Taxonomy and magnetobiochronology of <i>Tribrachiatus</i> and <i>Rhomboaster</i>, two genera of Calcareous nannofossils

Wei, Wüchang; (钟石兰), Zhong Shilan

doi:10.1017/s0022336000023064

Cited by 17 publications

(17 citation statements)

References 30 publications

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“…1988,1989,1990). The taxonomy of most taxa are generally well established, except for the much debated genera Rhomboaster and Tribrachiatus (Perch-Nielsen, 1985;Bybell and Self-Trail, 1997;Aubry et al, 2000;Wei and Zhong, 1996;von Salis et al, 2000;Raffi et al, 2005). Although some investigators have grouped the two under the genus Rhomboaster and recombined all species within Tribrachiatus into Rhomboaster, we prefer to distinguish both genera, only recognizing the following Rhomboaster taxa: Rhomboaster cuspis and the Rhomboaster calcitrapa group, which includes the species Rhomboaster intermedia, Rhomboaster bitrifida and Tribrachiatus spineus.…”

Section: Methodsmentioning

confidence: 99%

The response of calcareous nannofossil assemblages to the Paleocene Eocene Thermal Maximum at the Walvis Ridge in the South Atlantic

Raffi

Backman

Zachos

et al. 2009

Marine Micropaleontology

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Compositions and abundances of calcareous nannofossil taxa have been determined in a ca 170 kyrs long time interval across the Paleocene/Eocene boundary at 1-cm to 10-cm resolution from two ODP Sites (1262, 1263) drilled along the flank of the Walvis Ridge in the South Atlantic. The results are compared to published data from ODP Site 690 in the Weddell Sea. The assemblages underwent rapid evolution over a 74 kyrs period, indicating stressed, unstable and/or extreme photic zone environments during the PETM hyperthermal. This rapid evolution, which created 5 distinct stratigraphic horizons, is consistent with the restricted brief occurrences of malformed and/or weakly calcified morphotypes. The production of these aberrant morphotypes is possibly caused by major global scale changes in carbon cycling in the oceanatmosphere system, affecting also photic zone environments. No marked paleoecologically induced changes are observed in abundances of the genera Discoaster, Fasciculithus and Sphenolithus at the Walvis Ridge sites. Surprisingly, there is no significant correlation in abundance between these three genera, presumed to have had a similar paleoecological preference for warm and oligotrophic conditions.

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Section: Methodsmentioning

confidence: 99%

The response of calcareous nannofossil assemblages to the Paleocene Eocene Thermal Maximum at the Walvis Ridge in the South Atlantic

Raffi

Backman

Zachos

et al. 2009

Marine Micropaleontology

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“…The conventional interpretation of coccolithophore systematics is that there are about 120 well-described heterococcolithophore species (Jordan and Green 1994), with, in almost all cases, interoceanic distributions within broad ecological boundaries (Jordan and Kleijne 1994;Young and Bown 1994;Jordan and Chamberlain 1997). A perception of very widely distributed, rather homogeneous species is well supported by geological evidence of synchronous, apparently sympatric evolution across the world oceans and for near synchronous (on scales of less than a few thousand years) extinction events (Chepstow-Lusty et al 1992;Wei 1993;Wei and Shilan 1996). Research over the past decade via the integration of data from various sources (morphology, life-cycles, and molecular studies) has greatly refined our knowledge of fine scale diversity in this group.…”

Section: Introductionmentioning

confidence: 94%

Species level variation in coccolithophores

et al. 2004

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Coccolithophores are an ideal test group for investigating fine-scale differentiation within the phytoplankton since their taxonomy is rather well-documented and their biomineralised periplasts -the coccoliths -provide a rich suite of qualitative and quantitative morphological characters and a uniquely extensive fossil record. In addition, extant coccolithophore species can be grown in culture and hence are available for studies of morphological variability under controlled conditions, molecular genetic studies and cytological research.For the CODENET project the following extant species with seemingly global occurrence and spanning the biodiversity of coccolithophores were selected: Coccolithus pelagicus, Calcidiscus leptoporus, Umbilicosphaera sibogae, Syracosphaera pulchra, Gephyrocapsa oceanica, and Helicosphaera carteri. These were used as case studies to elucidate their species level biodiversity. The key merit of our approach was the use of multiple, independent lines of evidence, so as to remove the ambiguity implicit in any one type of study. In each case morphotypes of previously uncertain significance have been shown to represent discrete genotypes and probably well-separated species, with divergence times ranging 314 Geisen et al. from about 100 kyrs to >10 myrs. The evolutionary significance of these results is discussed.

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“…Several studies confirmed the validity of this subdivision (e.g., Bybell and Self-Trail, 1997;Dupuis et al, 2003;Tantawy, 2006;Abu Shama et al, 2007;Faris and Salem, 2007;Al Wosabi, 2015). The subdivision of Aubry (1996) ensures the completeness of Zone NP10, but the systematic position and the range of T. digitalis were criticized (e.g., Wei and Zhong, 1996;Raffi et al, 2005).…”

Section: R F C C R R F a A F C R R F C R F R F M A 49 R F C Cmentioning

confidence: 95%

“…The evolution within the Tribrachiatus lineage is characterized by subsequent flattening and rotation, as well as the merging of the two "triplets" (e.g., Wei and Zhong, 1996). Aubry (1996) differentiated between T. digitalis marked by well-merged "triplets", T. contortus marked by well-differentiated "triplets", and T. orthostylus characterized by indistinct "triplets".…”

Section: Tribrachiatus Contortus Zone (Np10)mentioning

confidence: 99%

“…Aubry (1996) differentiated between T. digitalis marked by well-merged "triplets", T. contortus marked by well-differentiated "triplets", and T. orthostylus characterized by indistinct "triplets". On the other hand, Wei and Zhong (1996) considered T. digitalis as a variant of T. contortus. In the original description and later studies, T. digitalis first occurs below the LO of T. contortus (e.g., Aubry, 1996;Dupuis et al, 2003;Tantawy, 2006).…”

Section: Tribrachiatus Contortus Zone (Np10)mentioning

confidence: 99%

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Upper Paleocene-lower Eocene calcareous nannofossil stratigraphy at the Misheiti Section, Central Sinai, Egypt

Kasem¹,

Wise²,

Faris³

et al. 2020

Turkish J Earth Sci

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Dababiya Quarry Beds (DQBs; Dupuis et al., 2003) that were documented in several sections in Egypt (Tantawy, 2006; Khozyem et al., 2013). 2. Studied section and methods Twenty-two bulk rock samples were investigated from the upper Paleocene-lower Eocene at the Misheiti Section, Central Sinai, Egypt (Figure 1). Smear slides were prepared according to Bown and Young (1998) and investigated using a Zeiss Axio-Photo microscope at Florida State University, USA. We counted 300-400 calcareous nannofossil specimens on the slide to recognize the relative abundances of species (Jiang and Gartner, 1986). The calcareous nannofossil diversity represents the total number of species recorded in the sample. Thoracosphaera fragments greater than 4 µm were counted as a whole specimen (Gardin and Monechi, 1998). The state of preservation of the assemblage was described as good (G) for little or no evidence of etching and/or overgrowth, and moderate (M) when specimens exhibited some overgrowth and/or dissolution but the species was still recognizable (Kasem et al., 2017a). The calcium carbonate

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Taxonomy and magnetobiochronology of Tribrachiatus and Rhomboaster, two genera of Calcareous nannofossils

Cited by 17 publications

References 30 publications

The response of calcareous nannofossil assemblages to the Paleocene Eocene Thermal Maximum at the Walvis Ridge in the South Atlantic

The response of calcareous nannofossil assemblages to the Paleocene Eocene Thermal Maximum at the Walvis Ridge in the South Atlantic

Species level variation in coccolithophores

Upper Paleocene-lower Eocene calcareous nannofossil stratigraphy at the Misheiti Section, Central Sinai, Egypt

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