The greatest mass extinction in Earth's history also may have been one of the slowest, according to a study that casts further doubt on the extinction-by-meteor theory.
Creeping environmental stress fueled by volcanic eruptions and global warming was the likely cause of the Great Dying 250 million years ago, said USC doctoral student Catherine Powers.
So what caused the increased volcanic action? They never say. Could it have been triggered by a meteor? They never say one way or the other. Maybe plate tectonics?