Nannotax3 - Mesozoic

Percivalia

Classification: Mesozoic -> Eiffellithales -> Rhagodiscaceae -> Percivalia
Sister taxa: Calcicalathina, Percivalia, Rhagodiscus, Zebrashapka,

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: (blue => in age window 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

Rank: Genus

Type species: Percivalia porosa Bukry, 1969

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 remarks: 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:

Tags	LITHS: murolith, elliptical, CA: cross-axial, plate, process, diagonal cross, bar, closed, R-UNITS: R-prominent, DETAILS: rim-unicyclic,
Metrics	Lith size: 4->9µm; Sources: 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): 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:

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). 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. The University of Kansas Paleontological Contributions. Article 51 (Protista 2): 1-79. gs :: ::

Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 132-199. gs :: ::

Percivalia compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 3-6-2020

Taxon Search:

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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

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