Mesozoic Survivors

Classification: ntax_cenozoic -> Mesozoic Survivors
Sister taxa: Isochrysidales, Coccolithales, Zygodiscales, Syracosphaerales, Coccolith families inc sed, Mesozoic Survivors ⟩⟨ Holococcoliths, Braarudosphaerales, Discoasterales, Nannolith families inc sed, hidden

Daughter taxa (time control age-window is: 0-800Ma)Granddaughter taxa
Placoliths with two broad shields; central area narrow; distal shield formed from V-units; proximal shield and tube formed from R-units.

Loxolith coccoliths with variably-developed proximal/inner-cycles and a central-area spanned by axial, non-axial or diagonal crossbars or a single transverse bar. LM image includes both unicyclic and bicyclic types. Outer rim clockwise-imbricate.

Circular placoliths with moderately birefringent shields, bright inner tube cycle and narrow or closed central areas.

Placoliths or modified placoliths with R-unit well developed, forming proximal and distal shield elements with opposite senses of imbrication; the V-unit typically forms a narrow distal cycle near the inner edge of the shield. Central-area structures are typically disjunct. Birefringent LM image, in which the V-unit cycle appears only as a thin, dark line.


Citation: Mesozoic Survivors sensu Young & Bown, 1997
Rank: informal group of families
Taxonomic discussion: Mesozoic survivors are nannoplankton that survived the K-Pg mass extinction event 65.5 Ma. Many of these taxa are discussed in more depth in the Mesozoic section. Other survivor taxa include Calciosolenia and Braarudosphaera.

Distinguishing features: Mesozoic taxa which occur in low abundances in the early Palaeogene.

Farinacci & Howe catalog pages: Mesozoic Survivors [no catalog entry yet]

Phylogenetic relations: Useful discussion of the K/Pg extinctions effect on nannoplankton include: Bramlette & Martini (1964); MacLeod et al. (1997); Mai et al. (1997); Burnett (1998); Pospichal (1996); Bown (2005);Medlin et al. (2008);Jiang et al. (2010); Schulte et al. (2010);

See also: Braarudosphaera bigelowii ;Calciosolenia ;Cruciplacolithus primus - other Cretaceous survivors, in major groups;

Search data:
MetricsLith size: 3->13.5µm;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: Most of these taxa only occur in the Palaeocene, however, the Watznaueriacean cocolith Tergestiella adriatica is now known to still be extant (Hagino et al. 2015).
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): in upper part of Bajocian Stage (81% up, 168.7Ma, in Bajocian stage). Data source: Total of range of species in this database

Plot of occurrence data:


Bown, P. R. (2005e). Selective calcareous nannoplankton survivorship at the Cretaceous-Tertiary boundary. Geology. 33(8): 653-656. gs

Bramlette, M. N. & Martini, E. (1964). The great change in calcareous nannoplankton fossils between the Maestrichtian and Danian. Micropaleontology. 10(2): 291-322. gs

Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 132-199. gs V O

Hagino, K. et al. (2015). Re-discovery of a “living fossil” coccolithophore from the coastal waters of Japan and Croatia. Marine Micropaleontology. 116(1): 28-37. gs

Jiang, S., Bralower, T. J., Patzkowsky, M. E., Kump, L. R. & Schueth, J. D. (2010). Geographic controls on nannoplankton extinction across the Cretaceous/Palaeogene boundary. Nature Geoscience. 3(4): -. gs

MacLeod, N. et al. (1997). The Cretaceous-Tertiary biotic transition. Journal of the Geological Society of London. 1254(265-293): -. gs

Mai, H., von Salis, K., Willems, H. & Romein, A. J. T. (1997a). Fossil coccospheres from the K/T boundary section from Geulhemmerberg, The Netherlands. Micropaleontology. 43(281-302): -. gs

Medlin, L. K., Sáez, A. G. & Young, J. R. (2008). A molecular clock for coccolithophores and implications for selectivity of phytoplankton extinctions across the K/T boundary. Marine Micropaleontology. 67(1-2): 69-86. gs

Pospichal, J. J. (1996c). Calcareous nannoplankton mass extinction at the Cretaceous/Tertiary boundary: An update, in Ryder, G., et al., eds., The Cretaceous-Tertiary event and other catastrophes in Earth history. Geological Society of America, Special Papers. 307: 335-360. gs

Schulte, P. et al. (2010). The Chicxulub asteroid impact and mass extinction at the Cretaceous-Paleogene boundary. Science. 327: 1214-1218. gs

Young, J. R. & Bown, P. R. (1997a). Cenozoic calcareous nannoplankton classification. Journal of Nannoplankton Research. 19(1): 36-47. gs V O


Mesozoic Survivors compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 13-6-2021

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