Anomalies of sulfur compound-specific molecular fossils link terrestrial ecosystem collapse to the end-Triassic crisis

The end-Triassic mass extinction (ETE), one of the “Big Five” in Earth history, was triggered by Central Atlantic Magmatic Province (CAMP) volcanism, releasing voluminous CO₂, SO₂ and halocarbons, which affected global marine and terrestrial ecosystems through atmospheric circulations. The terrestrial ecosystem collapse is commonly attributed to CO₂-drivengreenhouse effects changing climates that consequently impacted flora and fauna, but this fails to explain why atmospheric CO₂ with long retention timejust dominates a range of short-lived crises. Here, we investigate two terrestrial Triassic-Jurassic sections in each high- and low/middle- paleolatitude, finding anomalies of sulfur-associated molecular fossils, biomarker proxies of “high-temperature wildfires” and higher plants burial. These coincide with relatively short CAMP climax (lasting ~ 60,000 years). We propose a novel hypothesis that the high-intensity pulses of acid rains originated from CAMP climax dominated catastrophic defoliation, which oversupply dead moisture-free biomass as fuels in unusual rates, leaving coeval widespread abnormally high-temperature wildfires and spikes of sulfur compound-specific molecules in terrestrial sediments as fingerprints of acid rain deposition.