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Species Clavigerinella akersi Bolli et al. 1957 | ||||||
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| Diagnosis / Definition: | ||||||
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Pearson et al. (2006): DESCRIPTION.- Type of wall: Smooth, normal perforate or weakly cancellate, possibly spinose. Test morphology: Planispiral or pseudoplanispiral, evolute, biumbilicate or showing a subtly raised spiral side and very shallow umbilicus; 4-4 1/2 rapidly enlarging chambers in the final whorl; final 2-4 chambers radially elongate to digitate, giving the shell a highly lobulate peripheral outline; distal chamber ends of some or all of the chambers terminate in distinctly spherical, bulbous swellings; equatorial high arched aperture, symmetrical or slightly asymmetrical, bordered by a smooth broad, imperforate lip; relict apertural lips commonly form "web-like" extension along sutures; sutures are shallow, straight, becoming curved, short compared to overall chamber height. Size: Maximum diameter of holotype 0.86 mm, greatest thickness 0.23 mm. Paratypes range from 0.49 to 0.73 mm in greatest diameter (Bolli, Loeblich and Tappan, 1957). |
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| Discussion / Comments: | ||||||
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Toumarkine & Luterbacher (1985): The most important feature of the species is the bulbous, clavate shape of the chambers of the last whorl. It has only 4 chambers in the last whorl instead of 4 to 5 as in the subspecies of C. eocanica. Bolli (1957): Clavigerinella akersi Bolli, Loeblich, and Tappan is distinguished from C. jarvisi (Cushman) by having the later, elongate chambers distinctly inflated at the outer ends. It is more restricted in its range and may be regarded as a characteristic index fossil. Petters (1954, p. 40) described Hastigerinella columbiana from the middle Eocene Carreto formation of Colombia. The figures for the species show the chambers to be club shaped though not as distinctly so as in Clavigerinella akersi; the aperture is not visible on the figure, but is described as "a rather wide arched slit with a slight lip at base of last formed chamber, slightly ventrally of periphery." Similar or identical forms possessing an equatorial aperture which occur in the middle Eocene of Trinidad could possibly represent a juvenile stage of Clavigerinella akersi or an intermediate stage between C. jarvisi and C. akersi. (See pl. 35, figs. 3a,b; specimen (USNM P5700) from the Hantkenina aragonensis zone, Navet formation, between mileposts 12% and 12% of the Brasso Tamana Road, Central Range, sample K 8775 (TTOC 177647).) It may also be assumed that Hastigerinella eocanica Nuttall belongs to Clavigerinella, although the aperture is not preserved on the types figured by Nuttall. Pearson et al. (2006): DISTINGUISHING FEATURES.- Clavigerinella akersi is distinguished from other species of Clavigevinella by having bulbous terminal swellings in the final 1-3 chambers. According to Blow (1 979) there is also swelling at the base of the chambers but this also occurs in C. eocanica. It is distinguished from Parasubbotina prebetica by the planispiral coiling, lateral compression of the test, rapidly lengthening chambers and fully equatorial position of the aperture. DISCUSSION.- Complete specimens are rare. It is usually recognized from detached chambers. PHYLOGENETIC RELATIONSHIPS.- This species probably evolved from C. eocanica in the uppermost early Eocene (E7) by inflation of the digitate chambers into a terminal bulb. STRATIGRAPHIC RANGE.- Uppermost Zone E7- E1O? Due to poor sampling of suitable paleoenvironments the stratigraphic range is uncertain. GEOGRAPHIC DISTRIBUTION.- Worldwide at low to mid latitudes. Rare in open-ocean oligotrophic assemblages, occasionally common in paleoupwellingl high productivity environments. STABLE ISOTOPE PALEOBIOLOGY.- Clavigerinella akersi registers very high ò18O and low ò13C compared to other co-existing planktonic species indicating that it lived in cold, 12C-rich water inasses indicative of a deep subtherrnocline habitat or upwelling (Coxall, 2000). |
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| Systematics: | ||||||
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15 Classis Foraminifera Genus Clavigerinella Species Clavigerinella akersi 24 Genus Clavigerinella Species Clavigerinella akersi 35 Ordo Foraminiferida Superfamilia Globigerinaceae Familia Hantkeninidae Genus Clavigerinella |
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| Synonym list: | ||||||
| Toumarkine & Luterbacher (1985): 1957 Clavigerinella akersi Bolli et al.. - Bolli et al. : p.30 pl 3 figs 5a-b (type reference)
1985 Clavigerinella akersi Bolli et al.. - Toumarkine & Luterbacher : p.120 figs 22.10-14
Bolli (1957): 1948 Hastigerinella eocanica Nuttall. - Cushman & Renz : p. 38 pl. 7, fig. 17
1955 Hastigerinella eocanica Nuttall. - Weiss : p. 309 pl. 2, figs. 11, 13
1957 Clavigerinella akersi Bolli et al.. - Bolli : p. 272 pl. 35, figs. 1a-2b
1957 Clavigerinella akersi Bolli et al.. - Bolli et al. : p. 30 pl. 3, figs. 5a-b
Pearson et al. (2006): 1957 Clavigerinella akersi Bolli et al.. - Bolli et al. : p.30 pl. 3; fig. 5a-b [middle Eocene, Navet Fm., Trinidad]
1979 Clavigerinella eocanica akersi Bolli et al.. - Blow : p. 1201, 1202 pl. 157, fig. 10;
pl. 162, fig. 4 [middle Eocene, Zone PIO, Kane 9-C Piston Core,
Endeavour Seamount, equatorial Atlantic Ocean]
2006 Clavigerinella akersi Bolli et al.. - Pearson et al. : p.219 pl. 8.1; fig. 1-9 (Pl. 8.1, Figs. 1-3; new SEMs of the holotype of
Clavigerinella akersi Bolli, Loeblich and Tappan)
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| Was used in synonym list of: | ||||||
| Specimen: | ||||||
| Cushman Collection - Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM P4550 |
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| References: | ||||||
Cushman,J.A. and Renz,H.H. (1948): Weiss,L. (1955): Bolli,H.M.; Loeblich,A.R. and Tappan,H. (1957): Bolli,H.M. (1957): Blow,W.H. (1979): Toumarkine,M. and Luterbacher,H.P. (1985): 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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