Nannotax3 - ntax_cenozoic - Discoaster bergenii

Citation: Discoaster bergenii Knuttel, Russell&Firth, 1989

Synonyms:

D. pentaperforatus Singh & Jafar 1995 - overgrown form [my interpretation - JRY 2020]

Taxonomic discussion: In the taxonomy of de Kaenel et al. (2017) D. bergenii is spearatd from the other speciesi listed here as variants by having stem ridges which extend beyond the central area.

Distinguishing features:
Parent taxon (D. quinqueramus group): Symmetric typically 5-rayed, late Miocene discoasters; rays curved proximally, without bifurcations; well-developed distal star and usually proximal boss
This taxon: very short free rays

Like D. quinqueramus but central-area very wide (>2x free ray length).

Geological Range:
Notes: D. bergenii, D. bergrennii and D. quinqueramus apparently form an anagenetic lineage, with central area size deceasing and free ray length increasing. Distinguishing them is useful for determining position within the early part of zone NN11.
Last occurrence (top): in mid part of NN11 zone (50% up, 6.9Ma, in Messinian stage). Data source: Blair et al 2017
First occurrence (base): at base of NN11 zone (0% up, 8.3Ma, in Tortonian stage). Data source: Blair et al 2017

References:

Bergen, J. A. (1984). Calcareous nannoplankton from Deep Sea Drilling Project Leg 78A: evidence for imbricate underthrusting at the Lesser Antillian active margin. Initial Reports of the Deep Sea Drilling Project. 78A: 411-445. gs

Blair, S. A., Bergen, J. A., de Kaenel, E., Browning, E. & Boesiger, T. M. (2017). Upper Miocene-Lower Pliocene taxonomy and stratigraphy in the circum North Atlantic Basin: radiation and extinction of Amauroliths, Ceratoliths and the D. quinqueramus lineage. Journal of Nannoplankton Research. 37(2-3): 113-144. gs O

Knuttel, S., Russell, M. D. & Firth, J. V. (1989). Neogene calcareous nannofossils from Leg 105: Implications for Pleistocene paleoceanographic trends. Proceedings of the Ocean Drilling Program, Scientific Results. 105: 245-262. gs

Singh, O. P & Jafar, S. A. (1995). Late Miocene discoasters from Sawai Bay Formation, Neill Island, Andaman Sea, India. The Palaeobotanist. 44: 189-206. gs

Theodoridis, S. (1984). Calcareous nannofossil biostratigraphy of the Miocene and revision of the helicoliths and discoasters. Utrecht Micropaleontological Bulletin. 32: 1-271. gs O

Wei, W. (2003). Upper Miocene nannofossil bistratigraphy and taxonomy of Exxon core CH30-43-2 from the Gulf of Mexico. Journal of Nannoplankton Research. 25(1): 17-23. gs

Young, J. R. (1998). Neogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 225-265. gs

Sub-taxa & variants (time control age-window is: 0-800Ma)
				Discoaster compactus stem-ridges extend to edge of central area - very short rays
				Discoaster vinsonii stem-ridges extend to edge of central area - very short rays
				Discoaster abrachiatus no free rays

Discoaster bergenii

References:

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