Distinguishing features:
Parent taxon (Triscutum): Three-shielded placoliths with a wide central-area spanned by a proximal net or grill.
This taxon: Large (7-10 µm) Triscutum with relatively low and narrow shields, vacant central area
Taxonomy:
Farinacci & Howe catalog pages: T. sullivanii *
Distinguishing features:
Parent taxon (Triscutum): Three-shielded placoliths with a wide central-area spanned by a proximal net or grill.
This taxon: Large (7-10 µm) Triscutum with relatively low and narrow shields, vacant central area
A very thin, granular, plate fills the central area, but is rarely preserved intact. [de Kwnel & Dergen 1993]
Morphology:
LITHS: placolith, elliptical, CA: plate, vacant, ca_disjunct, CROSS-POLARS: R-prominent, rim-bicyclic, |
Lith size: 7->10µm; Data source notes: original description & Bown 1987 |
Geological Range:
Last occurrence (top): in lower part of NJT10 zone (20% up, 169.9Ma, in Bajocian stage). Data source: Mattioli & Erba 1999, fig. 12 - secondary marker
First occurrence (base): near top of NJT7a subzone (90% up, 181.1Ma, in Toarcian stage). Data source: Mattioli & Erba 1999, fig. 12 - secondary marker
Plot of occurrence data:
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 O Bown, P. R. (1987a). Taxonomy, evolution, and biostratigraphy of Late Triassic-Early Jurassic calcareous nannofossils. Special Papers in Palaeontology. 38: 1-118. gs de Kaenel, E. & Bergen, J. A. (1993). New Early and Middle Jurassic coccolith taxa and biostratigraphy from the eastern proto-Atlantic (Morocco, Portugal and DSDP Site 547B). Eclogae Geologicae Helvetiae. 86(861-907): -. gs 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 References:
Triscutum sullivanii compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 10-12-2024
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=11257 Go to Archive.is to create a permanent copy of this page - citation notes |
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