SHROUDED by foliage and separated from the city by the Hudson River, the looming cliffs of the Palisades mean little more to most New Yorkers than a pleasant view from the West Side Highway. But these titanic ramparts of ancient basalt are also monuments to an apocalypse.

The cliffs were once underground channels of molten rock that fed widespread volcanic eruptions 200 million years ago as the supercontinent Pangaea pulled apart at the seams. The eruptions covered more than four million square miles with basalt lava and belched vast amounts of carbon dioxide and sulfur into the atmosphere. Brief volcanic winters followed, but the eruptions also set off an ocean-acidifying, global-warming catastrophe that wiped out three-quarters of life on earth. This was the end-Triassic extinction, which cleared the way for the dinosaurs and their domination of the planet for the next 136 million years, before a giant asteroid struck Mexico and ended their reign.

This spring, a team of researchers from Columbia University and the Massachusetts Institute of Technology published a paper in the journal Science connecting these eruptions — which took place in four pulses over 600,000 years — with this global near-death experience, one of five major extinctions over the last 540 million years.

Paul E. Olsen, a paleontologist at Columbia and one of the study’s co-authors, recently took me on a tour of the Palisades. Before we left, he showed me a fossil that he and his 12-year-old son found on a beach in Haverstraw, N.Y., along the Hudson — the imprint of a clumsy-looking five-knuckled foot. It was made by a species of crocodilian reptile, a rauisuchian, the dominant predator before the volcanic cataclysm.