| details |
Middle Ordovician |
Late Ordovician |
Iran |
Ghavidel-Syooki,M. Chitinozoan biostratigraphy and palaeogeography of Late Ordovician and Early Silurian strata at southwestern Bojnurd City in eastern Alborz Mountain Ranges (Kopet Dagh Region), Southeastern Caspian Sea. |
1998 |
| details |
Late Ordovician |
|
Nevada |
Finney,S.C. et al. Late Ordovician mass extinction: A new perspective from stratigraphic sections in Central Nevada. |
1999 |
| details |
Gamachian |
|
Canada(Anticosti Island) |
Soufiane,A. et al. Chitinozoan zonation of the Late Ordovician and the Early Silurian of the island of Anticosti, Quebec, Canada. |
2000 |