Distinguishing features: Medium to large, broadly elliptical Watznaueria with narrow central area almost filled with axial cross bars.
Taxonomy:
Farinacci & Howe catalog pages: L. contractus * , W. colacicchii *
Distinguishing features: Medium to large, broadly elliptical Watznaueria with narrow central area almost filled with axial cross bars.
Morphology: This is a mid-Jurassic species associatied with the evolion of Watznaueria from Lotharingius and is well-separated in time from the later species with an axial cross.
Phylogenetic relations: Apparently a transitional form between Watznaueria and Lotharingius (Bown & Cooper 1988, p.39)
Tags | LITHS: placolith, elliptical, CA: cross-axial, ca_disjunct, CSPH: equant, monomorphic, CROSS-POLARS: rim-unicyclic, R-prominent, |
Metrics | Lith size: 5->9µm; Data source notes: original description & illustrated specimens |
Geological Range:
Last occurrence (top): within NJ12a subzone (165.55-166.40Ma, top in Callovian stage). Data source: Bown & Cooper 1998
First occurrence (base): at base of NJ8b subzone (0% up, 171.8Ma, in Aalenian stage). Data source: Bown & Cooper 1998 (fig 4) - zonal event;Mattioli & Erba 1999, fig. 12 (slightly later)
Plot of occurrence data:
Bown, P. R. & Cooper, M. K. E. (1989b). New calcareous nannofssils from the Jurassic. Journal of Micropalaeontology. 8: 91-96. gs V O Bown, P. R. & Cooper, M. K. E. (1998). Jurassic. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 34-85. gs Bown, P. R., Cooper, M. K. E. & Lord, A. R. (1988). A calcareous nannofossil biozonation scheme for the early to mid Mesozoic. Newsletters on Stratigraphy. 20: 91-114. gs Cobianchi, M., Erba, E. & Pirini-Radrizzani, C. (1992). Evolutionary trends of calcareous nannofossil genera Lotharingius and Watznaueria during the Early and Middle Jurassic. Memorie di Scienze Geologiche. 43: 19-25. gs V O Mattioli, E. & Erba, E. (1999). Synthesis of calcareous nannofossil events in Tethyan lower and middle Jurassic successions. Rivista Italiana di Paleontologia e Stratigrafia. 105(3): 343-376. gs V O Mattioli, E. (1996). New calcareous nannofossil species from the Early Jurassic of Tethys. Rivista Italiana di Paleontologia e Stratigrafia. 102(3): 397-412. gs V OReferences:
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Watznaueria contracta compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 28-1-2021
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