Asinithistimorfi aubryae

Bowman & Varol, 2021 Aug 14, 2019

Set number: 47

  • Asinithistimorfi paraxenos 56871 1
  • Asinithistimorfi paraxenos 56898 2
  • Asinithistimorfi paraxenos 56872 3
  • Asinithistimorfi paraxenos 56894 4
  • Asinithistimorfi paraxenos 56870 5
  • Asinithistimorfi paraxenos 56869 6
  • Asinithistimorfi paraxenos 56873 7
  • Asinithistimorfi paraxenos 56892 8
  • Asinithistimorfi paraxenos 56879 9
  • Asinithistimorfi paraxenos 56876 10
  • Asinithistimorfi paraxenos 56880 11
  • Asinithistimorfi paraxenos 56895 12
  • Asinithistimorfi paraxenos 56878 13
  • Asinithistimorfi paraxenos 56874 14
  • Asinithistimorfi paraxenos 56881 15
  • Asinithistimorfi paraxenos 56890 16
  • Asinithistimorfi paraxenos 56885 17
  • Asinithistimorfi paraxenos 56882 18
  • Asinithistimorfi paraxenos 56887 19
  • Asinithistimorfi paraxenos 56889 20
  • Asinithistimorfi paraxenos 56884 21
  • Asinithistimorfi paraxenos 56877 22
  • Asinithistimorfi paraxenos 56888 23
  • Asinithistimorfi paraxenos 56896 24
  • Asinithistimorfi paraxenos 56902 25
  • Asinithistimorfi paraxenos 56868 26
  • Asinithistimorfi paraxenos 56899 27
  • Asinithistimorfi paraxenos 56891 28
  • Asinithistimorfi paraxenos 56901 29
  • Asinithistimorfi paraxenos 56897 30
  • Asinithistimorfi paraxenos 56900 31
  • Asinithistimorfi paraxenos 56893 32
    10µm
Asinithistimorfi aubryae, Late Paleocene, DSDP Leg 36, Site 327A, The Maurice Ewing Bank, Falkland Plateau
Final Epithet
Asinithistimorfi aubryae Bowman & Varol, 2021
Basionym

Asinithistimorfi paraxenos Bowman & Varol, 2021

Diagnosis

Elliptical heliolith possessing two non-birefringent discs and a moderate-high column that appears hollow and closed by a distal plug. The diameter of the median disc is greater than the diameter of the proximal disc.

Etymology

In honour of renowned nannofossil specialist Dr M.-P. Aubry, seasoned nannofossil taxonomist and biostratigrapher.

Dimensions Of Holotype

Overall height: 4.21μm, Overall length: 8.33μm, Overall width: 4.21μm; Column height:1.93μm, Column length: 6.27μm, Column width: 5.44μm.

Description

Moderately large (6.0-9.0 µm) and elliptical heliolith comprised two discs and a column. The discs are of unequal diameter (i.e. the median disc is wider than the proximal disc) and appear flat to very slightly convex (observed in side-view). The distal plug appears rough and distinct. The discs and narrow central opening are visible under phase-contrast and bright-field settings (Plate 2, Figs. 20 and 24 in Bowman & Varol, 2021) in plan-view. The column and plug artificially resemble an overgrown Dictyococcites bisectus under polarised light.

Optical properties: In plan-view, the discs are non-birefringent, and the column is strongly birefringent. The entire species appears birefringent in the side-view. In cross-polarised light, the distal side shows a dextrogyre-type extinction pattern (e.g. Pl. 3, Figs. 10, 14 in Bowman & Varol, 2021). In contrast, the proximal side is characterised by a laevogyre-type extinction pattern (e.g. Pl. 3, Figs. 11, 15 in Bowman & Varol, 2021). When using the gypsum plate, with the species oriented in the north-south position, a distal view will show the blue regions corresponding to the horizontal axis. In contrast, a proximal view will show the blue sectors corresponding to the vertical axis.

Remarks

The elliptical shape and bizarre rough appearance of the column and plug (and unique form of species in general) are diagnostic identification features.

References

Bowman, A. R. & Varol, O. 2021. A Taxonomic Revision of Heliolithaceae - Applications in Resolving the Problematic Calcareous Nannofossil Biostratigraphy of the Paleocene. In: M. Montenary, M. (Ed.). Calcareous nannofossil biostratigraphy of the Stratigraphy and timescales. 6: 43-223.

Taxonomy
Asinithistimorfi
Biostratigraphy
  • Phanerozoic
    • Cenozoic
      • Paleogene
        • Paleocene
          • Late Paleocene
            • Thanetian
          • Middle Paleocene
            • Selandian
Stratigraphic Range
Selandian - Thanetian
Age (Ma)
60.29 - 57.24
Holotype
Asinithistimorfi paraxenos 56871 Asinithistimorfi paraxenos 56871

Asinithistimorfi aubryae Bowman & Varol, 2021

Late Paleocene

DSDP Leg 36, Site 327A, The Maurice Ewing Bank, Falkland Plateau