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Species Globorotalia tosaensis Takayanagi & Saito 1962 | ||||||
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| Discussion / Comments: | ||||||
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Bolli & Saunders (1985): Several sites of DSDP Legs 4 and 15 (29, 30, 31, 148, 154A) drilled in the Caribbean recorded stratigraphic intervals of varying magnitude between the last occurrence of the index forms G. miocenica/G. exilis and the first G. truncatulinoides. Forms occur within this interval that at the time were regarded as being identical or very close to the G. tosaensis as published by Berggren (1968) from a North Atlantic piston core (Chain 61, Station 171). At the time Bolli (1970) regarded these forms as probably related to Berggren's specimens but atypical because of their exceedingly thick walls. To name the interval, Bolli (1970) used this form as a zonal marker and called it Globorotalia truncatulinoides cf. tosaensis. The zone itself was defined as 'interval with zonal marker from the extinction of Globorotalia exilis/Globorotalia miocenica to the first occurrence of Globorotalia truncatulinoides truncatulinoides'. Bolli & Premoli Silva (1973) slightly altered it to 'interval from the extinction of Globorotalia miocenica to first occurrence of Globorotalia truncatulinoides truncatulinoides'. The zone was regarded as representing the topmost Pliocene. Recent work has shown typical G. tosaensis tosaensis to he rare and often absent in the Atlantic province. Re examination of Caribbean specimens of forms originally called G. truncatulinoides cf. tosaensis by Bolli (1970) are better referred to G. truncatulinoides pachytheca. They are, however, somewhat atypical in that compared with the holotype they are exceedingly thick walled, more inflated on the umbilical side and with the peripheral keel often overgrown by pustules making it difficult to recognize The specimen figured by Bolli (1970, pl. 3, figs. 1& 18) is of Pleistocene age and occurs with typical G. truncatulinoides truncatulinoides and G. truncatulinoides excelsa. The Caribbean specimens from DSDP Site 31-3-1, 100-102cm and Site 148-15-6, 88-90, 106-108 and 127-129 mm, have again been compared with paratypes of G. tosaensis tosaensis, and with G. crassaformis ronda specimens received from W. H. Blow from Jamaican material, from where he described the subspecies. The thick walled Caribbean specimens are now regarded as being intermediate between the two taxa. They possess the strongly rounded periphery of ronda but tests are more compact, less lobate and somewhat higher on the umbilical side as in tosaensis. We here propose that the G. truncatulinoides cf. tosaensis Zone by Bolli in 1970 be renamed the G. tosaensis tosaensis Zone. The interval certainly occurs in the Atlantic and Caribbean provinces but, due to the scarcity of the nominate species, usually has to be identified on indirect evidence in those areas (absence of G. miocenica, G. exilis, G. truncatulinoides truncatulinoides). Chaisson & Leckie (1993): Remarks: Based on its rarity in tropical regions and its widely accepted relation to Globorotalia truncatulinoides (Kennett and Srinivasan, 1983), this species is thought to have been primarily a temperate-latitude dweller. G. tosanensis has five to five and a half chambers in its final whorl. These chambers are rounded and perforate through their edges. The umbilical apices are also rounded. The texture of the test is often rough, heavily encrusted with secondary calcite. The thin-shelled utenuitheca" form is too rare at this site to be of stratigraphic value. Similar species: Srinivasan and Kennett (1981b) note that, although a simple gradation is present between G. tosaensis and G. truncatulinoides at DSDP Site 206 (32°S, 165°E in the New Caledonia Basin), further north at DSDP Site 208 (26°S, 161°E on the North Howe Rise) "the relative abundance of the two forms fluctuates significantly within the interval of overlap." Scanning electron microscopy of many specimens from Site 806 reveals a continuous morphological cline between the two species with respect to perforation along the periphery. Imperforation was generally best developed on the oldest chamber in the final whorl. A specimen was designated G. truncatulinoides if this chamber had an imperforate band. Globorotalia crassaformis has only four to four and a half chambers in its final whorl and is distinctly more lobate in equatorial outline than either G. tosaensis or G. truncatulinoides. |
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| Systematics: | ||||||
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1 Superregnum Eukaryota Regnum Protoctista Phylum Ciliophora Subphylum Postciliodesmatophora Ordo Globigerinida Superfamilia Globorotaliaceae Superfamilia Nonionacea Familia Globorotaliidae Genus Globorotalia Species Globorotalia tosaensis |
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| Synonym list: | ||||||
| Bolli & Saunders (1985): 1970 Globorotalia cf. tosaensis Takayanagi & Saito. - Bolli : p.583 pl.3, figs.16-18
1985 Globorotalia cf. tosaensis Takayanagi & Saito. - Bolli & Saunders : p.239
Vincent & Toumarkine (1990): 1962 Globorotalia tosaensis Takayanagi & Saito. - Takayanagi & Saito : p. 81 pl. 28, figs. 11-12
1990 Globorotalia tosaensis Takayanagi & Saito. - Vincent & Toumarkine : p. 803
Chaisson & Leckie (1993): 1962 Globorotalia tosaensis Takayanagi & Saito. - Takayanagi & Saito : p.81 pl. 28; fig. 11a-12c
1972 Globorotalia tosaensis Takayanagi & Saito. - Lamb & Beard : p.56 pl. 22, fig. 1-7;
pl. 23, fig. 1-2
1972 Globorotalia tosaensis Takayanagi & Saito. - Jenkins & Orr : p.1104 pl. 33; fig. 1-3
1975 Globorotalia tosaensis Takayanagi & Saito. - Stainforth et al. : p.413 fig. 206-207
1983 Globorotalia (Truncorotalia) tosaensis Takayangi & Saito. - Kennett & Srinivasan : p.148 pl. 34, fig. 1;
pl. 35, fig. 1-3
1985 Globorotalia tosaensis tosaensis Takayanagi & Saito. - Bolli & Saunders : p.234 fig. 37.8
1993 Globorotalia tosaensis Takayanagi & Saito. - Chaisson & Leckie : p.174 pl. 6; fig. 1-2
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| Was used in synonym list of: | ||||||
| Stratigraphy - absolute ages: | ||||||
| FAD: 3.35 ± 0 [Ma], Berggren et al. (1995) LAD: 0.65 ± 0 [Ma], Berggren et al. (1995) |
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| References: | ||||||
Takayanagi,Y. and Saito,T. (1962): Bolli,H.M. (1970): Jenkins,D.G. and Orr,W.N. (1972): Lamb,J.L. and Beard,J.H. (1972): Stainforth,R.M.; Lamb,J.L.; Luterbacher,H.P.; Beard,J.H. and Jeffords,R.M. (1975): 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.; Hilgen,F.J.; Langereis,C.G.; Kent,D.V.; Obradovich,J.D.; Raffi,I.; Raymo,M.E. and Shackleton,N.J. (1995): |
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| Anonymous: Unedited TaxonConcept data | ||||||
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