Classification: Coccolithophores -> Discoasterales -> Heliolithaceae -> Bomolithus
Sister taxa: Bomolithus, Heliolithus,
|Daughter taxa: (blue => in age window 0-800Ma) |
| Medium-sized, circular heliolith with at least two discernible cycles in LM, both of which are dark in XPL. The cycles comprise around 40 visible radial elements and the central area is typically closed.|
| Similar to B. megastypus but fewer rays and inner cycle less elevated|
| Medium to large rosette-shaped discoasteralid with prominent, broad birefringent cycle (greater than half the lith diameter).|
| Medium to large rosette-shaped discoasteralid with prominent, narrow birefringent boss (equal to or less than half the lith diameter).|
| Circular lith with three distinct cycles, only the innermost exhibiting birefringence in XPL; the central area is a narrow hole or closed. The outermost cycle is dark in phase contrast and the distinct elements show obliquity. The innermost cycle shows white interference colours and is crossed by thick extinction lines that are rotated approximately 5° from axial.|
| Specimens which cannot be assigned to any established species|
Citation: Bomolithus Roth, 1973Rank: GenusType species: Bomolithus elegans Roth, 1973.Notes & discussion: The genus Discoasteroides Bramlette & Sulivan 1961 was used at one time for many of these speceis. However, the type species D. kuepperi is a regular discoaster. See also discussion in Young & Bown 2014 (p.42).
Distinguishing features: Discoidal discoasteralids with a wide non-birefringent cycle and at least one narrower birefringent cycle, i.e., narrower than the diameter of the nannolith.
Farinacci & Howe catalog pages: Bomolithus *
The morphological data given here can be used on the advanced search page. See also these notes
|Tags||LITHS: nannolith-radiate, circular, star-shaped, CROSS-POLARS: V-prominent, R-prominent, |
|Metrics||Lith size: 5->12µm; |
Last occurrence (top): at base of Ypresian Stage (1% up, 55.9Ma, in Ypresian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Selandian Stage (4% up, 61.5Ma, in Selandian stage). Data source: Total of range 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
- Neptune data: This is a higher taxon page so Neptune data is not plotted. See also: customisable plot Parent: Heliolithaceae
Bown, P. R. (2010). Calcareous nannofossils from the Paleocene/Eocene Thermal Maximum interval of southern Tanzania (TDP Site 14). Journal of Nannoplankton Research. 31(1): 11-38. gs V O
Roth, P. H. (1973). Calcareous nannofossils: Leg 17 of the Deep Sea Drilling Project. Initial Reports of the Deep Sea Drilling Project. 17: 695-795. gs V O
Young, J. R. & Bown, P. R. (2014). Some emendments to calcareous nannoplankton taxonomy. Journal of Nannoplankton Research. 33(1): 39-46. gs V O