Nannotax3 - ntax_mesozoic - Rhagodiscus pseudoangustus

Distinguishing features:
Parent taxon (Rhagodiscus): Loxolith coccoliths with low rim and central-area filled by a granular plate which may be perforate and/or spine-bearing. In xpl the rim is unicyclic moderately bright, the central area is granular, lacking a clear extinction cross.
This taxon: Small-medium, sub-rectangular with parallel sides, rounded ends and a narrow central area spanned by a large hollow spine base. The rim may be irregularly thickened. Often seen in side view.

Citation: Rhagodiscus pseudoangustus Crux, 1987

Synonyms:

?Zeugrhabdotus pseudoangustus Bralower et al. 1987. Bizarrely the same species was independently described with the same name by two sets of authors at the same time, the descrition of Crux (1987) was, however, published one month earlier than that of Bralower et al. (1987) and so has priority - see de Kaenel & Bergen (1996) Parhabdolithus pseudoangustus;

Geological Range:
Notes: This is an Early Cretaceous species which does not overlap in range with R. angustus
Last occurrence (top): at top of BC13 zone (100% up, 125.3Ma, in Barremian stage). Data source: Bown et al. 1998 - zonal marker
First occurrence (base): within Hauterivian Stage (126.50-132.60Ma, base in Hauterivian stage). Data source: Bown et al. 1998

References:

Aguado, R. et al. (2018). A new record of the Weissert episode from the Valanginian succession of Cehegín (Subbetic, SE Spain): bio- and carbon isotope stratigraphy. Cretaceous Research. 92: 122-137. gs

Applegate, J. L. & Bergen, J. A. (1988). Cretaceous calcareous nannofossil biostratigraphy of sediments recovered from the Galicia Margin, ODP Leg 103. Proceedings of the Ocean Drilling Program, Scientific Results. 103: 293-348. gs O

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

Covington, J. M. & Wise, S. W. (1987). Calcareous nannofossil biostratigraphy of a Lower Cretaceous deep-sea fan complex: Deep Sea Drilling Project Leg 93 Site 603, lower continental rise off Cape Hatteras. Initial Reports of the Deep Sea Drilling Project. 93: 617-660. gs O

Crux, J. A. (1987c). Six new species of calcareous nannofossils from the Lower Cretaceous strata of England and Germany. INA Newsletter. 9(1): 30-35. 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

de Kaenel, E. & Bergen, J. A. (1996b). Mesozoic calcareous nannofossil biostratigraphy from sites 897, 899, and 901, Iberia Abyssal Plain: New biostratigraphic evidence. Proceedings of the Ocean Drilling Program, Scientific Results. 149: 27-59. gs O

Rhagodiscus pseudoangustus

References:

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