BBC: Immense volcanic activity helped the dinosaurs rise to prominence some 200 million years ago, a study suggests. Dinosaurs were the dominant vertebrates on land for some 135 million years. While it is widely accepted that an asteroid or comet wiped them out, there has been less agreement on the factors which led to their ascendancy. Research in PNAS journal suggests volcanic eruptions changed the climate, causing a mass extinction that wiped out the dinosaurs’ main …