Catalog entries: Spirocyrtis gyroscalaris
Original description: Similar in form to S. scalaris, but the outline of the segments is rounded rather than angular; it is generally narrower than S. scalaris, becoming broader in younger sediments as it evolves into S. scalaris. Duck-billed vertical tube and three-bladed apical horn both well developed. Seven to nine segments of variable length with two to five rows of subcircular to rectangular pores per segment. Termination ragged.
(based on 70 specimens). Total length 130-180µm; maximum breadth 75-105µm. Phylogeny (rw): Ancestor of S. scalaris and descendant of S. subtilis.
Geological Range:
Last occurrence (top): within Neogene Period (2.59-23.03Ma, top in Piacenzian stage). Data source: Lazarus et al. 2015 - "N age group"
First occurrence (base): within Neogene Period (2.59-23.03Ma, base in Aquitanian stage). Data source: Lazarus et al. 2015 - "N age group"
Plot of occurrence data:
Alexandrovich, J. M. (1989). Radiolarian biostratigraphy of ODP Leg 111, Site 677, eastern equatorial Pacific, late Miocene through Pleistocene. Proceedings of the Ocean Drilling Program, Scientific Results. 111: 245-262. gs V O Nigrini, C. A. (1977). Tropical Cenozoic Artostrobiidae (Radiolaria). Micropaleontology. 23(3): 241-269. gsReferences:
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Spirocyrtis gyroscalaris compiled by the radiolaria@mikrotax project team viewed: 22-3-2023
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