| original |
Ashgillian |
|
Oklahoma |
Loeblich,A.R.,Jr. et al. Some Middle and Late Ordovician microphytoplankton from Central North America. |
1978 |
| details |
Middle Ordovician |
|
Sweden |
GŠ³rka,H. Middle Ordovician (Viruan) acritarchs and Prasinophyceae from the Smedsby Gard No.1 borehole in (Gotland, Sweden). |
1987 |
| details |
Ashgillian |
|
Nd |
Fensome,R.A. et al. Acritarchs and Fossil Prasinophytes: An index to genera, species and infraspecific taxa. |
1990 |
| details |
Arenigian |
Ashgillian |
China(Hupei) |
Tongiorgi,M. et al. Arenigian acritarchs from the Daping section (Yangtze Gorges area, Hubei Province, southern China) and their palaeogeographic significance. |
1995 |