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.