Nannotax3 - ntax_main - Calcivascularis jansae

Citation: Calcivascularis jansae Wiegand, 1984

Synonyms:

Mitrolithus irregularis Prins 1969 [invalid]
Mitrolithus jansae (Wiegand, 1984) Bown in Young et al., 1986
Eoconusphaera jansae (Wiegand, 1984) Kristan-Tollmann 1988

Taxonomic discussion: Initially described in it’s own genus Calcivascularis Wiegand, 1984, but transferred to Mitrolithus by Bown in Young et al. (1986) following work of Prins (1969) who suggested it was derived from M. elegans

Distinguishing features:
Parent taxon (Calcivascularis): Protolith coccoliths with high rim, inner rim cycle not clearly developed, upper part of coccolith filled by mass of radiating elements.
This taxon: Very tall, narrow, steeply sloping rim with a central area filled with a mass of radially arranged elements. Most commonly seen in side view.

Has a distinctly tethyan biogeographic range but occassionally seen in boreal sections.

Geological Range:
Last occurrence (top): within NJ6 zone (181.57-183.52Ma, top in Toarcian stage). Data source: Bown & Cooper 1998; Mattioli & Erba 1999
First occurrence (base): in mid part of NJT2b subzone (50% up, 197.1Ma, in Sinemurian stage). Data source: Mattioli & Erba 1999, fig. 12

References:

Bown, P. R. & Cooper, M. K. E. (1989a). Conical nannofossils in the Mesozoic. 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 . 98-106. gs

Bown, P. R. & Cooper, M. K. E. (1998). Jurassic. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 34-85. gs O

Bown, P. R. & Young, J. R. (1997). Mesozoic calcareous nannoplankton classification. Journal of Nannoplankton Research. 19(1): 21-36. gs

Bown, P. R. (1987a). Taxonomy, evolution, and biostratigraphy of Late Triassic-Early Jurassic calcareous nannofossils. Special Papers in Palaeontology. 38: 1-118. gs

Bown, P. R. (1987b). The structural development of Early Mesozoic coccoliths and its evolutionary and taxonomic significance. Abhandlungen der Geologischen Bundesanstalt. 39: 33-49. gs

Kristan-Tollmann, E. (1988). Coccolithen aus den Älteren Allgäuschichten (Alpiner Lias, Sinemur) von Timor, Indonesien. Geologisch-Paläontologische Mitteilungen Innsbruck. 15: 71-83. gs

Mattioli, E. & Erba, E. (1999). Synthesis of calcareous nannofossil events in Tethyan lower and middle Jurassic successions. Rivista Italiana di Paleontologia e Stratigrafia. 105(3): 343-376. gs

Menini, A., Mattioli, E., Spangenberg, J. E., Pittet, B. & Suan, G. (2018). New calcareous nannofossil and carbon isotope data for the Pliensbachian/Toarcian boundary (Early Jurassic) in the western Tethys and their paleoenvironmental implications. Newsletters on Stratigraphy. -. gs

Prins, B. (1969). Evolution and stratigraphy of cocolithinids from the Lower and Middle Lias. In, Bronnimann, P. & Renz, H. H. (eds) Proceedings of the First International Conference on Planktonic Microfossils, Geneva 1967. E. J. Brill, Leiden 547-558. gs

Sandoval, J., et al. (2012). The Toarcian in the Subbetic basin (southern Spain): bio-events (ammonite and calcareous nannofossils) and carbon-isotope stratigraphy. Palaeogeography Palaeoclimatology Palaeoecology. 342-3: 40-63. gs

Wiegand, G. E. (1984). Two new genera of calcareous nannofossils from the Lower Jurassic. Journal of Paleontology. 58(4): 1151-1155. gs

Young, J. R., Teale, C. T. & Bown, P. R. (1986). Revision of the stratigraphy of the Longobucco Group (Liassic, southern Italy); based on new data from nannofossils and ammonites. Eclogae Geologicae Helvetiae. 79(1): 117-135. gs

Calcivascularis jansae

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