Hierarchy classification:

1. top of the aat hierarchies
2. Styles and Periods Facet
3. Styles and Periods (hierarchy name)
4. [styles, periods, and cultures by general era]
5. geologic time scale
6. Phanerozoic
7. Paleozoic

Anotations

Scope note:

The earliest period of the Paelozoic, extending from about 542 to 488 million years ago. It is characterized by rapid diversification of marine life. Cambrian rocks are the first to contain an abundance of fossils.