Permian-Triassic Crisis Research Articles

Variability of Middle Triassic vermicular limestone ichnofabrics: the Anisian Hisban Formation in Jordan

The strongly bioturbated Middle Triassic (Anisian) limestones, referred to as vermicular limestone, are the dominant lithology of the Hisban Formation in Jordan. This limestone exhibits the monotonous Oravaichnium– Planolites ichnofabrics, which are known and common in the northern Peri-Tethys and the Germanic Basin. The most abundant and widespread trace fossil here is Oravaichnium carinatum, which is produced by bivalves. Specimens of O. carinatum from the Hisban Formation are typically strongly elongated in the vertical axis and have a smooth surface, whereas specimens from the Germanic Basin mainly have a pear-shaped cross-section. Nevertheless, both morphologies and transitional morphotypes between these ichnospecies are present in both areas. The difficulty in distinguishing between Oravaichnium and Planolites causes the intense bioturbation by bivalves to be underestimated. The wide occurrence of the Oravaichnium ichnofabric in the northern and southern Peri-Tethys suggests that small burrowing bivalves played a significant role in the colonization and infaunalization during the long-term recovery of the benthos after the Permian–Triassic crisis. They experienced intense development during the Middle Triassic, when they were responsible for extensive bioturbation.

Ostracodal evolution during the Permian–Triassic transition at the Youping section of the Nanpanjiang Basin

The Permian–Triassic mass extinction has been considered the largest bio-crisis of the Phanerozoic, with more than 90% of marine species extinct. Previous studies showed that ostracods suffered various extinction patterns in different localities and were relatively enriched in the lowermost Triassic shallow marine microbialites. Multiple hypotheses have been put forward to explore the reasons for this phenomenon. Abundant ostracod fossils were collected from the microbialite-bearing Youping section in the Nanpanjiang Basin. 45 species in 22 genera from Wujiaping Formation increased dramatically to 104 species in 33 genera from the microbialites of basal Luolou Formation. However, Ostracods from the Youping section suffered severe extinction during the second phase of the Permian–Triassic crisis, i.e., the earliest Triassic mass extinction (ETME), rather than the first phase, i.e., the latest Permian mass extinction (LPEM). In addition, the Sørenson coefficient has been used to examine the similarity of faunal associations among different sections of the Permian–Triassic transitional beds. There was no significant differences for ostracods between microbialites and non-microbialites sections based on similarity analysis. Thus, we proposed that “Shallow marine refuge” hypothesis could explain the high diversity and high abundance of ostracods of the Permian–Triassic transitional beds. Besides, ostracods showed remarkable geographical differentiation at both regional and global scales during the Permian–Triassic transitional beds and were presumably controlled by geographical isolation.

A new Early Triassic brachiopod fauna from southern Tibet, China: Implications on brachiopod recovery and the late Smithian extinction in southern Tethys

AbstractBrachiopods suffered high levels of extinction during the Permian–Triassic crisis, and their diversity failed to return to Permian levels. In the aftermath of the Permian-Triassic mass extinction, brachiopods were extremely rare worldwide, especially in the southern hemisphere. Here, we report a new Early Triassic brachiopod fauna from the Selong section in southern Tibet, China. A new genus and three new species have been identified: Selongthyris plana Wang and Chen n. gen. n. sp., Piarorhynchella selongensis Wang and Chen n. sp., and Schwagerispira cheni Wang and Chen n. sp., which are typical. The ontogenies and internal structures of these three new species are described in detail. This brachiopod fauna corresponds to the Neospathodus pakistanensis and Neospathodus waageni conodont biozones and Kashmirites and Anasibirites ammonoid biozones, indicating a late Dienerian to late Smithian age. The post-extinction recovery of brachiopods in the Himalayas may have begun by the early Smithian of the Early Triassic. In addition, these species did not persist into the Spathian substage, suggesting that the newly evolved brachiopods in the southern Tethys were severely affected by the late Smithian extinction event.UUID: http://zoobank.org/f8fc8ced-432c-41d2-8c6c-d17bca527109

Palaeoecological Implications of Lower-Middle Triassic Stromatolites and Microbe-Metazoan Build-Ups in the Germanic Basin: Insights into the Aftermath of the Permian–Triassic Crisis

Following the end-Permian crisis, microbialites were ubiquitous worldwide. For instance, Triassic deposits in the Germanic Basin provide a rich record of stromatolites as well as of microbe-metazoan build-ups with nonspicular demosponges. Despite their palaeoecological significance, however, all of these microbialites have only rarely been studied. This study aims to fill this gap by examining and comparing microbialites from the Upper Buntsandstein (Olenekian, Lower Triassic) and the lower Middle Muschelkalk (Anisian, Middle Triassic) in Germany. By combining analytical petrography (optical microscopy, micro X-ray fluorescence, and Raman spectroscopy) and geochemistry (δ13Ccarb, δ18Ocarb), we show that all the studied microbialites formed in slightly evaporitic environments. Olenekian deposits in the Jena area and Anisian strata at Werbach contain stromatolites. Anisian successions at Hardheim, in contrast, host microbe-metazoan build-ups. Thus, the key difference is the absence or presence of nonspicular demosponges in microbialites. It is plausible that microbes and nonspicular demosponges had a mutualistic relationship, and it is tempting to speculate that the investigated microbial-metazoan build-ups reflect an ancient evolutionary and ecological association. The widespread occurrence of microbialites (e.g., stromatolites/microbe-metazoan build-ups) after the catastrophe may have resulted from suppressed ecological competition and the presence of vacant ecological niches. The distribution of stromatolites and/or microbe-metazoan build-ups might have been controlled by subtle differences in salinity and water depth, the latter influencing hydrodynamic processes and nutrient supply down to the microscale. To obtain a more complete picture of the distribution of such build-ups in the earth’s history, more fossil records need to be (re)investigated. For the time being, environmental and taphonomic studies of modern nonspicular demosponges are urgently required.

Latentifistularia and other radiolarian species from the lower Smithian (Lower Triassic) Lang Son Formation, NE Vietnam

Well-preserved Early Triassic radiolarians were recovered from lower Smithian (lower Olenekian) beds in NE Vietnam. The radiolarian assemblage consists only of Paleozoic relict species of Latentifistularia and some entactinarians. Three latentifistularian species, Ruzhencevispongus vietnamensis nov. sp., Tetragregnon chilangensis nov. sp., and Tetragregnon langsonensis nov. sp., belonging to the families Ruzhencevispongidae Kozur and Tetratormentidae Nestell and Nestell are erected herein. The entactinarian family Triassothamnidae nov. fam. and one new genus and two new species of Langsonsphaera pseudocubica nov. gen. nov. sp. and Stigmosphaerostylus amabilis nov. sp. are also described. In this region, the Paleozoic-type radiolarian groups Latentifistularia and Entactinaria survived across the Permian–Triassic boundary and were present during the Induan–early Olenekian interval. Thus, in the eastern Tethyan seaway near the equator, the true extinction of some Paleozoic radiolarian groups took place at the middle of the Early Triassic, immediately after the Smithian, rather than during the Permian–Triassic crisis.

Morphophysiological Peculiarities of Articulated Brachiopods and Marine Bryozoans as a Reason for Their Different Evolutionary Consequences of the Permian–Triassic Crisis

Morphophysiological Peculiarities of Articulated Brachiopods and Marine Bryozoans as a Reason for Their Different Evolutionary Consequences of the Permian–Triassic Crisis

Late Anisian microbe‐metazoan build‐ups in the Germanic Basin: aftermath of the Permian–Triassic crisis

The so-called Permian–Triassic mass extinction was followed by a prolonged period of ecological recovery that lasted until the Middle Triassic. Triassic stromatolites from the Germanic Basin seem to be an important part of the puzzle but have barely been investigated so far. Here, we analysed late Anisian (upper Middle Muschelkalk) stromatolites from across the Germanic Basin by combining petrographic approaches (optical microscopy, micro X-ray fluorescence, Raman imaging) and geochemical analyses (sedimentary hydrocarbons, stable carbon and oxygen isotopes). Palaeontological and sedimentological evidence, such as Placunopsis bivalves, intraclasts and disrupted laminated fabrics, indicate that the stromatolites formed in subtidal, shallow marine settings. This interpretation is consistent with δ13Ccarb of about −2.1‰ to −0.4‰. Occurrences of calcite pseudomorphs after gypsum possibly suggest occasionally elevated salinities, which is well in line with the relative rarity of fossils in the host strata. Remarkably, the stromatolites are composed of microbes (perhaps cyanobacteria and sulphate-reducing bacteria) and metazoans such as non-spicular demosponges, Placunopsis bivalves and/or microconchids. Therefore, these ‘stromatolites’ should more correctly be referred to as microbe-metazoan build-ups. They are characterized by diverse lamination types, including planar, wavy, domal and conical ones. Microbial mats likely played an important role in forming the planar and wavy laminations. Domal and conical laminations commonly show clotted to peloidal features and mesh-like fabrics, attributed to fossilized non-spicular demosponges. Our observations not only point up that non-spicular demosponges are easily overlooked and might be mistakenly interpreted as stromatolites, but also demonstrate that microbe-metazoan build-ups were widespread in the Germanic Basin during Early to Middle Triassic times. In the light of our findings, it appears plausible that the involved organisms benefited from elevated salinities. Another (not necessarily contradictory) possibility is that the mutualistic relationship between microbes and non-spicular demosponges enabled these organisms to fill ecological niches cleared by the Permian–Triassic crisis. If that is to be the case, it means that such microbe-metazoan associations maintained their advantage until the Middle Triassic.

Morphological selectivity of the Permian-Triassic ammonoid mass extinction

Abstract Ammonoids suffered a diversity bottleneck during the Permian-Triassic mass extinction (PTME) and experienced a rapid diversification in the Early Triassic. However, the kinds of ammonoids that were more likely to survive the PTME and that fueled subsequent diversification are still poorly known. We compiled a comprehensive morphological data set and used the nonmetric multidimensional scaling method to reveal the impact of the PTME on the morphological selectivity of ammonoids. Our results show that postextinction taxa occupied a quite different morphospace when compared with the pre-extinction assemblages. The survivors were mainly smooth and weakly ornamented forms, while the late Permian species were dominated by coarsely ornamented forms. Contrary to previously recognized nonselective patterns, these results suggest a morphological selectivity of the Permian-Triassic crisis. Newcomers in the Griesbachian were mainly compressed and smooth forms. This morphological shift from the coarsely ornamented ammonoids dominating the Changhsingian to the smooth ammonoids dominating the Griesbachian possibly suggests an ecological turnover of ammonoids during the PTME.

Two distinct episodes of marine anoxia during the Permian-Triassic crisis evidenced by uranium isotopes in marine dolostones

The end-Permian mass extinction (EPME; ca. 251.94 Ma) is the most severe mass extinction in the geological record. Detailed paleobiological investigations show a very rapid EPME event, and recently published δ238U data show a large negative excursion and thus a massive shift to globally expanded anoxia at the main extinction phase in the latest Permian. The negative shift in δ238U is in correlation with a globally characterized negative δ13C excursion near the Permian-Triassic boundary (PTB). In some highly expanded PTB carbonate sections, however, there are two distinct negative δ13C excursions whereas uranium isotopes (δ238U) from such sections have not yet been examined, leaving a gap in the understanding of the global perturbations of marine redox conditions immediately following the EPME. Here, we present a new δ238U study of syn-depositional dolostones from a well-characterized and highly expanded drill core, which recorded two pronounced negative δ13C excursions across the PTB, from the Carnic Alps, Austria. This drill core extends 331-meters across the PTB and provides a unique opportunity to explore the detailed timing, duration, and extent of marine redox chemistry changes before, during, and immediately after the EPME. Our new δ238U record shows two negative shifts, which are correlated with the two negative δ13C excursions. The first negative δ238U excursion preceding the EPME confirms the recently published δ238U records from across the EPME and support that syndepositional marine dolostones can record δ238U trends of seawater similar to that of limestones. Modeling of uranium isotope cycling in the latest Permian and earliest Triassic oceans suggests two distinct stages of expanded marine anoxia separated by a brief interval (∼100 kyr) of reoxygenation across the PTB. The first anoxic episode lasted for ∼ 60 kyr while anoxic seafloor area expanded to cover >18% of the entire seafloor, coeval with the main EPME horizon, agreeing with marine anoxia as a proximate kill mechanism for the EPME. The second anoxic event was less intense compared to the first anoxic pulse but sustained for a longer duration. A global modeling of coupled C, P, and U cycles show that two pulses of volcanic carbon injection that drives global warming and increased phosphorus weathering rate can reasonably reproduce our data to match two phases of anoxia. The model also demonstrates that the loss of terrestrial vegetation in the EPME is crucial to generating an intervening interval of oxygenated ocean. Our new study adds to a growing body of evidence that the global marine redox conditions underwent rapid oscillations during the EPME event and continued afterward, which may have played a central role in delaying the marine ecosystem recovery in the Early Triassic.

A glance at the deep past history of insects

A glance at the deep past history of insects

Palaeoenvironments, flora, and organic carbon and nitrogen isotope changes across the non-marine Permian-Triassic boundary at Wybung Head, Australia

The Permian-Triassic boundary section at Wybung Head, eastern Australia shows a rapid change from humid coal-bearing lowland braided stream through a thin clay and coal breccia and paleosols to semi-arid silty floodplain deposits. Identifiable plant remains and total organic matter disappear above the coal and clay breccia. Three characteristic palynofacies accumulated in a range from oxic to sub-oxic to anoxic conditions. The dominance of opaque phytoclasts in the entire sequence reflects deposition under oxic conditions, especially in the sequence lying above the Birdie Coal, the result of fluctuating water tables, high energy and desiccating conditions. In the Birdie Coal, however, at certain horizons, a water-saturated environment favored the preservation of organic matter such as pollen, spores, and structured organic matter. This latest Permian paleovegetation was dominated by opportunistic understory spore-bearing plants, with a canopy of pollen-bearing glossopterids, conifers and cordaitales. Total organic carbon drops from >30% in the coal, through <5% in the breccia to <1% in the paleosols and silts. The organic δ13C values are constant at ~ −25.5‰ in the coal and coal breccia, but then decrease to less than −27‰ in the paleosols and silts. These results confirm the rapid sedimentary, floral and organic carbon isotope changes across the non-marine Permian-Triassic boundary in eastern Australia. Our δ13Corg values suggest a significant and sustained negative δ13Corg excursion, with a magnitude of about 3‰, above the Birdie Coal. Unlike δ13Corg, there is no clear trend in δ15Norg values. The low C/N ratios of 10 and less, of the samples above +55 cm, are only found in modern burned soils with low bacteria/fungi ratios or in decaying wood. There is no obvious fungal spike in the Wybung Head section, may have been destroyed during the formation of this soil B horizon, as elsewhere a global fungal spike layer marks an interval of decreased terrestrial biomass and decaying vegetation associated with the Permian-Triassic crisis and boundary. Two negative excursions in the uppermost Permian and lowest Triassic can be correlated throughout Gondwana.

Facies and evolution of the carbonate factory during the Permian–Triassic crisis in South Tibet, China

AbstractThe nature of Phanerozoic carbonate factories is strongly controlled by the composition of carbonate‐producing faunas. During the Permian–Triassic mass extinction interval there was a major change in tropical shallow platform facies: Upper Permian bioclastic limestones are characterized by benthic communities with significant richness, for example, calcareous algae, fusulinids, brachiopods, corals, molluscs and sponges, while lowermost Triassic carbonates shift to dolomicrite‐dominated and bacteria‐dominated microbialites in the immediate aftermath of the Permian–Triassic mass extinction. However, the spatial–temporal pattern of carbonates distribution in high latitude regions in response to the Permian–Triassic mass extinction has received little attention. Facies and evolutionary patterns of a carbonate factory from the northern margin of peri‐Gondwana (palaeolatitude ca 40°S) are presented here based on four Permian–Triassic boundary sections that span proximal, inner to distal, and outer ramp settings from South Tibet. The results show that a cool‐water bryozoan‐dominated and echinoderm‐dominated carbonate ramp developed in the Late Permian in South Tibet. This was replaced abruptly, immediately after the Permian–Triassic mass extinction, by a benthic automicrite factory with minor amounts of calcifying metazoans developed in an inner/middle ramp setting, accompanied by transient subaerial exposure. Subsequently, an extensive homoclinal carbonate ramp developed in South Tibet in the Early Triassic, which mainly consists of homogenous dolomitic lime mudstone/wackestone that lacks evidence of metazoan frame‐builders. The sudden transition from a cool‐water, heterozoan dominated carbonate ramp to a warm‐water, metazoan‐free, homoclinal carbonate ramp following the Permian–Triassic mass extinction was the result of the combination of the loss of metazoan reef/mound builders, rapid sea‐level changes across Permian–Triassic mass extinction and profound global warming during the Early Triassic.

Carbonate thermoluminescence and its implication for marine productivity change during the Permian-Triassic transition

The Permian-Triassic (P-Tr) crisis was the largest mass extinction of the Phanerozoic and eliminated over 90% of marine species. However, the nature of marine productivity changes during the crisis is a matter of on-going debate. Here, thermoluminescence (TL) measurements from 144 bulk carbonate samples from Meishan (South China) show two levels of variation in TL peak intensities at ~270 °C. The first-order variation is characterized by a rapid, nearly three-fold increase. A secondary variation is interpreted to record periodic fluctuations on a Milankovitch scale (~20-kyr rhythm). The periodic variations of TL are negatively correlated with Mn concentrations, suggesting primary productivity is a key factor controlling the TL peak intensity by photo-reduction of particulate Mn in the presence of organic matter. Therefore, the periodic fluctuations of TL were likely controlled by primary productivity changes on orbital timescales. A significant rise of TL peak intensities across the P-Tr boundary represents the rapid increase of dissolved Mn associated with enhanced marine productivity and/or oceanic anoxia.

New Stage of Recovery of East European Tetrapod Community after Permian–Triassic Crisis

New data on the taxonomic composition and comparison of the tetrapod assemblage from the Upper Sukhorechenskaya Subformation of the Buzuluk Depression of the East European Platform, previously described as “Selenocara–Syrtosuchus fauna,” are provided. This assemblage is dated Late Induan (Dienerian) and characterizes a new stage in recovery of East European tetrapod community after the Late Permian extinction, which is intermediate between the Tupilakosaurus and Benthosuchus faunas. Beyond Eastern Europe, a similar amphibian association is known from the Anodontophora fassaensis Zone (upper part of the Wordie Creek Formation) of eastern Greenland.

Global and regional variations in tropical marine environments of Gondwana as revealed by a multi-stable isotope study, Middle Triassic (Anisian), Israel, Levant Basin

The world during the early Middle Triassic (Anisian) was characterized by a distinct recovery of the carbonate factory after the Permian–Triassic crisis. This recovery seems to have passed over the Anisian environment on the tropical northern margin of Gondwana (Israel, Levant Basin) and to have resulted in the low diversity of barren horizons of carbonate-secreting organisms. Four Anisian successions (the Ramon 1, Hameishar 1, Nafha 1, and David 1 boreholes) were studied to decode the factors preventing regional recovery. A multi-proxy analysis was performed on these boreholes, including the carbonate/siliciclastic ratio, total organic carbon (TOC), carbon/nitrogen (C/N) ratio and inorganic carbon (δ13Ccarb), oxygen (δ18Ocarb), and nitrogen (δ15N) isotopic compositions. The aim of assessing the combination of these proxies was to characterize the geochemical conditions in the regional basins. These successions record two C-cycle perturbation events, characterized by negative shifts in δ13Ccarb values and recognized in most successions, indicating the land-marine teleconnection effect on the C-cycle perturbation. The δ18Ocarb excursions revealed similar oscillation trends, with global warming evidenced by increasing circumtropical precipitation and terrestrial influxes, whereas global cooling was reflected by increased carbonate factory production. The low δ15N values in all of the studied successions indicated the presence and flourishing of N-fixers. The absence or scarcity of carbonate-secreting organisms suggests that these N-fixers were the source of the carbonate fraction in the sediments. Episodic events with high δ15N values suggest an accumulation of terrestrial organic matter (OM) or oxygenation events, allowing short-term colonization by benthic fauna at the marine sites.

Rapid biotic rebound during the late Griesbachian indicates heterogeneous recovery patterns after the Permian-Triassic mass extinction

New fossil data from two Early Triassic (Griesbachian to Dienerian) sections from South China show unusually high levels of both benthic and nektonic taxonomic richness occurring in the late Griesbachian. In total, 68 species (including 26 newly originated species) representing mollusks, brachiopods, foraminifers, conodonts, ostracods, and echinoderms occur in the late Griesbachian, indicating well-established and relatively complex marine communities. Furthermore, the nekton shows higher origination rates than the benthos. Analyses of the sedimentary facies and size distribution of pyrite framboids show that this high-diversity interval is associated with well-oxygenated environments. In contrast to the previously suggested scenario, which inferred that persistently harsh environmental conditions impeded the biotic recovery during the Early Triassic, our new findings, combined with recent work, indicate a fitful regional recovery pattern after the Permian-Triassic crisis, resulting in three main diversity highs: late Griesbachian–early Dienerian, early–middle Smithian, and Spathian. The transient rebound episodes were therefore influenced by both extrinsic local (e.g., redox condition, temperature) and intrinsic (e.g., biological tolerances, origination rates) parameters.

Cadmium isotopic evidence for the evolution of marine primary productivity and the biological extinction event during the Permian-Triassic crisis from the Meishan section, South China

Abstract Cadmium (Cd) isotopic compositions in seawater are important parameters for tracing the biogeochemical cycling of Cd in modern oceans and may be used as a direct proxy for nutrient utilization by phytoplankton and an indirect proxy for primary productivity. In this study, we measured the stable Cd isotope ratios (δ114Cd) of marine sedimentary carbonates from the Meishan section in Changxing County of Zhejiang Province, South China, the Global Stratotype Section and Point (GSSP) of the Permian-Triassic Boundary (PTB). The results suggest that the inferred marine primary productivity recorded in the marine carbonates from the Late Permian (i.e., before the mass extinction) was high and relatively stable (the δ114/110Cd values of carbonates range from +0.31‰ to +0.60‰; after correction for salinity-controlled fractionation into inorganic calcite, the δ114/110Cd values of palaeo-seawater range from +0.47‰ to +0.79‰). During the mass extinctions, the δ114/110Cd values of carbonates abruptly decreased at the beginning of each episode of mass extinction, suggesting that the primary productivity of the palaeo-ocean declined before each episode of extinction events at the PTB. We suggest that the mass extinction events at the PTB in the Meishan section could be a ripple effect due to the destruction of primary producers at the base of the food chain in the palaeo-ocean ecosystem.

A new stem group echinoid from the Triassic of China leads to a revised macroevolutionary history of echinoids during the end-Permian mass extinction.

The Permian–Triassic bottleneck has long been thought to have drastically altered the course of echinoid evolution, with the extinction of the entire echinoid stem group having taken place during the end-Permian mass extinction. The Early Triassic fossil record of echinoids is, however, sparse, and new fossils are paving the way for a revised interpretation of the evolutionary history of echinoids during the Permian–Triassic crisis and Early Mesozoic. A new species of echinoid, Yunnanechinus luopingensis n. sp. recovered from the Middle Triassic (Anisian) Luoping Biota fossil Lagerstätte of South China, displays morphologies that are not characteristic of the echinoid crown group. We have used phylogenetic analyses to further demonstrate that Yunnanechinus is not a member of the echinoid crown group. Thus a clade of stem group echinoids survived into the Middle Triassic, enduring the global crisis that characterized the end-Permian and Early Triassic. Therefore, stem group echinoids did not go extinct during the Palaeozoic, as previously thought, and appear to have coexisted with the echinoid crown group for at least 23 million years. Stem group echinoids thus exhibited the Lazarus effect during the latest Permian and Early Triassic, while crown group echinoids did not.

A new Dienerian (Early Triassic) brachiopod fauna from South China and implications for biotic recovery after the Permian–Triassic extinction

AbstractBrachiopods suffered severe extinction during the Permian–Triassic crisis, such that their diversity dropped to extremely low levels in the Early Triassic. Here we describe a new brachiopod fauna from the Dienerian of Lichuan, South China. This fauna consists of three monospecific genera, including one new genus and one new species: Lichuanorelloides lichuanensis gen. et sp. nov., Lissorhynchia sp. and Crurithyris sp. These brachiopods co‐occur with the ammonoids Ussuridiscus, Jieshaniceras, Hubeitoceras and Vishnuites, suggesting an early Dienerian age. The geographical distribution of brachiopods in family Norellidae during the Early Triassic suggests that a migration took place towards higher latitudes, which may have been caused by the extreme climate warming that prevailed during the Dienerian.

Body-size changes of latest Permian brachiopods in varied palaeogeographic settings in South China and implications for controls on animal miniaturization in a highly stressed marine ecosystem

Research on the dynamics of body-size changes in varied water depths can provide important insights into the evolution of palaeoenvironments through time. This paper attempts to investigate how the body sizes of two most commonly found chonetid brachiopod species in the uppermost Permian in South China varied with palaeo-bathymetry. The result shows that there is a broadly negative correlation between the latest Permian brachiopod body size and water depth. There is no simple singular variable that could explain this correlation because bathymetry is correlated, either linearly or nonlinearly, to food availability, redox condition and habitat temperature, as well as substrate conditions. Overall, we found that both oxygen and food availability played a more important role in controlling the differences of body sizes, and specifically several depressed factors (low food availability, anoxia, or abnormal temperature) have compounded and caused small body sizes in deeper waters during the latest Permian. We propose that the brachiopod miniaturization during the Permian-Triassic crisis in South China was collectively driven by anoxia, food restriction and high temperature.