Brachiopods, molluscs and echinoderms
The familiar shelled inhabitants of the Paleozoic seafloor all appear within a few million years.
- When
- Known to
- ± 5 million years
- Era
- Cambrian, Paleozoic
Brachiopods — two-shelled filter feeders superficially like clams — radiate rapidly and become the dominant shelled animals of Paleozoic seas, far outnumbering bivalves for the next 250 million years. Molluscs and the first echinoderms, including bizarre asymmetric forms with no living counterpart, appear in the same interval. Between them these groups establish the basic ecology of the seafloor.