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The end-Guadalupian mass extinction (i.e., pre-Lopingian crisis) has been recognized as a major biotic crisis in Earth's history for nearly three decades. As more and more evidence has been gathered in recent years, our understanding of this event has been enhanced and to some extent changed. Fossil evidence suggests that the end-Guadalupian mass extinction is not as severe as originally thought, and only happened at the community level and was taxonomically selective. The turnovers of major marine fossil groups occurred at different temporal levels, therefore the total duration is relatively extended, especially compared to the sudden end-Permian mass extinction. The nature of the turnover of terrestrial organisms around the Guadalupian-Lopingian boundary (GLB) is so far poorly known. Biostratigraphic constraints suggest that it most likely occurred in the latest Capitanian-earliest Wuchiapingian, a stratigraphic interval between the conodont Jinogondolella xuanhanensis and Clarkina dukouensis zones. Substantial environmental changes coincided with the end-Guadalupian mass extinction, including the largest sea-level fall, and major climate and ocean chemistry (e.g., δ13Ccarb, δ34S, and 87Sr/86Sr) changes. Considering evidence available within a unified temporal framework, the largest regression of the Paleozoic and Emeishan LIP (Large Igneous Province) volcanism are the most likely primary triggers, while other previously suggested causes such as long-term cooling, rapid fluctuations in seawater temperatures, ocean anoxia, explosive volcanism and cooling, and methane outburst with low atmospheric oxygen are either not supported by direct evidence, or were only secondary causes.

The Sakmarian Stage represents a critical time interval because the Late Paleozoic Ice Age reached its acme during this time. After extensive studies, we herein use the First Appearance Datum (FAD) of the conodont Mesogondolella monstra within the lineage from M. uralensis -> M. monstra -> M. manifesta at Bed 26/3 of the Usolka section in the southern Urals, Russia, as the primary signal for the base-Sakmarian GSSP. The first occurrence of the conodont Sweetognathus binodosus within the lineage from Sw. off. merrilli -> Sw. binodosus is used as an auxiliary marker for the base of the Sakmarian Stage. An extrapolated age for this GSSP is 293.52 +/- 0.17 Ma produced by a Monte Carlo simulation based on two ash beds dated by chemical abrasion isotope dilution thermal ionization mass spectrometry (CA-ID-TIMS). The Sr-87/Sr-86 isotopic value based on conodont apatite for the base of the Sakmarian Stage is approximately 0.70787. Two minor negative excursions in delta(13)C(carb )are present at the boundary levels and the upper one is consistent with the GSSP level. The documentation of fusulinaceans, ammonoids, brachiopods and palynology also aid intercontinental and marine-terrestrial correlation. The Usolka section meets the requirements for the GSSP and a monument has been established; correlation with sections in North America and South China is also well documented.

The Lopingian is the uppermost series of the Paleozoic and it is bracketed by two major biological events, including the pre-Lopingian crisis and the end-Permian mass extinction (EPME). A high resolution temporal framework is essential to understand the patterns and causes of the extinction. Lopingian strata of South China have been intensively studied because three GSSPs have been defined in the region. Based on the review and updates to data from the Shangsi section as well as correlation with the Meishan section, the time framework for the Lopingian is revised, including biostratigraphy, chemostratigraphy, magnetostratigraphy, cyclostratigraphy and geochronology. The temporal framework is constrained by both precise geochronologic data and a high resolution conodont succession, and provides the possibility that the current high resolution marine international standard can also be applied to nonmarine strata by means of geochronology, magnetostratigraphy and cyclostratigraphy. The entire Lopingian high resolution conodont succession is for the first time, since the Lopingian Series was adopted as the international standard, recognized at a single section in South China and the succession correlates very well with the Lopingian GSSP sections at Penglaitan and Meishan. The Permian-Triassic boundary (PTB) of the Shangsi section is constrained to the basal 6 cm interval of Bed 28b in view of ammonoids, bivalves, conodonts, U-Pb ages and the EPME. The mass extinction interval is between Bed 27 and lower Bed 28a according to the EPME pattern at the Shangsi section, and the alternative interval between extinct Permian species and new Triassic species is from upper Bed 28a to lower Bed 28b. Unitary Association (UA) analysis of Lopingian conodonts reveals 15 unitary association zones (UAZs) based on seven important Lopingian sections of South China. Most of the UAZs correlate well with the standard biozonation, except for UAZ 3 to UAZ 5 and UAZ 12. The correspondence between UAZs and standard conodont biozones at the Shangsi section provides a practical example to understand controls on conodont UAZ determination. The Lopingian conodont succession is temporally calibrated by geochronologic ages, identified 405-kyr eccentricity cycles, and a Monte Carlo analysis at the Shangsi and Meishan sections. Updated ages for the base of the Lopingian and base of the Changhsingian are provided.

Although the precise age and magnitude of the end-Guadalupian biodiversity crisis is still debated, this “mass” extinction has been customarily linked with the onset of massive volcanism in the Emeishan Large Igneous Province (ELIP) in south China. The onset of ELIP eruptive activity at least partly coincides in time with episodes of regional subsidence interrupting the predominant regime of carbonate platforms during Capitanian times. Here, we present a strikingly similar but younger (early Wuchiapingian) subsidence episode from the Pingtang syncline in southern Guizhou, termed the Mapojiao Event. Shallow-marine, light-grey, thick-bedded bioclastic limestone of the Wuchiaping Formation (Unit A) are overlain by deep-marine radiolarian-sponge spicule, thin-bedded black limestone (Unit B). The latter is followed by volcaniclastic distal turbidites (Unit C). The base of the next overlying unit consists of cherty, nodular limestone (Unit D) rich in radiolarians and sponge spicules, whose respective abundances decline up-ward within a few meters. Concomitant replacement by a shallow marine benthic fauna documents the uplift that terminates the event. A total of five index species of Clarkina conodonts indicating an early Wuchiapingian age were obtained from Units A and B. Brachiopods of Wuchiapingian age were also documented in units A, B and D. Compilation of drowning events in the Guadalupian-Lopingian (G-L) interval suggests clustering into three episodes; 1: middle Capitanian, 2: possibly latest Capitanian, 3: early Wuchiapingian. The first drowning event is overlain by ELIP volcanics in sections near the center of the volcanic province. In peripheral areas, the first drowning is intercalated within carbonate platforms (e.g. Maoershan). A second drowning event cannot be excluded close to G-L boundary but it is obscured by the unconformity associated with an eustatic regression and by ambiguous conodont age control. Overlying this unconformity, the Wangpo Shale, which contains ELIP-derived volcanic materials, rests on the first (e.g. in Chaotian) drowning event. The striking similarities of the facies architecture shared by the first and third drowning events suggest a similar driving mechanism. Hence, we propose that the Mapojiao Event represents the youngest, early Wuchiapingian, burst of ELIP eruptive activity. There is no one-to-one correlation between these episodes related to ELIP eruptive activity and extinction phases of marine clades. Only the end-Guadalupian extinction has been correlated with the first eruptive episode. In marked contrast, the newly discovered Mapojiao drowning episode occurred within a diversification phase, which undermines any causal relations between the younger phases of ELIP volcanism and additional extinctions.

A new carbon isotope excursion was recovered from the Capitanian marine carbonates at the Rencunping (RCP) section of South China. Significantly, a pronounced excursion with elevated δ13Ccarb values over +5‰ was coeval with the conodont Jinogondolella prexuanhanensis Zone and resembles the Kamura event recorded in Tethys. The excursions in δ13Ccarb, constrained by conodont biostratigraphy, however, present inconsistent carbon cycle behaviors, especially between the separated basins in South China, and evidently reflect regional litho-facies controls. In addition, a transitional environment in association with a fall in sea level, was recovered from deposits of anoxic cherty carbonates subsequent to shallow-water carbonates around the positive excursion in δ13Ccarb. Accordingly, instead of this being a signal of global-scale climatic cooling, we suggest that the positive excursion in δ13Ccarb can be attributed to eutrophication effects regionally along a continental shelf. In this scenario, the increasing dissolved O2 level in the mixing zone that induced by the initial sea-level fall will efficiently impede denitrification and increase the bio-available N in N:P ratio to satisfy the demands of primary producers in surface waters. Subsequently, deposits of shallow-water carbonates comprising calcareous algae and massively-bedded lime muds accumulated widely around South China. These deposits appear to represent an unusual environment and ecosystem fertilized, perhaps, by the weathering products from the earliest stages of volcanism prior to the main Emeishan flood basalt eruptions at the Guadalupian-Lopingian boundary (GLB)., NASA Astrobiology Institute (Award NNA13AA90A)

Nearly all extant animal phyla first appeared during the Ediacaran-Cambrian transition. A revolution in primary producer ecology and marine productivity has been proposed as a bottom-up ecological driver for this rapid diversification of metazoans. However, the control(s) driving the evolution of primary producers and primary productivity around the Ediacaran-Cambrian transition, and their potential relationship to the Cambrian Explosion, are not fully understood. In this study, we measured the nitrogen content and the nitrogen isotopic composition of kerogen in the Piyuancun and Hetang Formations, using samples collected from the Chunye-1 well, on the Lower Yangtze Block in western Zhejiang. Our isotope results suggest that nitrate was the dominant N source fueling primary productivity during deposition of the entire Piyuancun Formation and lower Hetang Formation, with only a minor contribution from N 2 fixation. Quantitative reconstructions of paleoproductivity based on organic carbon and pyrite content and sedimentation rate indicate that productivity either stayed the same or increased during the transition from the Piyuancun Formation to the overlying Hetang Formation. Thus, fixed N availability was not the ultimate factor limiting primary productivity during the Ediacaran-Cambrian transition. Combining our data with published nitrogen isotope records from the Early-Middle Ediacaran to Cambrian Stage 4 suggests that NO 3 − was the dominant N species fueling phytoplanktonic productivity during the broad Cambrian Explosion interval, from its earliest roots in the Ediacaran through the main episode in Cambrian Stage 3. Eukaryotes lack the ability to fix nitrogen, and preferentially assimilate nitrate. The NO 3 − -dominated euphotic zone from the Early-Middle Ediacaran to Cambrian Stage 3 may have promoted the radiation of relatively large eukaryote phytoplankton, which may have been an important driver of early animal diversification.

A continuous strontium isotope profile with high-resolution sampling is desirable to calibrate multiple global events, realize temporal correlation among different continents, and understand tectonic history of the Permian Period. In this paper, we analyzed 90 micritic limestone samples from South China and 7 samples from Iran, with the aim to gain new 87Sr/86Sr data and obtain a curve of Sr isotopes for the Permian. The concentrations of Mg, Fe, Mn, and Sr are used to discriminate possible diagenesis of the samples. A comparison of those 87Sr/86Sr values between South China and southern Urals confirms that Sr-isotope proxy has the potential to be used for time calibration and correlation in regions where biostratigraphic or radiometric markers are not available. The 87Sr/86Sr curve obtained in this study shows a trend comparable with the LOcally WEighted Scatterplot Smoothing (LOWESS) regression curve from the previous studies. A continuous decline trend from the latest Carboniferous to late Guadalupian was shown, and the lowest 87Sr/86Sr values in the late Capitanian was constrained within the interval from the conodont Jinogondolella shannoni/J. altudaensis to J. xuanhanensis zones. It is followed by an increasing trend to more radiogenic values in the Lopingian with a minor fluctuation in the early Wuchiapingian. We consider that mid-ocean ridge spreading and increasing continental weathering during the transition from convergence to the breakup of Pangea as the dominant factors driving the changes of the seawater Sr isotope ratios.

Carbon isotope compositions of carbonates (δ13Ccarb) document a new 3.5‰ CIE toward lower values concomi- tant with an Emeishan Large Igneous Province (ELIP)-related drowning event (Mapojiao Event, southern Gui- zhou) during the early Wuchiapingian. Organic carbon isotope data (δ13Corg) have a 2‰ shift toward higher values across the drowning event, showing decoupling with the δ13Ccarb evolution. Rock-Eval and palynofacies analyses suggest an elevated flux of terrestrial organic matter (OM) during the drowning episode. Therefore, the decoupling between δ13Ccarb and δ13Corg is best explained by the mixing of different organic carbon pools in the δ13Corg curve. Strontium isotope data (87Sr/86Sr) also show a transient shift from 0.70715 to 0.70694 asso- ciated with this early Wuchiapingian carbon isotope excursion (CIE), which is superimposed on the late Permian prolonged global rising trend. This short-lived 87Sr/86Sr excursion is best interpreted as an enhanced hydrother- mal flux related to a short pulse of ELIP-related volcanism. Comparison of the Mapojiao Event with other C isotope records from South China and other parts of Tethys re- veals substantial discrepancies. Moreover, older Capitanian CIEs concomitant with ELIP-related drownings are also not laterally reproducible in time. The local distribution of CIEs across Guadalupian-Lopingian (G-L) interval indicates the influence of local factors such as bathymetry and increased burial rate of terrestrial OM, rather than perturbations in the global carbon cycle to due volcanism. This prevents the C isotope record to be used as a global correlation tool during Capitanian and Wuchiapingian times. Comparison of palaeobiodiversity changes with perturbations in C isotope compositions across the G-L interval shows that only the oldest CIE was associated with a modest extinction event as documented in South China. Hence, this study undermines any systematic cou- pling and causal relation between extinctions and iterative perturbations of the C isotope record during the G-L interval.

Earth's penultimate icehouse (ca. 340-285 Ma) was a time of low atmospheric pCO(2) and high pO(2), formation of the supercontinent Pangaea, dynamic glaciation in the Southern Hemisphere, and radiation of the oldest tropical rainforests. Although it has been long appreciated that these major tectonic, climatic, and biotic events left their signature on seawater Sr-87/Sr-86 through their influence on Sr fluxes to the ocean, the temporal resolution and precision of the late Paleozoic seawater Sr-87/Sr-86 record remain relatively low. Here we present a high-temporal-resolution and high-fidelity record of Carboniferous-early Permian seawater Sr-87/Sr-86 based on conodont bioapatite from an open-water carbonate slope succession in south China. The new data define a rate of long-term rise in Sr-87/Sr-86 (0.000035/m.y.) from ca. 334-318 Ma comparable to that of the middle to late Cenozoic. The onset of the rapid decline in Sr-87/Sr-86 (0.000043/m.y.), following a prolonged plateau (318-303 Ma), is constrained to ca. 303 Ma. A major decoupling of Sr-87/Sr-86 and pCO(2) during 303-297 Ma, coincident with the Paleozoic peak in pO(2), widespread low-latitude aridification, and demise of the pan-tropical wetland forests, suggests a major shift in the dominant influence on pCO(2) from continental weathering and organic carbon sequestration (as coals) on land to organic carbon burial in the ocean.

A major discrepancy for the age of the Selong Group from middle Cisuralian (Early Permian) to Changhsingian resulted from previous reports of Sakmarian, Kungurian and Guadalupian (Middle Permian) conodonts and Lopingian (Late Permian) brachiopods. Recently, Cisuralian and Guadalupian conodonts were reported again from the Selong Group and the basal part of the Kangshare Formation at the Selong section, but the age discrepancy remains. We present our conodont materials based on large samples collected from the Selong Group and our interpretation based on identifications using a sample population approach. Three conodont zones are recognized in our re-investigation of the upper part of the Selong Group. They include the Vjalovognathus sp., the Mesogondolella hendersoni, and the M. sheni zones, in ascending order. These zones are overlain by the basal Triassic Hindeodus parvus Zone and the Otoceras woodwardi Zone. Our reassessment of conodonts reported by previous studies from Selong and nearby sections suggest that all specimens consistently point to a Lopingian age; the upper part of the Selong Group is latest Changhsingian in age based on the presence of Clarkina orchardi and Mesogondolella sheni. Previously reported early Cisuralian and Guadalupian conodonts are misidentified using a form species concept. A hiatus may be present at the erosional surface between the Selong Group and the Waagenites Bed of the basal part of the Kangshare Formation. However, the hiatus is minimal because conodont and brachiopod assemblages above and below this surface are very similar, and it results from a latest Changhsingian transgression just before the extinction that follows a global latest Changhsingian regression. There is a distinct rapid end-Permian mass extinction at Selong within the Waagenites Bed, as indicated by the disappearances of all benthic brachiopods, rugose corals and Permian bryozoans. The burst of Clarkina species in the Waagenites Bed and throughout the entire Lower Triassic at Selong is interpreted as a southward migration of equatorial conodont animals associated with the rapid global warming beginning at the end of the Permian. The cool- or cold-water species of Mesogondolella, in the upper part of the Selong Group and the basal part of the Kangshare Formation, are representative of the uppermost Permian in the bipolar/bi-temperate cold-water province and are not reworked from the underlying Selong Group or any other unknown Cisuralian or Guadalupian deposits.

The paleogeographic evolution of the North Qiangtang Block during the Middle and Late Permian has been a contentious issue in recent decades. In this study, the Permian foraminiferal faunas were studied from the Raggyorcaka and Wangka areas in northern and eastern Tibet. The foraminifera from the Xueyuanhe Formation in the Raggyorcaka area suggest a Changhsingian rather than a Guadalupian (Middle Permian) age, as previously determined. A review of Permian strata in the North Qiangtang Block confirms the widespread onset of the Lopingian (Late Permian) paralic sedimentary facies containing gigantopterid plant fossils and the fusuline Palaeofusulina fauna, which lies unconformably over the different pre-Lopingian strata. The similar Lopingian facies and pronounced unconformity across the North Qiangtang and Simao blocks are interpreted as the initial collision between the Simao/Indochina and the South China blocks.

A 66 cm thick volcanic ash fall tuff occurring within a thick coal deposit and containing a paleobotanical fossil lagerstatte in the Wuda coal district of North China has been dated as 298.34 ± 0.09 Ma. The fossil flora in the tuff indicates a latest Carboniferous to earliest Permian age and is thus in agreement with the radioisotopic age of earliest Permian, Asselian, age. This bed supplies a well-defined position of the Carboniferous–Permian boundary near the northern edge of the North China Block. The tuff occurs in the top of the Taiyuan Formation and several meters below the base of the Shansi (= Shanxi) Formation. These beds were traditionally considered late Carboniferous to early Permian in age. Our results demonstrate that the Taiyuan Formation is time transgressive and its age has to be revised for the northern part of the North China Block.

The early Paleozoic sediments document two major biological events: the Great Ordovician Biodiversification Event (GOBE) and Late Ordovician mass extinction (LOME). Many investigations have focused on taxonomic richness patterns during these major diversification and extinction events, providing insights into their timings and potential causes. However, the coarse temporal resolutions used in previous investigations hampered their ability to document fine-scale patterns. To address these issues, we employed CONOP analysis to data collected from a large suite of southern Chinese stratigraphic successions to construct a high-resolution (temporal resolution of ~21.0 Kyr) regional chronostratigraphy and document species richness dynamics during the middle–late Cambrian to early Silurian interval. Our results showed that the GOBE began in the early Tremadocian and ended at the Dapingian–Darriwilian boundary and consisted of two major radiation phases. The main pulse of GOBE, which lasted from the late Floian to the earliest Darriwilian, exhibited a species richness increase with elevated origination and extinction rates. Major marine groups showed no significant diachroneity during the GOBE, with most presenting richness peaks in this event's main pulse of the GOBE. Plankton demonstrated a significant diversification from the late Cambrian to the GOBE climax and subsequently dominated the marine realm in South China. Marine life experienced two extinction events in the Late Ordovician, the Katian extinction and Hirnantian extinction, which resulted in a regional species loss of ~67%.

The Late Paleozoic Ice Age (LPIA) is a critical interval for marine ecosystems when marine fauna was viewed to have experienced a second-order mass extinction and a “sluggish” evolution with low origination and extinction rates. However, our recent study discovered that this ice age was accompanied by a rapid, significant increase of marine fauna species and genus richness. Here, we present the precise details of this biodiversification process, including the high-resolution species and genus richness changes, to decipher its timing and magnitude, as well as the divergent species richness changes of major marine clades during the event. The temporal resolutions are as high as 36 kyr and 21 kyr for the Carboniferous and Permian, respectively, and as a result provide the ability of uncovering the process in great detail. This marine biodiversification event lasted 41.2 Myr from the middle Visean of the Carboniferous to the late Asselian of the Permian with species number increased 246%, therefore named Carboniferous-earliest Permian Biodiversification Event (CPBE). CPBE includes a slow increase episode in the middle Visean to early Bashkirian and a main radiation episode of Bashkirian to Asselian. The radiation pattern is most distinct in fusulinid foraminifera while brachiopods species also kept the trend of increase. However, nektonic conodonts and cephalopods both exhibit stepwise drops during this time interval. These biotic changes might relate to the marine environmental shifts, such as suppressed marine circulation and fragmented niches, mainly raised by the Rheic Ocean closure.

The Permian–Triassic boundary (PTB) is defined by the conodont Hindeodus parvus at Meishan section D in the palaeotropical Tethyan region, where basal Triassic ammonoids are rare and poorly preserved. Here we describe some basal Early Triassic ammonoids from the lower part of the Kangshare Formation at the Qubu section in the Mt. Everest area in southern Tibet, China. Our study recognizes three distinct ammonoid zones, the Otoceras woodwardi, Ophiceras tibeticum, and Ambites zones in ascending order. The occurrence of Otoceras, a key basal Triassic taxon, is here documented for the first time in this area. The first occurrence of Triassic conodonts at Qubu indicates that the PTB is not higher than the level 0.81 m above the base of the dolomite unit of the Kangshare Formation, and the first occurrence of the ammonoid Otoceras woodwardi is 0.89 m higher up at the section. At Qubu, the Griesbachian–Dienerian boundary is placed between the Ophiceras tibeticum Zone and the Ambites Zone. Our work represents a valuable addition for the construction of a high resolution of Griesbachian and Dienerian ammonoid biozonations in southern Tibet and provides a framework for the basal Triassic correlation in the Mt. Everest area.

South China has become the most important area to establish a global stratigraphic framework of the Wuchiapingian Stage because complete Wuchiapingian sequences include the GSSPs for the base and top of the stage. As the markers of the Wuchiapingian GSSP, conodonts are the most important fossil group to establish the Wuchiapingian biostratigraphic framework. However, few documents have investigated in detail the conodont biostratigraphic succession through the entire Wuchiapingian Stage. Furthermore, the conodont taxonomy of several WuchiapingianClarkinaspecies is still debated. Therefore, we here review all WuchiapingianClarkinaspecies from South China and figure ontogenetic growth series from juvenile to adult individuals for each valid and important species in order to revise both Wuchiapingian conodont taxonomy and the biostratigraphic succession. Based on the Penglaitan, Dukou, and Nanjiang sections, seven conodont zones (Clarkina postbitteri postbitteri,C.dukouensis,C.asymmetrica,C.leveni,C.guangyuanensis,C.transcaucasica, andC.orientalis) are recognized. The WuchiapingianClarkinaspecies lineage is also reviewed to confirm the conodont biostratigraphic framework. The Guadalupian-Lopingian boundary (GLB) interval represents a sequence boundary. The time framework of the pre-Lopingian extinction interval indicates that the beginning of the end-Guadalupian regression is in the upper part of theJinogondolella postserrataZone, and the beginning of the early Lopingian transgression is in the lower part of theClarkina dukouensisZone in South China.

The “Cambrian explosion” is one of the most fascinating episodes of diversification in the history of life; however, its relationship to the oxygenation of the oceans and atmosphere around the Ediacaran–Cambrian transition is not fully understood. Marine inventories of redox-sensitive trace elements reflect the relative balance of oxidative weathering on land and deposition in anoxic water masses, and can be used to explore the evolution of oceanic and atmospheric redox conditions. For this study, we conducted a series of geochemical analyses on the upper Lantian, Piyuancun, and Hetang formations in the Chunye-1 well, part of the lower Yangtze Block in western Zhejiang. Iron speciation results indicate that the entire studied interval was deposited under anoxic conditions, with three intervals of persistent euxinia occurring in the uppermost Lantian Fm., the lower Hetang Formation (Fm.), and the upper Hetang Fm. Molybdenum (Mo) and uranium (U) contents and Mo/TOC and U/TOC ratios from the anoxic/euxinic intervals of the Chunye-1 well, combined with published data from the sections in the middle and upper Yangtze Block, suggest that the oceanic Mo reservoir declined consistently from the Ediacaran to Cambrian Stage 3, while the size of the oceanic U reservoir remained relatively constant. Both metals were depleted in the ocean in lower Cambrian Stage 4, before increasing markedly at the end of Stage 4. The lack of an apparent increase in the size of the marine Mo and U reservoir from the upper Ediacaran to Cambrian Stage 3 suggests that oxic water masses did not expand until Cambrian Stage 4. The increase in marine Mo and U availability in the upper Hetang Fm. may have been due to the expansion of oxic water masses in the oceans, associated with oxygenation of the atmosphere during Cambrian Stage 4. This expansion of oxic waters in the global ocean postdates the main phase of Cambrian diversification, suggesting that pervasive oxygenation of the ocean on a large scale was not the primary control on animal diversity following the Ediacaran–Cambrian transition.

Based on analyses of 565 conodonts from Meishan, Liangfengya, and Daijiagou (South China), and Abadeh (central Iran), we propose a revision of the seawater 87Sr/86Sr curve for the time period spanning 200 kyr prior to the Permian-Triassic boundary (PTB) to 330 kyr after the PTB. With carefully designed sample cleaning, conodonts faithfully record seawater 87Sr/86Sr. Seawater 87Sr/86Sr was 0.707030 ± 10,200 kyr prior to the PTB, rose to 0.707070 ± 10 approximately 39 kyr prior to the PTB (at the marine extinction horizon, the top of Bed 24e at Meishan), to 0.707080 ± 10 at the PTB, and to 0.707120 ± 20 at 330 kyr after the PTB. The rate of change of seawater 87Sr/86Sr was 0.0000185/Myr from the Capitanian minimum to ~ 100 kyr before the PTB, and was 0.00020 ± 7.5/Myr between ~ 100 kyr before and 330 kyr after the PTB. Over 6 Myr, this rate of change would result in a maximum 87Sr/86Sr of ~ 0.70825 at the end of the Early Triassic, compared with a model value of ~ 0.7080. The Sr data are consistent with the interpretation that the rise in marine 87Sr/86Sr was due primarily to an increase in the continental weathering and erosional flux, and that soil-binding vegetation was not re-established during most of the Early Triassic. The rapid rise in seawater 87Sr/86Sr began at least 30 kyr prior to the marine extinction at Meishan, indicating that the terrestrial extinction preceded that in the oceans.

The terrestrial Permian-Triassic transitional section at Chahe in western Guizhou Province, South China has served as a key reference section for the study of terrestrial PTB, as well as the end-Permian mass extinction on land in South China. However, Bourquin et al. (2018) recently reported that the PTB interval at Chahe has undergone serious tectonic deformation and thus is not suitable for studying the PTB transition or the terrestrial end-Permian extinction due to an unknown amount of stratigraphy removed/displaced by faulting. In order to clarify the observations of Bourquin et al. (2018), we re-surveyed the Chahe section in further detail recently and our observations suggest that the interpreted deformation by Bourquin et al. (2018) cannot be verified and it also contradicts the regional litho- and bio-stratigraphic and chemostratigraphic results. We provide detailed outcrop imagery and data for all colleagues who are interested in this section to check our observations.

Two negative carbon isotope excursions (3.5–6.5‰) across the Wuchiapingian-Changhsingian boundary (WCB) are observed globally (sections in China, Canada, and Iran); however, the causative mechanism of these excursions is debated. Here, high-resolution osmium isotope (187Os/188Os or Osi) chemostratigraphy of four globally correlated WCB sections (3 in China - Meishan, Shangsi and Lianyuan and 1 in Canada - Buchanan Lake) show two separate Osi excursions to less radiogenic compositions that are coincident with the carbon isotope shifts for two of the South China sections (Lianyuan, Meishan). In contrast, only a single Osi excursion to less radiogenic compositions, coinciding with the earliest Changhsingian carbon isotope shift, is observed for the Shangsi and Buchanan Lake sections. The Osi shift is interpreted to reflect increased unradiogenic Os input from basaltic magmatism in South China, possibly related to the Emeishan large igneous province (LIP). However, 187Os/188Os data suggest that only the earliest Changhsingian volcanism had global impact on both the ocean and atmosphere. The lack of any evidence for a biotic event associated with the WCB therefore may have been due to the more regional rather than global impact of volcanism during the latest Wuchiapingian. In contrast, during the earliest Changhsingian, volcanism was sufficient to cause a more global signal in the ocean osmium record, but was inadequate, or too prolonged, to drive any significant environmental change. Volcanism, however, may have provided the isotopically light carbon that drove the negative carbon isotope excursions across the WCB.

We present a new, biostratigraphically calibrated organic and inorganic C-isotope record spanning the basal Late Permian to earliest Triassic from southern Guizhou (Nanpanjiang basin, South China). After fluctuations of a likely diagenetic overprint are removed, three negative carbon isotope excursions (CIEs) persist. These include a short-lived CIE during the early Wuchiapingian, a protracted CIE ending shortly after the Wuchiapingian–Changhsingian Boundary, and a third CIE straddling the Permian–Triassic boundary. Comparison of our new C-isotope record with others from the same basin suggests that influences of local bathymetry and of the amount of buried terrestrial organic matter are of importance. Comparison with other coeval time series outside of South China also highlights that only the negative CIE at the Permian–Triassic boundary is a global signal. These differences can be explained by the different volumes of erupted basalts between the Late Permian Emeishan and the younger Siberian large igneous provinces and their distinct eruptive modalities. Emeishan volcanism was largely submarine, implying that sea water was an efficient buffer against atmospheric propagation of volatiles. The equatorial position of Emeishan was also an additional obstacle for volatiles to reach the stratosphere and benefit from an efficient global distribution. Consequently, the local significance of these CIEs calls into question global correlations based on C-isotope chemostratigraphy during the Late Permian. The timing of the Late Permian Chinese CIEs is also not reflected in changes in species diversity or ecology, unlike the sudden and global Permian–Triassic boundary crisis and subsequent Early Triassic upheavals.

Despite a continuous increase in fossil charcoal records from Late Palaeozoic deposits, which are used as direct evidence for palaeo-wildfires, detailed studies on the charcoal particles are still rare. To investigate the relationship between wildfire activities and the evolution of the terrestrial ecosystem at the end of the Permian, we report on the charcoal recovered from the classic non-marine Permian–Triassic Dalongkou section in Jimsar, Xinjiang Uygur Autonomous Region, Northwest China. Allochthonous and parautochthonous charcoals, identified by both macroscopic and microscopic morphological techniques, were collected from several stratigraphic horizons. These charcoals were classified into 11 categories (which do not represent the taxonomic group) according to their anatomical characteristics and gross morphology. The reflectance values of the charcoals indicate that surface fires were dominant throughout the sequence, with fire regime changing in a distinct interval. The distribution and abundance of all categories and the reflectance of the charcoals suggest that the intensity of wildfires increased in the upper part of the Guodikeng Formation. This trend coincides with the Hg/TOC peaks and a conspicuous excursion in the organic carbon isotope (δ13Corg) values, which may indicate volcanic activities and the disturbance of the carbon cycle that occurred during the Permian–Triassic transition. It is reasonable to infer that the end-Permian mass extinction (EPME) is located at the intensive wildfire interval. The reduction in spore pollen and the decrease in charcoal reflectance hint at a vegetational impoverishment that occurred after this interval. We proposed that increased wildfires, promoted by dry climate conditions and volcanism, aggravated the collapse of the forest ecosystem during the latest Permian.

The Permian Period is punctuated by Earth system changes unlike any other in geological history. The start of the Permian witnessed the termination of the Late Paleozoic Ice Age, followed by the climatic transition from icehouse to greenhouse conditions. The Guadalupian-Lopingian (Middle-Late Permian) was characterized by two biocrises associated to volcanisms: (i) the end-Guadalupian crisis and (ii) the end-Permian mass extinction. Seawater Sr isotope (87Sr/86Sr) records can shed light on the evolution of the Permian Earth system. The Permian 87Sr/86Sr record suffers from a number of issues including low resolution and potential diagenetic alteration. In this paper, we summarize the existing Permian 87Sr/86Sr records and focus on the current challenges. We also present a new, high-resolution Permian 87Sr/86Sr curve derived from pristine brachiopod shells based on data resulting from careful diagenetic screening. Our new record shows that the 87Sr/86Sr of seawater decreased continuously from the earliest Permian to the middle Capitanian (late Guadalupian), with the lowest ratio of 0.706832 registered in the Colania douvillei-Kahlerina pachiytheca Zone. Subsequently, 87Sr/86Sr ratios increased from the late Capitanian to the latest Permian and reached a ratio of 0.707167 just 0.8 m below the first occurrence of the Hindeodus parvus. We employed a stochastic oceanic box model to explore the potential drivers of the Permian seawater Sr isotope record. Our results support that changes in the hydrothermal input, rather than changes in continental weathering intensity, are the most likely controlling factor for the observed variations in Permian seawater 87Sr/86Sr. Therefore, we suggest that the marine hydrothermal system (and hence ocean basin dynamics and deep-sea temperatures) may have been the driver of the pronounced decreasing 87Sr/86Sr trend across the Permian.

The Cimmerian continent is composed of a series of blocks that were attached to the northern margin of Gondwana during the Carboniferous-Permian time, and as a consequence therefore, developed glacial sediments during the Late Paleozoic Ice Age (LPIA). These blocks rifted from Gondwana in the Early Permian, and then drifted towards the tropical area, and as a result their deposits are characterized by the mixture of warm and cool water sediments. With these previously acknowledged diagnostic features, the recognized Cimmerian blocks include Shan-Thai, Tengchong, Baoshan, Lhasa, southern Qiangtang, southern Afghanistan, and southern Iran. Carboniferous and Permian sediments and faunas in these blocks are reviewed in detail here, and disclose the most significant character of Cimmerian blocks, that is the absence of upper Carboniferous sediments, which makes them more similar to Australia and India/Pakistan, and significantly different from South China and other Tethyan regions. By the same token, central Iran, central Afghanistan, and central Pamir should be excluded from the Cimmerian blocks for distinct geological histories. The lower Carboniferous sediments present in all the Cimmerian blocks are composed of Tournaisian and Visean stages, characterized by chert nodules or lenses and oolites. Tournaisian brachiopod Syringothyris, rugose coral Cyathaxonia fauna and Siphonophyllia, and Visean bryozoan Fenestella are typical components, but overall the early Carboniferous fauna shows a Eurasian affinity. Lower Permian deposits are glacial-marine siliciclastic sequence containing cool/cold-water bivalves, small solitary non-dissepimented corals, characteristic brachiopods, low diversified but highly abundant fusulinds Pseudofusulina and Eoparafusulina, which belong to the Peri-Gondwanan fauna. The basaltic magmatism event that took place in the Cimmerian blocks was mainly in the Artinskian, which was most likely related to the initial rifting of the Cimmerian from the northern margin of Gondwana. Upper Lower Permian to Middle Permian include siliciclastics and carbonates in which cold- and warm-water mixed fauna and warm-water genera developed indicating the northward drifting of Cimmerian blocks. The marine fossils in this period are named as the Cimmerian fauna to include such characteristic taxa as the rugose coral Thomasiphyllum, fusulinids Monodiexodina and Eopolydiexodina, as well as some tropically-distributed Tethyan elements. The Upper Permian are mainly dolomitic limestones which contain the typical Cimmerian foraminifera Shanita and Hemigordius in addition to other Tethyan taxa such as the compound coral Waagenophyllum.

The middle–late Cambrian is a key interval between the Cambrian Explosion and the Great Ordovician Biodiversification Event (GOBE) that marks a major biologic evolutionary transition in the geologic record. Diversity (i.e. richness) patterns in this interval show that macro-biota experienced evolutionary setbacks for the first time. However, relatively little attention has been paid to this interval in previous macroevolutionary studies and very different conclusions about the diversity patterns in coarse time-resolution have been documented. As a dominate group of marine benthic organisms in the Cambrian, trilobites provide insightful information to understand the history of biodiversity in the Cambrian marine ecosystem from the Cambrian Explosion to the GOBE. South China is a region with relatively good preservation of Cambrian fossil materials and sections, and 4 out of 6 Cambrian GSSPs were established in South China. In this paper, we use constrained optimization (CONOP) to correlate 19 sections from South China to reduce the Signor-Lipps effect and integrate the results with high-resolution chronostratigraphic data to evaluate the middle–late Cambrian trilobite diversity pattern in South China. This study, for the first time, constructs a high time-resolution (about 60 kyr) trilobite species-level richness curve with estimated time from Age 4 to the Paibian. A double-peaked species diversification is separated by a minor extinction in Stage 4; this is followed by a gradual decline of species diversity over the entire Wuliuan Age. A radiation of three times increase of species diversity in the Drumian and Guzhangian is exhibited and the diversity remains high for most of the Guzhangian Stage; this is followed by a great extinction at the end of the Guzhangian with around 50% species lost. Detailed comparison with previous composite studies and fossil material from single sections revealed that the Signor-Lipps effect could produce large biases in diversity pattern. In addition, a precise analysis of species evolution features compared with environmental indices provides a perspective about trilobite evolutionary mechanisms associated with environmental changes related to the carbon cycle and biotic competition.

The end-Permian extinction is typically ascribed to massive volcanic eruptions, but direct geochemical evidence linking the two independent events is generally lacking. Zinc is an important micronutrient of marine phytoplanktons, and Zn isotope (δ66Zn) ratios of seawater are markedly higher than those of volcanic rocks and riverine waters. We conducted high-resolution Zn concentration and Zn isotope analyses on carbonate rocks across the Permian-Triassic boundary (PTB) in the Meishan section of south China. An abrupt increase of Zn concentration and a concomitant 0.5‰ decrease in δ66Zn occur ∼35 k.y. before the mass extinction and carbon isotope (δ13C) minima. Mass balance calculation demonstrates that a 0.5‰ negative shift in δ66Zn within thousands of years requires rapid and massive input of isotopically light Zn from volcanic ashes, hydrothermal inputs, and/or extremely fast weathering of large igneous provinces. A positive δ66Zn shift of as much as 1.0‰ following the mass extinction demonstrates that primary productivity recovered and reached a maximum in fewer than 360 k.y. Our finding provides insights into the marine Zn cycling across the PTB and clarifies the temporal relationship and duration of events, including intensive volcanism, carbon isotope excursion, mass extinction, and widespread ocean anoxia.

The Guadalupian Epoch represents one of the most critical intervals during the Earth history which is characterized by a series of global geological and biological events. However, it is poorly constrained by radioisotopic ages in comparison with the high-precision dates from the Lopingian and lowest Triassic in South China and the Cisuralian in southern Urals, Russia. In this study, we report combined CA-ID-TIMS and SIMS U-Pb zircon geochronology for three ash beds from the base and lower part of the Kuhfeng Formation in the Chaohu area, southeastern China. Zircons from Ash Beds A, C and D were initially analyzed by SIMS and yielded weighted mean 206Pb/238U dates of 269.0 ± 1.4 Ma (MSWD = 1.03, n = 31), 266.3 ± 2.2 Ma (MSWD = 2.2, n = 29) and 262.2 ± 1.7 Ma (MSWD = 1.0, n = 20) in ascending order. However, high-precion U-Pb geochronology of the same ash beds by the CA-ID-TIMS method point to important inaccuracies in the SIMS results due to Pb-loss in zircons. Ash Beds A and C yielded two TIMS weighted mean 206Pb/238U dates of 272.95 ± 0.11 Ma (MSWD = 1.9, n = 7) and 271.038 ± 0.097 Ma (MSWD = 2.2, n = 8), respectively. The depositional age of 272.95 ± 0.11 Ma for Ash Bed A is postulated as the traditional Cisuralian-Guadalupian boundary (CGB) age in South China. Our new geochronology suggests that the Guadalupian Series in South China had a total duration of 13.85 ± 0.52 myr given a Guadalupian-Lopingian boundary (GLB) age of 259.1 ± 0.5 Ma. The new age calibration of the base of the Guadalupian Series is ca. 0.65 (± 0.51) myr older than – and improves upon – the previous estimates for the CGB age and the duration of the Guadalupian Epoch based on the 2016 International Chronostratigraphic Chart (ICC) and the 2012 Geologic Time Scale (GTS).

A brachiopod fauna including 15 species belonging to 14 genera is described from a thin carbonate succession of the Lugu Formation at the Anmu section in the northern part of the South Qiangtang Block, which is about 15 km south to the Longmu Co-Shuanghu Suture. The brachiopod fauna is late Kungurian or early Guadalupian in age in terms of the presence of the brachiopod species Vediproductus punctatiformis, “Cryptospirifer” omeishanensis, and Paraplicatifera regularis. This is also generally consistent with the age indicated by the fusulines (e.g., Cancellina, Chusenella, Monodiexodina, Nankinella, Neofusulinella, Pseudofusulina, and Sphaerulina) from this formation at the nearby Mari and Duoma A (DMA) sections. Palaeobiogeographically, the brachiopod fauna exhibits a typical Cathaysian affinity and all the species are reported commonly from the equivalents in South China and Cimmerian blocks, which strongly suggest that the South Qiangtang Block had drifted to a position in the warm-water or temperate regime close to South China.

Additional specimens of rhynchonellide brachiopods from the marly limestones in the Yidade Formation at the Panxi section in eastern Yunnan have been ascribed to the species “ Paurorhyncha ” squamosa Wang, 1956 and “ P. ” depressa Wang, 1956 . The two species have been used frequently as index fossils for the Frasnian (Upper Devonian), but their taxonomic assignments are problematic because their internal structures remain unknown. In this study, detailed systematical examinations on both external characters and internal structures revealed by serial sections suggest that the two species are more appropriately assigned to the genus Hadrotatorhynchus Sartenaer, 1986 . Based on the stratigraphical distributions of Hadrotatorhynchus and the conodonts in the upper unit of the Yidade Formation, the Hadrotatorhynchus -bearing horizons are re-considered as the uppermost Givetian (Middle Devonian) rather than Frasnian stage, although the precise position of the Middle/Upper Devonian boundary still depends on further investigations of high-resolution biostratigraphy.

We investigated the kill mechanisms of the end-Permian mass extinction by analyzing patterns in biomineralization of marine invertebrates. The microstructures of Upper Permian brachiopod organocarbonate shells show the demise of the production of fabrics with a columnar layer—which has less organic matrix—in favor of more organic-rich shells at the end of Permian. Also, in the 100–120 k.y. interval prior to the Permian-Triassic boundary (PTB), the Rhynchonellata had small calcite structural units (fibers) and thus a higher shell organic content, whereas the Strophomenata were not able to produce smaller units. This suggests that the two classes had a different capacity to cope with environmental change, with the Rhynchonellata being more able to buffer against pH changes and surviving the PTB, whereas the Strophomenata became extinct. The observed trends in biomineralization are similar to the patterns in extant marine invertebrates exposed to increasing p CO 2 and decreasing pH, indicating that ocean acidification could have been one of the kill mechanisms of the mass extinction at the PTB.

The end-Permian mass extinction (EPME) was the most severe extinction event of the Phanerozoic. To investigate oceanic redox conditions around the EPME, we conducted a series of geochemical analyses, including iron speciation, trace element geochemistry, total organic carbon (TOC), and nitrogen isotopes of kerogen (δ15Nkero), around the EPME at the Shangsi section, South China. Three intervals with different redox conditions can be distinguished based on iron speciation. During the first interval (early and middle Changhsingian), bottom waters were pervasively euxinic. In the second interval (late Changhsingian and the EPME), bottom water fluctuated between oxic and anoxic, but non-sulfidic conditions, with the oxic mode becoming increasingly predominant over time. During the third interval, following the EPME, bottom waters appeared to have been consistently anoxic, although again not pervasively euxinic. This redox history is supported by enrichments in the authigenic fraction of redox-sensitive elements. These relatively high δ15Nkero values (> 1.0‰) corresponding with Changhsingian euxinia suggest reducing bottom waters did not impinge on the photic zone. The shift to values near 0‰ within and above the EPME indicates an ecological expansion of diazotrophs. Stratigraphic trends of Nixs, Cdxs, Pxs, and TOC indicate that primary productivity was highest in the first interval, coinciding with euxinic bottom water, then decreased during the lower part of Interval 2 and remained at low level through the remainder of the studied section. The temporal relationship between redox condition and primary productivity suggests that euxinia was supported by high productivity and carbon export in the early Changhsingian. The expansion of N2 fixation coincides closely with the previously documented warming of the ocean surface at Shangsi and may be related to reduced oceanic circulation and suppressed vertical mixing. The temporal distribution of deepwater anoxia and euxinia suggests that they were not primary causes for the extinction of benthos at Shangsi.

A non-fusuline foraminiferal fauna consisting of 20 genera and 27 species was documented from the middle part of the Xiala Formation at the Mujiucuo section of Xainza County, central Tibet. This fauna consists mostly of porcelaneous-walled genera such as Agathammina, Midiella, Hemigordiopsis, Neodiscus, Multidiscus , and a new genus Megacrassispirella Zhang gen. nov. These taxa indicate a Midian (Capitanian) age. The climatic amelioration, triggered by climatic warming after the Late Paleozoic Ice Age or by northern drift of the Lhasa Block, promoted diversification of the non-fusuline foraminifers in the middle part of the Xiala Formation. Warm oceanic currents also played an important role in bringing biota from low latitude areas to the northern Gondwanaland margin through the newly-formed Neotethys Ocean. One new genus, Megacrassispirella gen. nov., with Megacrassispirella xarlashanensis (Wang, 1986) emend. Zhang as type species, and one new species, Agathammina vachardi Zhang sp. nov., are described.

A high-resolution and continuous conodont apatite oxygen isotope record spanning the late Visean to Middle Permian is reported from South China, which is interpreted with respect to the ice volume and/or tropical seawater temperature history of the Late Paleozoic Ice Age (LPIA). The presented δ18O record shows significant fluctuations in δ18O from the late Visean to Middle Permian with highest values observed in the Bashkirian (Early Pennsylvanian). The δ18O maximum coincides with a major eustatic sea level fall recorded in low-latitude successions and postdates the significant increases in 87Sr/86Sr and δ13Ccarb measured on well-preserved brachiopod calcite, which can be interpreted as reflecting intensified weathering as consequence of the closure of Rheic Ocean as well as enhanced carbon burial. Both processes may have contributed to lower greenhouse gas levels and cooled down the Earth's surface, triggering the maximum glaciation. The high Bashkirian δ18O values are interpreted to represent the glacial maximum of the LPIA. A coeval change in faunal composition and a decreasing diversity in climate-sensitive marine invertebrates can be ascribed to icehouse cooling and/or loss of habitat. Despite inconsistencies with earlier interpretations that the Early Permian represented the glacial maximum of the LPIA as inferred from Gondwanan glacial sediments records, the suggested Bashkirian glacial maximum agrees well with ice extent estimates based on the regional tectonic history in Gondwana, which suggests that the Bashkirian glaciation occurred during Gondwana interior uplift promoting maximum ice cover of the entire LPIA. However, maximum glaciation is only poorly represented in the depositional record because large parts of the glacial deposits were possibly removed by erosion as outlined by a major regional unconformity.

Body size is a fundamental and defining character of an organism, and its variation in space and time is generally considered to be a function of its biology and interactions with its living environment. A great deal of body size related ecological and evolutionary research has been undertaken, mostly in relation to extant animals. Among the many body size-related hypotheses proposed and tested, the size–bathymetry relationship is probably the least studied. In this study, we compiled a global body size dataset of Changhsingian (Late Permian, ca. 254 Ma–252 Ma) brachiopod species from low-latitude areas (30°S–30°N) and analyzed their species diversity and body size distribution patterns in relation to the nearshore–offshore–basin bathymetric gradient. The dataset contained 1768 brachiopod specimens in 435 species referred to 159 genera and 9 orders, from 135 occurrences (localities) of 18 different palaeogeographic regions. Treating the whole of the Changhsingian Stage as a single time slice, we divided the nearshore–offshore–basin bathymetric gradient into three broad depth-related environments: nearshore, offshore and basinal environments, and compared how the species diversity and body size varied along this large-scale bathymetric gradient. Here, we report an array of complex patterns. First, we found a clear overall inverse correlation between species diversity and water depth along the nearshore–offshore–basin gradient, with most species concentrating in the nearshore environment. Second, when the median sizes of all low-latitude brachiopod species from the three environments were compared, we found that there was no significant size difference between the nearshore and offshore environments, suggesting that neither the wave base nor the hydrostatic pressure exerts a critical influence on the body size of brachiopods. On the other hand, the median sizes of brachiopods from the nearshore environment and, to a lesser extent, the offshore environment were found to be significantly larger than that of basinal brachiopods. This trend of significant size reduction in basinal brachiopods mirrors the relative low species diversity in the basinal environment, and neither can be easily explained by the tendency of decreasing food availability towards deeper sea environments. Rather, both trends are consistent with the hypothesis of an expanding Oxygen Minimum Zone (OMZ) in the bathyal (slope to deepsea) environments, where hypoxic to anoxic conditions are considered to have severely restricted the diversification of benthos and favored the relative proliferation of small-sized brachiopods. Finally, a significant difference was also found between eurybathic and stenobathic species in their body size response to the nearshore–offshore–basin gradient, in that eurybathic species (species found in all three environments) did not tend to change their body size significantly according to depth, whereas stenobathic forms (species restricted to a single environment) exhibit a decline in body size towards the basinal environment. This pattern is interpreted to suggest that bathymetrically more tolerant species are less sensitive to depth control with respect to their body size change dynamics, in contrast to stenobathic species which tend to grow larger in shallower water depths.

Previous studies suggest that the end-Permian mass extinction caused a dramatic drop of marine biodiversity near the Permian–Triassic boundary. However, it is unclear how profoundly this severe extinction might have changed the global provincialism, and how global provincialism responded to the protracted process of this extinction and subsequent recovery through the Triassic. In this paper, we carried out quantitative time-series analyses of global brachiopod palaeobiogeography over a timespan of nine consecutive stages/substages from the latest Permian Changhsingian to the latest Triassic Rhaetian based on a global brachiopod database of 483 genera and 2459 species from 1425 localities. Our results suggest that the extinction resulted in a global ‘biogeographical eclipse’ in the ensuing Early Triassic Griesbachian and Dienerian times in that neither biogeographic realm nor province could be recognized. It was characterized by an extreme low-diversity, mostly dwarfed and nearly globally distributed brachiopod fauna, coupled with persistently high sea surface temperature and a flattened global latitudinal thermal gradient. Global provincialization emerged again during the Olenekian at province level and reached its peak stage during the Carnian when three realms and six provinces were clearly recognized. Global provincialism became weakened again in the latest Triassic Rhaetian, marked by three general realms, but no province distinguished. Our analyses suggest that both palaeolatitude-related thermal gradient and the presence of Pangea (a profound geographic barrier) were most effective in explaining the spatial patterns. In addition, oceanic currents along the northwestern coast of Pangea also played an important (albeit regional) role in linking southern North and Central America brachiopod faunas with those of the Boreal Realm. This study also revealed that the brachiopod biodiversity center moved northwards over the studied interval, accompanied and hence accountable for by the northward drift of a large number of tectonic blocks in the Palaeotethys and Neotethys during the Triassic.

The end-Permian mass extinction reflects the most severe life crisis during the Phanerozoic and was associated with major global environmental changes. However, the consistency of the time and pattern of the terrestrial and marine extinctions remains controversial. In this paper, we presented detailed analyses of the high-resolution biostratigraphical and geochemical data from terrestrial sections in South China. Our analyses show that the transitional Kayitou Formation actually recorded the process of terrestrial mass extinction as evidenced by the mass disappearance of the Gigantopteris megaflora in the lower part, the dramatic reduction in abundance of palynomorphs in the middle, and the last occurrences of plant remains and abundant charcoal fossils in the uppermost part. It is associated with a distinct negative shift of δ13Corg, beginning in the middle part of the formation, which is correlative with that in the top of Bed 26 at the marine Meishan section. In addition, the Kayitou Formation is characterized by a distinct shift of lithofacies of fresh lake-swamp or river flat environment from olive/grey/black mudstone, siltstone, fine to coarse sandstone in the lower part to gradually increasing maroon rocks, to purely maroon mudrocks with poorly-sorted breccia, calcic palaeosols and calcareous nodules in the lowest part of the Dongchuan Formation, which indicates a dramatic collapse of soil system associated with rapid deforestation and climatic warming and drying. In the coastal area, the Kayitou Formation contains marine beds with the typical Permian–Triassic mixed faunas and floras which are correlative with the latest Changhsingian marine mixed fauna 1 at Meishan. The Kayitou Formation also recorded a distinct transgression that began in the latest Changhsingian. All above phenomena suggest that the Kayitou Formation is actually the witness of the terrestrial end-Permian mass extinction; and it is mostly or entirely of latest Changhsingian (Permian), rather than Triassic age.