| original |
Llanvirnian |
Caradocian |
Poland |
Gгrka,H. The Middle Ordovician acritarchs of Olsztyn IG2, (Poland). |
1979 |
| details |
Middle Ordovician |
|
Sweden |
Gгrka,H. Middle Ordovician (Viruan) acritarchs and Prasinophyceae from the Smedsby Gard No.1 borehole in (Gotland, Sweden). |
1987 |
| details |
Llandeilian |
|
Nd |
Fensome,R.A. et al. Acritarchs and Fossil Prasinophytes: An index to genera, species and infraspecific taxa. |
1990 |
| details |
Late Llanvirnian |
Ashgillian |
USSR(Estonian SSR) |
Uutela,A. et al. Ordovician acritarchs from the Rapla borehole, Estonia |
1991 |