Set number: 862

  • Sphenolithus alatus 27147 1
  • Sphenolithus alatus 27142 2
  • Sphenolithus alatus 27145 3
  • Sphenolithus alatus 27149 4
  • Sphenolithus alatus 27146 5
  • Sphenolithus alatus 27143 6
  • Sphenolithus alatus 27144 7
  • Sphenolithus alatus 27148 8
    10µm
Sphenolithus alatus, Middle Miocene, DSDP Leg 25, Site 242, Mozambique Channel (Davie Ridge), Indian Ocean

Set number: 861

  • Sphenolithus alatus 27137 1
  • Sphenolithus alatus 27134 2
  • Sphenolithus alatus 27139 3
  • Sphenolithus alatus 27141 4
  • Sphenolithus alatus 27136 5
  • Sphenolithus alatus 27135 6
  • Sphenolithus alatus 27138 7
  • Sphenolithus alatus 27140 8
    10µm
Sphenolithus alatus, Middle Miocene, DSDP Leg 25, Site 242, Mozambique Channel (Davie Ridge), Indian Ocean

Set number: 860

  • Sphenolithus alatus 2360 1
  • Sphenolithus alatus 2361 2
  • Sphenolithus alatus 2358 3
  • Sphenolithus alatus 2359 4
    10µm
Sphenolithus alatus, Late Oligocene, Angola, West Africa
Final Epithet
Sphenolithus alatus Varol, in prep.
Basionym

Sphenolithus alatus Varol, in prep.

Diagnosis

A small sphenolith having a short bouquet shape clustered apical cycle, longitudinally aligned lateral cycle at 0° and a hollow frustum shape proximal cycle with slightly convex periphery creates a conical proximal depression.

Etymology

From Latin alatus, wing - referring to its wing-like proximal cycle in axial section.

Description

Small species of Sphenolithus has a hollow frustum shape proximal cycle, lateral cycle with short segments and a bouquet shape cluster apical cycle.

The hollow frustum shape proximal cycle creates a conical proximal depression. In the axial section, a deep triangular proximal depression has an obtuse angle at its apex. The outer surface of the proximal cycle is slightly concave.

The opposite side of the proximal cycle is better seen at 45° and displays an axial c-axis.

The three cycles can be better seen in well-preserved specimens at 45° with the help of the gypsum plate.

The short bouquet shape clustered apical cycle with axial c-axis is not forming a true apical spine.

In the polarised light, the low lateral cycle with a tangential c-axis is aligned longitudinally at 0°.

Remarks

Sphenolithus alatus differs from Sphenolithus abies Deflandre, 1953 ex Deflandre in Deflandre & Fert, 1954, Sphenolithus moriformis (Brönnimann & Stradner, 1960) Bramlette & Wilcoxon,1967 and Sphenolithus apoxis Bergen & de Kaenel in Bergen et al., 2017 by having

- a short bouquet shape clustered apical cycle

- a lateral cycle with longitudinally aligned short segments at 0°

-a proximal cycle with a slightly convex periphery

- a deep conical proximal depression with an obtuse angle

References

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.

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.

Brönnimann, P., Stradner, H., 1960. Die Foraminiferen- und Discoasteriden-zonen von Kuba und ihre interkontinentale Korrelation. Erdoel-Zeitschrift 76(10), 364-369.

Deflandre, G., 1953. Hétérogénéité intrinsèque et pluralité des éleménts dans les coccolithes actuels et fossiles. Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences, Paris 237, 1785-1787.

Deflandre, G., Fert, C., 1954. Observations sur les coccolithophoridés actuels et fossiles en microscopie ordinaire et électronique. Annales de Paléontologie 40, 115-176.