Nannotax Enabling nannofossil research

Description: Holococcoliths are formed of numerous minute rhombohedral calcite crystallites. They are produced during the haploid phase of the life cycle of a wide range of  coccolithophores which bear heterococcoliths in their  diploid life-cycle phase.

Remarks: Although diverse holococcolith asemblages have been described from Cretaceous and Palaeogene assemblages they are virtually absent in Neogene nannofloras. Tis is raher surprisinggiven that modern nannofloras include >60 holococcolithophores (see e.g. Kleijne, 1991, Jordan and Kleijne, 1994, Young et al. 2003), but most species produce very small holococcoliths (often <2μm) with low preservation potential.

Only the relatively few holococcoliths with a reasonable Neogene fossil record are included here. Where the heterococcolith phase is known the taxonomy has been adjusted, as reccomended by Thomsen et al. (1991), Cros et al. (2000) and Young et al. (2003).     

Range: Mesozoic to Recent

Synonym: Family CALYPTROSPHAERACEAE Boudreaux and Hay, 1969. It used to be conventional to place all holococcoliths in the famly Calyptrosphaeraceae, however this is manifestly artificail since it is now known that holocoliths are formed during the haploid life-cycle stage of species belonging to numerous different families. Moreover the type species of the family Calyptrosphaeceae, Calytrosphaera oblonga is now known to be a life-cyle phase of Syracosphaera pulchra, hence the name Calytrosphaeraceae is a junior synonym of Syracosphaeraceae.