A diverse shallow-water shelly fauna, dominated by brachiopods, gastropods, corals, and stromatoporoids, was recovered from the carbonate-rich Koumenzi Formation (Katian, Upper Ordovician) in the Qilian Mountains, Northwest China. From this assemblage, 100 bellerophontoid gastropod specimens were systematically identified as four genera (Sinuites?, Qilianodiscus n. gen., Pterotheca, and Cymbularia) and two new species (Qilianodiscus qilianensis n. sp. and Cymbularia sinensis n. sp.). Among these, the new genus Qilianodiscus is established based on its distinctive lenticular, thick-shelled morphology with a nearly closed umbilicus and reflected aperture. The wellpreserved shells, found together with abundant brachiopods and bivalves retaining conjoined valves, indicate in-situ preservation, providing valuable information for paleoecological reconstruction. Functional morphology analysis indicates that features such as aperture thickening and lateral expansion served as adaptations to soft substrates and for maintaining balance in high-energy settings. The diverse filter-feeding community and carbonate microfacies indicate a nutrient-rich, shallow marine environment with abundant green algae. Furthermore, the study establishes a spatial and ecological association between these shell-rich deposits and adjacent reef buildups. These reef structures acted as physical buffers that reduced disturbance on the benthic habitat. (c) 2026 Nanjing Institute of Geology and Palaeontology. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

The North Qilian Mountains region is an important component of the Proto-Tethys Archipelagic Palaeocean. The Koumenzi Formation (Katian, Upper Ordovician) in the region yields a significant number of Ordovician fossils, of which cephalopods have rarely been systematically studied and recorded. Herein, a moderately preserved cephalopod collection from the Koumenzi Formation is presented from the North Qilian Mountains, Qilian Orogenic Belt. This fossil assemblage, obtained from the section near the upper reaches of the Tianbao River, Qilian County, Qinghai Province, consists of Anaspyroceras sp., Geisonocerina? sp., Paradnatoceras nyalamense, as well as some unnamed oncoceratoid and orthoceratoid cephalopods. Furthermore, quantitative palaeoecological analyses based on global occurrences, uncover notable provincialism of Katian cephalopods. Two cephalopod provinces related to palaeolatitude are recognised by cluster analysis and weighted network analysis. Global oceanic currents might have been responsible for the pattern of the (c) 2025 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Phosphate deposits of both sedimentary and igneous origins are the most important sources of phosphorus in the world. Neoarchean metamorphic series-hosted apatite-magnetite deposits in the northern North China Craton (NCC) are important sources of P and Fe. However, the genesis of some deposits remains controversial, as they are proposed to have formed through sedimentary-metamorphic processes in the phosphorus-deficient Neoarchean environment. The Wulanwusu P-Fe deposit in the Jianping area is a typical example, with the P-Fe mineralization typically composed of plagioclase, amphibole, biotite, apatite and Fe-Ti oxides. This study aims to constrain the geological controls on P-Fe mineralization through petrographic, geochronological, and geochemical analyses of P-Fe ores. Zircon U-Pb geochronology yielded a weighted crystallization age at 1730 +/- 6 Ma, precisely constraining the timing of mineralization to the late Paleoproterozoic. Petrographic observations, whole-rock and apatite geochemistry collectively indicate that the mineralization is associated with a mafic magmatic event, supporting its classification as a late Paleoproterozoic igneous P-Fe deposit. Our results clearly rule out a previously suggested link between P-Fe mineralization and metamorphosed Neoarchean volcanosedimentary rocks. The Nd-Hf isotopic compositions suggest that the parental magma was derived from an enriched subcontinental lithospheric mantle source. Combined with geochronological and geochemical evidence, these results indicate that the formation of the Wulanwusu P-Fe deposit is linked to the late Paleoproterozoic AMCG suite magmatism in the northern NCC and occurred in a post-collisional extensional stage following the convergence of the eastern and western blocks of the NCC.

Being a quite small part of minute plants, cryptospores provide us with a very large window to look into the early greenery of the Earth. Although the last common ancestor of land plants may have evolved in the Proterozoic, plants with complex multicellular sporophytes ushered substantial diversification only from the Devonian. During the intervening time interval, cryptospores left key fossil record about the early land plant evolution. Here, we present a comprehensive overview of the cryptospore fossil record from the perspectives of morphology, taxonomy, biostratigraphy, biodiversity, paleogeography and biological affinity. Two different concepts of cryptospores, both sensu lato and sensu stricto, have been developed, especially in relation to whether this group involves the Cambrian sporomorphs in the algal-plant evolutionary transition. Based on over 200 studies spanning from the late early Cambrian through Middle Devonian (ca. 515 to 390 Ma), we evaluate the temporal diversity and spatial differentiation of cryptospores s.l. by quantitative means such as Chao2 estimator, non-metric multidimensional scaling and network analysis. The results underscore that 1) according to available fossil data, the Late Ordovician-early Silurian witnessed the initial expansion of early land plants in species diversity and distribution, with an increased potential for geographical differentiation; 2) as trilete spores emerged, geographical differentiation became more distinct among spore assemblages during the middle-late Silurian, but without further diversification of cryptospores; 3) palynofloras may still host diverse cryptospores in the Early Devonian, just before the demise of these spores; and 4) higher spatial, temporal and taxonomic resolution is required to fully decipher the spore-based early land plant evolution in the future. A newly compiled set of stratigraphic ranges of all cryptospore species shows necessity and prospect of recalibrating spore biozonation schemes with an increasing accumulation of fossil data. The nature of these microfossils recovers an evolving path from ancestral streptophyte algae to early embryophytes (eophytes), although the complete phylogenetic relationships of cryptospore-producing organisms remain to be elucidated. It is expecting to disclose some long-standing mysteries of plant terrestrialization with the research opportunities offered by cryptospores and the application of interdisciplinary approaches.

Paleoproterozoic metamorphic rock series are widely distributed and hosts several iron deposits. The Heiyuting iron (Fe) deposit is hosted by typical Paleoproterozoic leptite of the Li'eryu Formation and represents a key example for constraining the mineralization process of Paleoproterozoic iron deposits within the Liaohe Group. This type of deposit has great exploration potential, but the precise timing of iron mineralization, the sources of ore-forming materials, and iron mineralization processes remain unclear. We conducted zircon and monazite U-Pb geochronology together with monazite electron probe microanalysis (EPMA) to constrain iron mineralization. Zircon cores from the migmatitic granite yield an age of 2174 +/- 23 Ma, representing protolith formation, whereas the rims yield 1892 +/- 14 Ma, consistent with similar to 1900 Ma granulite-facies metamorphism. Monazite grains associated with magnetite yielded an age of 1848 +/- 5 Ma, constraining Fe mineralization and coinciding with regional partial melting (1870-1840 Ma). Monazites observed under back-scattered electron (BSE) imaging show embayed structures and concentric coronas composed of apatite, allanite, and epidote. Based on the major-, trace-, and REE-element compositions of monazite, a metamorphic-hydrothermal origin is suggested. We propose that the apatite-allanite-epidote coronas developed on early-formed monazite through disequilibrium reactions with F-Ca-Fe-Si-Al-rich fluids during the retrograde metamorphic stage. The Li'eryu Formation and the 2.2-2.1 Ga magmatism provided the primary sources of iron. The iron was subsequently concentrated by hydrothermal activity during late metamorphism-anatexis at similar to 1850 Ma. Our results refine the age, source, and mechanisms of iron mineralization in the Heiyuting Fe deposit, provide geochronological and geochemical constraints for similar deposits, and highlight the role of regional metamorphism-anatexis in polymetallic enrichment.

Graphoglyptids such as Paleodictyon and Protopaleodictyon are typical members of the Nereites ichnofacies, but occasionally they also occur in shallow waters beyond the deep sea. Here, we report Paleodictyon arvense, P. goetzingeri and Protopaleodictyon isp., alongside other trace fossils of the proximal Cruziana ichnofacies from the middle-upper Aeronian, Yangtze Platform, South China. The trace fossils were recognized within intervals deposited in the transitional zone between the lower shoreface and the inner shelf settings, as well as the delta front environment. Compiling examples of shallow-water Paleodictyon and Protopaleodictyon suggest that these trace fossils occurred in a variety of shallow-marine settings, including nearshore, shelf, and slope areas, as well as fluvial and lacustrine environments. Graphoglyptids originated in shallow shelves before migrating into deeper facies during the Early Ordovician. The return of Paleodictyon and Protopaleodictyon in shallow-marine facies after that time generally reflects high sedimentation rates, low bioturbation intensity, low benthic-food delivery and occasional event deposition in relatively quiet local circumstances. The onset of prevailing suboxic, stressed conditions during the Aeronian may have presented a colonizing window for the tracemakers of Paleodictyon and Protopaleodictyon to expand their life habitats in shallow- and marginal-marine settings, prior to higher stages of biotic recovery during the early Silurian.

Fluvial-delta plain complex links land, fresh water, and marine habitats and acts as a springboard during terrestrialization of both plants and animals. Its geological records or related paleoecology study, during mid to late Paleozoic, however, are scarce. In this study, we reconstruct the paleoenvironmental and paleoecological framework of a Middle Devonian (c. 387 Ma) fluvial-delta plain complex from Wuding, eastern Yunnan, South China for the first time, using a combined approach of sedimentology, geochemistry, and palaeontology. Eight lithofacies of fluvial-delta plain are recognized from the Haikou Formation. The lower part of the Haikou Formation deposited in a meandering fluvial environment. While the middle-upper part of the Haikou Formation is interpreted as a brackish-fresh water setting (i.e., delta plain-swamp) based on facies analysis, stable isotope composition (delta 18O, delta 13C) of biogenic (ostracods) and authigenic carbonates, as well as paleosalinity proxies (Sr/ Ba). A synthetic biota with a variety of fossil organisms, including ostracods (29 species belonging to 7 super-families), charophytes (1 species), chondrichthyans and antiarch fishes (at least 2 taxa), gastropods (1 taxa), bivalves, and spores (20 species belonging to 19 genera) have been recognized and identified in the delta plain-swamp facies. Ostracods are categorized into three distinct assemblages. Assemblage 1 (Leperditicope-Palaeocope assemblage) and Assemblage 3 (Paraparchitoidean assemblage) displaying high diversity and abundance, and characterize a brackish lower delta plain and a delta plain-swamp environment, respectively. Whilst the Assemblage 2 (Leperditioidean assemblage) has relatively low diversity and inhabited in fresh water, probably an upper delta plain setting. Leperdiditioideans are pioneers colonized fluvial-delta plain setting and might be the earliest fresh water ostracods. Additionally, a special fresh water species of Cypridoidea, Carbonita sp., which has never been reported prior to the Carboniferous Period, is discovered in the Haikou Formation. Abundant rhizomes of vascular land plants, as well as vertically arranged traces fossils (i.e., Scoyenia beerboweri) are observed from the flood plain facies, representing development of belowground soil ecosystem. The biota, especially those of the ostracods and charophytes, comprise a complex ecosystem spanning the marginal marine to terrestrial settings allowing a well-structured reconstruction of the eco-pyramid of brackish-fresh water ecosystem during the Middle Devonian. The results shed light on the co-evolution of the environment and organisms in the Devonian non-marine system.

The first set of Silurian marine red beds(FSRB) in South China exhibits distinct identification markers and spatial distribution. The origin of these red beds is intricately linked to the regional and global tectonic, paleo-oceanic, and paleoclimatic evolutionary processes. However, the scarcity of key fossils and the endemic characteristics of discovered taxa have posed challenges to intercontinental correlation and have led to divergent opinions regarding their age assignment, thereby impeding further in-depth research. Drawing upon fossil evidence from graptolites, conodonts, chitinozoans, brachiopods, and trilobites,this study comprehensively analyzes the age of the FSRB formed under varying paleogeographic conditions in South China. The findings reveal that the FSRB generally situated within the middle Aeronian to lower Telychian, Llandovery(ca. 436–439 Ma),corresponding to the graptolite Lituigraptus convolutus Biozone(LM7), the Stimuloraptus sedgwickii Biozone(LM8), the Spirograptus guerichi Biozone(LM9), and the S. turriculatus Biozone(LM10). A notable diachronous pattern is observed for the base of the FSRB, becoming younger from east to west and from south to north. Specifically, the FSRB first emerged along the south margin of the Dabie Oldland during the middle Aeronian. Subsequently, they appeared progressively in the MiddleLower Yangtze/Jiangnan district during late Aeronian and in the Upper Yangtze region near the Aeronian/Telychian boundary.Finally, they occurred around the Chuanzhong Oldland during early Telychian. While the top boundary of the FSRB varies at different localities, it consistently lies below the middle Telychian strata containing the Xiushan Fauna. In the context of global oceanic oxidation in tropic seas, the dynamic spatiotemporal distribution of the FSRB in South China reflects a gradual retreat of anoxic and semi-anoxic waters from shallow seas towards the open ocean, replaced by oxygenated waters over a period of approximately 3 million years across the Aeronian/Telychian boundary. This process is closely associated with the continuous and rapid uplift of the seabed triggered by the northwestward expansion of the Cathaysian Oldland during the Kwangsian Orogeny.

A shallow-water trilobite fauna, with low diversity (seven species of six genera), from the Koumenzi Formation (Katian) in the Qilian area, northeastern Qinghai Province, Northwest China, is recognised as the Pliomerina Association. Of these, Dulanaspis and Amphilichas are reported for the first time in the North Qilian Mountains. The shallow-water Pliomerina and relatively deep-water BirmanitesSinocybele associations were found to occur in the Qilian and Menyuan areas, respectively, during the Katian. They exhibit a distinctive ecological differentiation with water depth from inner shelf to outer shelf environments. The Pliomerina Association of the Qilian area clearly belongs to the Pliomerina and/or Sinocybele Province of the Proto-Tethys Archipelagic Ocean. Faunal evidence indicates that the palaeogeographical position of the North Qilian Mountains area was situated closer to the Kazakh terranes during the Katian, particularly to the Chu-Ili and Chingiz-Tarbagatai terranes. (c) 2025 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

The only known fossil of Cystodium (Cystodiaceae) is C. sorbifolioides from mid-Cretaceous Myanmar amber. Here we describe a new fossil species of Cystodium, C. parasorbifolium, also from amber collected in Myanmar. This new species belongs to Cystodium based on pinnate fertile lamina segments, terminal sori protected by a reflexed lobe of the lamina (outer or false indusium), free veins, vertical annuli interrupted at the stalk, trilete spores, and striate perines. It differs from C. sorbifolioides by reflexed ovate-conical indusia and spores with clear striate perines. This new fossil species suggests that Cystodium was more diverse in the forests of Myanmar during the Cretaceous.

The upper Silurian of South China records the first, and perhaps the only occurrence of widespread (spanning over 1400 km), thick to very thick bedded Thalassinoides facies (TVTFs) after the Late Ordovician mass extinction. However, the palaeobiological, palaeoecological features and potential significance of these facies are yet to be demonstrated. A case study at northwestern Hunan Province, middle to upper Yangtze Block, reports the occurrence of TVTFs in a storm dominated open marine succession of the upper Silurian Xiaoxi Formation, which can be further assigned to lower offshore, upper offshore, offshore transition to distal lower shoreface, and proximal lower to middle shoreface settings. The regular changes of bioturbation intensity and maximum penetrating depth from various settings suggest that local energy levels, especially frequency of storms could have controlled the development of Thalassinoides, while their burrow sizes were generally confined by population densities. The Thalassinoides facies could have been constructed by unknown crustaceans, which generally conducted a deposit-feeding strategy. The return of widespread TVTFs in the tropical oceans of South China during the late Silurian could reflect a restored primary productivity, an elevated oxygen level, and a final recovery of benthic ecosystem to pre-extinction level after the Late Ordovician mass extinction. TVTFs could have remarkably shaped the late Silurian benthic environment in view of their high abundance, large burrow sizes, nature of deep tiered burrow systems and a deposit-feeding strategy.

Fleshy fruits are classified as ethylene dependent or ethylene independent according to the ethylene production rate at the onset of ripening. However, the mechanism regulating ethylene production in fruits is unclear. Pears (Pyrus spp.) contain both types of fruits. Analyses of 5 Pyrus genomes and 109 resequenced pear accessions revealed an important chromosomal locus closely associated with ethylene-producing phenotype. This locus was closely linked to a novel long noncoding RNA (lncRNA). Interestingly, the expression of this lncRNA showed an opposite pattern to ethylene production. Fruits overexpressing this lncRNA displayed extremely low ethylene production and a late ripening phenotype, which was observed for both tomatoes and pears. Therefore, this lncRNA was termed Ethylene Inhibiting Factor (EIF). Variable deletions of 3.8 kb and 1.1 kb regions altered EIF expression and enabled the categorization of pears into six genotypes. The huge number of transposable elements (TEs) were observed and they probably drove fragment rearrangement, generating the EIF, which repressed the ethylene production, resulting in ethylene-independent pear fruit. These findings provide new insights into the molecular basis of ethylene-producing phenotype in Maloideae fruits.

A large, three-dimensional burrow system with a maximum vertical extension of 34 cm and a maximum covering area of 40 × 50 cm is reported from the Lower Devonian Pingyipu Formation of the northwestern Yangtze platform, South China. The burrow system, erected as Guangyuanichnus majianus n. igen. n. isp., is composed of two elements, i.e., a basal part that consists of several arcuate burrows, and an upper part emerging from the distal part of each arcuate burrow, which consists of radial, horizontal to subhorizontal spreite bodies in multiple levels in the substrate. The morphologic and taphonomic features of the basal and upper parts, the comparison of ecological and behavioral characters as well as the resulting burrows among various groups suggest that the burrow system was probably constructed by an unknown group of deposit-feeding bivalves. These animals burrowed to a medium to deep tier in the shoreface setting, where they constructed the basal arcuate burrows, and extended the agile siphon far out of the burrow to systematically exploit surficial materials for consumption. The behavior of the tracemaker and resulting trace fossils closely resemble those of modern and ancient tellinacean bivalves, which most likely represents a behavioral convergence. G. majianus probably represents some of the earliest bivalves that occupied a relatively deep tier and conducted a siphon-feeding strategy, a functional innovation well prior to the radiation of siphon-feeding infaunal bivalves during the Mesozoic. The presence of G. majianus suggests that large, deep burrowers tended to cause more dramatic impacts in substrate properties than other major Paleozoic bioturbators, and that they could be responsible for the elevated environmental effects of bioturbation as has been observed in strata younger than the latest Silurian.

The zosterophyllopsids had a widespread distribution and constituted a dominant component in many plant assemblages during the Early Devonian. Although a large number of zosterophyllopsids have been documented, knowledge about the paleogeographic distribution of different genera/species remains to be expanded by further fossil evidence. In this article, new material assigned to the genus Gosslingia Heard, 1927 and designated as Gosslingia cf. G. breconensis Heard, 1927 is described from a new locality of the Lower Devonian of Guizhou Province, China. The Guizhou material shows main axes that are pseudomonopodially branched, pseudomonopodial lateral branching systems, subaxillary tubercle branches, circinate apices, elliptical xylem strand, exarch maturation of xylem, and G-type tracheids, and exhibits considerable similarities with the type and only species of Gosslingia, Gosslingia breconensis. Our finding represents the first report of Gosslingia in the South China Block and the most convincing occurrence of this genus outside of Wales, UK. Gosslingia adds to the diversity of genera shared among the Early Devonian floras of South China, western Europe, and North America, along with Distichophytum Magdefrau, Estinnophyton Fairon-Demaret, Zosterophyllum Penhallow, and others, and indicates that the dispersal of early vascular plants among different paleocontinents was more common than previously appreciated.

The timing and pattern of biotic recovery after the Late Ordovician Mass Extinction (LOME) are highly controversial. Here, we conducted a systematic investigation on ichnofossils from the lower Silurian succession of the northwestern Hunan province, middle-upper Yangtze Block, South China. Biotic recovery of marine benthic ecosystems after the LOME was analysed and discussed for the first time using multiple ichnofossil proxies. The vertical distribution and evolutional trends of trace fossil assemblages suggest that biotic recovery was significantly delayed by the widespread anoxia during the latest Hirnantian to middle Aeronian. The recovery displays a stepwise pattern and reached a relatively high stage during the late Aeronian, although a full recovery was generally not achieved during this interval as proposed elsewhere before. There is a sharp decrease in all trace fossil proxies across the Aeronian-Telychian boundary, indicating a resetting of biotic recovery back to initial stages, most likely linked to a re-onset of anoxia in shallow marine settings during the late Aeronian Event. Subsequent recovery generally followed the patterns of late Aeronian, but was hampered by a low nutrient supply during early Telychian. By the beginning of middle Telychian, a full recovery was achieved, ca. 8.8 Ma after the second pulse of the LOME.

Animals breaking away from the sea was a revolutionary event in the evolution of life. Arthropods were the earliest metazoans to move onto land, and although a few Silurian freshwater and/or terrestrial arthropods have been found so far, these records are all from Laurussia. Here, we describe a new freshwater arthropod, Maldybulakia saierensis sp. nov., from the western Junggar, northwest China. Evidence from co‐occurring spores and body fossils of plants is presented in support of a Silurian (Pridoli) age for this new Maldybulakia species, alongside palaeosalinity data in support of our interpretation of it having lived in a freshwater environment. The discovery of this species brings forward the earliest appearance of the Maldybulakia , previously known from the Devonian of Kazakhstan and eastern Australia, to the late Silurian. It is the oldest body fossil record of a putatively freshwater arthropod outside Laurussia, and greatly expands their palaeogeographical distribution. In the middle and late Silurian, the discovery of freshwater arthropods on multiple plates/terranes, as well as their morphological diversity during this period, suggests that arthropods had left the marine environment by the early Silurian or even earlier.

The Lochkovian, Pragian, and basal part of the Emsian, which represent the post-Kwangsian Orogeny strata in the South China Block, are mainly composed of siliciclastic rocks. This lithological composition impedes investigation of Pragian and Lochkovian conodont biostratigraphy in the South China Block, which results in a persistent controversy on the age of relevant lithological units. The present study provides new evidence by reporting for the first time Lochkovian conodonts obtained from the South China Block, specifically the Gaoling Member of the Nahkaoling Formation at the Lingli section, central Guangxi. The conodont fauna, consisting of Pandorinellina exigua lingliensis Lu n. subsp., Pandorinellina exigua exigua, Zieglerodina? tuojiangensis Lu n. sp., Amydrotaxis praejohnsoni, and Eognathodus cf. E. irregularis, places the studied interval of the Gaoling Member in the lower or middle Lochkovian (contingent upon varying definitions for the base of the middle Lochkovian) to lower Pragian. Moreover, Amydrotaxis praejohnsoni, which was reported previously only in North America and eastern Australia, is herein also recorded in the South China Block, and thus may play an important role in intercontinental biostratigraphical correlation. By shedding light on the age of the upper limit of the underlying Lianhuashan Formation at the Lingli section, the present study indicates that the Kwangsian Orogeny ended before the late Lochkovian. This date is slightly earlier than the previously estimated late Lochkovian based on studies of fossil plants from the siliciclastic rocks deposited after the Kwangsian Orogeny.UUID: http://zoobank.org/8010f983-4f6f-43dd-949f-de4653e53d9d

Abundant bivalve trace fossils are found in the Lower Devonian Pingyipu Formation in Guangyuan area, northern Sichuan Province, but systematic ichnological work and behavioral and paleoecological analysis have not been carried out. Close observations on the occurrence, preservation style and morphological features of bivalvian traces provide invaluable information to guide the interpretation of their trace maker, ethological and paleoecological features. Here we carried out sedimentary and systematic ichnology studies on the middle part of the Lower Devonian Pingyipu Formation at the Majia section, Guangyuan area. The results suggest occurrence of bivalvian trace fossils, including Lockeia siliquaria,Protovirgularia rugosa, Ptychoplasma vagans as well as trace fossils of other invertebrate groups such as Cruziana problematica, Dimorphichnus isp.,and Lophoctenium isp. in the lower shoreface to off shore settings. The overall morphological and taphonomic features of the trace fossils suggest that, two major groups, including the cleft-footed（protobranchia）and wedge-footed bivalves occurred in the middle part of the Pingyipu Formation. The protobranchia were deposit-feeding bivalves distributed in the transitional zone and off shore settings. The transition from resting to “escape”state of these bivalves, probably due to erosive events or a higher sedimentation rates, produced the trace fossil Pro. rugosa. The wedge-footed bivalves could be further divided into two groups. The vagile, deposit-feeding type occupied the transitional zone and off shore settings. Their crawling behavior, probably linked to an effort to search for edible material from the sediment generated the trace fossil Pty. vagans. While in the lower shoreface setting, colonies of suspension-feeding bivalves colonized the sediment during relatively tranquil intervals between erosional events. The vertical transition of trace fossil composition in the middle Pingyipu Formation suggests a substitution of Cruziana ichnofacies developed on a relative stiff substrate by the latter Skolithos ichnofacies in an upward shallowing succession.

Testate amoebae, a polyphyletic protist group inhabiting a wide variety of extant ecosystems, have evolved as far back as early Neoproterozoic. However, their fossil record is discontinuous and biased toward empty shells. Here, we report an arcellinid testate amoeba species, Cangwuella ampulliformis gen. nov., sp. nov., from a shallow-marine community in the Early Devonian of Guangxi, southwestern China. With the aid of scanning electron microscopy and X-ray micro-tomography, we find that the shell of our testate amoeba contains some acetabuliform structures. Although such configuration does not match exactly with the known internal structures in extant testate amoebae, our fossils highlight the potential of exploring the ecological relationships between fossil testate amoebae and their associated organisms, and increase our knowledge on the diversity of testate amoebae in Early Devonian environments.