Mass Extinction Research Articles

Surviving the Tide: Assessing Guiana dolphin persistence amidst growing threats in a protected estuary in South-eastern Brazil

This study investigated the population viability of Sotalia guianensis in the Cananéia Estuarine-Lagoon Complex, considering current and potential future scenarios. Simulations, using VORTEX software v. 10.5.5.0, spanned 100 years and were iterated 1000 times. Scenarios encompassed adjustments to demographic and environmental factors, evaluating population trajectories (baseline; increase fisheries; increase tourism; and increase harbour activity scenarios). Findings revealed a potential stochastic growth rate and population stabilization in baseline and increase tourism scenarios when major threats were absent. Conversely, increase fishing and harbour activity scenarios exhibited population decline, leading to eventual extinction within 100 years. Projected growth rates for all Scenarios were 0.0298 (SD=0.0424), −0.2650 (SD=0.2825), 0.0294 (SD=0.0654), and −0.0334 (SD=0.1145) respectively, with extinction probabilities of 0.0 for baseline and increase tourism scenarios, 1.0 for increase fishing scenario with mean estimated extinction time at 14 years, and 0.4430 for increase harbour activity scenario with mean estimated extinction time at 80.1 years. Sensitivity testing identified the percentage of adult females breeding and female mortality as the parameters most significantly impacting population trends. The simulations provided important insights into the primary factors impacting the viability of Sotalia guianensis and lay the groundwork for future population assessments and conservation plans.

Young Children Moving through Ecological Anxiety and Grief: Dancing with Demolition

ABSTRACT As the extent of planetary unraveling becomes increasingly apparent, scholars are beginning to document responses to the loss of ecological systems, mass extinctions, and climate change. However, there are few studies documenting children’s eco-anxiety responses. In this study, children’s eco-anxiety and grief became apparent when they expressed dismay at the imminent demolition of a derelict building. Children were concerned for the fate of the building, the land on which it stood, and the myriad others it sheltered. Using participatory and creative methodologies including dance, this project worked with children to tell a more-than-human story of becoming-with children-building-weeds-graffiti-dust-researchers-unhoused-bacteria-rats-and unloved others, which culminated in a video work. In this article Butler’s concept of “grievability” is extended to include those not typically thought to be “grievable.” The article concludes with a discussion about how dance improvisation allowed children to express feelings of loss and move through their eco-anxiety and grief.

Molecular Innovations Shaping Beak Morphology in Birds.

The beak, a pivotal evolutionary trait characterized by high morphological diversity and plasticity, has enabled birds to survive mass extinction events and subsequently radiate into diverse ecological niches worldwide. This remarkable ecological adaptability underscores the importance of uncovering the molecular mechanisms shaping avian beak morphology, particularly benefiting from the rapidly advancing archives of genomics and epigenomics. We review the latest advancements in understanding how genetic and epigenetic innovations control or regulate beak development and drive beak morphological adaptation and diversification over the past two decades. We conclude with several recommendations for future endeavors, expanding to more bird lineages, with a focus on beak shape and the lower beak, and conducting functional experiments. By directing research efforts toward these aspects and integrating advanced omics techniques, the complex molecular mechanisms involved in avian beak evolution and morphogenesis will be deeply interpreted.

Coral Moroccan biodiversity after the End-Triassic mass extinction

Each new coral-bearing outcrop found in Lower Jurassic strata is useful to understand the evolution of corals between the end-Triassic mass extinction and the Toarcian anoxic event. Here we provide new taxonomic data on corals issued from fieldwork on four outcrops from the region of Amellagou, in the High Atlas Mountains, Morocco. A set of 157 coral specimens have been collected from a small biostrome, a giant reef and two olistholiths, spanning from Hettangian – Sinemurian time interval to Early Pliensbachian. These corals are distributed in 14 families, 22 genera and 27 species. Among these species, two are new: Lepidophyllia (Heterastraea) microcalix sp. nov., represented enough to allow a population study and Paracuifia castellum sp. nov. The study extends the last appearance datum of several genera known only in the Triassic till now, namely: Parastraeomorpha, Araiophyllum, Paracuifia, Pinacophyllum and, possibly, Paravolzeia. For this reason, the severity of the end-Triassic mass extinction is questioned in comparison to the extinction events that happened around the Pliensbachian-Toarcian boundary. For this reason, moreover, the phyletic discontinuity between some Triassic and Jurassic taxa is also addressed. Some Lazarus taxa known from Triassic and Pliensbachian remain absent in Hettangian and now, at a lesser degree, in Sinemurian. That is why we assume that the absence of these taxa is only due to the poor preservation of coral environments during these times. This study also changes our view on the first appearance datum of several genera that were known in Jurassic strata, namely: Proleptophyllia, Vallimeandropsis and, possibly, Lochmaeosmilia. A special attention is given to the distribution of colonial arrangements and points to the important proportion of cerioid and solitary corals. Additionally, the study highlights the existence of significant proportions of thamnasterioid and meandroid forms. The presence of corals with such a level of integration, together with the occurrence of two species that show platy to ramose transition in their colony shape, namely Hispaniastraea murciana and Chrondrocoenia clavellata, stresses the effectiveness of a photosymbiosis in these Early Jurassic coral communities. Lastly, the proportion of solitary specimens increased over time, revealing the uniqueness of coral assemblages during the Pliensbachian.

Reintroduction of resistant frogs facilitates landscape-scale recovery in the presence of a lethal fungal disease.

Vast alteration of the biosphere by humans is causing a sixth mass extinction, driven in part by an increase in infectious diseases. The emergence of the lethal fungal pathogen Batrachochytrium dendrobatidis (Bd) has devastated global amphibian biodiversity. Given the lack of any broadly applicable methods to reverse these impacts, the future of many amphibians appears grim. The Sierra Nevada yellow-legged frog (Rana sierrae) is highly susceptible to Bd infection and most R. sierrae populations are extirpated following disease outbreaks. However, some populations persist and eventually recover, and frogs in these recovering populations have increased resistance against infection. Here, we conduct a 15-year reintroduction study and show that frogs collected from recovering populations and reintroduced to vacant habitats can reestablish populations despite the presence of Bd. In addition, the likelihood of establishment is influenced by site, cohort, and frog attributes. Results from viability modeling suggest that many reintroduced populations have a low probability of extinction over 50 years. These results provide a rare example of how reintroduction of resistant individuals can allow the landscape-scale recovery of disease-impacted species, and have broad implications for amphibians and other taxa that are threatened with extinction by novel pathogens.

Insights into the K–Pg extinction aftermath: The Danish Cerithium Limestone Member

The Cretaceous–Palaeogene (K–Pg) mass extinction about 66 Ma ago was one of Earth's largest mass extinction events. The demise of calcifiers, among others, influenced biogeochemical cycles and changed the conditions for carbonate deposition in the global ocean. This study addresses the sedimentology and carbonate microfacies of the Cerithium Limestone Member of the Rødvig Formation within the renowned Stevns Klint succession in Denmark. The limestone was deposited in the earliest Danian Stage, immediately after the K–Pg mass extinction. It is a pale yellow, partly cemented unit with a dense network of Thalassinoides burrows and numerous flint nodules. Studies of the thin sections revealed that the Cerithium Limestone Member is more variable than expected from its overall homogeneous appearance at the macroscopic scale. The thin sections and scanning electron microscope (SEM) images showed that the highly bioturbated limestone consists of four principal microfacies: a mudstone, a wackestone and two different packstones. The 30 to 120-cm thick Cerithium Limestone Member fills depressions between low-amplitude mounds in the Maastrichtian chalk. The lowermost part constitutes a thin layer of a bryozoan-rich packstone, probably reworked from the crests of the Maastrichtian mounds. The successive part of the member is dominated by wacke stone with mainly foraminifera (planktic and benthic), molluscs and echinoderm debris, and in some areas an abundance of peloids. The foraminifera- and mollusc rich packstone appears in lenses. The mudstone contains few foraminifera and is linked to burrows and syn-sedimentary fractures. SEM observations revealed that the Cerithium Limestone Member corresponds to a dispersed micrite, with small calcite crystals ~1–4 µm in size. The general shape of these calcite crystals suggests precipitation from cyanobacterial activity and, thus, a microbial genesis for the micrite of the Cerithium Limestone Member.

Calibrations without raw data—A response to “Seasonal calibration of the end-cretaceous Chicxulub impact event”

A recent article by DePalma et al. reported that the season of the End-Cretaceous mass extinction was confined to spring/summer on the basis of stable isotope analyses and supplementary observations. An independent study that was concurrently under review reached a similar conclusion using osteohistology and stable isotope analyses. We identified anomalies surrounding the stable isotope analyses reported by DePalma et al. Primary data are not provided, the laboratory where the analyses were performed is not identified, and the methods are insufficiently specified to enable accurate replication. Furthermore, isotopic graphs for carbon and oxygen contain irregularities such as missing data points, duplicate data points, and identical-length error bars for both elements despite different scales, that appear inconsistent with laboratory instrument outputs. A close examination of such methodological omissions and data irregularities can help to raise the standards for future studies of seasonality and prevent inaccurate claims or confirmation bias.

Why some ‘inbreeder’ species among mostly outbreeders? conifer examples, a postulate, and research agenda

AbstractBreeding systems vary widely in plants, but mostly cluster towards outbreeding or inbreeding extremes. Conifers, which are woody and generally long-lived perennials, are almost all classical outbreeders, but include occasional species characterised as inbreeders. The latter include some very narrow endemics, but narrow endemics include outbreeders. The inbreeders show high self-fertility, minimal inbreeding depression, typically low DNA polymorphism, and modest functional genetic variation, but self-fertilisation rates can be low. Seven such species are reviewed. It is widely (if often tacitly) assumed that inbreeders arise through severe population bottlenecks. It is proposed, more specifically, that inbreeders could arise through recessive resistance alleles of large effects being expressed, during biotic crises, through some inbreeding in the typically mixed mating systems of outbreeders. Such a crisis might produce not only a population bottleneck but also the conditions for recessive alleles to operate beneficially to make inbreeding advantageous. Avenues for probing the recessive-alleles hypothesis are: quantitative modelling to identify what are plausible conditions, examining genomic signatures of inbreeders, and empirical observation. Appropriate modelling appears challenging, as does seeking informative genomic signatures. Empirical observation, however, may be facilitated by biotic crises promoted by current global migration of pathogens and animal pests.

Exploring the Role of Tools and Technologies in Enhancing Human Knowledge Acquisition: The Flora of Cambodia as a Pilot Project.

The globalization of the world profoundly impacts the academic and scientific domains. Technological advances have enabled an immeasurable progress in many scientific fields, for example structural or functional genomics, bioinformatics or even the development of artificial intelligence, which is becoming a catalyst for disciplines such as taxonomy. However, we are witnessing an unprecedented paradox. We have entered a period described as the 6th mass extinction (e.g., Ceballos et al. 2015, Ceballos et al. 2020, Cowie et al. 2022), where biodiversity has been in decline for many years because of anthropogenic activity (Myers et al. 2000, Sachs et al. 2009, Butchart et al. 2010) and yet, techniques have never been so advanced (e.g., online databases, metabarcording and eDNA identification methods). They produce a deluge of results and data that must be managed to facilitate their access and re-use and benefit to all users, i.e., scientists and stake-holders or policy makers on a global scale. Currently, the flora of Cambodia is part of the Flora of Cambodia, Laos and Viêt-nam*1 and is jointly edited by the Royal Botanic Garden of Edinburgh and the Muséum national d’Histoire naturelle in Paris since 2013. Given Cambodia's historical ties to French Indochina, France's long-term presence has significantly contributed to the documentation of Cambodia's biodiversity. The largest collection of Cambodian specimens is housed at the Paris Herbarium. The Flora of Cambodia project (Ung 2023) started in 2023 as a pilot project for testing the effectiveness of different open tools developped for taxonomists, e.g., the echinopscis platform*2 developped at the Royal Botanical Garden Kew; Bionomia*3; data made available online through platforms such as the Global Biodiversity Information Facility, Atlas of Living Australia, and World Flora Online. Other sources will also be used, like publications (Joyce et al. 2020) and "les herbonautes"*4, a citizen science platform. The short-term result is to produce a checklist of the vascular plants of Cambodia in multiple languages including Khmer. This project aligns with the FAIR (Findable, Accessible, Interoperable, Reusable) (Wilkinson et al. 2016) and CARE (Collective benefit, Authority to control, Responsability, Ethics) (Carroll et al. 2020) principles.

The osteology of Triisodon crassicuspis (Cope, 1882): New insights into the enigmatic "archaic" placental mammal group "Triisodontidae".

Following the end-Cretaceous mass extinction, mammals underwent an increase in body size, taxonomic diversity and ecological specialization throughout the Paleocene, exemplifying their adaptability. One especially enigmatic group is the "Triisodontidae", medium- to large-sized ungulate-like placentals from the Paleocene which are best known from their teeth that exhibit adaptations towards carnivory. The "triisodontids" were the first large carnivorous mammals and pre-date, and may have given rise to, Mesonychia, a group of more specialized placental carnivores. The "triisodontids" have been well-described from dental material, although very little is known about their postcrania. Here, we describe the postcrania of Triisodon crassicuspis-the most completely represented species of the genus to date-from a specimen (NMMNH P-72096) recovered from basal Torrejonian strata of the Nacimiento Formation in the San Juan Basin, New Mexico. Anatomical comparisons reveal that the forelimb long bones of Tri. crassicuspis are robust relative to its size, more so than other "triisodontids". Attachment sites on the ulna are evidence of well-developed muscles involved in powerful extension and flexion of the manus. In Tri. crassicuspis, the range of pronation-supination was limited as evident from the humeroradial morphology. Qualitative functional assessment of osteological features of the forelimb of Tri. crassicuspis is suggestive of terrestrial locomotion with at least moderate digging ability. Re-analyses of the dentition confirmed that Tri. crassicuspis had specializations for carnivory, and provide a body mass estimate of ca. 32-44 kg based on dental proxies. In summary, Tri. crassicuspis was a relatively large and powerful terrestrial animal, and one of the first known placentals to fill a largely carnivorous niche.

Multiple Speciation and Extinction Rate Shifts Shaped the Macro-Evolutionary History of the Genus Lycium Towards a Rather Gradual Accumulation of Species Within the Genus

The Neotropics are the most species-rich region on Earth, and spectacular diversification rates in plants are reported in plants, mostly occurring in oceanic archipelagos, making Neotropical and island plant lineages a model for macro-evolutionary studies. The genus Lycium in the Solanaceae family, originating from the Neotropics and exhibiting a unique disjunct geography across several islands, is therefore expected to experience exceptional diversification events. In this study, we aimed to quantify the diversification trajectories of the genus Lycium to elucidate the diversification events within the genus. We compiled a DNA matrix of six markers on 75% of all the species in the genus to reconstruct a dated phylogeny. Based on this phylogeny, we first revisited the historical biogeography of the genus. Then, we fitted a Compound Poisson Process on Mass Extinction Time model to investigate the following key evolutionary events: speciation rate, extinction rate, as well as mass extinction events. Our analysis confirmed that South America is the origin of the genus, which may have undergone a suite of successive long-distance dispersals. Also, we found that most species arose as recently as 5 million years ago, and that the diversification rate found is among the slowest rates in the plant kingdom. This is likely shaped by the multiple speciation and extinction rate shifts that we also detected throughout the evolutionary history of the genus, including one mass extinction at the early stage of its evolutionary history. However, both speciation and extinction rates remain roughly constant over time, leading to a gradual species accumulation over time.

Habitat Association Predicts Population Connectivity and Persistence in Flightless Beetles: A Population Genomics Approach Within a Dynamic Archipelago.

Habitat association has been proposed to affect evolutionary dynamics through its control on dispersal propensity, which is considered a key trait for lineage survival in habitats of low durational stability. The Habitat Constraint hypothesis predicts different micro- and macroevolutionary patterns for stable versus dynamic habitat specialists, but the empirical evidence remains controversial and in insects mostly derives from winged lineages. We here use genome-wide SNP data to assess the effect of habitat association on the population dynamics of two closely related flightless lineages of the genus Eutagenia (Coleoptera: Tenebrionidae), which are co-distributed across the Cyclades islands in the Eastern Mediterranean but are associated with habitat types of different presumed stability: the psammophilous lineage is associated with dynamic sandy coastal habitats, while the geophilous lineage is associated with comparatively stable compact soil habitats. Our comparative population genomic and demographic analyses support higher inter-island gene flow in the psammophilous lineage, presumably due to the physical properties of dynamic sand-dune habitats that promote passive dispersal. We also find consistent bottlenecks in the psammophilous demes, suggesting that lineage evolution in the dynamic habitat is punctuated by local extinction and recolonisation events. The inferred demographic processes are surprisingly uniform among psammophilous demes, but vary considerably among geophilous demes depending on historical island connectivity, indicating more stringent constraints on the dynamic habitat lineage. This study extends the Habitat Constraint hypothesis by demonstrating that selection on dispersal traits is not the only mechanism that can drive consistent differences in evolutionary dynamics between stable versus dynamic habitat specialists.

Functional diversity and resilience of bivalves after the Permian-Triassic mass extinction

The Permian-Triassic mass extinction was the largest extinction event in the Phanerozoic eon, with profound taxonomic and ecological effects on the ecosystem function. Functional diversity, a facet of biodiversity, could reflect the ecosystem function and stability. Although previous studies have shown that the functional richness of global marine organisms was decoupled from their taxonomic diversity during the mass extinctions, the evolution of functional diversity during the Permian-Triassic mass extinction and its aftermath is still under debate. The ecologically diverse clade bivalves may be more representative for understanding the evolution of functional diversity. To investigate the evolutionary dynamics of the functional diversity of bivalves, a global bivalve dataset of 8929 occurrences from the latest Permian to the Late Triassic was constructed. Functional richness, functional evenness, and functional redundancy were calculated to reflect the functional diversity in this study. Our results showed that the functional richness of bivalves was slightly affected by the Permian-Triassic mass extinction, decoupled from the significant decrease in taxonomic diversity. Meanwhile, a decrease in functional redundancy and an increase in functional evenness were observed after the mass extinction. In addition, bivalves showed high resilience to the mass extinction by maintaining the ecospace and reducing the functional redundancy. The high taxonomic diversity, high functional richness, high functional redundancy and relatively higher proportion of infaunal bivalves during the Late Triassic indicate that the Mesozoic marine revolution was already underway.

Insight into the Phylogenetic Relationships of Phasmatodea and Selection Pressure Analysis of Phraortes liaoningensis Chen & He, 1991 (Phasmatodea: Lonchodidae) Using Mitogenomes

Stick and leaf insects are a group among the Insecta that are famous for their extraordinary mimicry ability. Since the establishment of the Phasmatodea, their internal classification has been constantly revised. Mitochondrial genes as molecular markers have been widely used for species classification, but the phylogenetic relationships within the Phasmatodea remain to be thoroughly discussed. In the present study, five mitogenomes of Phasmatodea ranging from 15,746 bp to 16,747 bp in length were sequenced. Bayesian inference (BI) and maximum likelihood (ML) analyses were carried out based on a 13 PCGs data matrix (nt123) and a combined matrix of 13 PCGs and two rRNA genes (nt123_rRNA). The present study supports the conclusion that Phylliidae was the basal group of Neophasmatodea and confirms the monophyly of Lonchodinae and Necrosciinae, but it shows that Lonchodidae was polyphyletic. A sister group of Bacillidae and Pseudophasmatidae was also recovered. The phylogenetic tree based on the nt_123 dataset showed higher node support values. The construction of a divergent time tree in this study supported the conclusion that extant Phasmatodea originated in the Jurassic (170 Mya) and most lineages diverged after the Cretaceous–Paleogene extinction event. To explore whether the mitochondrial genes of Phraortes liaoningensis collected from high latitudes where low temperatures occur for eight months of the year are under selection pressure, this study used the branch-site model and the branch model to analyze the selection pressure on the 13 mitochondria protein-coding genes (PCGs). We found that both ND2 and ND4L of Ph. liaoningensis exhibited positive selection sites using the branch-site model. This study shows that a low-temperature environment causes mitochondrial genes to be selected to meet the energy requirements for survival.

Stoichiometric theory in optimal foraging strategy.

Understanding how organisms make choices about what to eat is a fascinating puzzle explored in this study, which employs stoichiometric modeling and optimal foraging principles. The research delves into the intricate balance of nutrient intake with foraging strategies, investigating quality and quantity-based food selection through mathematical models. The stoichiometric models in this study, encompassing producers and a grazer, unveils the dynamics of decision-making processes, introducing fixed and variable energetic foraging costs. Analysis reveals cell quota-dependent predation behaviors, elucidating biological phenomena such as "compensatory foraging behaviors" and the "stoichiometric extinction effect". The Marginal Value Theorem quantifies food selection, highlighting the profitability of prey items and emphasizing its role in optimizing foraging strategies in predator-prey dynamics. The environmental factors like light and nutrient availability prove pivotal in shaping optimal foraging strategies, with numerical results from a multi-species model contributing to a comprehensive understanding of the intricate interplay between organisms and their environment.

Extinction training suppresses activity of fear memory ensembles across the hippocampus and alters transcriptomes of fear-encoding cells.

Contextual fear conditioning has been shown to activate a set of "fear ensemble" cells in the hippocampal dentate gyrus (DG) whose reactivation is necessary and sufficient for expression of contextual fear. We previously demonstrated that extinction learning suppresses reactivation of these fear ensemble cells and activates a competing set of DG cells-the "extinction ensemble." Here, we tested whether extinction was sufficient to suppress reactivation in other regions and used single nucleus RNA sequencing (snRNA-seq) of cells in the dorsal dentate gyrus to examine how extinction affects the transcriptomic activity of fear ensemble and fear recall-activated cells. Our results confirm the suppressive effects of extinction in the dorsal and ventral dentate gyrus and demonstrate that this same effect extends to fear ensemble cells located in the dorsal CA1. Interestingly, the extinction-induced suppression of fear ensemble activity was not detected in ventral CA1. Our snRNA-seq analysis demonstrates that extinction training markedly changes transcription patterns in fear ensemble cells and that cells activated during recall of fear and recall of extinction have distinct transcriptomic profiles. Together, our results indicate that extinction training suppresses a broad portion of the fear ensemble in the hippocampus, and this suppression is accompanied by changes in the transcriptomes of fear ensemble cells and the emergence of a transcriptionally unique extinction ensemble.

The “Lochkovian-Pragian Event” re-assessed: New data from the low latitude shelf of peri-Gondwana

In the late Lochkovian a regression is documented in several areas of the world, followed by a transgression in the early Pragian. Connected with the eustatic variation, a minor extinction event occurred (“Lochkovian-Pragian Event”), affecting several fossil groups, a strong reduction of carbonate production and sedimentary facies changes. The Carnic Alps are a key area for studying this event, because lower Devonian rocks are widely exposed, representing diverse sedimentary environments from shallow water to relatively deep shelf. Fourteen sections were measured along the Carnic Alps across the Lochkovian-Pragian boundary. In the shallower part of the basin, both the Polinik and the Seekopf formations span the boundary, but evident erosional surfaces are observable in the field at the Lochkovian-Pragian boundary. Above the unconformity, at places the so-called megaclast horizon is present in the Seekopf Formation. In intermediate settings the Rauchkofel Fm. Is unconfomably followed by the Kellerwand Fm., and different parts of the upper Lochkovian and lower Pragian are missing in the various sections. In the deeper parts of the basin the transition from the La Valute Fm. To the Findenig Fm. Is slightly diachronous from the latest Lochkovian to the earliest Pragian; however, conodonts and tentaculitids are rare in the marly boundary beds, preventing a precise chronostratigraphic calibration of these levels. At places, evidence of subaerial exposure at the formational boundary is documented. In general, the hiatus seems to be larger in the western part of the Carnic Alps, in correspondence with the shallower parts of the succession, suggesting a sea level drop in the late Lochkovian, followed by a transgression in the Pragian. Data from the Carnic Alps are compared with those of other regions of North Gondwana to demonstrate that the sea-level variation at the Lochkovian-Pragian boundary are of global importance

Global Upper Kellwasser Event and its paleontological and litological reflection in the Bolshaya Barma, Akkyr, Ryauzyak and Kuk-Karauk carbonate sections of the western slope of the South Ural

The Frasnian and Famennian (F/F) boundary is one of the most discussed problems in the stratigraphy and paleontology. This interval is characterized worldwide by a global geological crisis and the associated the largest extinction event of the Phanerozoic, known as the Upper Kellwasser Event (UK). In the studied carbonate sections of the western slope of the South Urals (Bolshaya Barma, Akkyr, Ryauzyak and Kuk-Karauk) the UK event is reflected as a global bio event. A sharp change of the taxonomic composition of conodont complexes is clearly recorded in the brachiopod shell stones at the Famennian Barma Horizon bottom. In the uppermost Askyn Horizon, close to the F/F boundary, Frasnian species of the genera Ancyrognathus and Palmatolepis die out, and the genera Ancyrodella and Belodella become totally extinct. At the end of the Frasnian time in all studied sections the palmatolepid (pelagic) biofacies gives way to the icriodid (shallow water) one.

Seasonal trends and light extinction effects of PM2.5 chemical composition from 2021 to 2022 in a typical industrial city of central China

This study investigates the concentrations, chemical compositions, and sources of PM2.5 in Huangshi, China. Daily average PM2.5 levels ranged from 8.43 to 193.08 μg m−3, with an annual mean of 54.13 μg m−3, exceeding China's annual secondary standard of 35 μg m−3. Seasonal mean concentrations peaked in winter and were lowest in summer. Organic carbon (OC) and elemental carbon (EC) had annual means of 4.89 μg m−3 and 0.94 μg m−3, respectively. Water-soluble inorganic ions (WSIIs) accounted for 52.17% of PM2.5, with NO3−, SO42−, and NH4+ being the major components. The NO3−/SO42− ratio averaged 1.65, indicating a transition from coal combustion to vehicle emissions as the primary pollution source. Chemical mass reconstruction revealed that NH4NO3, (NH4)2SO4, and organic matter (OM) accounted for 65.3% of PM2.5 mass. Seasonal variations in light extinction (bext) highlighted the impact of secondary inorganic salts on visibility, with an annual average bext of 346.30 ± 246.98 Mm−1. Airmass clusters and potential source region analysis suggested PM2.5 and its components were primarily originated from local and nearby regions. These findings underscore the effectiveness of local pollution control measures, changing pollution sources, and the necessity for targeted emission controls to improve air quality and visibility in urban areas.

Cretaceous stratigraphy in the Songliao Basin, NE China

The Songliao Basin is one of the largest non-marine oil- and gas-bearing basins that developed during the Cretaceous period, recording an almost complete Cretaceous stratigraphy. With oil and gas exploration, as well as the Continental Scientific Drilling Project of Cretaceous Songliao Basin (CCSD-SK) (2006–21), significant progress has been made on the stratigraphy of the Songliao Basin. The Songliao Basin is therefore important for understanding the non-marine Cretaceous system. Based on lithostratigraphy, sequence stratigraphy, biostratigraphy, geochronology, magnetostratigraphy and cyclostratigraphy, a comprehensive stratigraphical framework of the Songliao Basin has been established in this study. The Lower Cretaceous strata (Hauterivian–Albian) of the basin are dominated by volcanic–sedimentary deposits, while the lower-middle Upper Cretaceous (Cenomanian mid-Campanian) strata are dominated by lacustrine deposits. The upper Upper Cretaceous strata (late Campanian–Maastrichtian) are dominated by fluvial–lacustrine deposits. Fossils are very abundant in the Songliao Basin, and three biotas – the Jehol Biota sensu lato , the Songhuajiang Biota and the Mingshui Biota – are recognized in the Songliao Basin. Furthermore, several important geological events, such as lake anoxic events, seawater incursion events and the K/Pg boundary extinction events are all recorded in the Songliao Basin.