A new study finds plant-eating dinosaurs arrived in the Northern Hemisphere millions of years after their meat-eating cousins. And scientists think they know the reason: climate change. It was brutally hot and dry 230 million years ago with two desert belts above and below the equator. That made it hard for plants to survive in the deserts. So the plant-eating dinosaurs couldn’t get through while meat-eating dinosaurs could by feasting on insects. Scientists think that only when carbon dioxide levels fell a bit did the climate change just enough so the plants could grow in these regions — and the plant eaters could move out of South America.
