The Braarudosphaeraceae are an enigmatic group of nannoliths ranging from the Early Cretaceous to the present day. Despite being extant they have never been succesfully cultured and so their afinities are uncertain (they may be Haptophytes, Dinophytes or belong to another group). They are of minimal biostratigraphic value but occasionally occur in enormous abundance, most notably in the Early Danian just after the K/T boundary and in the Oligocene of the South Atlantic.
Update: Although Braarudosphaera has still not been succesfully cultured, despite repeated attempts, Takano et al. (2006) have obtained DNA sequences from single-cell isolations. These showed that Braarudosphaera is a haptophyte and falls inside the coccolithophore clade.

Informal taxon-based term: Pentalith {Gran and Braarud 1935} - nannolith formed by the Braarudosphaeraceae (N.B. does not include other nannoliths formed of five elements, such as Discoaster pentaradiatus).
Lamina plate-like sub-element of segments.
Segment one of the five component parts of a pentalith. They appear to be single crystal-units, with tangential c-axis orientation.

Return to terminology index