This is a because 541 million years ago with the Cambrian explosion, an extraordinary diversification of marine animals, and ended about 252 million years ago
Paleozoic Era, also spelled Palaeozoic, major interval of geologic time that began 541 million years ago with the Cambrian explosion, an extraordinary diversification of marine animals, and ended about 252 million years ago with the end-Permian extinction, the greatest extinction event in Earth history.
