Genus Tetrads
- Species total:
- 3
- Age range:
- 490 - 395 MA (obsolete dating)
- IRMNG:
- find
| Name | From | To | Age range |
|---|---|---|---|
| Tetrads sp | Arenigian | Ludfordian |
|
| Tetrads sp. Rich.,1988 | Ashgillian | Ashgillian |
|
| Tetrads sp. Stee.et al,2000 | Nd | Nd |
|