|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
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 *Search data:
|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:
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