Nannotax3 - ntax_main - Diloma primitiva

Citation: Diloma primitiva (Worsley, 1971) Wind & Cepek, 1979

Basionym: Arkhangelskiella primitiva Worsley, 1971

Distinguishing features:
Parent taxon (Diloma): Elliptical loxoliths with a rim that appears tricyclic, composed of inner and outer rim cycles and a proximal plate. The outer rim cycle and proximal plate are only weakly birefringent, while the blocky inner rim cycle is brightly birefringent. Central structures are variable but include cross bars, lateral bars and curving concentric bars.
This taxon: Medium-sized elliptical form with a relatively delicate rim that in LM appears to consist of three narrow cycles: the inner and outer cycles are weakly birefringent (grey) while the middle cycle is brightly birefringent (white). The complex central structure comprises axial cross bars, concentric bars and numerous lath-like radial bars.

Geological Range:
Last occurrence (top): within Early Aptian Substage (118.70-121.40Ma, top in Aptian stage). Data source: Bown et al. 1998
First occurrence (base): within Valanginian Stage (132.60-137.70Ma, base in Valanginian stage). Data source: Bown et al. 1998

References:

Applegate, J. L. & Bergen, J. A. (1988). Cretaceous calcareous nannofossil biostratigraphy of sediments recovered from the Galicia Margin, ODP Leg 103. Proceedings of the Ocean Drilling Program, Scientific Results. 103: 293-348. gs O

Bown, P. R. (2005c). Early to Mid-Cretaceous Calcareous Nannoplankton from the Northwest Pacific Ocean, Leg 198, Shatsky Rise. Proceedings of the Ocean Drilling Program, Scientific Results. 198: 1-82. gs O

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. gs O

Wind, F. H. & Cepek, P. (1979). Lower Cretaceous calcareous nannoplankton from DSDP Hole 397A (northwest African Margin). Initial Reports of the Deep Sea Drilling Project. 47A: 221-235. gs

Worsley, T. R. (1971). Calcareous nannofossil zonation of Upper Jurassic and Lower Cretaceous sediments from the Western Atlantic. In, Farinacci, A. (ed.) Proceedings of the Second Planktonic Conference Roma 1970. Edizioni Tecnoscienza, Rome 2: 1301-1321. gs O

Diloma primitiva

References:

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