| original |
Late Ordovician |
|
Indiana |
Tappan,H. et al. Surface sculpture of the wall in Lower Paleozoic acritarchs. |
1971 |
| details |
Middle Ordovician |
|
Sweden |
GŠ³rka,H. Middle Ordovician (Viruan) acritarchs and Prasinophyceae from the Smedsby Gard No.1 borehole in (Gotland, Sweden). |
1987 |
| details |
Nd |
|
Nd |
Fensome,R.A. et al. Acritarchs and Fossil Prasinophytes: An index to genera, species and infraspecific taxa. |
1990 |
| details |
Ordovician |
|
Nd |
Servais,T. An annotated bibliographical review of Ordovician acritarchs |
1997 |