Distinguishing features: Parent taxon (Watznaueriales): Placolith (or modified placolith) coccoliths with a distal cycle of clockwise-imbricating elements. R-units well developed, forming proximal and distal shield elements with opposite senses of imbrication; V-units typically form a narrow distal cycle near the inner edge of the shield. This taxon: Placoliths or modified placoliths with R-unit well developed, forming proximal and distal shield elements with opposite senses of imbrication; the V-unit typically forms a narrow distal cycle near the inner edge of the shield. Central-area structures are typically disjunct. Birefringent LM image, in which the V-unit cycle appears only as a thin, dark line.
Daughter taxa (time control age-window is: 0-800Ma)
Granddaughter taxa
Regular placoliths
Bussonius Elliptical watznaueriacean coccoliths with broad V-unit cycle, which results in a three tiered placolith structure. Moderately birefringent in XPL.
Diazomatolithus Modified watznaueriacean coccoliths with one conical/flaring (proximal) shield with elements joined along oblique sutures, and a smaller, flatter (distal) shield with the principle elements joined along near radial sutures. Usually circular with a central opening.
Lotharingius Elliptical watznaueriacean coccoliths typically with central-area axial cross, with or without additional lateral bars. Cross usually spine bearing. Extinction figure with nearly straight arms.
Watznaueria Elliptical watznaueriacean coccoliths with central-areas that are typically closed or narrow but may be spanned by transverse bar, bars or grill. Extinction figure with clearly inflected arms.
Bibreviconus High, cylindrical morphology with a peg-like distal cycle; possibly the isolated central part of Cyclagelosphaera deflandrei specimens which have lost the shields.
Distinguishing features: Parent taxon (Watznaueriales): Placolith (or modified placolith) coccoliths with a distal cycle of clockwise-imbricating elements. R-units well developed, forming proximal and distal shield elements with opposite senses of imbrication; V-units typically form a narrow distal cycle near the inner edge of the shield. This taxon: Placoliths or modified placoliths with R-unit well developed, forming proximal and distal shield elements with opposite senses of imbrication; the V-unit typically forms a narrow distal cycle near the inner edge of the shield. Central-area structures are typically disjunct. Birefringent LM image, in which the V-unit cycle appears only as a thin, dark line.
Morphology: Coccoliths are highly birefringent in XPL. Common, sometimes dominant, through most of the Mesozoic (Pliensbachian to Maastrichtian).
Search data:
Tags
LITHS: placolith,
Metrics
Lith size: 0->0µm;
The morphological data given here can be used on the advanced search page. See also these notes
Geological Range: Last occurrence (top): in lower part of Ypresian Stage (22% up, 54.2Ma, in Ypresian stage). Data source: Total of range of species in this database First occurrence (base): at base of Pliensbachian Stage (0% up, 190.8Ma, in Pliensbachian stage). Data source: Total of range of species in this database
Plot of occurrence data:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Neptune data: this is a higher taxon page so Neptune data is not plotted. For the customisable plot option go to a genus page Parent: Watznaueriales
References:
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
Reinhardt, P. (1964). Einige Kalkflagellaten-Gattungen (Coccolithophoriden, Coccolithineen) aus dem Mesozoikum Deutschlands. Monatsberichte der Deutschen Akademie der Wissenschaften zu Berlin. 6: 749-759. gsVO
Rood, A. P., Hay, W. W. & Barnard, T. (1971). Electron Microscope Studies of Oxford Clay Coccoliths. Eclogae Geologicae Helvetiae. 64: 245-272. gsVO
Watznaueriaceae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 18-10-2021
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