Scientists finally solved the mystery of Earth's greatest mass extinction

Why do beaches today have seashells from clams and snails instead of brachiopods? A new study suggests the answer lies in Earth's greatest mass extinction, when warming oceans and falling oxygen levels wiped out animals that couldn't adapt. Species with body plans and metabolisms better suited to the changing conditions survived and went on to dominate the seas, offering a glimpse of how modern marine life could respond to climate change.