Daughter taxa (time control age-window is: 0-800Ma)![]() | ||||
![]() | Pemma basquense Pemma with crenulate edges. | |||
Pemma bybelliae 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. | ||||
![]() | ![]() | ![]() | ![]() | Pemma papillatum Pemma with multiple nodes along the outer margin of each pentalith. |
Pemma rotundum Circular Pemma species | ||||
![]() | Pemma stradneri Angular Pemma species with ray tips extending beyond the pentagonal periphery | |||
![]() | ![]() | ![]() | ![]() | Pemma uncinata Large (typically >7 µm), triangular-, rectangular- or rhomb-shaped nannoliths, which are thickened along two sides (‘base’ and ‘side’) to give a hook-shaped appearance. Dark in XPL but birefringent where thickened; c-axis orientation is parallel with the long axis. |
![]() | ![]() | ![]() | ![]() | Pemma sp. Specimens which cannot be assigned to any established species |
Taxonomy:
Distinguishing features:
Parent taxon (Braarudosphaeraceae): Coccospheres pentagonal dodecahedra formed of five pentagonal plates
This taxon: Pentaliths with a central depression/perforation in each segment; often producing elevated, robust structures that are commonly observed in side view.
Farinacci & Howe catalog pages: Pemma *
Search data:
LITHS: nannolith-radiate, pentagonal, CA: pores, CROSS-POLARS: T-prominent, |
Lith size: 5->18µm; Segments: 5->5; |
Geological Range:
Last occurrence (top): at top of NP21 zone (100% up, 32.9Ma, in Rupelian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within NP14b subzone (46.29-47.84Ma, base in Lutetian stage). Data source: Total of ranges of species in this database
Plot of occurrence data:
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Pemma compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 28-4-2025
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=1034 Go to Archive.is to create a permanent copy of this page - citation notes |
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