Cretarhabdus conicus
SEM photo of Cretarhabdus conicus from Mutterlosa, 1992b (Pl. 3, Fig. 2)
Set number: 3023
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Set number: 3022
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Set number: 3021
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Set number: 3019
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Set number: 3020
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Cretarhabdus conicus Bramlette & Martini, 1964
The holotype is preserved in side view, whereas the isotype is in plan view and clearly shows the arm tips of the axial cross overlapping the pelaga.
The entire species exhibits first-order, slightly greyish-white interference colours. The pelaga of Cretarhabdus conicus displays weak inclined extinction and length-fast (-) elongation in its natural settling position, in plan view under crossed polars.
Species of Cretarhabdus are constructed of cretarhabdid pelaga surrounding a large central area spanned by an axial cross whose arm tips overlap the pelaga, supporting a distal process, a characteristic feature of Cretarhabdus conicus. The inter-cross area is occupied by lateral bars that delimit pores arranged in two or more complete concentric cycles. The number of pores in the outer cycle is typically 16 or more.
Bramlette, M. N. & Martini, E. 1964. The great change in calcareous nannoplankton fossils between the Maastrichtian and Danian. Micropaleontology. 10(2): 291-322.
Mutterlose, J., 1992b. Lower Cretaceous nannofossil biostratigraphy off northwestern Australia (Leg 123). Proceedings of the Ocean Drilling Program, Scientific Results 123, 343-368.
Holotype
Cretarhabdus conicus
Bramlette & Martini, 1964
Late Maastrichtian
Arkadelphia Clay, USGS locality 16991, Alabama, USA