Sphenolithus runus Bown & Dunkley Jones, 2006
The apical spine of Sphenolithus runus has parallel extinction (extinction angle is 0°) whereas the apical spine of Sphenolithus strigosus has an inclined extinction (extinction angle at 45°). The apical spines of Furcatolithus obtusus have oblique extinction (extinction angle is about 22°).
Bown, P. R., Dunkley Jones, T., 2006. New Paleogene calcareous nannofossil taxa from coastal Tanzania: Tanzania Drilling Project Sites 11 to 14. Journal of Nannoplankton Research 28(1), 17-34.
Bown & Dunkley Jones, 2006
TDP Site 13, Pande, Tanzania