Search

• A palaeohydrological shift documented in early Pliocene in the North China. • A tectonic-scaled 'tripole-like' rainfall pattern existed in Pliocene over East Asia. • Simulated dynamics of Pacific zonal and meridional SST proposed. Considerable uncertainty remains over the nature and causes(s) of East Asian monsoon evolution since the Late Miocene, a significantly warmer period characterized by substantially weaker meridional and zonal Pacific sea surface temperature (SST) gradients than today and therefore regarded as a potential analog for current and future global warming. However, the extent to which these temperature gradients impacted rainfall patterns across East Asia, and particularly the northern extent of the monsoon domain, remains controversial. Here we present the first hydrological record extending back eight million years (Ma) for North China Plain derived from organic biomarkers preserved in a terrestrial sediment sequence. Our record shows a significant increase in monsoon rainfall during the Early Pliocene (∼4.2-4.5 Ma), coincident with strengthening of Pacific meridional and zonal SST gradients, and the eastern equatorial Pacific cold tongue. This marked intensification of the monsoon rainfall in northern China is also observed in paleoclimate archives from southern Asia, but anti-phased with those from central-eastern China (including southern China), indicating a 'tripole-like' rainfall pattern over East Asia. Through a set of climate model experiments, we show that this redistribution of monsoon rainfall across East Asia during the Early Pliocene (5.33-3.6 Ma) was likely due to an equatorward contraction of the western Pacific warm pool, reduced summer convection in the western subtropical Pacific, and the strengthening of the Hadley and Walker circulations. Our study thus highlights the strong influence of Pacific Ocean temperature gradients on East Asian hydroclimate. [ABSTRACT FROM AUTHOR]

Combustion - derived polycyclic aromatic hydrocarbons (PAHs) are frequently used as molecular proxies for wildfire in recent and ancient sediments. Here, we document the abundances of four hydrocarbon compounds, i.e., phenanthrene (Phe), benzo[ e ]pyrene (BeP), benzo[ ghi ]perylene (Bpery), and coronene (Cor), across the Permian–Triassic boundary (PTB) in five marine sections of South China. High values of PAHs are present below the end-Permian mass extinction (EPME) horizon, from the Clarkina changxingensis Zone to the Clarkina yini Zone, suggesting strong perturbations to terrestrial ecosystems predating the marine crisis. PAHs peaked in the uppermost C. yini Zone, correlative with the EPME, reflecting simultaneity of the most severe phases of the terrestrial and marine crises. The proxy records document suitable climatic conditions for wildfires (high p O 2) throughout the P-Tr transition. The results of the present study are also significant in validating the utility of BeP, Bpery, Cor, and BeP/Phe as proxies for terrestrial wildfires in deep-time marine successions. • Polycyclic aromatic hydrocarbons (Phe, BeP, Bpery, Cor) are paleo-wildfire proxies. • These PAHs were identified in five marine P-Tr boundary sections of South China. • Wildfires were common before, during, and after the P-Tr mass extinction. • Atmospheric p O 2 was sufficient during the P-Tr transition to permit wildfires. • Terrestrial habitat devastation contributed to the marine mass extinction. [ABSTRACT FROM AUTHOR]

Testate amoebae (TA) are a common and diverse group of protists and are especially abundant in peatlands. The structure of peatland TA communities is well correlated to surface moisture and water table depth (WTD). For that reason, TA are widely used as proxy indicators in ecological and palaeoecological studies. Peatlands are abundant across Asia, but the diversity and ecology of the TA that inhabit these systems are poorly documented. It is therefore unclear whether TA can be used as palaeohydrological indicators in the manner in which they commonly are in Europe and North-America. There is particular uncertainty as to the efficacy of this approach in the lower latitudes. We compiled existing and new data on testate amoebae from 1124 Sphagnum -dominated samples from 42 individual peatlands covering broad latitudinal (25°–66° N) and longitudinal (68°–129° E) ranges. Using a consensus taxonomic framework, we built a checklist of TA and developed TA-based hydrological transfer functions for Asian peatlands. The results showed that three models, weighted averaging (WA), weighted average partial least squares (WA-PLS), and maximum likelihood (ML), predicted similar WTD values for full samples, while the modern analogue technique (MAT) produced the strongest (R2 boot = 0.58) relationship between observed and estimated water-table depths (WTDs). Removing outlier samples improved the R2 values of observed vs. estimated WTDs, with ML then demonstrating the strongest predictive power (R2 boot = 0.68, RMSEP boot = 8.98 cm). The predictive capability of the developed WTD transfer function is comparable to equivalent models for Europe and North America and thus can be used for palaeohydrological reconstructions for boreal to subtropical peatlands in Asia. • A testate amoebae taxonomic checklist was compiled from Asian peatlands. • We developed continental scale testate amoeba-based hydrological transfer functions. • The water-table depth transfer functions can be used for paleohydrological reconstructions. [ABSTRACT FROM AUTHOR]

• Warm-dry and cold-wet hydroclimate modes were showed according to 18,000-year temperature and DWT changes in Dajiuhu Basin. • Peatland ecology sensitively responded to palaeo-hydroclimatic changes. • More bulliform phytoliths induced by exaggerated plant leaf water loss occurred during warm-dry mid-Holocene. • Plant water regulation, climate, and irradiance showed a synchronous ~1000-yr cycle. Peatland ecosystem processes are strongly influenced by hydrology linked to climate change. However, how transpiration, as major water loss pathway in closed peatland, responds to climate change and then regulates ecosystem water balance that remains poorly understood. Here, we reported an 18,000-year fossil phytolith record from an herbaceous community-dominated mountain peatland in central China to reconstruct climate changes and vegetation evolution and reveal the interactions between regional climate changes and peatland ecosystem. The abundance of bulliform phytoliths—a silicified type of cells that regulate the movements of plant leaves to reduce light exposure and transpiration rate—shows close correlations with the Holocene climate variations with higher bulliform abundance in response to warm-dry climate (11,500–9600 cal yr BP; 7500–3000 cal yr BP) and lower values associated with cold-wet climate (13,000–11,500 cal yr BP; 3000 cal yr BP-present). Spectral analysis reveals that bulliform abundance and reconstructed climate vary with a major ~1000-year periodicity during the Holocene, suggesting a possible causal relationship to solar activity. A high bulliform abundance and warm-dry climate correspond with enhanced solar activity, and vice versa. We interpret that the resultant leaf water deficit resulted from greater light interception, high temperature and drought promoted the production of bulliform cells to fold leaf for water conservation, which is an effective protective mechanism of peatland grasses from the environmental stress. These results expand our understanding of how grass-dominated peatland plant water regulation recorded by bulliform phytoliths responds to solar radiation and local hydroclimate during geological period. [ABSTRACT FROM AUTHOR]

• Land-use change affected testate amoebae and corresponding protozoic silicon pools. • Protozoic Si pools significantly decreased in croplands compared to peatlands. • Drainage of peatlands was found to represent a key factor for decreasing Si pools. • This decrease represents anthropogenic desilication at the microorganismic level. Many peatlands have been damaged by human activities like Sphagnum harvesting and draining reflected in reduced peatland areas and ecosystem functioning. Peatlands generally play an important role in global silicon (Si) cycling and maintain huge numbers of testate amoebae (TA). However, there is a lack of knowledge on (i) the quantity of protozoic Si pools (represented by siliceous shells of TA) in peatlands and (ii) how these pools respond to land use changes caused by human influence. In our study, we quantified protozoic Si pools in the Dajiuhu National Wetland Park, China, with a focus on the comparison between peatland and cropland areas (i.e., former peatland drained for agriculture). We found protozoic Si pools to (i) represent an important biogenic silica fraction in peatlands and (ii) significantly differ between peatlands and croplands with soil moisture as a key factor for protozoic Si pool quantity showing a significant decrease of these pools in drained areas (i.e., in croplands). From our results we concluded the decrease of protozoic Si pools due to land-use change to represent another example (apart from the loss of phytogenic Si) for anthropogenic desilication in agricultural biogeosystems in general. [ABSTRACT FROM AUTHOR]

• First evidence of T-J boundary wildfires outside Central Atlantic Magmatic Province. • Lipid profiles document three wildfire episodes during T-J transition in South China. • PPAH index documents provenance from alkyl-PAHs by pyrolytic (combustion) reactions. • Warmer, drier conditions caused by CAMP set stage for TJB wildfires in South China. • Regional aridification related to southward paleo-ITCZ shift was immediate trigger. Emplacement of the Central Atlantic Magmatic Province (CAMP) during the Triassic-Jurassic (Tr-J) transition is believed to have indirectly increased wildfire frequency through climatic warming and drying. To date, evidence for wildfires has come mainly from within the CAMP region. Here, we present biomarker evidence for wildfires in the form of polycyclic aromatic hydrocarbons (PAHs) in two terrestrial Triassic-Jurassic boundary sections in the Sichuan Basin, southwestern China. Pyrolytic PAHs of probable wildfire origin identified in these sections include pyrene, benzofluoranthene, benzo[e]pyrene, indeno[1,2,3-cd]pyrene, benzo[ghi]perylene, and coronene. Sharp increases in the abundances of pyrolytic PAHs normalized to total organic carbon were found during the Rhaetian Stage (R1 and R2) and at the Tr-J boundary. The ratios of pyrolytic PAHs (PPAHs) to methylated homologues document the combustion origin of PPAHs from methylated PAHs during these intervals of increased wildfire frequency. The abundances of oxygenated PAHs with furan structure show the same stratigraphic trend, testifying to enhanced soil erosion or weathering that may have resulted from a reduction of vegetative cover. Although CAMP-induced climate changes probably set the stage for more frequent wildfires in South China, the immediate trigger was probably a southward shift of the paleo-Intertropical Convergence Zone (ITCZ). These observations suggest a complex feedback involving climatic warming, precipitation and evapo-transpiration, vegetation density, and wildfire prevalence during the Tr-J transition. [ABSTRACT FROM AUTHOR]

C 4 -grasslands are known to have first expanded globally in the Late Miocene, and recent research has hinted at a second expansion phase during the Early Pliocene; however, the geographic extent of this second event and its driving force are debated. In this study, we present organic carbon-isotopic evidence from a high-resolution drillcore in North China spanning the interval from ∼8.0 Ma to the present. A prominent positive δ13C org shift at ∼4.1 Ma marks C 4 -grassland expansion on the North China Plain, and rapid oscillations of >6‰ from ∼3.2 to 2.2 Ma imply large shifts between C 3 - and C 4 -dominated floras. Our δ13C org profile mirrors carbon isotope shifts in loess-red clay deposits of the Chinese Loess Plateau, confirming the regional nature of this event. Furthermore, coeval carbon isotope records from Africa, North America, and South America provide evidence that the Early Pliocene C 4 -grassland expansion was global in scale and temporally distinct from the Late Miocene event. Whereas the Late Miocene event may have been related to aridification and altered fire regimes, this mechanism cannot account for the Early Pliocene expansion owing to contemporaneous increases in humidity at many Northern Hemisphere sites. We hypothesize that C 4 -grassland expansion in the Early Pliocene was triggered by falling atmospheric CO 2 levels, as evidenced by multiple p CO 2 proxy records and supported by quantum photosynthetic efficiency modeling. • Organic carbon isotope records from North China Plain show a significant expansion of C 4 grasslands at ∼4 Ma. • Early Pliocene C 4 grassland expansion also documented from Pakistan, East Africa, and North and South America. • Early Pliocene C 4 grassland expansion probably driven by declining atmospheric p CO 2 , not aridification. • Control by declining atmospheric p CO 2 supported by quantum photosynthetic efficiency modeling. • Contraction of C 4 grasslands in North China since ∼2.2 Ma due to cooling and strengthening of the East Asian Winter Monsoon. [ABSTRACT FROM AUTHOR]

The distribution of archaeal ether lipids is thought to be governed by salinity in hypersaline and marine environments due to differences in their biological sources. However, little is known about their source and relationship with salinity in lacustrine environments. To explore this, we analyzed the distribution of specific archaeal lipids (isoprenoid GDGTs and diethers) of 11 ponds along a salinity gradient (0.8‰ to 279‰) in Inner Mongolia, NE China. Functional gene mcrA and compound-specific stable carbon isotope data were used to explore the biological source(s) of archaeal diether and tetraether lipids. Both lipid- and DNA-based methods showed methanogens to be abundant in ponds, which is consistent with the dominance of GDGT-0 relative to other isoprenoid GDGTs as well as the occurrence of archaeol (C 20 /C 20 DGD), hydroxyarchaeol and the mcrA gene. However, the occurrence of the extended archaeol (C 20 /C 25 DGD) also suggests the presence of Halobacteriales, non-halophilic methanogens and halophilic methanogens. This means that the biological sources of archaeal diethers and tetraethers are complicated. We subsequently evaluated the applicability of TEX 86 temperature and ACE salinity proxies in these settings; however, due to the mixed sources of archaeal diethers and tetraethers, these proxies are not applicable in these ponds and it appears that salinity is not the dominant control on archaeal ether lipid distributions in these saline ponds. [ABSTRACT FROM AUTHOR]

The ocean has been a regulator of climate change throughout the history of Earth. One key mechanism is the mediation of the carbon reservoir by refractory dissolved organic carbon (RDOC), which can either be stored in the water column for centuries or released back into the atmosphere as CO 2 depending on the conditions. The RDOC is produced through a myriad of microbial metabolic and ecological processes known as the microbial carbon pump (MCP). Here, we review recent research advances in processes related to the MCP, including the distribution patterns and molecular composition of RDOC, links between the complexity of RDOC compounds and microbial diversity, MCP-driven carbon cycles across time and space, and responses of the MCP to a changing climate. We identify knowledge gaps and future research directions in the role of the MCP, particularly as a key component in integrated approaches combining the mechanisms of the biological and abiotic carbon pumps for ocean negative carbon emissions., (© 2024. Springer Nature Limited.)

The scarcity of proxies and calibration models for quantitatively reconstructing millennial timescale seasonal temperature tremendously constraints our understanding of the Holocene thermal variation and its driven mechanisms. Here, we established two global warm-season temperature models by applying deep learning neural network analysis to the branched tetraether membrane lipids originating from surface soil and lacustrine sediment bacteria. We utilized these optimal models in global well-dated lacustrine, peatland, and loess profiles covering the Holocene. All reconstructions of warm-season temperatures, consistent with climate model simulations, indicate cooling trends since the early Holocene, primarily induced by decreased solar radiation in the Northern Hemisphere due to the precession peak at the early. We further demonstrated that the membrane lipids can effectively enhance the future millennial seasonal temperature research, including winter temperatures, without being restricted by geographical location and sedimentary carrier., (Copyright © 2024 Science China Press. Published by Elsevier B.V. All rights reserved.)

'Mass extinctions' have been a hot topic for several decades. What triggers a mass extinction? How does a mass extinction impact the evolution of life? How does our ecosystem recover after a mass extinction? These questions attracted the interest of both scientists and the public alike. NSR spoke to two renowned researchers in the field of mass extinctions: Prof. Douglas H. Erwin from the National Museum of Natural History of the USA, and Prof. Shuzhong Shen from Nanjing University, China. Prof. Erwin has been interested in the end-Permian mass extinction since graduate school. He has worked on a variety of problems, from Permian gastropod systematics to the origin of animals. Currently his work focuses on the nature of evolutionary novelty and innovation. Prof. Shen's research career is centered upon the end-Permian mass extinction, Permian stratigraphy and global correlations, with taxonomic expertise on brachiopods and conodonts. The International Commission on Stratigraphy recognizes his outstanding singular contribution to stratigraphy and awarded him the ICS Stratigraphy Medal in 2019., (© The Author(s) 2023. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd.)

Competing Interests: Conflict of interest The authors declare that they have no conflict of interest.

Direct evidence of intense chemical weathering induced by volcanism is rare in sedimentary successions. Here, we undertake a multiproxy analysis (including organic carbon isotopes, mercury (Hg) concentrations and isotopes, chemical index of alteration (CIA), and clay minerals) of two well-dated Triassic-Jurassic (T-J) boundary sections representing high- and low/middle-paleolatitude sites. Both sections show increasing CIA in association with Hg peaks near the T-J boundary. We interpret these results as reflecting volcanism-induced intensification of continental chemical weathering, which is also supported by negative mass-independent fractionation (MIF) of odd Hg isotopes. The interval of enhanced chemical weathering persisted for ~2 million years, which is consistent with carbon-cycle model results of the time needed to drawdown excess atmospheric CO 2 following a carbon release event. Lastly, these data also demonstrate that high-latitude continental settings are more sensitive than low/middle-latitude sites to shifts in weathering intensity during climatic warming events., (© 2022. The Author(s).)

Paleozoic and Precambrian sedimentary successions frequently contain massive dolomicrite [CaMg(CO 3 ) 2 ] units despite kinetic inhibitions to nucleation and precipitation of dolomite at Earth surface temperatures (<60 °C). This paradoxical observation is known as the "dolomite problem." Accordingly, the genesis of these dolostones is usually attributed to burial-hydrothermal dolomitization of primary limestones (CaCO 3 ) at temperatures of >100 °C, thus raising doubt about the validity of these deposits as archives of Earth surface environments. We present a high-resolution, >63-My-long clumped-isotope temperature (T Δ47 ) record of shallow-marine dolomicrites from two drillcores of the Ediacaran (635 to 541 Ma) Doushantuo Formation in South China. Our T ∆47 record indicates that a majority (87%) of these dolostones formed at temperatures of <100 °C. When considering the regional thermal history, modeling of the influence of solid-state reordering on our T Δ47 record further suggests that most of the studied dolostones formed at temperatures of <60 °C, providing direct evidence of a low-temperature origin of these dolostones. Furthermore, calculated δ 18 O values of diagenetic fluids, rare earth element plus yttrium compositions, and petrographic observations of these dolostones are consistent with an early diagenetic origin in a rock-buffered environment. We thus propose that a precursor precipitate from seawater was subsequently dolomitized during early diagenesis in a near-surface setting to produce the large volume of dolostones in the Doushantuo Formation. Our findings suggest that the preponderance of dolomite in Paleozoic and Precambrian deposits likely reflects oceanic conditions specific to those eras and that dolostones can be faithful recorders of environmental conditions in the early oceans., Competing Interests: The authors declare no competing interest.

Speleothem oxygen isotope records have revolutionized our understanding of the paleo East Asian monsoon, yet there is fundamental disagreement on what they represent in terms of the hydroclimate changes. We report a multiproxy speleothem record of monsoon evolution during the last deglaciation from the middle Yangtze region, which indicates a wetter central eastern China during North Atlantic cooling episodes, despite the oxygen isotopic record suggesting a weaker monsoon. We show that this apparent contradiction can be resolved if the changes are interpreted as a lengthening of the Meiyu rains and shortened post-Meiyu stage, in accordance with a recent hypothesis. Model simulations support this interpretation and further reveal the role of the westerlies in communicating the North Atlantic influence to the East Asian climate., (Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

The nature and extent to which hydrological changes induced by the Asian summer monsoon affected key biogeochemical processes remain poorly defined. This study explores the relationship between peatland drying and carbon cycling on centennial timescales in central China using lipid biomarkers. The difference between peat n-alkane δ 2 H and a nearby stalagmite δ 18 O record reveals that intervals of prominent peatland drying occurred during the mid-Holocene. Synchronous with these drier conditions, leaf wax δ 13 C values show large negative excursions, with the utilization of CO 2 respired from the peatland subsurface for plant photosynthesis being a possible mechanism. Crucially, successive drying events appear to have had a cumulative impact on the susceptibility of peat carbon stores to climate change. Concurrently, bacterially derived hopane δ 13 C values suggest the occurrence of enhanced methane oxidation during the drier periods. Collectively, these observations expand our understanding of how respiration and degradation of peat are enhanced during drying events.

The marine nitrogen cycle is dominated by redox-controlled biogeochemical processes and, therefore, is likely to have been revolutionised in response to Earth-surface oxygenation. The details, timing, and trajectory of nitrogen cycle evolution, however, remain elusive. Here we couple nitrogen and carbon isotope records from multiple drillcores through the Rooihoogte-Timeball Hill Formations from across the Carletonville area of the Kaapvaal Craton where the Great Oxygenation Event (GOE) and its aftermath are recorded. Our data reveal that aerobic nitrogen cycling, featuring metabolisms involving nitrogen oxyanions, was well established prior to the GOE and that ammonium may have dominated the dissolved nitrogen inventory. Pronounced signals of diazotrophy imply a stepwise evolution, with a temporary intermediate stage where both ammonium and nitrate may have been scarce. We suggest that the emergence of the modern nitrogen cycle, with metabolic processes that approximate their contemporary balance, was retarded by low environmental oxygen availability.

Extreme hydrologic events such as storms and floods have the potential to severely impact modern human society. However, the frequency of storms and their underlying mechanisms are limited by a paucity of suitable proxies, especially in inland areas. Here we present a record of speleothem magnetic minerals to reconstruct paleoprecipitation, including storms, in the eastern Asian monsoon area over the last 8.6 ky. The geophysical parameter IRM soft-flux represents the flux of soil-derived magnetic minerals preserved in stalagmite HS4, which we correlate with rainfall amount and intensity. IRM soft-flux exhibits relatively higher values before 6.7 ky and after 3.4 ky and lower values in the intervening period, consistent with regional hydrological changes observed in independent records. Abrupt enhancements in the flux of pedogenic magnetite in the stalagmite agree well with the timing of known regional paleofloods and with equatorial El Niño-Southern Oscillation (ENSO) patterns, documenting the occurrence of ENSO-related storms in the Holocene. Spectral power analyses reveal that the storms occur on a significant 500-y cycle, coincident with periodic solar activity and ENSO variance, showing that reinforced (subdued) storms in central China correspond to reduced (increased) solar activity and amplified (damped) ENSO. Thus, the magnetic minerals in speleothem HS4 preserve a record of the cyclic storms controlled by the coupled atmosphere-oceanic circulation driven by solar activity., Competing Interests: The authors declare no conflict of interest.

Molecular oxygen (O2) is, and has been, a primary driver of biological evolution and shapes the contemporary landscape of Earth's biogeochemical cycles. Although "whiffs" of oxygen have been documented in the Archean atmosphere, substantial O2 did not accumulate irreversibly until the Early Paleoproterozoic, during what has been termed the Great Oxygenation Event (GOE). The timing of the GOE and the rate at which this oxygenation took place have been poorly constrained until now. We report the transition (that is, from being mass-independent to becoming mass-dependent) in multiple sulfur isotope signals of diagenetic pyrite in a continuous sedimentary sequence in three coeval drill cores in the Transvaal Supergroup, South Africa. These data precisely constrain the GOE to 2.33 billion years ago. The new data suggest that the oxygenation occurred rapidly-within 1 to 10 million years-and was followed by a slower rise in the ocean sulfate inventory. Our data indicate that a climate perturbation predated the GOE, whereas the relationships among GOE, "Snowball Earth" glaciation, and biogeochemical cycling will require further stratigraphic correlation supported with precise chronologies and paleolatitude reconstructions.

Oxygenation has widely been viewed as a major factor driving the emergence and diversification of animals. However, links between early animal evolution and shifts in surface oxygen levels have largely been limited to extrapolation of paleoredox conditions reconstructed from unfossiliferous strata to settings in which contemporaneous fossils were preserved. Herein, we present a multi-proxy paleoredox study of late Ediacaran (ca. 560-551 Ma) shales hosting the Miaohe Konservat-Lagerstätte of South China and, for comparison, equivalent non-fossil-bearing shales at adjacent sections. For the fossiliferous strata at Miaohe there is geochemical evidence for anoxic conditions, but paleontological evidence for at least episodically oxic conditions. An oxygen-stressed environment is consistent with the low diversity and simple morphology of Miaohe Biota macrofossils. However, there is no evidence for euxinic (anoxic and sulphidic) conditions for the fossiliferous strata at Miaohe, in contrast to adjacent unfossiliferous sections. Our results indicate that Ediacaran marine redox chemistry was highly heterogeneous, even at the kilometre-scale. Therefore, our study provides direct-rather than inferred-evidence that anoxia played a role in shaping a landmark Ediacaran ecosystem. If the anoxic conditions characteristic of the studied sections were widespread in the late Neoproterozoic, environmental stress would have hindered the development of complex ecosystems.

Testate amoebae are a group of shelled protozoa that occur in high density populations in wet environments. More than 1900 testate amoebae species or subspecies have been reported in published literature over the last 200 years, from many regions of the world. Testate amoebae are classified as Lobosea or Filosea respectively, according to the presence of lobose or filiform pseudopodia. Testate amoebae have proved an interesting group of indicator organisms in palaeoenvironmental studies and have also been used as bioindicators of human impact on ecosystems. Until recently, the testate amoebae of China were unknown to most western scientists, but our knowledge has improved greatly over the past 20 years. This paper summarizes the testate amoebae research in China along with relevant data from other countries in Asia, and provides the necessary context for future research., (Published by Elsevier GmbH.)

The morphology of a new testate amoeba Pentagonia zhangduensis nov. spec. was investigated using light and scanning electron microscopy. The new species was discovered in the sediments of Lake Zhangdu, Hubei Province, China. The low coefficients of variation and normal size frequency distribution suggest that P. zhangduensis is a size-monomorphic species. P. zhangduensis differs from the one other species in this genus (P. maroccana), by its larger size and its quadrangular cross section with two parallel longitudinal ridges on each of the two flattened sides of the test.

Microbial expansion following faunal mass extinctions in Earth history can be studied by petrographic examination of microbialites (microbial crusts) or well-preserved organic-walled microbes. However, where preservation is poor, quantification of microbial communities can be problematic. We have circumvented this problem by adopting a lipid biomarker-based approach to evaluate microbial community changes across the Permo/Triassic (P/Tr) boundary at Meishan in South China. We present here a biomarker stratigraphic record showing episodic microbial changes coupled with a high-resolution record of invertebrate mass extinction. Variation in the microbial community structure is characterized by the 2-methylhopane (2-MHP) index (a ratio of the abundance of cyanobacterial biomarkers to more general bacterial biomarkers). Two episodes of faunal mass extinction were each preceded by minima in the 2-MHP index, followed by strong maxima, likely reflecting microbial responses to the catastrophic events that caused the extinction and initiated ecosystem changes. Hence, both cyanobacterial biomarker and invertebrate fossil records provide evidence for two episodes of biotic crisis across the P/Tr boundary.