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Species Pseudohastigerina sharkriverensis Berggren & Olsson 1967 | ||||||
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| Diagnosis / Definition: | ||||||
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Pearson et al. (2006): DESCRIPTION. Type of wall: Smooth, normal perforate. Test morphology: Test planispiral, compressed, tightly coiled, involute, oval to quadrate in outline, slightly lobulate, chambers, inflated, globular; in umbilical view 6 chambers in ultimate whorl with the final 3 composing about two-thirds of the test size, first 4 chambers increasing rapidly in size and the final 2 chambers more gradually in size, ultimate chamber sometimes slightly reduced in size, sutures moderately depressed, straight to slightly curved, umbilicus small, circular in shape; in edge view chambers much inflated, oval to nearly circular in outline, primary aperture an oval low arch, bordered by a narrow lip, bipartite apertures a common feature in adult specimens, test compressed with a rounded periphery; peripheral margin perforate. Size: Maximum diameter of holotype 0.35 mm, thickness 0.20 mm. |
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| Discussion / Comments: | ||||||
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Pearson et al. (2006): DISTINGUISHTNG FEATURES.- Pseudohastigerina sharkriverensis is characterized by its large oval to quadrate test, much inflated globular chambers, the slower chamber growth in the final 3 chambers and the common development of bipartite apertures in the final chamber. In edge view the chambers are much inflated in contrast to the more compressed chambers in P. wilcoxensis. DISCUSSION.- This species has not been widely recorded in the published literature, which may in part be due to its mid-latitude biogeographic restriction. The only discussion of the species was by Blow (1 979) who stated (p. 11 92) "In the writer's view, the production of the sharkriverensis-morphotype is a strict allometric and orthogenetic development of the wilcoxensis-morphotypes to the limits imposed by the geometry of planispirally coiled forms with inflated chambers". He apparently based his opinion on his belief that the development of a bipartite apertural system was due to a tightening of the chamber coil and greater inflation of chambers that first occurred in P wilcoxensis. However, bipartite apertures are also seen in Pseudohastigerina micra (Cole) which has much compressed chambers, so that bipartite apertures appear to be a feature of the Pseudohastigerina group of species. The evolution of P. sharkriverensis from P. wilcoxensis can not be regarded as strictly an allometric development because there is a change in chamber shape. Blow suggested that Biglobigerinella kerisensis Suleymanov (1966) might be a senior synonym of P sharkriverensis. Biglobigerinella kerisensis was described from the upper Eocene of Kizil Kum, central Asia of the former Soviet Union. Scanning electron micrographs of the holotype of this species (Pl. 14.4, Figs. 13-15) show a deformed specimen with an asymmetrical ultimate chamber which extends over and obscures the umbilical area of one side. Although the specimen appears to be planispiral, it is difficult to make a meaningful morphological comparison with P. sharkriverensis without additional specimens. Since P sharkriverensis is not known to range above the middle Eocene and B. kerisensis is poorly known and not well documented, it is advisable to use the former name. Globigerinella pseudovoluta Bandy (1949) was also mentioned by Blow as a possible senior synonym of P sharkriverensis but this species is more properly placed in P. wilcoxensis because the chambers are more compressed in edge view, the aperture is highly arched, and there is a regular increase in chamber size, all typical features of P. wilcoxensis. PHYLOGENETIC RELATIONSHIPS.- Pseudohastigerina sharkriverensis evolved from P. wilcoxensis by an increase in size of the test, a slowly of chamber size increase in the last few chambers of the ultimate whorl, and by a change in chamber shape from compressed to globular inflated chambers. The aperture is reduced to a low arch in the transition. STRATIGRAPHIC RANGE.- Middle Eocene, Zone E7? to Zone E1 3? GEOGRAPHIC DISTRIBUTION.- Apparently restricted distribution in mid latitudes. STABLE ISOTOPE PALEOBIOL0GY.- No data available. |
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| Systematics: | ||||||
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35 Ordo Foraminiferida Superfamilia Globigerinaceae Familia Hedbergellidae Genus Pseudohastigerina Species Pseudohastigerina sharkriverensis |
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| Synonym list: | ||||||
| Pearson et al. (2006): p 1953 Globigerinella voluta White. - Subbotina : p.87 pl. 13; fig. 13a-b [middle Eocene Acarinina zone, Kuban River, Northern Caucasus];
fig. 14a-b [lower-middle Eocene Zone of conical Globorotalia, Khieu River, northern Caucasus] (not fig. 15a-b = Pseudohastigerina wileoxensis); [Not White, 1928]
? 1966 Biglobigerinella kerisensis Suleymanov. - Suleymanov : p.148 pl. 1; fig. 1a, b [upper Eocene of Kizil Kum, central Asia]
1967 Pseudohastigerina sharkriverensis Berggren & Olsson. - Berggren et al. : p.280 pl. 1, fig. 7-8 (holotype); 9- 11 (paratype); text-fig. 7, 1a-9c (paratypes);
text-fig. 8, 10a- 14c (paratypes) [middle Eocene, Shark
River Fm., New Jersey]
1972 Pseudohastigerina sharkriverensis Berggren & Olsson. - McKeel & Lipps : p.83 pl. 1; fig. 7a, b [middle Eocene, Tyee Fm., Coast Range,
Oregon]
1979 Pseudohastigerina sharkriverensis Berggren & Olsson. - Blow : p.1191 pl. 252, fig. 5-7 [lower Eocene Zone P9, Tuilerie de Gan, southwest France];
fig. 8- 10 [lower Eocene Zone P 12- 14, Steenberg, stratotype Ledian, Bambrugge, Belgium]
2006 Pseudohastigerina sharkriverensis Berggren & Olsson. - Pearson et al. : p.429 pl. 14.4; fig. 9-16 (Pl. 14.4, Figs. 9, 10: new SEMs of holotype of
Pseudohastigerina sharkriverensis Berggren and
Olsson)
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| Was used in synonym list of: | ||||||
| Specimen: | ||||||
| Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM 509801 Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM 509802 |
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| References: | ||||||
Subbotina,N.N. (1953): Suleymanov,I.V.. (1966): Berggren,W.A.; Olsson,R.K. and Reyment,R.A. (1967): McKeel,D.R.. and Lipps,J.H. (1972): Blow,W.H. (1979): 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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