Daughter taxa (time control age-window is: 0-800Ma)![]() | ||||
![]() | Amaurolithus brevigracilis Like A. delicatus but shorter arms. | |||
![]() | ![]() | Amaurolithus delicatus Simple horseshoe-shaped amauroliths. Grades into the other morphotypes, especially A. primus and A. tricorniculatus. | ||
![]() | Amaurolithus primus Simple form with short arms, broad arch and weakly developed keels. | |||
![]() | ![]() | Amaurolithus tricorniculatus Right arm extended into apical spur. | ||
Amaurolithus sp. Specimens which cannot be assigned to established species |
Taxonomy:
Distinguishing features:
Parent taxon (Ceratolithaceae): Horseshoe-shaped rod-shaped nannoliths and simple hoop-coccoliths formed in one phase of life cycle, planolith heterococcoliths in the other.
This taxon: Ceratoliths non-birefringent or only weakly birefringent
Farinacci & Howe catalog pages: Amaurolithus *
Morphology:
In the SEM Amaurolithus ceratoliths (sometimes termed amauroliths) usually come to rest with the more ornamented surface upward, in this orientation the left hand arm is distinctly curved whilst the right hand arm is relatively straight, but more heavily ornamented.
LITHS: nannolith-other, horseshoe-shaped, asymmetric, CROSS-POLARS: V-prominent, 1ou, |
Lith size: 5->12µm; Segments: 1->1; |
Geological Range:
Last occurrence (top): at top of NN14 zone (100% up, 3.9Ma, in Zanclean stage). Data source: Total of ranges of the species in this database
First occurrence (base): within NN11b subzone (6.91-7.42Ma, base in Tortonian stage). Data source: Total of ranges of species in this database
Plot of occurrence data:
Gartner, S. & Bukry, D. (1975). Morphology and phylogeny of the coccolithophycean family Ceratolithaceae. Journal of Research of the U.S. Geological Survey. 3: 451-465. gs Raffi, I., Backman, J. & Rio, D. (1998). Evolutionary trends of tropical calcareous nannofossils in the late Neogene. Marine Micropaleontology. 35(1): 17-41. gs Young, J. R. (1998). Neogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 225-265. gs References:
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Amaurolithus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 14-2-2025
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=40 Go to Archive.is to create a permanent copy of this page - citation notes |
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