Taxonomy:
Distinguishing features: Medium size to large (>7 µm) Cruciplacolithus with axial cross-bars that have disjunct, birefringent blocks (‘feet') where they meet the rim.
Farinacci & Howe catalog pages: H. tenuis * , C. helis * , C. notus *
Phylogenetic relations: Thought to have evolved from C. primus, via C. intermedia, by increase in size and development of 'feet'
Tags | LITHS: placolith, elliptical, CA: cross-axial, CSPH: equant, monomorphic, CROSS-POLARS: rim-bicyclic, V-prominent, R-prominent, |
Metrics | Lith size: 7->14µm; Data source notes: lith size from Romein 1979 |
Geological Range:
Last occurrence (top): in mid part of NP9 zone (50% up, 56.5Ma, in Ypresian stage). Data source: Perch-Nielsen 1985, Varol, (1989, fig. 12.4)
First occurrence (base): at base of NP2 zone (0% up, 65.5Ma, in Danian stage). Data source: zonal marker
Plot of occurrence data:
Bown, P. R. (2016). Paleocene calcareous nannofossils from Tanzania (TDP sites 19, 27 and 38). Journal of Nannoplankton Research. 36(1): 1-32. gs V O Bown, P. R., Gibbs, S. J., Sheward, R., O’Dea, S. & Higgins, D. (2014). Searching for cells: the potential of fossil coccospheres in coccolithophore research. Journal of Nannoplankton Research. 34(special): 5-21. gs V O Gohrbandt, K. (1963). Zur Gliederung des Palaogen im Helvetikum nordlich Salzburg nach planktonischen Foraminiferen. Mitteilungen der Geologischen Gesellschaft in Wien. 56: 1-116. gs Hay, W. W., Mohler, H. P., Roth, P. H., Schmidt, R. R. & Boudreaux, J. E. (1967). Calcareous nannoplankton zonation of the Cenozoic of the Gulf Coast and Caribbean-Antillean area, and transoceanic correlation. Transactions of the Gulf-Coast Association of Geological Societies. 17: 428-480. gs V O Mai, H., Hillebrandt-Habel, T., von Salis Perch-Nielsen, K. & Willems, H. (1998). Paleocene coccospheres from DSDP Leg 39, Site 356, Sao Paulo Plateau, S. Atlantic Ocean. Journal of Nannoplankton Research. 20(1): 21-29. gs V O Müller, C. (1974b). Calcareous nannoplankton, Leg 25 (Western Indian Ocean). Initial Reports of the Deep Sea Drilling Project. 25: 579-633. gs V O Okada, H. & Thierstein, H. R. (1979). Calcareous nannoplankton - Leg 43, Deep Sea Drilling Project. Initial Reports of the Deep Sea Drilling Project. 43: 507-573. gs V O Perch-Nielsen, K. (1972b). Remarks on Late Cretaceous to Pleistocene coccoliths from the North Atlantic. Initial Reports of the Deep Sea Drilling Project. 12: 1003-1069. gs V O Perch-Nielsen, K. (1977a). Albian to Pleistocene calcareous nannofossils from the Western South Atlantic, DSDP Leg 39. Initial Reports of the Deep Sea Drilling Project. 39: 699-823. gs V O Pospichal, J. J. & Wise, S. W. (1990a). Calcareous nannofossils across the K/T boundary, ODP hole 690C, Maud Rise, Weddell Sea. Proceedings of the Ocean Drilling Program, Scientific Results. 113: 515-532. gs V O Romein, A. J. T. (1979). Lineages in Early Paleogene calcareous nannoplankton. Utrecht Micropaleontological Bulletin. 22: 1-231. gs V O Stradner, H. (1961). Vorkommen von Nannofossilien im Mesozoikum und Alttertiär. Erdoel-Zeitschrift. 77(3): 77-88. gs Stradner, H., Aubry, M. -P. & Bonnemaison, M. (2010). Calcareous nannofossil type specimens in the collection of the Geological Survey of Austria: A taxonomic and stratigraphic update. Jahrbuch der Geologischen Bundesanstalt. 150(1-2): 9-84. gs V O Thibault, N., Minoletti, F. & Gardin, S. (2018). Offsets in the early Danian recovery phase in carbon isotopes: Evidence from the biometrics and phylogeny of the Cruciplacolithus lineage. Revue de Micropaléontologie. 61(2): 207-221. gs Varol, O. (1989c). Palaeocene calcareous nannofossil biostratigraphy. In, Crux, J. A. & van Heck, S. E. (eds) Nannofossils and their applications: Proceedings of the 2nd INA Conference, London 1987. British Micropalaeontological Society Publication Series. 265-310. gs V O Varol, O. (1998). Palaeogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 200-224. gsReferences:
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Cruciplacolithus tenuis compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 28-2-2021
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