consider the disruption inflicted on the planet by the rise of land plants more than 300 million years earlier. In the Paleozoic, land plants conquered the continents and geoengineered the planet, possibly contributing to, or even causing, at least 10 extinction pulses over 25 million years, including one of the worst mass extinctions in Earth history. Land plants profoundly and permanently altered Earth’s geochemical cycles, underwrote the flourishing of all subsequent life on land, and might have sequestered so much carbon dioxide that they kicked off a 90-million-year ice age.