| details |
Late Llandeilian |
Caradocian |
USSR(Estonian SSR) |
Uutela,A. et al. Ordovician acritarchs from the Rapla borehole, Estonia |
1991 |
| original |
Late Llanvirnian |
|
USSR(Estonian SSR) |
Uutela,A. et al. Ordovician acritarchs from the Rapla borehole, Estonia |
1991 |
| details |
Middle Ordovician |
|
USSR(Estonian SSR) |
Sarjeant,W.A.S. et al. The Micrhystridium and Veryhachium Complexes (Acritarcha: Acanthomorphitae and Polygonomorphitae): A taxonomic reconsideration. |
1994 |
| details |
Early Caradocian |
|
Sweden |
Wallin,A. et al. Biostratigraphical investigation of Middle Ordovician acritarch the post-impact sequence in the Tvaren-2 core, Sweden. |
1996 |