Biology subjects

Foster, W. J.

Publications and source records attributed to Foster, W. J..

6 recordsLinked to original sources

bioRxiv2026

Borealization: a biodiversity refugium and evolutionary cradle during the Permian-Triassic climate crisis

Understanding how organisms track suitable environments during rapid climate change is constrained by the brevity of modern observations. Using the fossil record, we identify the mid- to high-latitude Boreal Ocean as a regional biodiversity refugium during the Permian-Triassic climate crisis. Additional Boreal successions indicate sustained diversity and comparatively hospitable conditions. Biogeographic reconstructions reveal that 30% of Sassendalen taxa survived the extinction event, with two-thirds expanding or shifting their latitudinal ranges into the Boreal Ocean. More than 90% of newly evolved species originated there, and their lineages subsequently dispersed at differing rates into other regions throughout the Early Triassic. These findings identify poleward migration and high-latitude refugia as key drivers of biodiversity persistence and evolutionary recovery during climate crises.

ecology↗

bioRxiv2026

Temporal resolution reshapes dynamics of inferred community structure and extinction selectivity across the Permian-Triassic mass extinction

The Permian-Triassic mass extinction fundamentally restructured ecosystems, yet it remains unresolved whether ecological collapse unfolded gradually or in discrete steps, and how extinction selectivity varied with environmental change. Here, we analyse marine food webs from Meishan (China) at high temporal resolution. We show that trophic structure destabilised prior to peak biodiversity loss, followed by a structural tipping point during the extinction interval when the community became less robust to secondary extinctions. Extinction selectivity shifted substantially across the study interval. During the extinction interval, extinction was concentrated at lower trophic levels, propagating upwards from benthic herbivores to higher-level consumers. Although coarse resolution preserves temporal trends in trophic structure and extinction selectivity, it obscures abrupt transitions, sequential extinction dynamics, and critical shifts in ecological organisation. We demonstrate that temporal resolution governs inference of extinction dynamics, with important implications for reconstructing past ecological crises and interpreting ecosystem responses to rapid environmental change.

paleontology↗

bioRxiv2025

New insights into the extinction and recovery of marine vertebrates across the Permian-Triassic mass extinction event in the Dolomites, Southern Alps, Italy

The impact of the Permian-Triassic mass extinction on marine vertebrates is poorly known due to their scarce fossil record. Here, we report Acrodus sp. [Chondrichthyes], Bobasatrania aff. ladina [Osteichthyes] and an indeterminate actinopterygian from the Changhsingian Bellerophon Formation, and a saurosphargid reptile from the lower Spathian Val Badia Member of the Werfen Formation in the Dolomites, Italy. The saurosphargid is represented by a single vertebra, whose relatively tall neural spine indicates that it might belong to a new species. This is one of the oldest Sauropterygomorpha records worldwide and the first unambiguous occurrence of Saurosphargidae in the western Paleo-Tethys during the Early Triassic. These new findings suggest fishes were more diverse in this paleo-tropical shallow shelf community of the western Paleo-Tethys in the latest Permian than during the Early Triassic. The evolution of the new apex predator niche (Saurosphargidae) relatively shortly after the mass extinction event coincides with the reappearance of predatory cephalopods and precedes the full ecological and taxonomic recovery of benthic groups in the Dolomites community. This contrasts with previous hypotheses about the delayed recovery of higher trophic groups. Furthermore, we dated a surface sample with actinopterygian scales found at a Permian-Triassic boundary outcrop. The U-Pb indicates 248+/-1 Ma as a maximum depositional age, and radiolarian biostratigraphy indicates an Anisian age. This suggests age assignments to surface samples require caution. U-Pb dating further reveals an age discrepancy in the scales and the host rock, likely due to 206Pb enrichment in scales during diagenesis.

paleontology↗

bioRxiv2023

Thermal and Nutrient Stress Drove Permian-Triassic Marine Extinctions

The Permian-Triassic mass extinction coincides with extensive environmental changes (i.e., thermal stress, deoxygenation and potentially ocean acidification), but the primary drivers of extinction in them marine realm are currently unknown. To understand which factors caused extinctions, we quantitatively investigated the relationship between geochemical proxies and fossil record at the most intensively-studied locality for this event, the Meishan section, China. We found that {delta}18Oapatite (paleotemperature proxy) and {delta}114Cd (primary productivity proxy) best explain changes in species diversity and composition at Meishans paleoequatorial setting. These findings suggest that the physiological stresses induced by ocean warming and nutrient availability 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. One-Sentence SummaryOcean warming and nutrient availability were key drivers of equatorial marine extinctions during the Permian-Triassic mass extinction.

evolutionary biology↗

bioRxiv2023

Response of siliceous marine organisms to the Permian-Triassic climate crisis based on new findings from central Spitsbergen, Svalbard

Siliceous marine ecosystems play a critical role on the Earths climate system through its influence on organic carbon burial and rates of marine authigenic clay formation (i.e. reverse weathering). The ecological demise of silicifying organisms associated with the Permian-Triassic mass extinction is postulated to have elevated rates of marine authigenic clay formation, resulting in a prolonged greenhouse climate during the Early Triassic. Yet, our understanding of the response of siliceous marine organisms during this critical interval is poor. Whilst radiolarians experienced the strongest diversity loss in their evolutionary history and perhaps also the greatest population decline of silica-secreting organisms during this event, only a small number of Griesbachian (post-extinction) localities that record siliceous organisms are known. Here, we report newly discovered latest Changhsingian to early Griesbachian (Clarkina meishanensis - Hindeodus parvus Zone) radiolarians and siliceous sponge spicules from Svalbard. This fauna documents the survival of a low-diversity radiolarian assemblage alongside stem-group hexactinellid sponges making this the first described account of post-extinction silica-secreting organisms from the Permian/Triassic boundary in a shallow marine shelf environment and a mid-northern palaeolatitudinal setting. Our findings indicate that latitudinal diversity gradients for silica-secreting organisms following the mass extinction were significantly altered, and that silica productivity was restricted to high latitude and deep water thermal refugia. This result has potential to further shape our understanding of changes to marine porewater and seawater dissolved silica levels and in turn rates of reverse weathering, with implications for our understanding of carbon cycle dynamics during this interval. This also suggests that the export of organic carbon to the deep ocean was not as severely impacted at non-equatorial latitudes. Key PointsO_LIWe document the first occurrence of siliceous sponge spicules and radiolarians (biogenic silica) from a mid-northern paleolatitude following the mass extinction event C_LIO_LIHoldover radiolarian species show poleward range shifts C_LIO_LIThe ecological composition and the restriction to shallow water oxygenated facies suggests a shallow mid-latitude refuge for siliceous marine organisms C_LIO_LIThis result has potential to further shape our understanding of changes to marine dissolved silica levels and in turn rates of reverse weathering, with implications for our understanding of Permian-Triassic carbon cycle dynamics. C_LI

evolutionary biology↗

bioRxiv2020

Machine learning (decision tree analysis) identifies ecological selectivity patterns across the end-Permian mass extinction

Decision tree algorithms are rarely utilized in paleontological research, and here we show that machine learning algorithms can be used to identify determinants of extinction as well as predict extinction risk. This application of decision tree algorithms is important because the ecological selectivity of mass extinctions can reveal critical information on organismic traits as key determinants of extinction and hence the causes of extinction. To understand which factors led to the mass extinction of life during an extreme global warming event, we quantified the ecological selectivity of marine extinctions in the well-studied South China region during the end-Permian mass extinction using the categorized gradient boosting algorithm. We find that extinction selectivity varies between different groups of organisms and that a synergy of multiple environmental stressors best explains the overall end-Permian extinction selectivity pattern. Extinction risk was greater for genera that were limited to deep-water habitats, had a stationary mode of life, possessed a siliceous skeleton or, less critically, had calcitic skeletons. These selective losses directly link the extinction to the environmental effects of rapid injections of carbon dioxide into the ocean-atmosphere system, specifically the combined effects of expanded oxygen minimum zones, rapid warming, and ocean acidification.

evolutionary biology↗