Distinguishing features: 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: 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: Rather poorly constrained and applied genus. Nature of the type species, described from EM, is uncertain. Distinction from Rhagodiscus is discussed by Aguado et al. (2000), who noted three differences between the genera:
Tags | LITHS: murolith, elliptical, CA: cross-axial, plate, process, diagonal cross, bar, closed, CROSS-POLARS: rim-unicyclic, R-prominent, |
Metrics | Lith size: 4->9µm; Data source notes: size range of included species |
Geological Range:
Last occurrence (top): in lower part of Maastrichtian Stage (36% up, 69.9Ma, in Maastrichtian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Tithonian Stage (0% up, 152.1Ma, in Tithonian stage). Data source: Total of range 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). Early Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 86-131. gs Bukry, D. (1969). Upper Cretaceous coccoliths from Texas and Europe. University of Kansas Paleontological Contributions, Articles. 51 (Protista 2): 1-79. gs V O Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 132-199. gs V OReferences:
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Percivalia compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 27-1-2021
Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10870 Go to Archive.is to create a permanent copy of this page - citation notes |