Distinguishing features:
Parent taxon (Rhagodiscaceae): Eiffelithales with V-units forming most of rim (R-units typically thin plates on proximal surface, so LM images are typically unicyclic. Central-areas typically filled by a plate of granular calcite. The central structure may be spine-bearing, perforate or massive.
This taxon: Loxolith coccoliths with narrow outer cycle and wide central area filled with a granular plate or bridge, multiple concentric cycles seen on proximal face.
Daughter taxa (time control age-window is: 0-800Ma) | ||||
Percivalia arata | ||||
Percivalia bullata | ||||
Percivalia dunkleyjonesii Central area filled by indistinct cross transverse bar of which apears as "bright buttons" | ||||
Percivalia fenestrata Loxolith coccoliths with narrow outer cycle and wide central area filled with a granular plate. The plate is distinctly smooth and birefringent in XPL and crossed by curving extinction lines. | ||||
Percivalia hauxtonensis | ||||
Percivalia howardii | ||||
Percivalia imperfossa | ||||
Percivalia pearsonii Central area filled by dark axial cross | ||||
Percivalia pontilitha | ||||
Percivalia porosa | ||||
Percivalia nebulosa Percivalia with a granular central plate in the form of an axial cross. | ||||
Percivalia sp. Specimens not identified to species level |
Taxonomy:
Farinacci & Howe catalog pages: Percivalia *
Distinguishing features:
Parent taxon (Rhagodiscaceae): Eiffelithales with V-units forming most of rim (R-units typically thin plates on proximal surface, so LM images are typically unicyclic. Central-areas typically filled by a plate of granular calcite. The central structure may be spine-bearing, perforate or massive.
This taxon: Loxolith coccoliths with narrow outer cycle and wide central area filled with a granular plate or bridge, multiple concentric cycles seen on proximal face.
Morphology:
LITHS: murolith, elliptical, CA: bar, closed, cross-axial, diagonal cross, plate, process, CROSS-POLARS: R-prominent, rim-unicyclic, |
Lith size: 4->9µm; Data source notes: size range of included species |
Geological Range:
Last occurrence (top): at top of Early Maastrichtian Substage (100% up, 70.1Ma, in Maastrichtian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within Tithonian Stage (143.10-149.24Ma, base in Tithonian stage). Data source: Total of ranges of species in this database
Plot of occurrence data:
Aguado, R., Company, M. & Tavera, J. M. (2000). The Berriasian/Valanginian boundary in the Mediterranean region: new data from the Caravaca and Cehegín sections, SE Spain. Cretaceous Research. 21: 1-21. gs Bown, P. R., Rutledge, D. C., Crux, J. A. & Gallagher, L. T. (1998). Lower Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 86-131. gs O Bukry, D. (1969). Upper Cretaceous coccoliths from Texas and Europe. University of Kansas Paleontological Contributions, Articles. 51 (Protista 2): 1-79. gs O Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 132-199. gs OReferences:
Percivalia compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 14-12-2024
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10870 Go to Archive.is to create a permanent copy of this page - citation notes |
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