Shu-Zhong Shen

The Permian-Triassic transition (∼252 million years ago) marks the most severe mass extinction in Earth’s history, followed by a protracted interval of environmental instability and delayed biological recovery. Although elevated atmospheric carbon dioxide (CO ₂ ) from extensive volcanism is widely invoked, the role of continental weathering feedbacks in regulating global climate has not been effectively constrained. Here, we present high-resolution lithium isotope records from marine carbonates and terrestrial deposits through the Permian-Triassic transition. Combined with an Earth-system model, our data reveal notable decreases in global continental weatherability following the end-Permian mass extinction, inferred to associations with widespread deforestation (extinction of deep-rooted plants) and the collapse of terrestrial ecosystem. This diminished weathering response to volcanic carbon emissions likely contributed to prolonged high atmospheric CO ₂ and global temperature during the Early Triassic. The sustained greenhouse conditions, in turn, inhibited contemporaneous marine and terrestrial ecosystem recoveries. Our findings highlight the importance of terrestrial ecosystem in modulating global carbon cycle stability, and its effects on Earth’s habitability.

The late Neoproterozoic–early Paleozoic (~600 to 520 million years ago) witnessed a fundamental shift under atmosphere-ocean redox conditions, where pulsed ocean oxygenation events (OOEs) were replaced by episodic ocean anoxic events (OAEs). The Cambrian Steptoean positive carbon isotope excursion (SPICE) event (494.5 to 492.5 million years ago) represents a major early Paleozoic OAE, yet its drivers and underlying dynamics remain controversial. Here, we present carbonate uranium isotope (δ ²³⁸ U _carb ) data from North and South China, revealing a sharp decrease from −0.29 ± 0.12 per mil to −0.85 ± 0.03 per mil at the onset of the SPICE event, followed by a return to pre-excursion values. This indicates a rapid onset of global ocean anoxia before the rise of δ ¹³ C _carb values, followed by a transition to oxic conditions. Integrating δ ²³⁸ U _carb data with refined COPSE (Carbon, Oxygen, Phosphorus, Sulphur, and Evolution) biogeochemical modeling reconciles the pre-SPICE redox paradox of low atmospheric p O ₂ coexisting with limited seafloor anoxia. We propose that the SPICE and its associated excursions reflect a non-steady-state Earth system behavior, involving oscillations in coupled phosphorus-oxygen-carbon-sulfur and uranium cycles, which influenced the evolution of early animals through redox-dependent biodiversity filters.

The Eocene–Oligocene transition was the crucial turning point when Earth’s climate shifted to its current icehouse state. Understanding how the marine biosphere responded during this transition is not well-constrained, appearing as a simple extinction pulse in low temporal resolution global compendia. Here we design an artificial-intelligence-inspired metaheuristics algorithm to construct a high-resolution global species richness history across the Eocene–Oligocene transition for the rich foraminifera fossil record with an imputed ~29,000-year resolution. The revealed diversity dynamics are complex and differ for each foraminiferal group with distinct ecology. Planktonic and shallow-water larger benthic foraminifera show steady diversity levels in the early phases of the transition in the latest Eocene after a long-term reduction, while the deeper-water small benthic foraminifera radiate notably and then decline over the same interval. In the earliest Oligocene, the planktonic and larger foraminifera suffer major species losses coincident with the first continental-scale ice sheet formed on Antarctica, while small benthic foraminifera diversity holds steady, followed by an accelerating lowering as the early Oligocene proceeds. These findings reveal complicated and ecologically differentiated environment-life processes, indicating the importance of high-resolution temporal data for dissecting out ecological responses to major environmental changes.

High-resolution geomagnetic record at the end Permian is essential for probing the Earth’s core dynamics, stratigraphic dating, correlation of continental strata with marine ones, as well as linkage between biosphere variation and geomagnetic field. Here, we report a high-resolution geomagnetic polarity sequence across the Permian Guadalupian-Lopingian boundary (GLB, ~260 million year) from South China. This record reveals an episode of exceptionally high polarity reversal rate. Notably, fluctuations in the geomagnetic polarity reversal coincide with major global changes - including Pangea configuration shift, widespread volcanism, and Paleozoic sea-level lowstand and biodiversity perturbations. Cross-correlations indicate that moderate environmental stress may enhance biodiversity, whereas exceeding tolerance thresholds drives the biodiversity declines and potential extinction events. These findings highlight that geodynamic forcing as an essential control on the long-term stability and habitability of biosphere.

The Late Palaeozoic Ice Age (LPIA), was one of Earth's most extensive and long-lasting glacial episodes, spanning roughly from 350 to 260 Ma. The Arabian Peninsula is long known to have experienced the LPIA at its position at the northern edge of Gondwana throughout the Late Carboniferous (Pennsylvanian) to the Early Permian (Cisuralian) and particularly the deglaciation that occurred from the latest Gzhelian, through late Sakmarian/early Artinskian to mid-Kungurian. Modelling of Mean Annual Surface Temperature (MAST; Li et al. 2022) for this period superimposed on palaeogeographic maps based on PaleoDEM and points/polyline/polygon (rotation and geometry files) of Scotese and Wright (2018) allows temperature-calibration of the succession of palynological assemblages. A number of trends and generalisations are possible related to MAST change between -0.2°C to -3.4°C (latest Gzhelian) and 9.3°C to 11.1°C (mid-Kungurian). As a group, the plants that produced monosaccate pollen (now extinct) appear amongst the most tolerant of MAST increase, with certain genera, for example Plicatipollenites and Cannanoropollis, being common throughout. Punctatisporites probably produced by the simplest most cold-adapted plants such as mosses were the most sensitive to climate warming. Cingulicamerate spores and fern spores of Microbaculispora and Horriditriletes are similarly sensitive to warming conditions particularly as MAST reaches above 0°C. MAST above 0°C appears to have stimulated a surge of caytonialean-type, probably upland, trees or shrubs that produced Pteruchipollenites indarraensis, although continued warming seems to have been at least partly responsible for restricting their distribution because such plants are almost absent at 208 Ma where MAST is ~10°C. Kingiacolpites subcircularis, probably produced by a cycad, may, also have been stimulated by MAST reaching above 0°C. Some of these trends in palaeovegetation in response to climate warming may have relevance in studies of modern environmental change.

The Silurian Period was a pivotal interval of biotic innovation and tectonic activity. In South China, Silurian strata host exceptional fossil assemblages, including some of the world’s earliest jawed vertebrates (gnathostomes), alongside a record of the regional Yangtze uplift. However, the timing and tempo of these key evolutionary and tectonic events remain poorly constrained due to a lack of precise radioisotopic ages and limitations of biostratigraphic correlation in shallow-marine clastic facies. This study provides a robust temporal framework for these events through high-precision U-Pb geochronology of zircons from three volcanic tuff beds within the Silurian Xiushan Formation of the Upper Yangtze region, analyzed using the chemical abrasion−isotope dilution−thermal ionization mass spectrometry method. Our new ages of 433.93 ± 0.52 Ma, 432.92 ± 0.54 Ma, and 430.68 ± 0.62 Ma (2σ total uncertainty), along with Bayesian age-stratigraphic modeling, anchor the deposition of the fossiliferous upper Xiushan Formation to the Telychian-Sheinwoodian boundary interval (latest Telychian). This absolute age framework refines the equivocal early Telychian age estimate for the formation based on previous biostratigraphic interpretations. The new geochronology recalibrates the timeline of early gnathostome evolution by placing the renowned Chongqing Lagerstätte and its diverse fauna within the Wenlock. This discovery helps to resolve the apparent “anachronism” of such complex faunas appearing in older strata, demonstrating that a major radiation of jawed vertebrates was well underway by the Wenlock—reshaping our understanding of one of the most critical Paleozoic evolutionary transitions. A major regional unconformity immediately overlying our 430.68 ± 0.62 Ma tuff indicates that the terminal marine sedimentation preceding large-scale regression in response to the Yangtze uplift extended into the latest Sheinwoodian in the Yangtze Platform interior. This recalibration shifts the onset of the Yangtze uplift by at least 4 m.y., refining models of intraplate orogenesis in East Asia.