Gansserina

Gansserina is a genus of planktonic Foraminifera (Kingdom Protista ), included in the globigerinid family Globotruncanidae, that has a fairly wide distribution in the Upper Cretaceous (Maastrichtian). The type species is Globotruncana tlansseri' Bolli,1951.

The test of Gansserina is coiled in a low to flat trochospiral. The spiral side is flat, with curved, raised and oblique sutures. The umbilical side is convex with radial depressed sutures and a wide umbilicus containing portici (asymmetrical apertural flaps) and tegilla (umbilical coverings). A distinct peripheral keel runs along the edge of the spiral side while the periphery on the umblical side may have an incompletely developed keel formed by pustules. Early chambers are globular, later ones rhomboidal in section. The wall is calcareous, perforate and pustulate, especially on the umbilical side. The primary aperture is interiomarginal, borderd by a wide porticus (flap).

Gansserina gansseri, based on stable isotope study (C₁₃ and O₁₈) of specimens from Lower Maastrichtian marine sediments, is thought to have lived at intermediate depths, within the paleothermocline.

References

• Alfred R. Loeblich Jr and Helen Tappan, 1964. Sarcodina Chiefly "Thecamoebians" and Foraminiferida; Treatise on Invertebrate Paleontology, Part C Protista 2. Geological Society of America and University of Kansas Press.
• Loeblich, A.R and H. Tappan,1988. Forminiferal Genera and their Classification.
• Sigal Abramovich, et al 2003. Characterization of late Campanian and Maastrichtian planktonic foraminiferal depth habitats and vital activities based on stable isotopes. Palaeogeography, Palaeoclimatology, Palaeoecology 202 (2003) 1-29