Nannotax3 - ntax_cenozoic - Micrantholithus bulbosus

Citation: Micrantholithus bulbosus Bouché, 1962

Variants:

Micrantholithus ornatus Sullivan 1965- slightly more ornate but very similar.

Taxonomic discussion: This species seems to intergrade with various oher species. In particular it is similar to Micrantholithus flos but has raised ridges around the sutures that widen at their ends, resembling discoaster bifurcations.
it is also similar to Micrantholithus angulosus - but with simpler ray tips. Finally Pemma basquense is similar but with the bifurcations touching.

Distinguishing features:
Parent taxon (Micrantholithus): Pentaliths with sutures emerging through corners; edge often indented giving stellate outline
This taxon: Micrantholithus with relatively straight edges and raised ridges around the sutures that widen at their ends.

Geological Range:
Last occurrence (top): within NP15b subzone (44.12-45.49Ma, top in Lutetian stage). Data source: [PRB rough estimate]
First occurrence (base): within NP14b subzone (46.29-47.84Ma, base in Lutetian stage). Data source: [PRB rough estimate]

References:

Bouché, P. M. (1962a). Nannofossiles calcaires de Lutétien du Bassin de Paris. Revue de Micropaléontologie. 5: 75-103. gs

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

Bybell, L. M. & Gartner, S. (1972). Provincialism among mid-Eocene calcareous nannofossils. Micropaleontology. 18(319-336): -. gs

Bybell, L. (1975). Middle Eocene calcareous nannofossils at Little Stave Creek, Alabama. Tulane Studies in Geology and Paleontology. 11(4): 177-247. gs V O

Stradner, H. & Papp, A. (1961). Tertiäre Discoasteriden aus Österreich und deren stratigraphische Bedeutung mit Hinweisen auf Mexico, Rumanien und Italien. Jahrbuch der Geologischen Bundesanstalt, Sonderband. 7: 1-159. gs V O

Stradner, H. (1959a). Die fossilen Discoasteriden Osterreichs. II. Erdoel-Zeitschrift. 75(12): 472-488. gs

Sullivan, F. R. (1965). Lower Tertiary nannoplankton from the California Coast Ranges. II. Eocene. University of California Publications in Geological Sciences. 53: 1-74. gs

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

Micrantholithus bulbosus

References:

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