Triassic–Jurassic environmental instability on the subtropical eastern Tethyan margin linked to the dinosaur occurrence

The Triassic–Jurassic transition marks a critical interval, witnessing major biotic turnovers, including the rise of dinosaurs and the end-Triassic mass extinction (ETME), triggered by the Central Atlantic Magmatic Province (CAMP). 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 CAMP environmental impacts on this subtropical terrestrial setting and placement of the Triassic–Jurassic boundary (TJB). Critically, the earliest regional sauropodomorph fossils occurred at ~ 200.17 Ma (~ 1.23 Myr post-TJB), indicating post-ETME colonization in low paleolatitudes by medium- to large-bodied dinosaurs. CAMP-induced stressors, potentially coupled with increased climate seasonality, likely created ecological opportunities facilitating dinosaur expansion in the Earliest Jurassic.