Nannotax Enabling nannofossil research

Description: Coccolith rim structure similar to that of Coccolithus, but usually wider central area spanned by disjunct axial cross that may be rotated by up to 20 degrees.

Remarks: The classification of Paleogene Coccolithaceae coccoliths is problematical because of the presence of central area cross-bars across generic groupings (in particular Cruciplacolithus, Coccolithus and Chiasmolithus) that are supposedly characterized by the presence or absence of such bars or particular orientations of bars. Cruciplacolithus is typically defined as having a wide central area spanned by disjunct cross bars that are axially orientated or rotated by up to 20 degrees. Chiasmolithus tends to be used where the cross bars are diagonal.

Cruciplacolithus is not usually recorded in the post-Paleocene fossil record but they are present in well-preserved Eocene samples, and Bramletteiusis a closely related Eocene-Oligocene taxon.

Type species: Cruciplacolithus tenuis (Stradner, 1961). [Heliorthus]