Distinguishing features: Parent taxon (Orthorhabdus): Elongate nannoliths formed of three blades, with c-axis perpendicular to length. Usually curved and asymmetric. Shows low to moderate birefringence. This taxon: Elongate Orthorhabdus species - triangular in plan view, hockey-stick shaped in side view.
The median blade is wider than the two lateral blades and the c-axis lies in the plane of this blade, so this nannolith can be seen in two different orientations
Side view - c-axis horizontal, hockey-stick shape; this is the usual view, the nannolith shows high birefringence, but inverse optical orientation (blue with gypsum plate when orientated SW-NE).
Plan view - c-axis vertical, triangular shape; the nannolith shows low birefringence. Typical forms are symmetrical in plan view, but specimens with a spine developed from the median blade occur in upper part of range.
Geological Range: Last occurrence (top): within NN6 zone (11.90-13.53Ma, top in Serravallian stage). Data source: Young 1998 First occurrence (base): within NN2 zone (19.00-22.82Ma, base in Aquitanian stage). Data source: Young 1998
Plot of occurrence data:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
Bown, P. R. & Dunkley Jones, T. (2012). Calcareous nannofossils from the Paleogene equatorial Pacific (IODP Expedition 320 Sites U1331-1334). Journal of Nannoplankton Research. 32(2): 3-51. gsVO
Bramlette, M. N. & Wilcoxon, J. A. (1967b). Middle Tertiary calcareous nannoplankton of the Cipero section, Trinidad, W.I. Tulane Studies in Geology and Paleontology. 5: 93-131. gsVO
de Kaenel, E. & Villa, G. (1996). Oligocene-Miocene calcareous nannofossil biostratigraphy and paleoeecology from the Iberian Abyssal Plain. Proceedings of the Ocean Drilling Program, Scientific Results. 149: 79-145. gsVO
Gartner, S. (1967a). Calcareous nannofossils from Neogene of Trinidad, Jamaica, and Gulf of Mexico. University of Kansas Paleontological Contributions, Papers. 29: 1-7. gsVO
Müller, C. (1974b). Calcareous nannoplankton, Leg 25 (Western Indian Ocean). Initial Reports of the Deep Sea Drilling Project. 25: 579-633. gsVO
Theodoridis, S. (1984). Calcareous nannofossil biostratigraphy of the Miocene and revision of the helicoliths and discoasters. Utrecht Micropaleontological Bulletin. 32: 1-271. gsVO
Young, J. R. (1998). Neogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 225-265. gsVO
Orthorhabdus serratus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 20-9-2021