Triassic–Jurassic environmental instability on the subtropical eastern Tethyan margin linked to low-latitude dinosaur dispersal

The Triassic–Jurassic transition marks a critical interval, witnessing major biotic turnovers, including the rise of dinosaurs and the end-Triassic mass extinction, triggered by the Central Atlantic Magmatic Province. However, the volcanism linked to terrestrial ecosystem disturbance and dinosaur distribution remains poorly constrained. Here we present an integrated dataset of chemostratigraphic and astrochronological records for a continental drill core from the Kunming Basin in Yunnan Province of Southwest China, where rich dinosaur assemblages have been previously identified. Three negative carbon isotope excursions coupled with volcanogenic mercury anomalies confirm pulsed volcanism-induced environmental impacts on this subtropical terrestrial setting and placement of the Triassic–Jurassic boundary. Critically, the earliest regional sauropodomorph fossils occurred at ~200.17 Ma, indicating post-extinction colonization in low palaeolatitudes by medium- to large-bodied dinosaurs. Large-scale volcanism-induced stressors, potentially coupled with increased climate seasonality, likely created ecological opportunities facilitating dinosaur expansion in the earliest Jurassic. Early regional sauropodomorph fossils from 200.17 Ma suggest post-Triassic mass extinction dinosaur colonization in low paleolatitudes, likely due to Central Atlantic Magmatic Province stressors and increased climate seasonality, according to chemostratigraphic and astrochronological analysis of a core from the Kunming Basin in China.