Daughter taxa (time control age-window is: 0-800Ma)![]() | ||||
Sphenolithus disbelemnos cylindroconical with short spine and high base | ||||
Sphenolithus dissimilis cylindroconical with long spine and high base | ||||
![]() | Sphenolithus procerus cylindroconical with long spine and low base | |||
![]() | ![]() | Sphenolithus tintinnabulum Distinctive triangular outline and very short multipartite spine. (NB The name tininnabulum means small bell and describes the shape). | ||
Sphenolithus paratintinnabulum Cylindroconical with short spine and low base (like S. tintinnabulum but less triangular) | ||||
Sphenolithus truaxii cylindroconical with long spine, high base and a distinct central bulge |
Taxonomy:
Distinguishing features: Bases cylindrical or conical, compound apical spine
Farinacci & Howe catalog pages: dissimilis group [no catalog entry yet]
Morphology: Sphenoliths with bases that are either cylindrical or slightly conical (minimal taper distally) are placed within this group (Table 4). In specimens with high bases, the extinction lines cross and then parallel the lateral periphery (S. dissimilis, S. disbelemnos); if their bases are low, the extinction lines cross and continue to diverge (S. procerus, S. paratintinnabulum). All five species included in this group have compound apical spines. Sphenolithus cometa is closely related to members of this group (S. procerus and S. dissimilis), but is placed within the biconical Group 3 because of its narrowly divergent spine. [Bergen et al. 2017].
See also: Sphenolithus belemnos - probably directly related, but with monocrystalline spine;
Search data:Tags | LITHS: |
Metrics | Lith size: 0->0µm; |
Geological Range:
Notes: This group of sphenolths is characteristic of the Early Miocene in NN3 it gives rise to S. belemnos and then disappears (subsequent sphenolith assemblages are dominated by S. heteromorphus).
Last occurrence (top): in upper part of Burdigalian Stage (56% up, 17.9Ma, in Burdigalian stage). Data source: Total of range of species in this database
First occurrence (base): in lower part of Bartonian Stage (22% up, 40.4Ma, in Bartonian stage). Data source: Total of range of species in this database
Plot of occurrence data:
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. gs V O Maiorano, P. & Monechi, S. (1997). New Early Miocene species of Sphenolithus Deflandre, 1952 from the North Atlantic Ocean. Journal of Nannoplankton Research. 19(2): 103-107. gs V OReferences:
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S. dissimilis group compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 14-4-2021
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