| original |
Middle Ordovician |
|
Finland |
Tynni,R. Ordovician hystrichospheres and chitinozoans in limestone from the Bothnian Sea. |
1975 |
| details |
Late Ordovician |
|
Sweden |
Eiserhardt,K.H. Baltisphaerid of the –jlemyrflint of Gotland, Sweden (Acritarchs of the Upper Ordovician boulders). |
1989 |
| details |
Middle Ordovician |
|
Nd |
Fensome,R.A. et al. Acritarchs and Fossil Prasinophytes: An index to genera, species and infraspecific taxa. |
1990 |
| details |
Late Caradocian |
|
USSR(Estonian SSR) |
Uutela,A. et al. Ordovician acritarchs from the Rapla borehole, Estonia |
1991 |