The first corals
Tabulate and rugose corals appear and begin building reefs that will define Paleozoic seas.
- When
- Known to
- ± 5 million years
- Era
- Ordovician, Paleozoic
Two coral groups with no living descendants — tabulate corals forming honeycomb colonies, and solitary horn-shaped rugose corals — appear in the Early Ordovician. Together with stromatoporoid sponges and bryozoans they construct the first large reef systems since the archaeocyaths died out. These reefs are the dominant shallow-marine ecosystem for the next 250 million years, until both groups are wiped out at the end of the Permian.