Micula murus


Classification: Mesozoic -> Braarudosphaerales -> Polycyclolithaceae -> Micula -> Micula murus
Sister taxa: M. staurophora, M. adumbrata, M. concava, M. cubiformis, M. swastica, M. murus, M. prinsii, M. clypeata, M. praemurus, M. premolisilvae, M. sp.,

Distinguishing features: Micula in which one cyle of four elements have protrusions extending tangentially from the corners of the cube


Taxonomy:

Citation: Micula murus (Martini, 1961) Bukry, 1973
Rank: Species
Basionym: Tetralithus murus Martini, 1961
Synonyms: Micula mura (murus is a noun so does not change gender)
Notes & discussion: Forms in which the upper cycle is greatly diminished were orignially included in M. murus but are now are now placed in M. prinsii 

Farinacci & Howe catalog pages: Tetralithus murus *

Distinguishing features: Micula in which one cyle of four elements have protrusions extending tangentially from the corners of the cube


Morphology remarks: The nannolith is composed of two superimposed and complexly-intergrown cycles, one reduced in size, and each cycle twisting in opposite directions. For orientation the cycle of extended elements can be defined as at the bottom/basal. 
In plan view the elements are broadly triangular in shape, and point/twist consistently in one direction; the elements protrude significantly away from the edges of the cube. 
In side view M. murus appears thinner than in plan view, and the two superimposed cycles are of different size.

Geological Range:
Notes: Important marker for the Late Maastrichtian
Last occurrence (top): at top of Maastrichtian Stage (100% up, 66Ma, in Maastrichtian stage). Data source: Lees & Bown 2005 - consistently present to end Cret
First occurrence (base): at base of UC20b subzone (0% up, 69Ma, in Maastrichtian stage). Data source: Burnett 1998 (subzonal marker)

Plot of occurrence data:

  • Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
  • Note to users in China - the diagram may not plot unless you use a VPN since I use google services on the website. If this is a problem please contact me 谢谢.
  • Taxon plotted: Micula murus, synonyms included - Micula mura; Micula murus; Tetralithus murus;
  • space-time plot :: Samples map :: Parent: Micula

    References:

    Bukry, D. (1973d). Phytoplankton stratigraphy, Deep Sea Drilling Project Leg 20, Western Pacific Ocean. Initial Reports of the Deep Sea Drilling Project. 20: 307-317. gs

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

    Lees, J. A. & Bown, P. R. (2005). Upper Cretaceous calcareous nannofossil biostratigraphy, ODP Leg 198 (Shatsky Rise, Northwest Pacific Ocean). Proceedings of the Ocean Drilling Program. Scientific Results. 198: 1-60. gs

    Martini, E. (1961). Nannoplankton aus dem Tertiär und der obersten Kreide von SW-Frankreich. Senckenbergiana Lethaea. 42: 1-32. gs

    Müller, C. (1974b). Calcareous nannoplankton, Leg 25 (Western Indian Ocean). Initial Reports of the Deep Sea Drilling Project. 25: 579-633. gs

    Perch-Nielsen, K. (1977). Albian to Pleistocene calcareous nannofossils from the Western South Atlantic, DSDP Leg 39. Initial Reports of the Deep Sea Drilling Project. 39: 699-823. gs

    Perez-Rodriguez, I., Lees, J. A., Larasoaña, J. C., Arz, J. A. & Arenillas, I. (2012). Planktonic foraminiferal and calcareous nannofossil biostratigraphy and magnetostratigraphy of the uppermost Campanian and Maastrichtian at Zumaia, northern Spain. Cretaceous Research. 37: 100-126. gs

    Sissingh, W. (1977). Biostratigraphy of Cretaceous calcareous nannoplankton. Geologie en Mijnbouw. 65(1): 37-65. gs

    Thibault, N. (2010). Calcareous nannofossils from the boreal Upper Campanian- Maastrichtian chalk of Denmark. Journal of Nannoplankton Research. 30(1): 39-56. gs

    Varol, O. (1992b). Taxonomic revision of the Polycyclolithaceae and its contribution to Cretaceous biostratigraphy. Newsletters on Stratigraphy. 27(93-127): -. gs


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    Micula murus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 11-11-2019

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