Gartnerago stenostaurion
Classification: Mesozoic -> Arkhangelskiales -> Kamptneriaceae -> Gartnerago -> Gartnerago stenostaurion
Sister taxa: G. obliquum, G. segmentatum, G. costatum, G. diversum, G. stenostaurion, G. clarusora, G. chiasta, G. margaritatus, G. praeobliquum, G. coxalliae, G. nanum, G. ponticula, G. theta, G. sp.,
Distinguishing features: 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.
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Taxonomy:
Citation: Gartnerago stenostaurion (Hill, 1976) Perch-Nielsen, 1984Rank: SpeciesBasionym: Broinsonia stenostaurion Hill, 1976Synonyms: Arkhangelskiella antecessor Burnett, 1998
Crucribrum striatum ssp. striatum (Stradner 1963) Wise 1983 [Wise 1983 included B. stenostaurion in their synonymy]Notes & discussion: The narrow, bright rim cycle is a unique feature of Gartnerago, and the dark central area plate is similar to those seen in Gartnerago segmentatum and Gartnerago obliquum. Small specimens of G. stenostaurion most closely resemble Crucicribrum anglicum Black, 1973, a close ally of Gartnerago with a distinctly perforate central area plate. The relationships between these early Gartnerago taxa is not fully understood.
Wise (1983) used the name Crucribrum striatum ssp. striatum for this taxon - based on reinterpretation of the holotype of Cretarhabdus striatum (Stradner 1963), but the holtype has since been re-imaged (Stradner et al. 2010) and shown to be a cretarhabdid.
The species is divided into small (<6µm) and large (>6µm) varieties by Bown in Kennedy et al. (2000).
Farinacci & Howe catalog pages: Broinsonia stenostaurion * , Arkhangelskiella antecessor *
Distinguishing features: 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.
Morphology remarks: The narrow, bright rim cycle is a unique feature of Gartnerago, and the dark central area plate is almost identical to those seen in Gartnerago segmentatum and Gartnerago obliquum. Small specimens of G. stenostaurion most closely resemble Crucicribrum anglicum Black, 1973, a close ally of Gartnerago with a distinctly perforate central area plate. The relationships between these early Gartnerago taxa is not fully understood.
Geological Range:
Last occurrence (top): within NC10a subzone (100.45-103.13Ma, top in Cenomanian stage). Data source: Gale et al., 2011
First occurrence (base): within Late Aptian Substage (112.95-122.98Ma, base in Aptian stage). Data source: Kennedy et al., 2000
Plot of occurrence data:
Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notesNote to users in China - the diagram may not plot unless you use a VPN since I use google services on the website. If this is a problem please contact me 谢谢.Taxon plotted: Gartnerago stenostaurion, synonyms included - Broinsonia stenostaurion; Gartnerago stenostaurion; space-time plot ::
Samples map :: Parent: Gartnerago
References:
Bown, P. R. (2005c). Early to Mid-Cretaceous Calcareous Nannoplankton from the Northwest Pacific Ocean, Leg 198, Shatsky Rise. Proceedings of the Ocean Drilling Program. Scientific Results. 198: 1-82. gs
Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 132-199. gs
Gale, A. S. et al. (2011). The uppermost Middle and Upper Albian succession at the Col de Palluel, Hautes-Alpes, France: An integrated study (ammonites, inoceramid bivalves, planktonic foraminifera, nannofossils, geochemistry, stable oxygen and carbon isotopes, cyclostratigraphy). Cretaceous Research. 32: 59-130. gs
Hill, M. E. (1976). Lower Cretaceous calcareous nannofossils from Texas and Oklahoma. Palaeontographica Abteilung B. 156: 103-179. gs
Kennedy, W. J. et al. (2000). Integrated stratigraphy across the Aptian-Albian boundary in the Marnes Bleues, at the Col de Pre _-Guittard, Arnayon (Drome), and at Tartonne (Alpes-de-Haute-Provence), France: a candidate Global Boundary Stratotype Section and Boundary Point for the base of the Albian Stage. Cretaceous Research. 21: 591-720. gs
Perch-Nielsen, K. (1984). Validation of new combinations. INA Newsletter. 6(1): 42-46. gs
Stradner, H., Aubry, M. -P. & Bonnemaison, M. (2010). Calcareous nannofossil type specimens in the collection of the Geological Survey of Austria: A taxonomic and stratigraphic update. Jahrbuch der Geologischen Bundesanstalt. 150(1-2): 9-84. gs
Wise, S. W. (1983). Mesozoic and Cenozoic calcareous nannofossils recovered by DSDP Leg 71 in the Falkland Plateau region, Southwest Atlantic Ocean. Initial Reports of the Deep Sea Drilling Project. 71: 481-550. gs
