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Species Praeorbulina sicana De Stefani 1950 | ||||||
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Discussion / Comments: | ||||||
Bolli & Saunders (1985): A re study of the holotype of this species has shown that it has 4 apertures around the base of the last chamber (Jenkins et al , 1981 and holotype refigured here as Fig. 24.7). For this reason it is removed to the genus Praeorbulina. Also for this reason and because of the greater envelopment of the test by the last chamber with subsequent complete loss of the umbilicus, the species is not considered to be conspecific with G. bisphericus as has been suggested (Blow, 1969). It is believed to be an intermediate form in the lineage between G. bisphericus and P. glomerosa, curva Chaisson & Leckie (1993): Remarks: Kennett and Srinivasan (1983) acceded to the view of Jenkins et al. (1981) that this species is distinct from Globigerinoides bisphericus and belongs in the genus Praeorbulina. Because it is a zonal marker species, we have applied a narrow species concept. In this study, P. sicana must have at least three low apertures at the base of the final chamber (see Jenkins et al., 1981). Similar species: See Globigerinoides sicana/bisphericus. The final chamber of P. sicana tends to be larger and more embracing than G. sicana/bisphericus, and it has at least three apertures at the base of the base of the final chamber, compared with two in the latter taxon. |
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Systematics: | ||||||
1 Superregnum Eukaryota Regnum Protoctista Phylum Ciliophora Subphylum Postciliodesmatophora Ordo Globigerinida Superfamilia Globigerinaceae Superfamilia Nonionacea Familia Globigerinidae Genus Praeorbulina Species Praeorbulina sicana |
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Synonym list: | ||||||
Chaisson & d'Hondt (2000): 1950 Globigerinoides sicanus De Stefani. - de Stefani : p fig 6
Bolli & Saunders (1985): 1945 Globigerinoides conglobatus Brady. - Cushman & Stainforth : pl.13, fig.6 not G. conglobatus (Brady)
1952 Globigerinoides sicana Stefani. - de Stefani : p.9 not re-illustrated
1985 Praeorbulina sicana De Stefani. - Bolli & Saunders : p.200 figs. 24.7; 7,9,12
Vincent & Toumarkine (1990): 1952 Globigerinoides sicana Stefani. - de Stefani : p.9 (type figure designated as Globigerinoides conglobata of Cushman and Stainforth, 1945, p. 68, pl. 13, fig. 6)
1990 Praeorbulina sicana De Stefani. - Vincent & Toumarkine : p.831 pl. 2, figs, 22-24
Chaisson & Leckie (1993): 1950 Globigerinoides sicanus De Stefani. - de Stefani : p.9 fig. 6
1983 Globigerinoides sicanus De Stefani. - Kennett & Srinivasan : p.62 pl. 13; fig. 4-6
1985 Praeorbulina sicana De Stefani. - Bolli & Saunders : p.199 fig. 24.7
1993 Praeorbulina sicana De Stefani. - Chaisson & Leckie : p.170 pl. 2; fig. 5-6
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Stratigraphy - absolute ages: | ||||||
FAD: 16.4 ± 0 [Ma], Berggren et al. (1995) LAD: 14.8 ± 0 [Ma], Berggren et al. (1995) |
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References: | ||||||
Cushman,J.A. and Stainforth,R.M. (1945): de Stefani,T. (1950): de Stefani,T. (1952): Kennett,J. and Srinivasan,M.S. (1983): Bolli,H.M. and Saunders,J.B. (1985): Vincent,E. and Toumarkine,M. (1990): Chaisson,W.P. and Leckie,R.M. (1993): Berggren,W.A.; Kent,D.V.; Swisher,C.C. and Aubry,M.P. (1995): Chaisson,W.P. and d'Hondt,S.L. (2000): |
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Anonymous: Unedited TaxonConcept data | ||||||
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Taxon relations
Ranking (experimental) |