The Carnian Pluvial Episode — 234 to 232 million years ago, Late Triassic — sits awkwardly between mass extinction and ecological reorganization. It killed groups of organisms while simultaneously enabling the diversification of dinosaurs, modern conifers, and other lineages that would dominate the Mesozoic.
Palynological analysis of sediments from the Jiyuan Basin in China identifies four discrete phases of terrestrial vegetation transition during this episode. Each vegetation shift is temporally correlated with geochemical indicators of volcanic activity. Not one event, but four pulses.
The plant fossil record here acts as a seismograph for deep-time volcanism. Each pollen assemblage shift — a change in which plants dominate the landscape — is a proxy for an eruption sequence that is otherwise invisible in the rock record. The volcanic deposits themselves may be eroded or altered beyond recognition, but the vegetation response is preserved in pollen grains that survive for hundreds of millions of years.
The four-pulse structure reframes the Carnian Pluvial Episode from a single catastrophe to a serial perturbation. The ecosystem didn't collapse once and rebuild. It was hit, partially recovered, hit again, partially recovered, hit a third time, and a fourth. Each recovery was incomplete, and each subsequent pulse pushed the ecosystem further from its original state. By the fourth pulse, the recovery trajectory had diverged enough that entirely new lineages — including the earliest dinosaurs — found ecological space that hadn't existed before.
The through-claim: a single perturbation creates a disaster. A series of perturbations with incomplete recovery between them creates an evolutionary opportunity. The innovation emerges not from the destruction but from the inability to fully rebuild before the next hit — the incomplete recovery is the opening.