Set number: 849

  • Furcatolithus peartiae 159 1
  • Furcatolithus peartiae 160 2
  • Furcatolithus peartiae 162 3
  • Furcatolithus peartiae 161 4
Furcatolithus peartiae, Early Oligocene, DSDP Leg 25, Site 242, Mozambique Channel (Davie Ridge), Indian Ocean
Final Epithet
Furcatolithus peartiae (Bown & Dunkley Jones, 2012) Howe, 2021

Sphenolithus peartiae Bown & Dunkley Jones, 2012


Sphenolithus tawfikii Bergen & de Kaenel in Bergen et al., 2017


Species of Furcatolithus have a relatively high hollow cylindrical proximal cycle and a long duolithic conical apical spine with or without bifurcation. The apical spine is triangular in the axial section. In cross-polarised light, the apical spine with axial c-axis shows maximum birefringence at 45° but extinct (dim) at 0° [the axial suture between the two helves is better seen at this orientation].

The other side of the hallow cylindrical proximal cycle is better seen at 45° and displays the axial c-axis.


Furcatolithus peartiae differs from Furcatolithus celsus (Haq, 1971) Howe, 2021 and Furcatolithus predistentus (Bramlette & Wilcoxon, 1967) Howe, 2021 by having a distinctly higher proximal cycle. The diameter of the proximal cycles is distinctly less than the diameter of the base of the apical spine in Furcatolithus predistentus. Moreover, Furcatolithus predistentus have a broadening at the bottom of its apical spine.


Bergen, J. A., de Kaenel, E., Blair, S. A., Boesiger, T. M., Browning, E., 2017. Oligocene-Pliocene taxonomy and stratigraphy of the genus Sphenolithus in the circum North Atlantic Basin: Gulf of Mexico and ODP Leg 154. Journal of Nannoplankton Research 37(2-3), 77-112.

Bown, P. R., Dunkley Jones, T., 2012. Calcareous nannofossils from the Paleogene equatorial Pacific (IODP Expedition 320 Sites U1331-1334). Journal of Nannoplankton Research 32(2), 3-51.

Howe, R., 2021. Ultrastructure and taxonomy of the family Sphenolithaceae. Journal of Nannoplankton Research 39(1), 29-75.

Bramlette, M. N., Wilcoxon, J. A., 1967. Middle Tertiary calcareous nannoplankton of the Cipero section, Trinidad, W.I. Tulane Studies in Geology and Paleontology 5, 93-131.

Haq, B. U., 1971. Paleogene calcareous nannoflora. Parts I-IV. Stockholm Contributions in Geology 25, 1-158.