Cyathosphaera cruciformis Hay & Towe, 1962
Cruciplacolithus zachosii Bernaola & Monechi, 2007
Bernaola, G. & Monechi, S., (2007): Calcareous nannofossil extinction and survivorship across the Cretaceous_Paleogene boundary at Walvis Ridge (ODP Hole 1262C, South Atlantic Ocean). - Palaeogeography Palaeoclimatology Palaeoecology. 255: 132-156.
Hay, W. W. & Towe, K. M., (1962): Electron microscope examination of some coccoliths from Donzacq (France). - Eclogae Geologicae Helvetiae. 55: 497-517.
Roth, P. H., (1970): Oligocene calcareous nannoplankton biostratigraphy. - Eclogae Geologicae Helvetiae. 63: 799-881.
Cyathosphaera cruciformis
Hay & Towe, 1962
Middle Eocene
Tuilerie de Donzacq, Landes, France