Nannotax3 - ntax_main - Staurolithites laffittei

Citation: Staurolithites laffittei Caratini, 1963

Taxonomic discussion: The original description of the species contains no useful details and the LM illustration is very poor, the accompanying sketch suggests a medium-sized, bicyclic Staurolithites with a wide central opening spanned by simple axial crossbars slightly narrower than the rim width. There does not appear to have been any modern redescription of the species but Burnett (1998) used the name in this sense, and this has been followed by other workers. [my interpretation - JRY 2021]

Distinguishing features:
Parent taxon (Staurolithites): 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. NB The bicyclic/unicyclic separation is simply controlled by how far the inwards the R-units develop so, although it is a useful identification criterion, it almost certainly has no real phylogenetic significance and would be a very poor character for defining genera.
This taxon: Medium sized (5-7 µm), bicyclic, with simple cross-bars

Original description: Corpuscule calcaire elliptique: longueur: 5 à 7 µ largeur: 3,5 à 5 µ épaisseur: 1,3 à 1,6 µ Une couronne périphérique est arrondie vers l'extérieur. Intérieurement, son épaisseur di- minue ce qui forme un rebord. Seule la bordure externe porte des striations plus ou moins profondes et irrégulièrement réparties. Une croix dont le grand bras est disposé selon le grand axe de l'ellipse, le petit étant à peu près perpendiculaire à celui-ci en son milieu, occupe le centre du coccolithe. Les bras de cette croix sont cylindriques. Ils ont un diamètre de 1 µ environ.

Approximate translation [lightly edited from google translate, JRY Jan 2021]

Elliptical calcareous body: length: 5 to 7 µm width: 3.5 to 5 µm thickness: 1.3 to 1.6 µm. The rim is rounded outwards. Internally, its thickness decreases which forms a flange. Only the outer border bears more or less deep and irregularly distributed striations. A cross whose larger arm is arranged along the major axis of the ellipse, the small being approximately perpendicular to it in its middle, occupies the center of the coccolith. The arms of this cross are cylindrical. They have a diameter of approximately 1 µm.

Geological Range:
Last occurrence (top): at top of Maastrichtian Stage (100% up, 66Ma, in Danian stage). Data source: Lees & Bown 2005 - consistently present to end Cret
First occurrence (base): within Albian Stage (100.50-113.20Ma, base in Albian stage). Data source: Burnett 1998

References:

al Rawahi, Z. & Dunkley Jones, T. (2019). Calcareous nannofossil assemblages of the Late Cretaceous Fiqa Formation, north Oman. Journal of Micropalaeontology. 38(1): 25-54. 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

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 O

Kanungo, S., Bown, P. R. & Gale, A. S. (2020). Cretaceous (Albian-Turonian) calcareous nannofossil biostratigraphy of the onshore Cauvery Basin, southeastern India. Cretaceous Research. 118 [2021]: 1-22. gs

Lees, J. A. & Bown, P. R. (2005). Upper Cretaceous calcareous nannofossil biostratigraphy, ODP Leg 198 (Shatsky Rise, Northwest Pacific Ocean). Proceedings of the Ocean Drilling Program, Scientific Results. 198: 1-60. gs

Thibault, N. (2010). Calcareous nannofossils from the boreal Upper Campanian- Maastrichtian chalk of Denmark. Journal of Nannoplankton Research. 31(1): 39-56. gs

Staurolithites laffittei

References:

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