Search

Gastropods, as one of the most common invertebrates in shallow marine environments, were heavily impacted by the Permian–Triassic mass extinction (PTME), with severe loss of diversity and remarkable dwarfism of body size. Here, we report a new gastropod fauna from the Permian–Triassic carbonates of Zuodeng, Guangxi Province, South China. Five species belonging to five genera and two indeterminate taxa are identified. The Zuodeng fauna is dominated by Paleozoic holdover taxa, including Holopea teres, Protostylus sp., and Wannerispira shangganensis although most of them are found in the basal Triassic microbialites. Three gastropod communities have been recognized by cluster analysis. Further morphological analyses show that the changing pattern of disparity, with diversity decreasing from community II to III, fits the interior-reduction model. In addition, the morphospace of community in microbialites is higher than those in non-microbialite bearing beds at Zuodeng, shedding new light on the ecological role of microbialites during the Permian-Triassic environmental stress. [ABSTRACT FROM AUTHOR]

The miniaturization of organisms during the Permian-Triassic mass extinction, as an ecological strategy in response to environmental devastation, has been widely recognized in diverse marine invertebrates. Previous studies on the extinction process and miniaturization of foraminifers in the Permian-Triassic interval have relied on the fossil record of the low-latitude Paleotethys or a global database, although data and materials from the high-latitude Neotethys region are still rare. To reveal the evolutionary patterns and spatial variability of foraminifers at different latitudes and paleogeographic contexts, here we investigated the fossil distribution and size variation of foraminifers in the Selong Section of southern Tibet, located in the mid-latitude Neotethys of the Southern Hemisphere during the Permian-Triassic transition. The results show that the foraminifer of the Selong Section experienced a two-pulsed extinction (total species extinction rate of 71%), consistent with the time in South China but with a lower magnitude of extinction. Meanwhile, the data show that foraminiferal test volume was significantly miniaturized following the first pulse of extinction event: the mean size of post-extinction foraminifer was only 15% of that in the pre-extinction, mainly reflected by the disappearance of large forms as well as occurrences of smaller survivors and originators. Combined with the South China record, size data from southern Tibet indicate that the miniaturization of foraminifera is synchronous in the Paleotethys and Neotethys but smaller in magnitude in the Neotethys. We propose that ocean anoxia and acidification may be the environmental pressures leading to local and global foraminiferal miniaturizations, along with global warming, which might play a dominant role. [ABSTRACT FROM AUTHOR]

Simple Summary: Primary themes in intergenerational justice are a healthy environment, the perpetuation of Earth's biodiversity, and the sustainable management of the biosphere. These goals demand transformative changes to biodiversity management, especially when considering the predicted sixth mass extinction. Reproduction and advanced biotechnologies, biobanks of germplasm and somatic cells, and conservation breeding programs (RBCs) provide a transformative change to perpetuate biodiversity irrespective of environmental targets, ecosystem collapses, and other sixth mass extinction drivers. Future potentials for RBCs include assisted evolution, species restoration, and the extension of the biosphere through interplanetary and interstellar colonization. We address these themes with amphibian models to introduce the MDPI Special Issue, The Sixth Mass Extinction and Species Sustainability through Reproduction and Advanced Biotechnologies, Biobanking, and Conservation Breeding Programs. Primary themes in intergenerational justice are a healthy environment, the perpetuation of Earth's biodiversity, and the sustainable management of the biosphere. However, the current rate of species declines globally, ecosystem collapses driven by accelerating and catastrophic global heating, and a plethora of other threats preclude the ability of habitat protection alone to prevent a cascade of amphibian and other species mass extinctions. Reproduction and advanced biotechnologies, biobanking of germplasm and somatic cells, and conservation breeding programs (RBCs) offer a transformative change in biodiversity management. This change can economically and reliably perpetuate species irrespective of environmental targets and extend to satisfy humanity's future needs as the biosphere expands into space. Currently applied RBCs include the hormonal stimulation of reproduction, the collection and refrigerated storage of sperm and oocytes, sperm cryopreservation, in vitro fertilization, and biobanking of germplasm and somatic cells. The benefits of advanced biotechnologies in development, such as assisted evolution and cloning for species adaptation or restoration, have yet to be fully realized. We broaden our discussion to include genetic management, political and cultural engagement, and future applications, including the extension of the biosphere through humanity's interplanetary and interstellar colonization. The development and application of RBCs raise intriguing ethical, theological, and philosophical issues. We address these themes with amphibian models to introduce the Multidisciplinary Digital Publishing Institute Special Issue, The Sixth Mass Extinction and Species Sustainability through Reproduction Biotechnologies, Biobanking, and Conservation Breeding Programs. [ABSTRACT FROM AUTHOR]

The causes of heterogeneity in evolutionary rates are a key question in macroevolution. Origination and extinction rates are closely related to abiotic factors, such as climate 1,2 and geography, 3,4 as well as biotic factors such as taxonomic richness 5,6 and morphology, 7 which are influenced by phylogeny. 8,9 Studies on the relationship between morphology and macroevolution have focused on morphological traits, including body size, 6,7,9 shape, 10 color, 11,12 and complexity, 13,14,15 and have proposed biological laws, such as the zero-force evolutionary law 16 and Cope's rule. 17 However, the relationship between morphological complexity and turnover rates remains poorly defined because of the lack of suitable measures for various subjects. 18,19 Here, we establish a quantitative method, the two-dimensional ornamentation index (2D-OI), which allows the description of the ornamental complexity of ammonoids. Ammonoids are one of the most abundant and well-studied fossil groups, with complex conch structures. 20 Ammonoids display some similarities with trilobites and mammals 21,22 in terms of their high evolutionary rates; however, the underlying mechanisms remain elusive. Moreover, ammonoids exhibit marked heterogeneity in turnover rates across spatiotemporal scales 23 and clades, 23,24 making them key clades for investigating the relationship between turnover rates and morphological complexity. The results show that morphologically complex genera and species often have higher origination and extinction rates than morphologically simple taxa. Diversity fluctuations of taxa with complex ornamentation generally overimprint and control the overall net diversification rates of ammonoids. This double-edged sword of rapid evolution and increased extinction risk driven by complex morphologies has significant implications for our understanding of how species survive over geological timescales. • New method ("2D-OI") to estimate the ornamentation complexity in shelled animals • Complex morphologic ammonoids generally exhibit shorter longevity than simple taxa • Complex morphologic taxa have higher origination and extinction rates than simple taxa • Complex taxa dominate overall fluctuations in ammonoid diversification rates Miao et al. show that morphologically complex ammonoid genera and species generally have shorter longevity and faster rates of turnover than morphologically simple taxa. The diversification rate of taxa with complex morphology controls the apparent overall diversification fluctuations of ammonoids. [ABSTRACT FROM AUTHOR]

Elevated temperatures persisted for an anomalously protracted interval following pulsed volcanic carbon release associated with the end-Permian mass extinction, deviating from the expected timescale of climate recovery following a carbon injection event. Here, we present evidence for enhanced reverse weathering--a CO2 source--following the end-Permian mass extinction based on the lithium isotopic composition of marine shales and cherts. We find that the average lithium isotopic composition of Lower Triassic marine shales is significantly elevated relative to that of all other previously measured Phanerozoic marine shales. Notably, the record generated here conflicts with carbonate-based interpretations of the lithium isotopic composition of Early Triassic seawater, forcing a re-evaluation of the existing framework used to interpret lithium isotopes in sedimentary archives. Using a stochastic forward lithium cycle model, we demonstrate that elevated reverse weathering is required to reproduce the lithium isotopic values and trends observed in Lower Triassic marine shales and cherts. Collectively, this work provides direct geochemical evidence for enhanced reverse weathering in the aftermath of Earth's most severe mass extinction. [ABSTRACT FROM AUTHOR]

Studies of the history of life provide an interesting case study of how the questions scientists can ask, and from which they expect reliable answers, change over time. Some of these changes reflect the introduction of new technology or methodological advances in other fields that open new opportunities; other changes reflect an evolving perspective on what constitutes important research questions or the integration of multiple streams of information. In this contribution, I consider the changing nature of questions in paleontology, largely focusing on English-speaking paleontologists since the mid-twentieth century. Rather than bemoaning the field’s limitations, paleontologists have pioneered techniques to identify and often correct preservation and collecting biases in the fossil record. Rigorous methods to infer and test phylogenies have been integrated with molecular clock studies to infer branch-points in phylogeny, and with insights from comparative developmental studies, which together inform our understanding of evolutionary dynamics, particularly novelty. Together, these advances have changed the questions paleontologists can address about the history of life, eliminating some questions (particularly in paleoecology), but greatly expanding research programs in other areas as well as collaborations with biologists and other Earth scientists. I suggest that the questions driving paleontologists have evolved from primarily descriptive and explanatory to increasingly analytical and integrative. These trends are briefly illustrated with examples from studies of the Ediacaran-Cambrian diversification of animals, and from studies of mass extinctions.

Many modern extinction drivers are shared with past mass extinction events, such as rapid climate warming, habitat loss, pollution and invasive species. This commonality presents a key question: can the extinction risk of species during past mass extinction events inform our predictions for a modern biodiversity crisis? To investigate if it is possible to establish which species were more likely to go extinct during mass extinctions, we applied a functional trait-based model of extinction risk using a machine learning algorithm to datasets of marine fossils for the end-Permian, end-Triassic and end-Cretaceous mass extinctions. Extinction selectivity was inferred across each individual mass extinction event, before testing whether the selectivity patterns obtained could be used to 'predict' the extinction selectivity exhibited during the other mass extinctions. Our analyses show that, despite some similarities in extinction selectivity patterns between ancient crises, the selectivity of mass extinction events is inconsistent, which leads to a poor predictive performance. This lack of predictability is attributed to evolution in marine ecosystems, particularly during the Mesozoic Marine Revolution, associated with shifts in community structure alongside coincident Earth system changes. Our results suggest that past extinctions are unlikely to be informative for predicting extinction risk during a projected mass extinction.

Abstract This study investigates the mechanisms underlying the varied climate changes witnessed during mass extinctions in the Phanerozoic Eon. Climate shifts during mass extinctions have manifested as either predominant global cooling or predominant warming, yet the causes behind these occurrences remain unclear. We emphasize the significance of sedimentary rock temperature in comprehending these climate shifts. Our research reveals that low-temperature heating of sulfide leads to global cooling through the release of sulfur dioxide (SO2), while intermediate-temperature heating of hydrocarbons and carbonates releases substantial carbon dioxide (CO2), contributing to global warming. High-temperature heating additionally generates SO2 from sulfate, further contributing to global cooling. Different degrees of contact heating of the host rock can lead to different dominant volatile gas emissions, crucially driving either warming or cooling. Moreover, medium to high-temperature shock-heating resulting from asteroid impacts produces soot from hydrocarbons, also contributing to global cooling. Large-scale volcanic activity and asteroid impacts are both events that heat rocks, emitting the same gases and particles, causing climate changes. The findings elucidate the critical role of heating temperature and heating time in understanding major climate changes during mass extinctions.

We live in a time of accelerated biological extinctions that has the potential to mirror past mass extinction events. However, the rarity of mass extinctions and the restructuring of diversity they cause complicate direct comparisons between the current extinction crisis and earlier events. Among animals, turtles (Testudinata) are one of few groups that have both a rich fossil record and sufficiently stable ecological and functional roles to enable meaningful comparisons between the end-Cretaceous mass extinction (∼66 Ma) and the ongoing wave of extinctions. Here we analyze the fossil record of the entire turtle clade and identify two peaks in extinction rates over their evolutionary history. The first coincides with the Cretaceous-Paleogene transition, reflecting patterns previously reported for other taxa. The second major extinction event started in the Pliocene and continues until now. This peak is detectable only for terrestrial turtles and started much earlier in Africa and Eurasia than elsewhere. On the basis of the timing, geography, and functional group of this extinction event, we postulate a link to co-occurring hominins rather than climate change as the cause. These results lend further support to the view that negative biodiversity impacts were already incurred by our ancestors and related lineages and demonstrate the severity of this continued impact through human activities. [ABSTRACT FROM AUTHOR]

At Tanis, a unique bi‐directional sediment package occurs precisely at the Cretaceous‐Paleogene (K‐Pg) boundary, recording the first hours of the Paleogene in uncommonly fine temporal detail. The impact ejecta‐bearing sediment package was rapidly emplaced by two massive, ∼10‐m‐high, potentially impact‐triggered surges, that inundated a steep, deeply incised paleo river valley from the direction of the contemporaneous Western Interior Seaway (WIS). Intermingling of fresh‐ and salt‐water fossils at Tanis, coeval brackish water indicators in the nearby region, and historical tsunami observations, suggest that the WIS paleoshoreline was nearby Tanis at K‐Pg time. The interpreted timing for deposition (including ejecta infall) of ∼1–2‐hr immediately post‐impact precludes a direct tsunami from the Chicxulub impact site, which would have required much more than 10 hr to reach Tanis. Seismic waves from the Mw ∼ 11 Chicxulub earthquake, arriving just minutes post‐impact, might have triggered the surge, for example, via seismic excitation of large water waves in the WIS, as proposed by DePalma et al. (2019, https://doi.org/10.1073/pnas.1817407116). Here, we explore this mechanism via a simple mathematical model of seismic excitation and propagation of a water wave into a shallow river and upstream. Matching the observations implies a relatively long source process time of many minutes, such as generated by Chicxulub crater rebound processes, in order to explain sufficient upriver amplitudes and advective transport. Atmospheric waves due to the expanding Chicxulub ejecta curtain might have provided a smaller, secondary contribution during triggering. Thus, the mechanism(s) for the surges at Tanis are now better‐constrained, yet remain incompletely resolved. Plain Language Summary: A remarkable geological record at the "Tanis" site (North Dakota) shows that two ∼10 m high tsunami‐like surges occurred on a point bar along a river upstream from the then existing Western Interior Seaway (WIS). The surge deposits are interpreted to have occurred within 1–2 hr of the Chicxulub impact associated with the end‐Cretaceous mass extinction including the dinosaurs, and are challenging to explain via traditional tsunami mechanisms because they occurred too soon after the impact to have been tsunami waves traveling from the impact site. Alternative explanations include excitation of large water waves in the WIS due to seismic shaking from the magnitude ∼11 impact‐generated earthquake or atmospheric effects from the expanding impact ejecta curtain. Here, we explore one potential triggering mechanism via a simple mathematical model of direct seismic excitation and propagation of a water wave into a shallow river and upstream. This model shows the difficulty of generating the observed surge deposits unless the timescale for impact‐generated seismic waves is much longer than is commonly presumed. Thus the actual triggering mechanism(s) of the Tanis depositional surges remains incompletely resolved, while the sediment package bears a rich source of information about the global effects of the Chicxulub impact. Key Points: An ∼10 m surge event coincident with the Chicxulub impact transported mixed freshwater/marine organisms up the Tanis river valleyNew modeling confirms limitations on the inland transport of marine fossils and helps to constrain the impact‐related triggering mechanismOther potential triggering mechanisms and strategic avenues of future study are discussed [ABSTRACT FROM AUTHOR]

This study investigates the mechanisms underlying the varied climate changes witnessed during mass extinctions in the Phanerozoic Eon. Climate shifts during mass extinctions have manifested as either predominant global cooling or predominant warming, yet the causes behind these occurrences remain unclear. We emphasize the significance of sedimentary rock temperature in comprehending these climate shifts. Our research reveals that low-temperature heating of sulfide leads to global cooling through the release of sulfur dioxide (SO2), while intermediate-temperature heating of hydrocarbons and carbonates releases substantial carbon dioxide (CO2), contributing to global warming. High-temperature heating additionally generates SO2 from sulfate, further contributing to global cooling. Different degrees of contact heating of the host rock can lead to different dominant volatile gas emissions, crucially driving either warming or cooling. Moreover, medium to high-temperature shock-heating resulting from asteroid impacts produces soot from hydrocarbons, also contributing to global cooling. Large-scale volcanic activity and asteroid impacts are both events that heat rocks, emitting the same gases and particles, causing climate changes. The findings elucidate the critical role of heating temperature and heating time in understanding major climate changes during mass extinctions. [ABSTRACT FROM AUTHOR]

Explanations for major catastrophes in the history of life commonly focus on their time-spans. Less biotic crises are worth attention as well, however, which requires their investigation in a longer-lasting context. The present study relates the Taghanic (Givetian) and mid-Carboniferous (Serpukhovian) biotic crises to some long-term changes in their environmental developments. The trends in these developments are interpreted on the basis of changes of the global sea level, the global average temperatures, the total surface area of exposed land, the total number of lithospheric plates, and the concentration of atmospheric oxygen. It is found that the Taghanic and mid-Carboniferous biotic crises can be related directly or indirectly to some long-term environmental changes.

The end‐Neoproterozoic transition marked a gradual but permanent shift between distinct configurations of Earth's biosphere. This interval witnessed the demise of the enigmatic Ediacaran Biota, ushering in the structured trophic webs and disparate animal body plans of Phanerozoic ecosystems. However, little consensus exists on the reality, drivers, and macroevolutionary implications of end‐Neoproterozoic extinctions. Here we evaluate potential drivers of late‐Neoproterozoic turnover by addressing recent findings on Ediacaran geochronology, the persistence of classical Ediacaran macrobionts into the Cambrian, and the existence of Ediacaran crown‐group eumetazoans. Despite renewed interest in the possibility of Phanerozoic‐style 'mass extinctions' in the latest Neoproterozoic, our synthesis of the available evidence does not support extinction models based on episodic geochemical triggers, nor does it validate simple ecological interpretations centred on direct competitive displacement. Instead, we argue that the protracted and indirect effects of early bilaterian innovations, including escalations in sediment engineering, predation, and the largely understudied impacts of reef‐building, may best account for the temporal structure and possible selectivity of late‐Neoproterozoic extinctions. We integrate these processes into a generalised model of early eumetazoan‐dominated ecologies, charting the disruption of spatial and temporal isotropy on the Ediacaran benthos as a consequence of diversifying macrofaunal interactions. Given the nature of resource distribution in Ediacaran ecologies, the continuities among Ediacaran and Cambrian faunas, and the convergent origins of ecologically disruptive innovations among bilaterians we suggest that the rise of Phanerozoic‐type biotas may have been unstoppable. [ABSTRACT FROM AUTHOR]

[Display omitted] • Decarbonation of skarn deposits was more efficient than other carbon sources. • Skarn deposits may have contributed to the rise of CO 2 concentration at 145 Ma. • Skarn deposits may have influenced the ecological system in East Asia. Magmatic-hydrothermal systems transport metal, sulfur, and carbon from deep to shallow crust, providing materials to the society and potentially affecting Earth's long-term environment. The fluxes of elements and, accordingly the environmental effects, are ultimately functions of the time-integrated amounts and durations of magmatic-hydrothermal system. In this study, we calculate the duration of prograde metamorphism induced by fluid infiltration and amount of carbon released by skarn ore deposits. This study finds that skarn ore deposits can decarbonize CO 2 at an efficiency up to 1014 g/(y.km3), which is much higher than volcanism on different tectonic settings. The CO 2 flux of skarn deposits increased from late Jurassic to early Cretaceous and reached a maximum value to 7.8 Mt/y at J/K boundary. Our finding provided an previously unquantified but important outgassing source in the subduction zone. This result consistent with global warming pattern based on global sedimentary records. The maximum outgassing at J/K boundary may have important impact on global warming and perhaps mass extinction. [ABSTRACT FROM AUTHOR]

The Permian--Triassic climate crisis can provide key insights into the potential impact of horizon threats to modern-day biodiversity. This crisis coincides with the same extensive environmental changes that threaten modern marine ecosystems (i.e., thermal stress, deoxygenation and ocean acidification), but the primary drivers of extinction are currently unknown. To understand which factors caused extinctions, we conducted a data analysis to quantify the relationship (anomalies, state-shifts and trends) between geochemical proxies and the fossil record at the most intensively studied locality for this event, the Meishan section, China. We found that δ18Oapatite (paleotemperature proxy) and δ114/110Cd (primary productivity proxy) best explain changes in species diversity and species composition inMeishan's paleoequatorial setting. These findings suggest that the physiological stresses induced by ocean warming and nutrient avail- ability played a predominant role in driving equatorial marine extinctions during the Permian--Triassic event. This research enhances our understanding of the interplay between environmental changes and extinction dynamics during a past climate crisis, presenting an outlook for extinction threats in the worst-case "Shared Socioeconomic Pathways (SSP5-8.5)" scenario. [ABSTRACT FROM AUTHOR]

Copyright of Studia Ethnologica Croatica is the property of Studia Ethnologica Croatica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

D. Jablonski [Proc. Natl. Acad. Sci. U.S.A. 99, 8139-8144 (2002)] coined the term "dead clades walking" (DCWs) to describe marine fossil orders that experience significant drops in genus richness during mass extinction events and never rediversify to previous levels. This phenomenon is generally interpreted as further evidence that the macroevolutionary consequences of mass extinctions can continue well past the formal boundary. It is unclear, however, exactly how long DCWs are expected to persist after extinction events and to what degree they impact broader trends in Phanerozoic biodiversity. Here we analyze the fossil occurrences of 134 skeletonized marine invertebrate orders in the Paleobiology Database (paleobiodb.org) using a Bayesian method to identify significant change points in genus richness. Our analysis identifies 70 orders that experience major diversity losses without recovery. Most of these taxa, however, do not fit the popular conception of DCWs as clades that narrowly survive a mass extinction event and linger for only a few stages before succumbing to extinction. The median postdrop duration of these DCW orders is long (>30 Myr), suggesting that previous studies may have underestimated the long-term taxonomic impact of mass extinction events. More importantly, many drops in diversity without recovery are not associated with mass extinction events and occur during background extinction stages. The prevalence of DCW orders throughout both mass and background extinction intervals and across phyla (>50% of all marine invertebrate orders) suggests that the DCW pattern is a major component of macroevolutionary turnover.

Given the Indian block’s ancient association with Gondwana and subsequent separation from Africa, then Madagascar, then the Seychelles, vicariance has often been invoked to explain the distribution of some of India’s extant biota that might have had Gondwanan origins. Here I review phylogenetic studies and fossil data of Indian tetrapods to ascertain the contribution of dispersal and vicariance in shaping the assemblage. Paleogene dispersal into India accounts for almost all of the tetrapod clades in India. Vicariance is invoked for three groups, all fossorial; the caecilians, the frog family Nasikabatrachidae and the blindsnake family Gerrhopilidae. This review concludes that practically all of India’s Late Cretaceous tetrapod fauna (of Gondwanan origin) was extirpated during the Cretaceous-Paleogene mass extinction, which may have been exacerbated by the coeval volcanism associated with the emplacement of the Deccan Trap large igneous province. Subsequently, the tetrapod fauna was built up by incoming elements as India advanced towards Asia, docking with the continent in the Paleogene.

Mass extinctions have fundamentally altered the structure of the biosphere throughout Earth's history. The ecological severity of mass extinctions is well studied in marine ecosystems by categorizing marine taxa into functional groups based on 'ecospace' approaches, but the ecological response of terrestrial ecosystems to mass extinctions is less well understood due to the lack of a comparable methodology. Here, we present a new terrestrial ecospace framework that categorizes fauna into functional groups as defined by tiering, motility and feeding traits. We applied the new terrestrial and traditional marine ecospace analyses to data from the Paleobiology Database across the end-Triassic mass extinction—a time of catastrophic global warming—to compare changes between the marine and terrestrial biospheres. We found that terrestrial functional groups experienced higher extinction severity, that taxonomic and functional richness are more tightly coupled in the terrestrial, and that the terrestrial realm continued to experience high ecological dissimilarity in the wake of the extinction. Although signals of extinction severity and ecological turnover are sensitive to the quality of the terrestrial fossil record, our findings suggest greater ecological pressure from the end-Triassic mass extinction on terrestrial ecosystems than marine ecosystems, contributing to more prolonged terrestrial ecological flux. [ABSTRACT FROM AUTHOR]

Bentonites are widely distributed and developed in several layers in the Ordovician-Silurian boundary, which is of great significance for the study of stratigraphic chronology, stratigraphic correlation, event stratigraphy and mass extinction in the penod. The zircon U-Pb dating of bentonites in the bottom of Upper Ordovician-Lower Silurian Longmaxi Formation in Yongshan area on the western margin of Yangtze Plate yields the weighted average age of 443.5± 1.7 Ma, which defines the sedimentary age of the strata and provides a reliable basis for the study of Ordovician-Silurian volcanic eruption event and stratigraphic chronology on the western margin of Yangtze Plate, as well as basic information for the establishment of Ordovician-Silurian high-resolution stratigraphic framework on the periphery of Yangtze Plate. The trace element characteristics of zircon show the features of I-type granite formed in magmatic arc or organic belt. The multi-stage and high-frequency volcanic activity in the Late Ordovician-Early Silurian is possibly the dominant factor causing the mass extinction. [ABSTRACT FROM AUTHOR]

This paper builds upon a recent corpus of popular science that has elevated previously unsung members of the biosphere—"worts." It argues that the corpus constitutes a new natural theology, a search for meaning in the biosphere, and suggests a theological underpinning to what its authors intuit: that worts give meaning. To do this, the paper draws on Eduardo Kohn's How Forests Think (2013) and its examination of meaning as a ubiquitous feature of the multispecies ecosystem. Following on from Kohn, two key arguments are made. First, Kohn's posthuman anthropology is compatible with a Thomist treatment of organisms in terms of their distinct, life-orientated telos. Second, the current context of potential human extinction puts a life-orientated telos in a new light, reviving the validity of teleological thinking. Sharing the fate of nonhuman subjects, rather than treating them as scientific objects, authors and readers of the new natural theology find meaning among worts. [ABSTRACT FROM AUTHOR]

Based on the global occurrence dataset, the shift in taxonomic and functional diversity of bivalves at the Triassic/Jurassic transition was examined herein. There is a noticeable decline in diversity at many taxonomic levels (generic, family, and order) along the Triassic/Jurassic boundary. Test changes in the functional diversity (e.g., life habits, mobility levels, and feeding mode) revealed that the percentage of mobile exceeded stationary taxa after the end of the Triassic crisis, while no major changes were observed in the life habit or feeding mode. By the Sinemurian, diversity reached the pre-extinction levels. A significant difference was also found between survivors' longevity and extinct taxa, where the Early Jurassic (Hettangian) fauna have a longer duration relative to those that became extinct. The Triassic/Jurassic boundary is marked by a marked sea-level fall and a decrease in the mean Sea Surface Temperature (SST), which is associated with increasing siliciclastic and decreasing carbonate rocks. The latter may also point to ocean acidification at the Triassic/Jurassic boundary. The geographic range size of bivalves is slightly changed by the end of the Triassic, where the taxa are slightly characterized by narrower ranges. Hence, the geographic range size, the result of ecophysiology, plays a major role in determining the extinction risk. The difference in the magnitude of the diversity loss (i.e., taxonomically vs. functionally) indicated that the shallower marine habitat destruction resulting from the sea-level fall is the primary cause of the Triassic/Jurassic mass extinction. [ABSTRACT FROM AUTHOR]

Understanding species responses to climatic change over extended timescales helps elucidate past and future extinction events. Amphibians are one of the most environmentally sensitive groups and yet showed high resilience to the Cretaceous-Paleogene (KPg) mass extinction, an event marked by sudden cooling and drought. To understand this past resilience and the associated filter mechanisms, we investigated the evolutionary history of key survival traits (body size and lifestyle) and explored climate-driven body-size selectivity of modern anuran assemblages. We found clear environment constraints on present-day anurans, where extreme temperatures and high seasonality filter against extreme-sized species. Our fossil-extant phylogenetic reconstruction reveals that anuran assemblages surrounding the KPg were mostly medium-sized species but large anuran species went extinct at the KPg, which is consistent with the uneven size-resilience to climate across modern anurans. Additionally, we found that cooling periods were marked by accelerated body-size diversification in anurans, and we inferred a close association between the evolution of arboreal frogs and angiosperms. Using the climate resilience of modern species as baselines, we estimate that future climate change will impact tropical anurans the most, where up to ∼500 species may face increased climate-related extinction pressure by 2100. Here we show that size-extinction selectivity in anurans is consistent over time and space, with extreme climate conditions filtering out larger and smaller species, conditions of which are likely to become increasingly prevalent in the future.

Biologists have long sought to quantify the number of species on Earth. Often missing from these efforts is the contribution of microorganisms, the smallest but most abundant form of life on the planet. Despite recent large‐scale sampling efforts, estimates of global microbial diversity span many orders of magnitude. It is important to consider how speciation and extinction over the last 4 billion years constrain inventories of biodiversity. We parameterized macroevolutionary models based on birth–death processes that assume constant and universal speciation and extinction rates. The models reveal that richness beyond 1012 species is feasible and in agreement with empirical predictions. Additional simulations suggest that mass extinction events do not place hard limits on modern‐day microbial diversity. Together, our study provides independent support for a massive global‐scale microbiome while shedding light on the upper limits of life on Earth. [ABSTRACT FROM AUTHOR]

The body size of marine ectotherms is often negatively correlated with ambient water temperature, as seen in many clades during the hyperthermal crisis of the end‐Permian mass extinction (c. 252 Ma). However, in the case of ostracods, size changes during ancient hyperthermal events are rarely quantified. In this study, we evaluate the body size changes of ostracods in the Aras Valley section (northwest Iran) in response to the drastic warming during the end‐Permian mass extinction at three taxonomic levels: class, order, species. At the assemblage level, the warming triggers a complete species turnover in the Aras Valley section, with larger, newly emerging species dominating the immediate post‐extinction assemblage for a short time. Individual ostracod species and instars do not show dwarfing or a change in body size as an adaptation to the temperature stress during the end‐Permian crisis. This may indicate that the ostracods in the Aras Valley section might have been exceptions to the temperature–size rule (TSR), using an adaptation mechanism that does not involve a decrease in body size. This adaptation might be similar to the accelerated development despite constant instar body sizes that can be observed in some recent experimental studies of ostracod responses to thermal stress. [ABSTRACT FROM AUTHOR]

Despite mounting evidence that industrial animal agriculture is a formidable force of climate change and mass extinction, many humans remain impervious to this knowledge. Eating Our Way to Extinction is a timely documentary that takes this issue head on. This film review is guided by Alexandra Juhasz's explanation of media praxis as 'an enduring, mutual, and building tradition that theorizes and creates the necessary conditions for media to play an integral role in cultural and individual transformation' (299). Eating Our Way to Extinction attends to some of the most popular strawman arguments against veganism and is widely accessible. That being said, it falls short of its sociopolitical potential because it is beholden to the capitalist-colonial norms of self-interested individualism, promotion of consumerism over movement-building, and using Indigenous peoples as a means to an end. Eating Our Way to Extinction contrasts a worldview based on extraction and domination with one that could actually shift the tide of climate change. It then follows the logic of the extractive worldview by promoting self-interested solutions to a problem that is only exacerbated by capitalism. The fact that Eating Our Way to Extinction acknowledges that Indigenous peoples are more adept at living in an ecologically harmonious way, then silos its viewers into the very mindset that is driving the problem is where the documentary falls flat. At its heart, Eating Our Way to Extinction relies on the Western colonial logics of individualism and capitalism that undercut the social justice demands of veganism. [ABSTRACT FROM AUTHOR]

Mass extinction at the Cretaceous-Paleogene (K-Pg) boundary coincides with the Chicxulub bolide impact and also falls within the broader time frame of Deccan trap emplacement. Critically, though, empirical evidence as to how either of these factors could have driven observed extinction patterns and carbon cycle perturbations is still lacking. Here, using boron isotopes in foraminifera, we document a geologically rapid surface-ocean pH drop following the Chicxulub impact, supporting impact-induced ocean acidification as a mechanism for ecological collapse in the marine realm. Subsequently, surface water pH rebounded sharply with the extinction of marine calcifiers and the associated imbalance in the global carbon cycle. Our reconstructed water-column pH gradients, combined with Earth system modeling, indicate that a partial ∼50% reduction in global marine primary productivity is sufficient to explain observed marine carbon isotope patterns at the K-Pg, due to the underlying action of the solubility pump. While primary productivity recovered within a few tens of thousands of years, inefficiency in carbon export to the deep sea lasted much longer. This phased recovery scenario reconciles competing hypotheses previously put forward to explain the K-Pg carbon isotope records, and explains both spatially variable patterns of change in marine productivity across the event and a lack of extinction at the deep sea floor. In sum, we provide insights into the drivers of the last mass extinction, the recovery of marine carbon cycling in a postextinction world, and the way in which marine life imprints its isotopic signal onto the geological record.

Paleobotanists debate whether the Cretaceous/Paleogene boundary (KPB) event was selective. As the hypothesis that the KPB event selected for plants with fast-return leaf economic traits (e.g. deciduousness) has lost empirical support in recent investigations, researchers have turned to alternative hypotheses to explain an abrupt decline in primary productivity across the KPB. Two contemporary hypotheses designed to explain selectivity among plants across the KPB are that (1) polyploids exhibited greater survivorship than their diploid progenitors or counterparts (i.e. the KPB-whole genome duplication or WGD hypothesis) and that (2) plants with desiccation-tolerant (DT), i.e. orthodox, seeds exhibited greater survivorship than plants with desiccationsensitive (DS), also known as recalcitrant, seeds. Late embryogenesis abundant (LEA) protein gene families are perceived to confer DT and seed longevity among vascular plants. Non-parametric Wilcoxon signed-rank test for matched pairs and a Mann-Whitney U test reveal that plant lineages perceived to have undergone WGD across the KPB exhibit significantly greater numbers of LEA genes than those that did not. On the basis of these data, this investigation elicits a merger between the KPB-WGD and KPB-seed traits concepts. However, emphasis is shifted from the concept of WGD as an immediate adaptation to climatic stress at the KPB (the KPB-WGD hypothesis) to the concept that WGD was an exaptation, which, by definition, fortuitously enhanced the survival of vascular plants across the KPB but that probably evolved initially in other climatic contexts.

Sauropterygia was a taxonomically and ecomorphologically diverse clade of Mesozoic marine reptiles spanning the Early Triassic to the Late Cretaceous. Sauropterygians are traditionally divided into two groups representing two markedly different body plans – the short-necked, durophagous Placodontia and the long-necked Eosauropterygia – whereas Saurosphargidae, a small clade of armoured marine reptiles, is generally considered as the sauropterygian sister-group. However, the early evolutionary history of sauropterygians and their phylogenetic relationships with other groups within Diapsida are still incompletely understood. Here, we report a new saurosphargid from the Early Triassic (Olenekian) of South China – Prosaurosphargis yingzishanensis gen. et sp. nov. – representing the earliest known occurrence of the clade. An updated phylogenetic analysis focussing on the interrelationships among diapsid reptiles recovers saurosphargids as nested within sauropterygians, forming a clade with eosauropterygians to the exclusion of placodonts. Furthermore, a clade comprising Eusaurosphargis and Palatodonta is recovered as the sauropterygian sister-group within Sauropterygomorpha tax. nov. The phylogenetic position of several Early and Middle Triassic sauropterygians of previously uncertain phylogenetic affinity, such as Atopodentatus, Hanosaurus, Majiashanosaurus, and Corosaurus, is also clarified, elucidating the early evolutionary assembly of the sauropterygian body plan. Finally, our phylogenetic analysis supports the placement of Testudines and Archosauromorpha within Archelosauria, a result strongly corroborated by molecular data, but only recently recovered in a phylogenetic analysis using a morphology-only dataset. Our study provides evidence for the rapid diversification of sauropterygians in the aftermath of the Permo-Triassic mass extinction event and emphasises the importance of broad taxonomic sampling in reconstructing phylogenetic relationships among extinct taxa.