Guembelinamidwayensis Cushman, 1940:65, pl. 11: fig. 15 [Paleocene, Sumter Co., Alabama],—Cushman and Todd, 1946:58, pl. 10: fig. 15 [Paleocene, Arkansas].—Cushman, 1951:37, pl. 11: figs. 7, 8 [Paleocene, Alabama, Arkansas, and Texas].
Chiloguembelinamidwayensis (Cushman).—Loeblich and Tappan, 1957a: 179, pl. 41: fig. 3 [Danian, Clayton Fm., Alabama], pl. 43: fig. 7a,b [Wills Point Fm., Texas], pl. 45: fig. 9a,b [Porters Creek Clay, Alabama].—D'Hondt, 1991:173, pl. 2: fig. 13 [Zone Pa, DSDP Site 528/31/CC: 14-15 cm; Walvis Ridge, South Atlantic Ocean], fig. 14 [Zone Pa, DSDP Site 577/12/5: 34-36 cm; Shatsky Rise, northwestern Pacific Ocean], [Not Olsson, 1970:601, pl, 91: fig. 8.—MacLeod, 1993:66, pl. 6: figs. 3, 4, 7-10.—Huber and Boersma, 1994:282, pl. 3:fig.3a-d.]
Chiloguembelinamidwayensis midwayensis (Cushman).—Beckmann, 1957:90, text-fig. 14 (24-27), pl. 21; fig. la,b [Globorotaliatrinidadensis through Globorotaliavelascoensis Zones, lower Lizard Springs Fm., Trinidad],
Chiloguembelinamidwayensis strombiformis Beckmann, 1957:90, text-fig. 14 (28-31), pl. 21: fig. 6a-c [Globorotaliapseudomenardii and Globorotaliavelascoensis Zones, lower Lizard Springs Fm., Trinidad], [Olsson et al. 1999]
Taxonomic discussion: Chiloguembelinamidwayensisstrombiformis Beckman, 1957, was erected as a Paleocene subspecies of Chiloguembelinamidwayensis (Cushman, 1940). The chambers of the C. midwayensis strombiformis holotype (Plate 13: Figures 12, 13) expand much more rapidly in depth (thickness) than do those of C. midwayensis sensu stricto; in late-stage chambers of C. midwayensis sensu stricto, chamber breadth consistently exceeds chamber depth. [Olsson et al. 1999]
Distinguishing features: Parent taxon (Chiloguembelina): Test subtriangular in outline, biserial throughout or rarely with multiserial final chambers; aperture a simple arched opening at base of the final chamber, with a narrow rim on one margin and a broad collar or flange directed toward one of the flat sides of the test, lacking an infolded margin or internal plate. Rarely with multiple apertures. This taxon: Test small, compressed, and rapidly tapering. Early chambers subspherical, later chambers are broadercross the coiling axis and overlap the immediately preceding chambers, can extend almost across test. Aperture of each chamber exhibits only one distinct lateral flange
NB These concise distinguishing features statements are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus. They are being edited as the site is developed and comments on them are especially welcome.
sp chamber shape:
umb chbr shape:
periph margin shape:
umbilical or test sutures:
N.B. These characters are used for advanced search. N/A - not applicable
Biogeography and Palaeobiology
Geographic distributionChiloguembelinamidwayensis occurred at low and middle latitudes (Beckmann, 1957; Boersma, 1984b; D'Hondt and Keller, 1991; Liu and Olsson, 1992) (Figure 35). [Olsson et al. 1999] Isotope paleobiologyThe stable isotopic signature of C. midwayensis suggests that this species inhabited a deeperwater or cooler-season habitat than most co-occurring taxa (Boersma and Premoli Silva, 1983; D'Hondt and Zachos, 1993). [Olsson et al. 1999] Phylogenetic relationsChiloguembelinamidwayensis evolved from C. morsei (Kline) (D'Hondt, 1991). [Olsson et al. 1999]
Geological Range: Notes: Zone P a (D'Hondt, 1991) to Zone P5 (Beckman, 1957; Boersma, 1984b). [Olsson et al. 1999] Last occurrence (top): within P5 zone (55.96-57.1Ma, top in Thanetian stage). Data source: Olsson et al. 1999 First occurrence (base): within Pa zone (65.72-66Ma, base in Danian stage). Data source: Olsson et al. 1999
Plot of occurrence data:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes