Distinguishing features: 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.
Farinacci & Howe catalog pages: Micrantholithus tinus *
Morphology remarks: Some similarity to M. bramlettei but rays are much longer.
|Tags||LITHS: nannolith-radiate, pentagonal, |
CSPH: not known, T-UNITS: all, T-prominent,
|Metrics||Lith size: 18->22µm; Segments: 5->5; Liths per sphere: 12->12|
Sources: lith size (diameter) from OD; lith numbers assumed from geometry
Last occurrence (top): within NP13 zone (49.11-50.50Ma, top in Ypresian stage). Data source: Kapellos & Schaub 1973
First occurrence (base): within NP12 zone (50.50-53.70Ma, base in Ypresian stage). Data source: Kapellos & Schaub 1973
Plot of occurrence data:
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