Nannotax3 - ntax_mesozoic - Micula murus

Micula murus


Classification: ntax_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:
Parent taxon (Micula): Typically cubiform nannoliths usually formed from two superimposed and complexly-intergrown cycles of four pyramidal/blocky elements each
This taxon: Micula in which one cycle 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:
Taxonomic discussion: Forms in which the upper cycle is greatly diminished were originally included in M. murus but are now are now placed in M. prinsii 

Farinacci & Howe catalog pages: T. murus *

Distinguishing features:
Parent taxon (Micula): Typically cubiform nannoliths usually formed from two superimposed and complexly-intergrown cycles of four pyramidal/blocky elements each
This taxon: Micula in which one cycle of four elements have protrusions extending tangentially from the corners of the cube


Morphology:

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.

Size:

Search data:
LITHS: nannolith-radiate, quadrate, star-shaped, CA: closed, CROSS-POLARS: T-prominent,
Lith size: 5->9µm; Segments: 4->4;
Data source notes: original description & illustrated specimens
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: Important marker for the Late Maastrichtian
Last occurrence (top): at top of Maastrichtian Stage (100% up, 66Ma, in Danian 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:

References:

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

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

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

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 V O

Manivit, H. (1989). Calcareous nannofossil biostratigraphy of Leg 108 sediments. Proceedings of the Ocean Drilling Program, Scientific Results. 108: 35-69. gs V O

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 V O

Perch-Nielsen, K. (1977a). 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 O

Perch-Nielsen, K. (1979d). Calcareous nannofossils from the Cretaceous between the North Sea and the Mediterranean. In, Weidmann, J. (ed.) Aspekte der Kreide Europas. International Union of Geological Sciences Series A. 6: 223-272. gs O

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. 31(1): 39-56. gs V O

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

Wise, S. W. & Wind, F. H. (1977). Mesozoic and Cenozoic calcareous nannofossils recovered by DSDP Leg 36 drilling on the Falkland Plateau, south-west Atlantic sector of the Southern Ocean. Initial Reports of the Deep Sea Drilling Project. 36(269-491): -. gs O


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Micula murus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 25-9-2022

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