts, however, are characterized by the intermediate-basic igneous rocks and silicates formed in the Proto-Tethys Ocean, and contain the trilobite assemblages of deep-water slope facies. Combining with previous data, field observations and newly discovered fossils through funding by the Second Tibetan Plateau Scientific Expedition and Research, the general characteristics of the Cambrian strata in different tectonic units of the Qinghai-Tibetan Plateau and its surrounding areas have been summarized in this paper. Furthermore, efforts have been made to subdivide and correlate the Cambrian strata across these areas by utilizing available biostratigraphic and geochronological data. As a result, a comprehensive litho- and biostratigraphy chart has been compiled. Finally, from the biogeographic perspective, this paper also provides a brief overview of the Cambrian paleogeographical reconstruction of the major tectonic blocks, and discusses the problems associated with the evolution of the Proto-Tethys tectonic belt. [ABSTRACT FROM AUTHOR]

The Ordovician rocks on the Qinghai-Tibetan Plateau represent the oldest non-metamorphic strata, and are critical to understanding the history of regional geology and biotic evolution of the entire plateau. Strata of Floian, Darriwilian, Sandbian, Katian and Hirnantian are represented in the plateau with a hiatus of variable duration occurring underneath the basal Ordovician across the area. Five stratigraphical regions, including the Himalaya, Gangdise-Zayu, Qiangtang-Qamdo, Songpan-Garze, and Karakoram-Kunlun-Altun, are differentiated for the Ordovician strata, which are correlated with their equivalents in the Sibumasu, Indochina, Qaidam-Qilian, Tarim-Tianshan, and the Yangtze (western margin) stratigraphical regions. On the Qinghai-Tibetan Plateau, graptolites, conodonts, and cephalopods are the most common and useful fossils for the Ordovician biostratigraphy. The Ordovician biotas of the Qinghai-Tibetan Plateau bear some distinguishable palaeobiogeographical signatures, among which the cephalopods are characterized by the flourishing actinocerids of North China affinity in the Early-Middle Ordovician, and by the thriving lituitids and orthocerids of South China affinity in the Middle-Late Ordovician. Fossil occurrences and their palaeobiogeographical evolution provide critical evidence bearing on the reconstruction of the geological history of the Qinghai-Tibetan Plateau and surrounding terranes in northeastern peri-Gondwana. The stratigraphical successions of the Cambrian-Ordovician transition in the Himalaya and Lhasa and nearby Sibumasu terranes were significantly affected by the Kurgiakh Orogeny, which resulted in the extensive unconformity between the Ordovician and the underlying rocks in most areas of the Qinghai-Tibetan Plateau. In southern Xizang, a warm-water biota of Middle Ordovician age was recovered from oolitic limestones, suggesting a likely palaeogeographical location in low-latitudes near the equator. In the Himalaya and Sibumasu regions, the Upper Ordovician was typified by the occurrence of red carbonates with distinctive reticulate structures, which are correlative to their equivalents in the Yangtze region of South China, and might be deposited under similar geological conditions. The global end-Ordovician glaciation and sea-level drop likely caused the wide absence of late Katian strata in western Yunnan of China and the Shan State of Myanma, and may have also affected deposition in the Xainza and Nyalam areas of the Qinghai-Tibetan Plateau during this time interval. [ABSTRACT FROM AUTHOR]

The complex evolutionary history of the Qinghai-Tibetan Plateau and its surrounding areas, including the continental blocks (Indian, Lhasa, South Qiangtang, Tarim, Olongbuluk, Central Qilian, Alxa, North China, Yangtze, Central Iran and Oman) and the orogenic belts between them, has long been the frontier in Earth science research. The Cryogenian and Ediacaran strata are extensively distributed in these blocks. Specifically, relatively complete Cryogenian and Ediacaran successions have been discovered in Oman, Indian, Yangtze, and Tarim blocks, while only the Ediacaran successions have been reported in Iran, the South Qiangtang, Central Qilian, Alxa, and North China blocks. Based on previous studies together with the integration of new materials and advancement obtained through the Second Tibetan Plateau Scientific Expedition and Research, this review aims to synthesize a correlative stratigraphic framework of the representative Cryogenian and Ediacaran sequences from the Qinghai-Tibetan Plateau and its surrounding areas. Furthermore, the Cryogenian and Ediacaran biotas and major geological events in these areas are comprehensively discussed in aspects of current research status. The results indicate that, in general, Ediacaran fossils of each area exhibit distinct features in preservation and assemblage composition, but the typical late Ediacaran fossils Cloudina and Shaanxilithes have been reported from most of these areas. In addition to the two global Cryogenian glaciations, late Ediacaran glaciogenic deposits are extensively recorded in the areas within and around the northern Qinghai-Tibetan Plateau (including the North China, Alxa, Central Qilian, Olongbuluk, and Tarim blocks, and the North Qilian Accretionary Belt), as well as central and southern Iran. However, further research is required to determine the age, distribution, and origin of these late Ediacaran glaciogenic deposits. Meanwhile, the middle Ediacaran DOUNCE/Shuram Excursion is widely documented in the Qinghai-Tibetan Plateau and its surrounding areas. The available data show that, after the break-up of the Rodinia supercontinent, most of the continental blocks in the areas were located along the northern margin of East Gondwana and a few (such as North China) were located between the Gondwana and Laurentia. In general, the paleogeographic evolution of most of these blocks during the Cryogenian and Ediacaran remains disputatious, necessitating further research to resolve the controversies surrounding their paleogeographic reconstruction models during this critical time interval. [ABSTRACT FROM AUTHOR]

During the Carboniferous Period, the Qinghai-Tibetan Plateau and its surrounding areas were located in quite different paleogeographic positions with various sedimentary and biological types. It is important to systematically compile and summarize the Carboniferous strata and biotas of the Qinghai-Tibetan Plateau and its surrounding areas, to establish an integrated stratigraphic framework for correlation, and to reconstruct the paleogeography for correctly understanding the breakup of the Gondwana Continent and the evolution of the Paleo-Tethys Ocean in the Late Paleozoic. The Carboniferous of the Qinghai-Tibetan Plateau and its surrounding areas can be subdivided into the Gondwanan, Cimmerian, and Tethyan types. The Gondwanan-type Carboniferous are distributed in the North Himalayan, Kangmar-Lhunze, and Zanda-Zumba regions of the South Tibet Subprovince and northern India-Pakistan Area, where only the Mississippian is developed and the biota is of Gondwanan affinity. The Cimmerian-type Carboniferous, which are found in the Baoshan, Tengchong, Coqen-Xainza, Lhasa-Zayu, Nagqu-Biru, and South Qiangtang regions, as well as Shan-Thai and South Afghanistan-Pamir areas, also represent only the Mississippian strata, but their biota is characterized by mixed characters of European, South China, Australian, and North American types. The Tethyan-type Carboniferous are distributed in the Tanggula Mountains, Hoh Xil-Bayanhar, Chamdo-Hengduanshan, Tiekelike, West Kunlun, Karakorum, East Kunlun-Central Qinling, and Qilian regions, where the Carboniferous succession is well developed, and the biota is of warm-water Tethyan affinity. The biostratigraphical correlation of the Gond-wanan-type and Cimmerian-type Carboniferous is based mainly on conodonts and additionally on brachiopods and rugose corals. The Mississippian of the Tethyan-type Carboniferous is correlated mainly by using rugose corals and brachiopods, whereas in the Pennsylvanian foraminifera (fusuline) and conodonts are regarded as primary fossil groups, subordinated by rugose corals and brachiopods. Adhering to the International standard chronostratigraphy of the Carboniferous, we have reconstructed a framework of the litho- and biostratigraphic subdivision and correlation of the Qinghai-Tibetan Plateau and its surrounding areas. Further studies should focus on isotope geochronology, geochemistry, paleoclimates, and paleoenvironments of the Carboniferous in the Qinghai-Tibetan Plateau and its surrounding areas. [ABSTRACT FROM AUTHOR]

The Jiangchuan Biota from the Jiucheng Member (Mb.) of the Dengying Formation (Fm.), discovered in Jiangchuan, eastern Yunnan, China, is marked by copious macrofossils at the apex of the Ediacaran strata. This fauna features benthic algae with varied holdfasts and other fossils of indeterminate taxonomic affinity and is compositionally unique compared to the Shibantan and Gaojiashan biotas of the Dengying Fm. and the Miaohe and Wenghui biotas of the Doushantuo Fm., elsewhere in China. One novel benthic saccular macroalgal fossil, named here Houjiashania yuxiensis gen. and sp. nov., from the Jiangchuan Biota is based on fossils that are sausage‐shaped, elongate, tubular, ranging from 0.3 to 4 cm in length, and up to 0.8 cm in diameter. One terminus is blunt and rounded to an obtuse angle, the other is bent with a spread‐out surface resembling a holdfast, suggesting a three‐dimensional thallus. Thin, stipe‐shaped outgrowths, likely vestiges of sessile saccular life forms, are prevalent in macroalgal fossils of analogous size and shape, as well as present brown algae Scytosiphonaceae, such as Colpomenia and Dactylosiphon. The new findings augment the diversity of benthic algae, such as those known from the Early Neoproterozoic Longfengshan Biota in North China. The benthic algal macrofossils in the Jiucheng Mb. add to knowledge of Late Ediacaran metaphyte diversification and offer more clues about the evolutionary positioning of primitive macroalgae. The co‐occurrence of numerous planktonic and benthic multicellular algae and planktonic microbes might have facilitated ecologically the more extensive later Cambrian explosion evidenced by the Chengjiang Biota in Yunnan. [ABSTRACT FROM AUTHOR]

High‐sulfur, low‐oxygen environments formed by underwater sinkholes and springs create unique habitats populated by microbial mat communities. To explore the diversity and biogeography of these mats, samples were collected from three sites in Alpena, Michigan, one site in Monroe, Michigan, and one site in Palm Coast, Florida. Our study investigated previously undescribed eukaryotic diversity in these habitats and further explored their bacterial communities. Mat samples and water parameters were collected from sulfur spring sites during the spring, summer, and fall of 2022. Cyanobacteria and diatoms were cultured from mat subsamples to create a culture‐based DNA reference library. Remaining mat samples were used for metabarcoding of the 16S and rbcL regions to explore bacterial and diatom diversity, respectively. Analyses of water chemistry, alpha diversity, and beta diversity articulated a range of high‐sulfur, low‐oxygen habitats, each with distinct microbial communities. Conductivity, pH, dissolved oxygen, temperature, sulfate, and chloride had significant influences on community composition but did not describe the differences between communities well. Chloride concentration had the strongest correlation with microbial community structure. Mantel tests revealed that biogeography contributed to differences between communities as well. Our results provide novel information on microbial mat composition and present evidence that both local conditions and biogeography influence these unique communities. [ABSTRACT FROM AUTHOR]

Cnidarians—the phylum including sea anemones, corals, jellyfish, and hydroids—are one of the oldest groups of predatory animals. Nearly all cnidarians are carnivores that use stinging cells called cnidocytes to ensnare and/or envenom their prey. However, there is considerable diversity in cnidocyte form and function. Tracing the evolutionary history of cnidocytes may therefore provide a proxy for early animal feeding strategies. In this study, we generated a time‐calibrated molecular clock of cnidarians and performed ancestral state reconstruction on 12 cnidocyte types to test the hypothesis that the original cnidocyte was involved in prey capture. We conclude that the first cnidarians had only the simplest and least specialized cnidocyte type (the isorhiza) which was just as likely to be used for adhesion and/or defense as the capture of prey. A rapid diversification of specialized cnidocytes occurred through the Ediacaran (~654–574 million years ago), with major subgroups developing unique sets of cnidocytes to match their distinct feeding styles. These results are robust to changes in the molecular clock model, and are consistent with growing evidence for an Ediacaran diversification of animals. Our work also provides insight into the evolution of this complex cell type, suggesting that convergence of forms is rare, with the mastigophore being an interesting counterexample. Highlights: Cnidarian stinging cells diversified through the Ediacaran, demonstrating that animal predation evolved before the Cambrian explosion. The mastigophore is rare case of a complex cell type evolving more than once. [ABSTRACT FROM AUTHOR]

The first occurrence of trilobites at ca. 520 Ma is an iconic feature of the Cambrian Explosion. Developing a robust evolutionary view on early Cambrian life is generally hindered by large uncertainties in the ages of fossil finds and their global stratigraphic correlation. We developed an astrochronological interpretation for the Tiout section in Morocco that features some of the oldest trilobite fossils. Our novel approach to incorporating individual astronomical cycle durations in an integrated radioisotopic and astrochronological Bayesian age-depth model results in an age estimate of 519.62 Ma (519.70-519.54 Ma 95% highest posterior distribution) for the first occurrence of trilobites in West Gondwana. This level of precise age estimation is exceptional for biological events in deep time and demonstrates the power of our novel approach. [ABSTRACT FROM AUTHOR]

Hyolitha represent one of the major constituents of the Cambrian Evolutionary Fauna, first appearing in the Terreneuvian and rapidly diversifying soon after. Recent work has both enriched the hyolith fossil record and expanded our understanding of their biology, but studies documenting the evolutionary trajectory of Cambrian hyoliths remain scarce. Here we present the first study of changes in morphological disparity in Cambrian hyoliths over time with the aim of characterizing the evolutionary trajectory of hyoliths throughout their primary period of diversification. Our results show that hyoliths occupied distinct regions of morphospace at different times during the Cambrian, with an expansion in morphospace occupation associated with the increase in hyolith diversity in the early Cambrian. Both the Sinsk Event and multiple abiotic factors led to a decline in hyolith diversity in the Miaolingian, and morphological disparity also contracts in association with this reduction in diversity. [ABSTRACT FROM AUTHOR]

The end‐Neoproterozoic transition marked a gradual but permanent shift between distinct configurations of Earth's biosphere. This interval witnessed the demise of the enigmatic Ediacaran Biota, ushering in the structured trophic webs and disparate animal body plans of Phanerozoic ecosystems. However, little consensus exists on the reality, drivers, and macroevolutionary implications of end‐Neoproterozoic extinctions. Here we evaluate potential drivers of late‐Neoproterozoic turnover by addressing recent findings on Ediacaran geochronology, the persistence of classical Ediacaran macrobionts into the Cambrian, and the existence of Ediacaran crown‐group eumetazoans. Despite renewed interest in the possibility of Phanerozoic‐style 'mass extinctions' in the latest Neoproterozoic, our synthesis of the available evidence does not support extinction models based on episodic geochemical triggers, nor does it validate simple ecological interpretations centred on direct competitive displacement. Instead, we argue that the protracted and indirect effects of early bilaterian innovations, including escalations in sediment engineering, predation, and the largely understudied impacts of reef‐building, may best account for the temporal structure and possible selectivity of late‐Neoproterozoic extinctions. We integrate these processes into a generalised model of early eumetazoan‐dominated ecologies, charting the disruption of spatial and temporal isotropy on the Ediacaran benthos as a consequence of diversifying macrofaunal interactions. Given the nature of resource distribution in Ediacaran ecologies, the continuities among Ediacaran and Cambrian faunas, and the convergent origins of ecologically disruptive innovations among bilaterians we suggest that the rise of Phanerozoic‐type biotas may have been unstoppable. [ABSTRACT FROM AUTHOR]

Premise of research. Polypodiaceae, the largest leptosporangiate fern family, is distributed mainly in the tropical and subtropical regions of India, China, New Zealand, and Malaysia. This family has a rich macrofossil record in the Cenozoic sediments of China, but no macrofossil of Polypodiaceae has been reported from the Cenozoic sediments of India to date. Here, we report for the first time the occurrence of fossil frond remains resembling morphologically those of the extant microsoroid wart fern genus Microsorum Link from the late Miocene Siwalik sediments exposed around Sarkaghat, Mandi district of Himachal Pradesh, Western Himalaya, India. Methodology. The present frond fossils were revealed by careful removal of the overlying matrix and studied under light compound, stereo zoom, and inverted fluorescence microscopes. They are identified based on their detailed morphological (macro and micro) features and through the comparison with other modern Polypodiaceae genera as well as with earlier reported polypodiceous fern fossil species. Pivotal results. The fossil frond specimens are described here as a new species, namely, Palaeosorum siwalikum Kundu, Hazra et Khan sp. nov. The new Siwalik vascular cryptogam species is characterized by leaf shape (simple frond with entire margin), venation pattern (brochidodromous nature of secondary veins, tertiary and quaternary veins reticulate, anastomosing and forming a row of irregular or quadrangular-shaped areoles between two lateral secondary veins), and presence of free included veinlets (unbranched or forked, ending with club-shaped hydathodes). Conclusions. These new fossil materials confirm the existence of a Microsorum -like plant in the Siwalik Miocene forests of Himachal Pradesh. We review in detail the fossil record and highlight the phytogeographic history of Polypodiaceae. In addition, we also suggest probable migratory routes for this fern family. [ABSTRACT FROM AUTHOR]

A study of previously collected fossils and of new data on Cambrian mollusks from the Bayangol Formation of Western Mongolia (Zavkhan structural-facies zone) revealed a significant similarity in the taxonomic composition of the mollusk assemblages of Western Mongolia and Southern France (Heraultia Limestone, Marcou Formation, Montagne Noire). In addition to the previously reported four common species (Latouchella korobkovi (Vostokova, 1962), Protoconus orolgainicus (Zhegallo, 1996), Purella tenuis Zhegallo, 1996, and Watsonella crosbyi Grabau, 1900), we have identified ten more common species for these regions including Auricullina auriculata (Vassiljeva, 1990); Bemella jacutica (Missarzhevsky, 1966); "Calbyella" multicostata Missarzhevsky, 1995; Cambroscutum concameratum Kerber, 1988; Helcionella sp.; Merismoconcha tommotica (Zhegallo, 1996); Obtusoconus amplus (Zhegallo, 1982); Prosinuites tripartitus Kerber, 1988; Purella layracensis (Kerber, 1988); and Securiconus sp. We have to reconsider the existing reconstruction of faunal relations of paleobasins on the western framework of Gondwana in terms of substantiating a close faunal exchange with the Zavkhan terrane, which was during the Early Cambrian a part of the chain of microcontinents located at low latitudes between the Siberian Platform in the west and Gondwana in the east. [ABSTRACT FROM AUTHOR]

The Cambrian and Ordovician radiations marked the origins of all major echinoderm clades and established their Phanerozoic ecological blueprint. Recent claims of modest innovation of early echinoderms and other animals suggest constraints on novelty during the origins of phyla. Here, we document the life‐habit richness, body size, tiering, habitat usage, mobility, diet and foraging habits of 366 Cambrian–Ordovician echinoderm genera across a time‐scaled phylogeny to identify the timing and impact of novelty. Most early echinoderms were sedentary, filter‐feeding microbivores, and their body sizes, diets and modes of locomotion were largely unchanged through time, despite major volatility in taxonomic composition. Cambrian echinoderms lived close to the seafloor, with stylophorans first evolving semi‐infaunality. Many Ordovician echinoderms lived farther from the seafloor, with more complex filter‐feeding organs and tiering structure, often using other organisms as substrates. Mobile carnivores and mass‐feeders emerge then, too, across diverse asterozoans and echinozoans. Most of these novelties coincide with the origins of individual clades during the early and late Cambrian (Terreneuvian/Series 2 and Furongian), and 10–20 million years pass before most become ecologically important. Life‐habit evolution within most taxa involved new variations in these traits, with crinoids and asterozoans better able to shift strategies. The Ordovician radiation records more new variability in pre‐existing Cambrian life habits rather than radical re‐invention, with important novelties (like mobile carnivory and mass‐feeding, increased height off the seafloor, and biotic substrates) becoming ecologically more impactful. Taxa with these strategies were those best able to capitalize on the newly heterogeneous Ordovician world. [ABSTRACT FROM AUTHOR]

The tectonic affinity of the Korean Peninsula in reference to the Permo-Triassic collision of the Sino-Korean Craton (SKC) and the South China Craton (SCC) has been in the center of debates over the last three decades. Since the Imjingang Belt that runs through the middle part of the Korean Peninsula is thought to represent the major tectonic boundary, most part of North Korea, including the "Pyeongnam Basin" in the southern part, has been regarded as part of the SKC. However, differences in stratigraphy and the fossil occurrence have been recognized by local geologists between the southern part of "the Pyeongnam Basin" (SPB) and the northern part of the "Pyeongnam Basin" (NPB), and which have hardly been considered for the paleogeographical affinity of the regions so far. Here we provide a comprehensive review on 1,072 fossil taxa from the Neoproterozoic to middle Paleozoic sedimentary successions of North Korea, and utilize the data for determining tectonic affinity of the regions. Especailly, Cambrian trilobite genera from the SPB and NPB have been quantitatively compared with those of North China (the SKC) and the SCC, using similarity indices, the non-metric multidimensional scaling (NMDS), and PerMANOVA test. The results have revealed that the SPB is tied to the SCC, not to North China (the SKC), whereas the NPB is closely related to North China. The SCC affinity of the SPB is corroborated by stratigraphical features, such as the presence of the Precambrian–Cambrian boundary and the middle Paleozoic strata, which are largely absent in the SKC. Our results demonstrate that the SPB region likely originated from to the SCC, and thus further suggest that the collisional boundary of supracrustal rocks between the SKC and the SCC in the Korean Peninsula corresponds to the boundary of the NPB and the SPB. Accordingly, the extent of the newly-defined Pyeongnam Basin is restricted to the traditional NPB region. The SPB region is included in the extent of the newly-proposed Hwanghae District, which is bounded to the east with the Imjingang Belt by the Ryesonggang Fault. The South China Craton-originated rocks of the Hwanghae District and the Imjingang Belt are collectively termed the South China-affinity terrane (SAT). [ABSTRACT FROM AUTHOR]

Southeastern Newfoundland, Canada, is home to the oldest Ediacaran fossils in the Avalonian Assemblage mostly being preserved beneath tuffites in association with microbial matgrounds. A unique fossiliferous surface at Upper Island Cove, known as the Allison Surface, exhibits three-dimensional preservation of Ediacaran fronds without an associated tuffite or microbial matground. Previous models have invoked entrainment of fronds within turbidity currents, or by their felling into erosive scours. Our work demonstrates that the fossils were preserved within beds before being partially exhumed and cast by a subsequent sandy turbidite. Many of the structures previously identified as rangeomorph stems are longitudinal erosional features within obstacle sours. Additional observations of stemmed/erect organisms coinciding with reclined taxa suggest cross-cutting/palimpsesting of frondose taxa with deeply emplaced holdfasts. Many of the fossil organisms are found within the top of a Td unit, with early pyritization probably aiding in their three-dimensional preservation. Most fronds are incomplete and oblique to the axis of the surrounding scours, indicating they were partly exhumed after burial. The scours likely formed in the lee of erect stemmed rangeomorph and arboreomorph taxa, which are commonly preserved as holdfasts on the surface, and occasionally crosscut buried fronds. The crosscutting of frondose taxa by holdfasts and the presence of pyritic tubes in the overlying sedimentary units suggests the preservation of three separate communities: 1) the initial Td entombed mainly reclined organisms; 2) a pre-turbidity current community of erect taxa with bulbous holdfasts that were the loci of obstacle scours; and 3) a later community of erect organisms preserved as holdfasts/stems. [ABSTRACT FROM AUTHOR]

Extensive phosphorite deposition is observed in the Neoproterozoic after a prolonged hiatus during most of the Mesoproterozoic era. This event is thought to represent an important record of major palaeoenvironmental, palaeoceanographic and biotic changes that shaped Neoproterozoic ecosystems, suggesting close relationships between phosphogenesis and the preservation of key Ediacaran biotas. However, high‐grade Ediacaran phosphorite deposits are relatively uncommon, diminishing the opportunity to test current phosphate mineralization–deposition models and their implications for Neoproterozoic research. In this scenario, widespread Ediacaran phosphorite–dolomite–shale successions of the Bocaina Formation (Corumbá Group – Central Brazil) are poorly explored in international literature. Nevertheless, recent advances in phosphate exploration gave access to continuous drill core sections and freshly opened mine pits, revealing an unprecedented record of complex phosphatic successions featuring the occurrence of Ediacaran microfossils assigned to the Doushantuo–Pertatataka assemblages. This work seeks to constrain main lithofacies, sequence stratigraphy and depositional settings from these phosphatic successions in order to analyse the sedimentary evolution of the unit under the current Neoproterozoic phosphorite research framework. These results indicate that the Bocaina Formation records secular sustained phosphate deposition. These deposits are related to unprecedented, microbialite reef rim phosphorites deposited during a lower accretionary rimmed platform stage, followed by the deposition of Doushantuo‐like, whole platform phosphorites associated with a later, drowned platform stage, therefore, reinforcing the evidence for the operation of strong allogeneic controls on phosphate mineralization–concentration. In addition, this study concludes that fossiliferous Ediacaran phosphatic deposits such as the Bocaina Formation are important to understanding Neoproterozoic phosphogenic events, because they may record the transition from a Precambrian to Phanerozoic‐like phosphogenesis associated with the instauration of the Ediacaran–Cambrian phosphatic taphonomic window. This evidence hints that the growing dataset from the Bocaina Formation may bring new, exciting perspectives for Neoproterozoic research as a whole. [ABSTRACT FROM AUTHOR]

The phosphorus content in the dry matter of modern-day Cnidarians (Hydrozoa, Scyphozoa and Anthozoa) collected in the different parts of the world's oceans ranges from 0.14 to 1.3% wt. Nektonic Cnidarians can form major aggregations in marine basins and should therefore be regarded as an important component of phosphorus flux into sediment. Seventy-five per cent of the Ediacaran fossils were interpreted as the moulds of soft-bodied organisms resembling modern-day Cnidaria. Therefore, ancient Cnidarians in the Ediacaran epeiric basins could be a source of phosphorus during the deposition of the earliest sedimentary phosphorites. [ABSTRACT FROM AUTHOR]

The Precambrian‐Cambrian (Pc‐C) boundary marks significant biological, atmospheric, and oceanic changes. These changes include extinction of the Ediacaran fauna, initiation of complex lifeforms, and oxygenation of the atmosphere and oceans. In this contribution, elemental and Mo‐S isotopic compositions of organic‐rich shales overlying the Pc‐C boundary from the Tal Formation, Lesser Himalaya, have been investigated. These datasets are used to reconstruct past oceanic redox state and sulfate concentrations. The principal component analysis of the elemental dataset identifies six major factors, with factors associated with organic matter and sulfide phases accounting for about half of the total variance. Iron speciation and Mo/U data suggest that the shales were deposited in anoxic and ferruginous deep water conditions. The δ98Mo data (1.5 ± 0.2‰) and their mass balance calculations indicate that the areal extent of sulfidic waters and pyrite burial rates were about 2–4 times higher during the Pc‐C transition than in the modern ocean. The pyrite‐δ34S values (3.6–8.3‰) for the Tal shales are isotopically heavier compared to modern‐day sedimentary pyrites (∼−21‰). Calculations involving earlier‐reported δ34S values for early Cambrian seawater and our measured pyrite‐δ34S data estimate the seawater sulfate concentration (8 ± 3 mM) during their deposition. This sulfate value for the Tal basin is higher than that reported for the late Neoproterozoic ocean (<5 mM), attributable to increasing oxygen availability and continental supply during this time. The observed basinal conditions and high terrestrial input may have influenced metazoan diversification. Key Points: Chemical and Mo‐S isotopic study of black shales overlying the Pc‐C boundary from the Tal Formation (Lesser Himalaya) was carried outTrace element, Fe‐speciation and Mo isotopic data suggest a stratified basin with anoxic and ferruginous bottom water conditionsHigher seawater sulfate (∼8 mM) during the Pc‐C transition (than Proterozoic) linked to atmospheric oxygenation and enhanced riverine input [ABSTRACT FROM AUTHOR]

Matamata turtles (Chelus Duméril, 1806) are composed of two extant species, Chelus fimbriata Schneider, 1783 and Chelus orinocensis Vargas-Ramírez, Caballero, Morales-Betancourt, Lasso, Amaya, Martínez, Silva-Viana, Vogt, Farias, Hrbek, Campbell & Fritz, 2020, inhabitants of the main freshwater drainages of northern South America. The systematics and palaeobiogeography of Chelus is still unresolved. Here, we describe several new fossil specimens from the Late Miocene of Urumaco (Venezuela) and Tatacoa (Colombia). The fossils are mostly complete, articulated shells that allow reestablishing validity of two extinct taxa, Chelus colombiana Wood, 1976 and Chelus lewisi Wood, 1976. One of the specimens of C. lewisi from Urumaco represents the first record within the genus for which autopodial bones (a left manus) and additional limb bones are preserved together with ashell, demonstrating evolutionary conservatism in limb anatomy for the genus. The specimen comes from the Socorro Formation, representing the earliest so far known record of Chelus for the Urumaco sequence. Additionally, one specimen from Tatacoa is the first fossil for which cervical and pectoral girdle elements are preserved. Phylogenetic analysis supports the existence of two separate clades inside of Chelus, one formed by the extinct species and the other by the extant ones. [ABSTRACT FROM AUTHOR]

In this study, we report well-preserved fossil remains of Nimbia from the Ediacaran Sonia Sandstone of Jodhpur Group, Marwar Supergroup in the Sursagar area of Jodhpur district, Rajasthan, western India. Here, two species of Nimbia, namely Nimbia occlusa and Nimbia dniesteri, have been recorded on medium- to fine-grained sandstone bedding surfaces. The N. occlusa forms are circular to ovate and elliptical imprints with a smooth and flat central part and enclosed by a single thick, annular marginal rim, whereas the N. dniesteri remains are circular to sub-circular discoid impressions with a trapezoidal structure. Here, the recorded N. occlusa is common compared to the N. dniesteri fossil forms in the Ediacaran Sonia Sandstone. These Nimbia fossil forms are found in the Sonia Sandstone in terrestrial to marginal marine habitats with moderate hydrodynamic forces. [ABSTRACT FROM AUTHOR]

The last common ancestor of animals is thought to have been small and soft-bodied and therefore would have required special conditions for its preservation. Limited availability of these conditions in the Neoproterozoic could explain the discrepancy between molecular clock predictions for the timing of animal origins and the fossil record of animals. We assess the availability of these conditions, particularly those of Burgess Shale-type, which are known to preserve animals with tissues of varied composition. Burgess Shale-type conditions are rarely associated with Neoproterozoic fossil biotas, but in the few assemblages with these conditions, dated to 789 million years ago or older, no animals have been identified, suggesting they had not evolved by this time. This provides a soft maximum age constraint on crown group animals of 789 million years ago. Estimates for animal antiquity exhibit a significant disconnect between those from molecular clocks, which indicate crown animals evolved ∼800 million years ago (Ma), and those from the fossil record, which extends only ∼574 Ma. Taphonomy is often held culpable: early animals were too small/soft/fragile to fossilise, or the circumstances that preserve them were uncommon in the early Neoproterozoic. We assess this idea by comparing Neoproterozoic fossilisation processes with those of the Cambrian and its abundant animal fossils. Cambrian Burgess Shale-type (BST) preservation captures animals in mudstones showing a narrow range of mineralogies; yet, fossiliferous Neoproterozoic mudstones rarely share the same mineralogy. Animal fossils are absent where BST preservation occurs in deposits ≥789 Ma, suggesting a soft maximum constraint on animal antiquity. [ABSTRACT FROM AUTHOR]

Multicellular algae are the core topic for understanding the early life evolution on Earth. The timing of origin and cellular differentiation of multicellular algae, however, remains poorly constrained. The Palaeoproterozoic to early Mesoproterozoic is a critical period during which multicellular algae began to occur and evolve in marine environments. This paper reports well‐preserved multicellular fossils from shales of the Chuanlinggou Formation (c. 1.64 Ga) in North China, with emphasis on their holdfast and putative cellular structures. These macroalgal fossils are reasonably diversified and include Chuaria circularis, Tawuia sinensis, Tawuia robusta, Glossophyton ovalis, Glossophyton sp., Tuanshanzia sp. and Changchengia sp.; mainly preserved as carbonaceous compressions, with a few sideritized forms. Field emission scanning electron microscope (FESEM) observation revealed multicellular structures in Chuaria, confirming its biological attributes of a multicellular eukaryote and providing direct evidence that multicellular algae had already originated by the terminal Palaeoproterozoic, earlier than previously speculated. Tuanshanzia sp. and Changchengia sp. developed with a bare rhizome holdfast, suggesting that they had a benthic sessile lifestyle in their late Palaeoproterozoic oceanic habitat. [ABSTRACT FROM AUTHOR]

Extant species of Liquidambar L. exhibit a disjunct distribution between western and eastern Asia and eastern North America to Central America, with the highest species diversity being in China. In this study, two new species of Liquidambar are described from the Eocene of Hainan Island, South China: L. hainanensis on basis of the leaf fossils, and L. ovoidea based on compressions of infructescences. The co‐occurrences of L. hainanensis leaves, associated infructescences of L. ovoidea and dispersed pantoporate pollen grains have the combination of morphological features peculiar to the genera Liquidambar and former Semiliquidambar and Altingia. This is considered further palaeobotanical justification for the placement of these three genera into a single genus, Liquidambar, proposed earlier based on molecular markers. Our data provide evidence for the occurrence of an ancestral polymorphic group of Liquidambar species (L. maomingensis with associated capitate infructescences, L. bella, L. hainanensis and L. ovoidea) during the Eocene in South China, and corroborate the view that South China could have been a centre of Liquidambar speciation during the Eocene. The morphological similarity of L. hainanensis leaves to those of the extant species L. orientalis from Western Asia and the North American L. styraciflua may support the importance of both the North Atlantic Land Bridge and the Bering Land Bridge for the dispersal of Liquidambar. Analysis of fossil species of Liquidambar from eastern Asia also contributes to further understanding of patterns in the taxonomic diversity and evolutionary history of this genus. [ABSTRACT FROM AUTHOR]

Fossil material assigned to Nenoxites from the late Ediacaran Khatyspyt Formation of Arctic Siberia (550–544 Ma) has been presented as evidence for bioturbation prior to the basal Cambrian boundary. However, that ichnological interpretation has been challenged, and descriptions of similar material from other global localities support a body fossil origin. Here we combine x‐ray computed tomography, scanning electron microscopy and petrographic methods to evaluate the body or trace fossil nature of Nenoxites from the Khatyspyt Formation. The fossilized structures consist of densely packed chains of three‐dimensionally preserved silicic, bowl‐shaped elements surrounded by distinct sedimentary halos, in a dolomitized matrix. Individual bowl‐shaped elements can exhibit diffuse mineralogical boundaries and bridging connections between elements, both considered here to result from silicification and dolomitization during diagenesis. This new morphological and petrological evidence, in conjunction with recent studies of the late Ediacaran tubular taxa Ordinilunulatus and Shaanxilithes from China, suggest that the Khatyspyt specimens most probably reflect a coquina deposit of Shaanxilithes‐like body fossils. Our data support the possibility of Shaanxilithes‐like organisms representing total group eumetazoans. [ABSTRACT FROM AUTHOR]

Currently, studies of ancient faunal community networks have been based mostly on uniformitarian and functional morphological evidence. As an important source of data, taphonomic evidence offers the opportunity to provide a broader scope for understanding palaeoecology. However, palaeoecological research methods based on taphonomic evidence are relatively rare, especially for body fossils in lacustrine sediments. Such fossil communities are not only affected by complex transportation and selective destruction in the sedimentation process, they also are strongly affected by time averaging. Historically, it has been believed that it is difficult to study lacustrine entombed fauna by a small-scale quadrat survey. Herein, we developed a software, the TaphonomeAnalyst, to study the associational network of lacustrine entombed fauna, or taphocoenosis. TaphonomeAnalyst allows researchers to easily perform exploratory analyses on common abundance profiles from taphocoenosis data. The dataset for these investigations resulted from fieldwork of the latest Middle Jurassic Jiulongshan Formation near Daohugou Village, in Ningcheng County of Inner Mongolia, China, spotlighting the core assemblage of the Yanliao Fauna. Our data included 27,000 fossil specimens of animals from this deposit, the Yanliao Fauna, whose analyses reveal sedimentary environments, taphonomic conditions, and co-occurrence networks of this highly studied assemblage, providing empirically robust and statistically significant evidence for multiple Yanliao habitats. A new method and its companion software to study the associational network of lacustrine entombed fauna, or taphocoenosis. The application allows researchers to easily perform exploratory analyses on common abundance profiles from taphocoenosis data. [ABSTRACT FROM AUTHOR]