Taxonomy:
Distinguishing features: Large, circular Pemma with a diagnostic thin base with crenulated edges. Central area consists of a layer of basal thickenings superimposed on the base, resulting in a hazy appearance of the outer edge of the nannolith and a central area more highly birefringent than the edges.
Farinacci & Howe catalog pages: P. bybelliae *
Morphology: Similar in shape to P. rotundum, which lacks the thin base exhibited by P. bybelliae. Pemma balium is the only other described member of this genus to exhibit a thin base, and it is easily distinguished from P. bybelliae by its subcircular outline (Self-Trail 2011).
Size: Diamter 7.5-13.5µm
Tags | LITHS: nannolith-radiate, pentagonal, CA: pores, CROSS-POLARS: T-prominent, |
Metrics | Lith size: 7->14µm; Segments: 5->5; Data source notes: lith size (diameter) from OD |
Geological Range:
Last occurrence (top): within NP16 zone (40.40-42.87Ma, top in Bartonian stage). Data source: Self-Trail 2011
First occurrence (base): within NP16 zone (40.40-42.87Ma, base in Lutetian stage). Data source: Self-Trail 2011
Plot of occurrence data:
![]() |
Pemma bybelliae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 26-2-2021
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=1036 Go to Archive.is to create a permanent copy of this page - citation notes |