Type Species

Coccolithus cuvillieri Manivit, 1966

Description

Placoliths are constructed of a broad cretarhabdid pelaga sloping towards the central area, formed of inclined segments that are typically weakly clockwise-imbricated, rarely lacking imbrication, and a distally arched central area characterised by a fibrous axial cross supporting a solid distal process. The intercross area is occupied by non-permanent lateral bars, visible only in well-preserved specimens.

The arms of the axial cross are composed of three rows of longitudinal segments.

Optical Properties

In plan view under crossed polars, the pelaga exhibits slightly greyish-white interference colours with length-fast (–) elongation.

In the axial cross, the median row of longitudinal segments displays optical properties distinct from those of the adjacent rows: the median row shows constant extinction, whereas the bordering rows exhibit white interference colours with length-slow (+) elongation.

References

Manivit, H. 1966. Sur quelques coccolithes nouveaux du Néocomien. Compte Rendu Sommaire des Séances de la Société Géologique de France. 7: 267-268.

Thierstein, H. R., 1971. Tentative Lower Cretaceous Calcareous Nannoplankton Zonation. Eclogae Geologicae Helvetiae 64, 459-488.