Staurolithites


Classification: Mesozoic -> Eiffellithales -> Chiastozygaceae -> Staurolithites
Sister taxa: Amphizygus, Archaeozygodiscus, Gorkaea, Placozygus, Reinhardtites, Tranolithus, Zeugrhabdotus, Staurolithites, Diadorhombus, Rhabdophidites, Ahmuellerella, Bukrylithus, Heteromarginatus, Misceomarginatus, Monomarginatus, Neocrepidolithus, Vacherauvillius, Chiastozygus, Braloweria, Clepsilithus, Crepidolithus, Loxolithus, Tubirhabdus,

Distinguishing features: Loxolith muroliths with relatively narrow rim and wide central area spanned by axial cross bars. The cross is usually spine bearing. Inner/proximal rim cycle is variably developed and so the LM image may be unicyclic or bicyclic.


Daughter taxa: (blue => in age window 0-800Ma)
Unicyclic, no special features
Small to medium-sized Staurolithites with a narrow wall that is not discernibly bicyclic in the LM, and an axially aligned central cross.

Unicyclic rim and broad, medianly split, cross-bars.


Small Staurolithites with narrow rim and wide central area spanned by narrow cross bars.
unicyclci with a distinguishing feature
Staurolithites with partial grill of minor crossbars extending from the main crossbars
minute (<2µm long)
Rim unicyclic, crossbars brighter than rim and each bar behaves as a single crystal unit.
Small (3-4 µm), rim unicyclic, crossbars faint, with bright spine-top
Small (holotype 3.7 µm) with virtually closed central area and very small cross
Small (holotype 3 µm), unicyclic, transverse bar much brighter than longitudinal bar
Small, with very large spine
Small (2-4 µm) Staurolithites with relatively broad, tapering axial cross bars, open spine base
A large species of Staurolithites (c. 8µm) with a broad, unicyclic, birefringent rim and blocky, birefringent, largely featureless axial cross
unicycle -rotated or twisted bcrossbars
Smallish species (<6µm) with high rim and S-shaped longitudinal cross-bar
Staurolithites with a narrow axial cross that may be slightly rotated from axial; the longitudinal bars curve as they meet the coccolith rim. Unicyclic rim image, though the rim is crossed by curving extincton lines.
Small, delicate Staurolithites with cross bars that are rotated from axial by 30-40°. Unicyclic rim image in XPL.
bicyclic rim
Broadly elliptical with wide central area spanned by narrow crossbars. 
Small (3-4 µm), rim bicyclic, crosbars bright in 0° position
Large species of Staurolithites (c. 7.0 µm) with a narrowly elliptical, diffusely bicyclic rim and a broad axial cross. Both rim and cross display grey interference colours. At 45° to the polarising directions the cross bars display a distinct, median extinction line. The cross bars show patches of brighter interference colours near their junction with the rim.

Staurolithites with broad birefringent cross bars. Bicyclic rim image in XPL, but the bright inner cycle is narrow.
Bicyclic species with narrow rim, triangular feet to the crossbars give the species a distinctive LM appearance.
Small (holotype 4 µm) bicyclic Staurolithites with narrow central area filled with a narrow axial cross. The bright inner cycle is broader than the outer cycle.
bicyclic - rotated or twisted central cross
Large (~7 µm), Staurolithites species with bars rotated 10-20° from axial; the bars of this cross are split along their length and flare towards their juncture with the rim.
Distinctive Staurolithites with a rim composed of two equally birefringent cycles, separated by spirally-arranged extinction gyres, and a central cross slightly rotated from axial.
Medium sized (6-7 µm), bicyclic, axial cross slightly twisted.
bicyclic - large, complex central cross
cross with complex structure
Rim bicyclic central area with plate around the cross
Rim bicyclic, bars bright and with medial extinction line
Bicyclic with thick cross-bars which flare toward the centre, where they suport the base of a hollow spine.
long elliptical with broad crossbars
Broad cross almost fills central area and shows windmill-like extinction

Specimens not identified to species level

Taxonomy:

Citation: Staurolithites Caratini, 1963
Rank: Genus
Type species: Staurolithites laffittei Caratini, 1963.
Variants: Bownia Varol & Girgis (1994) - bicyclic (see Staurolithites mutterlosei for discussion)
Synonyms:
Notes & discussion: Numerous names have been proposed for loxolith muroliths with an axial cross but it is now accepted that Staurolithites has priority and so the various species are now conventionally placed in this genus.

Farinacci & Howe catalog pages: Staurolithites * , Ephippium * , Vekshinella + * , Vagalapilla * , Staurorhabdus * , Haslingfieldia * , Bownia * , Zygostephanos *

Distinguishing features: Loxolith muroliths with relatively narrow rim and wide central area spanned by axial cross bars. The cross is usually spine bearing. Inner/proximal rim cycle is variably developed and so the LM image may be unicyclic or bicyclic.


Morphology remarks: Practically a form-genus for loxoliths with a simple axial cross. Staurolithites is the oldest genus name proposed for loxoliths with an axial cross, and the other (widely used) genera listed below are considered synonymous.

Geological Range:
Last occurrence (top): at top of Maastrichtian Stage (100% up, 66Ma, in Maastrichtian stage). Data source: Total of range of species in this database
First occurrence (base): in mid part of Sinemurian Stage (47% up, 195.3Ma, in Sinemurian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Black, M. (1973). British Lower Cretaceous Coccoliths. I-Gault Clay (Part 2). Palaeontographical Society Monograph. 127: 49-112. gs

Bown, P. R. & Cooper, M. K. E. (1998). Jurassic. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 34-85. 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

Caratini, C. (1963). Contribution à l'étude des coccolithes du Cénomanien supérieur et du Turonien de la région de Rouen. PhD thesis, Université d'Alger, Faculté des Sciences, Publication du Laboratoire de Géologique Appliquée. -. gs

Gartner, S. (1968). Coccoliths and related calcareous nannofossils from Upper Cretaceous deposits of Texas and Arkansas. The University of Kansas Paleontological Contributions. Article 48 (Protista 1): 1-56. gs

Loeblich, A. R. & Tappan, H. (1963). Type fixation and validation of certain calcareous nannoplankton genera. Proceedings of the Biological Society of Washington. 76: 191-198. gs

Noël, D. (1973). Nannofossiles calcaires de sédiments jurassiques finement laminés. Bulletin du Muséum National d'Histoire Naturelle. 3e serie, 75: 95-156. gs

Varol, O. & Girgis, M. (1994). New taxa and taxonomy of some Jurassic to Cretaceous calcareous nannofossils. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen. 192: 221-253. gs

Vekshina, V. N. (1959). Coccolithophoridae of the Maastrichtian deposits of the West Siberian lowlands. Siberian Science Research Institute of Geology Geophysics Mineralogy and Raw Materials. 2: 56-81. gs


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Staurolithites compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 15-12-2019

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