Nannotax3 - ntax_cenozoic - Micrantholithus astrum

Micrantholithus astrum

Classification: ntax_cenozoic -> Braarudosphaerales -> Braarudosphaeraceae -> Micrantholithus -> Micrantholithus astrum
Sister taxa: M. breviradiatus, M. disculus, M. flos ⟩⟨ M. astrum, M. entaster, M. excelsus, M. hebecuspis, M. minimus, M. pinguis, M. vesper ⟩⟨ M. attenuatus, M. mirabilis ⟩⟨ M. angulosus, M. bramlettei, M. bulbosus, M. crenulatus, M. tinus, M. sp.

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Taxonomy:

Citation: Micrantholithus astrum Bown, 2005

Rank: Species

Taxonomic discussion: Similar to Micrantholithus stellatus Aguado in Aguado et al., 1997 from the Lower Cretaceous. Rays are broader than Micrantholithus aequalis Sullivan, 1964.

Micrantholithus vesper Deflandre 1950 has been widely used in this sense and arguably is a senior synonym.

Distinguishing features:
Parent taxon (Micrantholithus): Pentaliths with sutures emerging through corners; edge often indented giving stellate outline
This taxon: Medium sized Micrantholithus with deeply indented sides and rounded apices.

Farinacci & Howe catalog pages: M. astrum *

Search data:

Tags	LITHS: nannolith-radiate, pentagonal, star-shaped, CROSS-POLARS: T-prominent,
Metrics	Lith size: 7->15µm; Segments: 5->5; Liths per sphere: 12->12 Data source notes: lith size (diameter) from OD & illustrated specimens; lith numbers assumed from geometry

The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within NP21 zone (32.92-34.44Ma, top in Rupelian stage). Data source: [PRB rough estimate]
First occurrence (base): within NP5 zone (59.54-61.51Ma, base in Selandian stage). Data source: [PRB rough estimate]

Plot of occurrence data:

Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
(NB There is no histogram as there are no occurrence records for the taxon in the Neptune database) Parent: Micrantholithus

References:

Bown, P. R. (2005d). Palaeogene calcareous nannofossils from the Kilwa and Lindi areas of coastal Tanzania (Tanzania Drilling Project 2003-4). Journal of Nannoplankton Research. 27(1): 21-95. gs V O

Bown, P. R. (2016). Paleocene calcareous nannofossils from Tanzania (TDP sites 19, 27 and 38). Journal of Nannoplankton Research. 36(1): 1-32. gs V O

Jones, A. P. & Dunkley Jones, T. (2020). Middle Eocene to Early Oligocene calcareous nannofossils from the Nanggulan Formation, Java, Indonesia. Journal of Nannoplankton Research. 30(1): 57-79. gs V O

Self-Trail, J. (2011). Paleogene Calcareous Nannofossils of the South Dover Bridge core, Southern Maryland (USA). Journal of Nannoplankton Research. 32(1): 1-28. gs V O