Daughter taxa (time control age-window is: 0-800Ma)
sub-axial cross-bars
Neochiastozygus denticulatus Small Neochiastozygus with asymmetric cross bars and additional lateral bars that are visible as a plate-like image in XPL.
Neochiastozygus eosaepes Small Neochiastozygus with non-imbricate outer wall cycle. The diagonal cross is slightly rotated.
Neochiastozygus imbriei Small Neochiastozygus with asymmetric cross bars rotated from axial by 10-20°.
Neochiastozygus tenansa Small, elliptical Neochiastozygus, with central cross that is only slightly oblique to the major and minor axes.
diagonal cross-bars
Neochiastozygus concinnus Medium to large with diagonal cross with bars that do not flare at their ends. Cross bars make an angle of ~40°.
Neochiastozygus digitosus Small, narrowly-elliptical Neochiastozygus with curving, high-angle slightly asymmetric cross-bars - offset where they meet. Grill at base of central area
Neochiastozygus distentus Medium-sized Neochiastozygus with narrow central area filled with diagonal cross bars that are embedded into the rim.
Neochiastozygus modestus Small Neochiastozygus with relatively small central area and broad bars which may be slightly rotated. Bright inner rim cycle prominent in XPL.
Neochiastozygus pusillus Small, narrowly-elliptical Neochiastozygus with a bicyclic XPL image and curving, high-angle cross-bars that are slightly asymmetric and offset where they meet.
Neochiastozygus saepes Medium-sized, narrowly elliptical Neochiastozygus with prominent bright inner cycle in XPL and broad cross bars.
Neochiastozygus substrictus Medium sized, narrowly elliptical Neochiastozygus with a slightly asymmetrical diagonal cross. Cross bars make an angle of 30-40°.
transverse cross-bars
Neochiastozygus junctus Large Neochiastozygus with diagonal cross bars that form an angle of ~20°.
Neochiastozygus macilentus Medium to large Neochiastozygus with narrow rim and wide central area spanned by narrow cross bars that make an angle of ~30°.
Neochiastozygus perfectus Medium-sized Neochiastozygus with relatively wide central area and straight, narrow bars that meet at a narrow angle.
Neochiastozygus rosenkrantzii Medium-sized Neochiastozygus with broad diagonal cross bars that flare at their ends. Cross bars make an angle of ~40°.
Neochiastozygus sp. Specimens which cannot be assigned to any established species
van Heck & Prins 1987 fig16-neochiastozygus.png
Taxonomy:
Citation: Neochiastozygus Perch-Nielsen, 1971taxonomic rank: GenusType species: Neochiastozygus perfectus Perch-Nielsen 1971Synonyms: Corbilithus Haq 1971 - the type species of Corbilithus, Zygolithus tenansa was transferred to Neochiastozygus by Self-Trail (2011)
Distinguishing features: Parent taxon (Zygodiscaceae): Muroliths with rim formed from well-developed V- and variably developed R-units, with opposite imbrication directions, and central area structures that include disjunct transverse bars and diagonal crosses. R-units vestigial or not observed in several genera (Chiphragmalithus, Isthmolithus, Neococcolithes). This taxon: Muroliths with well-developed V- and R-units and diagonal or asymmetric cross in central-area.
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 Oligocene Epoch (100% up, 23Ma, in Aquitanian stage). Data source: Total of ranges of the species in this database First occurrence (base): within NP1 zone (65.47-66.04Ma, base in Danian stage). Data source: Total of ranges 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: Zygodiscaceae
References:
Perch-Nielsen, K. (1971d). Neue Coccolithen aus dem Paläozän von Dänemark, der Bucht von Biskaya und dem Eozän der Labrador See. Bulletin of the Geological Society of Denmark. 21: 51-66. gs
Perch-Nielsen, K. (1985). Cenozoic calcareous nannofossils. In, Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge (1): 427-555. gs
van Heck, S. E. & Prins, B. (1987). A refined nannoplankton zonation for the Danian of the Central North Sea. Abhandlungen der Geologischen Bundesanstalt. 39: 285-303. gs
Neochiastozygus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 19-9-2024
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