About 252 million years ago, the largest extinction known occurred at the end of the Permian Period. Why? a Volcanic eruptions released CO2 that heated the planet greatly, and the oceans released poison gas b The CO2 released by early humans barbecuing dinosaurs warmed the planet too much c Dinosaurs suffered unfortunate gastric emissions that raised the Earth's temperature d The ice ages began, and the cold froze the dinosaurs and other species e A meteorite kicked up dust that blocked the sun and froze the planet
