Distinguishing features: Parent taxon (Podorhabdales): Placolith (or modified placolith) coccoliths showing little or no imbrication. Typically, V-units form distal shield, R-units form proximal shield. This taxon: Regular placoliths; central-area, with cross-bars or perforated plate; often with tall, hollow spines. Distal shield elements non-imbricate V-units; proximal shield and inner cycle formed from R-units. Rim often appears beaded in LM
Daughter taxa (time control age-window is: 0-800Ma)
Granddaughter taxa
central area with 2-8 large openings
Podorhabdus Sub-circular, rim broad; central area spanned by a granular bar supporting a broad, tall, hollow, flaring spine.
Hexapodorhabdus Elliptical; central area spanned by six broad bars delineating six large perforations, including one at each end of the central area. Central hollow spine.
Citation: Axopodorhabdaceae Wind & Wise in Wise & Wind, 1977taxonomic rank: FamilyType species: Axopodorhabdus Wind and Wise in Wise and Wind, 1977.Taxonomic discussion: The generic taxonomy of this group is unsatisfactory. Using genera based on number of openings in the central area rather than ultrastructure is liable to be artificial. So far no alternative criterion for grouping has been established, but some of the illogicality could be reduced, in particular it might make sense to combinne Hexapodorhabdus, Octopodorhabdus and Octocyclus into one genus (with 6-8 large openings) and Dodekapodorhabdus, Perissocyclus and Teichorhabdus into another (with mutiple small openings around a well developed process).
Distinguishing features: Parent taxon (Podorhabdales): Placolith (or modified placolith) coccoliths showing little or no imbrication. Typically, V-units form distal shield, R-units form proximal shield. This taxon: Regular placoliths; central-area, with cross-bars or perforated plate; often with tall, hollow spines. Distal shield elements non-imbricate V-units; proximal shield and inner cycle formed from R-units. Rim often appears beaded in LM
Morphology: Placoliths with two shields and a central-area, spanned by axial cross-bars or granular plates with variable numbers of perforations; the central structure generally supports tall, hollow spines. The distal shield is formed from V-unit elements joined along radial or near-radial sutures that show little or no imbrication. The proximal shield and inner cycle (if present) are formed from R-units. LM image is generally dark, but bright inner-cycles may be visible. The image is characterised by clearly visible shield elements, often giving a 'beaded' appearance around the inner edge of the shields. The informal term podorhabdid is useful and widely used to described the coccoliths classified together in the Axopodorhabdaceae.
Search data:
: placolith,
Lith size: 0->0µm;
The morphological data given here can be used on the advanced search page. See also these notes
Geological Range: Last occurrence (top): at top of Maastrichtian Stage (100% up, 66Ma, in Danian stage). Data source: Total of ranges of the species in this database First occurrence (base): within Late Pliensbachian Substage (182.7-187.56Ma, base in Pliensbachian stage). Data source: Total of ranges of species in this database
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
Neptune data: this is a higher taxon page so Neptune data is not plotted. For the customisable plot option go to a genus page Parent: Podorhabdales
References:
Bown, P. R. & Cooper, M. K. E. (1998). Jurassic. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 34-85. gsO
Bown, P. R. & Young, J. R. (1997). Mesozoic calcareous nannoplankton classification. Journal of Nannoplankton Research. 19(1): 21-36. gs
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. gsO
Grün, W. & Allemann, F. (1975). The Lower Cretaceous of Caravaca (Spain): Berriasian Calcareous Nannoplankton of the Miravetes Section (Subbetic Zone, Prov. of Murcia). Eclogae Geologicae Helvetiae. 68: 147-211. gsO
Wise, S. W. & Wind, F. H. (1977). Mesozoic and Cenozoic calcareous nannofossils recovered by DSDP Leg 36 drilling on the Falkland Plateau, south-west Atlantic sector of the Southern Ocean. Initial Reports of the Deep Sea Drilling Project. 36(269-491): -. gsO
Axopodorhabdaceae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 6-12-2023
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