Micula adumbrata


Classification: Mesozoic -> Braarudosphaerales -> Polycyclolithaceae -> Micula -> Micula adumbrata
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: Like M. staurophora but with atypical structure, possible ancestral


Taxonomy:

Citation: Micula adumbrata Burnett, 1997
Rank: Species

Farinacci & Howe catalog pages: M. adumbratus *

Distinguishing features: Like M. staurophora but with atypical structure, possible ancestral


Morphology remarks:
"In plan view in the LM, the new species appears similar to M. staurophora in one orientation but when rotated reveals a more complex morphology than the triangular blocks which comprise M. staurophora. It is difficult to discern whether the sutures between the constituent blocks of the new species cut the corners of a square (as in Micula) or the edges (as in Quadrum). In PC, there appear to be four smaller blocks situated between and/or below the main, highly birefringent ones which provide the Micula-like form." [Burnett 1997]

Evolution & Phylogeny: This new species is believed to constitute an intermediate form between Quadrum and Micula but is placed in Micula because it occurs just below the FO of M staurophora and because its interference figure is reminiscent of this species. The form is dissimilar to any species of Quadrum (compare with Varol's (1992) plates 6 and 7). [Burnett 1997]

Search data:
Tagsnannolith-radiate, quadrate, CA: closed,
MetricsLith size: 4->6µm; Segments: 4->4;
Data source notes: original description & illustrated specimens
Sources: original description & illustrated specimens
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within Coniacian Stage (86.26-89.77Ma, top in Coniacian stage). Data source: Burnett 1998
First occurrence (base): in upper part of UC9c subzone (70% up, 89.8Ma, in Turonian stage). Data source: Burnett 1998, fig 6.4

Plot of occurrence data:

References:

Burnett, J. A. (1997c). New species and new combinations of Cretaceous nannofossils and a note on the origin of Petrarhabdus (Deflandre) Wise & Wind. Journal of Nannoplankton Research. 19(2): 133-146. 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 V 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


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Micula adumbrata compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 25-9-2020

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10674 Go to Archive.is to create a permanent copy of this page - citation notes



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