Distinguishing features:
Parent taxon (Helicolithus): Loxolith coccoliths with bicyclic rim with broad inner cycle and narrow central-area, filled by broad cross bars. The rim image is distinctly bicyclic and the inner cycle and cross bars are birefringent.
This taxon: Large (>6µm) Helicolithus with axial cross bars. Longitudinal bar longer than transverse bar.
Taxonomy:
Farinacci & Howe catalog pages: H. turonicus *
Distinguishing features:
Parent taxon (Helicolithus): Loxolith coccoliths with bicyclic rim with broad inner cycle and narrow central-area, filled by broad cross bars. The rim image is distinctly bicyclic and the inner cycle and cross bars are birefringent.
This taxon: Large (>6µm) Helicolithus with axial cross bars. Longitudinal bar longer than transverse bar.
Search data:
LITHS: murolith, elliptical, CA: cross-axial, ca_disjunct, closed, CROSS-POLARS: rim-bicyclic, V-prominent, R-prominent, |
Lith size: 5->8µm; Data source notes: original description & illustrated specimens |
Geological Range:
Last occurrence (top): in upper part of UC9c subzone (60% up, 88.1Ma, in Coniacian stage). Data source: Burnett 1998, fig. 6.4
First occurrence (base): in upper part of UC8a subzone (60% up, 90.3Ma, in Turonian stage). Data source: Burnett 1998, fig.6.3
Plot of occurrence data:
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 Linnert, C., Mutterlose, J. & Erbacher, J. (2010). Calcareous nannofossils of the Cenomanian/Turonian boundary interval from the Boreal Realm (Wunstorf, northwest Germany). Marine Micropaleontology. 74: 38-58. gs Mortimer, C. P. (1987). Upper Cretaceous Calcareous Nannofossil Biostratigraphy of the Southern Norwegian and Danish North Sea Area. Abhandlungen der Geologischen Bundesanstalt. 39: 143-175. gs Püttmann, T. & Mutterlose, J. (2019). Calcareous nannofossils from a Late Cretaceous nearshore setting. Journal of Nannoplankton Research. S4: 81-88. 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. gsReferences:
Helicolithus turonicus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 8-9-2024
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10512 Go to Archive.is to create a permanent copy of this page - citation notes |
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