Distinguishing features: Large, robust sphenolith with squat, square base and short, sharply tapering spine.
Farinacci & Howe catalog pages: Sphenolithus arthurii *
Morphology remarks: The base is coarsely constructed, square-shaped, and crossed by an extinction cross at 0°; the lower and upper quadrants are near equidimensional. At 45° the base is crossed by diagonal extinction lines. The spine is short (equal to or shorter than the base) and tapers sharply to a point. The spine is compound and may be divided by a median extinction line at 0°, where it is darkest but still visible. The spine is brightest at 45°.
|Tags||LITHS: nannolith-radiate, N: 3D-radiate, conical, circular, cylindrical, CA: process, PROCESS: length-fast, multicrystalline, spine, |
CSPH: not known, V-UNITS: V-prominent, R-UNITS: all, lower-tier, spine, middle-tier, R-prominent, DETAILS: isogyres radial,
|Metrics||Lith size: 7->11µm; |
Sources: lith height from OD
Last occurrence (top): within NP11 zone (53.70-54.17Ma, top in Ypresian stage). Data source: Bown, 2005c
First occurrence (base): within NP11 zone (53.70-54.17Ma, base in Ypresian stage). Data source: Bown, 2005c
Plot of occurrence data:
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