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Species Paragloborotalia nana Bolli 1957 | ||||||
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Diagnosis / Definition: | ||||||
Pearson et al. (2006): DESCRIPTION. Type of wall: Normal perforate, coarsely cancellate, sacculifer-type, spinose in life, heavy gametogenetic calcification is often present. Test morphology: Test very low trochospiral, globular, quadrate in outline, chambers globular, much inflated, embracing; in spiral view 4, occasionally 41/2 globular, embracing chambers in ultimate whorl, increasing slowly in size, sutures slightly depressed, straight, last 4 chambers make up about three-quarters of the test size, ultimate chamber may be slightly reduced in size; in umbilical view 4, occasionally 41/2 globular, embracing chambers, increasing slowly in size, sutures slightly depressed, straight, forming a cross, umbilicus very small sized, deep opening, sometimes closed off by surrounding chambers, aperture umbilical-extraumbilical, bordered by a narrow, often thickened, continuous, lip, ultimate chamber may be slightly reduced in size; in edge view chambers globular, spiral side flat, periphery rounded, aperture a low arch extending midway onto the peripheral edge, bordered by a thickened lip. Size: Maximum diameter of holotype 0.25 mm, minimum diameter 0.23 mm, maximum width 0.28 mm. |
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Discussion / Comments: | ||||||
Chaisson & Leckie (1993): Remarks: This species is a member of the spinose "opima" group, which is assigned to the genus Paragloborotalia (Spezzaferri, 1991). Bolli and Saunders (1985, p. 206) describe a gradual evolution of "Globorotalia continuosa" from "G. opima nana." Similar species: P. nana differs from P. continuosa in having a lower arched aperture and more embracing chambers. Pearson et al. (2006): DTSTTNGUISHING FEATURES.- Paragloborotalia nana is a small species, as the name suggests, and tends to be very conservative in morphology. A prominent lip is always present, which often nearly obscures the primary aperture- Paragloborotalia nana usually has 4 chambers in the final whorl. The slowly enlarging chambers in the final whorl give the test a compact, quadrangular appearance. The tight coiling, much inflated, embracing chambers, and very narrow umbilicus combined with straight radial sutures means that the sutures make out a cross pattern in both spiral and umbilical views in four-chambered specimens. P. nana is distinguished from P griffinoides in having a quadrate-shaped, more compact test. In P. nana, the chambers in the ultimate whorl increase more slowly in size with the ultimate chamber nearly equal in size to the penultimate chamber, thus developing a quadrate shape. PHYLOGENETIC RELATIONSHIPS.- P. nana evolved from P. griffinoides in the middle Eocene by developing more inflated, embracing chambers, and a slower rate of chamber size increase in the ultimate whorl. It was ancestral to P. opima in the Oligocene. GEOGRAPHIC DISTRIBUTION .- Worldwide in the low and mid-latitudes. STABLE ISOTOPE PALEOBIOL0GY.-Douglas and Savin (1978) and Poore and Matthews (1 984) recorded distinctly positive ò18O for th;s species indicating a deep planktonic habitat. |
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Systematics: | ||||||
35 Ordo Foraminiferida Superfamilia Globigerinaceae Familia Globigerinidae Genus Paragloborotalia Species Paragloborotalia nana |
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Synonym list: | ||||||
Chaisson & Leckie (1993): 1957 Globorotalia opima nana Bolli. - Bolli : p.118 pl. 28; fig. 3a-c
1983 "Globorotalia" nana Bolli. - Kennett & Srinivasan : p.106 pl. 24; fig. 3-5
1993 Paragloborotalia nana Bolli. - Chaisson & Leckie : p.176 pl. 8; fig. 10-11
Pearson et al. (2006): 1957 Globorotalia opima nana Bolli. - Bolli : p.118 pl. 28; fig. 3a-c [Oligocene Globorotalia opima opima Zone, Cipero Fm.,
Trinidad]
1969 Globorotalia (Turborotalia) opima nana Bolli. - Blow : p.154 pl. 39; fig. 1 [lower Oligocene Zone P20, Cipero Fm., Trinidad]
1977 Globorotalia nana Bolli. - Krasheninnikov & Pflaumann : p.606 pl. 6; fig. 10-11c [Oligocene, DSDP Hole 369A, eastern North Atlantic Ocean]
1978 Globorotalia opima nana Bolli. - Toumarkine : p.714 pl. 8; fig. 3-4 [Oligocene Globorotalia opima opima Zone, DSDP Site
360, southeast Atlantic Ocean]
1985 Globorotalia opima nana Bolli. - Bolli & Saunders : p.202 fig. 26: 16a-c (holotype reillustrated);
fig. 26: 15, 17-20 (paratypes) [Oligocene Globorotalia opima opima Zone, Cipero Fm.,
Trinidad]
1995 Jenkinsella opima nana Bolli. - Poag & Commeau : p.149 pl. 6; fig. 21, 22 [Oligocene, Hammond Well, Maryland]
2004 Paragloborotalia nana Bolli. - Pearson et al. : p.36 pl. 1; fig. 21 [middle Eocene Zone P1 1, Tanzania]
2006 Paragloborotalia nana Bolli. - Pearson et al. : p.86 pl. 5.8; fig. 1-16 (Pl. 5.8, Figs. 1-3: new SEMs of holotype of
Globorotalia opima nana Bolli)
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Specimen: | ||||||
Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM P5661 |
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References: | ||||||
Bolli,H.M. (1957): Blow,W.H. (1969): Krasheninnikov,V.A. and Pflaumann,U. (1977): Toumarkine,M. (1978): Kennett,J. and Srinivasan,M.S. (1983): Bolli,H.M. and Saunders,J.B. (1985): Chaisson,W.P. and Leckie,R.M. (1993): Poag,C.W.. and Commeau,J.A.. (1995): Pearson,P.N.; Nicholas,C.J..; Singano,J.M..; Bown,P.R..; Coxali,H.K..; van Dongen,B.E..; Huber,B.T.; Karega,A..; Lees,J.A..; Misaky,E..; Pancost,R.D..; Pearson,M.. and Roberts,A.P.. (2004): Pearson,P.N.; Olsson,R.K.; Hemleben,C.; Huber,B.T. and Berggren,W.A. (2006): |
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Anonymous: Unedited TaxonConcept data | ||||||
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