Nannotax3 - ntax_mesozoic

Nannotax3 - ntax_mesozoic - Orastrum Nannotax3 - ntax_mesozoic - Orastrum

Orastrum

Classification: ntax_mesozoic -> Holococcoliths -> Common genera -> Orastrum
Sister taxa: Calculites, Lucianorhabdus, Orastrum, Owenia

Distinguishing features:
Parent taxon (Common genera): The four most commonly recorded genera
This taxon: Holococcoliths with narrow rim surrounding a central-area formed of 1-4 blocks. Typically non-cavate with no spine. Rim bright and central plate dark

Daughter taxa (time control age-window is: 0-800Ma)
				4 central blocks
				Orastrum asarotum Central plate of 4, high birefringence blocks - obliquely oriented; central pore. Medium sized (ca. 4-6 µm)
				Orastrum campanensis Central plate of 4, low birefringence, blocks - one per quadrant. Large (ca 8-11 mm)
				Orastrum porosuturalis Central plate of 4, low birefringence, blocks - one per quadrant, pores along the sutures. Medium sized (ca 4-8 µm)
				1 central block
				Orastrum perspicuum Single, low birefringence, central plate with 1 or 2 perforations. Small (ca 3-5 µm)
				Orastrum robinsonii Single, low birefringence, central plate with indistinct cross-like central structure surrounded by multiple perforations. Medium sized (5-6 µm)
				4 complex blocks
				Orastrum colligatum Holococcolith formed of four large, high birefringence, interlocking blocks forming both a rim and central cross. Medium sized (5-6 µm)
				Orastrum schollei Holococcolith formed of four large, high birefringence, interlocking blocks, with numerous small openings
				Orastrum sp. Specimens not identified to species level

Taxonomy:

Citation: Orastrum Wind & Wise in Wise & Wind, 1977

taxonomic rank: Genus

Type species: Orastrum asarotum Wind & Wise in Wise & Wind, 1977

Farinacci & Howe catalog pages: Orastrum *

Search data:

LITHS: holococcolith, elliptical, CA: ca_disjunct, pores, bar, CROSS-POLARS: rim-unicyclic, V-prominent, R-prominent,

Lith size: 3->11µm;
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 Maastrichtian Stage (100% up, 66Ma, in Danian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within NC7b subzone (113.78-118.27Ma, base in Aptian 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: Common genera

References:

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

Wise, S. W. & Wind, F. H. (1977). Mesozoic and Cenozoic calcareous nannofossils recovered by DSDP Leg 36 drilling on the Falkland Plateau, south-west Atlantic sector of the Southern Ocean. Initial Reports of the Deep Sea Drilling Project. 36(269-491): -. gs O

Orastrum compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 15-9-2024

Taxon Search:

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10821 Go to Archive.is to create a permanent copy of this page - citation notes

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