Mesozoic Survivors


Ancestry: Coccolithophores -> Mesozoic Survivors
Sister taxa: Isochrysidales, Coccolithales, Zygodiscales, Syracosphaerales, Coccolith families inc sed, Holococcoliths, Discoasterales, Nannolith families inc sed, Mesozoic Survivors, hidden,

Short diagnosis: Mesozoic taxa which occur in low abundances in the early Palaeogene.


Daughter taxa (blue => in age window 0-300Ma) 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.

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.

Taxonomy:

Citation: Mesozoic Survivors sensu Young & Bown, 1997
Rank: informal group
Notes & 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.

Farinacci & Howe catalog pages:

Short diagnosis: Mesozoic taxa which occur in low abundances in the early Palaeogene.


Evolution & Phylogeny: 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;

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): within Bajocian Stage (168.28-170.30Ma, base in Bajocian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

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

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

Burnett, J.A., (1998). Upper Cretaceous. In: Bown, P.R. (Editor), Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publications Series. Chapman & Hall, London, pp. 132-199.

Hagino, K.; Young, J.R.; Bown, P.R.; Godrijan, J.; Kulhanek, D.K.; Kogane, K. & Horiguchi, T., (2015). Re-discovery of a “living fossil” coccolithophore from the coastal waters of Japan and Croatia. Marine Micropaleontology, 116(1): 28-37.

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).

MacLeod, N. & others, (1997). The Cretaceous-Tertiary biotic transition. Journal of the Geological Society of London, 1254(265-293).

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

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.

Pospichal, J.J., (1996). 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 Paper, 307: 335-360.

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

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


Nannotax3 - Coccolithophores - Mesozoic Survivors by: Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 24-3-2017

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