Distinguishing features: Parent taxon (Kamptneriaceae): Arkhangelskielids with shields predominantly formed of V-units, thus dark in cross-polarised light; R-units form bright band at core of shield. This taxon: Tiered coccoliths with distinctive LM images consisting of a narrow to moderately-broad rim with a narrow, dark outer-cycle; a diagnostic, bright median-cycle; and a dark, inner-cycle. Central-area structures variable but generally dark in LM.
Daughter taxa (time control age-window is: 0-800Ma)
Granddaughter taxa
Species with plate in central area
Gartnerago obliquum Gartnerago with a narrow rim and a broad central area, filled with a plate pierced by numerous pores (~>10 in each quadrant); the plate is crossed by sutures, the transverse of which is slightly oblique.
Gartnerago diversum Gartnerago with protruding axial bars; perforations small, with a double row of perforations on each side of the cross-bars, with others randomly distributed
Species with narrow rim and solid plate
Gartnerago stenostaurion Small to large coccoliths characterized under LM XPL by a conspicuous, narrow, bright rim cycle and wide central area spanned by a plate. The plate is usually crossed by four radial extinction lines (two in the major axes of the coccolith ellipse and two diagonally orientated) and narrow, bright, bar-like structures, which are longitudinal and near transverse (rotated by ~10°), and birefringent when the coccolith is at 45° to the polarizing directions.
Gartnerago clarusora Central plate of 4 units with axial sutures, no axial cross; small (4-6 µm)
Gartnerago praeobliquum Gartnerago with wide central area spanned by broad axial cross bars that have arrowhead-shaped ends and median suture lines.
Species with transverse bar
Gartnerago coxalliae Central area, wide, open and spanned by a complex transverse bar, which bifurcates where it joins the rim.
Gartnerago nanum Medium-sized Gartnerago with a loxolith-type rim and a narrow, perforate central area plate, which has differentiated axial bars, although the longitudinal bar may be subordinate or poorly defined.
Gartnerago ponticula Small- to medium-sized (usually <7.0 µm) Gartnerago species with an open central area spanned by a transverse, conjunct bar.
Gartnerago theta Gartnerago with a wide central area spanned by a narrow transverse bar which delimits two, large D-shaped openings; a finely perforate proximal net is seen in good preservation (Black, 1975, Pl. 34, figs 6-8).
Gartnerago sp. Specimens not identified to species level
Taxonomy:
Citation: Gartnerago Bukry, 1969taxonomic rank: GenusType species: Arkhangelskiella concava Gartner, 1968; this is almost certainly a junior synonym of Gartnerago segmentatum (Stover, 1966), which therefore, by priority, becomes the type species.Synonyms: Cribricatillus Black, 1973; Laffittius Noël, 1969
Distinguishing features: Parent taxon (Kamptneriaceae): Arkhangelskielids with shields predominantly formed of V-units, thus dark in cross-polarised light; R-units form bright band at core of shield. This taxon: Tiered coccoliths with distinctive LM images consisting of a narrow to moderately-broad rim with a narrow, dark outer-cycle; a diagnostic, bright median-cycle; and a dark, inner-cycle. Central-area structures variable but generally dark in LM.
Morphology: Central-area structures include transverse bars, axial or diagonal cross bars (proximally-situated fine nets may be seen when preservation is good), or plates that are usually perforate, with axial or near axial sutures.
Lith size: 4->12µm; 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 Maastrichtian Stage (100% up, 66Ma, in Danian stage). Data source: Total of ranges of the species in this database First occurrence (base): within Late Aptian Substage (113.20-118.70Ma, base in Aptian 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: Kamptneriaceae
References:
Black, M. (1973). British Lower Cretaceous Coccoliths. I-Gault Clay (Part 2). Palaeontographical Society Monograph. 127: 49-112. gs
Bukry, D. (1969). Upper Cretaceous coccoliths from Texas and Europe. University of Kansas Paleontological Contributions, Articles. 51 (Protista 2): 1-79. gsO
Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 132-199. gsO
Gartner, S. (1968). Coccoliths and related calcareous nannofossils from Upper Cretaceous deposits of Texas and Arkansas. University of Kansas Paleontological Contributions, Articles. 48 (Protista 1): 1-56. gsO
Noël, D. (1969). Arkhangelskiella (coccolithes Crétacés) et formes affines du Bassin de Paris. Revue de Micropaléontologie. 11: 191-204. gs
Stover, L. E. (1966). Cretaceous coccoliths and associated nannofossils from France and the Netherlands. Micropaleontology. 12(2): 133-167. gs
Gartnerago compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 8-9-2024
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