Evolution Diary

The largest extinction in Earth’s history not only wiped out 95 percent of sea creatures and 70 percent of land animals, it also gave the oceans a fundamental “face lift,” according to a new study.

Before the end-Permian mass extinction 250 million years ago, the seas were home to a balance of both ecologically simple communities and complex ones. Following the extinction, complex communities displaced simple ones, coming to outnumber them three-to-one, a pattern that prevails today.

It reflects the current dominance of complex, mobile organisms, such as snails and crabs, and the decreased diversity of simple, stationary organisms such as sea lilies, which filter nutrients from the water.

Continue reading