Nannotax3 - ntax_mesozoic - Haqius circumradiatus

Distinguishing features:
Parent taxon (Haqius): Unicyclic, elliptical and circular placolith coccoliths with a narrow or closed central area and a characteristically dark gray (low birefringence) XPL image.
This taxon: Large (8-10 µm) circular Haqius species.

Citation: Haqius circumradiatus (Stover, 1966) Roth, 1978

Basionym: Coccolithites circumradiatus Stover, 1966

Synonyms: Cyclagelosphaera circumradiata (Stover, 1966)
Cyclococcolithus circumradiatus (Stover, 1966)
Markalius circumradiatus (Stover, 1966) Perch-Nielsen 1968 Cyclagelosphaera? chronolitha Bukry (1969) [cf. Thierstein 1973 - intersting suggestion but not certain]

Medium to large unicyclic circular placolith with a narrow or closed central area. Under LM XPL the shields appear pale gray crossed by diagonal extinction lines, with a darker central region, and the numerous individual elements are usually visible.

Geological Range:
Last occurrence (top): within UC15d subzone (75.85-76.77Ma, top in Campanian stage). Data source: Burnett 1998
First occurrence (base): in mid part of CC2 zone (50% up, 139.3Ma, in Berriasian stage). Data source: Bown et al. 1998 (fig 5.1)

References:

Bown, P. R. & Concheyro, A. (2004). Lower Cretaceous calcareous nannoplankton from the Neuquen Basin, Argentina. In, Villa, G., Lees, J. A. & Bown, P. R. (eds) Calcareous Nannofossil Palaeoecology and Palaeocenographic Reconstructions, Proceedings of the INA9 conference, Parma 2002. Marine Micropaleontology . 52(1-4): 51-84. gs

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 O

Bown, P. R., Rutledge, D. C., Crux, J. A. & Gallagher, L. T. (1998). Lower Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 86-131. gs O

Bralower, T. J., Monechi, S. & Thierstein, H. R. (1989). Calcareous nannofossil zonation of the Jurassic-Cretaceous boundary interval and correlation with the geomagnetic polarity timescale. Marine Micropaleontology. 14: 153-235. gs

Bukry, D. (1969). Upper Cretaceous coccoliths from Texas and Europe. University of Kansas Paleontological Contributions, Articles. 51 (Protista 2): 1-79. gs O

Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 132-199. gs O

Crux, J. A. (1980). A biostratigraphical study of Upper Cretaceous nannofossils from South-east England and North France. PhD thesis, University College London. -. gs

Crux, J. A. (1989). Biostratigraphy and palaeogeographical applications of Lower Cretaceous nannofossils from north-western Europe. In, Crux, J. A. & van Heck, S. E. (eds) Nannofossils and their applications: Proceedings of the 2nd INA Conference, London 1987. British Micropalaeontological Society Publication Series . 143-211. gs

Püttmann, T. & Mutterlose, J. (2019). Calcareous nannofossils from a Late Cretaceous nearshore setting. Journal of Nannoplankton Research. S4: 81-88. gs

Roth, P. H. (1978). Cretaceous nannoplankton biostratigraphy and oceanography of the northwestern Atlantic Ocean. Initial Reports of the Deep Sea Drilling Project. 44: 731-760. gs

Stover, L. E. (1966). Cretaceous coccoliths and associated nannofossils from France and the Netherlands. Micropaleontology. 12(2): 133-167. gs

Thierstein, H. R. (1973). Lower cretaceous calcareous nannoplankton biostratigraphy. Abhandlungen der Geologischen Bundesanstalt. 29: 3-52. gs

Thomsen, E. (1987). Lower Cretaceous calcareous nannofossil biostratigraphy in the Danish Central Trough. Danmarks Geologiske Undersøgelse. 20: 1-89. gs

Haqius circumradiatus

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