Daughter taxa (time control age-window is: 0-800Ma) | Granddaughter taxa | ||||
Bomolithus Discoidal discoasteralids with a wide non-birefringent cycle and at least one narrower birefringent cycle, i.e., narrower than the diameter of the nannolith. | Bomolithus aquilus Bomolithus bramlettei Bomolithus conicus Bomolithus elegans Bomolithus megastypus Bomolithus supremus Bomolithus sp. | ||||
Heliolithus Discoidal discoasteralids formed of two superposed birefringent cycles. | Heliolithus kleinpellii Heliolithus bukryi Heliolithus cantabriae Heliolithus knoxii Heliolithus riedelii Heliolithus aktasii Heliolithus sp. |
Taxonomy:
Distinguishing features:
Parent taxon (Discoasterales): Radially symmetrical nannoliths formed from one to several separate cycles of elements that radiate from a common centre or axis.
This taxon: Discoidal discoasteralids with several distinct cycles including at least one that is birefringent.
Original description: Diagnosis - Coccoliths composed of two abbuting shields lacking a connecting tube; one shield having subradial sutures, producing a strong interference pattern between crossed polarizers; the other shield somewhat 'smaller, showing steeply inclined sutures and strongly imbricate segments.
Farinacci & Howe catalog pages: Heliolithaceae *
Search data:
Lith size: 5->18µm; |
Geological Range:
Last occurrence (top): at top of NP9b subzone (100% up, 55.9Ma, in Ypresian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within NP5 zone (59.54-61.51Ma, base in Selandian stage). Data source: Total of ranges of species in this database
Plot of occurrence data:
Hay, W. W. & Mohler, H. P. (1967). Calcareous nannoplankton from Early Tertiary rocks at Point Labau, France and Paleocene-Early Eocene correlations. Journal of Paleontology. 41(6): 1505-1541. gsReferences:
Heliolithaceae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 14-12-2024
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=697 Go to Archive.is to create a permanent copy of this page - citation notes |
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