Nannotax3 - ntax_mesozoic

Nannotax3 - ntax_mesozoic - Percivalia Nannotax3 - ntax_mesozoic - Percivalia

Percivalia

Classification: ntax_mesozoic -> Eiffellithales -> Rhagodiscaceae -> Percivalia
Sister taxa: Percivalia, Rhagodiscus ⟩⟨ Calcicalathina, Zebrashapka

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:

Citation: Percivalia Bukry, 1969

taxonomic rank: Genus

Type species: Percivalia porosa Bukry, 1969

Farinacci & Howe catalog pages: Percivalia *

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:

In proximal view Percivalia shows multiple narrow concentric cycles of elements, rather than a granular structure.
That the central structure shows higher birefirngence in Percivalia than Rhagodiscus
Rhagodiscus species tpyicaly have wide, holowspines whereas in Percivalia they are typically narrow and often solid.

Search data:

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

The morphological data given here can be used on the advanced search page. See also these notes

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:

Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Neptune data: This is a higher taxon page so Neptune data is not plotted. See also: customisable plot Parent: Rhagodiscaceae

References:

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 O

Percivalia compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 15-10-2024

Taxon Search:

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