Nannotax3 - ntax_mesozoic - Nannoconus

Nannoconus


Classification: ntax_mesozoic -> Braarudosphaerales -> Nannoconaceae -> Nannoconus
Sister taxa: Faviconus, Nannoconus

Distinguishing features:
Parent taxon (Nannoconaceae): Conical, globular or cylindrical nannoliths composed of plates spirally-arranged around an axial cavity or canal. Plate c-axes are arranged tangentially to the longitudinal axis.
This taxon: Conical, globular or cylindrical nannoliths composed of plates spirally-arranged around an axial cavity (~>1µm in width) or canal (~<1µm in width). Plate c-axes are arranged tangentially to the longitudinal axis.


Daughter taxa (time control age-window is: 0-800Ma)Granddaughter taxa
N. steinmannii group
Tapering nannoconids with narrow central canal (ct < wt).
Nannoconus bermudezii
Nannoconus dolomiticus
Nannoconus farinacciae
Nannoconus regularis
Nannoconus steinmannii

N. kamptneri group
Pear-shaped and tapering nannoconids with wide central cavity (ct = 1-3 x wt).

N. abundans group
Cylindrical nannoconids with thin, low-angled wall cycles and relatively narrow canal (ct < wt); also may have apical and/or antapical flanges and/or bulbous base
Nannoconus abundans
Nannoconus alvus
Nannoconus borealis
Nannoconus concavus
Nannoconus inornatus
Nannoconus troelsenii

N. truittii group
Cylindrical, barrel-shaped or slightly tapering nannoconids with moderately wide central canals (ct ≈ wt).

N. circularis group
Cylindrical nannoconids with thin walls (~1.5µm or less), thin, low-angled wall cycles and very wide central cavity (typically ct >3x wt)
Nannoconus carniolensis
Nannoconus circularis
Nannoconus fragilis
Nannoconus grandis
Nannoconus quadratus

N. compressus group
Relatively small (<~5µm), subcircular, elliptical or cylindrical nannoconids with relatively narrow canals (ct < wt).
Nannoconus compressus
Nannoconus infans
Nannoconus puer

Nannoconus - atypical
Atypical nannoconids, not fitting in any of the main groups
Nannoconus funiculus
Nannoconus ligius
Nannoconus magnadiscus
Nannoconus nicholasii
Nannoconus pseudoseptentrionalis
Nannoconus sabinae

Nannoconus sp.
Specimens not identified to species level

Taxonomy:

Citation: Nannoconus Kamptner, 1931
Rank: Genus
Type species: Nannoconus steinmannii Kamptner, 1931
Synonyms: Brachiolithus Noël (1959)
Nannosphaeroidina Colom 1968

Farinacci & Howe catalog pages: Nannoconus + + * , Brachiolithus * , Nannosphaeroidina *

Distinguishing features:
Parent taxon (Nannoconaceae): Conical, globular or cylindrical nannoliths composed of plates spirally-arranged around an axial cavity or canal. Plate c-axes are arranged tangentially to the longitudinal axis.
This taxon: Conical, globular or cylindrical nannoliths composed of plates spirally-arranged around an axial cavity (~>1µm in width) or canal (~<1µm in width). Plate c-axes are arranged tangentially to the longitudinal axis.


Morphology:

Nannoconids are particularly common in early Cretaceous Tethyan carbonates. Following abundance declines in the late Barremian to early Aptian they are only occassionally common in younger levels and became extinct in the Campanian. They can be difficult to work with and classify due to intraspecific variability, problems related to microscopical resolution of globose, three-dimensional objects, and poor preservation in the Tethyan limestones, where nannoconids are most common and from which most holotypes were figured. These problems, together with complex palaeobiogeographic patterns, have resulted in rather poor calibration of nannoconid bioevents. For an explanation of general nannoconid morphology and terminology see van Niel (1993, 1994) and Young et al. (1997).

Size:


Ecology & Biogeography


Biology & life-cycles

Phylogenetic relations

Search data:
LITHS: nannolith-radiate, circular, cylindrical, hollow, CA: vacant, CROSS-POLARS: T-prominent,
Lith size: 3->55µm;
Data source notes: size range of included species
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): at top of Campanian Stage (100% up, 72.1Ma, in Campanian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Tithonian Stage (0% up, 152.1Ma, in Kimmeridgian 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. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 34-85. gs O

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

Kamptner, E. (1931). Nannoconus steinmanni novo gen., novo spec., ein merkwurdiges gesteinbildendes Mikrofossil aus dem jungeren Mesozoikum der Alpen. Paläontologische Zeitschrift. 13: 288-298. gs

van Niel, B. E. (1992). New observations on the morphology of Nannoconus. In, Hamrsmid, B. & Young, J. R. (eds) Nannoplankton Research, Proceedings of the 4th INA Conference, Prague 1991, vol II. Knihovnicka ZPN . 14a: 73-85. gs V O

van Niel, B. E. (1994a). A review of the terminology used to describe the genus Nannoconus (calcareous nannofossil, incertae sedis). Cahiers de Micropaléontologie. 9: 27-47. gs V O

Young, J. R. et al. (1997). Guidelines for coccolith and calcareous nannofossil terminology. Palaeontology. 40: 875-912. gs V O


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Nannoconus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 26-11-2022

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10718 Go to Archive.is to create a permanent copy of this page - citation notes



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