Micrantholithus disculus Simple, elevated Micrantholithus with rounded outline and elliptical side views.
Micrantholithus flos Micrantholithus with relatively straight edges, sutures often raised
Micrantholithus triquetra Relatively large (typically >5 µm), triangular-shaped nannoliths that thicken along the longer sides and exhibit low birefringence in XPL.
sides deeply indented
Micrantholithus astrum Medium sized Micrantholithus with deeply indented sides and rounded apices.
Micrantholithus entaster Medium sized Micrantholithus with deeply indented sides and elevated central star
Micrantholithus excelsus Large, elevated Micrantholithus with deeply indented sides and gracile, long rays. The height of the pentalith results in a ragged LM appearance.
Micrantholithus hebecuspis Large Micrantholithus with deeply indented sides and blunt, flat-ended apices.
Micrantholithus minimus A small (typically <4 µm) Micrantholithus with raised ridges along the line of the segment sutures that give the appearance of a deeply indented pentalith. Many specimens, however, have thin calcite between the raised, birefringent areas.
Micrantholithus pinguis Medium sized Micrantholithus with deeply indented sides and elevated structure.
Micrantholithus tinus Micrantholithus with bifurcate ray-like extension from each segment (sutures do not go along arms). Resembles a discoaster but evidently shows the birefringence of a pentalith and a specimen of M. concinnus with short rays is illustrated from the same sample so the identification seems well-founded.
Micrantholithus sp. Specimens which cannot be assigned to established species
Taxonomy:
Citation: Micrantholithus Deflandre in Deflandre & Fert 1954Taxonomic rank: genusType species: Micrantholithus flos Deflandre in Deflandre & Fert 1954Variants: Citrocalculus - barrel-shaped in profileTaxonomic discussion: Initially invalidly described in Deflandre 1950, subsequently validated in Deflandre & Fert 1954.
Distinguishing features: Parent taxon (Braarudosphaeraceae): Coccospheres pentagonal dodecahedra formed of five pentagonal plates This taxon: Pentaliths with sutures emerging through corners; edge often indented giving stellate outline
Lith size: 3->30µm; Segments: 5->5; Liths per sphere: 12->12
The morphological data given here can be used on the advanced search page. See also these notes
Geological Range: Notes: Predominantly Palaeogene but it has been sporadically recorded in the Miocene - e.g. Moshkovitz & Ehrlich 1981 Last occurrence (top): at top of Sarmatian Paratethyan stage (100% up, 11.6Ma, in Tortonian stage). Data source: Total of ranges of the species in this database First occurrence (base): within Paleocene Epoch (55.96-66.04Ma, base in Danian stage). Data source: Total of ranges of species in this database
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
Bown, P. R., Rutledge, D. C., Crux, J. A. & Gallagher, L. T. (1998). Lower Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 86-131. gsO
Deflandre, G. & Fert, C. (1954). Observations sur les coccolithophoridés actuels et fossiles en microscopie ordinaire et électronique. Annales de Paléontologie. 40: 115-176. gs
Deflandre, G. (1950a). Observations sur les Coccolithophoridés, à propos d'un nouveau type de Braarudosphaeridé, Micrantholithus, à éléments clastiques. Comptes rendus hebdomaire de l'Académie des sciences, Paris. 231: 1156-1158. gs
Moshkovitz, S. & Ehrlich, A. (1981). Biostratigraphical problems of the Middle Miocene calcareous nannofossils and the palaeoecological significance of the Braaruudosphaerids in the coastal plain and offshore of israel. Geological Survey of Israel Current Research. 198: 43-47. gs
Micrantholithus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 28-4-2025
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