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)
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
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)
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:
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:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Neptune data: This is a higher taxon page so Neptune data is not plotted. See also: customisable plot Parent: Nannoconaceae
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
Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 132-199. gsO
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. gsVO
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
Young, J. R. et al. (1997). Guidelines for coccolith and calcareous nannofossil terminology. Palaeontology. 40: 875-912. gsVO
Nannoconus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 29-5-2022
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