Rhomboaster contortus

(Stradner, 1959) (Bybell & Self-Trail, 1995) Varol, n. comb. Sept 11, 2026

Set number: 4513

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10µm

Rhomboaster contortus, Early Eocene, Santos Basin, Brazil

Set number: 4515

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10µm

Rhomboaster contortus, Early Eocene, Santos Basin, Brazil

Set number: 4514

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10µm

Rhomboaster contortus, Early Eocene, Santos Basin, Brazil

Set number: 4485

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10µm

Rhomboaster contortus, Early Eocene, Walker Ridge, Gulf of Mexica

Final Epithet

Rhomboaster contortus (Stradner, 1959) (Bybell & Self-Trail, 1995) Varol, n. comb.

Basionym

Discoaster contortus Stradner, 1959

Synonyms

Rhomboaster contortus (Stradner, 1958) Bybell & Self-Trail, 1995; invalid according to ICN Art. 41.5 because a full and direct reference to the place of valid publication of the basionym was not provided.

Tribrachiatus contortus (Stradner, 1959a) Howe & Bord, 2025

Remarks

The epitype designated by Howe & Bord (2025) is not justified under ICN Art. 9.9. Their interpretation that the holotype was reworked from Eocene into Miocene sediments does not, in itself, render the holotype demonstrably ambiguous or prevent its critical identification. Reworking is a stratigraphic circumstance and does not constitute a basis for epitypification.

References

Bybell, L. M. & Self-Trail, J. 1995. Evolutionary, biostratigraphic and taxonomic study of calcareous nanofossils from a continuous Palaeocene-Eocene boundary section in New Jersey. U.S. Geological Survey, Professional Paper. 1554: 1-36.

Howe, R. & Bord, D. (2025). Taxonomic Note – The status of Tribrachiatus contortus. Journal of Nannoplankton Research. 43(1): 1-4.

Taxonomy

Rhomboaster

Uncategorised

Biostratigraphy

Stratigraphic Range

Ypresian

Age (Ma)

54.70 - 54.09