| original |
Desmoinesian |
Virgilian |
Illinois |
Stidd,B.M. et al. Callandrium callistophytoides, gen.et sp.nov., the probable pollen-bearing organ of the seed fern, Callistophyton |
1970 |
| details |
Late Pennsylvanian |
|
Illinois |
Hall,J.W. et al. Ontogeny of Vesicaspora, a Late Pennsylvanian pollen grain. |
1971 |
| details |
Middle Pennsylvanian |
Late Pennsylvanian |
Illinois |
Rothwell,G.W. Pollen grains of the Pennsylvanian Callisto Phytaceae (Pteridospermopsida) |
1972 |
| details |
Late Pennsylvanian |
|
Illinois |
Millay,M.A. et al. Microgametophyte development in the Paleozoic seed fern Family Callistophytaceae. |
1974 |
| details |
Carboniferous |
|
USA |
Balme,B.E. Fossil in situ, spores and pollen grains: An annotated catalogue. |
1995 |