Mesozoic


Ancestry: Mesozoic
Sister taxa:

Short diagnosis: Mesozoic nanofossils - Cenozoic and extant taxa are in a separate module


Daughter taxa (blue => in age window 0-300Ma) Granddaughter taxa
Tiered placoliths with 3-5 closely appressed shields.

Murolith coccoliths with a distal/outer cycle of clockwise imbricating elements

Muroliths with a distal/outer-cycle of non-imbricating elements, i.e. in side view, the sutures are vertical or near vertical.

Placolith (or modified placolith) coccoliths; shield elements display little or no imbrication; typically V- units form distal shield, R units form proximal shield

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.

Nannofossils which show neither the rim structure of heterococcoliths nor the microcrystal structure of holococcoliths.

Coccoliths formed of minute (ca 0.1µm) rhombohedral microcrytals.

Heterococcolith genera which do not show characteristic features of any of the well-established families.

Calcispheres and other non-coccoliths found in nannofossil preps. Some taxa previously placed here have been moved to the calcareous dinoflagellates [Feb 2017]. 

Taxonomy:

Notes & discussion: The Cretaceous/Paleogene extinctions had a massive effect on calcareous nannofossils with virtually all common species becoming extinct, hence it is convenient to treat Mesozoic and Cenozoic nannoplankton separately. They are not, however, phylogenetically separate groups since there are significant common features between them (e.g. V and R mode calcification in heterococcoliths, Young et al. 1991), and since it is commonly accepted that the Cenozoic orders each originated, separately, from Mesozoic precursors (e.g. Perch-Nielsen 1979, Medlin et al. 2008).
The most important overviews of Mesozoic nannofossils are given by Perch-Nielsen (1985) and in the various chapters in Bown (1998). In addition Bown & Young (1997) introduce the taxonomy used in Bown (1998), and we largely follow that taxonomy here.

Farinacci & Howe catalog pages:

Short diagnosis: Mesozoic nanofossils - Cenozoic and extant taxa are in a separate module

Geological Range:
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): within No known fossil record modern (0.00-0.00Ma, base in stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Bown, P.R. & Cooper, M.K.E., (1998). Jurassic. In: Bown, P.R. (Editor), Calcareous nannofossil biostratigraphy. British Micropalaeontological Society Publication Series. Chapman & Hall, pp. 34-85.

Bown, P.R. & Young, J.R., (1997). Mesozoic calcareous nannoplankton classification. Journal of Nannoplankton Research, 19(1): 21-36.

Bown, P.R., (1998). Triassic. In: Bown, P.R. (Editor), Calcareous nannofossil biostratigraphy. British Micropalaeontological Society Publication Series. Chapman & Hall, pp. 29-33.

Bown, P.R.; Rutledge, D.C.; Crux, J.A. & Gallagher, L.T., (1998). Early Cretaceous. In: Bown, P.R. (Editor), Calcareous nannofossil biostratigraphy. British Micropalaeontological Society Publication Series. Chapman & Hall, pp. 86-131.

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.

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.

Perch-Nielsen, K., (1979). Calcareous nannofossils from the Cretaceous between the North Sea and the Mediterranean. Aspekte der Kreide Europas, IUGS Series A, 6: 223-272.

Perch-Nielsen, K., (1985). Mesozoic calcareous nannofossils. In: Bolli, H.M., Saunders, J.B. and Perch-Nielsen, K. (Editors), Plankton Stratigraphy. Cambridge University Press, Cambridge, pp. 329-426.

Young, J.R.; Didymus, J.M.; Bown, P.R.; Prins, B. & Mann, S., (1992). Crystal assembly and phylogenetic evolution in heterococcoliths. Nature, 356: 516-518.


Nannotax3 - Mesozoic - Mesozoic by: Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 26-2-2017

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