Chiasmolithus oamaruensis

Classification: ntax_cenozoic -> Coccolithales -> Coccolithaceae -> Chiasmolithus -> C. bidens group -> Chiasmolithus oamaruensis
Sister taxa: C. altus, C. bidens, C. edentulus, C. eoaltus, C. eograndis, C. expansus, C. grandis, C. medius, C. modestus, C. oamaruensis, C. solitus


Citation: Chiasmolithus oamaruensis (Deflandre, in Deflandre & Fert, 1954) Hay et al., 1966
Rank: Species
Basionym: Tremalithus oamaruensis Deflandre in Deflandre & Fert, 1954

Distinguishing features: Large to very large Chiasmolithus with broad centro-distal cycle, wide central area and straight, narrow, symmetrical diagonal bars, which join at a relatively acute angle along the minor axis.

Farinacci & Howe catalog pages: T. oamaruensis *

Phylogenetic relations: Firth & Wise (1992) discussed intergradations between Chiasmolithus oamaruensis, C. altus and C. expansus. Persico & Villa (2008) discuss intergradations between Chiasmolithus oamaruensis, C. altus, C. eoaltus and C. solitus

Search data:
TagsLITHS: placolith, elliptical, CA: ca_disjunct, diagonal cross,
CSPH: equant, monomorphic, CROSS-POLARS: rim-bicyclic, V-prominent, R-prominent,
MetricsLith size: 10->20µm;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: Older stratigraphic range (NP16) has been reported at high southern latitudes (Persico & Villa, 2008, JNR).
Last occurrence (top): within NP22 zone (32.02-32.92Ma, top in Rupelian stage). Data source: Perch-Nielsen 1985b
First occurrence (base): at base of NP18 zone (0% up, 37.3Ma, in Priabonian stage). Data source: zonal marker (see Perch-Nielsen 1985)

Plot of occurrence data:


Bown, P. R. & Dunkley Jones, T. (2012). Calcareous nannofossils from the Paleogene equatorial Pacific (IODP Expedition 320 Sites U1331-1334). Journal of Nannoplankton Research. 32(2): 3-51. gs V O

de Kaenel, E. & Villa, G. (1996). Oligocene-Miocene calcareous nannofossil biostratigraphy and paleoeecology from the Iberian Abyssal Plain. Proceedings of the Ocean Drilling Program, Scientific Results. 149: 79-145. gs V O

Deflandre, G. & Fert, C. (1954). Observations sur les coccolithophoridés actuels et fossiles en microscopie ordinaire et électronique. Annales de Paléontologie. 40: 115-176. gs

Fioroni, C., Villa, G., Persico, D., Wise, S. W. & Pea, L. (2012). Revised middle Eocene-upper Oligocene calcareous nannofossil biozonation for the Southern Ocean. Revue de Micropaléontologie. 55(2): 53-70. gs

Firth, J. V. & Wise, S. W. (1992). A preliminary study of the evolution of Chiasmolithus in the Middle Eocene to Oligocene of sites 647 and 748. Proceedings of the Ocean Drilling Program, Scientific Results. 120: 494-508. gs V O

Hay, W. W., Mohler, H. P. & Wade, M. E. (1966). Calcareous nannofossils from Nal'chik (northwest Caucasus). Eclogae Geologicae Helvetiae. 59: 379-399. gs V O

Perch-Nielsen, K. (1971c). Elektronenmikroskopische untersuchungen an Coccolithen und verwandten Formen aus dem Eozan von Danemark. Biologiske Skrifter, Kongelige Danske Videnskabernes Selskab. 18(3): 1-76. gs

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

Perch-Nielsen, K. (1985a). Cenozoic calcareous nannofossils. In, Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge 427-555. gs

Persico, D. & Villa, G. (2008). A new Eocene Chiasmolithus species: hypothetical reconstruction of its phyletic lineage. Journal of Nannoplankton Research. 30(1): 23-33. gs V O

Shamrock, J. L. & Watkins, D. K. (2012). Eocene calcareous nannofossil biostratigraphy and community structure from Exmouth Plateau, Eastern Indian Ocean (ODP Site 762). Stratigraphy. 9(1): 1-11. gs

Varol, O. (1998). Palaeogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 200-224. gs

Wei, W. & Wise, S. W. (1990b). Middle Eocene to Pleistocene calcareous nannofossils recovered by Ocean Drilling Program leg 113 in the Weddell Sea. Proceedings of the Ocean Drilling Program, Scientific Results. 113: 639-666. gs V O

Wise, S. W. (1983). Mesozoic and Cenozoic calcareous nannofossils recovered by DSDP Leg 71 in the Falkland Plateau region, Southwest Atlantic Ocean. Initial Reports of the Deep Sea Drilling Project. 71: 481-550. gs V O


Chiasmolithus oamaruensis compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 23-1-2021

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Comments (1)

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Juan P. Pérez Panera (Los Talas, Argentina)

Complete name of this species should be Chiasmolithus oamaruensis (Deflandre in Deflandre and Fert, 1954) Hay et al., 1966, to keep nannotax style.

Jeremy Young (Tonbridge, UK)

yes - indeed. I've changed that now, thanks Jeremy

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